{-
(c) The University of Glasgow 2006
(c) The AQUA Project, Glasgow University, 1996-1998

-}

{-# LANGUAGE CPP #-}
{-# LANGUAGE TupleSections, ScopedTypeVariables, MultiWayIf #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE LambdaCase #-}

{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}

-- | Typecheck type and class declarations
module GHC.Tc.TyCl (
        tcTyAndClassDecls,

        -- Functions used by GHC.Tc.TyCl.Instance to check
        -- data/type family instance declarations
        kcConDecls, tcConDecls, DataDeclInfo(..),
        dataDeclChecks, checkValidTyCon,
        tcFamTyPats, tcTyFamInstEqn,
        tcAddTyFamInstCtxt, tcMkDataFamInstCtxt, tcAddDataFamInstCtxt,
        unravelFamInstPats, addConsistencyConstraints,
        checkFamTelescope
    ) where

import GHC.Prelude

import GHC.Driver.Env
import GHC.Driver.DynFlags
import GHC.Driver.Config.HsToCore

import GHC.Hs

import GHC.Tc.Errors.Types
import GHC.Tc.TyCl.Build
import GHC.Tc.Solver( pushLevelAndSolveEqualities, pushLevelAndSolveEqualitiesX
                    , reportUnsolvedEqualities )
import GHC.Tc.Utils.Monad
import GHC.Tc.Utils.Env
import GHC.Tc.Utils.Unify( unifyType, emitResidualTvConstraint )
import GHC.Tc.Types.Constraint( emptyWC )
import GHC.Tc.Validity
import GHC.Tc.Zonk.Type
import GHC.Tc.Zonk.TcType
import GHC.Tc.TyCl.Utils
import GHC.Tc.TyCl.Class
import {-# SOURCE #-} GHC.Tc.TyCl.Instance( tcInstDecls1 )
import {-# SOURCE #-} GHC.Tc.Module( checkBootDeclM )
import GHC.Tc.Deriv (DerivInfo(..))
import GHC.Tc.Gen.HsType
import GHC.Tc.Instance.Class( AssocInstInfo(..) )
import GHC.Tc.Utils.TcMType
import GHC.Tc.Utils.TcType
import GHC.Tc.Instance.Family
import GHC.Tc.Types.Origin
import GHC.Tc.Types.LclEnv

import GHC.Builtin.Types (oneDataConTy,  unitTy, makeRecoveryTyCon )

import GHC.Rename.Env( lookupConstructorFields )

import GHC.Core.Multiplicity
import GHC.Core.FamInstEnv ( mkBranchedCoAxiom, mkCoAxBranch )
import GHC.Core.Coercion
import GHC.Core.Type
import GHC.Core.TyCo.Rep   -- for checkValidRoles
import GHC.Core.TyCo.Ppr( pprTyVars )
import GHC.Core.Class
import GHC.Core.Coercion.Axiom
import GHC.Core.TyCon
import GHC.Core.DataCon
import GHC.Core.Unify

import GHC.Types.Error
import GHC.Types.Id
import GHC.Types.Id.Make
import GHC.Types.Var
import GHC.Types.Var.Env
import GHC.Types.Var.Set
import GHC.Types.Name
import GHC.Types.Name.Set
import GHC.Types.Name.Env
import GHC.Types.SrcLoc
import GHC.Types.SourceFile
import GHC.Types.TypeEnv
import GHC.Types.Unique
import GHC.Types.Basic
import qualified GHC.LanguageExtensions as LangExt

import GHC.Data.FastString
import GHC.Data.Maybe
import GHC.Data.List.SetOps( minusList, equivClasses )

import GHC.Unit
import GHC.Unit.Module.ModDetails

import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Utils.Constants (debugIsOn)
import GHC.Utils.Misc

import Language.Haskell.Syntax.Basic (FieldLabelString(..))

import Control.Monad
import Data.Foldable ( toList, traverse_ )
import Data.Functor.Identity
import Data.List ( partition)
import Data.List.NonEmpty ( NonEmpty(..) )
import qualified Data.List.NonEmpty as NE
import Data.Traversable ( for )
import Data.Tuple( swap )

{-
************************************************************************
*                                                                      *
\subsection{Type checking for type and class declarations}
*                                                                      *
************************************************************************

Note [Grouping of type and class declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tcTyAndClassDecls is called on a list of `TyClGroup`s. Each group is a strongly
connected component of mutually dependent types and classes. We kind check and
type check each group separately to enhance kind polymorphism. Take the
following example:

  type Id a = a
  data X = X (Id Int)

If we were to kind check the two declarations together, we would give Id the
kind * -> *, since we apply it to an Int in the definition of X. But we can do
better than that, since Id really is kind polymorphic, and should get kind
forall (k::*). k -> k. Since it does not depend on anything else, it can be
kind-checked by itself, hence getting the most general kind. We then kind check
X, which works fine because we then know the polymorphic kind of Id, and simply
instantiate k to *.

Note [Check role annotations in a second pass]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Role inference potentially depends on the types of all of the datacons declared
in a mutually recursive group. The validity of a role annotation, in turn,
depends on the result of role inference. Because the types of datacons might
be ill-formed (see #7175 and Note [rejigConRes]) we must check
*all* the tycons in a group for validity before checking *any* of the roles.
Thus, we take two passes over the resulting tycons, first checking for general
validity and then checking for valid role annotations.
-}

tcTyAndClassDecls :: [TyClGroup GhcRn]      -- Mutually-recursive groups in
                                            -- dependency order
                  -> TcM ( TcGblEnv         -- Input env extended by types and
                                            -- classes
                                            -- and their implicit Ids,DataCons
                         , [InstInfo GhcRn] -- Source-code instance decls info
                         , [DerivInfo]      -- Deriving info
                         , ThBindEnv        -- TH binding levels
                         )
-- Fails if there are any errors
tcTyAndClassDecls :: [TyClGroup GhcRn]
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
tcTyAndClassDecls [TyClGroup GhcRn]
tyclds_s
  -- The code recovers internally, but if anything gave rise to
  -- an error we'd better stop now, to avoid a cascade
  -- Type check each group in dependency order folding the global env
  = TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
forall r. TcM r -> TcM r
checkNoErrs (TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
 -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv))
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
forall a b. (a -> b) -> a -> b
$ [InstInfo GhcRn]
-> [DerivInfo]
-> ThBindEnv
-> [TyClGroup GhcRn]
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
fold_env [] [] ThBindEnv
forall a. NameEnv a
emptyNameEnv [TyClGroup GhcRn]
tyclds_s
  where
    fold_env :: [InstInfo GhcRn]
             -> [DerivInfo]
             -> ThBindEnv
             -> [TyClGroup GhcRn]
             -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
    fold_env :: [InstInfo GhcRn]
-> [DerivInfo]
-> ThBindEnv
-> [TyClGroup GhcRn]
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
fold_env [InstInfo GhcRn]
inst_info [DerivInfo]
deriv_info ThBindEnv
th_bndrs []
      = do { gbl_env <- TcRnIf TcGblEnv TcLclEnv TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
           ; return (gbl_env, inst_info, deriv_info, th_bndrs) }
    fold_env [InstInfo GhcRn]
inst_info [DerivInfo]
deriv_info ThBindEnv
th_bndrs (TyClGroup GhcRn
tyclds:[TyClGroup GhcRn]
tyclds_s)
      = do { (tcg_env, inst_info', deriv_info', th_bndrs')
               <- TyClGroup GhcRn
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
tcTyClGroup TyClGroup GhcRn
tyclds
           ; setGblEnv tcg_env $
               -- remaining groups are typechecked in the extended global env.
             fold_env (inst_info' ++ inst_info)
                      (deriv_info' ++ deriv_info)
                      (th_bndrs' `plusNameEnv` th_bndrs)
                      tyclds_s }

tcTyClGroup :: TyClGroup GhcRn
            -> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
-- Typecheck one strongly-connected component of type, class, and instance decls
-- See Note [TyClGroups and dependency analysis] in GHC.Hs.Decls
tcTyClGroup :: TyClGroup GhcRn
-> TcM (TcGblEnv, [InstInfo GhcRn], [DerivInfo], ThBindEnv)
tcTyClGroup (TyClGroup { group_tyclds :: forall pass. TyClGroup pass -> [LTyClDecl pass]
group_tyclds = [LTyClDecl GhcRn]
tyclds
                       , group_roles :: forall pass. TyClGroup pass -> [LRoleAnnotDecl pass]
group_roles  = [LRoleAnnotDecl GhcRn]
roles
                       , group_kisigs :: forall pass. TyClGroup pass -> [LStandaloneKindSig pass]
group_kisigs = [LStandaloneKindSig GhcRn]
kisigs
                       , group_instds :: forall pass. TyClGroup pass -> [LInstDecl pass]
group_instds = [LInstDecl GhcRn]
instds })
  = do { let role_annots :: RoleAnnotEnv
role_annots = [LRoleAnnotDecl GhcRn] -> RoleAnnotEnv
mkRoleAnnotEnv [LRoleAnnotDecl GhcRn]
roles

           -- Step 1: Typecheck the standalone kind signatures and type/class declarations
       ; String -> SDoc -> TcRn ()
traceTc String
"---- tcTyClGroup ---- {" SDoc
forall doc. IsOutput doc => doc
empty
       ; String -> SDoc -> TcRn ()
traceTc String
"Decls for" ([IdGhcP 'Renamed] -> SDoc
forall a. Outputable a => a -> SDoc
ppr ((GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> IdGhcP 'Renamed)
-> [GenLocated SrcSpanAnnA (TyClDecl GhcRn)] -> [IdGhcP 'Renamed]
forall a b. (a -> b) -> [a] -> [b]
map (TyClDecl GhcRn -> IdP GhcRn
TyClDecl GhcRn -> IdGhcP 'Renamed
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (TyClDecl GhcRn -> IdGhcP 'Renamed)
-> (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn)
-> GenLocated SrcSpanAnnA (TyClDecl GhcRn)
-> IdGhcP 'Renamed
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn
forall l e. GenLocated l e -> e
unLoc) [LTyClDecl GhcRn]
[GenLocated SrcSpanAnnA (TyClDecl GhcRn)]
tyclds))
       ; (tyclss_with_validity_infos, data_deriv_info, kindless) <-
           NameEnv TcTyThing
-> TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet)
-> TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet)
forall r. NameEnv TcTyThing -> TcM r -> TcM r
tcExtendKindEnv ([LTyClDecl GhcRn] -> NameEnv TcTyThing
mkPromotionErrorEnv [LTyClDecl GhcRn]
tyclds) (TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet)
 -> TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet))
-> TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet)
-> TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet)
forall a b. (a -> b) -> a -> b
$ -- See Note [Type environment evolution]
           do { kisig_env <- [(Name, Type)] -> NameEnv Type
forall a. [(Name, a)] -> NameEnv a
mkNameEnv ([(Name, Type)] -> NameEnv Type)
-> IOEnv (Env TcGblEnv TcLclEnv) [(Name, Type)]
-> IOEnv (Env TcGblEnv TcLclEnv) (NameEnv Type)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (GenLocated SrcSpanAnnA (StandaloneKindSig GhcRn)
 -> IOEnv (Env TcGblEnv TcLclEnv) (Name, Type))
-> [GenLocated SrcSpanAnnA (StandaloneKindSig GhcRn)]
-> IOEnv (Env TcGblEnv TcLclEnv) [(Name, Type)]
forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
forall (f :: * -> *) a b.
Applicative f =>
(a -> f b) -> [a] -> f [b]
traverse LStandaloneKindSig GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (Name, Type)
GenLocated SrcSpanAnnA (StandaloneKindSig GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Name, Type)
tcStandaloneKindSig [LStandaloneKindSig GhcRn]
[GenLocated SrcSpanAnnA (StandaloneKindSig GhcRn)]
kisigs
              ; tcTyClDecls tyclds kisig_env role_annots }
       ; let tyclss = ((TyCon, [TyFamEqnValidityInfo]) -> TyCon)
-> [(TyCon, [TyFamEqnValidityInfo])] -> [TyCon]
forall a b. (a -> b) -> [a] -> [b]
map (TyCon, [TyFamEqnValidityInfo]) -> TyCon
forall a b. (a, b) -> a
fst [(TyCon, [TyFamEqnValidityInfo])]
tyclss_with_validity_infos
           -- Step 1.5: Make sure we don't have any type synonym cycles

       ; traceTc "Starting synonym cycle check" (ppr tyclss)
       ; home_unit <- hsc_home_unit <$> getTopEnv
       ; checkSynCycles (homeUnitAsUnit home_unit) tyclss tyclds
       ; traceTc "Done synonym cycle check" (ppr tyclss)

           -- Step 2: Perform the validity check on those types/classes
           -- We can do this now because we are done with the recursive knot
           -- Do it before Step 3 (adding implicit things) because the latter
           -- expects well-formed TyCons
       ; traceTc "Starting validity check" (ppr tyclss)
       ; tyclss <- tcExtendTyConEnv tyclss $
           -- NB: put the TyCons in the environment for validity checking,
           -- as we might look them up in checkTyConConsistentWithBoot.
           -- See Note [TyCon boot consistency checking].
          fmap concat . for tyclss_with_validity_infos $ \ (TyCon
tycls, [TyFamEqnValidityInfo]
ax_validity_infos) ->
          do { SDoc -> Name -> TcRn () -> TcRn ()
forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"type family") (TyCon -> Name
tyConName TyCon
tycls) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
               TyCon -> TcRn () -> TcRn ()
forall a. TyCon -> TcM a -> TcM a
tcAddClosedTypeFamilyDeclCtxt TyCon
tycls (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                 (TyFamEqnValidityInfo -> TcRn ())
-> [TyFamEqnValidityInfo] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (TyCon -> TyFamEqnValidityInfo -> TcRn ()
checkTyFamEqnValidityInfo TyCon
tycls) [TyFamEqnValidityInfo]
ax_validity_infos
             ; TyCon -> TcM [TyCon]
checkValidTyCl TyCon
tycls }

       ; traceTc "Done validity check" (ppr tyclss)
       ; mapM_ (recoverM (return ()) . checkValidRoleAnnots role_annots) tyclss
           -- See Note [Check role annotations in a second pass]

       ; traceTc "---- end tcTyClGroup ---- }" empty

           -- Step 3: Add the implicit things;
           -- we want them in the environment because
           -- they may be mentioned in interface files
       ; (gbl_env, th_bndrs) <- addTyConsToGblEnv tyclss

           -- Step 4: check instance declarations
       ; (gbl_env', inst_info, datafam_deriv_info, th_bndrs') <-
         setGblEnv gbl_env $
         tcInstDecls1 instds

       ; let deriv_info = [DerivInfo]
datafam_deriv_info [DerivInfo] -> [DerivInfo] -> [DerivInfo]
forall a. [a] -> [a] -> [a]
++ [DerivInfo]
data_deriv_info
       ; let gbl_env'' = TcGblEnv
gbl_env'
                { tcg_ksigs = tcg_ksigs gbl_env' `unionNameSet` kindless }
       ; return (gbl_env'', inst_info, deriv_info,
                 th_bndrs' `plusNameEnv` th_bndrs) }

-- Gives the kind for every TyCon that has a standalone kind signature
type KindSigEnv = NameEnv Kind

tcTyClDecls
  :: [LTyClDecl GhcRn]
  -> KindSigEnv
  -> RoleAnnotEnv
  -> TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet)
tcTyClDecls :: [LTyClDecl GhcRn]
-> NameEnv Type
-> RoleAnnotEnv
-> TcM ([(TyCon, [TyFamEqnValidityInfo])], [DerivInfo], NameSet)
tcTyClDecls [LTyClDecl GhcRn]
tyclds NameEnv Type
kisig_env RoleAnnotEnv
role_annots
  = do {    -- Step 1: kind-check this group and returns the final
            -- (possibly-polymorphic) kind of each TyCon and Class
            -- See Note [Kind checking for type and class decls]
         (tc_tycons, kindless) <- TcM ([TyCon], NameSet) -> TcM ([TyCon], NameSet)
forall r. TcM r -> TcM r
checkNoErrs (TcM ([TyCon], NameSet) -> TcM ([TyCon], NameSet))
-> TcM ([TyCon], NameSet) -> TcM ([TyCon], NameSet)
forall a b. (a -> b) -> a -> b
$
                                  NameEnv Type -> [LTyClDecl GhcRn] -> TcM ([TyCon], NameSet)
kcTyClGroup NameEnv Type
kisig_env [LTyClDecl GhcRn]
tyclds
            -- checkNoErrs: If the TyCons are ill-kinded, stop now.  Else we
            -- can get follow-on errors. Example: #23252, where the TyCon
            -- had an ill-scoped kind forall (d::k) k (a::k). blah
            -- and that ill-scoped kind made role inference fall over.

       ; traceTc "tcTyAndCl generalized kinds" (vcat (map ppr_tc_tycon tc_tycons))

            -- Step 2: type-check all groups together, returning
            -- the final TyCons and Classes
            --
            -- NB: We have to be careful here to NOT eagerly unfold
            -- type synonyms, as we have not tested for type synonym
            -- loops yet and could fall into a black hole.
       ; fixM $ \ ~([(TyCon, [TyFamEqnValidityInfo])]
rec_tyclss_with_validity_infos, [DerivInfo]
_, NameSet
_) -> do
           { tcg_env <- TcRnIf TcGblEnv TcLclEnv TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
                 -- Forced so we don't retain a reference to the TcGblEnv
           ; let !src  = TcGblEnv -> HscSource
tcg_src TcGblEnv
tcg_env
                 rec_tyclss = ((TyCon, [TyFamEqnValidityInfo]) -> TyCon)
-> [(TyCon, [TyFamEqnValidityInfo])] -> [TyCon]
forall a b. (a -> b) -> [a] -> [b]
map (TyCon, [TyFamEqnValidityInfo]) -> TyCon
forall a b. (a, b) -> a
fst [(TyCon, [TyFamEqnValidityInfo])]
rec_tyclss_with_validity_infos
                 roles = HscSource -> RoleAnnotEnv -> [TyCon] -> Name -> [Role]
inferRoles HscSource
src RoleAnnotEnv
role_annots [TyCon]
rec_tyclss

                 -- Populate environment with knot-tied ATyCon for TyCons
                 -- NB: if the decls mention any ill-staged data cons
                 -- (see Note [Recursion and promoting data constructors])
                 -- we will have failed already in kcTyClGroup, so no worries here
           ; (tycons, data_deriv_infos) <-
             tcExtendRecEnv (zipRecTyClss tc_tycons rec_tyclss) $

                 -- Also extend the local type envt with bindings giving
                 -- a TcTyCon for each knot-tied TyCon or Class
                 -- See Note [Type checking recursive type and class declarations]
                 -- and Note [Type environment evolution]
             tcExtendKindEnvWithTyCons tc_tycons $

                 -- Kind and type check declarations for this group
               mapAndUnzipM (tcTyClDecl roles) tyclds
           ; return (tycons, concat data_deriv_infos, kindless)
           } }
  where
    ppr_tc_tycon :: TyCon -> SDoc
ppr_tc_tycon TyCon
tc = SDoc -> SDoc
forall doc. IsLine doc => doc -> doc
parens ([SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep [ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Name
tyConName TyCon
tc) SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> SDoc
forall doc. IsLine doc => doc
comma
                                  , [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [TyConBinder]
tyConBinders TyCon
tc) SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> SDoc
forall doc. IsLine doc => doc
comma
                                  , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Type
tyConResKind TyCon
tc)
                                  , Bool -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Bool
isTcTyCon TyCon
tc) ])

zipRecTyClss :: [TcTyCon]
             -> [TyCon]           -- Knot-tied
             -> [(Name,TyThing)]
-- Build a name-TyThing mapping for the TyCons bound by decls
-- being careful not to look at the knot-tied [TyThing]
-- The TyThings in the result list must have a visible ATyCon,
-- because typechecking types (in, say, tcTyClDecl) looks at
-- this outer constructor
zipRecTyClss :: [TyCon] -> [TyCon] -> [(Name, TyThing)]
zipRecTyClss [TyCon]
tc_tycons [TyCon]
rec_tycons
  = [ (Name
name, TyCon -> TyThing
ATyCon (Name -> TyCon
get Name
name)) | TyCon
tc_tycon <- [TyCon]
tc_tycons, let name :: Name
name = TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
tc_tycon ]
  where
    rec_tc_env :: NameEnv TyCon
    rec_tc_env :: NameEnv TyCon
rec_tc_env = (TyCon -> NameEnv TyCon -> NameEnv TyCon)
-> NameEnv TyCon -> [TyCon] -> NameEnv TyCon
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyCon -> NameEnv TyCon -> NameEnv TyCon
add_tc NameEnv TyCon
forall a. NameEnv a
emptyNameEnv [TyCon]
rec_tycons

    add_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
    add_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
add_tc TyCon
tc NameEnv TyCon
env = (TyCon -> NameEnv TyCon -> NameEnv TyCon)
-> NameEnv TyCon -> [TyCon] -> NameEnv TyCon
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyCon -> NameEnv TyCon -> NameEnv TyCon
add_one_tc NameEnv TyCon
env (TyCon
tc TyCon -> [TyCon] -> [TyCon]
forall a. a -> [a] -> [a]
: TyCon -> [TyCon]
tyConATs TyCon
tc)

    add_one_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
    add_one_tc :: TyCon -> NameEnv TyCon -> NameEnv TyCon
add_one_tc TyCon
tc NameEnv TyCon
env = NameEnv TyCon -> Name -> TyCon -> NameEnv TyCon
forall a. NameEnv a -> Name -> a -> NameEnv a
extendNameEnv NameEnv TyCon
env (TyCon -> Name
tyConName TyCon
tc) TyCon
tc

    get :: Name -> TyCon
get Name
name = case NameEnv TyCon -> Name -> Maybe TyCon
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv TyCon
rec_tc_env Name
name of
                 Just TyCon
tc -> TyCon
tc
                 Maybe TyCon
other   -> String -> SDoc -> TyCon
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"zipRecTyClss" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Maybe TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr Maybe TyCon
other)

{-
************************************************************************
*                                                                      *
                Kind checking
*                                                                      *
************************************************************************

Note [Kind checking for type and class decls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kind checking is done thus:

   1. Make up a kind variable for each parameter of the declarations,
      and extend the kind environment (which is in the TcLclEnv)

   2. Kind check the declarations

We need to kind check all types in the mutually recursive group
before we know the kind of the type variables.  For example:

  class C a where
     op :: D b => a -> b -> b

  class D c where
     bop :: (Monad c) => ...

Here, the kind of the locally-polymorphic type variable "b"
depends on *all the uses of class D*.  For example, the use of
Monad c in bop's type signature means that D must have kind Type->Type.

Note: we don't treat type synonyms specially (we used to, in the past);
in particular, even if we have a type synonym cycle, we still kind check
it normally, and test for cycles later (checkSynCycles).  The reason
we can get away with this is because we have more systematic TYPE r
inference, which means that we can do unification between kinds that
aren't lifted (this historically was not true.)

The downside of not directly reading off the kinds of the RHS of
type synonyms in topological order is that we don't transparently
support making synonyms of types with higher-rank kinds.  But
you can always specify a CUSK directly to make this work out.
See tc269 for an example.

Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A TcTyCon is one of the variants of TyCon.  First, here are its invariants:

* TcTyCon: a TyCon built with the TcTyCon constructor
  A TcTyCon contains TcTyVars in its binders and kind

* TcTyConBinder: a TyConBinder with a TcTyVar inside (not a TyVar)

* MonoTcTyCon: a form of TcTyCon
  - Flag tcTyConIsPoly = False

  - tyConBinders are TcTyConBinders: they contain TcTyVars, which are
    unification variables (TyVarTv), and whose kinds may contain
    unification variables.

  - tyConKind: the Monomorphic Recursion Principle:
       a MonoTcTyCon has a /monomorphic kind/.
    See Note [No polymorphic recursion in type decls].
    But the tyConKind may contain free unification variables.

  - tyConScopedTyVars is important; maps a Name to a TyVarTv unification variable
    The order matters: Specified then Required variables.
    E.g. in
        data T a (b :: k) = ...
    the order will be [k, a, b].

    We do not allow @k-binders in inference mode, so we do not need to worry about
       data T a @k (b :: k) = ...
    where we would have to put `k` (Specified) after `a` (Required)

    NB: There are no Inferred binders in tyConScopedTyVars; 'a' may
    also be poly-kinded, but that kind variable will be added by
    generaliseTcTyCon, in the passage to a PolyTcTyCon.

  - tyConBinders are irrelevant; we just use tcTyConScopedTyVars
    Well not /quite/ irrelevant:
      * its length gives the number of explicit binders, and so allows us to
        distinguish between the implicit and explicit elements of
        tyConScopedTyVars.
      * at construction time (mkTcTyCon) for a MonoTcTyCon (the call to mkTcTyCon
        in GHC.Tc.Gen.HsType.kcInferDeclHeader) the tyConBinders are used to
        construct the tyConKind; all must have AnonTCB visiblity so we we get
        a monokind.

* PolyTcTyCon: a form of TcTyCon
  - Flag tcTyConIsPoly = True; this is used only to short-cut zonking

  - tyConBinders are still TcTyConBinders, but they are /skolem/ TcTyVars,
    with fixed kinds, and accurate skolem info: no unification variables here

    tyConBinders includes the Inferred binders if any

    tyConBinders uses the Names from the original, renamed program.

  - tcTyConScopedTyVars is irrelevant: just use (binderVars tyConBinders)
    All the types have been swizzled back to use the original Names
    See Note [tyConBinders and lexical scoping] in GHC.Core.TyCon

The main purpose of these TcTyCons is during kind-checking of
type/class declarations (in GHC.Tc.TyCl).  During kind checking we
come upon knowledge of the eventual tycon in bits and pieces, and we
use a TcTyCon to record what we know before we are ready to build the
final TyCon.  Here is the plan:

* Step 1 (inferInitialKinds, called from kcTyClGroup
          inference only, skipped for checking):
  Make a MonoTcTyCon whose binders are TcTyVars,
  that may contain free unification variables.
  See Note [No polymorphic recursion in type decls]

* Step 2 (kcTyClDecl, called from kcTyClGroup)
  Kind-check the declarations of the group; this step just does
  unifications that affect the unification variables created in
  Step 1

* Step 3 (generaliseTcTyCon, called from kcTyClGroup)
  Generalise that MonoTcTyCon to make a PolyTcTyCon
  Its binders are skolem TcTyVars, with accurate SkolemInfo

* Step 4 (tcTyClDecl, called from tcTyClDecls)
  Typecheck the type and class decls to produce a final TyCon
  Its binders are final TyVars, not TcTyVars

Note that a MonoTcTyCon can contain unification variables, but a
PolyTcTyCon does not: only skolem TcTyVars.  See the invariants above.

More details about /kind inference/:

S1) In kcTyClGroup, we use inferInitialKinds to look over the
    declaration of any TyCon that lacks a kind signature or
    CUSK, to determine its "shape"; for example, the number of
    parameters, and any kind signatures.

    We record that shape record that shape in a MonoTcTyCon; it is
    "mono" because it has not been been generalised, and its binders
    and result kind may have free unification variables.

S2) Still in kcTyClGroup, we use kcLTyClDecl to kind-check the
    body (class methods, data constructors, etc.) of each of
    these MonoTcTyCons, which has the effect of filling in the
    metavariables in the tycon's initial kind.

S3) Still in kcTyClGroup, we use generaliseTyClDecl to generalize
    each MonoTcTyCon to get a PolyTcTyCon, with skolem TcTyVars in it,
    and a final, fixed kind.

S4) Finally, back in tcTyClDecls, we extend the environment with
    the PolyTcTyCons, and typecheck each declaration (regardless
    of kind signatures etc) to get final TyCon.

More details about /kind checking/

S5) In kcTyClGroup, we use checkInitialKinds to get the
    utterly-final Kind of all TyCons in the group that
      (a) have a standalone kind signature or
      (b) have a CUSK.
    This produces a PolyTcTyCon, that is, a TcTyCon in which the binders
    and result kind are full of TyVars (not TcTyVars).  No unification
    variables here; everything is in its final form.

Wrinkles:

(W1) When recovering from a type error in a type declaration,
     we want to put the erroneous TyCon in the environment in a
     way that won't lead to more errors.  We use a PolyTcTyCon for this;
     see makeRecoveryTyCon.

(W2) tyConScopedTyVars.  A challenging piece in all of this is that we
     end up taking three separate passes over every declaration:
       - one in inferInitialKind (this pass look only at the head, not the body)
       - one in kcTyClDecls (to kind-check the body)
       - a final one in tcTyClDecls (to desugar)

     In the latter two passes, we need to connect the user-written type
     variables in an LHsQTyVars with the variables in the tycon's
     inferred kind. Because the tycon might not have a CUSK, this
     matching up is, in general, quite hard to do.  (Look through the
     git history between Dec 2015 and Apr 2016 for
     GHC.Tc.Gen.HsType.splitTelescopeTvs!)

     Instead of trying, we just store the list of type variables to
     bring into scope, in the tyConScopedTyVars field of a MonoTcTyCon.
     These tyvars are brought into scope by the calls to
        tcExtendNameTyVarEnv (tcTyConScopedTyVars tycon)
     in kcTyClDecl.

     In a TcTyCon, why is tyConScopedTyVars :: [(Name,TcTyVar)] rather
     than just [TcTyVar]?  Consider these mutually-recursive decls
        data T (a :: k1) b = MkT (S a b)
        data S (c :: k2) d = MkS (T c d)
     We start with k1 bound to kappa1, and k2 to kappa2; so initially
     in the (Name,TcTyVar) pairs the Name is that of the TcTyVar. But
     then kappa1 and kappa2 get unified; so after the zonking in
     'generalise' in 'kcTyClGroup' the Name and TcTyVar may differ.

See also Note [Type checking recursive type and class declarations].

Note [No polymorphic recursion in type decls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In GHC.Tc.HsType.kcInferDeclHeader we use mkAnonTyConBinders to make
the TyConBinders for the MonoTcTyCon.  Here is why.

Should this kind-check (cf #16344)?
  data T ka (a::ka) b  = MkT (T Type           Int   Bool)
                             (T (Type -> Type) Maybe Bool)

Notice that T is used at two different kinds in its RHS.  No!
This should not kind-check.  Polymorphic recursion is known to
be a tough nut.

Many moons ago, we laboriously (with help from the renamer) tried to give T
the polymorphic kind
   T :: forall ka -> ka -> kappa -> Type
where kappa is a unification variable, even in the inferInitialKinds phase
(which is what kcInferDeclHeader is all about).  But that is dangerously
fragile (see #16344), because `kappa` might get unified with `ka`, and
depending on just /when/ that unification happens, the instantiation of T's
kind would vary between different call sites of T.

We encountered similar trickiness with invisible binders in type
declarations: see Note [No inference for invisible binders in type decls]

Solution: the Monomorphic Recursion Principle:

    A MonoTcTyCon has a monomoprhic kind (no foralls!)

See the invariants on MonoTcTyCon in Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon].

So kcInferDeclHeader gives T a straightforward monomorphic kind, with no
quantification whatsoever. That's why we always use mkAnonTyConBinder for
all arguments when figuring out tc_binders.

But notice that (#16344 comment:3)

* Consider this declaration:
    data T2 ka (a::ka) = MkT2 (T2 Type a)

  Starting with inferInitialKinds
  (Step 1 of Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon]):
    MonoTcTyCon binders:
      ka[tyv] :: (kappa1[tau] :: Type)
       a[tyv] :: (ka[tyv]     :: Type)
    MonoTcTyCon kind:
      T2 :: kappa1[tau] -> ka[tyv] -> Type

  Given this kind for T2, in Step 2 we kind-check (T2 Type a)
  from where we see
    T2's first arg:  (kappa1 ~ Type)
    T2's second arg: (ka ~ ka)
  These constraints are soluble by (kappa1 := Type)
  so generaliseTcTyCon (Step 3) gives
    T2 :: forall (k::Type) -> k -> *

  But now the /typechecking/ (Step 4, aka desugaring, tcTyClDecl)
  phase fails, because the call (T2 Type a) in the RHS is ill-kinded.

  We'd really prefer all errors to show up in the kind checking phase.

* This algorithm still accepts (in all phases)
     data T3 ka (a::ka) = forall b. MkT3 (T3 Type b)
  although T3 is really polymorphic-recursive too.
  Perhaps we should somehow reject that.

Note [No inference for invisible binders in type decls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose we have (#22560):
   data T @k (a::k) = MkT (...(T ty)...)
What monokind can we give to T after step 1 of the kind inference
algorithm described in Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon]?
Remember: Step 1 generates a MonoTcTyCon.

It can't be
  T :: kappa1 -> kappa2 -> Type
because the invocation `(T ty)` doesn't have a visible argument for `kappa`.
Nor can it be
  T :: forall k. kappa2 -> Type
because that breaks the Monomorphic Recursion Principle: MonoTcTyCons have
monomorphic kinds; see Note [No polymorphic recursion in type decls]. It could be
  T :: kappa1 ->. kappa2 -> type
where `->.` is a new kind of arrow in kinds, which (like a type-class argument
in terms) is invisibly instantiated.  Or we could fake it with
  T :: forall _. kappa2 -> Type
where `_` is a completely fresh variable, but that seems very smelly and makes it
harder to talk about the Monomorphic Recursion Principle.  Moreover we'd need
some extra fancy types in TyConBinders to record this extra information.

Note that in *terms* we do not allow
  f @a (x::a) = rhs
unless `f` has a type signature.  So we do the same for types:

  We allow `@` binders in data type declarations ONLY if the
  type constructor has a standalone kind signature (or a CUSK).

That means that GHC.Tc.Gen.HsType.kcInferDeclHeader, which is used when we
don't have a kind signature or CUSK, and builds a MonoTcTyCon, we can simply
reject invisible binders outright (GHC.Tc.Gen.HsType.rejectInvisibleBinders);
and continue to use mkAnonTyConBinders as described in
Note [No polymorphic recursion in type decls].

If we get cries of pain we can revist this decision.

Note [CUSKs and PolyKinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider

    data T (a :: *) = MkT (S a)   -- Has CUSK
    data S a = MkS (T Int) (S a)  -- No CUSK

Via inferInitialKinds we get
  T :: * -> *
  S :: kappa -> *

Then we call kcTyClDecl on each decl in the group, to constrain the
kind unification variables.  BUT we /skip/ the RHS of any decl with
a CUSK.  Here we skip the RHS of T, so we eventually get
  S :: forall k. k -> *

This gets us more polymorphism than we would otherwise get, similar
(but implemented strangely differently from) the treatment of type
signatures in value declarations.

However, we only want to do so when we have PolyKinds.
When we have NoPolyKinds, we don't skip those decls, because we have defaulting
(#16609). Skipping won't bring us more polymorphism when we have defaulting.
Consider

  data T1 a = MkT1 T2        -- No CUSK
  data T2 = MkT2 (T1 Maybe)  -- Has CUSK

If we skip the rhs of T2 during kind-checking, the kind of a remains unsolved.
With PolyKinds, we do generalization to get T1 :: forall a. a -> *. And the
program type-checks.
But with NoPolyKinds, we do defaulting to get T1 :: * -> *. Defaulting happens
in quantifyTyVars, which is called from generaliseTcTyCon. Then type-checking
(T1 Maybe) will throw a type error.

Summary: with PolyKinds, we must skip; with NoPolyKinds, we must /not/ skip.

Open type families
~~~~~~~~~~~~~~~~~~
This treatment of type synonyms only applies to Haskell 98-style synonyms.
General type functions can be recursive, and hence, appear in `alg_decls'.

The kind of an open type family is solely determined by its kind signature;
hence, only kind signatures participate in the construction of the initial
kind environment (as constructed by `inferInitialKind'). In fact, we ignore
instances of families altogether in the following. However, we need to include
the kinds of *associated* families into the construction of the initial kind
environment. (This is handled by `allDecls').

See also Note [Kind checking recursive type and class declarations]

Note [Swizzling the tyvars before generaliseTcTyCon]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This Note only applies when /inferring/ the kind of a TyCon.
If there is a separate kind signature, or a CUSK, we take an entirely
different code path.

For inference, consider
   class C (f :: k) x where
      type T f
      op :: D f => blah
   class D (g :: j) y where
      op :: C g => y -> blah

Here C and D are considered mutually recursive.  Neither has a CUSK.
Just before generalisation we have the (un-quantified) kinds
   C :: k1 -> k2 -> Constraint
   T :: k1 -> Type
   D :: k1 -> Type -> Constraint
Notice that f's kind and g's kind have been unified to 'k1'. We say
that k1 is the "representative" of k in C's decl, and of j in D's decl.

Now when quantifying, we'd like to end up with
   C :: forall {k2}. forall k. k -> k2 -> Constraint
   T :: forall k. k -> Type
   D :: forall j. j -> Type -> Constraint

That is, we want to swizzle the representative to have the Name given
by the user. Partly this is to improve error messages and the output of
:info in GHCi.  But it is /also/ important because the code for a
default method may mention the class variable(s), but at that point
(tcClassDecl2), we only have the final class tyvars available.
(Alternatively, we could record the scoped type variables in the
TyCon, but it's a nuisance to do so.)

Notes:

* On the input to generaliseTyClDecl, the mapping between the
  user-specified Name and the representative TyVar is recorded in the
  tyConScopedTyVars of the TcTyCon.  NB: you first need to zonk to see
  this representative TyVar.

* The swizzling is actually performed by swizzleTcTyConBndrs

* We must do the swizzling across the whole class decl. Consider
     class C f where
       type S (f :: k)
       type T f
  Here f's kind k is a parameter of C, and its identity is shared
  with S and T.  So if we swizzle the representative k at all, we
  must do so consistently for the entire declaration.

  Hence the call to check_duplicate_tc_binders is in generaliseTyClDecl,
  rather than in generaliseTcTyCon.

There are errors to catch here.  Suppose we had
   class E (f :: j) (g :: k) where
     op :: SameKind f g -> blah

Then, just before generalisation we will have the (unquantified)
   E :: k1 -> k1 -> Constraint

That's bad!  Two distinctly-named tyvars (j and k) have ended up with
the same representative k1.  So when swizzling, we check (in
check_duplicate_tc_binders) that two distinct source names map
to the same representative.

Here's an interesting case:
    class C1 f where
      type S (f :: k1)
      type T (f :: k2)
Here k1 and k2 are different Names, but they end up mapped to the
same representative TyVar.  To make the swizzling consistent (remember
we must have a single k across C1, S and T) we reject the program.

Another interesting case
    class C2 f where
      type S (f :: k) (p::Type)
      type T (f :: k) (p::Type->Type)

Here the two k's (and the two p's) get distinct Uniques, because they
are seen by the renamer as locally bound in S and T resp.  But again
the two (distinct) k's end up bound to the same representative TyVar.
You might argue that this should be accepted, but it's definitely
rejected (via an entirely different code path) if you add a kind sig:
    type C2' :: j -> Constraint
    class C2' f where
      type S (f :: k) (p::Type)
We get
    • Expected kind ‘j’, but ‘f’ has kind ‘k’
    • In the associated type family declaration for ‘S’

So we reject C2 too, even without the kind signature.  We have
to do a bit of work to get a good error message, since both k's
look the same to the user.

Another case
    class C3 (f :: k1) where
      type S (f :: k2)

This will be rejected too.


Note [Type environment evolution]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As we typecheck a group of declarations the type environment evolves.
Consider for example:
  data B (a :: Type) = MkB (Proxy 'MkB)

We do the following steps:

  1. Start of tcTyClDecls: use mkPromotionErrorEnv to initialise the
     type env with promotion errors
            B   :-> TyConPE
            MkB :-> DataConPE

  2. kcTyCLGroup
      - Do inferInitialKinds, which will signal a promotion
        error if B is used in any of the kinds needed to initialise
        B's kind (e.g. (a :: Type)) here

      - Extend the type env with these initial kinds (monomorphic for
        decls that lack a CUSK)
            B :-> TcTyCon <initial kind>
        (thereby overriding the B :-> TyConPE binding)
        and do kcLTyClDecl on each decl to get equality constraints on
        all those initial kinds

      - Generalise the initial kind, making a poly-kinded TcTyCon

  3. Back in tcTyDecls, extend the envt with bindings of the poly-kinded
     TcTyCons, again overriding the promotion-error bindings.

     But note that the data constructor promotion errors are still in place
     so that (in our example) a use of MkB will still be signalled as
     an error.

  4. Typecheck the decls.

  5. In tcTyClGroup, extend the envt with bindings for TyCon and DataCons


Note [Missed opportunity to retain higher-rank kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In 'kcTyClGroup', there is a missed opportunity to make kind
inference work in a few more cases.  The idea is analogous
to Note [Special case for non-recursive function bindings]:

     * If we have an SCC with a single decl, which is non-recursive,
       instead of creating a unification variable representing the
       kind of the decl and unifying it with the rhs, we can just
       read the type directly of the rhs.

     * Furthermore, we can update our SCC analysis to ignore
       dependencies on declarations which have CUSKs: we don't
       have to kind-check these all at once, since we can use
       the CUSK to initialize the kind environment.

Unfortunately this requires reworking a bit of the code in
'kcLTyClDecl' so I've decided to punt unless someone shouts about it.

Note [Don't process associated types in getInitialKind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Previously, we processed associated types in the thing_inside in getInitialKind,
but this was wrong -- we want to do ATs separately.
The consequence for not doing it this way is #15142:

  class ListTuple (tuple :: Type) (as :: [(k, Type)]) where
    type ListToTuple as :: Type

We assign k a kind kappa[1]. When checking the tuple (k, Type), we try to unify
kappa ~ Type, but this gets deferred because we bumped the TcLevel as we bring
`tuple` into scope. Thus, when we check ListToTuple, kappa[1] still hasn't
unified with Type. And then, when we generalize the kind of ListToTuple (which
indeed has a CUSK, according to the rules), we skolemize the free metavariable
kappa. Note that we wouldn't skolemize kappa when generalizing the kind of ListTuple,
because the solveEqualities in kcInferDeclHeader is at TcLevel 1 and so kappa[1]
will unify with Type.

Bottom line: as associated types should have no effect on a CUSK enclosing class,
we move processing them to a separate action, run after the outer kind has
been generalized.

-}

kcTyClGroup :: KindSigEnv -> [LTyClDecl GhcRn] -> TcM ([PolyTcTyCon], NameSet)

-- Kind check this group, kind generalize, and return the resulting local env
-- This binds the TyCons and Classes of the group, but not the DataCons
-- See Note [Kind checking for type and class decls]
-- and Note [Inferring kinds for type declarations]
--
-- The NameSet returned contains kindless tycon names, without CUSK or SAKS.
kcTyClGroup :: NameEnv Type -> [LTyClDecl GhcRn] -> TcM ([TyCon], NameSet)
kcTyClGroup NameEnv Type
kisig_env [LTyClDecl GhcRn]
decls
  = do  { mod <- IOEnv (Env TcGblEnv TcLclEnv) Module
forall (m :: * -> *). HasModule m => m Module
getModule
        ; traceTc "---- kcTyClGroup ---- {"
                  (text "module" <+> ppr mod $$ vcat (map ppr decls))

          -- Kind checking;
          --    1. Bind kind variables for decls
          --    2. Kind-check decls
          --    3. Generalise the inferred kinds
          -- See Note [Kind checking for type and class decls]

        ; cusks_enabled <- xoptM LangExt.CUSKs <&&> xoptM LangExt.PolyKinds
                    -- See Note [CUSKs and PolyKinds]
        ; let (kindless_decls, kinded_decls) = partitionWith get_kind decls
              kindless_names = [Name] -> NameSet
mkNameSet ([Name] -> NameSet) -> [Name] -> NameSet
forall a b. (a -> b) -> a -> b
$ (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> Name)
-> [GenLocated SrcSpanAnnA (TyClDecl GhcRn)] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> Name
GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> IdGhcP 'Renamed
forall {p :: Pass} {l}.
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
GenLocated l (TyClDecl (GhcPass p)) -> IdGhcP p
get_name [GenLocated SrcSpanAnnA (TyClDecl GhcRn)]
kindless_decls

              get_name GenLocated l (TyClDecl (GhcPass p))
d = TyClDecl (GhcPass p) -> IdP (GhcPass p)
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (GenLocated l (TyClDecl (GhcPass p)) -> TyClDecl (GhcPass p)
forall l e. GenLocated l e -> e
unLoc GenLocated l (TyClDecl (GhcPass p))
d)

              get_kind GenLocated SrcSpanAnnA (TyClDecl GhcRn)
d
                | Just Type
ki <- NameEnv Type -> Name -> Maybe Type
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv Type
kisig_env (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> IdGhcP 'Renamed
forall {p :: Pass} {l}.
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
GenLocated l (TyClDecl (GhcPass p)) -> IdGhcP p
get_name GenLocated SrcSpanAnnA (TyClDecl GhcRn)
d)
                = (GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)
-> Either
     (GenLocated SrcSpanAnnA (TyClDecl GhcRn))
     (GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)
forall a b. b -> Either a b
Right (GenLocated SrcSpanAnnA (TyClDecl GhcRn)
d, Type -> SAKS_or_CUSK
SAKS Type
ki)

                | Bool
cusks_enabled Bool -> Bool -> Bool
&& TyClDecl GhcRn -> Bool
hsDeclHasCusk (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn
forall l e. GenLocated l e -> e
unLoc GenLocated SrcSpanAnnA (TyClDecl GhcRn)
d)
                = (GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)
-> Either
     (GenLocated SrcSpanAnnA (TyClDecl GhcRn))
     (GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)
forall a b. b -> Either a b
Right (GenLocated SrcSpanAnnA (TyClDecl GhcRn)
d, SAKS_or_CUSK
CUSK)

                | Bool
otherwise = GenLocated SrcSpanAnnA (TyClDecl GhcRn)
-> Either
     (GenLocated SrcSpanAnnA (TyClDecl GhcRn))
     (GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)
forall a b. a -> Either a b
Left GenLocated SrcSpanAnnA (TyClDecl GhcRn)
d

        ; checked_tcs <- checkNoErrs $
                         checkInitialKinds kinded_decls
                         -- checkNoErrs because we are about to extend
                         -- the envt with these tycons, and we get
                         -- knock-on errors if we have tycons with
                         -- malformed kinds

        ; inferred_tcs
            <- tcExtendKindEnvWithTyCons checked_tcs  $
               pushLevelAndSolveEqualities unkSkolAnon [] $
                     -- We are going to kind-generalise, so unification
                     -- variables in here must be one level in
               do {  -- Step 1: Bind kind variables for all decls
                    mono_tcs <- inferInitialKinds kindless_decls

                  ; traceTc "kcTyClGroup: initial kinds" $
                    ppr_tc_kinds mono_tcs

                    -- Step 2: Set extended envt, kind-check the decls
                    -- NB: the environment extension overrides the tycon
                    --     promotion-errors bindings
                    --     See Note [Type environment evolution]
                  ; checkNoErrs $
                    tcExtendKindEnvWithTyCons mono_tcs $
                    mapM_ kcLTyClDecl kindless_decls

                  ; return mono_tcs }

        -- Step 3: generalisation
        -- Finally, go through each tycon and give it its final kind,
        -- with all the required, specified, and inferred variables
        -- in order.
        ; let inferred_tc_env = [(Name, TyCon)] -> NameEnv TyCon
forall a. [(Name, a)] -> NameEnv a
mkNameEnv ([(Name, TyCon)] -> NameEnv TyCon)
-> [(Name, TyCon)] -> NameEnv TyCon
forall a b. (a -> b) -> a -> b
$
                                (TyCon -> (Name, TyCon)) -> [TyCon] -> [(Name, TyCon)]
forall a b. (a -> b) -> [a] -> [b]
map (\TyCon
tc -> (TyCon -> Name
tyConName TyCon
tc, TyCon
tc)) [TyCon]
inferred_tcs
        ; generalized_tcs <- concatMapM (generaliseTyClDecl inferred_tc_env)
                                        kindless_decls

        ; let poly_tcs = [TyCon]
checked_tcs [TyCon] -> [TyCon] -> [TyCon]
forall a. [a] -> [a] -> [a]
++ [TyCon]
generalized_tcs
        ; traceTc "---- kcTyClGroup end ---- }" (ppr_tc_kinds poly_tcs)
        ; return (poly_tcs, kindless_names) }
  where
    ppr_tc_kinds :: [TyCon] -> SDoc
ppr_tc_kinds [TyCon]
tcs = [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat ((TyCon -> SDoc) -> [TyCon] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map TyCon -> SDoc
pp_tc [TyCon]
tcs)
    pp_tc :: TyCon -> SDoc
pp_tc TyCon
tc = Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Name
tyConName TyCon
tc) SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Type
tyConKind TyCon
tc)

type ScopedPairs = [(Name, TcTyVar)]
  -- The ScopedPairs for a TcTyCon are precisely
  --    specified-tvs ++ required-tvs
  -- You can distinguish them because there are tyConArity required-tvs

generaliseTyClDecl :: NameEnv MonoTcTyCon -> LTyClDecl GhcRn -> TcM [PolyTcTyCon]
-- See Note [Swizzling the tyvars before generaliseTcTyCon]
generaliseTyClDecl :: NameEnv TyCon -> LTyClDecl GhcRn -> TcM [TyCon]
generaliseTyClDecl NameEnv TyCon
inferred_tc_env (L SrcSpanAnnA
_ TyClDecl GhcRn
decl)
  = do { let names_in_this_decl :: [Name]
             names_in_this_decl :: [Name]
names_in_this_decl = TyClDecl GhcRn -> [Name]
tycld_names TyClDecl GhcRn
decl

       ; tc_infos <- ZonkM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
-> TcM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
forall a. ZonkM a -> TcM a
liftZonkM (ZonkM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
 -> TcM [(TyCon, SkolemInfo, [(Name, Var)], Type)])
-> ZonkM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
-> TcM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
forall a b. (a -> b) -> a -> b
$
         do { -- Extract the specified/required binders and skolemise them
            ; tc_with_tvs  <- (Name -> ZonkM (TyCon, SkolemInfo, [(Name, Var)]))
-> [Name] -> ZonkM [(TyCon, SkolemInfo, [(Name, Var)])]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM Name -> ZonkM (TyCon, SkolemInfo, [(Name, Var)])
skolemise_tc_tycon [Name]
names_in_this_decl

            -- Zonk, to manifest the side-effects of skolemisation to the swizzler
            -- NB: it's important to skolemise them all before this step. E.g.
            --         class C f where { type T (f :: k) }
            --     We only skolemise k when looking at T's binders,
            --     but k appears in f's kind in C's binders.
            ; mapM zonk_tc_tycon tc_with_tvs }

       -- Swizzle
       ; swizzled_infos <- tcAddDeclCtxt decl (swizzleTcTyConBndrs tc_infos)

       -- And finally generalise
       ; mapAndReportM generaliseTcTyCon swizzled_infos }
  where
    tycld_names :: TyClDecl GhcRn -> [Name]
    tycld_names :: TyClDecl GhcRn -> [Name]
tycld_names TyClDecl GhcRn
decl = TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl Name -> [Name] -> [Name]
forall a. a -> [a] -> [a]
: TyClDecl GhcRn -> [Name]
at_names TyClDecl GhcRn
decl

    at_names :: TyClDecl GhcRn -> [Name]
    at_names :: TyClDecl GhcRn -> [Name]
at_names (ClassDecl { tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats }) = (GenLocated SrcSpanAnnA (FamilyDecl GhcRn) -> Name)
-> [GenLocated SrcSpanAnnA (FamilyDecl GhcRn)] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map (FamilyDecl GhcRn -> IdP GhcRn
FamilyDecl GhcRn -> Name
forall (p :: Pass). FamilyDecl (GhcPass p) -> IdP (GhcPass p)
familyDeclName (FamilyDecl GhcRn -> Name)
-> (GenLocated SrcSpanAnnA (FamilyDecl GhcRn) -> FamilyDecl GhcRn)
-> GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
-> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (FamilyDecl GhcRn) -> FamilyDecl GhcRn
forall l e. GenLocated l e -> e
unLoc) [LFamilyDecl GhcRn]
[GenLocated SrcSpanAnnA (FamilyDecl GhcRn)]
ats
    at_names TyClDecl GhcRn
_ = []  -- Only class decls have associated types

    skolemise_tc_tycon :: Name -> ZonkM (TcTyCon, SkolemInfo, ScopedPairs)
    -- Zonk and skolemise the Specified and Required binders
    skolemise_tc_tycon :: Name -> ZonkM (TyCon, SkolemInfo, [(Name, Var)])
skolemise_tc_tycon Name
tc_name
      = do { let tc :: TyCon
tc = NameEnv TyCon -> Name -> TyCon
forall a. NameEnv a -> Name -> a
lookupNameEnv_NF NameEnv TyCon
inferred_tc_env Name
tc_name
                      -- This lookup should not fail
           ; skol_info <- SkolemInfoAnon -> ZonkM SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo (TyConFlavour TyCon -> Name -> SkolemInfoAnon
TyConSkol (TyCon -> TyConFlavour TyCon
tyConFlavour TyCon
tc) Name
tc_name )
           ; scoped_prs <- mapSndM (zonkAndSkolemise skol_info) (tcTyConScopedTyVars tc)
           ; return (tc, skol_info, scoped_prs) }

    zonk_tc_tycon :: (TcTyCon, SkolemInfo, ScopedPairs)
                  -> ZonkM (TcTyCon, SkolemInfo, ScopedPairs, TcKind)
    zonk_tc_tycon :: (TyCon, SkolemInfo, [(Name, Var)])
-> ZonkM (TyCon, SkolemInfo, [(Name, Var)], Type)
zonk_tc_tycon (TyCon
tc, SkolemInfo
skol_info, [(Name, Var)]
scoped_prs)
      = do { scoped_prs <- (Var -> ZonkM Var) -> [(Name, Var)] -> ZonkM [(Name, Var)]
forall (m :: * -> *) (f :: * -> *) b c a.
(Applicative m, Traversable f) =>
(b -> m c) -> f (a, b) -> m (f (a, c))
mapSndM HasDebugCallStack => Var -> ZonkM Var
Var -> ZonkM Var
zonkTcTyVarToTcTyVar [(Name, Var)]
scoped_prs
                           -- We really have to do this again, even though
                           -- we have just done zonkAndSkolemise, so that
                           -- occurrences in the /kinds/ get zonked to the skolem
           ; res_kind   <- zonkTcType (tyConResKind tc)
           ; return (tc, skol_info, scoped_prs, res_kind) }

swizzleTcTyConBndrs :: [(TcTyCon, SkolemInfo, ScopedPairs, TcKind)]
                -> TcM [(TcTyCon, SkolemInfo, ScopedPairs, TcKind)]
swizzleTcTyConBndrs :: [(TyCon, SkolemInfo, [(Name, Var)], Type)]
-> TcM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
swizzleTcTyConBndrs [(TyCon, SkolemInfo, [(Name, Var)], Type)]
tc_infos
  | ((Name, Var) -> Bool) -> [(Name, Var)] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (Name, Var) -> Bool
no_swizzle [(Name, Var)]
swizzle_prs
    -- This fast path happens almost all the time
    -- See Note [Cloning for type variable binders] in GHC.Tc.Gen.HsType
    -- "Almost all the time" means not the case of mutual recursion with
    -- polymorphic kinds.
  = do { String -> SDoc -> TcRn ()
traceTc String
"Skipping swizzleTcTyConBndrs for" ([(TyCon, SkolemInfo, [(Name, Var)], Type)] -> SDoc
forall {a} {b} {a} {d}.
Outputable a =>
[(a, b, [(a, Var)], d)] -> SDoc
ppr_infos [(TyCon, SkolemInfo, [(Name, Var)], Type)]
tc_infos)
       ; [(TyCon, SkolemInfo, [(Name, Var)], Type)]
-> TcM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return [(TyCon, SkolemInfo, [(Name, Var)], Type)]
tc_infos }

  | Bool
otherwise
  = do { [(Name, Var)] -> TcRn ()
checkForDuplicateScopedTyVars [(Name, Var)]
swizzle_prs

       ; String -> SDoc -> TcRn ()
traceTc String
"swizzleTcTyConBndrs" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"before" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(TyCon, SkolemInfo, [(Name, Var)], Type)] -> SDoc
forall {a} {b} {a} {d}.
Outputable a =>
[(a, b, [(a, Var)], d)] -> SDoc
ppr_infos [(TyCon, SkolemInfo, [(Name, Var)], Type)]
tc_infos
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"swizzle_prs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(Name, Var)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(Name, Var)]
swizzle_prs
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"after" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [(TyCon, SkolemInfo, [(Name, Var)], Type)] -> SDoc
forall {a} {b} {a} {d}.
Outputable a =>
[(a, b, [(a, Var)], d)] -> SDoc
ppr_infos [(TyCon, SkolemInfo, [(Name, Var)], Type)]
swizzled_infos ]

       ; [(TyCon, SkolemInfo, [(Name, Var)], Type)]
-> TcM [(TyCon, SkolemInfo, [(Name, Var)], Type)]
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return [(TyCon, SkolemInfo, [(Name, Var)], Type)]
swizzled_infos }

  where
    swizzled_infos :: [(TyCon, SkolemInfo, [(Name, Var)], Type)]
swizzled_infos =  [ (TyCon
tc, SkolemInfo
skol_info, (Var -> Var) -> [(Name, Var)] -> [(Name, Var)]
forall (f :: * -> *) b c a.
Functor f =>
(b -> c) -> f (a, b) -> f (a, c)
mapSnd Var -> Var
swizzle_var [(Name, Var)]
scoped_prs, Type -> Type
swizzle_ty Type
kind)
                      | (TyCon
tc, SkolemInfo
skol_info, [(Name, Var)]
scoped_prs, Type
kind) <- [(TyCon, SkolemInfo, [(Name, Var)], Type)]
tc_infos ]

    swizzle_prs :: [(Name,TyVar)]
    -- Pairs the user-specified Name with its representative TyVar
    -- See Note [Swizzling the tyvars before generaliseTcTyCon]
    swizzle_prs :: [(Name, Var)]
swizzle_prs = [ (Name, Var)
pr | (TyCon
_, SkolemInfo
_, [(Name, Var)]
prs, Type
_) <- [(TyCon, SkolemInfo, [(Name, Var)], Type)]
tc_infos, (Name, Var)
pr <- [(Name, Var)]
prs ]

    no_swizzle :: (Name,TyVar) -> Bool
    no_swizzle :: (Name, Var) -> Bool
no_swizzle (Name
nm, Var
tv) = Name
nm Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Var -> Name
tyVarName Var
tv

    ppr_infos :: [(a, b, [(a, Var)], d)] -> SDoc
ppr_infos [(a, b, [(a, Var)], d)]
infos = [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
tc SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Var] -> SDoc
pprTyVars (((a, Var) -> Var) -> [(a, Var)] -> [Var]
forall a b. (a -> b) -> [a] -> [b]
map (a, Var) -> Var
forall a b. (a, b) -> b
snd [(a, Var)]
prs)
                           | (a
tc, b
_, [(a, Var)]
prs, d
_) <- [(a, b, [(a, Var)], d)]
infos ]

    -------------- The swizzler ------------
    -- This does a deep traverse, simply doing a
    -- Name-to-Name change, governed by swizzle_env
    -- The 'swap' is what gets from the representative TyVar
    -- back to the original user-specified Name
    swizzle_env :: VarEnv Name
swizzle_env = [(Var, Name)] -> VarEnv Name
forall a. [(Var, a)] -> VarEnv a
mkVarEnv (((Name, Var) -> (Var, Name)) -> [(Name, Var)] -> [(Var, Name)]
forall a b. (a -> b) -> [a] -> [b]
map (Name, Var) -> (Var, Name)
forall a b. (a, b) -> (b, a)
swap [(Name, Var)]
swizzle_prs)

    swizzleMapper :: TyCoMapper () Identity
    swizzleMapper :: TyCoMapper () Identity
swizzleMapper = TyCoMapper { tcm_tyvar :: () -> Var -> Identity Type
tcm_tyvar = () -> Var -> Identity Type
forall {m :: * -> *} {p}. Monad m => p -> Var -> m Type
swizzle_tv
                               , tcm_covar :: () -> Var -> Identity Coercion
tcm_covar = () -> Var -> Identity Coercion
forall {m :: * -> *} {p}. Monad m => p -> Var -> m Coercion
swizzle_cv
                               , tcm_hole :: () -> CoercionHole -> Identity Coercion
tcm_hole  = () -> CoercionHole -> Identity Coercion
forall {a} {p} {a}. Outputable a => p -> a -> a
swizzle_hole
                               , tcm_tycobinder :: forall r.
()
-> Var -> ForAllTyFlag -> (() -> Var -> Identity r) -> Identity r
tcm_tycobinder = ()
-> Var -> ForAllTyFlag -> (() -> Var -> Identity r) -> Identity r
forall r.
()
-> Var -> ForAllTyFlag -> (() -> Var -> Identity r) -> Identity r
swizzle_bndr
                               , tcm_tycon :: TyCon -> Identity TyCon
tcm_tycon      = TyCon -> Identity TyCon
forall {a} {a}. Outputable a => a -> a
swizzle_tycon }
    swizzle_hole :: p -> a -> a
swizzle_hole  p
_ a
hole = String -> SDoc -> a
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"swizzle_hole" (a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
hole)
       -- These types are pre-zonked
    swizzle_tycon :: a -> a
swizzle_tycon a
tc = String -> SDoc -> a
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"swizzle_tc" (a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
tc)
       -- TcTyCons can't appear in kinds (yet)
    swizzle_tv :: p -> Var -> m Type
swizzle_tv p
_ Var
tv = Type -> m Type
forall a. a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return (Var -> Type
mkTyVarTy (Var -> Var
swizzle_var Var
tv))
    swizzle_cv :: p -> Var -> m Coercion
swizzle_cv p
_ Var
cv = Coercion -> m Coercion
forall a. a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return (Var -> Coercion
mkCoVarCo (Var -> Var
swizzle_var Var
cv))

    swizzle_bndr :: ()
      -> TyCoVar
      -> ForAllTyFlag
      -> (() -> TyCoVar -> Identity r)
      -> Identity r
    swizzle_bndr :: forall r.
()
-> Var -> ForAllTyFlag -> (() -> Var -> Identity r) -> Identity r
swizzle_bndr ()
_ Var
tcv ForAllTyFlag
_ () -> Var -> Identity r
k
      = () -> Var -> Identity r
k () (Var -> Var
swizzle_var Var
tcv)

    swizzle_var :: Var -> Var
    swizzle_var :: Var -> Var
swizzle_var Var
v
      | Just Name
nm <- VarEnv Name -> Var -> Maybe Name
forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv VarEnv Name
swizzle_env Var
v
      = (Type -> Type) -> Var -> Var
updateVarType Type -> Type
swizzle_ty (Var
v Var -> Name -> Var
`setVarName` Name
nm)
      | Bool
otherwise
      = (Type -> Type) -> Var -> Var
updateVarType Type -> Type
swizzle_ty Var
v

    (Type -> Identity Type
map_type, ThetaType -> Identity ThetaType
_, Coercion -> Identity Coercion
_, [Coercion] -> Identity [Coercion]
_) = TyCoMapper () Identity
-> (Type -> Identity Type, ThetaType -> Identity ThetaType,
    Coercion -> Identity Coercion, [Coercion] -> Identity [Coercion])
forall (m :: * -> *).
Monad m =>
TyCoMapper () m
-> (Type -> m Type, ThetaType -> m ThetaType,
    Coercion -> m Coercion, [Coercion] -> m [Coercion])
mapTyCo TyCoMapper () Identity
swizzleMapper
    swizzle_ty :: Type -> Type
swizzle_ty Type
ty = Identity Type -> Type
forall a. Identity a -> a
runIdentity (Type -> Identity Type
map_type Type
ty)


generaliseTcTyCon :: (MonoTcTyCon, SkolemInfo, ScopedPairs, TcKind) -> TcM PolyTcTyCon
generaliseTcTyCon :: (TyCon, SkolemInfo, [(Name, Var)], Type) -> TcRn TyCon
generaliseTcTyCon (TyCon
tc, SkolemInfo
skol_info, [(Name, Var)]
scoped_prs, Type
tc_res_kind)
  -- The scoped_prs are fully zonked skolem TcTyVars
  -- And tc_res_kind is fully zonked too
  -- See Note [Required, Specified, and Inferred for types]
  = SrcSpan -> TcRn TyCon -> TcRn TyCon
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (TyCon -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan TyCon
tc) (TcRn TyCon -> TcRn TyCon) -> TcRn TyCon -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    TyCon -> TcRn TyCon -> TcRn TyCon
forall a. TyCon -> TcM a -> TcM a
addTyConCtxt TyCon
tc (TcRn TyCon -> TcRn TyCon) -> TcRn TyCon -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    do { -- Step 1: Separate Specified from Required variables
         -- NB: spec_req_tvs = spec_tvs ++ req_tvs
         --     And req_tvs is 1-1 with tyConTyVars
         --     See Note [Scoped tyvars in a TcTyCon] in GHC.Core.TyCon
       ; let spec_req_tvs :: [Var]
spec_req_tvs        = ((Name, Var) -> Var) -> [(Name, Var)] -> [Var]
forall a b. (a -> b) -> [a] -> [b]
map (Name, Var) -> Var
forall a b. (a, b) -> b
snd [(Name, Var)]
scoped_prs
             n_spec :: Int
n_spec              = [Var] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Var]
spec_req_tvs Int -> Int -> Int
forall a. Num a => a -> a -> a
- TyCon -> Int
tyConArity TyCon
tc
             ([Var]
spec_tvs, [Var]
req_tvs) = Int -> [Var] -> ([Var], [Var])
forall a. Int -> [a] -> ([a], [a])
splitAt Int
n_spec [Var]
spec_req_tvs
             sorted_spec_tvs :: [Var]
sorted_spec_tvs     = [Var] -> [Var]
scopedSort [Var]
spec_tvs
                 -- NB: We can't do the sort until we've zonked
                 --     Maintain the L-R order of scoped_tvs

       -- Step 2a: find all the Inferred variables we want to quantify over
       ; dvs1 <- ThetaType -> TcM CandidatesQTvs
candidateQTyVarsOfKinds (ThetaType -> TcM CandidatesQTvs)
-> ThetaType -> TcM CandidatesQTvs
forall a b. (a -> b) -> a -> b
$
                 (Type
tc_res_kind Type -> ThetaType -> ThetaType
forall a. a -> [a] -> [a]
: (Var -> Type) -> [Var] -> ThetaType
forall a b. (a -> b) -> [a] -> [b]
map Var -> Type
tyVarKind [Var]
spec_req_tvs)
       ; let dvs2 = CandidatesQTvs
dvs1 CandidatesQTvs -> [Var] -> CandidatesQTvs
`delCandidates` [Var]
spec_req_tvs

       -- Step 2b: quantify, mainly meaning skolemise the free variables
       -- Returned 'inferred' are scope-sorted and skolemised
       ; inferred <- quantifyTyVars skol_info DefaultNonStandardTyVars dvs2

       ; traceTc "generaliseTcTyCon: pre zonk"
           (vcat [ text "tycon =" <+> ppr tc
                 , text "spec_req_tvs =" <+> pprTyVars spec_req_tvs
                 , text "tc_res_kind =" <+> ppr tc_res_kind
                 , text "dvs1 =" <+> ppr dvs1
                 , text "inferred =" <+> pprTyVars inferred ])

       -- Step 3: Final zonk: quantifyTyVars may have done some defaulting
       ; (inferred, sorted_spec_tvs,req_tvs,tc_res_kind) <- liftZonkM $
          do { inferred        <- zonkTcTyVarsToTcTyVars inferred
             ; sorted_spec_tvs <- zonkTcTyVarsToTcTyVars sorted_spec_tvs
             ; req_tvs         <- zonkTcTyVarsToTcTyVars req_tvs
             ; tc_res_kind     <- zonkTcType             tc_res_kind
             ; return (inferred, sorted_spec_tvs, req_tvs, tc_res_kind) }

       ; traceTc "generaliseTcTyCon: post zonk" $
         vcat [ text "tycon =" <+> ppr tc
              , text "inferred =" <+> pprTyVars inferred
              , text "spec_req_tvs =" <+> pprTyVars spec_req_tvs
              , text "sorted_spec_tvs =" <+> pprTyVars sorted_spec_tvs
              , text "req_tvs =" <+> ppr req_tvs ]

       -- Step 4: Make the TyConBinders.
       ; let dep_fv_set     = CandidatesQTvs -> VarSet
candidateKindVars CandidatesQTvs
dvs1
             inferred_tcbs  = ForAllTyFlag -> [Var] -> [TyConBinder]
mkNamedTyConBinders ForAllTyFlag
Inferred [Var]
inferred
             specified_tcbs = ForAllTyFlag -> [Var] -> [TyConBinder]
mkNamedTyConBinders ForAllTyFlag
Specified [Var]
sorted_spec_tvs
             required_tcbs  = (Var -> TyConBinder) -> [Var] -> [TyConBinder]
forall a b. (a -> b) -> [a] -> [b]
map (VarSet -> Var -> TyConBinder
mkRequiredTyConBinder VarSet
dep_fv_set) [Var]
req_tvs

       -- Step 5: Assemble the final list.
             all_tcbs = [[TyConBinder]] -> [TyConBinder]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [ [TyConBinder]
inferred_tcbs
                               , [TyConBinder]
specified_tcbs
                               , [TyConBinder]
required_tcbs ]
             flav = TyCon -> TyConFlavour TyCon
tyConFlavour TyCon
tc

       -- Eta expand
       ; (eta_tcbs, tc_res_kind) <- etaExpandAlgTyCon flav skol_info all_tcbs tc_res_kind

       -- Step 6: Make the result TcTyCon
       ; let final_tcbs = [TyConBinder]
all_tcbs [TyConBinder] -> [TyConBinder] -> [TyConBinder]
forall a. [a] -> [a] -> [a]
`chkAppend` [TyConBinder]
eta_tcbs
             tycon = Name
-> [TyConBinder]
-> Type
-> [(Name, Var)]
-> Bool
-> TyConFlavour TyCon
-> TyCon
mkTcTyCon (TyCon -> Name
tyConName TyCon
tc)
                               [TyConBinder]
final_tcbs Type
tc_res_kind
                               ([Var] -> [(Name, Var)]
mkTyVarNamePairs ([Var]
sorted_spec_tvs [Var] -> [Var] -> [Var]
forall a. [a] -> [a] -> [a]
++ [Var]
req_tvs))
                               Bool
True {- it's generalised now -}
                               TyConFlavour TyCon
flav

       ; traceTc "generaliseTcTyCon done" $
         vcat [ text "tycon =" <+> ppr tc
              , text "tc_res_kind =" <+> ppr tc_res_kind
              , text "dep_fv_set =" <+> ppr dep_fv_set
              , text "inferred_tcbs =" <+> ppr inferred_tcbs
              , text "specified_tcbs =" <+> ppr specified_tcbs
              , text "required_tcbs =" <+> ppr required_tcbs
              , text "final_tcbs =" <+> ppr final_tcbs ]

       -- Step 7: Check for validity.
       -- We do this here because we're about to put the tycon into the
       -- the environment, and we don't want anything malformed there
       ; checkTyConTelescope tycon

       ; return tycon }

{- Note [Required, Specified, and Inferred for types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Each forall'd type variable in a type or kind is one of

  * Required: an argument must be provided at every call site

  * Specified: the argument can be inferred at call sites, but
    may be instantiated with visible type/kind application

  * Inferred: the argument must be inferred at call sites; it
    is unavailable for use with visible type/kind application.

Why have Inferred at all? Because we just can't make user-facing
promises about the ordering of some variables. These might swizzle
around even between minor released. By forbidding visible type
application, we ensure users aren't caught unawares.

Go read Note [VarBndrs, ForAllTyBinders, TyConBinders, and visibility] in GHC.Core.TyCo.Rep.

The question for this Note is this:
   given a TyClDecl, how are its quantified type variables classified?
Much of the debate is memorialized in #15743.

Here is our design choice. When inferring the ordering of variables
for a TyCl declaration (that is, for those variables that the user
has not specified the order with an explicit `forall`), we use the
following order:

 1. Inferred variables
 2. Specified variables; in the left-to-right order in which
    the user wrote them, modified by scopedSort (see below)
    to put them in dependency order.
 3. Required variables before a top-level ::
 4. All variables after a top-level ::

If this ordering does not make a valid telescope, we reject the definition.

Example:
  data SameKind :: k -> k -> *
  data Bad a (c :: Proxy b) (d :: Proxy a) (x :: SameKind b d)

For Bad:
  - a, c, d, x are Required; they are explicitly listed by the user
    as the positional arguments of Bad
  - b is Specified; it appears explicitly in a kind signature
  - k, the kind of a, is Inferred; it is not mentioned explicitly at all

Putting variables in the order Inferred, Specified, Required
gives us this telescope:
  Inferred:  k
  Specified: b : Proxy a
  Required : (a : k) (c : Proxy b) (d : Proxy a) (x : SameKind b d)

But this order is ill-scoped, because b's kind mentions a, which occurs
after b in the telescope. So we reject Bad.

Associated types
~~~~~~~~~~~~~~~~
For associated types everything above is determined by the
associated-type declaration alone, ignoring the class header.
Here is an example (#15592)
  class C (a :: k) b where
    type F (x :: b a)

In the kind of C, 'k' is Specified.  But what about F?
In the kind of F,

 * Should k be Inferred or Specified?  It's Specified for C,
   but not mentioned in F's declaration.

 * In which order should the Specified variables a and b occur?
   It's clearly 'a' then 'b' in C's declaration, but the L-R ordering
   in F's declaration is 'b' then 'a'.

In both cases we make the choice by looking at F's declaration alone,
so it gets the kind
   F :: forall {k}. forall b a. b a -> Type

How it works
~~~~~~~~~~~~
These design choices are implemented by two completely different code
paths for

  * Declarations with a standalone kind signature or a complete user-specified
    kind signature (CUSK). Handled by the kcCheckDeclHeader.

  * Declarations without a kind signature (standalone or CUSK) are handled by
    kcInferDeclHeader; see Note [Inferring kinds for type declarations].

Note that neither code path worries about point (4) above, as this
is nicely handled by not mangling the res_kind. (Mangling res_kinds is done
*after* all this stuff, in tcDataDefn's call to etaExpandAlgTyCon.)

We can tell Inferred apart from Specified by looking at the scoped
tyvars; Specified are always included there.

Design alternatives
~~~~~~~~~~~~~~~~~~~
* For associated types we considered putting the class variables
  before the local variables, in a nod to the treatment for class
  methods. But it got too complicated; see #15592, comment:21ff.

* We rigidly require the ordering above, even though we could be much more
  permissive. Relevant musings are at
  https://gitlab.haskell.org/ghc/ghc/issues/15743#note_161623
  The bottom line conclusion is that, if the user wants a different ordering,
  then can specify it themselves, and it is better to be predictable and dumb
  than clever and capricious.

  I (Richard) conjecture we could be fully permissive, allowing all classes
  of variables to intermix. We would have to augment ScopedSort to refuse to
  reorder Required variables (or check that it wouldn't have). But this would
  allow more programs. See #15743 for examples. Interestingly, Idris seems
  to allow this intermixing. The intermixing would be fully specified, in that
  we can be sure that inference wouldn't change between versions. However,
  would users be able to predict it? That I cannot answer.

Test cases (and tickets) relevant to these design decisions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  T15591*
  T15592*
  T15743*

Note [Inferring kinds for type declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This note deals with /inference/ for type declarations
that do not have a CUSK or a SAKS.  Consider
  data T (a :: k1) k2 (x :: k2) = MkT (S a k2 x)
  data S (b :: k3) k4 (y :: k4) = MkS (T b k4 y)

We do kind inference as follows:

* Step 1: inferInitialKinds, and in particular kcInferDeclHeader.
  Make a unification variable for each of the Required and Specified
  type variables in the header.

  Record the connection between the Names the user wrote and the
  fresh unification variables in the tcTyConScopedTyVars field
  of the TcTyCon we are making
      [ (a,  aa)
      , (k1, kk1)
      , (k2, kk2)
      , (x,  xx) ]
  (I'm using the convention that double letter like 'aa' or 'kk'
  mean a unification variable.)

  These unification variables
    - Are TyVarTvs: that is, unification variables that can
      unify only with other type variables.
      See Note [TyVarTv] in GHC.Tc.Utils.TcMType

    - Have complete fresh Names; see GHC.Tc.Utils.TcMType
      Note [Unification variables need fresh Names]

  Assign initial monomorphic kinds to S, T
          T :: kk1 -> * -> kk2 -> *
          S :: kk3 -> * -> kk4 -> *

* Step 2: kcTyClDecl. Extend the environment with a TcTyCon for S and
  T, with these monomorphic kinds.  Now kind-check the declarations,
  and solve the resulting equalities.  The goal here is to discover
  constraints on all these unification variables.

  Here we find that kk1 := kk3, and kk2 := kk4.

  This is why we can't use skolems for kk1 etc; they have to
  unify with each other.

* Step 3: generaliseTcTyCon. Generalise each TyCon in turn.
  We find the free variables of the kind, skolemise them,
  sort them out into Inferred/Required/Specified (see the above
  Note [Required, Specified, and Inferred for types]),
  and perform some validity checks.

  This makes the utterly-final TyConBinders for the TyCon.

  All this is very similar at the level of terms: see GHC.Tc.Gen.Bind
  Note [Quantified variables in partial type signatures]

  But there are some tricky corners: Note [Tricky scoping in generaliseTcTyCon]

* Step 4.  Extend the type environment with a TcTyCon for S and T, now
  with their utterly-final polymorphic kinds (needed for recursive
  occurrences of S, T).  Now typecheck the declarations, and build the
  final AlgTyCon for S and T resp.

The first three steps are in kcTyClGroup; the fourth is in
tcTyClDecls.

There are some wrinkles

* Do not default TyVarTvs.  We always want to kind-generalise over
  TyVarTvs, and /not/ default them to Type. By definition a TyVarTv is
  not allowed to unify with a type; it must stand for a type
  variable. Hence the check in GHC.Tc.Solver.defaultTyVarTcS, and
  GHC.Tc.Utils.TcMType.defaultTyVar.  Here's another example (#14555):
     data Exp :: [TYPE rep] -> TYPE rep -> Type where
        Lam :: Exp (a:xs) b -> Exp xs (a -> b)
  We want to kind-generalise over the 'rep' variable.
  #14563 is another example.

* Duplicate type variables. Consider #11203
    data SameKind :: k -> k -> *
    data Q (a :: k1) (b :: k2) c = MkQ (SameKind a b)
  Here we will unify k1 with k2, but this time doing so is an error,
  because k1 and k2 are bound in the same declaration.

  We spot this during validity checking (checkForDuplicateScopeTyVars),
  in generaliseTcTyCon.

* Required arguments.  Even the Required arguments should be made
  into TyVarTvs, not skolems.  Consider
    data T k (a :: k)
  Here, k is a Required, dependent variable. For uniformity, it is helpful
  to have k be a TyVarTv, in parallel with other dependent variables.

* Duplicate skolemisation is expected.  When generalising in Step 3,
  we may find that one of the variables we want to quantify has
  already been skolemised.  For example, suppose we have already
  generalise S. When we come to T we'll find that kk1 (now the same as
  kk3) has already been skolemised.

  That's fine -- but it means that
    a) when collecting quantification candidates, in
       candidateQTyVarsOfKind, we must collect skolems
    b) quantifyTyVars should be a no-op on such a skolem

Note [Tricky scoping in generaliseTcTyCon]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider #16342
  class C (a::ka) x where
    cop :: D a x => x -> Proxy a -> Proxy a
    cop _ x = x :: Proxy (a::ka)

  class D (b::kb) y where
    dop :: C b y => y -> Proxy b -> Proxy b
    dop _ x = x :: Proxy (b::kb)

C and D are mutually recursive, by the time we get to
generaliseTcTyCon we'll have unified kka := kkb.

But when typechecking the default declarations for 'cop' and 'dop' in
tcDlassDecl2 we need {a, ka} and {b, kb} respectively to be in scope.
But at that point all we have is the utterly-final Class itself.

Conclusion: the classTyVars of a class must have the same Name as
that originally assigned by the user.  In our example, C must have
classTyVars {a, ka, x} while D has classTyVars {a, kb, y}.  Despite
the fact that kka and kkb got unified!

We achieve this sleight of hand in generaliseTcTyCon, using
the specialised function zonkRecTyVarBndrs.  We make the call
   zonkRecTyVarBndrs [ka,a,x] [kkb,aa,xxx]
where the [ka,a,x] are the Names originally assigned by the user, and
[kkb,aa,xx] are the corresponding (post-zonking, skolemised) TcTyVars.
zonkRecTyVarBndrs builds a recursive ZonkEnv that binds
   kkb :-> (ka :: <zonked kind of kkb>)
   aa  :-> (a  :: <konked kind of aa>)
   etc
That is, it maps each skolemised TcTyVars to the utterly-final
TyVar to put in the class, with its correct user-specified name.
When generalising D we'll do the same thing, but the ZonkEnv will map
   kkb :-> (kb :: <zonked kind of kkb>)
   bb  :-> (b  :: <konked kind of bb>)
   etc
Note that 'kkb' again appears in the domain of the mapping, but this
time mapped to 'kb'.  That's how C and D end up with differently-named
final TyVars despite the fact that we unified kka:=kkb

zonkRecTyVarBndrs we need to do knot-tying because of the need to
apply this same substitution to the kind of each.

Note [Inferring visible dependent quantification]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider

  data T k :: k -> Type where
    MkT1 :: T Type Int
    MkT2 :: T (Type -> Type) Maybe

This looks like it should work. However, it is polymorphically recursive,
as the uses of T in the constructor types specialize the k in the kind
of T. This trips up our dear users (#17131, #17541), and so we add
a "landmark" context (which cannot be suppressed) whenever we
spot inferred visible dependent quantification (VDQ).

It's hard to know when we've actually been tripped up by polymorphic recursion
specifically, so we just include a note to users whenever we infer VDQ. The
testsuite did not show up a single spurious inclusion of this message.

The context is added in addVDQNote, which looks for a visible
TyConBinder that also appears in the TyCon's kind. (I first looked at
the kind for a visible, dependent quantifier, but
  Note [No polymorphic recursion in type decls]
in GHC.Tc.Gen.HsType defeats that approach.) addVDQNote is used in
kcTyClDecl, which is used only when inferring the kind of a tycon
(never with a CUSK or SAKS).

Once upon a time, I (Richard E) thought that the tycon-kind could
not be a forall-type. But this is wrong: data T :: forall k. k -> Type
(with -XNoCUSKs) could end up here. And this is all OK.
-}

--------------
tcExtendKindEnvWithTyCons :: [TcTyCon] -> TcM a -> TcM a
tcExtendKindEnvWithTyCons :: forall r. [TyCon] -> TcM r -> TcM r
tcExtendKindEnvWithTyCons [TyCon]
tcs
  = [(Name, TcTyThing)] -> TcM a -> TcM a
forall r. [(Name, TcTyThing)] -> TcM r -> TcM r
tcExtendKindEnvList [ (TyCon -> Name
tyConName TyCon
tc, TyCon -> TcTyThing
ATcTyCon TyCon
tc) | TyCon
tc <- [TyCon]
tcs ]

--------------
mkPromotionErrorEnv :: [LTyClDecl GhcRn] -> TcTypeEnv
-- Maps each tycon/datacon to a suitable promotion error
--    tc :-> APromotionErr TyConPE
--    dc :-> APromotionErr RecDataConPE
--    See Note [Recursion and promoting data constructors]

mkPromotionErrorEnv :: [LTyClDecl GhcRn] -> NameEnv TcTyThing
mkPromotionErrorEnv [LTyClDecl GhcRn]
decls
  = (GenLocated SrcSpanAnnA (TyClDecl GhcRn)
 -> NameEnv TcTyThing -> NameEnv TcTyThing)
-> NameEnv TcTyThing
-> [GenLocated SrcSpanAnnA (TyClDecl GhcRn)]
-> NameEnv TcTyThing
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing
forall a. NameEnv a -> NameEnv a -> NameEnv a
plusNameEnv (NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing)
-> (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> NameEnv TcTyThing)
-> GenLocated SrcSpanAnnA (TyClDecl GhcRn)
-> NameEnv TcTyThing
-> NameEnv TcTyThing
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TyClDecl GhcRn -> NameEnv TcTyThing
mk_prom_err_env (TyClDecl GhcRn -> NameEnv TcTyThing)
-> (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn)
-> GenLocated SrcSpanAnnA (TyClDecl GhcRn)
-> NameEnv TcTyThing
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn
forall l e. GenLocated l e -> e
unLoc)
          NameEnv TcTyThing
forall a. NameEnv a
emptyNameEnv [LTyClDecl GhcRn]
[GenLocated SrcSpanAnnA (TyClDecl GhcRn)]
decls

mk_prom_err_env :: TyClDecl GhcRn -> TcTypeEnv
mk_prom_err_env :: TyClDecl GhcRn -> NameEnv TcTyThing
mk_prom_err_env (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
nm, tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats })
  = Name -> TcTyThing -> NameEnv TcTyThing
forall a. Name -> a -> NameEnv a
unitNameEnv Name
nm (PromotionErr -> TcTyThing
APromotionErr PromotionErr
ClassPE)
    NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv`
    [(Name, TcTyThing)] -> NameEnv TcTyThing
forall a. [(Name, a)] -> NameEnv a
mkNameEnv [ (FamilyDecl GhcRn -> IdP GhcRn
forall (p :: Pass). FamilyDecl (GhcPass p) -> IdP (GhcPass p)
familyDeclName FamilyDecl GhcRn
at, PromotionErr -> TcTyThing
APromotionErr PromotionErr
TyConPE)
              | L SrcSpanAnnA
_ FamilyDecl GhcRn
at <- [LFamilyDecl GhcRn]
[GenLocated SrcSpanAnnA (FamilyDecl GhcRn)]
ats ]

mk_prom_err_env (DataDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
name
                          , tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn { dd_cons :: forall pass. HsDataDefn pass -> DataDefnCons (LConDecl pass)
dd_cons = DataDefnCons (LConDecl GhcRn)
cons } })
  = Name -> TcTyThing -> NameEnv TcTyThing
forall a. Name -> a -> NameEnv a
unitNameEnv Name
name (PromotionErr -> TcTyThing
APromotionErr PromotionErr
TyConPE)
    NameEnv TcTyThing -> NameEnv TcTyThing -> NameEnv TcTyThing
forall a. NameEnv a -> NameEnv a -> NameEnv a
`plusNameEnv`
    [(Name, TcTyThing)] -> NameEnv TcTyThing
forall a. [(Name, a)] -> NameEnv a
mkNameEnv [ (Name
con, PromotionErr -> TcTyThing
APromotionErr PromotionErr
conPE)
              | L SrcSpanAnnA
_ ConDecl GhcRn
con' <- DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn))
-> [GenLocated SrcSpanAnnA (ConDecl GhcRn)]
forall a. DataDefnCons a -> [a]
forall (t :: * -> *) a. Foldable t => t a -> [a]
toList DataDefnCons (LConDecl GhcRn)
DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn))
cons
              , L SrcSpanAnnN
_ Name
con  <- ConDecl GhcRn -> [LocatedN Name]
getConNames ConDecl GhcRn
con' ]
  where
    -- In a "type data" declaration, the constructors are at the type level.
    -- See Note [Type data declarations] in GHC.Rename.Module.
    conPE :: PromotionErr
conPE
      | DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn)) -> Bool
forall a. DataDefnCons a -> Bool
isTypeDataDefnCons DataDefnCons (LConDecl GhcRn)
DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn))
cons = PromotionErr
TyConPE
      | Bool
otherwise = PromotionErr
RecDataConPE

mk_prom_err_env TyClDecl GhcRn
decl
  = Name -> TcTyThing -> NameEnv TcTyThing
forall a. Name -> a -> NameEnv a
unitNameEnv (TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl) (PromotionErr -> TcTyThing
APromotionErr PromotionErr
TyConPE)
    -- Works for family declarations too

--------------
inferInitialKinds :: [LTyClDecl GhcRn] -> TcM [MonoTcTyCon]
-- Returns a TcTyCon for each TyCon bound by the decls,
-- each with its initial kind

inferInitialKinds :: [LTyClDecl GhcRn] -> TcM [TyCon]
inferInitialKinds [LTyClDecl GhcRn]
decls
  = do { String -> SDoc -> TcRn ()
traceTc String
"inferInitialKinds {" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [IdGhcP 'Renamed] -> SDoc
forall a. Outputable a => a -> SDoc
ppr ((GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> IdGhcP 'Renamed)
-> [GenLocated SrcSpanAnnA (TyClDecl GhcRn)] -> [IdGhcP 'Renamed]
forall a b. (a -> b) -> [a] -> [b]
map (TyClDecl GhcRn -> IdP GhcRn
TyClDecl GhcRn -> IdGhcP 'Renamed
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (TyClDecl GhcRn -> IdGhcP 'Renamed)
-> (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn)
-> GenLocated SrcSpanAnnA (TyClDecl GhcRn)
-> IdGhcP 'Renamed
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn
forall l e. GenLocated l e -> e
unLoc) [LTyClDecl GhcRn]
[GenLocated SrcSpanAnnA (TyClDecl GhcRn)]
decls)
       ; tcs <- (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TcM [TyCon])
-> [GenLocated SrcSpanAnnA (TyClDecl GhcRn)] -> TcM [TyCon]
forall (m :: * -> *) (f :: * -> *) a b.
(Monad m, Traversable f) =>
(a -> m [b]) -> f a -> m [b]
concatMapM GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TcM [TyCon]
infer_initial_kind [LTyClDecl GhcRn]
[GenLocated SrcSpanAnnA (TyClDecl GhcRn)]
decls
       ; traceTc "inferInitialKinds done }" empty
       ; return tcs }
  where
    infer_initial_kind :: GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TcM [TyCon]
infer_initial_kind = (TyClDecl GhcRn -> TcM [TyCon])
-> GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TcM [TyCon]
forall t a b. HasLoc t => (a -> TcM b) -> GenLocated t a -> TcM b
addLocM (InitialKindStrategy -> TyClDecl GhcRn -> TcM [TyCon]
getInitialKind InitialKindStrategy
InitialKindInfer)

-- Check type/class declarations against their standalone kind signatures or
-- CUSKs, producing a generalized TcTyCon for each.
checkInitialKinds :: [(LTyClDecl GhcRn, SAKS_or_CUSK)] -> TcM [PolyTcTyCon]
checkInitialKinds :: [(LTyClDecl GhcRn, SAKS_or_CUSK)] -> TcM [TyCon]
checkInitialKinds [(LTyClDecl GhcRn, SAKS_or_CUSK)]
decls
  = do { String -> SDoc -> TcRn ()
traceTc String
"checkInitialKinds {" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [(IdGhcP 'Renamed, SAKS_or_CUSK)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr ((GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> IdGhcP 'Renamed)
-> [(GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)]
-> [(IdGhcP 'Renamed, SAKS_or_CUSK)]
forall (f :: * -> *) a c b.
Functor f =>
(a -> c) -> f (a, b) -> f (c, b)
mapFst (TyClDecl GhcRn -> IdP GhcRn
TyClDecl GhcRn -> IdGhcP 'Renamed
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName (TyClDecl GhcRn -> IdGhcP 'Renamed)
-> (GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn)
-> GenLocated SrcSpanAnnA (TyClDecl GhcRn)
-> IdGhcP 'Renamed
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (TyClDecl GhcRn) -> TyClDecl GhcRn
forall l e. GenLocated l e -> e
unLoc) [(LTyClDecl GhcRn, SAKS_or_CUSK)]
[(GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)]
decls)
       ; tcs <- ((GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)
 -> TcM [TyCon])
-> [(GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)]
-> TcM [TyCon]
forall (m :: * -> *) (f :: * -> *) a b.
(Monad m, Traversable f) =>
(a -> m [b]) -> f a -> m [b]
concatMapM (GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)
-> TcM [TyCon]
forall {t}.
HasLoc t =>
(GenLocated t (TyClDecl GhcRn), SAKS_or_CUSK) -> TcM [TyCon]
check_initial_kind [(LTyClDecl GhcRn, SAKS_or_CUSK)]
[(GenLocated SrcSpanAnnA (TyClDecl GhcRn), SAKS_or_CUSK)]
decls
       ; traceTc "checkInitialKinds done }" empty
       ; return tcs }
  where
    check_initial_kind :: (GenLocated t (TyClDecl GhcRn), SAKS_or_CUSK) -> TcM [TyCon]
check_initial_kind (GenLocated t (TyClDecl GhcRn)
ldecl, SAKS_or_CUSK
msig) =
      (TyClDecl GhcRn -> TcM [TyCon])
-> GenLocated t (TyClDecl GhcRn) -> TcM [TyCon]
forall t a b. HasLoc t => (a -> TcM b) -> GenLocated t a -> TcM b
addLocM (InitialKindStrategy -> TyClDecl GhcRn -> TcM [TyCon]
getInitialKind (SAKS_or_CUSK -> InitialKindStrategy
InitialKindCheck SAKS_or_CUSK
msig)) GenLocated t (TyClDecl GhcRn)
ldecl

-- | Get the initial kind of a TyClDecl, either generalized or non-generalized,
-- depending on the 'InitialKindStrategy'.
getInitialKind :: InitialKindStrategy -> TyClDecl GhcRn -> TcM [TcTyCon]

-- Allocate a fresh kind variable for each TyCon and Class
-- For each tycon, return a TcTyCon with kind k
-- where k is the kind of tc, derived from the LHS
--         of the definition (and probably including
--         kind unification variables)
--      Example: data T a b = ...
--      return (T, kv1 -> kv2 -> kv3)
--
-- This pass deals with (ie incorporates into the kind it produces)
--   * The kind signatures on type-variable binders
--   * The result kinds signature on a TyClDecl
--
-- No family instances are passed to checkInitialKinds/inferInitialKinds
getInitialKind :: InitialKindStrategy -> TyClDecl GhcRn -> TcM [TyCon]
getInitialKind InitialKindStrategy
strategy
    (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
name
               , tcdTyVars :: forall pass. TyClDecl pass -> LHsQTyVars pass
tcdTyVars = LHsQTyVars GhcRn
ktvs
               , tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats })
  = do { cls_tc <- InitialKindStrategy
-> Name
-> TyConFlavour TyCon
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
strategy Name
name TyConFlavour TyCon
forall tc. TyConFlavour tc
ClassFlavour LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
                ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> ContextKind
TheKind Type
constraintKind)
            -- See Note [Don't process associated types in getInitialKind]

       ; at_tcs <- tcExtendTyVarEnv (tyConTyVars cls_tc) $
                      mapM (addLocM (getAssocFamInitialKind cls_tc)) ats
       ; return (cls_tc : at_tcs) }
  where
    getAssocFamInitialKind :: TyCon -> FamilyDecl GhcRn -> TcRn TyCon
getAssocFamInitialKind TyCon
cls =
      case InitialKindStrategy
strategy of
        InitialKindStrategy
InitialKindInfer   -> Maybe TyCon -> FamilyDecl GhcRn -> TcRn TyCon
get_fam_decl_initial_kind (TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
cls)
        InitialKindCheck SAKS_or_CUSK
_ -> TyCon -> FamilyDecl GhcRn -> TcRn TyCon
check_initial_kind_assoc_fam TyCon
cls

getInitialKind InitialKindStrategy
strategy
    (DataDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
name
              , tcdTyVars :: forall pass. TyClDecl pass -> LHsQTyVars pass
tcdTyVars = LHsQTyVars GhcRn
ktvs
              , tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn { dd_kindSig :: forall pass. HsDataDefn pass -> Maybe (LHsKind pass)
dd_kindSig = Maybe (LHsKind GhcRn)
m_sig, dd_cons :: forall pass. HsDataDefn pass -> DataDefnCons (LConDecl pass)
dd_cons = DataDefnCons (LConDecl GhcRn)
cons } })
  = do  { let flav :: TyConFlavour TyCon
flav = NewOrData -> TyConFlavour TyCon
forall tc. NewOrData -> TyConFlavour tc
newOrDataToFlavour (DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn)) -> NewOrData
forall a. DataDefnCons a -> NewOrData
dataDefnConsNewOrData DataDefnCons (LConDecl GhcRn)
DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn))
cons)
              ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
DataKindCtxt Name
name
        ; tc <- InitialKindStrategy
-> Name
-> TyConFlavour TyCon
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
strategy Name
name TyConFlavour TyCon
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
                case Maybe (LHsKind GhcRn)
m_sig of
                  Just LHsKind GhcRn
ksig -> Type -> ContextKind
TheKind (Type -> ContextKind)
-> IOEnv (Env TcGblEnv TcLclEnv) Type -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ksig
                  Maybe (LHsKind GhcRn)
Nothing   -> ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (ContextKind -> TcM ContextKind) -> ContextKind -> TcM ContextKind
forall a b. (a -> b) -> a -> b
$ InitialKindStrategy -> NewOrData -> ContextKind
dataDeclDefaultResultKind InitialKindStrategy
strategy (DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn)) -> NewOrData
forall a. DataDefnCons a -> NewOrData
dataDefnConsNewOrData DataDefnCons (LConDecl GhcRn)
DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn))
cons)
        ; return [tc] }

getInitialKind InitialKindStrategy
InitialKindInfer (FamDecl { tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
tcdFam = FamilyDecl GhcRn
decl })
  = do { tc <- Maybe TyCon -> FamilyDecl GhcRn -> TcRn TyCon
get_fam_decl_initial_kind Maybe TyCon
forall a. Maybe a
Nothing FamilyDecl GhcRn
decl
       ; return [tc] }

getInitialKind (InitialKindCheck SAKS_or_CUSK
msig) (FamDecl { tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
tcdFam =
  FamilyDecl { fdLName :: forall pass. FamilyDecl pass -> LIdP pass
fdLName     = LIdP GhcRn -> Name
LocatedN Name -> Name
forall l e. GenLocated l e -> e
unLoc -> Name
name
             , fdTyVars :: forall pass. FamilyDecl pass -> LHsQTyVars pass
fdTyVars    = LHsQTyVars GhcRn
ktvs
             , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = LFamilyResultSig GhcRn -> FamilyResultSig GhcRn
GenLocated EpAnnCO (FamilyResultSig GhcRn) -> FamilyResultSig GhcRn
forall l e. GenLocated l e -> e
unLoc -> FamilyResultSig GhcRn
resultSig
             , fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo      = FamilyInfo GhcRn
info } } )
  = do { let flav :: TyConFlavour TyCon
flav = Maybe TyCon -> FamilyInfo GhcRn -> TyConFlavour TyCon
forall tc pass. Maybe tc -> FamilyInfo pass -> TyConFlavour tc
familyInfoTyConFlavour Maybe TyCon
forall a. Maybe a
Nothing FamilyInfo GhcRn
info
             ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TyFamResKindCtxt Name
name
       ; tc <- InitialKindStrategy
-> Name
-> TyConFlavour TyCon
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader (SAKS_or_CUSK -> InitialKindStrategy
InitialKindCheck SAKS_or_CUSK
msig) Name
name TyConFlavour TyCon
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
               case FamilyResultSig GhcRn -> Maybe (LHsKind GhcRn)
forall (p :: Pass).
FamilyResultSig (GhcPass p) -> Maybe (LHsKind (GhcPass p))
famResultKindSignature FamilyResultSig GhcRn
resultSig of
                 Just LHsKind GhcRn
ksig -> Type -> ContextKind
TheKind (Type -> ContextKind)
-> IOEnv (Env TcGblEnv TcLclEnv) Type -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ksig
                 Maybe (LHsKind GhcRn)
Nothing ->
                   case SAKS_or_CUSK
msig of
                     SAKS_or_CUSK
CUSK -> ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> ContextKind
TheKind Type
liftedTypeKind)
                     SAKS Type
_ -> ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ContextKind
AnyKind
       ; return [tc] }

getInitialKind InitialKindStrategy
strategy
    (SynDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
name
             , tcdTyVars :: forall pass. TyClDecl pass -> LHsQTyVars pass
tcdTyVars = LHsQTyVars GhcRn
ktvs
             , tcdRhs :: forall pass. TyClDecl pass -> LHsType pass
tcdRhs = LHsKind GhcRn
rhs })
  = do { let ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TySynKindCtxt Name
name
       ; tc <- InitialKindStrategy
-> Name
-> TyConFlavour TyCon
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
strategy Name
name TyConFlavour TyCon
forall tc. TyConFlavour tc
TypeSynonymFlavour LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
               case LHsKind GhcRn -> Maybe (LHsKind GhcRn)
forall (p :: Pass).
LHsType (GhcPass p) -> Maybe (LHsType (GhcPass p))
hsTyKindSig LHsKind GhcRn
rhs of
                 Just LHsKind GhcRn
rhs_sig -> Type -> ContextKind
TheKind (Type -> ContextKind)
-> IOEnv (Env TcGblEnv TcLclEnv) Type -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
rhs_sig
                 Maybe (LHsKind GhcRn)
Nothing -> ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ContextKind
AnyKind
       ; return [tc] }

get_fam_decl_initial_kind
  :: Maybe TcTyCon -- ^ Just cls <=> this is an associated family of class cls
  -> FamilyDecl GhcRn
  -> TcM TcTyCon
get_fam_decl_initial_kind :: Maybe TyCon -> FamilyDecl GhcRn -> TcRn TyCon
get_fam_decl_initial_kind Maybe TyCon
mb_parent_tycon
    FamilyDecl { fdLName :: forall pass. FamilyDecl pass -> LIdP pass
fdLName     = L SrcSpanAnnN
_ Name
name
               , fdTyVars :: forall pass. FamilyDecl pass -> LHsQTyVars pass
fdTyVars    = LHsQTyVars GhcRn
ktvs
               , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = L EpAnnCO
_ FamilyResultSig GhcRn
resultSig
               , fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo      = FamilyInfo GhcRn
info }
  = InitialKindStrategy
-> Name
-> TyConFlavour TyCon
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader InitialKindStrategy
InitialKindInfer Name
name TyConFlavour TyCon
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    case FamilyResultSig GhcRn
resultSig of
      KindSig XCKindSig GhcRn
_ LHsKind GhcRn
ki                            -> Type -> ContextKind
TheKind (Type -> ContextKind)
-> IOEnv (Env TcGblEnv TcLclEnv) Type -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ki
      TyVarSig XTyVarSig GhcRn
_ (L SrcSpanAnnA
_ (KindedTyVar XKindedTyVar GhcRn
_ ()
_ LIdP GhcRn
_ LHsKind GhcRn
ki)) -> Type -> ContextKind
TheKind (Type -> ContextKind)
-> IOEnv (Env TcGblEnv TcLclEnv) Type -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ki
      FamilyResultSig GhcRn
_ -- open type families have * return kind by default
        | TyConFlavour TyCon -> Bool
forall tc. TyConFlavour tc -> Bool
tcFlavourIsOpen TyConFlavour TyCon
flav              -> ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> ContextKind
TheKind Type
liftedTypeKind)
               -- closed type families have their return kind inferred
               -- by default
        | Bool
otherwise                         -> ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ContextKind
AnyKind
  where
    flav :: TyConFlavour TyCon
flav = Maybe TyCon -> FamilyInfo GhcRn -> TyConFlavour TyCon
forall tc pass. Maybe tc -> FamilyInfo pass -> TyConFlavour tc
familyInfoTyConFlavour Maybe TyCon
mb_parent_tycon FamilyInfo GhcRn
info
    ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TyFamResKindCtxt Name
name

-- See Note [Standalone kind signatures for associated types]
check_initial_kind_assoc_fam
  :: TcTyCon -- parent class
  -> FamilyDecl GhcRn
  -> TcM TcTyCon
check_initial_kind_assoc_fam :: TyCon -> FamilyDecl GhcRn -> TcRn TyCon
check_initial_kind_assoc_fam TyCon
cls
  FamilyDecl
    { fdLName :: forall pass. FamilyDecl pass -> LIdP pass
fdLName     = LIdP GhcRn -> Name
LocatedN Name -> Name
forall l e. GenLocated l e -> e
unLoc -> Name
name
    , fdTyVars :: forall pass. FamilyDecl pass -> LHsQTyVars pass
fdTyVars    = LHsQTyVars GhcRn
ktvs
    , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = LFamilyResultSig GhcRn -> FamilyResultSig GhcRn
GenLocated EpAnnCO (FamilyResultSig GhcRn) -> FamilyResultSig GhcRn
forall l e. GenLocated l e -> e
unLoc -> FamilyResultSig GhcRn
resultSig
    , fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo      = FamilyInfo GhcRn
info }
  = InitialKindStrategy
-> Name
-> TyConFlavour TyCon
-> LHsQTyVars GhcRn
-> TcM ContextKind
-> TcRn TyCon
kcDeclHeader (SAKS_or_CUSK -> InitialKindStrategy
InitialKindCheck SAKS_or_CUSK
CUSK) Name
name TyConFlavour TyCon
flav LHsQTyVars GhcRn
ktvs (TcM ContextKind -> TcRn TyCon) -> TcM ContextKind -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$
    case FamilyResultSig GhcRn -> Maybe (LHsKind GhcRn)
forall (p :: Pass).
FamilyResultSig (GhcPass p) -> Maybe (LHsKind (GhcPass p))
famResultKindSignature FamilyResultSig GhcRn
resultSig of
      Just LHsKind GhcRn
ksig -> Type -> ContextKind
TheKind (Type -> ContextKind)
-> IOEnv (Env TcGblEnv TcLclEnv) Type -> TcM ContextKind
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UserTypeCtxt -> LHsKind GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcLHsKindSig UserTypeCtxt
ctxt LHsKind GhcRn
ksig
      Maybe (LHsKind GhcRn)
Nothing -> ContextKind -> TcM ContextKind
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> ContextKind
TheKind Type
liftedTypeKind)
  where
    ctxt :: UserTypeCtxt
ctxt = Name -> UserTypeCtxt
TyFamResKindCtxt Name
name
    flav :: TyConFlavour TyCon
flav = Maybe TyCon -> FamilyInfo GhcRn -> TyConFlavour TyCon
forall tc pass. Maybe tc -> FamilyInfo pass -> TyConFlavour tc
familyInfoTyConFlavour (TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
cls) FamilyInfo GhcRn
info

{- Note [Standalone kind signatures for associated types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If associated types had standalone kind signatures, would they wear them

---------------------------+------------------------------
  like this? (OUT)         |   or like this? (IN)
---------------------------+------------------------------
  type T :: Type -> Type   |   class C a where
  class C a where          |     type T :: Type -> Type
    type T a               |     type T a

The (IN) variant is syntactically ambiguous:

  class C a where
    type T :: a   -- standalone kind signature?
    type T :: a   -- declaration header?

The (OUT) variant does not suffer from this issue, but it might not be the
direction in which we want to take Haskell: we seek to unify type families and
functions, and, by extension, associated types with class methods. And yet we
give class methods their signatures inside the class, not outside. Neither do
we have the counterpart of InstanceSigs for StandaloneKindSignatures.

For now, we dodge the question by using CUSKs for associated types instead of
standalone kind signatures. This is a simple addition to the rule we used to
have before standalone kind signatures:

  old rule:  associated type has a CUSK iff its parent class has a CUSK
  new rule:  associated type has a CUSK iff its parent class has a CUSK or a standalone kind signature

-}

-- See Note [Data declaration default result kind]
dataDeclDefaultResultKind :: InitialKindStrategy ->  NewOrData -> ContextKind
dataDeclDefaultResultKind :: InitialKindStrategy -> NewOrData -> ContextKind
dataDeclDefaultResultKind InitialKindStrategy
strategy NewOrData
new_or_data
  | NewOrData
NewType <- NewOrData
new_or_data
  = ContextKind
OpenKind -- See Note [Implementation of UnliftedNewtypes], point <Error Messages>.
  | NewOrData
DataType <- NewOrData
new_or_data
  , InitialKindCheck (SAKS Type
_) <- InitialKindStrategy
strategy
  = ContextKind
OpenKind -- See Note [Implementation of UnliftedDatatypes]
  | Bool
otherwise
  = Type -> ContextKind
TheKind Type
liftedTypeKind

{- Note [Data declaration default result kind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When the user has not written an inline result kind annotation on a data
declaration, we assume it to be 'Type'. That is, the following declarations
D1 and D2 are considered equivalent:

  data D1         where ...
  data D2 :: Type where ...

The consequence of this assumption is that we reject D3 even though we
accept D4:

  data D3 where
    MkD3 :: ... -> D3 param

  data D4 :: Type -> Type where
    MkD4 :: ... -> D4 param

However, there are two twists:

  * For unlifted newtypes, we must relax the assumed result kind to (TYPE r):

      newtype D5 where
        MkD5 :: Int# -> D5

    See Note [Implementation of UnliftedNewtypes], STEP 1 and it's sub-note
    <Error Messages>.

  * For unlifted datatypes, we must relax the assumed result kind to
    (TYPE (BoxedRep l)) in the presence of a SAKS:

      type D6 :: Type -> TYPE (BoxedRep Unlifted)
      data D6 a = MkD6 a

    Otherwise, it would be impossible to declare unlifted data types in H98
    syntax (which doesn't allow specification of a result kind).

-}

------------------------------------------------------------------------
kcLTyClDecl :: LTyClDecl GhcRn -> TcM ()
  -- See Note [Kind checking for type and class decls]
  -- Called only for declarations without a signature (no CUSKs or SAKs here)
kcLTyClDecl :: LTyClDecl GhcRn -> TcRn ()
kcLTyClDecl (L SrcSpanAnnA
loc TyClDecl GhcRn
decl)
  = SrcSpanAnnA -> TcRn () -> TcRn ()
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    do { tycon <- HasDebugCallStack => Name -> TcRn TyCon
Name -> TcRn TyCon
tcLookupTcTyCon IdP GhcRn
Name
tc_name   -- Always a MonoTcTyCon
       ; traceTc "kcTyClDecl {" (ppr tc_name)
       ; addVDQNote tycon $   -- See Note [Inferring visible dependent quantification]
         addErrCtxt (tcMkDeclCtxt decl) $
         kcTyClDecl decl tycon
       ; traceTc "kcTyClDecl done }" (ppr tc_name) }
  where
    tc_name :: IdP GhcRn
tc_name = TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl

kcTyClDecl :: TyClDecl GhcRn -> MonoTcTyCon -> TcM ()
-- This function is used solely for its side effect on kind variables
-- NB kind signatures on the type variables and
--    result kind signature have already been dealt with
--    by inferInitialKind, so we can ignore them here.

-- NB these equations just extend the type environment with carefully constructed
-- TcTyVars rather than create skolemised variables for the bound variables.
-- - inferInitialKinds makes the TcTyCon where the  tyvars are TcTyVars
-- - In this function, those TcTyVars are unified with other kind variables during
--   kind inference (see GHC.Tc.TyCl Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon])

kcTyClDecl :: TyClDecl GhcRn -> TyCon -> TcRn ()
kcTyClDecl (DataDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName    = (L SrcSpanAnnN
_ Name
_name), tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn { dd_ctxt :: forall pass. HsDataDefn pass -> Maybe (LHsContext pass)
dd_ctxt = Maybe (LHsContext GhcRn)
ctxt, dd_cons :: forall pass. HsDataDefn pass -> DataDefnCons (LConDecl pass)
dd_cons = DataDefnCons (LConDecl GhcRn)
cons } }) TyCon
tycon
  = [(Name, Var)] -> TcRn () -> TcRn ()
forall r. [(Name, Var)] -> TcM r -> TcM r
tcExtendNameTyVarEnv (TyCon -> [(Name, Var)]
tcTyConScopedTyVars TyCon
tycon) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
       -- NB: binding these tyvars isn't necessary for GADTs, but it does no
       -- harm.  For GADTs, each data con brings its own tyvars into scope,
       -- and the ones from this bindTyClTyVars are either not mentioned or
       -- (conceivably) shadowed.
    do { String -> SDoc -> TcRn ()
traceTc String
"kcTyClDecl" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tycon SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [Var] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [Var]
tyConTyVars TyCon
tycon) SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Type
tyConResKind TyCon
tycon))
       ; _ <- Maybe (LHsContext GhcRn) -> TcM ThetaType
tcHsContext Maybe (LHsContext GhcRn)
ctxt
       ; kcConDecls (dataDefnConsNewOrData cons) (tyConResKind tycon) cons
       }

kcTyClDecl (SynDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
_name, tcdRhs :: forall pass. TyClDecl pass -> LHsType pass
tcdRhs = LHsKind GhcRn
rhs }) TyCon
tycon
  = [(Name, Var)] -> TcRn () -> TcRn ()
forall r. [(Name, Var)] -> TcM r -> TcM r
tcExtendNameTyVarEnv (TyCon -> [(Name, Var)]
tcTyConScopedTyVars TyCon
tycon) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    let res_kind :: Type
res_kind = TyCon -> Type
tyConResKind TyCon
tycon
    in IOEnv (Env TcGblEnv TcLclEnv) Type -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult (IOEnv (Env TcGblEnv TcLclEnv) Type -> TcRn ())
-> IOEnv (Env TcGblEnv TcLclEnv) Type -> TcRn ()
forall a b. (a -> b) -> a -> b
$ LHsKind GhcRn -> ContextKind -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcCheckLHsType LHsKind GhcRn
rhs (Type -> ContextKind
TheKind Type
res_kind)
        -- NB: check against the result kind that we allocated
        -- in inferInitialKinds.

kcTyClDecl (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
_name
                      , tcdCtxt :: forall pass. TyClDecl pass -> Maybe (LHsContext pass)
tcdCtxt = Maybe (LHsContext GhcRn)
ctxt, tcdSigs :: forall pass. TyClDecl pass -> [LSig pass]
tcdSigs = [LSig GhcRn]
sigs }) TyCon
tycon
  = [(Name, Var)] -> TcRn () -> TcRn ()
forall r. [(Name, Var)] -> TcM r -> TcM r
tcExtendNameTyVarEnv (TyCon -> [(Name, Var)]
tcTyConScopedTyVars TyCon
tycon) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    do  { _ <- Maybe (LHsContext GhcRn) -> TcM ThetaType
tcHsContext Maybe (LHsContext GhcRn)
ctxt
        ; mapM_ (wrapLocMA_ kc_sig) sigs }
  where
    kc_sig :: Sig GhcRn -> TcRn ()
kc_sig (ClassOpSig XClassOpSig GhcRn
_ Bool
_ [LIdP GhcRn]
nms LHsSigType GhcRn
op_ty) = [LocatedN Name] -> LHsSigType GhcRn -> TcRn ()
kcClassSigType [LIdP GhcRn]
[LocatedN Name]
nms LHsSigType GhcRn
op_ty
    kc_sig Sig GhcRn
_                          = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

kcTyClDecl (FamDecl XFamDecl GhcRn
_ (FamilyDecl { fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo   = FamilyInfo GhcRn
fd_info })) TyCon
fam_tc
-- closed type families look at their equations, but other families don't
-- do anything here
  = case FamilyInfo GhcRn
fd_info of
      ClosedTypeFamily (Just [LTyFamInstEqn GhcRn]
eqns) -> (GenLocated
   SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))
 -> TcRn ())
-> [GenLocated
      SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))]
-> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (TyCon -> LTyFamInstEqn GhcRn -> TcRn ()
kcTyFamInstEqn TyCon
fam_tc) [LTyFamInstEqn GhcRn]
[GenLocated
   SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))]
eqns
      FamilyInfo GhcRn
_ -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

-------------------

-- Kind-check the types of the arguments to a data constructor.
-- This includes doing kind unification if the type is a newtype.
-- See Note [Implementation of UnliftedNewtypes] for why we need
-- the first two arguments.
kcConArgTys :: NewOrData -> TcKind -> [HsScaled GhcRn (LHsType GhcRn)] -> TcM ()
kcConArgTys :: NewOrData -> Type -> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
kcConArgTys NewOrData
new_or_data Type
res_kind [HsScaled GhcRn (LHsKind GhcRn)]
arg_tys = do
  { let exp_kind :: ContextKind
exp_kind = NewOrData -> Type -> ContextKind
getArgExpKind NewOrData
new_or_data Type
res_kind
  ; [HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> (HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
    -> IOEnv (Env TcGblEnv TcLclEnv) Type)
-> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
t a -> (a -> m b) -> m ()
forM_ [HsScaled GhcRn (LHsKind GhcRn)]
[HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
arg_tys (\(HsScaled HsArrow GhcRn
mult GenLocated SrcSpanAnnA (HsType GhcRn)
ty) -> do _ <- LHsKind GhcRn -> ContextKind -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcCheckLHsType (LHsKind GhcRn -> LHsKind GhcRn
forall (p :: Pass). LHsType (GhcPass p) -> LHsType (GhcPass p)
getBangType LHsKind GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
ty) ContextKind
exp_kind
                                             tcMult mult)
    -- See Note [Implementation of UnliftedNewtypes], STEP 2
  }

-- Kind-check the types of arguments to a Haskell98 data constructor.
kcConH98Args :: NewOrData -> TcKind -> HsConDeclH98Details GhcRn -> TcM ()
kcConH98Args :: NewOrData -> Type -> HsConDeclH98Details GhcRn -> TcRn ()
kcConH98Args NewOrData
new_or_data Type
res_kind HsConDeclH98Details GhcRn
con_args = case HsConDeclH98Details GhcRn
con_args of
  PrefixCon [Void]
_ [HsScaled GhcRn (LHsKind GhcRn)]
tys   -> NewOrData -> Type -> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
kcConArgTys NewOrData
new_or_data Type
res_kind [HsScaled GhcRn (LHsKind GhcRn)]
tys
  InfixCon HsScaled GhcRn (LHsKind GhcRn)
ty1 HsScaled GhcRn (LHsKind GhcRn)
ty2  -> NewOrData -> Type -> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
kcConArgTys NewOrData
new_or_data Type
res_kind [HsScaled GhcRn (LHsKind GhcRn)
ty1, HsScaled GhcRn (LHsKind GhcRn)
ty2]
  RecCon (L SrcSpanAnnL
_ [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
flds) -> NewOrData -> Type -> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
kcConArgTys NewOrData
new_or_data Type
res_kind ([HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ())
-> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                       (GenLocated SrcSpanAnnA (ConDeclField GhcRn)
 -> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))
-> [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
-> [HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a b. (a -> b) -> [a] -> [b]
map (GenLocated SrcSpanAnnA (HsType GhcRn)
-> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
forall (p :: Pass) a. IsPass p => a -> HsScaled (GhcPass p) a
hsLinear (GenLocated SrcSpanAnnA (HsType GhcRn)
 -> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))
-> (GenLocated SrcSpanAnnA (ConDeclField GhcRn)
    -> GenLocated SrcSpanAnnA (HsType GhcRn))
-> GenLocated SrcSpanAnnA (ConDeclField GhcRn)
-> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ConDeclField GhcRn -> LHsKind GhcRn
ConDeclField GhcRn -> GenLocated SrcSpanAnnA (HsType GhcRn)
forall pass. ConDeclField pass -> LBangType pass
cd_fld_type (ConDeclField GhcRn -> GenLocated SrcSpanAnnA (HsType GhcRn))
-> (GenLocated SrcSpanAnnA (ConDeclField GhcRn)
    -> ConDeclField GhcRn)
-> GenLocated SrcSpanAnnA (ConDeclField GhcRn)
-> GenLocated SrcSpanAnnA (HsType GhcRn)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (ConDeclField GhcRn) -> ConDeclField GhcRn
forall l e. GenLocated l e -> e
unLoc) [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
flds

-- Kind-check the types of arguments to a GADT data constructor.
kcConGADTArgs :: NewOrData -> TcKind -> HsConDeclGADTDetails GhcRn -> TcM ()
kcConGADTArgs :: NewOrData -> Type -> HsConDeclGADTDetails GhcRn -> TcRn ()
kcConGADTArgs NewOrData
new_or_data Type
res_kind HsConDeclGADTDetails GhcRn
con_args = case HsConDeclGADTDetails GhcRn
con_args of
  PrefixConGADT XPrefixConGADT GhcRn
_ [HsScaled GhcRn (LHsKind GhcRn)]
tys     -> NewOrData -> Type -> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
kcConArgTys NewOrData
new_or_data Type
res_kind [HsScaled GhcRn (LHsKind GhcRn)]
tys
  RecConGADT XRecConGADT GhcRn
_ (L SrcSpanAnnL
_ [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
flds) -> NewOrData -> Type -> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
kcConArgTys NewOrData
new_or_data Type
res_kind ([HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ())
-> [HsScaled GhcRn (LHsKind GhcRn)] -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                             (GenLocated SrcSpanAnnA (ConDeclField GhcRn)
 -> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))
-> [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
-> [HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
forall a b. (a -> b) -> [a] -> [b]
map (GenLocated SrcSpanAnnA (HsType GhcRn)
-> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
forall (p :: Pass) a. IsPass p => a -> HsScaled (GhcPass p) a
hsLinear (GenLocated SrcSpanAnnA (HsType GhcRn)
 -> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))
-> (GenLocated SrcSpanAnnA (ConDeclField GhcRn)
    -> GenLocated SrcSpanAnnA (HsType GhcRn))
-> GenLocated SrcSpanAnnA (ConDeclField GhcRn)
-> HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ConDeclField GhcRn -> LHsKind GhcRn
ConDeclField GhcRn -> GenLocated SrcSpanAnnA (HsType GhcRn)
forall pass. ConDeclField pass -> LBangType pass
cd_fld_type (ConDeclField GhcRn -> GenLocated SrcSpanAnnA (HsType GhcRn))
-> (GenLocated SrcSpanAnnA (ConDeclField GhcRn)
    -> ConDeclField GhcRn)
-> GenLocated SrcSpanAnnA (ConDeclField GhcRn)
-> GenLocated SrcSpanAnnA (HsType GhcRn)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (ConDeclField GhcRn) -> ConDeclField GhcRn
forall l e. GenLocated l e -> e
unLoc) [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
flds

kcConDecls :: Foldable f
           => NewOrData
           -> TcKind             -- The result kind signature
                               --   Used only in H98 case
           -> f (LConDecl GhcRn) -- The data constructors
           -> TcM ()
-- See Note [kcConDecls: kind-checking data type decls]
kcConDecls :: forall (f :: * -> *).
Foldable f =>
NewOrData -> Type -> f (LConDecl GhcRn) -> TcRn ()
kcConDecls NewOrData
new_or_data Type
tc_res_kind = (GenLocated SrcSpanAnnA (ConDecl GhcRn) -> TcRn ())
-> f (GenLocated SrcSpanAnnA (ConDecl GhcRn)) -> TcRn ()
forall (t :: * -> *) (f :: * -> *) a b.
(Foldable t, Applicative f) =>
(a -> f b) -> t a -> f ()
traverse_ ((ConDecl GhcRn -> TcRn ())
-> GenLocated SrcSpanAnnA (ConDecl GhcRn) -> TcRn ()
forall a. (a -> TcRn ()) -> LocatedA a -> TcRn ()
wrapLocMA_ (NewOrData -> Type -> ConDecl GhcRn -> TcRn ()
kcConDecl NewOrData
new_or_data Type
tc_res_kind))

-- Kind check a data constructor. In additional to the data constructor,
-- we also need to know about whether or not its corresponding type was
-- declared with data or newtype, and we need to know the result kind of
-- this type. See Note [Implementation of UnliftedNewtypes] for why
-- we need the first two arguments.
kcConDecl :: NewOrData
          -> TcKind  -- Result kind of the type constructor
                   -- Usually Type but can be TYPE UnliftedRep
                   -- or even TYPE r, in the case of unlifted newtype
                   -- Used only in H98 case
          -> ConDecl GhcRn
          -> TcM ()
kcConDecl :: NewOrData -> Type -> ConDecl GhcRn -> TcRn ()
kcConDecl NewOrData
new_or_data Type
tc_res_kind (ConDeclH98
  { con_name :: forall pass. ConDecl pass -> LIdP pass
con_name = LIdP GhcRn
name, con_ex_tvs :: forall pass. ConDecl pass -> [LHsTyVarBndr Specificity pass]
con_ex_tvs = [LHsTyVarBndr Specificity GhcRn]
ex_tvs
  , con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (LHsContext GhcRn)
ex_ctxt, con_args :: forall pass. ConDecl pass -> HsConDeclH98Details pass
con_args = HsConDeclH98Details GhcRn
args })
  = SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (NonEmpty (LocatedN Name) -> SDoc
dataConCtxt (LocatedN Name -> NonEmpty (LocatedN Name)
forall a. a -> NonEmpty a
NE.singleton LIdP GhcRn
LocatedN Name
name)) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    TcM ([VarBndr Var Specificity], ()) -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult                   (TcM ([VarBndr Var Specificity], ()) -> TcRn ())
-> TcM ([VarBndr Var Specificity], ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    [LHsTyVarBndr Specificity GhcRn]
-> TcRn () -> TcM ([VarBndr Var Specificity], ())
forall flag a.
OutputableBndrFlag flag 'Renamed =>
[LHsTyVarBndr flag GhcRn] -> TcM a -> TcM ([VarBndr Var flag], a)
bindExplicitTKBndrs_Tv [LHsTyVarBndr Specificity GhcRn]
ex_tvs (TcRn () -> TcM ([VarBndr Var Specificity], ()))
-> TcRn () -> TcM ([VarBndr Var Specificity], ())
forall a b. (a -> b) -> a -> b
$
    do { _ <- Maybe (LHsContext GhcRn) -> TcM ThetaType
tcHsContext Maybe (LHsContext GhcRn)
ex_ctxt
       ; kcConH98Args new_or_data tc_res_kind args
         -- We don't need to check the telescope here,
         -- because that's done in tcConDecl
       }

kcConDecl NewOrData
new_or_data
          Type
_tc_res_kind   -- Not used in GADT case (and doesn't make sense)
          (ConDeclGADT
    { con_names :: forall pass. ConDecl pass -> NonEmpty (LIdP pass)
con_names = NonEmpty (LIdP GhcRn)
names, con_bndrs :: forall pass. ConDecl pass -> XRec pass (HsOuterSigTyVarBndrs pass)
con_bndrs = L SrcSpanAnnA
_ HsOuterSigTyVarBndrs GhcRn
outer_bndrs, con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (LHsContext GhcRn)
cxt
    , con_g_args :: forall pass. ConDecl pass -> HsConDeclGADTDetails pass
con_g_args = HsConDeclGADTDetails GhcRn
args, con_res_ty :: forall pass. ConDecl pass -> LHsType pass
con_res_ty = LHsKind GhcRn
res_ty })
  = -- See Note [kcConDecls: kind-checking data type decls]
    SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (NonEmpty (LocatedN Name) -> SDoc
dataConCtxt NonEmpty (LIdP GhcRn)
NonEmpty (LocatedN Name)
names) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    TcM (HsOuterSigTyVarBndrs GhcTc, ()) -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult                      (TcM (HsOuterSigTyVarBndrs GhcTc, ()) -> TcRn ())
-> TcM (HsOuterSigTyVarBndrs GhcTc, ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    -- Not sure this is right, should just extend rather than skolemise but no test
    HsOuterSigTyVarBndrs GhcRn
-> TcRn () -> TcM (HsOuterSigTyVarBndrs GhcTc, ())
forall a.
HsOuterSigTyVarBndrs GhcRn
-> TcM a -> TcM (HsOuterSigTyVarBndrs GhcTc, a)
bindOuterSigTKBndrs_Tv HsOuterSigTyVarBndrs GhcRn
outer_bndrs (TcRn () -> TcM (HsOuterSigTyVarBndrs GhcTc, ()))
-> TcRn () -> TcM (HsOuterSigTyVarBndrs GhcTc, ())
forall a b. (a -> b) -> a -> b
$
        -- Why "_Tv"?  See Note [Using TyVarTvs for kind-checking GADTs]
    do { _ <- Maybe (LHsContext GhcRn) -> TcM ThetaType
tcHsContext Maybe (LHsContext GhcRn)
cxt
       ; traceTc "kcConDecl:GADT {" (ppr names $$ ppr res_ty)
       ; con_res_kind <- newOpenTypeKind
       ; _ <- tcCheckLHsType res_ty (TheKind con_res_kind)
       ; kcConGADTArgs new_or_data con_res_kind args
       ; traceTc "kcConDecl:GADT }" (ppr names $$ ppr con_res_kind)
       ; return () }

{- Note [kcConDecls: kind-checking data type decls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kcConDecls is used when we are inferring the kind of the type
constructor in a data type declaration.  E.g.
    data T f a = MkT (f a)
we want to infer the kind of 'f' and 'a'. The basic plan is described
in Note [Inferring kinds for type declarations]; here we are doing Step 2.

In the GADT case we may have this:
   data T f a where
      MkT :: forall g b. g b -> T g b

Notice that the variables f,a, and g,b are quite distinct.
Nevertheless, the type signature for MkT must still influence the kind
T which is (remember Step 1) something like
  T :: kappa1 -> kappa2 -> Type
Otherwise we'd infer the bogus kind
  T :: forall k1 k2. k1 -> k2 -> Type.

The type signature for MkT influences the kind of T simply by
kind-checking the result type (T g b), which will force 'f' and 'g' to
have the same kinds. This is the call to
    tcCheckLHsType res_ty (TheKind con_res_kind)
Because this is the result type of an arrow, we know the kind must be
of form (TYPE rr), and we get better error messages if we enforce that
here (e.g. test gadt10).

For unlifted newtypes only, we must ensure that the argument kind
and result kind are the same:
* In the H98 case, we need the result kind of the TyCon, to unify with
  the argument kind.

* In GADT syntax, this unification happens via the result kind passed
  to kcConGADTArgs. The tycon's result kind is not used at all in the
  GADT case.

Note [Using TyVarTvs for kind-checking GADTs]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider

  data Proxy a where
    MkProxy1 :: forall k (b :: k). Proxy b
    MkProxy2 :: forall j (c :: j). Proxy c

It seems reasonable that this should be accepted. But something very strange
is going on here: when we're kind-checking this declaration, we need to unify
the kind of `a` with k and j -- even though k and j's scopes are local to the type of
MkProxy{1,2}.

In effect, we are simply gathering constraints on the shape of Proxy's
kind, with no skolemisation or implication constraints involved at all.

The best approach we've come up with is to use TyVarTvs during the
kind-checking pass, rather than ordinary skolems. This is why we use
the "_Tv" variant, bindOuterSigTKBndrs_Tv.

Our only goal is to gather constraints on the kind of the type constructor;
we do not certify that the data declaration is well-kinded. For example:

  data SameKind :: k -> k -> Type
  data Bad a where
    MkBad :: forall k1 k2 (a :: k1) (b :: k2). Bad (SameKind a b)

which would be accepted by kcConDecl because k1 and k2 are
TyVarTvs. It is correctly rejected in the second pass, tcConDecl.
(Test case: polykinds/TyVarTvKinds3)

One drawback of this approach is sometimes it will accept a definition that
a (hypothetical) declarative specification would likely reject. As a general
rule, we don't want to allow polymorphic recursion without a CUSK. Indeed,
the whole point of CUSKs is to allow polymorphic recursion. Yet, the TyVarTvs
approach allows a limited form of polymorphic recursion *without* a CUSK.

To wit:
  data T a = forall k (b :: k). MkT (T b) Int
  (test case: dependent/should_compile/T14066a)

Note that this is polymorphically recursive, with the recursive occurrence
of T used at a kind other than a's kind. The approach outlined here accepts
this definition, because this kind is still a kind variable (and so the
TyVarTvs unify). Stepping back, I (Richard) have a hard time envisioning a
way to describe exactly what declarations will be accepted and which will
be rejected (without a CUSK). However, the accepted definitions are indeed
well-kinded and any rejected definitions would be accepted with a CUSK,
and so this wrinkle need not cause anyone to lose sleep.

Note [Recursion and promoting data constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We don't want to allow promotion in a strongly connected component
when kind checking.

Consider:
  data T f = K (f (K Any))

When kind checking the `data T' declaration the local env contains the
mappings:
  T -> ATcTyCon <some initial kind>
  K -> APromotionErr

APromotionErr is only used for DataCons, and only used during type checking
in tcTyClGroup.

The same restriction applies constructors in to "type data" declarations.
See Note [Type data declarations] in GHC.Rename.Module.


************************************************************************
*                                                                      *
\subsection{Type checking}
*                                                                      *
************************************************************************

Note [Type checking recursive type and class declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
At this point we have completed *kind-checking* of a mutually
recursive group of type/class decls (done in kcTyClGroup). However,
we discarded the kind-checked types (eg RHSs of data type decls);
note that kcTyClDecl returns ().  There are two reasons:

  * It's convenient, because we don't have to rebuild a
    kinded HsDecl (a fairly elaborate type)

  * It's necessary, because after kind-generalisation, the
    TyCons/Classes may now be kind-polymorphic, and hence need
    to be given kind arguments.

Example:
       data T f a = MkT (f a) (T f a)
During kind-checking, we give T the kind T :: k1 -> k2 -> *
and figure out constraints on k1, k2 etc. Then we generalise
to get   T :: forall k. (k->*) -> k -> *
So now the (T f a) in the RHS must be elaborated to (T k f a).

However, during tcTyClDecl of T (above) we will be in a recursive
"knot". So we aren't allowed to look at the TyCon T itself; we are only
allowed to put it (lazily) in the returned structures.  But when
kind-checking the RHS of T's decl, we *do* need to know T's kind (so
that we can correctly elaborate (T k f a).  How can we get T's kind
without looking at T?  Delicate answer: during tcTyClDecl, we extend

  *Global* env with T -> ATyCon (the (not yet built) final TyCon for T)
  *Local*  env with T -> ATcTyCon (TcTyCon with the polymorphic kind of T)

Then:

  * During GHC.Tc.Gen.HsType.tcTyVar we look in the *local* env, to get the
    fully-known, not knot-tied TcTyCon for T.

  * Then, in GHC.Tc.Zonk.Type.zonkTcTypeToType (and zonkTcTyCon in particular)
    we look in the *global* env to get the TyCon.

This fancy footwork (with two bindings for T) is only necessary for the
TyCons or Classes of this recursive group.  Earlier, finished groups,
live in the global env only.

See also Note [Kind checking recursive type and class declarations]

Note [Kind checking recursive type and class declarations]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Before we can type-check the decls, we must kind check them. This
is done by establishing an "initial kind", which is a rather uninformed
guess at a tycon's kind (by counting arguments, mainly) and then
using this initial kind for recursive occurrences.

The initial kind is stored in exactly the same way during
kind-checking as it is during type-checking (Note [Type checking
recursive type and class declarations]): in the *local* environment,
with ATcTyCon. But we still must store *something* in the *global*
environment. Even though we discard the result of kind-checking, we
sometimes need to produce error messages. These error messages will
want to refer to the tycons being checked, except that they don't
exist yet, and it would be Terribly Annoying to get the error messages
to refer back to HsSyn. So we create a TcTyCon and put it in the
global env. This tycon can print out its name and knows its kind, but
any other action taken on it will panic. Note that TcTyCons are *not*
knot-tied, unlike the rather valid but knot-tied ones that occur
during type-checking.

Note [Declarations for wired-in things]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For wired-in things we simply ignore the declaration
and take the wired-in information.  That avoids complications.
e.g. the need to make the data constructor worker name for
     a constraint tuple match the wired-in one

Note [Datatype return kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There are several poorly lit corners around datatype/newtype return kinds.
This Note explains these.  We cover data/newtype families and instances
in Note [Data family/instance return kinds].

data    T a :: <kind> where ...   -- See Point DT4
newtype T a :: <kind> where ...   -- See Point DT5

DT1 Where this applies: Only GADT syntax for data/newtype/instance declarations
    can have declared return kinds. This Note does not apply to Haskell98
    syntax.

DT2 Where these kinds come from: The return kind is part of the TyCon kind, gotten either
     by checkInitialKind (standalone kind signature / CUSK) or
     inferInitialKind. It is extracted by bindTyClTyVars in tcTyClDecl1. It is
     then passed to tcDataDefn.

DT3 Eta-expansion: Any forall-bound variables and function arguments in a result kind
    become parameters to the type. That is, when we say

     data T a :: Type -> Type where ...

    we really mean for T to have two parameters. The second parameter
    is produced by processing the return kind in etaExpandAlgTyCon,
    called in tcDataDefn.

    See also Note [splitTyConKind] in GHC.Tc.Gen.HsType.

DT4 Datatype return kind restriction: A data type return kind must end
    in a type that, after type-synonym expansion, yields `TYPE LiftedRep`. By
    "end in", we mean we strip any foralls and function arguments off before
    checking.

    Examples:
      data T1 :: Type                          -- good
      data T2 :: Bool -> Type                  -- good
      data T3 :: Bool -> forall k. Type        -- strange, but still accepted
      data T4 :: forall k. k -> Type           -- good
      data T5 :: Bool                          -- bad
      data T6 :: Type -> Bool                  -- bad

    Exactly the same applies to data instance (but not data family)
    declarations.  Examples
      data instance D1 :: Type                 -- good
      data instance D2 :: Bool -> Type         -- good

    We can "look through" type synonyms
      type Star = Type
      data T7 :: Bool -> Star                  -- good (synonym expansion ok)
      type Arrow = (->)
      data T8 :: Arrow Bool Type               -- good (ditto)

    But we specifically do *not* do type family reduction here.
      type family ARROW where
        ARROW = (->)
      data T9 :: ARROW Bool Type               -- bad

      type family F a where
        F Int  = Bool
        F Bool = Type
      data T10 :: Bool -> F Bool               -- bad

    The /principle/ here is that in the TyCon for a data type or data instance,
    we must be able to lay out all the type-variable binders, one by one, until
    we reach (TYPE xx).  There is no place for a cast here.  We could add one,
    but let's not!

    This check is done in checkDataKindSig. For data declarations, this
    call is in tcDataDefn; for data instances, this call is in tcDataFamInstDecl.

DT5 Newtype return kind restriction.
    If -XUnliftedNewtypes is not on, then newtypes are treated just
    like datatypes --- see (4) above.

    If -XUnliftedNewtypes is on, then a newtype return kind must end in
    TYPE xyz, for some xyz (after type synonym expansion). The "xyz"
    may include type families, but the TYPE part must be visible
    /without/ expanding type families (only synonyms).

    This kind is unified with the kind of the representation type (the
    type of the one argument to the one constructor). See also steps
    (2) and (3) of Note [Implementation of UnliftedNewtypes].

    The checks are done in the same places as for datatypes.
    Examples (assume -XUnliftedNewtypes):

      newtype N1 :: Type                       -- good
      newtype N2 :: Bool -> Type               -- good
      newtype N3 :: forall r. Bool -> TYPE r   -- good

      type family F (t :: Type) :: RuntimeRep
      newtype N4 :: forall t -> TYPE (F t)     -- good

      type family STAR where
        STAR = Type
      newtype N5 :: Bool -> STAR               -- bad

Note [Data family/instance return kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Within this note, understand "instance" to mean data or newtype
instance, and understand "family" to mean data family. No type
families or classes here. Some examples:

data family T a :: <kind>          -- See Point DF56

data    instance T [a] :: <kind> where ...   -- See Point DF2
newtype instance T [a] :: <kind> where ...   -- See Point DF2

Here is the Plan for Data Families:

DF0 Where these kinds come from:

    Families: The return kind is either written in a standalone signature
     or extracted from a family declaration in getInitialKind.
     If a family declaration is missing a result kind, it is assumed to be
     Type. This assumption is in getInitialKind for CUSKs or
     get_fam_decl_initial_kind for non-signature & non-CUSK cases.

   Instances: The data family already has a known kind. The return kind
     of an instance is then calculated by applying the data family tycon
     to the patterns provided, as computed by the typeKind lhs_ty in the
     end of tcDataFamInstHeader. In the case of an instance written in GADT
     syntax, there are potentially *two* return kinds: the one computed from
     applying the data family tycon to the patterns, and the one given by
     the user. This second kind is checked by the tc_kind_sig function within
     tcDataFamInstHeader. See also DF3, below.

DF1 In a data/newtype instance, we treat the kind of the /data family/,
    once instantiated, as the "master kind" for the representation
    TyCon.  For example:
        data family T1 :: Type -> Type -> Type
        data instance T1 Int :: F Bool -> Type where ...
    The "master kind" for the representation TyCon R:T1Int comes
    from T1, not from the signature on the data instance.  It is as
    if we declared
        data R:T1Int :: Type -> Type where ...
     See Note [Liberalising data family return kinds] for an alternative
     plan.  But this current plan is simple, and ensures that all instances
     are simple instantiations of the master, without strange casts.

     An example with non-trivial instantiation:
        data family T2 :: forall k. Type -> k
        data instance T2 :: Type -> Type -> Type where ...
     Here 'k' gets instantiated with (Type -> Type), driven by
     the signature on the 'data instance'. (See also DT3 of
     Note [Datatype return kinds] about eta-expansion, which applies here,
     too; see tcDataFamInstDecl's call of etaExpandAlgTyCon.)

     A newtype example:

       data Color = Red | Blue
       type family Interpret (x :: Color) :: RuntimeRep where
         Interpret 'Red = 'IntRep
         Interpret 'Blue = 'WordRep
       data family Foo (x :: Color) :: TYPE (Interpret x)
       newtype instance Foo 'Red :: TYPE IntRep where
         FooRedC :: Int# -> Foo 'Red

    Here we get that Foo 'Red :: TYPE (Interpret Red), and our
    representation newtype looks like
         newtype R:FooRed :: TYPE (Interpret Red) where
            FooRedC :: Int# -> R:FooRed
    Remember: the master kind comes from the /family/ tycon.

DF2 /After/ this instantiation, the return kind of the master kind
    must obey the usual rules for data/newtype return kinds (DT4, DT5)
    of Note [Datatype return kinds].  Examples:
        data family T3 k :: k
        data instance T3 Type where ...          -- OK
        data instance T3 (Type->Type) where ...  -- OK
        data instance T3 (F Int) where ...       -- Not OK

DF3 Any kind signatures on the data/newtype instance are checked for
    equality with the master kind (and hence may guide instantiation)
    but are otherwise ignored. So in the T1 example above, we check
    that (F Int ~ Type) by unification; but otherwise ignore the
    user-supplied signature from the /family/ not the /instance/.

    We must be sure to instantiate any trailing invisible binders
    before doing this unification.  See the call to tcInstInvisibleBinders
    in tcDataFamInstHeader. For example:
       data family D :: forall k. k
       data instance D :: Type               -- forall k. k   <:  Type
       data instance D :: Type -> Type       -- forall k. k   <:  Type -> Type
         -- NB: these do not overlap
    we must instantiate D before unifying with the signature in the
    data instance declaration

DF4 We also (redundantly) check that any user-specified return kind
    signature in the data instance also obeys DT4/DT5.  For example we
    reject
        data family T1 :: Type -> Type -> Type
        data instance T1 Int :: Type -> F Int
    even if (F Int ~ Type).  We could omit this check, because we
    use the master kind; but it seems more uniform to check it, again
    with checkDataKindSig.

DF5 Data /family/ return kind restrictions. Consider
       data family D8 a :: F a
    where F is a type family.  No data/newtype instance can instantiate
    this so that it obeys the rules of DT4 or DT5.  So GHC proactively
    rejects the data /family/ declaration if it can never satisfy (DT4)/(DT5).
    Remember that a data family supports both data and newtype instances.

    More precisely, the return kind of a data family must be either
        * TYPE xyz (for some type xyz) or
        * a kind variable
    Only in these cases can a data/newtype instance possibly satisfy (DT4)/(DT5).
    This is checked by the call to checkDataKindSig in tcFamDecl1.  Examples:

      data family D1 :: Type              -- good
      data family D2 :: Bool -> Type      -- good
      data family D3 k :: k               -- good
      data family D4 :: forall k -> k     -- good
      data family D5 :: forall k. k -> k  -- good
      data family D6 :: forall r. TYPE r  -- good
      data family D7 :: Bool -> STAR      -- bad (see STAR from point 5)

DF6 Two return kinds for instances: If an instance has two return kinds,
    one from the family declaration and one from the instance declaration
    (see point DF3 above), they are unified. More accurately, we make sure
    that the kind of the applied data family is a subkind of the user-written
    kind. GHC.Tc.Gen.HsType.checkExpectedKind normally does this check for types, but
    that's overkill for our needs here. Instead, we just instantiate any
    invisible binders in the (instantiated) kind of the data family
    (called lhs_kind in tcDataFamInstHeader) with tcInstInvisibleTyBinders
    and then unify the resulting kind with the kind written by the user.
    This unification naturally produces a coercion, which we can drop, as
    the kind annotation on the instance is redundant (except perhaps for
    effects of unification).

    This all is Wrinkle (3) in Note [Implementation of UnliftedNewtypes].

Note [Liberalising data family return kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Could we allow this?
   type family F a where { F Int = Type }
   data family T a :: F a
   data instance T Int where
      MkT :: T Int

In the 'data instance', T Int :: F Int, and F Int = Type, so all seems
well.  But there are lots of complications:

* The representation constructor R:TInt presumably has kind Type.
  So the axiom connecting the two would have to look like
       axTInt :: T Int ~ R:TInt |> sym axFInt
  and that doesn't match expectation in DataFamInstTyCon
  in AlgTyConFlav

* The wrapper can't have type
     $WMkT :: Int -> T Int
  because T Int has the wrong kind.  It would have to be
     $WMkT :: Int -> (T Int) |> axFInt

* The code for $WMkT would also be more complicated, needing
  two coherence coercions. Try it!

* Code for pattern matching would be complicated in an
  exactly dual way.

So yes, we could allow this, but we currently do not. That's
why we have DF2 in Note [Data family/instance return kinds].

Note [Implementation of UnliftedNewtypes]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Expected behavior of UnliftedNewtypes:

* Proposal: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0013-unlifted-newtypes.rst
* Discussion: https://github.com/ghc-proposals/ghc-proposals/pull/98

What follows is a high-level overview of the implementation of the
proposal.

STEP 1: Getting the initial kind, as done by inferInitialKind. We have
two sub-cases:

* With a SAK/CUSK: no change in kind-checking; the tycon is given the kind
  the user writes, whatever it may be.

* Without a SAK/CUSK: If there is no kind signature, the tycon is given
  a kind `TYPE r`, for a fresh unification variable `r`. We do this even
  when -XUnliftedNewtypes is not on; see <Error Messages>, below.

STEP 2: Kind-checking, as done by kcTyClDecl. This step is skipped for CUSKs.
The key function here is kcConDecl, which looks at an individual constructor
declaration. When we are processing a newtype (but whether or not -XUnliftedNewtypes
is enabled; see <Error Messages>, below), we generate a correct ContextKind
for the checking argument types: see getArgExpKind.

Examples of newtypes affected by STEP 2, assuming -XUnliftedNewtypes is
enabled (we use r0 to denote a unification variable):

newtype Foo rep = MkFoo (forall (a :: TYPE rep). a)
+ kcConDecl unifies (TYPE r0) with (TYPE rep), where (TYPE r0)
  is the kind that inferInitialKind invented for (Foo rep).

data Color = Red | Blue
type family Interpret (x :: Color) :: RuntimeRep where
  Interpret 'Red = 'IntRep
  Interpret 'Blue = 'WordRep
data family Foo (x :: Color) :: TYPE (Interpret x)
newtype instance Foo 'Red = FooRedC Int#
+ kcConDecl unifies TYPE (Interpret 'Red) with TYPE 'IntRep

Note that, in the GADT case, we might have a kind signature with arrows
(newtype XYZ a b :: Type -> Type where ...). We want only the final
component of the kind for checking in kcConDecl, so we call etaExpanAlgTyCon
in kcTyClDecl.

STEP 3: Type-checking (desugaring), as done by tcTyClDecl. The key function
here is tcConDecl. Once again, we must use getArgExpKind to ensure that the
representation type's kind matches that of the newtype, for two reasons:

  A. It is possible that a GADT has a CUSK. (Note that this is *not*
     possible for H98 types.) Recall that CUSK types don't go through
     kcTyClDecl, so we might not have done this kind check.
  B. We need to produce the coercion to put on the argument type
     if the kinds are different (for both H98 and GADT).

Example of (B):

type family F a where
  F Int = LiftedRep

newtype N :: TYPE (F Int) where
  MkN :: Int -> N

We really need to have the argument to MkN be (Int |> TYPE (sym axF)), where
axF :: F Int ~ LiftedRep. That way, the argument kind is the same as the
newtype kind, which is the principal correctness condition for newtypes.

Wrinkle: Consider (#17021, typecheck/should_fail/T17021)

    type family Id (x :: a) :: a where
      Id x = x

    newtype T :: TYPE (Id LiftedRep) where
      MkT :: Int -> T

  In the type of MkT, we must end with (Int |> TYPE (sym axId)) -> T,
  never Int -> (T |> TYPE axId); otherwise, the result type of the
  constructor wouldn't match the datatype. However, type-checking the
  HsType T might reasonably result in (T |> hole). We thus must ensure
  that this cast is dropped, forcing the type-checker to add one to
  the Int instead.

  Why is it always safe to drop the cast? This result type is type-checked by
  tcHsOpenType, so its kind definitely looks like TYPE r, for some r. It is
  important that even after dropping the cast, the type's kind has the form
  TYPE r. This is guaranteed by restrictions on the kinds of datatypes.
  For example, a declaration like `newtype T :: Id Type` is rejected: a
  newtype's final kind always has the form TYPE r, just as we want.

Note that this is possible in the H98 case only for a data family, because
the H98 syntax doesn't permit a kind signature on the newtype itself.

There are also some changes for dealing with families:

1. In tcFamDecl1, we suppress a tcIsLiftedTypeKind check if
   UnliftedNewtypes is on. This allows us to write things like:
     data family Foo :: TYPE 'IntRep

2. In a newtype instance (with -XUnliftedNewtypes), if the user does
   not write a kind signature, we want to allow the possibility that
   the kind is not Type, so we use newOpenTypeKind instead of liftedTypeKind.
   This is done in tcDataFamInstHeader in GHC.Tc.TyCl.Instance. Example:

       data family Bar (a :: RuntimeRep) :: TYPE a
       newtype instance Bar 'IntRep = BarIntC Int#
       newtype instance Bar 'WordRep :: TYPE 'WordRep where
         BarWordC :: Word# -> Bar 'WordRep

   The data instance corresponding to IntRep does not specify a kind signature,
   so tc_kind_sig just returns `TYPE r0` (where `r0` is a fresh metavariable).
   The data instance corresponding to WordRep does have a kind signature, so
   we use that kind signature.

3. A data family and its newtype instance may be declared with slightly
   different kinds. See point DF6 in Note [Data family/instance return kinds]

There's also a change in the renamer:

* In GHC.RenameSource.rnTyClDecl, enabling UnliftedNewtypes changes what is means
  for a newtype to have a CUSK. This is necessary since UnliftedNewtypes
  means that, for newtypes without kind signatures, we must use the field
  inside the data constructor to determine the result kind.
  See Note [Unlifted Newtypes and CUSKs] for more detail.

For completeness, it was also necessary to make coerce work on
unlifted types, resolving #13595.

<Error Messages>: It's tempting to think that the expected kind for a newtype
constructor argument when -XUnliftedNewtypes is *not* enabled should just be Type.
But this leads to difficulty in suggesting to enable UnliftedNewtypes. Here is
an example:

  newtype A = MkA Int#

If we expect the argument to MkA to have kind Type, then we get a kind-mismatch
error. The problem is that there is no way to connect this mismatch error to
-XUnliftedNewtypes, and suggest enabling the extension. So, instead, we allow
the A to type-check, but then find the problem when doing validity checking (and
where we get make a suitable error message). One potential worry is

  {-# LANGUAGE PolyKinds #-}
  newtype B a = MkB a

This turns out OK, because unconstrained RuntimeReps default to LiftedRep, just
as we would like. Another potential problem comes in a case like

  -- no UnliftedNewtypes

  data family D :: k
  newtype instance D = MkD Any

Here, we want inference to tell us that k should be instantiated to Type in
the instance. With the approach described here (checking for Type only in
the validity checker), that will not happen. But I cannot think of a non-contrived
example that will notice this lack of inference, so it seems better to improve
error messages than be able to infer this instantiation.

Note [Implementation of UnliftedDatatypes]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Expected behavior of UnliftedDatatypes:

* Proposal: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0265-unlifted-datatypes.rst
* Discussion: https://github.com/ghc-proposals/ghc-proposals/pull/265

The implementation heavily leans on Note [Implementation of UnliftedNewtypes].

In the frontend, the following tweaks have been made in the typechecker:

* STEP 1: In the inferInitialKinds phase, newExpectedKind gives data type
  constructors a result kind of `TYPE r` with a fresh unification variable
  `r :: RuntimeRep` when there is a SAKS. (Same as for UnliftedNewtypes.)
  Not needed with a CUSK, because it can't specify result kinds.
  If there's a GADTSyntax result kind signature, we keep on using that kind.

  Similarly, for data instances without a kind signature, we use
  `TYPE r` as the result kind, to support the following code:

    data family F a :: UnliftedType
    data instance F Int = TInt

  The omission of a kind signature for `F` should not mean a result kind
  of `Type` (and thus a kind error) here.

* STEP 2: No change to kcTyClDecl.

* STEP 3: In GHC.Tc.Gen.HsType.checkDataKindSig, we make sure that the result
  kind of the data declaration is actually `Type` or `TYPE (BoxedRep l)`,
  for some `l`. If UnliftedDatatypes is not activated, we emit an error with a
  suggestion in the latter case.

  Why not start out with `TYPE (BoxedRep l)` in the first place? Because then
  we get worse kind error messages in e.g. saks_fail010:

     -     Couldn't match expected kind: TYPE ('GHC.Types.BoxedRep t0)
     -                  with actual kind: * -> *
     +     Expected a type, but found something with kind ‘* -> *’
           In the data type declaration for ‘T’

  It seems `TYPE r` already has appropriate pretty-printing support.

The changes to Core, STG and Cmm are of rather cosmetic nature.
The IRs are already well-equipped to handle unlifted types, and unlifted
datatypes are just a new sub-class thereof.
-}

tcTyClDecl :: RolesInfo -> LTyClDecl GhcRn -> TcM ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
tcTyClDecl :: (Name -> [Role])
-> LTyClDecl GhcRn
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
tcTyClDecl Name -> [Role]
roles_info (L SrcSpanAnnA
loc TyClDecl GhcRn
decl)
  | Just TyThing
thing <- Name -> Maybe TyThing
wiredInNameTyThing_maybe (TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl)
  = case TyThing
thing of -- See Note [Declarations for wired-in things]
      ATyCon TyCon
tc -> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ((TyCon
tc, []), TyCon -> TyClDecl GhcRn -> [DerivInfo]
wiredInDerivInfo TyCon
tc TyClDecl GhcRn
decl)
      TyThing
_ -> String
-> SDoc
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tcTyClDecl" (TyThing -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyThing
thing)

  | Bool
otherwise
  = SrcSpanAnnA
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (IOEnv
   (Env TcGblEnv TcLclEnv)
   ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b. (a -> b) -> a -> b
$ TyClDecl GhcRn
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. TyClDecl GhcRn -> TcM a -> TcM a
tcAddDeclCtxt TyClDecl GhcRn
decl (IOEnv
   (Env TcGblEnv TcLclEnv)
   ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"---- tcTyClDecl ---- {" (TyClDecl GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyClDecl GhcRn
decl)
       ; (tc_vi@(tc, _), deriv_infos) <- Maybe Class
-> (Name -> [Role])
-> TyClDecl GhcRn
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
tcTyClDecl1 Maybe Class
forall a. Maybe a
Nothing Name -> [Role]
roles_info TyClDecl GhcRn
decl
       ; traceTc "---- tcTyClDecl end ---- }" (ppr tc)
       ; return (tc_vi, deriv_infos) }

noDerivInfos :: a -> (a, [DerivInfo])
noDerivInfos :: forall a. a -> (a, [DerivInfo])
noDerivInfos a
a = (a
a, [])

noEqnValidityInfos :: a -> (a, [TyFamEqnValidityInfo])
noEqnValidityInfos :: forall a. a -> (a, [TyFamEqnValidityInfo])
noEqnValidityInfos a
a = (a
a, [])

wiredInDerivInfo :: TyCon -> TyClDecl GhcRn -> [DerivInfo]
wiredInDerivInfo :: TyCon -> TyClDecl GhcRn -> [DerivInfo]
wiredInDerivInfo TyCon
tycon TyClDecl GhcRn
decl
  | DataDecl { tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn GhcRn
dataDefn } <- TyClDecl GhcRn
decl
  , HsDataDefn { dd_derivs :: forall pass. HsDataDefn pass -> HsDeriving pass
dd_derivs = HsDeriving GhcRn
derivs } <- HsDataDefn GhcRn
dataDefn
  = [ DerivInfo { di_rep_tc :: TyCon
di_rep_tc = TyCon
tycon
                , di_scoped_tvs :: [(Name, Var)]
di_scoped_tvs =
                    if TyCon -> Bool
isPrimTyCon TyCon
tycon
                       then []  -- no tyConTyVars
                       else [Var] -> [(Name, Var)]
mkTyVarNamePairs (TyCon -> [Var]
tyConTyVars TyCon
tycon)
                , di_clauses :: HsDeriving GhcRn
di_clauses = HsDeriving GhcRn
derivs
                , di_ctxt :: SDoc
di_ctxt = TyClDecl GhcRn -> SDoc
tcMkDeclCtxt TyClDecl GhcRn
decl } ]
wiredInDerivInfo TyCon
_ TyClDecl GhcRn
_ = []

  -- "type family" declarations
tcTyClDecl1 :: Maybe Class -> RolesInfo -> TyClDecl GhcRn -> TcM ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
tcTyClDecl1 :: Maybe Class
-> (Name -> [Role])
-> TyClDecl GhcRn
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
tcTyClDecl1 Maybe Class
parent Name -> [Role]
_roles_info (FamDecl { tcdFam :: forall pass. TyClDecl pass -> FamilyDecl pass
tcdFam = FamilyDecl GhcRn
fd })
  = ((TyCon, [TyFamEqnValidityInfo])
 -> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b.
(a -> b)
-> IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (TyCon, [TyFamEqnValidityInfo])
-> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. a -> (a, [DerivInfo])
noDerivInfos (IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    Maybe Class
-> FamilyDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
tcFamDecl1 Maybe Class
parent FamilyDecl GhcRn
fd

  -- "type" synonym declaration
tcTyClDecl1 Maybe Class
_parent Name -> [Role]
roles_info
            (SynDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
tc_name
                     , tcdRhs :: forall pass. TyClDecl pass -> LHsType pass
tcdRhs   = LHsKind GhcRn
rhs })
  = Bool
-> ((TyCon -> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
    -> TcRn TyCon
    -> IOEnv
         (Env TcGblEnv TcLclEnv)
         ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> (TyCon -> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> TcRn TyCon
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. HasCallStack => Bool -> a -> a
assert (Maybe Class -> Bool
forall a. Maybe a -> Bool
isNothing Maybe Class
_parent )
    (TyCon -> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> TcRn TyCon
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b.
(a -> b)
-> IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap ( (TyCon, [TyFamEqnValidityInfo])
-> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. a -> (a, [DerivInfo])
noDerivInfos ((TyCon, [TyFamEqnValidityInfo])
 -> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> (TyCon -> (TyCon, [TyFamEqnValidityInfo]))
-> TyCon
-> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TyCon -> (TyCon, [TyFamEqnValidityInfo])
forall a. a -> (a, [TyFamEqnValidityInfo])
noEqnValidityInfos ) (TcRn TyCon
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> TcRn TyCon
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    (Name -> [Role]) -> Name -> LHsKind GhcRn -> TcRn TyCon
tcTySynRhs Name -> [Role]
roles_info Name
tc_name LHsKind GhcRn
rhs

  -- "data/newtype" declaration
tcTyClDecl1 Maybe Class
_parent Name -> [Role]
roles_info
            decl :: TyClDecl GhcRn
decl@(DataDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
tc_name
                           , tcdDataDefn :: forall pass. TyClDecl pass -> HsDataDefn pass
tcdDataDefn = HsDataDefn GhcRn
defn })
  = Bool
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. HasCallStack => Bool -> a -> a
assert (Maybe Class -> Bool
forall a. Maybe a -> Bool
isNothing Maybe Class
_parent) (IOEnv
   (Env TcGblEnv TcLclEnv)
   ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    ((TyCon, [DerivInfo])
 -> ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b.
(a -> b)
-> IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (\(TyCon
tc, [DerivInfo]
deriv_info) -> ((TyCon
tc, []), [DerivInfo]
deriv_info)) (IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    SDoc
-> (Name -> [Role])
-> Name
-> HsDataDefn GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcDataDefn (TyClDecl GhcRn -> SDoc
tcMkDeclCtxt TyClDecl GhcRn
decl) Name -> [Role]
roles_info Name
tc_name HsDataDefn GhcRn
defn

tcTyClDecl1 Maybe Class
_parent Name -> [Role]
roles_info
            (ClassDecl { tcdLName :: forall pass. TyClDecl pass -> LIdP pass
tcdLName = L SrcSpanAnnN
_ Name
class_name
                       , tcdCtxt :: forall pass. TyClDecl pass -> Maybe (LHsContext pass)
tcdCtxt = Maybe (LHsContext GhcRn)
hs_ctxt
                       , tcdMeths :: forall pass. TyClDecl pass -> LHsBinds pass
tcdMeths = LHsBinds GhcRn
meths
                       , tcdFDs :: forall pass. TyClDecl pass -> [LHsFunDep pass]
tcdFDs = [LHsFunDep GhcRn]
fundeps
                       , tcdSigs :: forall pass. TyClDecl pass -> [LSig pass]
tcdSigs = [LSig GhcRn]
sigs
                       , tcdATs :: forall pass. TyClDecl pass -> [LFamilyDecl pass]
tcdATs = [LFamilyDecl GhcRn]
ats
                       , tcdATDefs :: forall pass. TyClDecl pass -> [LTyFamDefltDecl pass]
tcdATDefs = [LTyFamDefltDecl GhcRn]
at_defs })
  = Bool
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a. HasCallStack => Bool -> a -> a
assert (Maybe Class -> Bool
forall a. Maybe a -> Bool
isNothing Maybe Class
_parent) (IOEnv
   (Env TcGblEnv TcLclEnv)
   ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ((TyCon, [TyFamEqnValidityInfo]), [DerivInfo])
forall a b. (a -> b) -> a -> b
$
    do { clas <- (Name -> [Role])
-> Name
-> Maybe (LHsContext GhcRn)
-> LHsBinds GhcRn
-> [LHsFunDep GhcRn]
-> [LSig GhcRn]
-> [LFamilyDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> TcM Class
tcClassDecl1 Name -> [Role]
roles_info Name
class_name Maybe (LHsContext GhcRn)
hs_ctxt
                              LHsBinds GhcRn
meths [LHsFunDep GhcRn]
fundeps [LSig GhcRn]
sigs [LFamilyDecl GhcRn]
ats [LTyFamDefltDecl GhcRn]
at_defs
       ; return (noDerivInfos $ noEqnValidityInfos (classTyCon clas)) }


{- *********************************************************************
*                                                                      *
          Class declarations
*                                                                      *
********************************************************************* -}

tcClassDecl1 :: RolesInfo -> Name -> Maybe (LHsContext GhcRn)
             -> LHsBinds GhcRn -> [LHsFunDep GhcRn] -> [LSig GhcRn]
             -> [LFamilyDecl GhcRn] -> [LTyFamDefltDecl GhcRn]
             -> TcM Class
tcClassDecl1 :: (Name -> [Role])
-> Name
-> Maybe (LHsContext GhcRn)
-> LHsBinds GhcRn
-> [LHsFunDep GhcRn]
-> [LSig GhcRn]
-> [LFamilyDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> TcM Class
tcClassDecl1 Name -> [Role]
roles_info Name
class_name Maybe (LHsContext GhcRn)
hs_ctxt LHsBinds GhcRn
meths [LHsFunDep GhcRn]
fundeps [LSig GhcRn]
sigs [LFamilyDecl GhcRn]
ats [LTyFamDefltDecl GhcRn]
at_defs
  = (Class -> TcM Class) -> TcM Class
forall a env. (a -> IOEnv env a) -> IOEnv env a
fixM ((Class -> TcM Class) -> TcM Class)
-> (Class -> TcM Class) -> TcM Class
forall a b. (a -> b) -> a -> b
$ \ Class
clas -> -- We need the knot because 'clas' is passed into tcClassATs
    Name -> ([TyConBinder] -> Type -> TcM Class) -> TcM Class
forall a. Name -> ([TyConBinder] -> Type -> TcM a) -> TcM a
bindTyClTyVars Name
class_name (([TyConBinder] -> Type -> TcM Class) -> TcM Class)
-> ([TyConBinder] -> Type -> TcM Class) -> TcM Class
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
tc_bndrs Type
res_kind ->
    do { Type -> TcRn ()
checkClassKindSig Type
res_kind
       ; String -> SDoc -> TcRn ()
traceTc String
"tcClassDecl 1" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
class_name SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
tc_bndrs)
       ; let tycon_name :: Name
tycon_name = Name
class_name        -- We use the same name
             roles :: [Role]
roles = Name -> [Role]
roles_info Name
tycon_name  -- for TyCon and Class

       ; (ctxt, fds, sig_stuff, at_stuff)
            <- SkolemInfoAnon
-> [TyConBinder]
-> TcM (ThetaType, [([Var], [Var])], [TcMethInfo], [ClassATItem])
-> TcM (ThetaType, [([Var], [Var])], [TcMethInfo], [ClassATItem])
forall a. SkolemInfoAnon -> [TyConBinder] -> TcM a -> TcM a
pushLevelAndSolveEqualities SkolemInfoAnon
skol_info [TyConBinder]
tc_bndrs (TcM (ThetaType, [([Var], [Var])], [TcMethInfo], [ClassATItem])
 -> TcM (ThetaType, [([Var], [Var])], [TcMethInfo], [ClassATItem]))
-> TcM (ThetaType, [([Var], [Var])], [TcMethInfo], [ClassATItem])
-> TcM (ThetaType, [([Var], [Var])], [TcMethInfo], [ClassATItem])
forall a b. (a -> b) -> a -> b
$
               -- The (binderVars tc_bndrs) is needed bring into scope the
               -- skolems bound by the class decl header (#17841)
               do { ctxt <- Maybe (LHsContext GhcRn) -> TcM ThetaType
tcHsContext Maybe (LHsContext GhcRn)
hs_ctxt
                  ; fds  <- mapM (addLocM tc_fundep) fundeps
                  ; sig_stuff <- tcClassSigs class_name sigs meths
                  ; at_stuff  <- tcClassATs class_name clas ats at_defs
                  ; return (ctxt, fds, sig_stuff, at_stuff) }

       -- See Note [Error on unconstrained meta-variables] in GHC.Tc.Utils.TcMType
       -- Example: (typecheck/should_fail/T17562)
       --   type C :: Type -> Type -> Constraint
       --   class (forall a. a b ~ a c) => C b c
       -- The kind of `a` is unconstrained.
       ; dvs <- candidateQTyVarsOfTypes ctxt
       ; let err_ctx TidyEnv
tidy_env = do { (tidy_env2, ctxt) <- TidyEnv -> ThetaType -> ZonkM (TidyEnv, ThetaType)
zonkTidyTcTypes TidyEnv
tidy_env ThetaType
ctxt
                                   ; return (tidy_env2, UninfTyCtx_ClassContext ctxt) }
       ; doNotQuantifyTyVars dvs err_ctx

       -- The pushLevelAndSolveEqualities will report errors for any
       -- unsolved equalities, so these zonks should not encounter
       -- any unfilled coercion variables unless there is such an error
       -- The zonk also squeeze out the TcTyCons, and converts
       -- Skolems to tyvars.
       ; (bndrs, ctxt, sig_stuff) <- initZonkEnv NoFlexi $
         runZonkBndrT (zonkTyVarBindersX tc_bndrs) $ \ [TyConBinder]
bndrs ->
           do { ctxt        <- ThetaType -> ZonkTcM ThetaType
zonkTcTypesToTypesX ThetaType
ctxt
              ; sig_stuff   <- mapM zonkTcMethInfoToMethInfoX sig_stuff
                -- ToDo: do we need to zonk at_stuff?
              ; return (bndrs, ctxt, sig_stuff) }

       -- TODO: Allow us to distinguish between abstract class,
       -- and concrete class with no methods (maybe by
       -- specifying a trailing where or not

       ; mindef <- tcClassMinimalDef class_name sigs sig_stuff
       ; is_boot <- tcIsHsBootOrSig
       ; let body | Bool
is_boot, Maybe
  (GenLocated SrcSpanAnnC [GenLocated SrcSpanAnnA (HsType GhcRn)])
-> Bool
forall a. Maybe a -> Bool
isNothing Maybe (LHsContext GhcRn)
Maybe
  (GenLocated SrcSpanAnnC [GenLocated SrcSpanAnnA (HsType GhcRn)])
hs_ctxt, [ClassATItem] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [ClassATItem]
at_stuff, [TcMethInfo] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TcMethInfo]
sig_stuff
                  -- We use @isNothing hs_ctxt@ rather than @null ctxt@,
                  -- so that a declaration in an hs-boot file such as:
                  --
                  -- class () => C a b | a -> b
                  --
                  -- is not considered abstract; it's sometimes useful
                  -- to be able to declare such empty classes in hs-boot files.
                  -- See #20661.
                  = Maybe (ThetaType, [ClassATItem], [TcMethInfo], ClassMinimalDef)
forall a. Maybe a
Nothing
                  | Bool
otherwise
                  = (ThetaType, [ClassATItem], [TcMethInfo], ClassMinimalDef)
-> Maybe (ThetaType, [ClassATItem], [TcMethInfo], ClassMinimalDef)
forall a. a -> Maybe a
Just (ThetaType
ctxt, [ClassATItem]
at_stuff, [TcMethInfo]
sig_stuff, ClassMinimalDef
mindef)

       ; clas <- buildClass class_name bndrs roles fds body
       ; traceTc "tcClassDecl" (ppr fundeps $$ ppr bndrs $$
                                ppr fds)
       ; return clas }
  where
    skol_info :: SkolemInfoAnon
skol_info = TyConFlavour TyCon -> Name -> SkolemInfoAnon
TyConSkol TyConFlavour TyCon
forall tc. TyConFlavour tc
ClassFlavour Name
class_name

    tc_fundep :: GHC.Hs.FunDep GhcRn -> TcM ([Var],[Var])
    tc_fundep :: FunDep GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) ([Var], [Var])
tc_fundep (FunDep XCFunDep GhcRn
_ [LIdP GhcRn]
tvs1 [LIdP GhcRn]
tvs2)
                           = do { tvs1' <- (LocatedN Name -> IOEnv (Env TcGblEnv TcLclEnv) Var)
-> [LocatedN Name] -> TcM [Var]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM (Name -> IOEnv (Env TcGblEnv TcLclEnv) Var
tcLookupTyVar (Name -> IOEnv (Env TcGblEnv TcLclEnv) Var)
-> (LocatedN Name -> Name)
-> LocatedN Name
-> IOEnv (Env TcGblEnv TcLclEnv) Var
forall b c a. (b -> c) -> (a -> b) -> a -> c
. LocatedN Name -> Name
forall l e. GenLocated l e -> e
unLoc) [LIdP GhcRn]
[LocatedN Name]
tvs1 ;
                                ; tvs2' <- mapM (tcLookupTyVar . unLoc) tvs2 ;
                                ; return (tvs1',tvs2') }


{- Note [Associated type defaults]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following is an example of associated type defaults:

  class C a where
    data D a

    type F a b :: *
    type F a b = [a]        -- Default

Note that we can get default definitions only for type families, not data
families.
-}

tcClassATs :: Name                    -- The class name (not knot-tied)
           -> Class                   -- The class parent of this associated type
           -> [LFamilyDecl GhcRn]     -- Associated types.
           -> [LTyFamDefltDecl GhcRn] -- Associated type defaults.
           -> TcM [ClassATItem]
tcClassATs :: Name
-> Class
-> [LFamilyDecl GhcRn]
-> [LTyFamDefltDecl GhcRn]
-> TcM [ClassATItem]
tcClassATs Name
class_name Class
cls [LFamilyDecl GhcRn]
ats [LTyFamDefltDecl GhcRn]
at_defs
  = do {  -- Complain about associated type defaults for non associated-types
         [IOEnv (Env TcGblEnv TcLclEnv) Any] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a.
(Foldable t, Monad m) =>
t (m a) -> m ()
sequence_ [ TcRnMessage -> IOEnv (Env TcGblEnv TcLclEnv) Any
forall a. TcRnMessage -> TcM a
failWithTc (TcRnMessage -> IOEnv (Env TcGblEnv TcLclEnv) Any)
-> TcRnMessage -> IOEnv (Env TcGblEnv TcLclEnv) Any
forall a b. (a -> b) -> a -> b
$ IllegalInstanceReason -> TcRnMessage
TcRnIllegalInstance
                                (IllegalInstanceReason -> TcRnMessage)
-> IllegalInstanceReason -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ IllegalFamilyInstanceReason -> IllegalInstanceReason
IllegalFamilyInstance (IllegalFamilyInstanceReason -> IllegalInstanceReason)
-> IllegalFamilyInstanceReason -> IllegalInstanceReason
forall a b. (a -> b) -> a -> b
$ InvalidAssoc -> IllegalFamilyInstanceReason
InvalidAssoc
                                (InvalidAssoc -> IllegalFamilyInstanceReason)
-> InvalidAssoc -> IllegalFamilyInstanceReason
forall a b. (a -> b) -> a -> b
$ InvalidAssocDefault -> InvalidAssoc
InvalidAssocDefault
                                (InvalidAssocDefault -> InvalidAssoc)
-> InvalidAssocDefault -> InvalidAssoc
forall a b. (a -> b) -> a -> b
$ Name -> Name -> InvalidAssocDefault
AssocDefaultNotAssoc Name
class_name Name
n
                   | Name
n <- (GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn) -> Name)
-> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map LTyFamDefltDecl GhcRn -> Name
GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn) -> Name
at_def_tycon [LTyFamDefltDecl GhcRn]
[GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
at_defs
                   , Bool -> Bool
not (Name
n Name -> NameSet -> Bool
`elemNameSet` NameSet
at_names) ]
       ; (GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
 -> IOEnv (Env TcGblEnv TcLclEnv) ClassATItem)
-> [GenLocated SrcSpanAnnA (FamilyDecl GhcRn)] -> TcM [ClassATItem]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) ClassATItem
tc_at [LFamilyDecl GhcRn]
[GenLocated SrcSpanAnnA (FamilyDecl GhcRn)]
ats }
  where
    at_def_tycon :: LTyFamDefltDecl GhcRn -> Name
    at_def_tycon :: LTyFamDefltDecl GhcRn -> Name
at_def_tycon = TyFamInstDecl GhcRn -> IdP GhcRn
TyFamInstDecl GhcRn -> Name
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyFamInstDecl (GhcPass p) -> IdP (GhcPass p)
tyFamInstDeclName (TyFamInstDecl GhcRn -> Name)
-> (GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)
    -> TyFamInstDecl GhcRn)
-> GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)
-> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn) -> TyFamInstDecl GhcRn
forall l e. GenLocated l e -> e
unLoc

    at_fam_name :: LFamilyDecl GhcRn -> Name
    at_fam_name :: LFamilyDecl GhcRn -> Name
at_fam_name = FamilyDecl GhcRn -> IdP GhcRn
FamilyDecl GhcRn -> Name
forall (p :: Pass). FamilyDecl (GhcPass p) -> IdP (GhcPass p)
familyDeclName (FamilyDecl GhcRn -> Name)
-> (GenLocated SrcSpanAnnA (FamilyDecl GhcRn) -> FamilyDecl GhcRn)
-> GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
-> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. GenLocated SrcSpanAnnA (FamilyDecl GhcRn) -> FamilyDecl GhcRn
forall l e. GenLocated l e -> e
unLoc

    at_names :: NameSet
at_names = [Name] -> NameSet
mkNameSet ((GenLocated SrcSpanAnnA (FamilyDecl GhcRn) -> Name)
-> [GenLocated SrcSpanAnnA (FamilyDecl GhcRn)] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map LFamilyDecl GhcRn -> Name
GenLocated SrcSpanAnnA (FamilyDecl GhcRn) -> Name
at_fam_name [LFamilyDecl GhcRn]
[GenLocated SrcSpanAnnA (FamilyDecl GhcRn)]
ats)

    at_defs_map :: NameEnv [LTyFamDefltDecl GhcRn]
    -- Maps an AT in 'ats' to a list of all its default defs in 'at_defs'
    at_defs_map :: NameEnv [LTyFamDefltDecl GhcRn]
at_defs_map = (GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)
 -> NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
 -> NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)])
-> NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (\GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)
at_def NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
nenv -> ([GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
 -> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
 -> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)])
-> NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> Name
-> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
forall a. (a -> a -> a) -> NameEnv a -> Name -> a -> NameEnv a
extendNameEnv_C [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
forall a. [a] -> [a] -> [a]
(++) NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
nenv
                                          (LTyFamDefltDecl GhcRn -> Name
at_def_tycon LTyFamDefltDecl GhcRn
GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)
at_def) [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)
at_def])
                        NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
forall a. NameEnv a
emptyNameEnv [LTyFamDefltDecl GhcRn]
[GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
at_defs

    tc_at :: GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) ClassATItem
tc_at GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
at = do { (fam_tc, val_infos) <- (FamilyDecl GhcRn
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
-> GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
forall t a b. HasLoc t => (a -> TcM b) -> GenLocated t a -> TcM b
addLocM (Maybe Class
-> FamilyDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
tcFamDecl1 (Class -> Maybe Class
forall a. a -> Maybe a
Just Class
cls)) GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
at
                  ; mapM_ (checkTyFamEqnValidityInfo fam_tc) val_infos
                  ; let at_defs = NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> Name -> Maybe [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv [LTyFamDefltDecl GhcRn]
NameEnv [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
at_defs_map (LFamilyDecl GhcRn -> Name
at_fam_name LFamilyDecl GhcRn
GenLocated SrcSpanAnnA (FamilyDecl GhcRn)
at)
                                  Maybe [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
-> [GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)]
forall a. Maybe a -> a -> a
`orElse` []
                  ; atd <- tcDefaultAssocDecl fam_tc at_defs
                  ; return (ATI fam_tc atd) }

-------------------------
tcDefaultAssocDecl ::
     TyCon                                             -- ^ Family TyCon (not knot-tied)
  -> [LTyFamDefltDecl GhcRn]                           -- ^ Defaults
  -> TcM (Maybe (KnotTied Type, TyFamEqnValidityInfo)) -- ^ Type checked RHS
tcDefaultAssocDecl :: TyCon
-> [LTyFamDefltDecl GhcRn]
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
tcDefaultAssocDecl TyCon
_ []
  = Maybe (Type, TyFamEqnValidityInfo)
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Maybe (Type, TyFamEqnValidityInfo)
forall a. Maybe a
Nothing  -- No default declaration

tcDefaultAssocDecl TyCon
_ (LTyFamDefltDecl GhcRn
d1:LTyFamDefltDecl GhcRn
_:[LTyFamDefltDecl GhcRn]
_)
  = TcRnMessage -> TcM (Maybe (Type, TyFamEqnValidityInfo))
forall a. TcRnMessage -> TcM a
failWithTc (TcRnMessage -> TcM (Maybe (Type, TyFamEqnValidityInfo)))
-> TcRnMessage -> TcM (Maybe (Type, TyFamEqnValidityInfo))
forall a b. (a -> b) -> a -> b
$ IllegalInstanceReason -> TcRnMessage
TcRnIllegalInstance (IllegalInstanceReason -> TcRnMessage)
-> IllegalInstanceReason -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ IllegalFamilyInstanceReason -> IllegalInstanceReason
IllegalFamilyInstance
               (IllegalFamilyInstanceReason -> IllegalInstanceReason)
-> IllegalFamilyInstanceReason -> IllegalInstanceReason
forall a b. (a -> b) -> a -> b
$ InvalidAssoc -> IllegalFamilyInstanceReason
InvalidAssoc (InvalidAssoc -> IllegalFamilyInstanceReason)
-> InvalidAssoc -> IllegalFamilyInstanceReason
forall a b. (a -> b) -> a -> b
$ InvalidAssocDefault -> InvalidAssoc
InvalidAssocDefault (InvalidAssocDefault -> InvalidAssoc)
-> InvalidAssocDefault -> InvalidAssoc
forall a b. (a -> b) -> a -> b
$
      Name -> InvalidAssocDefault
AssocMultipleDefaults (TyFamInstDecl GhcRn -> IdP GhcRn
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyFamInstDecl (GhcPass p) -> IdP (GhcPass p)
tyFamInstDeclName (GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn) -> TyFamInstDecl GhcRn
forall l e. GenLocated l e -> e
unLoc LTyFamDefltDecl GhcRn
GenLocated SrcSpanAnnA (TyFamInstDecl GhcRn)
d1))

tcDefaultAssocDecl TyCon
fam_tc
  [L SrcSpanAnnA
loc (TyFamInstDecl { tfid_eqn :: forall pass. TyFamInstDecl pass -> TyFamInstEqn pass
tfid_eqn =
                            FamEqn { feqn_tycon :: forall pass rhs. FamEqn pass rhs -> LIdP pass
feqn_tycon = L SrcSpanAnnN
_ Name
tc_name
                                   , feqn_bndrs :: forall pass rhs. FamEqn pass rhs -> HsOuterFamEqnTyVarBndrs pass
feqn_bndrs = HsOuterFamEqnTyVarBndrs GhcRn
outer_bndrs
                                   , feqn_pats :: forall pass rhs. FamEqn pass rhs -> HsFamEqnPats pass
feqn_pats  = HsFamEqnPats GhcRn
hs_pats
                                   , feqn_rhs :: forall pass rhs. FamEqn pass rhs -> rhs
feqn_rhs   = LHsKind GhcRn
hs_rhs_ty }})]
  = -- See Note [Type-checking default assoc decls]
    SrcSpanAnnA
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcM (Maybe (Type, TyFamEqnValidityInfo))
 -> TcM (Maybe (Type, TyFamEqnValidityInfo)))
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
forall a b. (a -> b) -> a -> b
$
    SDoc
-> Name
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"default type instance") Name
tc_name (TcM (Maybe (Type, TyFamEqnValidityInfo))
 -> TcM (Maybe (Type, TyFamEqnValidityInfo)))
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
-> TcM (Maybe (Type, TyFamEqnValidityInfo))
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"tcDefaultAssocDecl 1" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name)
       ; let fam_tc_name :: Name
fam_tc_name = TyCon -> Name
tyConName TyCon
fam_tc
             vis_arity :: Int
vis_arity = [Var] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (TyCon -> [Var]
tyConVisibleTyVars TyCon
fam_tc)
             vis_pats :: Int
vis_pats  = [HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> Int
forall p tm ty. [HsArg p tm ty] -> Int
numVisibleArgs HsFamEqnPats GhcRn
[HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_pats

       -- Kind of family check
       ; Bool -> TcRn () -> TcRn ()
forall a. HasCallStack => Bool -> a -> a
assert (Name
fam_tc_name Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
tc_name) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         Bool -> TcRnMessage -> TcRn ()
checkTc (TyCon -> Bool
isTypeFamilyTyCon TyCon
fam_tc) (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         IllegalInstanceReason -> TcRnMessage
TcRnIllegalInstance (IllegalInstanceReason -> TcRnMessage)
-> IllegalInstanceReason -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ IllegalFamilyInstanceReason -> IllegalInstanceReason
IllegalFamilyInstance (IllegalFamilyInstanceReason -> IllegalInstanceReason)
-> IllegalFamilyInstanceReason -> IllegalInstanceReason
forall a b. (a -> b) -> a -> b
$
           TyCon -> IllegalFamilyInstanceReason
FamilyCategoryMismatch TyCon
fam_tc

       -- Arity check
       ; Bool -> TcRnMessage -> TcRn ()
checkTc (Int
vis_pats Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
vis_arity) (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         IllegalInstanceReason -> TcRnMessage
TcRnIllegalInstance (IllegalInstanceReason -> TcRnMessage)
-> IllegalInstanceReason -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ IllegalFamilyInstanceReason -> IllegalInstanceReason
IllegalFamilyInstance (IllegalFamilyInstanceReason -> IllegalInstanceReason)
-> IllegalFamilyInstanceReason -> IllegalInstanceReason
forall a b. (a -> b) -> a -> b
$
           TyCon -> Int -> IllegalFamilyInstanceReason
FamilyArityMismatch TyCon
fam_tc Int
vis_arity

       -- Typecheck RHS
       --
       -- You might think we should pass in some AssocInstInfo, as we're looking
       -- at an associated type. But this would be wrong, because an associated
       -- type default LHS can mention *different* type variables than the
       -- enclosing class. So it's treated more as a freestanding beast.
       ; (qtvs, non_user_tvs, pats, rhs_ty)
           <- TyCon
-> AssocInstInfo
-> HsOuterFamEqnTyVarBndrs GhcRn
-> HsFamEqnPats GhcRn
-> LHsKind GhcRn
-> TcM ([Var], VarSet, ThetaType, Type)
tcTyFamInstEqnGuts TyCon
fam_tc AssocInstInfo
NotAssociated
                HsOuterFamEqnTyVarBndrs GhcRn
outer_bndrs HsFamEqnPats GhcRn
hs_pats LHsKind GhcRn
hs_rhs_ty

       ; let fam_tvs = TyCon -> [Var]
tyConTyVars TyCon
fam_tc
       ; traceTc "tcDefaultAssocDecl 2" (vcat
           [ text "hs_pats"   <+> ppr hs_pats
           , text "hs_rhs_ty" <+> ppr hs_rhs_ty
           , text "fam_tvs" <+> ppr fam_tvs
           , text "qtvs"    <+> ppr qtvs
             -- NB: Do *not* print `pats` or rhs_ty here, as they can mention
             -- knot-tied TyCons. See #18648.
           ])
       ; let subst = case (Type -> Maybe Var) -> ThetaType -> Maybe [Var]
forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
forall (f :: * -> *) a b.
Applicative f =>
(a -> f b) -> [a] -> f [b]
traverse Type -> Maybe Var
getTyVar_maybe ThetaType
pats of
                       Just [Var]
cpt_tvs -> [Var] -> ThetaType -> Subst
HasDebugCallStack => [Var] -> ThetaType -> Subst
zipTvSubst [Var]
cpt_tvs ([Var] -> ThetaType
mkTyVarTys [Var]
fam_tvs)
                       Maybe [Var]
Nothing      -> Subst
emptySubst
                       -- The Nothing case can only be reached in invalid
                       -- associated type family defaults. In such cases, we
                       -- simply create an empty substitution and let GHC fall
                       -- over later, in GHC.Tc.Validity.checkValidAssocTyFamDeflt.
                       -- See Note [Type-checking default assoc decls].

       ; pure $ Just ( substTyUnchecked subst rhs_ty
                     , VI { vi_loc          = locA loc
                          , vi_qtvs         = qtvs
                          , vi_non_user_tvs = non_user_tvs
                          , vi_pats         = pats
                          , vi_rhs          = rhs_ty } )
           -- We perform checks for well-formedness and validity later, in
           -- GHC.Tc.Validity.checkValidAssocTyFamDeflt.
     }

{- Note [Type-checking default assoc decls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this default declaration for an associated type

   class C a where
      type F (a :: k) b :: Type
      type F (x :: j) y = Proxy x -> y

Note that the class variable 'a' doesn't scope over the default assoc
decl, nor do the type variables `k` and `b`. Instead, the default decl is
treated more like a top-level type instance. However, we store the default rhs
(Proxy x -> y) in F's TyCon, using F's own type variables, so we need to
convert it to (Proxy a -> b). We do this in the tcDefaultAssocDecl function by
creating a substitution [j |-> k, x |-> a, b |-> y] and applying this
substitution to the RHS.

In order to create this substitution, we must first ensure that all of
the arguments in the default instance consist of distinct type variables.
Checking for this property proves surprisingly tricky. Three potential places
where GHC could check for this property include:

1. Before typechecking (in the parser or renamer)
2. During typechecking (in tcDefaultAssocDecl)
3. After typechecking (using GHC.Tc.Validity)

Currently, GHC picks option (3) and implements this check using
GHC.Tc.Validity.checkValidAssocTyFamDeflt. GHC previously used options (1) and
(2), but neither option quite worked out for reasons that we will explain
shortly.

The first thing that checkValidAssocTyFamDeflt does is check that all arguments
in an associated type family default are type variables. As a motivating
example, consider this erroneous program (inspired by #11361):

   class C a where
      type F (a :: k) b :: Type
      type F x        b = x

If you squint, you'll notice that the kind of `x` is actually Type. However,
we cannot substitute from [Type |-> k], so we reject this default. This also
explains why GHC no longer implements option (1) above, since figuring out that
`x`'s kind is Type would be much more difficult without the knowledge that the
typechecker provides.

Next, checkValidAssocTyFamDeflt checks that all arguments are distinct. Here is
another offending example, this time taken from #13971:

   class C2 (a :: j) where
      type F2 (a :: j) (b :: k)
      type F2 (x :: z) y = SameKind x y
   data SameKind :: k -> k -> Type

All of the arguments in the default equation for `F2` are type variables, so
that passes the first check. However, if we were to build this substitution,
then both `j` and `k` map to `z`! In terms of visible kind application, it's as
if we had written `type F2 @z @z x y = SameKind @z x y`, which makes it clear
that we have duplicated a use of `z` on the LHS. Therefore, `F2`'s default is
also rejected.

There is one more design consideration in play here: what error message should
checkValidAssocTyFamDeflt produce if one of its checks fails? Ideally, it would
be something like this:

  Illegal duplicate variable ‘z’ in:
    ‘type F2 @z @z x y = ...’
    The arguments to ‘F2’ must all be distinct type variables

This requires printing out the arguments to the associated type family. This
can be dangerous, however. Consider this example, adapted from #18648:

  class C3 a where
     type F3 a
     type F3 (F3 a) = a

F3's default is illegal, since its argument is not a bare type variable. But
note that when we typecheck F3's default, the F3 type constructor is knot-tied.
Therefore, if we print the type `F3 a` in an error message, GHC will diverge!
This is the reason why GHC no longer implements option (2) above and instead
waits until /after/ typechecking has finished, at which point the typechecker
knot has been worked out.

As one final point, one might worry that the typechecker knot could cause the
substitution that tcDefaultAssocDecl creates to diverge, but this is not the
case. Since the LHS of a valid associated type family default is always just
variables, it won't contain any tycons. Accordingly, the patterns used in the
substitution won't actually be knot-tied, even though we're in the knot. (This
is too delicate for my taste, but it works.) If we're dealing with /invalid/
default, such as F3's above, then we simply create an empty substitution and
rely on checkValidAssocTyFamDeflt throwing an error message afterwards before
any damage is done.
-}

{- *********************************************************************
*                                                                      *
          Type family declarations
*                                                                      *
********************************************************************* -}

tcFamDecl1 :: Maybe Class -> FamilyDecl GhcRn -> TcM (TyCon, [TyFamEqnValidityInfo])
tcFamDecl1 :: Maybe Class
-> FamilyDecl GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
tcFamDecl1 Maybe Class
parent (FamilyDecl { fdInfo :: forall pass. FamilyDecl pass -> FamilyInfo pass
fdInfo = FamilyInfo GhcRn
fam_info
                              , fdLName :: forall pass. FamilyDecl pass -> LIdP pass
fdLName = tc_lname :: LIdP GhcRn
tc_lname@(L SrcSpanAnnN
_ Name
tc_name)
                              , fdResultSig :: forall pass. FamilyDecl pass -> LFamilyResultSig pass
fdResultSig = L EpAnnCO
_ FamilyResultSig GhcRn
sig
                              , fdInjectivityAnn :: forall pass. FamilyDecl pass -> Maybe (LInjectivityAnn pass)
fdInjectivityAnn = Maybe (LInjectivityAnn GhcRn)
inj })
  | FamilyInfo GhcRn
DataFamily <- FamilyInfo GhcRn
fam_info
  = Name
-> ([TyConBinder]
    -> Type
    -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
forall a. Name -> ([TyConBinder] -> Type -> TcM a) -> TcM a
bindTyClTyVarsAndZonk Name
tc_name (([TyConBinder]
  -> Type
  -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
-> ([TyConBinder]
    -> Type
    -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
tc_bndrs Type
res_kind -> do
  { String -> SDoc -> TcRn ()
traceTc String
"tcFamDecl1 data family:" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name)
  ; Name -> TcRn ()
checkFamFlag Name
tc_name

  -- Check that the result kind is OK
  -- We allow things like
  --   data family T (a :: Type) :: forall k. k -> Type
  -- We treat T as having arity 1, but result kind forall k. k -> Type
  -- But we want to check that the result kind finishes in
  --   Type or a kind-variable
  -- For the latter, consider
  --   data family D a :: forall k. Type -> k
  -- When UnliftedNewtypes is enabled, we loosen this restriction
  -- on the return kind. See Note [Implementation of UnliftedNewtypes], wrinkle (1).
  -- See also Note [Datatype return kinds]
  ; DataSort -> Type -> TcRn ()
checkDataKindSig DataSort
DataFamilySort Type
res_kind
  ; tc_rep_name <- Name -> TcRnIf TcGblEnv TcLclEnv Name
forall gbl lcl. Name -> TcRnIf gbl lcl Name
newTyConRepName Name
tc_name
  ; let inj   = [Bool] -> Injectivity
Injective ([Bool] -> Injectivity) -> [Bool] -> Injectivity
forall a b. (a -> b) -> a -> b
$ Int -> Bool -> [Bool]
forall a. Int -> a -> [a]
replicate ([TyConBinder] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [TyConBinder]
tc_bndrs) Bool
True
        tycon = Name
-> [TyConBinder]
-> Type
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
tc_name [TyConBinder]
tc_bndrs
                              Type
res_kind
                              (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig)
                              (Name -> FamTyConFlav
DataFamilyTyCon Name
tc_rep_name)
                              Maybe Class
parent Injectivity
inj
  ; return (tycon, []) }

  | FamilyInfo GhcRn
OpenTypeFamily <- FamilyInfo GhcRn
fam_info
  = Name
-> ([TyConBinder]
    -> Type
    -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
forall a. Name -> ([TyConBinder] -> Type -> TcM a) -> TcM a
bindTyClTyVarsAndZonk Name
tc_name (([TyConBinder]
  -> Type
  -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
-> ([TyConBinder]
    -> Type
    -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
tc_bndrs Type
res_kind -> do
  { String -> SDoc -> TcRn ()
traceTc String
"tcFamDecl1 open type family:" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name)
  ; Name -> TcRn ()
checkFamFlag Name
tc_name
  ; inj' <- [TyConBinder] -> Maybe (LInjectivityAnn GhcRn) -> TcM Injectivity
tcInjectivity [TyConBinder]
tc_bndrs Maybe (LInjectivityAnn GhcRn)
inj
  ; checkResultSigFlag tc_name sig  -- check after injectivity for better errors
  ; let tycon = Name
-> [TyConBinder]
-> Type
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
tc_name [TyConBinder]
tc_bndrs Type
res_kind
                               (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig) FamTyConFlav
OpenSynFamilyTyCon
                               Maybe Class
parent Injectivity
inj'
  ; return (tycon, []) }

  | ClosedTypeFamily Maybe [LTyFamInstEqn GhcRn]
mb_eqns <- FamilyInfo GhcRn
fam_info
  = -- Closed type families are a little tricky, because they contain the definition
    -- of both the type family and the equations for a CoAxiom.
    do { String -> SDoc -> TcRn ()
traceTc String
"tcFamDecl1 Closed type family:" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tc_name)
         -- the variables in the header scope only over the injectivity
         -- declaration but this is not involved here
       ; (inj', tc_bndrs, res_kind)
            <- Name
-> ([TyConBinder]
    -> Type -> TcM (Injectivity, [TyConBinder], Type))
-> TcM (Injectivity, [TyConBinder], Type)
forall a. Name -> ([TyConBinder] -> Type -> TcM a) -> TcM a
bindTyClTyVarsAndZonk Name
tc_name (([TyConBinder] -> Type -> TcM (Injectivity, [TyConBinder], Type))
 -> TcM (Injectivity, [TyConBinder], Type))
-> ([TyConBinder]
    -> Type -> TcM (Injectivity, [TyConBinder], Type))
-> TcM (Injectivity, [TyConBinder], Type)
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
tc_bndrs Type
res_kind ->
               do { inj' <- [TyConBinder] -> Maybe (LInjectivityAnn GhcRn) -> TcM Injectivity
tcInjectivity [TyConBinder]
tc_bndrs Maybe (LInjectivityAnn GhcRn)
inj
                  ; return (inj', tc_bndrs, res_kind) }

       ; checkFamFlag tc_name -- make sure we have -XTypeFamilies
       ; checkResultSigFlag tc_name sig

         -- If Nothing, this is an abstract family in a hs-boot file;
         -- but eqns might be empty in the Just case as well
       ; case mb_eqns of
           Maybe [LTyFamInstEqn GhcRn]
Nothing   ->
              let tc :: TyCon
tc = Name
-> [TyConBinder]
-> Type
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
tc_name [TyConBinder]
tc_bndrs Type
res_kind
                                     (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig)
                                     FamTyConFlav
AbstractClosedSynFamilyTyCon Maybe Class
parent
                                     Injectivity
inj'
              in (TyCon, [TyFamEqnValidityInfo])
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [TyFamEqnValidityInfo])
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon
tc, [])
           Just [LTyFamInstEqn GhcRn]
eqns -> do {

         -- Process the equations, creating CoAxBranches
       ; let tc_fam_tc :: TyCon
tc_fam_tc = Name
-> [TyConBinder]
-> Type
-> [(Name, Var)]
-> Bool
-> TyConFlavour TyCon
-> TyCon
mkTcTyCon Name
tc_name [TyConBinder]
tc_bndrs Type
res_kind
                                   [(Name, Var)]
noTcTyConScopedTyVars
                                   Bool
False {- this doesn't matter here -}
                                   TyConFlavour TyCon
forall tc. TyConFlavour tc
ClosedTypeFamilyFlavour

       ; (branches, axiom_validity_infos) <-
           [(KnotTied CoAxBranch, TyFamEqnValidityInfo)]
-> ([KnotTied CoAxBranch], [TyFamEqnValidityInfo])
forall a b. [(a, b)] -> ([a], [b])
unzip ([(KnotTied CoAxBranch, TyFamEqnValidityInfo)]
 -> ([KnotTied CoAxBranch], [TyFamEqnValidityInfo]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     [(KnotTied CoAxBranch, TyFamEqnValidityInfo)]
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ([KnotTied CoAxBranch], [TyFamEqnValidityInfo])
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (GenLocated
   SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))
 -> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo))
-> [GenLocated
      SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))]
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     [(KnotTied CoAxBranch, TyFamEqnValidityInfo)]
forall a b. (a -> TcRn b) -> [a] -> TcRn [b]
mapAndReportM (TyCon
-> AssocInstInfo
-> LTyFamInstEqn GhcRn
-> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo)
tcTyFamInstEqn TyCon
tc_fam_tc AssocInstInfo
NotAssociated) [LTyFamInstEqn GhcRn]
[GenLocated
   SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))]
eqns
         -- Do not attempt to drop equations dominated by earlier
         -- ones here; in the case of mutual recursion with a data
         -- type, we get a knot-tying failure.  Instead we check
         -- for this afterwards, in GHC.Tc.Validity.checkValidCoAxiom
         -- Example: tc265

         -- Create a CoAxiom, with the correct src location.
       ; co_ax_name <- newFamInstAxiomName tc_lname []

       ; let mb_co_ax
              | [GenLocated
   SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))]
-> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [LTyFamInstEqn GhcRn]
[GenLocated
   SrcSpanAnnA (FamEqn GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn)))]
eqns = Maybe (CoAxiom Branched)
forall a. Maybe a
Nothing   -- mkBranchedCoAxiom fails on empty list
              | Bool
otherwise = CoAxiom Branched -> Maybe (CoAxiom Branched)
forall a. a -> Maybe a
Just (Name -> TyCon -> [KnotTied CoAxBranch] -> CoAxiom Branched
mkBranchedCoAxiom Name
co_ax_name TyCon
fam_tc [KnotTied CoAxBranch]
branches)

             fam_tc = Name
-> [TyConBinder]
-> Type
-> Maybe Name
-> FamTyConFlav
-> Maybe Class
-> Injectivity
-> TyCon
mkFamilyTyCon Name
tc_name [TyConBinder]
tc_bndrs Type
res_kind (FamilyResultSig GhcRn -> Maybe (IdP GhcRn)
forall (a :: Pass).
FamilyResultSig (GhcPass a) -> Maybe (IdP (GhcPass a))
resultVariableName FamilyResultSig GhcRn
sig)
                      (Maybe (CoAxiom Branched) -> FamTyConFlav
ClosedSynFamilyTyCon Maybe (CoAxiom Branched)
mb_co_ax) Maybe Class
parent Injectivity
inj'

         -- We check for instance validity later, when doing validity
         -- checking for the tycon. Exception: checking equations
         -- overlap done by dropDominatedAxioms
       ; return (fam_tc, axiom_validity_infos) } }

-- | Maybe return a list of Bools that say whether a type family was declared
-- injective in the corresponding type arguments. Length of the list is equal to
-- the number of arguments (including implicit kind/coercion arguments).
-- True on position
-- N means that a function is injective in its Nth argument. False means it is
-- not.
tcInjectivity :: [TyConBinder] -> Maybe (LInjectivityAnn GhcRn)
              -> TcM Injectivity
tcInjectivity :: [TyConBinder] -> Maybe (LInjectivityAnn GhcRn) -> TcM Injectivity
tcInjectivity [TyConBinder]
_ Maybe (LInjectivityAnn GhcRn)
Nothing
  = Injectivity -> TcM Injectivity
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Injectivity
NotInjective

  -- User provided an injectivity annotation, so for each tyvar argument we
  -- check whether a type family was declared injective in that argument. We
  -- return a list of Bools, where True means that corresponding type variable
  -- was mentioned in lInjNames (type family is injective in that argument) and
  -- False means that it was not mentioned in lInjNames (type family is not
  -- injective in that type variable). We also extend injectivity information to
  -- kind variables, so if a user declares:
  --
  --   type family F (a :: k1) (b :: k2) = (r :: k3) | r -> a
  --
  -- then we mark both `a` and `k1` as injective.
  -- NB: the return kind is considered to be *input* argument to a type family.
  -- Since injectivity allows to infer input arguments from the result in theory
  -- we should always mark the result kind variable (`k3` in this example) as
  -- injective.  The reason is that result type has always an assigned kind and
  -- therefore we can always infer the result kind if we know the result type.
  -- But this does not seem to be useful in any way so we don't do it.  (Another
  -- reason is that the implementation would not be straightforward.)
tcInjectivity [TyConBinder]
tcbs (Just (L EpAnnCO
loc (InjectivityAnn XCInjectivityAnn GhcRn
_ LIdP GhcRn
_ [LIdP GhcRn]
lInjNames)))
  = EpAnnCO -> TcM Injectivity -> TcM Injectivity
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA EpAnnCO
loc (TcM Injectivity -> TcM Injectivity)
-> TcM Injectivity -> TcM Injectivity
forall a b. (a -> b) -> a -> b
$
    do { let tvs :: [Var]
tvs = [TyConBinder] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tcbs
       ; dflags <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       -- Fail eagerly to avoid reporting injectivity errors when
       -- TypeFamilyDependencies is not enabled.
       ; checkTc (xopt LangExt.TypeFamilyDependencies dflags)
                 TcRnTyFamDepsDisabled
       ; inj_tvs <- mapM (tcLookupTyVar . unLoc) lInjNames
       ; inj_tvs <- liftZonkM $ zonkTcTyVarsToTcTyVars inj_tvs -- zonk the kinds
       ; let inj_ktvs = (Var -> Bool) -> VarSet -> VarSet
filterVarSet Var -> Bool
isTyVar (VarSet -> VarSet) -> VarSet -> VarSet
forall a b. (a -> b) -> a -> b
$  -- no injective coercion vars
                        VarSet -> VarSet
closeOverKinds ([Var] -> VarSet
mkVarSet [Var]
inj_tvs)
       ; let inj_bools = (Var -> Bool) -> [Var] -> [Bool]
forall a b. (a -> b) -> [a] -> [b]
map (Var -> VarSet -> Bool
`elemVarSet` VarSet
inj_ktvs) [Var]
tvs
       ; traceTc "tcInjectivity" (vcat [ ppr tvs, ppr lInjNames, ppr inj_tvs
                                       , ppr inj_ktvs, ppr inj_bools ])
       ; return $ Injective inj_bools }

tcTySynRhs :: RolesInfo -> Name
           -> LHsType GhcRn -> TcM TyCon
tcTySynRhs :: (Name -> [Role]) -> Name -> LHsKind GhcRn -> TcRn TyCon
tcTySynRhs Name -> [Role]
roles_info Name
tc_name LHsKind GhcRn
hs_ty
  = Name -> ([TyConBinder] -> Type -> TcRn TyCon) -> TcRn TyCon
forall a. Name -> ([TyConBinder] -> Type -> TcM a) -> TcM a
bindTyClTyVars Name
tc_name (([TyConBinder] -> Type -> TcRn TyCon) -> TcRn TyCon)
-> ([TyConBinder] -> Type -> TcRn TyCon) -> TcRn TyCon
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
tc_bndrs Type
res_kind ->
    do { env <- TcRnIf TcGblEnv TcLclEnv TcLclEnv
forall gbl lcl. TcRnIf gbl lcl lcl
getLclEnv
       ; traceTc "tc-syn" (ppr tc_name $$ ppr (getLclEnvRdrEnv env))
       ; rhs_ty <- pushLevelAndSolveEqualities skol_info tc_bndrs $
                   tcCheckLHsType hs_ty (TheKind res_kind)

         -- See Note [Error on unconstrained meta-variables] in GHC.Tc.Utils.TcMType
         -- Example: (typecheck/should_fail/T17567)
         --   type T = forall a. Proxy a
         -- The kind of `a` is unconstrained.
       ; dvs <- candidateQTyVarsOfType rhs_ty
       ; let err_ctx TidyEnv
tidy_env = do { (tidy_env2, rhs_ty) <- TidyEnv -> Type -> ZonkM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env Type
rhs_ty
                                   ; return (tidy_env2, UninfTyCtx_TySynRhs rhs_ty) }
       ; doNotQuantifyTyVars dvs err_ctx

       ; (bndrs, rhs_ty) <- initZonkEnv NoFlexi $
         runZonkBndrT (zonkTyVarBindersX tc_bndrs) $ \ [TyConBinder]
bndrs ->
           do { rhs_ty <- Type -> ZonkTcM Type
zonkTcTypeToTypeX Type
rhs_ty
              ; return (bndrs, rhs_ty) }
       ; let roles = Name -> [Role]
roles_info Name
tc_name
       ; return (buildSynTyCon tc_name bndrs res_kind roles rhs_ty) }
  where
    skol_info :: SkolemInfoAnon
skol_info = TyConFlavour TyCon -> Name -> SkolemInfoAnon
TyConSkol TyConFlavour TyCon
forall tc. TyConFlavour tc
TypeSynonymFlavour Name
tc_name

tcDataDefn :: SDoc -> RolesInfo -> Name
           -> HsDataDefn GhcRn -> TcM (TyCon, [DerivInfo])
  -- NB: not used for newtype/data instances (whether associated or not)
tcDataDefn :: SDoc
-> (Name -> [Role])
-> Name
-> HsDataDefn GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
tcDataDefn SDoc
err_ctxt Name -> [Role]
roles_info Name
tc_name
           (HsDataDefn { dd_cType :: forall pass. HsDataDefn pass -> Maybe (XRec pass CType)
dd_cType = Maybe (XRec GhcRn CType)
cType
                       , dd_ctxt :: forall pass. HsDataDefn pass -> Maybe (LHsContext pass)
dd_ctxt = Maybe (LHsContext GhcRn)
ctxt
                       , dd_kindSig :: forall pass. HsDataDefn pass -> Maybe (LHsKind pass)
dd_kindSig = Maybe (LHsKind GhcRn)
mb_ksig  -- Already in tc's kind
                                               -- via inferInitialKinds
                       , dd_cons :: forall pass. HsDataDefn pass -> DataDefnCons (LConDecl pass)
dd_cons = DataDefnCons (LConDecl GhcRn)
cons
                       , dd_derivs :: forall pass. HsDataDefn pass -> HsDeriving pass
dd_derivs = HsDeriving GhcRn
derivs })
  = Name
-> ([TyConBinder]
    -> Type -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a. Name -> ([TyConBinder] -> Type -> TcM a) -> TcM a
bindTyClTyVars Name
tc_name (([TyConBinder]
  -> Type -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
 -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> ([TyConBinder]
    -> Type -> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo]))
-> IOEnv (Env TcGblEnv TcLclEnv) (TyCon, [DerivInfo])
forall a b. (a -> b) -> a -> b
$ \ [TyConBinder]
tc_bndrs Type
res_kind ->
       -- The TyCon tyvars must scope over
       --    - the stupid theta (dd_ctxt)
       --    - for H98 constructors only, the ConDecl
       -- But it does no harm to bring them into scope
       -- over GADT ConDecls as well; and it's awkward not to
    do { gadt_syntax <- Name
-> Maybe (LHsContext GhcRn)
-> DataDefnCons (LConDecl GhcRn)
-> TcRnIf TcGblEnv TcLclEnv Bool
dataDeclChecks Name
tc_name Maybe (LHsContext GhcRn)
ctxt DataDefnCons (LConDecl GhcRn)
cons

       ; tcg_env <- getGblEnv
       ; let hsc_src = TcGblEnv -> HscSource
tcg_src TcGblEnv
tcg_env
       ; unless (mk_permissive_kind hsc_src cons) $
         checkDataKindSig (DataDeclSort (dataDefnConsNewOrData cons)) res_kind

       ; stupid_tc_theta <- pushLevelAndSolveEqualities skol_info tc_bndrs $
                            tcHsContext ctxt

       -- See Note [Error on unconstrained meta-variables] in GHC.Tc.Utils.TcMType
       -- Example: (typecheck/should_fail/T17567StupidTheta)
       --   data (forall a. a b ~ a c) => T b c
       -- The kind of 'a' is unconstrained.
       ; dvs <- candidateQTyVarsOfTypes stupid_tc_theta
       ; let err_ctx TidyEnv
tidy_env
               = do { (tidy_env2, theta) <- TidyEnv -> ThetaType -> ZonkM (TidyEnv, ThetaType)
zonkTidyTcTypes TidyEnv
tidy_env ThetaType
stupid_tc_theta
                    ; return (tidy_env2, UninfTyCtx_DataContext theta) }
       ; doNotQuantifyTyVars dvs err_ctx

             -- Check that we don't use kind signatures without the extension
       ; kind_signatures <- xoptM LangExt.KindSignatures
       ; case mb_ksig of
          Just (L SrcSpanAnnA
_ HsType GhcRn
ksig)
            | Bool -> Bool
not Bool
kind_signatures
            -> TcRnMessage -> TcRn ()
addErrTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Either (HsType GhcPs) (Name, HsType GhcRn) -> TcRnMessage
TcRnKindSignaturesDisabled ((Name, HsType GhcRn) -> Either (HsType GhcPs) (Name, HsType GhcRn)
forall a b. b -> Either a b
Right (Name
tc_name, HsType GhcRn
ksig))
          Maybe (LHsKind GhcRn)
_ -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

       ; (bndrs, stupid_theta, res_kind) <- initZonkEnv NoFlexi $
         runZonkBndrT (zonkTyVarBindersX tc_bndrs) $ \ [TyConBinder]
bndrs ->
           do { stupid_theta   <- ThetaType -> ZonkTcM ThetaType
zonkTcTypesToTypesX ThetaType
stupid_tc_theta
              ; res_kind       <- zonkTcTypeToTypeX   res_kind
              ; return (bndrs, stupid_theta, res_kind) }

       ; tycon <- fixM $ \ TyCon
rec_tycon -> do
             { data_cons <- DataDeclInfo
-> TyCon
-> [TyConBinder]
-> Type
-> DataDefnCons (LConDecl GhcRn)
-> TcM (DataDefnCons DataCon)
tcConDecls DataDeclInfo
DDataType TyCon
rec_tycon [TyConBinder]
tc_bndrs Type
res_kind DataDefnCons (LConDecl GhcRn)
cons
             ; tc_rhs    <- mk_tc_rhs hsc_src rec_tycon data_cons
             ; tc_rep_nm <- newTyConRepName tc_name

             ; return (mkAlgTyCon tc_name
                                  bndrs
                                  res_kind
                                  (roles_info tc_name)
                                  (fmap unLoc cType)
                                  stupid_theta tc_rhs
                                  (VanillaAlgTyCon tc_rep_nm)
                                  gadt_syntax)
         }

       ; let scoped_tvs = [Var] -> [(Name, Var)]
mkTyVarNamePairs ([TyConBinder] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tc_bndrs)
                          -- scoped_tvs: still the skolem TcTyVars
             deriv_info = DerivInfo { di_rep_tc :: TyCon
di_rep_tc = TyCon
tycon
                                    , di_scoped_tvs :: [(Name, Var)]
di_scoped_tvs = [(Name, Var)]
scoped_tvs
                                    , di_clauses :: HsDeriving GhcRn
di_clauses = HsDeriving GhcRn
derivs
                                    , di_ctxt :: SDoc
di_ctxt = SDoc
err_ctxt }
       ; traceTc "tcDataDefn" (ppr tc_name $$ ppr tc_bndrs)
       ; return (tycon, [deriv_info]) }
  where
    skol_info :: SkolemInfoAnon
skol_info = TyConFlavour TyCon -> Name -> SkolemInfoAnon
TyConSkol TyConFlavour TyCon
flav Name
tc_name
    flav :: TyConFlavour TyCon
flav = NewOrData -> TyConFlavour TyCon
forall tc. NewOrData -> TyConFlavour tc
newOrDataToFlavour (DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn)) -> NewOrData
forall a. DataDefnCons a -> NewOrData
dataDefnConsNewOrData DataDefnCons (LConDecl GhcRn)
DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn))
cons)

    -- Abstract data types in hsig files can have arbitrary kinds,
    -- because they may be implemented by type synonyms
    -- (which themselves can have arbitrary kinds, not just *). See #13955.
    --
    -- Note that this is only a property that data type declarations possess,
    -- so one could not have, say, a data family instance in an hsig file that
    -- has kind `Bool`. Therefore, this check need only occur in the code that
    -- typechecks data type declarations.
    mk_permissive_kind :: HscSource -> DataDefnCons a -> Bool
mk_permissive_kind HscSource
HsigFile (DataTypeCons Bool
_ []) = Bool
True
    mk_permissive_kind HscSource
_ DataDefnCons a
_ = Bool
False

    -- In an hs-boot or a signature file,
    -- a 'data' declaration with no constructors
    -- indicates a nominally distinct abstract data type.
    mk_tc_rhs :: HscSource
-> TyCon
-> DataDefnCons DataCon
-> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
mk_tc_rhs (HscSource -> Bool
isHsBootOrSig -> Bool
True) TyCon
_ (DataTypeCons Bool
_ [])
      = AlgTyConRhs -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return AlgTyConRhs
AbstractTyCon

    mk_tc_rhs HscSource
_ TyCon
tycon DataDefnCons DataCon
data_cons = case DataDefnCons DataCon
data_cons of
          DataTypeCons Bool
is_type_data [DataCon]
data_cons -> AlgTyConRhs -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return (AlgTyConRhs -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs)
-> AlgTyConRhs -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall a b. (a -> b) -> a -> b
$
                        Bool -> Bool -> [DataCon] -> AlgTyConRhs
mkLevPolyDataTyConRhs
                          (HasDebugCallStack => Type -> Bool
Type -> Bool
isFixedRuntimeRepKind (TyCon -> Type
tyConResKind TyCon
tycon))
                          Bool
is_type_data
                          [DataCon]
data_cons
          NewTypeCon DataCon
data_con -> Name
-> TyCon -> DataCon -> IOEnv (Env TcGblEnv TcLclEnv) AlgTyConRhs
forall m n. Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs
mkNewTyConRhs Name
tc_name TyCon
tycon DataCon
data_con

-------------------------
kcTyFamInstEqn :: TcTyCon -> LTyFamInstEqn GhcRn -> TcM ()
-- Used for the equations of a closed type family only
-- Not used for data/type instances
kcTyFamInstEqn :: TyCon -> LTyFamInstEqn GhcRn -> TcRn ()
kcTyFamInstEqn TyCon
tc_fam_tc
    (L SrcSpanAnnA
loc (FamEqn { feqn_tycon :: forall pass rhs. FamEqn pass rhs -> LIdP pass
feqn_tycon = L SrcSpanAnnN
_ Name
eqn_tc_name
                   , feqn_bndrs :: forall pass rhs. FamEqn pass rhs -> HsOuterFamEqnTyVarBndrs pass
feqn_bndrs = HsOuterFamEqnTyVarBndrs GhcRn
outer_bndrs
                   , feqn_pats :: forall pass rhs. FamEqn pass rhs -> HsFamEqnPats pass
feqn_pats  = HsFamEqnPats GhcRn
hs_pats
                   , feqn_rhs :: forall pass rhs. FamEqn pass rhs -> rhs
feqn_rhs   = GenLocated SrcSpanAnnA (HsType GhcRn)
hs_rhs_ty }))
  = SrcSpanAnnA -> TcRn () -> TcRn ()
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"kcTyFamInstEqn" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
           [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"tc_name ="    SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
eqn_tc_name
           , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"fam_tc ="     SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc_fam_tc SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Type
tyConKind TyCon
tc_fam_tc)
           , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"feqn_bndrs =" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> HsOuterFamEqnTyVarBndrs GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsOuterFamEqnTyVarBndrs GhcRn
outer_bndrs
           , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"feqn_pats ="  SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> SDoc
forall a. Outputable a => a -> SDoc
ppr HsFamEqnPats GhcRn
[HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_pats ])

       ; TyCon
-> Name
-> [HsArg
      GhcRn
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> TcRn ()
forall p tm ty. TyCon -> Name -> [HsArg p tm ty] -> TcRn ()
checkTyFamInstEqn TyCon
tc_fam_tc Name
eqn_tc_name HsFamEqnPats GhcRn
[HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_pats

       ; TcM (HsOuterFamEqnTyVarBndrs GhcTc, Type) -> TcRn ()
forall a. TcM a -> TcRn ()
discardResult (TcM (HsOuterFamEqnTyVarBndrs GhcTc, Type) -> TcRn ())
-> TcM (HsOuterFamEqnTyVarBndrs GhcTc, Type) -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         HsOuterFamEqnTyVarBndrs GhcRn
-> IOEnv (Env TcGblEnv TcLclEnv) Type
-> TcM (HsOuterFamEqnTyVarBndrs GhcTc, Type)
forall a.
HsOuterFamEqnTyVarBndrs GhcRn
-> TcM a -> TcM (HsOuterFamEqnTyVarBndrs GhcTc, a)
bindOuterFamEqnTKBndrs_Q_Tv HsOuterFamEqnTyVarBndrs GhcRn
outer_bndrs (IOEnv (Env TcGblEnv TcLclEnv) Type
 -> TcM (HsOuterFamEqnTyVarBndrs GhcTc, Type))
-> IOEnv (Env TcGblEnv TcLclEnv) Type
-> TcM (HsOuterFamEqnTyVarBndrs GhcTc, Type)
forall a b. (a -> b) -> a -> b
$
         do { (_fam_app, res_kind) <- TyCon -> HsFamEqnPats GhcRn -> TcM (Type, Type)
tcFamTyPats TyCon
tc_fam_tc HsFamEqnPats GhcRn
hs_pats
            ; tcCheckLHsType hs_rhs_ty (TheKind res_kind) }
             -- Why "_Tv" here?  Consider (#14066)
             --  type family Bar x y where
             --      Bar (x :: a) (y :: b) = Int
             --      Bar (x :: c) (y :: d) = Bool
             -- During kind-checking, a,b,c,d should be TyVarTvs and unify appropriately
    }

--------------------------
tcTyFamInstEqn :: TcTyCon -> AssocInstInfo -> LTyFamInstEqn GhcRn
               -> TcM (KnotTied CoAxBranch, TyFamEqnValidityInfo)
-- Needs to be here, not in GHC.Tc.TyCl.Instance, because closed families
-- (typechecked here) have TyFamInstEqns

tcTyFamInstEqn :: TyCon
-> AssocInstInfo
-> LTyFamInstEqn GhcRn
-> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo)
tcTyFamInstEqn TyCon
fam_tc AssocInstInfo
mb_clsinfo
    (L SrcSpanAnnA
loc (FamEqn { feqn_tycon :: forall pass rhs. FamEqn pass rhs -> LIdP pass
feqn_tycon  = L SrcSpanAnnN
_ Name
eqn_tc_name
                   , feqn_bndrs :: forall pass rhs. FamEqn pass rhs -> HsOuterFamEqnTyVarBndrs pass
feqn_bndrs  = HsOuterFamEqnTyVarBndrs GhcRn
outer_bndrs
                   , feqn_pats :: forall pass rhs. FamEqn pass rhs -> HsFamEqnPats pass
feqn_pats   = HsFamEqnPats GhcRn
hs_pats
                   , feqn_rhs :: forall pass rhs. FamEqn pass rhs -> rhs
feqn_rhs    = GenLocated SrcSpanAnnA (HsType GhcRn)
hs_rhs_ty }))
  = SrcSpanAnnA
-> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo)
-> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo)
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo)
 -> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo))
-> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo)
-> TcRn (KnotTied CoAxBranch, TyFamEqnValidityInfo)
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"tcTyFamInstEqn" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ SrcSpanAnnA -> SDoc
forall a. Outputable a => a -> SDoc
ppr SrcSpanAnnA
loc, TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> SDoc
forall a. Outputable a => a -> SDoc
ppr HsFamEqnPats GhcRn
[HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_pats
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"fam tc bndrs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Var] -> SDoc
pprTyVars (TyCon -> [Var]
tyConTyVars TyCon
fam_tc)
              , case AssocInstInfo
mb_clsinfo of
                  NotAssociated {} -> SDoc
forall doc. IsOutput doc => doc
empty
                  InClsInst { ai_class :: AssocInstInfo -> Class
ai_class = Class
cls } -> String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"class" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr Class
cls SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Var] -> SDoc
pprTyVars (Class -> [Var]
classTyVars Class
cls) ]

       ; TyCon
-> Name
-> [HsArg
      GhcRn
      (GenLocated SrcSpanAnnA (HsType GhcRn))
      (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> TcRn ()
forall p tm ty. TyCon -> Name -> [HsArg p tm ty] -> TcRn ()
checkTyFamInstEqn TyCon
fam_tc Name
eqn_tc_name HsFamEqnPats GhcRn
[HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_pats

       ; (qtvs, non_user_tvs, pats, rhs_ty)
           <- TyCon
-> AssocInstInfo
-> HsOuterFamEqnTyVarBndrs GhcRn
-> HsFamEqnPats GhcRn
-> LHsKind GhcRn
-> TcM ([Var], VarSet, ThetaType, Type)
tcTyFamInstEqnGuts TyCon
fam_tc AssocInstInfo
mb_clsinfo
                HsOuterFamEqnTyVarBndrs GhcRn
outer_bndrs HsFamEqnPats GhcRn
hs_pats LHsKind GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
hs_rhs_ty
       -- Don't print results they may be knot-tied
       -- (tcFamInstEqnGuts zonks to Type)

       ; let ax = [Var]
-> [Var]
-> [Var]
-> ThetaType
-> Type
-> [Role]
-> SrcSpan
-> KnotTied CoAxBranch
mkCoAxBranch [Var]
qtvs [] [] ThetaType
pats Type
rhs_ty
                    ((Var -> Role) -> [Var] -> [Role]
forall a b. (a -> b) -> [a] -> [b]
map (Role -> Var -> Role
forall a b. a -> b -> a
const Role
Nominal) [Var]
qtvs)
                    (SrcSpanAnnA -> SrcSpan
forall a. HasLoc a => a -> SrcSpan
locA SrcSpanAnnA
loc)
             vi = VI { vi_loc :: SrcSpan
vi_loc          = SrcSpanAnnA -> SrcSpan
forall a. HasLoc a => a -> SrcSpan
locA SrcSpanAnnA
loc
                     , vi_qtvs :: [Var]
vi_qtvs         = [Var]
qtvs
                     , vi_non_user_tvs :: VarSet
vi_non_user_tvs = VarSet
non_user_tvs
                     , vi_pats :: ThetaType
vi_pats         = ThetaType
pats
                     , vi_rhs :: Type
vi_rhs          = Type
rhs_ty }

       ; return (ax, vi) }

checkTyFamInstEqn :: TcTyCon -> Name -> [HsArg p tm ty] -> TcM ()
checkTyFamInstEqn :: forall p tm ty. TyCon -> Name -> [HsArg p tm ty] -> TcRn ()
checkTyFamInstEqn TyCon
tc_fam_tc Name
eqn_tc_name [HsArg p tm ty]
hs_pats =
  do { -- Ensure that each equation's type constructor is for the right
       -- type family.  E.g. barf on
       --    type family F a where { G Int = Bool }
       let tc_fam_tc_name :: Name
tc_fam_tc_name = TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
tc_fam_tc
     ; Bool -> TcRnMessage -> TcRn ()
checkTc (Name
tc_fam_tc_name Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
eqn_tc_name) (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
               IllegalInstanceReason -> TcRnMessage
TcRnIllegalInstance (IllegalInstanceReason -> TcRnMessage)
-> IllegalInstanceReason -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ IllegalFamilyInstanceReason -> IllegalInstanceReason
IllegalFamilyInstance (IllegalFamilyInstanceReason -> IllegalInstanceReason)
-> IllegalFamilyInstanceReason -> IllegalInstanceReason
forall a b. (a -> b) -> a -> b
$
               Name -> Name -> IllegalFamilyInstanceReason
TyFamNameMismatch Name
tc_fam_tc_name Name
eqn_tc_name

       -- Check the arity of visible arguments
       -- If we wait until validity checking, we'll get kind errors
       -- below when an arity error will be much easier to understand.
     ; let vis_arity :: Int
vis_arity = [Var] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (TyCon -> [Var]
tyConVisibleTyVars TyCon
tc_fam_tc)
           vis_pats :: Int
vis_pats  = [HsArg p tm ty] -> Int
forall p tm ty. [HsArg p tm ty] -> Int
numVisibleArgs [HsArg p tm ty]
hs_pats
     ; Bool -> TcRnMessage -> TcRn ()
checkTc (Int
vis_pats Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
vis_arity) (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        IllegalInstanceReason -> TcRnMessage
TcRnIllegalInstance (IllegalInstanceReason -> TcRnMessage)
-> IllegalInstanceReason -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ IllegalFamilyInstanceReason -> IllegalInstanceReason
IllegalFamilyInstance (IllegalFamilyInstanceReason -> IllegalInstanceReason)
-> IllegalFamilyInstanceReason -> IllegalInstanceReason
forall a b. (a -> b) -> a -> b
$
        TyCon -> Int -> IllegalFamilyInstanceReason
FamilyArityMismatch TyCon
tc_fam_tc Int
vis_arity
     }

{- Note [Instantiating a family tycon]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's possible that kind-checking the result of a family tycon applied to
its patterns will instantiate the tycon further. For example, we might
have

  type family F :: k where
    F = Int
    F = Maybe

After checking (F :: forall k. k) (with no visible patterns), we still need
to instantiate the k. With data family instances, this problem can be even
more intricate, due to Note [Arity of data families] in GHC.Core.FamInstEnv. See
indexed-types/should_compile/T12369 for an example.

So, the kind-checker must return the new skolems and args (that is, Type
or (Type -> Type) for the equations above) and the instantiated kind.

Note [Generalising in tcTyFamInstEqnGuts]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose we have something like
  type instance forall (a::k) b. F (Proxy t1) _ = rhs

Then  imp_vars = [k], exp_bndrs = [a::k, b]

We want to quantify over all the free vars of the LHS including
  * any invisible kind variables arising from instantiating tycons,
    such as Proxy
  * wildcards such as '_' above

The wildcards are particularly awkward: they may need to be quantified
  - before the explicit variables k,a,b
  - after them
  - or even interleaved with them
  c.f. Note [Naughty quantification candidates] in GHC.Tc.Utils.TcMType

So, we use bindOuterFamEqnTKBndrs (which does not create an implication for
the telescope), and generalise over /all/ the variables in the LHS,
without treating the explicitly-quantified ones specially. Wrinkles:

 - When generalising, include the explicit user-specified forall'd
   variables, so that we get an error from Validity.checkFamPatBinders
   if a forall'd variable is not bound on the LHS

 - We still want to complain about a bad telescope among the user-specified
   variables.  So in checkFamTelescope we emit an implication constraint
   quantifying only over them, purely so that we get a good telescope error.

  - Note that, unlike a type signature like
       f :: forall (a::k). blah
    we do /not/ care about the Inferred/Specified designation or order for
    the final quantified tyvars.  Type-family instances are not invoked
    directly in Haskell source code, so visible type application etc plays
    no role.

See also Note [Re-quantify type variables in rules] in
GHC.Tc.Gen.Rule, which explains a /very/ similar design when
generalising over the type of a rewrite rule.

-}

--------------------------

tcTyFamInstEqnGuts :: TyCon -> AssocInstInfo
                   -> HsOuterFamEqnTyVarBndrs GhcRn     -- Implicit and explicit binders
                   -> HsFamEqnPats GhcRn                -- Patterns
                   -> LHsType GhcRn                     -- RHS
                   -> TcM ([TyVar], TyVarSet, [TcType], TcType)
                       -- (tyvars, non_user_tvs, pats, rhs)
-- Used only for type families, not data families
tcTyFamInstEqnGuts :: TyCon
-> AssocInstInfo
-> HsOuterFamEqnTyVarBndrs GhcRn
-> HsFamEqnPats GhcRn
-> LHsKind GhcRn
-> TcM ([Var], VarSet, ThetaType, Type)
tcTyFamInstEqnGuts TyCon
fam_tc AssocInstInfo
mb_clsinfo HsOuterFamEqnTyVarBndrs GhcRn
outer_hs_bndrs HsFamEqnPats GhcRn
hs_pats LHsKind GhcRn
hs_rhs_ty
  = do { String -> SDoc -> TcRn ()
traceTc String
"tcTyFamInstEqnGuts {" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ HsOuterFamEqnTyVarBndrs GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsOuterFamEqnTyVarBndrs GhcRn
outer_hs_bndrs SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> SDoc
forall a. Outputable a => a -> SDoc
ppr HsFamEqnPats GhcRn
[HsArg
   GhcRn
   (GenLocated SrcSpanAnnA (HsType GhcRn))
   (GenLocated SrcSpanAnnA (HsType GhcRn))]
hs_pats)

       -- By now, for type families (but not data families) we should
       -- have checked that the number of patterns matches tyConArity
       ; skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo SkolemInfoAnon
FamInstSkol

       -- This code is closely related to the code
       -- in GHC.Tc.Gen.HsType.kcCheckDeclHeader_cusk
       ; (tclvl, wanted, (outer_bndrs, (lhs_ty, rhs_ty)))
               <- pushLevelAndSolveEqualitiesX "tcTyFamInstEqnGuts" $
                  bindOuterFamEqnTKBndrs skol_info outer_hs_bndrs   $
                  do { (lhs_ty, rhs_kind) <- tcFamTyPats fam_tc hs_pats
                       -- Ensure that the instance is consistent with its
                       -- parent class (#16008)
                     ; addConsistencyConstraints mb_clsinfo lhs_ty
                     ; rhs_ty <- tcCheckLHsType hs_rhs_ty (TheKind rhs_kind)
                     ; return (lhs_ty, rhs_ty) }

       ; outer_bndrs <- scopedSortOuter outer_bndrs
       ; let outer_tvs = HsOuterFamEqnTyVarBndrs GhcTc -> [Var]
forall flag. HsOuterTyVarBndrs flag GhcTc -> [Var]
outerTyVars HsOuterFamEqnTyVarBndrs GhcTc
outer_bndrs
       ; checkFamTelescope tclvl outer_hs_bndrs outer_tvs

       ; traceTc "tcTyFamInstEqnGuts 1" (pprTyVars outer_tvs $$ ppr skol_info)

       -- This code (and the stuff immediately above) is very similar
       -- to that in tcDataFamInstHeader.  Maybe we should abstract the
       -- common code; but for the moment I concluded that it's
       -- clearer to duplicate it.  Still, if you fix a bug here,
       -- check there too!

       -- See Note [Generalising in tcTyFamInstEqnGuts]
       ; dvs  <- candidateQTyVarsWithBinders outer_tvs lhs_ty
       ; qtvs <- quantifyTyVars skol_info TryNotToDefaultNonStandardTyVars dvs
       ; let final_tvs = [Var] -> [Var]
scopedSort ([Var]
qtvs [Var] -> [Var] -> [Var]
forall a. [a] -> [a] -> [a]
++ [Var]
outer_tvs)
             -- This scopedSort is important: the qtvs may be /interleaved/ with
             -- the outer_tvs.  See Note [Generalising in tcTyFamInstEqnGuts]
       ; reportUnsolvedEqualities skol_info final_tvs tclvl wanted

       ; traceTc "tcTyFamInstEqnGuts 2" $
         vcat [ ppr fam_tc
              , text "lhs_ty:"    <+> ppr lhs_ty
              , text "final_tvs:" <+> pprTyVars final_tvs ]

       -- See Note [Error on unconstrained meta-variables] in GHC.Tc.Utils.TcMType
       -- Example: typecheck/should_fail/T17301
       ; dvs_rhs <- candidateQTyVarsOfType rhs_ty
       ; let err_ctx TidyEnv
tidy_env
               = do { (tidy_env2, rhs_ty) <- TidyEnv -> Type -> ZonkM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env Type
rhs_ty
                    ; return (tidy_env2, UninfTyCtx_TyFamRhs rhs_ty) }
       ; doNotQuantifyTyVars dvs_rhs err_ctx

       ; (final_tvs, non_user_tvs, lhs_ty, rhs_ty) <- initZonkEnv NoFlexi $
         runZonkBndrT (zonkTyBndrsX final_tvs) $ \ [Var]
final_tvs ->
           do { lhs_ty       <- Type -> ZonkTcM Type
zonkTcTypeToTypeX Type
lhs_ty
              ; rhs_ty       <- zonkTcTypeToTypeX rhs_ty
              ; non_user_tvs <- traverse lookupTyVarX qtvs
              ; return (final_tvs, non_user_tvs, lhs_ty, rhs_ty) }

       ; let pats = Type -> ThetaType
unravelFamInstPats Type
lhs_ty
             -- Note that we do this after solveEqualities
             -- so that any strange coercions inside lhs_ty
             -- have been solved before we attempt to unravel it

       ; traceTc "tcTyFamInstEqnGuts }" (vcat [ ppr fam_tc, pprTyVars final_tvs ])
                 -- Don't try to print 'pats' here, because lhs_ty involves
                 -- a knot-tied type constructor, so we get a black hole

       ; return (final_tvs, mkVarSet non_user_tvs, pats, rhs_ty) }

checkFamTelescope :: TcLevel
                  -> HsOuterFamEqnTyVarBndrs GhcRn
                  -> [TcTyVar] -> TcM ()
-- Emit a constraint (forall a b c. <empty>), so that
-- we will do telescope-checking on a,b,c
-- See Note [Generalising in tcTyFamInstEqnGuts]
checkFamTelescope :: TcLevel -> HsOuterFamEqnTyVarBndrs GhcRn -> [Var] -> TcRn ()
checkFamTelescope TcLevel
tclvl HsOuterFamEqnTyVarBndrs GhcRn
hs_outer_bndrs [Var]
outer_tvs
  | HsOuterExplicit { hso_bndrs :: forall flag pass.
HsOuterTyVarBndrs flag pass -> [LHsTyVarBndr flag (NoGhcTc pass)]
hso_bndrs = [LHsTyVarBndr () (NoGhcTc GhcRn)]
bndrs } <- HsOuterFamEqnTyVarBndrs GhcRn
hs_outer_bndrs
  , (LHsTyVarBndr () (NoGhcTc GhcRn)
b_first : [LHsTyVarBndr () (NoGhcTc GhcRn)]
_) <- [LHsTyVarBndr () (NoGhcTc GhcRn)]
bndrs
  , let b_last :: GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)
b_last    = [GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
-> GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)
forall a. HasCallStack => [a] -> a
last [LHsTyVarBndr () (NoGhcTc GhcRn)]
[GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
bndrs
  = do { skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo (TyVarBndrs -> SkolemInfoAnon
ForAllSkol (TyVarBndrs -> SkolemInfoAnon) -> TyVarBndrs -> SkolemInfoAnon
forall a b. (a -> b) -> a -> b
$ [HsTyVarBndr () GhcRn] -> TyVarBndrs
forall flag.
OutputableBndrFlag flag 'Renamed =>
[HsTyVarBndr flag GhcRn] -> TyVarBndrs
HsTyVarBndrsRn ((GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)
 -> HsTyVarBndr () GhcRn)
-> [GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
-> [HsTyVarBndr () GhcRn]
forall a b. (a -> b) -> [a] -> [b]
map GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)
-> HsTyVarBndr () GhcRn
forall l e. GenLocated l e -> e
unLoc [LHsTyVarBndr () (NoGhcTc GhcRn)]
[GenLocated SrcSpanAnnA (HsTyVarBndr () GhcRn)]
bndrs))
       ; setSrcSpan (combineSrcSpans (getLocA b_first) (getLocA b_last)) $ do
         emitResidualTvConstraint skol_info outer_tvs tclvl emptyWC }
  | Bool
otherwise
  = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

-----------------
unravelFamInstPats :: TcType -> [TcType]
-- Decompose fam_app to get the argument patterns
--
-- We expect fam_app to look like (F t1 .. tn)
--   tcFamTyPats is capable of returning ((F ty1 |> co) ty2),
--   but that can't happen here because we already checked the
--   arity of F matches the number of pattern
unravelFamInstPats :: Type -> ThetaType
unravelFamInstPats Type
fam_app
  = case HasCallStack => Type -> Maybe (TyCon, ThetaType)
Type -> Maybe (TyCon, ThetaType)
tcSplitTyConApp_maybe Type
fam_app of
      Just (TyCon
_, ThetaType
pats) -> ThetaType
pats
      Maybe (TyCon, ThetaType)
Nothing -> String -> ThetaType
forall a. HasCallStack => String -> a
panic String
"unravelFamInstPats: Ill-typed LHS of family instance"
        -- The Nothing case cannot happen for type families, because
        -- we don't call unravelFamInstPats until we've solved the
        -- equalities. For data families, it shouldn't happen either,
        -- we need to fail hard and early if it does. See issue #15905
        -- for an example of this happening.

addConsistencyConstraints :: AssocInstInfo -> TcType -> TcM ()
-- In the corresponding positions of the class and type-family,
-- ensure the family argument is the same as the class argument
--   E.g    class C a b c d where
--             F c x y a :: Type
-- Here the first  arg of F should be the same as the third of C
--  and the fourth arg of F should be the same as the first of C
addConsistencyConstraints :: AssocInstInfo -> Type -> TcRn ()
addConsistencyConstraints AssocInstInfo
mb_clsinfo Type
fam_app
  | InClsInst { ai_inst_env :: AssocInstInfo -> VarEnv Type
ai_inst_env = VarEnv Type
inst_env } <- AssocInstInfo
mb_clsinfo
  , Just (TyCon
fam_tc, ThetaType
pats) <- HasCallStack => Type -> Maybe (TyCon, ThetaType)
Type -> Maybe (TyCon, ThetaType)
tcSplitTyConApp_maybe Type
fam_app
  = do { let eqs :: [(Type, Type)]
eqs = [ (Type
cls_ty, Type
pat)
                   | (Var
fam_tc_tv, Type
pat) <- TyCon -> [Var]
tyConTyVars TyCon
fam_tc [Var] -> ThetaType -> [(Var, Type)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` ThetaType
pats
                   , Just Type
cls_ty <- [VarEnv Type -> Var -> Maybe Type
forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv VarEnv Type
inst_env Var
fam_tc_tv] ]
       ; String -> SDoc -> TcRn ()
traceTc String
"addConsistencyConstraints" ([(Type, Type)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(Type, Type)]
eqs)
       ; CtOrigin -> [(Type, Type)] -> TcRn ()
emitWantedEqs CtOrigin
AssocFamPatOrigin [(Type, Type)]
eqs }
    -- Improve inference; these equalities will not produce errors.
    -- See Note [Constraints to ignore] in GHC.Tc.Errors
    -- Any mis-match is reports by checkConsistentFamInst
  | Bool
otherwise
  = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

{- Note [Constraints in patterns]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NB: This isn't the whole story. See comment in tcFamTyPats.

At first glance, it seems there is a complicated story to tell in tcFamTyPats
around constraint solving. After all, type family patterns can now do
GADT pattern-matching, which is jolly complicated. But, there's a key fact
which makes this all simple: everything is at top level! There cannot
be untouchable type variables. There can't be weird interaction between
case branches. There can't be global skolems.

This means that the semantics of type-level GADT matching is a little
different than term level. If we have

  data G a where
    MkGBool :: G Bool

And then

  type family F (a :: G k) :: k
  type instance F MkGBool = True

we get

  axF : F Bool (MkGBool <Bool>) ~ True

Simple! No casting on the RHS, because we can affect the kind parameter
to F.

If we ever introduce local type families, this all gets a lot more
complicated, and will end up looking awfully like term-level GADT
pattern-matching.


** The new story **

Here is really what we want:

The matcher really can't deal with covars in arbitrary spots in coercions.
But it can deal with covars that are arguments to GADT data constructors.
So we somehow want to allow covars only in precisely those spots, then use
them as givens when checking the RHS. TODO (RAE): Implement plan.

Note [Quantified kind variables of a family pattern]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider   type family KindFam (p :: k1) (q :: k1)
           data T :: Maybe k1 -> k2 -> *
           type instance KindFam (a :: Maybe k) b = T a b -> Int
The HsBSig for the family patterns will be ([k], [a])

Then in the family instance we want to
  * Bring into scope [ "k" -> k:*, "a" -> a:k ]
  * Kind-check the RHS
  * Quantify the type instance over k and k', as well as a,b, thus
       type instance [k, k', a:Maybe k, b:k']
                     KindFam (Maybe k) k' a b = T k k' a b -> Int

Notice that in the third step we quantify over all the visibly-mentioned
type variables (a,b), but also over the implicitly mentioned kind variables
(k, k').  In this case one is bound explicitly but often there will be
none. The role of the kind signature (a :: Maybe k) is to add a constraint
that 'a' must have that kind, and to bring 'k' into scope.



************************************************************************
*                                                                      *
               Data types
*                                                                      *
************************************************************************
-}

dataDeclChecks :: Name
               -> Maybe (LHsContext GhcRn) -> DataDefnCons (LConDecl GhcRn)
               -> TcM Bool
dataDeclChecks :: Name
-> Maybe (LHsContext GhcRn)
-> DataDefnCons (LConDecl GhcRn)
-> TcRnIf TcGblEnv TcLclEnv Bool
dataDeclChecks Name
tc_name Maybe (LHsContext GhcRn)
mctxt DataDefnCons (LConDecl GhcRn)
cons
  = do { let stupid_theta :: HsContext GhcRn
stupid_theta = Maybe (LHsContext GhcRn) -> HsContext GhcRn
forall (p :: Pass).
Maybe (LHsContext (GhcPass p)) -> HsContext (GhcPass p)
fromMaybeContext Maybe (LHsContext GhcRn)
mctxt
         -- Check that we don't use GADT syntax in H98 world
       ;  gadtSyntax_ok <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.GADTSyntax
       ; let gadt_syntax = DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn)) -> Bool
forall (f :: * -> *) l pass.
Foldable f =>
f (GenLocated l (ConDecl pass)) -> Bool
anyLConIsGadt DataDefnCons (LConDecl GhcRn)
DataDefnCons (GenLocated SrcSpanAnnA (ConDecl GhcRn))
cons
       ; unless (gadtSyntax_ok || not gadt_syntax) $
         addErrTc (TcRnGADTsDisabled tc_name)

           -- Check that the stupid theta is empty for a GADT-style declaration.
           -- See Note [The stupid context] in GHC.Core.DataCon.
       ; checkTc (null stupid_theta || not gadt_syntax) (TcRnGADTDataContext tc_name)

         -- Check that there's at least one condecl,
         -- or else we're reading an hs-boot file, or -XEmptyDataDecls
       ; empty_data_decls <- xoptM LangExt.EmptyDataDecls
       ; is_boot <- tcIsHsBootOrSig  -- Are we compiling an hs-boot file?
       ; unless (not (null cons) || empty_data_decls || is_boot) $
                 addErrTc (TcRnEmptyDataDeclsDisabled tc_name)
       ; return gadt_syntax }


-----------------------------------
data DataDeclInfo
  = DDataType      -- data T a b = T1 a | T2 b
  | DDataInstance  -- data instance D [a] = D1 a | D2
       Type        --   The header D [a]

mkDDHeaderTy :: DataDeclInfo -> TyCon -> [TyConBinder] -> Type
mkDDHeaderTy :: DataDeclInfo -> TyCon -> [TyConBinder] -> Type
mkDDHeaderTy DataDeclInfo
dd_info TyCon
rep_tycon [TyConBinder]
tc_bndrs
  = case DataDeclInfo
dd_info of
      DataDeclInfo
DDataType -> TyCon -> ThetaType -> Type
mkTyConApp TyCon
rep_tycon (ThetaType -> Type) -> ThetaType -> Type
forall a b. (a -> b) -> a -> b
$
                   [Var] -> ThetaType
mkTyVarTys ([TyConBinder] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tc_bndrs)
      DDataInstance Type
header_ty -> Type
header_ty

-- We use `concatMapDataDefnConsTcM` here, since the following is illegal:
-- @newtype T a where T1, T2 :: a -> T a@
-- It would be represented as a single 'ConDeclGadt' with multiple names, which is valid for 'data', but not 'newtype'.
-- So when 'tcConDecl' expands the 'ConDecl' per each name it has, if we are type-checking a 'newtype' declaration, we
-- must fail if it returns more than one.
tcConDecls :: DataDeclInfo
           -> KnotTied TyCon            -- Representation TyCon
           -> [TcTyConBinder]           -- Binders of representation TyCon
           -> TcKind                    -- Result kind
           -> DataDefnCons (LConDecl GhcRn) -> TcM (DataDefnCons DataCon)
tcConDecls :: DataDeclInfo
-> TyCon
-> [TyConBinder]
-> Type
-> DataDefnCons (LConDecl GhcRn)
-> TcM (DataDefnCons DataCon)
tcConDecls DataDeclInfo
dd_info TyCon
rep_tycon [TyConBinder]
tmpl_bndrs Type
res_kind
  = Name
-> (NewOrData -> LConDecl GhcRn -> TcM (NonEmpty DataCon))
-> DataDefnCons (LConDecl GhcRn)
-> TcM (DataDefnCons DataCon)
forall a b.
Name
-> (NewOrData -> a -> TcM (NonEmpty b))
-> DataDefnCons a
-> TcM (DataDefnCons b)
concatMapDataDefnConsTcM (TyCon -> Name
tyConName TyCon
rep_tycon) ((NewOrData -> LConDecl GhcRn -> TcM (NonEmpty DataCon))
 -> DataDefnCons (LConDecl GhcRn) -> TcM (DataDefnCons DataCon))
-> (NewOrData -> LConDecl GhcRn -> TcM (NonEmpty DataCon))
-> DataDefnCons (LConDecl GhcRn)
-> TcM (DataDefnCons DataCon)
forall a b. (a -> b) -> a -> b
$ \ NewOrData
new_or_data ->
    (ConDecl GhcRn -> TcM (NonEmpty DataCon))
-> GenLocated SrcSpanAnnA (ConDecl GhcRn) -> TcM (NonEmpty DataCon)
forall t a b. HasLoc t => (a -> TcM b) -> GenLocated t a -> TcM b
addLocM ((ConDecl GhcRn -> TcM (NonEmpty DataCon))
 -> GenLocated SrcSpanAnnA (ConDecl GhcRn)
 -> TcM (NonEmpty DataCon))
-> (ConDecl GhcRn -> TcM (NonEmpty DataCon))
-> GenLocated SrcSpanAnnA (ConDecl GhcRn)
-> TcM (NonEmpty DataCon)
forall a b. (a -> b) -> a -> b
$ NewOrData
-> DataDeclInfo
-> TyCon
-> [TyConBinder]
-> Type
-> NameEnv Int
-> ConDecl GhcRn
-> TcM (NonEmpty DataCon)
tcConDecl NewOrData
new_or_data DataDeclInfo
dd_info TyCon
rep_tycon [TyConBinder]
tmpl_bndrs Type
res_kind (TyCon -> NameEnv Int
mkTyConTagMap TyCon
rep_tycon)
    -- mkTyConTagMap: it's important that we pay for tag allocation here,
    -- once per TyCon. See Note [Constructor tag allocation], fixes #14657

-- 'concatMap' for 'DataDefnCons', but fail if the given function returns multiple values and the argument is a 'NewTypeCon'.
concatMapDataDefnConsTcM :: Name -> (NewOrData -> a -> TcM (NonEmpty b)) -> DataDefnCons a -> TcM (DataDefnCons b)
concatMapDataDefnConsTcM :: forall a b.
Name
-> (NewOrData -> a -> TcM (NonEmpty b))
-> DataDefnCons a
-> TcM (DataDefnCons b)
concatMapDataDefnConsTcM Name
name NewOrData -> a -> TcM (NonEmpty b)
f = \ case
    NewTypeCon a
a -> NewOrData -> a -> TcM (NonEmpty b)
f NewOrData
NewType a
a TcM (NonEmpty b)
-> (NonEmpty b -> TcM (DataDefnCons b)) -> TcM (DataDefnCons b)
forall a b.
IOEnv (Env TcGblEnv TcLclEnv) a
-> (a -> IOEnv (Env TcGblEnv TcLclEnv) b)
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= \ case
        b
b:|[] -> DataDefnCons b -> TcM (DataDefnCons b)
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (b -> DataDefnCons b
forall a. a -> DataDefnCons a
NewTypeCon b
b)
        NonEmpty b
bs -> TcRnMessage -> TcM (DataDefnCons b)
forall a. TcRnMessage -> TcM a
failWithTc (TcRnMessage -> TcM (DataDefnCons b))
-> TcRnMessage -> TcM (DataDefnCons b)
forall a b. (a -> b) -> a -> b
$ Name -> Int -> TcRnMessage
TcRnMultipleConForNewtype Name
name (NonEmpty b -> Int
forall a. NonEmpty a -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length NonEmpty b
bs)
    DataTypeCons Bool
is_type_data [a]
as -> Bool -> [b] -> DataDefnCons b
forall a. Bool -> [a] -> DataDefnCons a
DataTypeCons Bool
is_type_data ([b] -> DataDefnCons b)
-> IOEnv (Env TcGblEnv TcLclEnv) [b] -> TcM (DataDefnCons b)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (a -> IOEnv (Env TcGblEnv TcLclEnv) [b])
-> [a] -> IOEnv (Env TcGblEnv TcLclEnv) [b]
forall (m :: * -> *) (f :: * -> *) a b.
(Monad m, Traversable f) =>
(a -> m [b]) -> f a -> m [b]
concatMapM ((NonEmpty b -> [b])
-> TcM (NonEmpty b) -> IOEnv (Env TcGblEnv TcLclEnv) [b]
forall a b.
(a -> b)
-> IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap NonEmpty b -> [b]
forall a. NonEmpty a -> [a]
forall (t :: * -> *) a. Foldable t => t a -> [a]
toList (TcM (NonEmpty b) -> IOEnv (Env TcGblEnv TcLclEnv) [b])
-> (a -> TcM (NonEmpty b))
-> a
-> IOEnv (Env TcGblEnv TcLclEnv) [b]
forall b c a. (b -> c) -> (a -> b) -> a -> c
. NewOrData -> a -> TcM (NonEmpty b)
f NewOrData
DataType) [a]
as

tcConDecl :: NewOrData
          -> DataDeclInfo
          -> KnotTied TyCon   -- Representation tycon. Knot-tied!
          -> [TcTyConBinder]  -- Binders of representation TyCon
          -> TcKind           -- Result kind
          -> NameEnv ConTag
          -> ConDecl GhcRn
          -> TcM (NonEmpty DataCon)

tcConDecl :: NewOrData
-> DataDeclInfo
-> TyCon
-> [TyConBinder]
-> Type
-> NameEnv Int
-> ConDecl GhcRn
-> TcM (NonEmpty DataCon)
tcConDecl NewOrData
new_or_data DataDeclInfo
dd_info TyCon
rep_tycon [TyConBinder]
tc_bndrs Type
res_kind NameEnv Int
tag_map
          (ConDeclH98 { con_name :: forall pass. ConDecl pass -> LIdP pass
con_name = lname :: LIdP GhcRn
lname@(L SrcSpanAnnN
_ Name
name)
                      , con_ex_tvs :: forall pass. ConDecl pass -> [LHsTyVarBndr Specificity pass]
con_ex_tvs = [LHsTyVarBndr Specificity GhcRn]
explicit_tkv_nms
                      , con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (LHsContext GhcRn)
hs_ctxt
                      , con_args :: forall pass. ConDecl pass -> HsConDeclH98Details pass
con_args = HsConDeclH98Details GhcRn
hs_args })
  = SDoc -> TcM (NonEmpty DataCon) -> TcM (NonEmpty DataCon)
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (NonEmpty (LocatedN Name) -> SDoc
dataConCtxt (LocatedN Name -> NonEmpty (LocatedN Name)
forall a. a -> NonEmpty a
NE.singleton LIdP GhcRn
LocatedN Name
lname)) (TcM (NonEmpty DataCon) -> TcM (NonEmpty DataCon))
-> TcM (NonEmpty DataCon) -> TcM (NonEmpty DataCon)
forall a b. (a -> b) -> a -> b
$
    do { -- NB: the tyvars from the declaration header are in scope

         -- Get hold of the existential type variables
         -- e.g. data T a = forall k (b::k) f. MkT a (f b)
         -- Here tc_bndrs = {a}
         --      hs_qvars = HsQTvs { hsq_implicit = {k}
         --                        , hsq_explicit = {f,b} }

       ; String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 1" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name
                                     , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"explicit_tkv_nms" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [GenLocated SrcSpanAnnA (HsTyVarBndr Specificity GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LHsTyVarBndr Specificity GhcRn]
[GenLocated SrcSpanAnnA (HsTyVarBndr Specificity GhcRn)]
explicit_tkv_nms
                                     , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"tc_bndrs" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyConBinder]
tc_bndrs ])
       ; skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo (TyVarBndrs -> SkolemInfoAnon
ForAllSkol ([HsTyVarBndr Specificity GhcRn] -> TyVarBndrs
forall flag.
OutputableBndrFlag flag 'Renamed =>
[HsTyVarBndr flag GhcRn] -> TyVarBndrs
HsTyVarBndrsRn (GenLocated SrcSpanAnnA (HsTyVarBndr Specificity GhcRn)
-> HsTyVarBndr Specificity GhcRn
forall l e. GenLocated l e -> e
unLoc (GenLocated SrcSpanAnnA (HsTyVarBndr Specificity GhcRn)
 -> HsTyVarBndr Specificity GhcRn)
-> [GenLocated SrcSpanAnnA (HsTyVarBndr Specificity GhcRn)]
-> [HsTyVarBndr Specificity GhcRn]
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> [LHsTyVarBndr Specificity GhcRn]
[GenLocated SrcSpanAnnA (HsTyVarBndr Specificity GhcRn)]
explicit_tkv_nms)))

       ; (tclvl, wanted, (exp_tvbndrs, (ctxt, arg_tys, field_lbls, stricts)))
           <- pushLevelAndSolveEqualitiesX "tcConDecl:H98"  $
              tcExplicitTKBndrs skol_info explicit_tkv_nms  $
              do { ctxt <- tcHsContext hs_ctxt
                 ; let exp_kind = NewOrData -> Type -> ContextKind
getArgExpKind NewOrData
new_or_data Type
res_kind
                 ; btys <- tcConH98Args exp_kind hs_args
                 ; field_lbls <- lookupConstructorFields name
                 ; let (arg_tys, stricts) = unzip btys
                 ; return (ctxt, arg_tys, field_lbls, stricts)
                 }


       ; let tc_tvs   = [TyConBinder] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tc_bndrs
             fake_ty  = [Var] -> Type -> Type
mkSpecForAllTys  [Var]
tc_tvs      (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$
                        [VarBndr Var Specificity] -> Type -> Type
mkInvisForAllTys [VarBndr Var Specificity]
exp_tvbndrs (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$
                        ThetaType -> Type -> Type
HasDebugCallStack => ThetaType -> Type -> Type
tcMkPhiTy ThetaType
ctxt               (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$
                        [Scaled Type] -> Type -> Type
tcMkScaledFunTys [Scaled Type]
arg_tys     (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$
                        Type
unitTy
             -- That type is a lie, of course. (It shouldn't end in ()!)
             -- And we could construct a proper result type from the info
             -- at hand. But the result would mention only the univ_tvs,
             -- and so it just creates more work to do it right. Really,
             -- we're only doing this to find the right kind variables to
             -- quantify over, and this type is fine for that purpose.

         -- exp_tvbndrs have explicit, user-written binding sites
         -- the kvs below are those kind variables entirely unmentioned by the user
         --   and discovered only by generalization

       ; kvs <- kindGeneralizeAll skol_info fake_ty

       ; let all_skol_tvs = [Var]
tc_tvs [Var] -> [Var] -> [Var]
forall a. [a] -> [a] -> [a]
++ [Var]
kvs
       ; reportUnsolvedEqualities skol_info all_skol_tvs tclvl wanted
             -- The skol_info claims that all the variables are bound
             -- by the data constructor decl, whereas actually the
             -- univ_tvs are bound by the data type decl itself.  It
             -- would be better to have a doubly-nested implication.
             -- But that just doesn't seem worth it.
             -- See test dependent/should_fail/T13780a

       -- Zonk to Types
       ; (tc_bndrs, kvs, exp_tvbndrs, arg_tys, ctxt) <- initZonkEnv NoFlexi $
         runZonkBndrT (zonkTyVarBindersX tc_bndrs   ) $ \ [TyConBinder]
tc_bndrs ->
         ZonkBndrT (IOEnv (Env TcGblEnv TcLclEnv)) [Var]
-> forall r.
   ([Var] -> ZonkT (IOEnv (Env TcGblEnv TcLclEnv)) r)
   -> ZonkT (IOEnv (Env TcGblEnv TcLclEnv)) r
forall (m :: * -> *) a.
ZonkBndrT m a -> forall r. (a -> ZonkT m r) -> ZonkT m r
runZonkBndrT ([Var] -> ZonkBndrT (IOEnv (Env TcGblEnv TcLclEnv)) [Var]
zonkTyBndrsX      [Var]
kvs        ) (([Var]
  -> ZonkT
       (IOEnv (Env TcGblEnv TcLclEnv))
       ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
        ThetaType))
 -> ZonkT
      (IOEnv (Env TcGblEnv TcLclEnv))
      ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
       ThetaType))
-> ([Var]
    -> ZonkT
         (IOEnv (Env TcGblEnv TcLclEnv))
         ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
          ThetaType))
-> ZonkT
     (IOEnv (Env TcGblEnv TcLclEnv))
     ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
      ThetaType)
forall a b. (a -> b) -> a -> b
$ \ [Var]
kvs ->
         ZonkBndrT (IOEnv (Env TcGblEnv TcLclEnv)) [VarBndr Var Specificity]
-> forall r.
   ([VarBndr Var Specificity]
    -> ZonkT (IOEnv (Env TcGblEnv TcLclEnv)) r)
   -> ZonkT (IOEnv (Env TcGblEnv TcLclEnv)) r
forall (m :: * -> *) a.
ZonkBndrT m a -> forall r. (a -> ZonkT m r) -> ZonkT m r
runZonkBndrT ([VarBndr Var Specificity]
-> ZonkBndrT
     (IOEnv (Env TcGblEnv TcLclEnv)) [VarBndr Var Specificity]
forall vis. [VarBndr Var vis] -> ZonkBndrTcM [VarBndr Var vis]
zonkTyVarBindersX [VarBndr Var Specificity]
exp_tvbndrs) (([VarBndr Var Specificity]
  -> ZonkT
       (IOEnv (Env TcGblEnv TcLclEnv))
       ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
        ThetaType))
 -> ZonkT
      (IOEnv (Env TcGblEnv TcLclEnv))
      ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
       ThetaType))
-> ([VarBndr Var Specificity]
    -> ZonkT
         (IOEnv (Env TcGblEnv TcLclEnv))
         ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
          ThetaType))
-> ZonkT
     (IOEnv (Env TcGblEnv TcLclEnv))
     ([TyConBinder], [Var], [VarBndr Var Specificity], [Scaled Type],
      ThetaType)
forall a b. (a -> b) -> a -> b
$ \ [VarBndr Var Specificity]
exp_tvbndrs ->
           do { arg_tys <- [Scaled Type] -> ZonkTcM [Scaled Type]
zonkScaledTcTypesToTypesX [Scaled Type]
arg_tys
              ; ctxt    <- zonkTcTypesToTypesX       ctxt
              ; return (tc_bndrs, kvs, exp_tvbndrs, arg_tys, ctxt) }

       -- Can't print univ_tvs, arg_tys etc, because we are inside the knot here
       ; traceTc "tcConDecl 2" (ppr name $$ ppr field_lbls)
       ; let univ_tvbs = [TyConBinder] -> [VarBndr Var Specificity]
tyConInvisTVBinders [TyConBinder]
tc_bndrs
             ex_tvbs   = Specificity -> [Var] -> [VarBndr Var Specificity]
forall vis. vis -> [Var] -> [VarBndr Var vis]
mkTyVarBinders Specificity
InferredSpec [Var]
kvs [VarBndr Var Specificity]
-> [VarBndr Var Specificity] -> [VarBndr Var Specificity]
forall a. [a] -> [a] -> [a]
++ [VarBndr Var Specificity]
exp_tvbndrs
             ex_tvs    = [VarBndr Var Specificity] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Var Specificity]
ex_tvbs
                -- For H98 datatypes, the user-written tyvar binders are precisely
                -- the universals followed by the existentials.
                -- See Note [DataCon user type variable binders] in GHC.Core.DataCon.
             user_tvbs = [VarBndr Var Specificity]
univ_tvbs [VarBndr Var Specificity]
-> [VarBndr Var Specificity] -> [VarBndr Var Specificity]
forall a. [a] -> [a] -> [a]
++ [VarBndr Var Specificity]
ex_tvbs
             user_res_ty = DataDeclInfo -> TyCon -> [TyConBinder] -> Type
mkDDHeaderTy DataDeclInfo
dd_info TyCon
rep_tycon [TyConBinder]
tc_bndrs

       ; traceTc "tcConDecl 2" (ppr name)
       ; is_infix <- tcConIsInfixH98 name hs_args
       ; rep_nm   <- newTyConRepName name
       ; fam_envs <- tcGetFamInstEnvs
       ; dflags   <- getDynFlags
       ; let bang_opts = BangOpts -> DataConBangOpts
SrcBangOpts (DynFlags -> BangOpts
initBangOpts DynFlags
dflags)
       ; dc <- buildDataCon fam_envs bang_opts name is_infix rep_nm
                            stricts field_lbls
                            tc_tvs ex_tvs user_tvbs
                            [{- no eq_preds -}] ctxt arg_tys
                            user_res_ty rep_tycon tag_map
                  -- NB:  we put data_tc, the type constructor gotten from the
                  --      constructor type signature into the data constructor;
                  --      that way checkValidDataCon can complain if it's wrong.

       ; return (NE.singleton dc) }

tcConDecl NewOrData
new_or_data DataDeclInfo
dd_info TyCon
rep_tycon [TyConBinder]
tc_bndrs Type
_res_kind NameEnv Int
tag_map
  -- NB: don't use res_kind here, as it's ill-scoped. Instead,
  -- we get the res_kind by typechecking the result type.
          (ConDeclGADT { con_names :: forall pass. ConDecl pass -> NonEmpty (LIdP pass)
con_names = NonEmpty (LIdP GhcRn)
names
                       , con_bndrs :: forall pass. ConDecl pass -> XRec pass (HsOuterSigTyVarBndrs pass)
con_bndrs = L SrcSpanAnnA
_ HsOuterSigTyVarBndrs GhcRn
outer_hs_bndrs
                       , con_mb_cxt :: forall pass. ConDecl pass -> Maybe (LHsContext pass)
con_mb_cxt = Maybe (LHsContext GhcRn)
cxt, con_g_args :: forall pass. ConDecl pass -> HsConDeclGADTDetails pass
con_g_args = HsConDeclGADTDetails GhcRn
hs_args
                       , con_res_ty :: forall pass. ConDecl pass -> LHsType pass
con_res_ty = LHsKind GhcRn
hs_res_ty })
  = SDoc -> TcM (NonEmpty DataCon) -> TcM (NonEmpty DataCon)
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (NonEmpty (LocatedN Name) -> SDoc
dataConCtxt NonEmpty (LIdP GhcRn)
NonEmpty (LocatedN Name)
names) (TcM (NonEmpty DataCon) -> TcM (NonEmpty DataCon))
-> TcM (NonEmpty DataCon) -> TcM (NonEmpty DataCon)
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"tcConDecl 1 gadt" (NonEmpty (LocatedN Name) -> SDoc
forall a. Outputable a => a -> SDoc
ppr NonEmpty (LIdP GhcRn)
NonEmpty (LocatedN Name)
names)
       ; let L SrcSpanAnnN
_ Name
name :| [LIdP GhcRn]
_ = NonEmpty (LIdP GhcRn)
names
       ; skol_info <- SkolemInfoAnon -> IOEnv (Env TcGblEnv TcLclEnv) SkolemInfo
forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
mkSkolemInfo (Name -> SkolemInfoAnon
DataConSkol Name
name)
       ; (tclvl, wanted, (outer_bndrs, (ctxt, arg_tys, res_ty, field_lbls, stricts)))
           <- pushLevelAndSolveEqualitiesX "tcConDecl:GADT" $
              tcOuterTKBndrs skol_info outer_hs_bndrs       $
              do { ctxt <- tcHsContext cxt
                 ; (res_ty, res_kind) <- tcInferLHsTypeKind hs_res_ty
                         -- See Note [GADT return kinds]

                 -- For data instances (only), ensure that the return type,
                 -- res_ty, is a substitution instance of the header.
                 -- See Note [GADT return types]
                 ; case dd_info of
                      DataDeclInfo
DDataType -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
                      DDataInstance Type
hdr_ty ->
                        do { (subst, _meta_tvs) <- [Var] -> TcM (Subst, [Var])
newMetaTyVars ([TyConBinder] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tc_bndrs)
                           ; let head_shape = HasDebugCallStack => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
subst Type
hdr_ty
                           ; discardResult $
                             popErrCtxt $  -- Drop dataConCtxt
                             addErrCtxt (dataConResCtxt names) $
                             unifyType Nothing res_ty head_shape }

                   -- See Note [Datatype return kinds]
                 ; let exp_kind = NewOrData -> Type -> ContextKind
getArgExpKind NewOrData
new_or_data Type
res_kind
                 ; btys <- tcConGADTArgs exp_kind hs_args

                 ; let (arg_tys, stricts) = unzip btys
                 ; field_lbls <- lookupConstructorFields name
                 ; return (ctxt, arg_tys, res_ty, field_lbls, stricts)
                 }

       ; outer_bndrs <- scopedSortOuter outer_bndrs
       ; let outer_tv_bndrs = HsOuterSigTyVarBndrs GhcTc -> [VarBndr Var Specificity]
outerTyVarBndrs HsOuterSigTyVarBndrs GhcTc
outer_bndrs

       ; tkvs <- kindGeneralizeAll skol_info
                    (mkInvisForAllTys outer_tv_bndrs $
                     tcMkPhiTy ctxt                  $
                     tcMkScaledFunTys arg_tys        $
                     res_ty)
       ; traceTc "tcConDecl:GADT" (ppr names $$ ppr res_ty $$ ppr tkvs)
       ; reportUnsolvedEqualities skol_info tkvs tclvl wanted

       ; let tvbndrs =  Specificity -> [Var] -> [VarBndr Var Specificity]
forall vis. vis -> [Var] -> [VarBndr Var vis]
mkTyVarBinders Specificity
InferredSpec [Var]
tkvs [VarBndr Var Specificity]
-> [VarBndr Var Specificity] -> [VarBndr Var Specificity]
forall a. [a] -> [a] -> [a]
++ [VarBndr Var Specificity]
outer_tv_bndrs

       -- Zonk to Types
       ; (tvbndrs, arg_tys, ctxt, res_ty) <- initZonkEnv NoFlexi $
         runZonkBndrT (zonkTyVarBindersX tvbndrs) $ \ [VarBndr Var Specificity]
tvbndrs ->
           do { arg_tys <- [Scaled Type] -> ZonkTcM [Scaled Type]
zonkScaledTcTypesToTypesX [Scaled Type]
arg_tys
              ; ctxt    <- zonkTcTypesToTypesX       ctxt
              ; res_ty  <- zonkTcTypeToTypeX         res_ty
              ; return (tvbndrs, arg_tys, ctxt, res_ty) }

       ; let res_tmpl = DataDeclInfo -> TyCon -> [TyConBinder] -> Type
mkDDHeaderTy DataDeclInfo
dd_info TyCon
rep_tycon [TyConBinder]
tc_bndrs
             (univ_tvs, ex_tvs, tvbndrs', eq_preds, arg_subst)
               = rejigConRes tc_bndrs res_tmpl tvbndrs res_ty
             -- See Note [rejigConRes]

             ctxt'      = HasDebugCallStack => Subst -> ThetaType -> ThetaType
Subst -> ThetaType -> ThetaType
substTys Subst
arg_subst ThetaType
ctxt
             arg_tys'   = HasDebugCallStack => Subst -> [Scaled Type] -> [Scaled Type]
Subst -> [Scaled Type] -> [Scaled Type]
substScaledTys Subst
arg_subst [Scaled Type]
arg_tys
             res_ty'    = HasDebugCallStack => Subst -> Type -> Type
Subst -> Type -> Type
substTy  Subst
arg_subst Type
res_ty

       -- Can't print univ_tvs, arg_tys etc, because we are inside the knot here
       ; traceTc "tcConDecl 2" (ppr names $$ ppr field_lbls)
       ; fam_envs <- tcGetFamInstEnvs
       ; dflags <- getDynFlags
       ; let
           buildOneDataCon (L SrcSpanAnnN
_ Name
name) = do
             { is_infix <- Name -> HsConDeclGADTDetails GhcRn -> TcRnIf TcGblEnv TcLclEnv Bool
tcConIsInfixGADT Name
name HsConDeclGADTDetails GhcRn
hs_args
             ; rep_nm   <- newTyConRepName name

             ; let bang_opts = BangOpts -> DataConBangOpts
SrcBangOpts (DynFlags -> BangOpts
initBangOpts DynFlags
dflags)
             ; buildDataCon fam_envs bang_opts name is_infix
                            rep_nm stricts field_lbls
                            univ_tvs ex_tvs tvbndrs' eq_preds
                            ctxt' arg_tys' res_ty' rep_tycon tag_map
                  -- NB:  we put data_tc, the type constructor gotten from the
                  --      constructor type signature into the data constructor;
                  --      that way checkValidDataCon can complain if it's wrong.
             }
       ; mapM buildOneDataCon names }

{- Note [GADT return types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
  data family T :: forall k. k -> Type
  data instance T (a :: Type) where
    MkT :: forall b. T b

What kind does `b` have in the signature for MkT?
Since the return type must be an instance of the type in the header,
we must have (b :: Type), but you can't tell that by looking only at
the type of the data constructor; you have to look at the header too.
If you wrote it out fully, it'd look like
  data instance T @Type (a :: Type) where
    MkT :: forall (b::Type). T @Type b

We could reject the program, and expect the user to add kind
annotations to `MkT` to restrict the signature.  But an easy and
helpful alternative is this: simply instantiate the type from the
header with fresh unification variables, and unify with the return
type of `MkT`. That will force `b` to have kind `Type`.  See #8707
and #14111.

Wrikles
* At first sight it looks as though this would completely subsume the
  return-type check in checkValidDataCon.  But it does not. Suppose we
  have
     data instance T [a] where
        MkT :: T (F (Maybe a))

  where F is a type function.  Then maybe (F (Maybe a)) evaluates to
  [a], so unifyType will succeed.  But we discard the coercion
  returned by unifyType; and we really don't want to accept this
  program.  The check in checkValidDataCon will, however, reject it.
  TL;DR: keep the check in checkValidDataCon.

* Consider a data type, rather than a data instance, declaration
     data S a where { MkS :: b -> S [b]  }
  In tcConDecl, S is knot-tied, so we don't want to unify (S alpha)
  with (S [b]). To put it another way, unifyType should never see a
  TcTycon.  Simple solution: do *not* do the extra unifyType for
  data types (DDataType) only for data instances (DDataInstance); in
  the latter the family constructor is not knot-tied so there is no
  problem.

* Consider this (from an earlier form of GHC itself):

     data Pass = Parsed | ...
     data GhcPass (c :: Pass) where
       GhcPs :: GhcPs
       ...
     type GhcPs   = GhcPass 'Parsed

   Now GhcPs and GhcPass are mutually recursive. If we did unifyType
   for datatypes like GhcPass, we would not be able to expand the type
   synonym (it'd still be a TcTyCon).  So again, we don't do unifyType
   for data types; we leave it to checkValidDataCon.

   We /do/ perform the unifyType for data /instances/, but a data
   instance doesn't declare a new (user-visible) type constructor, so
   there is no mutual recursion with type synonyms to worry about.
   All good.

   TL;DR we do support mutual recursion between type synonyms and
   data type/instance declarations, as above.

Note [GADT return kinds]
~~~~~~~~~~~~~~~~~~~~~~~~
Consider
   type family Star where Star = Type
   data T :: Type where
      MkT :: Int -> T

If, for some stupid reason, tcInferLHsTypeKind on the return type of
MkT returned (T |> ax, Star), then the return-type check in
checkValidDataCon would reject the decl (although of course there is
nothing wrong with it).  We are implicitly requiring tha
tcInferLHsTypeKind doesn't any gratuitous top-level casts.
-}

-- | Produce an "expected kind" for the arguments of a data/newtype.
-- If the declaration is indeed for a newtype,
-- then this expected kind will be the kind provided. Otherwise,
-- it is OpenKind for datatypes and liftedTypeKind.
-- Why do we not check for -XUnliftedNewtypes? See point <Error Messages>
-- in Note [Implementation of UnliftedNewtypes]
getArgExpKind :: NewOrData -> TcKind -> ContextKind
getArgExpKind :: NewOrData -> Type -> ContextKind
getArgExpKind NewOrData
NewType Type
res_ki = Type -> ContextKind
TheKind Type
res_ki
getArgExpKind NewOrData
DataType Type
_     = ContextKind
OpenKind

tcConIsInfixH98 :: Name
             -> HsConDeclH98Details GhcRn
             -> TcM Bool
tcConIsInfixH98 :: Name -> HsConDeclH98Details GhcRn -> TcRnIf TcGblEnv TcLclEnv Bool
tcConIsInfixH98 Name
_   HsConDeclH98Details GhcRn
details
  = case HsConDeclH98Details GhcRn
details of
           InfixCon{}  -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
True
           RecCon{}    -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
           PrefixCon{} -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False

tcConIsInfixGADT :: Name
             -> HsConDeclGADTDetails GhcRn
             -> TcM Bool
tcConIsInfixGADT :: Name -> HsConDeclGADTDetails GhcRn -> TcRnIf TcGblEnv TcLclEnv Bool
tcConIsInfixGADT Name
con HsConDeclGADTDetails GhcRn
details
  = case HsConDeclGADTDetails GhcRn
details of
           RecConGADT{} -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
           PrefixConGADT XPrefixConGADT GhcRn
_ [HsScaled GhcRn (LHsKind GhcRn)]
arg_tys       -- See Note [Infix GADT constructors]
               | OccName -> Bool
isSymOcc (Name -> OccName
forall a. NamedThing a => a -> OccName
getOccName Name
con)
               , [GenLocated SrcSpanAnnA (HsType GhcRn)
_ty1,GenLocated SrcSpanAnnA (HsType GhcRn)
_ty2] <- (HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
 -> GenLocated SrcSpanAnnA (HsType GhcRn))
-> [HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> [GenLocated SrcSpanAnnA (HsType GhcRn)]
forall a b. (a -> b) -> [a] -> [b]
map HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
-> GenLocated SrcSpanAnnA (HsType GhcRn)
forall pass a. HsScaled pass a -> a
hsScaledThing [HsScaled GhcRn (LHsKind GhcRn)]
[HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
arg_tys
                  -> do { fix_env <- TcRn FixityEnv
getFixityEnv
                        ; return (con `elemNameEnv` fix_env) }
               | Bool
otherwise -> Bool -> TcRnIf TcGblEnv TcLclEnv Bool
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False

tcConH98Args :: ContextKind  -- expected kind of arguments
                             -- always OpenKind for datatypes, but unlifted newtypes
                             -- might have a specific kind
             -> HsConDeclH98Details GhcRn
             -> TcM [(Scaled TcType, HsSrcBang)]
tcConH98Args :: ContextKind
-> HsConDeclH98Details GhcRn -> TcM [(Scaled Type, HsSrcBang)]
tcConH98Args ContextKind
exp_kind (PrefixCon [Void]
_ [HsScaled GhcRn (LHsKind GhcRn)]
btys)
  = (HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
 -> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang))
-> [HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> TcM [(Scaled Type, HsSrcBang)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM (ContextKind
-> HsScaled GhcRn (LHsKind GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang)
tcConArg ContextKind
exp_kind) [HsScaled GhcRn (LHsKind GhcRn)]
[HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
btys
tcConH98Args ContextKind
exp_kind (InfixCon HsScaled GhcRn (LHsKind GhcRn)
bty1 HsScaled GhcRn (LHsKind GhcRn)
bty2)
  = do { bty1' <- ContextKind
-> HsScaled GhcRn (LHsKind GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang)
tcConArg ContextKind
exp_kind HsScaled GhcRn (LHsKind GhcRn)
bty1
       ; bty2' <- tcConArg exp_kind bty2
       ; return [bty1', bty2'] }
tcConH98Args ContextKind
exp_kind (RecCon XRec GhcRn [LConDeclField GhcRn]
fields)
  = ContextKind
-> LocatedL [LConDeclField GhcRn] -> TcM [(Scaled Type, HsSrcBang)]
tcRecConDeclFields ContextKind
exp_kind XRec GhcRn [LConDeclField GhcRn]
LocatedL [LConDeclField GhcRn]
fields

tcConGADTArgs :: ContextKind  -- expected kind of arguments
                              -- always OpenKind for datatypes, but unlifted newtypes
                              -- might have a specific kind
              -> HsConDeclGADTDetails GhcRn
              -> TcM [(Scaled TcType, HsSrcBang)]
tcConGADTArgs :: ContextKind
-> HsConDeclGADTDetails GhcRn -> TcM [(Scaled Type, HsSrcBang)]
tcConGADTArgs ContextKind
exp_kind (PrefixConGADT XPrefixConGADT GhcRn
_ [HsScaled GhcRn (LHsKind GhcRn)]
btys)
  = (HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))
 -> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang))
-> [HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
-> TcM [(Scaled Type, HsSrcBang)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM (ContextKind
-> HsScaled GhcRn (LHsKind GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang)
tcConArg ContextKind
exp_kind) [HsScaled GhcRn (LHsKind GhcRn)]
[HsScaled GhcRn (GenLocated SrcSpanAnnA (HsType GhcRn))]
btys
tcConGADTArgs ContextKind
exp_kind (RecConGADT XRecConGADT GhcRn
_ XRec GhcRn [LConDeclField GhcRn]
fields)
  = ContextKind
-> LocatedL [LConDeclField GhcRn] -> TcM [(Scaled Type, HsSrcBang)]
tcRecConDeclFields ContextKind
exp_kind XRec GhcRn [LConDeclField GhcRn]
LocatedL [LConDeclField GhcRn]
fields

tcConArg :: ContextKind  -- expected kind for args; always OpenKind for datatypes,
                         -- but might be an unlifted type with UnliftedNewtypes
         -> HsScaled GhcRn (LHsType GhcRn) -> TcM (Scaled TcType, HsSrcBang)
tcConArg :: ContextKind
-> HsScaled GhcRn (LHsKind GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang)
tcConArg ContextKind
exp_kind (HsScaled HsArrow GhcRn
w LHsKind GhcRn
bty)
  = do  { String -> SDoc -> TcRn ()
traceTc String
"tcConArg 1" (GenLocated SrcSpanAnnA (HsType GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr LHsKind GhcRn
GenLocated SrcSpanAnnA (HsType GhcRn)
bty)
        ; arg_ty <- LHsKind GhcRn -> ContextKind -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcCheckLHsType (LHsKind GhcRn -> LHsKind GhcRn
forall (p :: Pass). LHsType (GhcPass p) -> LHsType (GhcPass p)
getBangType LHsKind GhcRn
bty) ContextKind
exp_kind
        ; w' <- tcDataConMult w
        ; traceTc "tcConArg 2" (ppr bty)
        ; return (Scaled w' arg_ty, getBangStrictness bty) }

tcRecConDeclFields :: ContextKind
                   -> LocatedL [LConDeclField GhcRn]
                   -> TcM [(Scaled TcType, HsSrcBang)]
tcRecConDeclFields :: ContextKind
-> LocatedL [LConDeclField GhcRn] -> TcM [(Scaled Type, HsSrcBang)]
tcRecConDeclFields ContextKind
exp_kind LocatedL [LConDeclField GhcRn]
fields
  = (HsScaled GhcRn (LHsKind GhcRn)
 -> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang))
-> [HsScaled GhcRn (LHsKind GhcRn)]
-> TcM [(Scaled Type, HsSrcBang)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
forall (m :: * -> *) a b. Monad m => (a -> m b) -> [a] -> m [b]
mapM (ContextKind
-> HsScaled GhcRn (LHsKind GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Scaled Type, HsSrcBang)
tcConArg ContextKind
exp_kind) [HsScaled GhcRn (LHsKind GhcRn)]
btys
  where
    -- We need a one-to-one mapping from field_names to btys
    combined :: [([XRec GhcRn (FieldOcc GhcRn)], HsScaled GhcRn (LHsKind GhcRn))]
combined = (GenLocated SrcSpanAnnA (ConDeclField GhcRn)
 -> ([XRec GhcRn (FieldOcc GhcRn)], HsScaled GhcRn (LHsKind GhcRn)))
-> [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
-> [([XRec GhcRn (FieldOcc GhcRn)],
     HsScaled GhcRn (LHsKind GhcRn))]
forall a b. (a -> b) -> [a] -> [b]
map (\(L SrcSpanAnnA
_ ConDeclField GhcRn
f) -> (ConDeclField GhcRn -> [XRec GhcRn (FieldOcc GhcRn)]
forall pass. ConDeclField pass -> [LFieldOcc pass]
cd_fld_names ConDeclField GhcRn
f,LHsKind GhcRn -> HsScaled GhcRn (LHsKind GhcRn)
forall (p :: Pass) a. IsPass p => a -> HsScaled (GhcPass p) a
hsLinear (ConDeclField GhcRn -> LHsKind GhcRn
forall pass. ConDeclField pass -> LBangType pass
cd_fld_type ConDeclField GhcRn
f)))
                   (GenLocated
  SrcSpanAnnL [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
-> [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
forall l e. GenLocated l e -> e
unLoc LocatedL [LConDeclField GhcRn]
GenLocated
  SrcSpanAnnL [GenLocated SrcSpanAnnA (ConDeclField GhcRn)]
fields)
    explode :: ([a], b) -> [(a, b)]
explode ([a]
ns,b
ty) = [a] -> [b] -> [(a, b)]
forall a b. [a] -> [b] -> [(a, b)]
zip [a]
ns (b -> [b]
forall a. a -> [a]
repeat b
ty)
    exploded :: [(XRec GhcRn (FieldOcc GhcRn), HsScaled GhcRn (LHsKind GhcRn))]
exploded = (([XRec GhcRn (FieldOcc GhcRn)], HsScaled GhcRn (LHsKind GhcRn))
 -> [(XRec GhcRn (FieldOcc GhcRn), HsScaled GhcRn (LHsKind GhcRn))])
-> [([XRec GhcRn (FieldOcc GhcRn)],
     HsScaled GhcRn (LHsKind GhcRn))]
-> [(XRec GhcRn (FieldOcc GhcRn), HsScaled GhcRn (LHsKind GhcRn))]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap ([XRec GhcRn (FieldOcc GhcRn)], HsScaled GhcRn (LHsKind GhcRn))
-> [(XRec GhcRn (FieldOcc GhcRn), HsScaled GhcRn (LHsKind GhcRn))]
forall {a} {b}. ([a], b) -> [(a, b)]
explode [([XRec GhcRn (FieldOcc GhcRn)], HsScaled GhcRn (LHsKind GhcRn))]
combined
    ([XRec GhcRn (FieldOcc GhcRn)]
_,[HsScaled GhcRn (LHsKind GhcRn)]
btys) = [(XRec GhcRn (FieldOcc GhcRn), HsScaled GhcRn (LHsKind GhcRn))]
-> ([XRec GhcRn (FieldOcc GhcRn)],
    [HsScaled GhcRn (LHsKind GhcRn)])
forall a b. [(a, b)] -> ([a], [b])
unzip [(XRec GhcRn (FieldOcc GhcRn), HsScaled GhcRn (LHsKind GhcRn))]
exploded

tcDataConMult :: HsArrow GhcRn -> TcM Mult
tcDataConMult :: HsArrow GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcDataConMult arr :: HsArrow GhcRn
arr@(HsUnrestrictedArrow XUnrestrictedArrow GhcRn
_) = do
  -- See Note [Function arrows in GADT constructors]
  linearEnabled <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.LinearTypes
  if linearEnabled then tcMult arr else return oneDataConTy
tcDataConMult HsArrow GhcRn
arr = HsArrow GhcRn -> IOEnv (Env TcGblEnv TcLclEnv) Type
tcMult HsArrow GhcRn
arr

{-
Note [Function arrows in GADT constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the absence of -XLinearTypes, we always interpret function arrows
in GADT constructor types as linear, even if the user wrote an
unrestricted arrow. See the "Without -XLinearTypes" section of the
linear types GHC proposal (#111). We opt to do this in the
typechecker, and not in an earlier pass, to ensure that the AST
matches what the user wrote (#18791).

Note [Infix GADT constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We do not currently have syntax to declare an infix constructor in GADT syntax,
but it makes a (small) difference to the Show instance.  So as a slightly
ad-hoc solution, we regard a GADT data constructor as infix if
  a) it is an operator symbol
  b) it has two arguments
  c) there is a fixity declaration for it
For example:
   infix 6 (:--:)
   data T a where
     (:--:) :: t1 -> t2 -> T Int


Note [rejigConRes]
~~~~~~~~~~~~~~~~~~
There is a delicacy around checking the return types of a datacon. The
central problem is dealing with a declaration like

  data T a where
    MkT :: T a -> Q a

Note that the return type of MkT is totally bogus. When creating the T
tycon, we also need to create the MkT datacon, which must have a "rejigged"
return type. That is, the MkT datacon's type must be transformed to have
a uniform return type with explicit coercions for GADT-like type parameters.
This rejigging is what rejigConRes does. The problem is, though, that checking
that the return type is appropriate is much easier when done over *Type*,
not *HsType*, and doing a call to tcMatchTy will loop because T isn't fully
defined yet.

So, we want to make rejigConRes lazy and then check the validity of
the return type in checkValidDataCon.  To do this we /always/ return a
6-tuple from rejigConRes (so that we can compute the return type from it, which
checkValidDataCon needs), but the first three fields may be bogus if
the return type isn't valid (the last equation for rejigConRes).

This is better than an earlier solution which reduced the number of
errors reported in one pass.  See #7175, and #10836.
-}

-- Example
--   data instance T (b,c) where
--      TI :: forall e. e -> T (e,e)
--
-- The representation tycon looks like this:
--   data :R7T b c where
--      TI :: forall b1 c1. (b1 ~ c1) => b1 -> :R7T b1 c1
-- In this case orig_res_ty = T (e,e)

rejigConRes :: [KnotTied TyConBinder]  -- Template for result type; e.g.
            -> KnotTied Type           -- data instance T [a] b c ...
                                       --      gives template ([a,b,c], T [a] b c)
            -> [InvisTVBinder]    -- The constructor's type variables (both inferred and user-written)
            -> KnotTied Type      -- res_ty
            -> ([TyVar],          -- Universal
                [TyVar],          -- Existential (distinct OccNames from univs)
                [InvisTVBinder],  -- The constructor's rejigged, user-written
                                  -- type variables
                [EqSpec],         -- Equality predicates
                Subst)            -- Substitution to apply to argument types
        -- We don't check that the TyCon given in the ResTy is
        -- the same as the parent tycon, because checkValidDataCon will do it
-- NB: All arguments may potentially be knot-tied
rejigConRes :: [TyConBinder]
-> Type
-> [VarBndr Var Specificity]
-> Type
-> ([Var], [Var], [VarBndr Var Specificity], [EqSpec], Subst)
rejigConRes [TyConBinder]
tc_tvbndrs Type
res_tmpl [VarBndr Var Specificity]
dc_tvbndrs Type
res_ty
        -- E.g.  data T [a] b c where
        --         MkT :: forall x y z. T [(x,y)] z z
        -- The {a,b,c} are the tc_tvs, and the {x,y,z} are the dc_tvs
        --     (NB: unlike the H98 case, the dc_tvs are not all existential)
        -- Then we generate
        --      Univ tyvars     Eq-spec
        --          a              a~(x,y)
        --          b              b~z
        --          z
        -- Existentials are the leftover type vars: [x,y]
        -- The user-written type variables are what is listed in the forall:
        --   [x, y, z] (all specified). We must rejig these as well.
        --   See Note [DataCon user type variable binders] in GHC.Core.DataCon.
        -- So we return ( [a,b,z], [x,y]
        --              , [], [x,y,z]
        --              , [a~(x,y),b~z], <arg-subst> )
  | Just Subst
subst <- Type -> Type -> Maybe Subst
tcMatchTy Type
res_tmpl Type
res_ty
  = let ([Var]
univ_tvs, [(Var, Type)]
raw_eqs, Subst
kind_subst) = [Var] -> [Var] -> Subst -> ([Var], [(Var, Type)], Subst)
mkGADTVars [Var]
tc_tvs [Var]
dc_tvs Subst
subst
        raw_ex_tvs :: [Var]
raw_ex_tvs = [Var]
dc_tvs [Var] -> [Var] -> [Var]
forall a. Ord a => [a] -> [a] -> [a]
`minusList` [Var]
univ_tvs
        (Subst
arg_subst, [Var]
substed_ex_tvs) = HasDebugCallStack => Subst -> [Var] -> (Subst, [Var])
Subst -> [Var] -> (Subst, [Var])
substTyVarBndrs Subst
kind_subst [Var]
raw_ex_tvs

        -- After rejigging the existential tyvars, the resulting substitution
        -- gives us exactly what we need to rejig the user-written tyvars,
        -- since the dcUserTyVarBinders invariant guarantees that the
        -- substitution has *all* the tyvars in its domain.
        -- See Note [DataCon user type variable binders] in GHC.Core.DataCon.
        subst_user_tvs :: [VarBndr Var Specificity] -> [VarBndr Var Specificity]
subst_user_tvs  = (Var -> Var)
-> [VarBndr Var Specificity] -> [VarBndr Var Specificity]
forall var var' flag.
(var -> var') -> [VarBndr var flag] -> [VarBndr var' flag]
mapVarBndrs (HasDebugCallStack => Subst -> Var -> Var
Subst -> Var -> Var
substTyVarToTyVar Subst
arg_subst)
        substed_tvbndrs :: [VarBndr Var Specificity]
substed_tvbndrs = [VarBndr Var Specificity] -> [VarBndr Var Specificity]
subst_user_tvs [VarBndr Var Specificity]
dc_tvbndrs

        substed_eqs :: [EqSpec]
substed_eqs = [ Var -> Type -> EqSpec
mkEqSpec (HasDebugCallStack => Subst -> Var -> Var
Subst -> Var -> Var
substTyVarToTyVar Subst
arg_subst Var
tv)
                                 (HasDebugCallStack => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
arg_subst Type
ty)
                      | (Var
tv,Type
ty) <- [(Var, Type)]
raw_eqs ]
    in
    ([Var]
univ_tvs, [Var]
substed_ex_tvs, [VarBndr Var Specificity]
substed_tvbndrs, [EqSpec]
substed_eqs, Subst
arg_subst)

  | Bool
otherwise
        -- If the return type of the data constructor doesn't match the parent
        -- type constructor, or the arity is wrong, the tcMatchTy will fail
        --    e.g   data T a b where
        --            T1 :: Maybe a   -- Wrong tycon
        --            T2 :: T [a]     -- Wrong arity
        -- We are detect that later, in checkValidDataCon, but meanwhile
        -- we must do *something*, not just crash.  So we do something simple
        -- albeit bogus, relying on checkValidDataCon to check the
        --  bad-result-type error before seeing that the other fields look odd
        -- See Note [rejigConRes]
  = ([Var]
tc_tvs, [Var]
dc_tvs [Var] -> [Var] -> [Var]
forall a. Ord a => [a] -> [a] -> [a]
`minusList` [Var]
tc_tvs, [VarBndr Var Specificity]
dc_tvbndrs, [], Subst
emptySubst)
  where
    dc_tvs :: [Var]
dc_tvs = [VarBndr Var Specificity] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Var Specificity]
dc_tvbndrs
    tc_tvs :: [Var]
tc_tvs = [TyConBinder] -> [Var]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [TyConBinder]
tc_tvbndrs

{- Note [mkGADTVars]
~~~~~~~~~~~~~~~~~~~~
Running example:

data T (k1 :: *) (k2 :: *) (a :: k2) (b :: k2) where
  MkT :: forall (x1 : *) (y :: x1) (z :: *).
         T x1 * (Proxy (y :: x1), z) z

We need the rejigged type to be

  MkT :: forall (x1 :: *) (k2 :: *) (a :: k2) (b :: k2).
         forall (y :: x1) (z :: *).
         (k2 ~ *, a ~ (Proxy x1 y, z), b ~ z)
      => T x1 k2 a b

You might naively expect that z should become a universal tyvar,
not an existential. (After all, x1 becomes a universal tyvar.)
But z has kind * while b has kind k2, so the return type
   T x1 k2 a z
is ill-kinded.  Another way to say it is this: the universal
tyvars must have exactly the same kinds as the tyConTyVars.

So we need an existential tyvar and a heterogeneous equality
constraint. (The b ~ z is a bit redundant with the k2 ~ * that
comes before in that b ~ z implies k2 ~ *. I'm sure we could do
some analysis that could eliminate k2 ~ *. But we don't do this
yet.)

The data con signature has already been fully kind-checked.
The return type

  T x1 * (Proxy (y :: x1), z) z
becomes
  qtkvs    = [x1 :: *, y :: x1, z :: *]
  res_tmpl = T x1 * (Proxy x1 y, z) z

We start off by matching (T k1 k2 a b) with (T x1 * (Proxy x1 y, z) z). We
know this match will succeed because of the validity check (actually done
later, but laziness saves us -- see Note [rejigConRes]).
Thus, we get

  subst := { k1 |-> x1, k2 |-> *, a |-> (Proxy x1 y, z), b |-> z }

Now, we need to figure out what the GADT equalities should be. In this case,
we *don't* want (k1 ~ x1) to be a GADT equality: it should just be a
renaming. The others should be GADT equalities. We also need to make
sure that the universally-quantified variables of the datacon match up
with the tyvars of the tycon, as required for Core context well-formedness.
(This last bit is why we have to rejig at all!)

`choose` walks down the tycon tyvars, figuring out what to do with each one.
It carries two substitutions:
  - t_sub's domain is *template* or *tycon* tyvars, mapping them to variables
    mentioned in the datacon signature.
  - r_sub's domain is *result* tyvars, names written by the programmer in
    the datacon signature. The final rejigged type will use these names, but
    the subst is still needed because sometimes the printed name of these variables
    is different. (See choose_tv_name, below.)

Before explaining the details of `choose`, let's just look at its operation
on our example:

  choose [] [] {} {} [k1, k2, a, b]
  -->          -- first branch of `case` statement
  choose
    univs:    [x1 :: *]
    eq_spec:  []
    t_sub:    {k1 |-> x1}
    r_sub:    {x1 |-> x1}
    t_tvs:    [k2, a, b]
  -->          -- second branch of `case` statement
  choose
    univs:    [k2 :: *, x1 :: *]
    eq_spec:  [k2 ~ *]
    t_sub:    {k1 |-> x1, k2 |-> k2}
    r_sub:    {x1 |-> x1}
    t_tvs:    [a, b]
  -->          -- second branch of `case` statement
  choose
    univs:    [a :: k2, k2 :: *, x1 :: *]
    eq_spec:  [ a ~ (Proxy x1 y, z)
              , k2 ~ * ]
    t_sub:    {k1 |-> x1, k2 |-> k2, a |-> a}
    r_sub:    {x1 |-> x1}
    t_tvs:    [b]
  -->          -- second branch of `case` statement
  choose
    univs:    [b :: k2, a :: k2, k2 :: *, x1 :: *]
    eq_spec:  [ b ~ z
              , a ~ (Proxy x1 y, z)
              , k2 ~ * ]
    t_sub:    {k1 |-> x1, k2 |-> k2, a |-> a, b |-> z}
    r_sub:    {x1 |-> x1}
    t_tvs:    []
  -->          -- end of recursion
  ( [x1 :: *, k2 :: *, a :: k2, b :: k2]
  , [k2 ~ *, a ~ (Proxy x1 y, z), b ~ z]
  , {x1 |-> x1} )

`choose` looks up each tycon tyvar in the matching (it *must* be matched!).

* If it finds a bare result tyvar (the first branch of the `case`
  statement), it checks to make sure that the result tyvar isn't yet
  in the list of univ_tvs.  If it is in that list, then we have a
  repeated variable in the return type, and we in fact need a GADT
  equality.

* It then checks to make sure that the kind of the result tyvar
  matches the kind of the template tyvar. This check is what forces
  `z` to be existential, as it should be, explained above.

* Assuming no repeated variables or kind-changing, we wish to use the
  variable name given in the datacon signature (that is, `x1` not
  `k1`), not the tycon signature (which may have been made up by
  GHC). So, we add a mapping from the tycon tyvar to the result tyvar
  to t_sub.

* If we discover that a mapping in `subst` gives us a non-tyvar (the
  second branch of the `case` statement), then we have a GADT equality
  to create.  We create a fresh equality, but we don't extend any
  substitutions. The template variable substitution is meant for use
  in universal tyvar kinds, and these shouldn't be affected by any
  GADT equalities.

This whole algorithm is quite delicate, indeed. I (Richard E.) see two ways
of simplifying it:

1) The first branch of the `case` statement is really an optimization, used
in order to get fewer GADT equalities. It might be possible to make a GADT
equality for *every* univ. tyvar, even if the equality is trivial, and then
either deal with the bigger type or somehow reduce it later.

2) This algorithm strives to use the names for type variables as specified
by the user in the datacon signature. If we always used the tycon tyvar
names, for example, this would be simplified. This change would almost
certainly degrade error messages a bit, though.
-}

-- | From information about a source datacon definition, extract out
-- what the universal variables and the GADT equalities should be.
-- See Note [mkGADTVars].
mkGADTVars :: [TyVar]    -- ^ The tycon vars
           -> [TyVar]    -- ^ The datacon vars
           -> Subst   -- ^ The matching between the template result type
                         -- and the actual result type
           -> ( [TyVar]
              , [(TyVar,Type)]   -- The un-substituted eq-spec
              , Subst ) -- ^ The univ. variables, the GADT equalities,
                           -- and a subst to apply to the GADT equalities
                           -- and existentials.
mkGADTVars :: [Var] -> [Var] -> Subst -> ([Var], [(Var, Type)], Subst)
mkGADTVars [Var]
tmpl_tvs [Var]
dc_tvs Subst
subst
  = [Var]
-> [(Var, Type)]
-> Subst
-> Subst
-> [Var]
-> ([Var], [(Var, Type)], Subst)
choose [] [] Subst
empty_subst Subst
empty_subst [Var]
tmpl_tvs
  where
    in_scope :: InScopeSet
in_scope = VarSet -> InScopeSet
mkInScopeSet ([Var] -> VarSet
mkVarSet [Var]
tmpl_tvs VarSet -> VarSet -> VarSet
`unionVarSet` [Var] -> VarSet
mkVarSet [Var]
dc_tvs)
               InScopeSet -> InScopeSet -> InScopeSet
`unionInScope` Subst -> InScopeSet
getSubstInScope Subst
subst
    empty_subst :: Subst
empty_subst = InScopeSet -> Subst
mkEmptySubst InScopeSet
in_scope

    choose :: [TyVar]        -- accumulator of univ tvs, reversed
           -> [(TyVar,Type)] -- accumulator of GADT equalities, reversed
           -> Subst          -- template substitution
           -> Subst          -- res. substitution
           -> [TyVar]           -- template tvs (the univ tvs passed in)
           -> ( [TyVar]         -- the univ_tvs
              , [(TyVar,Type)]  -- GADT equalities
              , Subst )       -- a substitution to fix kinds in ex_tvs

    choose :: [Var]
-> [(Var, Type)]
-> Subst
-> Subst
-> [Var]
-> ([Var], [(Var, Type)], Subst)
choose [Var]
univs [(Var, Type)]
eqs Subst
_t_sub Subst
r_sub []
      = ([Var] -> [Var]
forall a. [a] -> [a]
reverse [Var]
univs, [(Var, Type)] -> [(Var, Type)]
forall a. [a] -> [a]
reverse [(Var, Type)]
eqs, Subst
r_sub)
    choose [Var]
univs [(Var, Type)]
eqs Subst
t_sub Subst
r_sub (Var
t_tv:[Var]
t_tvs)
      | Just Type
r_ty <- Subst -> Var -> Maybe Type
lookupTyVar Subst
subst Var
t_tv
      = case Type -> Maybe Var
getTyVar_maybe Type
r_ty of
          Just Var
r_tv
            |  Bool -> Bool
not (Var
r_tv Var -> [Var] -> Bool
forall a. Eq a => a -> [a] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [Var]
univs)
            ,  Var -> Type
tyVarKind Var
r_tv Type -> Type -> Bool
`eqType` (HasDebugCallStack => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
t_sub (Var -> Type
tyVarKind Var
t_tv))
            -> -- simple, well-kinded variable substitution.
               -- the name of the universal comes from the result of the ctor
               -- see (R2) of Note [DataCon user type variable binders] in GHC.Core.DataCon
               [Var]
-> [(Var, Type)]
-> Subst
-> Subst
-> [Var]
-> ([Var], [(Var, Type)], Subst)
choose (Var
r_tvVar -> [Var] -> [Var]
forall a. a -> [a] -> [a]
:[Var]
univs) [(Var, Type)]
eqs
                      (Subst -> Var -> Type -> Subst
extendTvSubst Subst
t_sub Var
t_tv Type
r_ty')
                      (Subst -> Var -> Type -> Subst
extendTvSubst Subst
r_sub Var
r_tv Type
r_ty')
                      [Var]
t_tvs
            where
              r_tv1 :: Var
r_tv1  = Var -> Name -> Var
setTyVarName Var
r_tv (Var -> Var -> Name
choose_tv_name Var
r_tv Var
t_tv)
              r_ty' :: Type
r_ty'  = Var -> Type
mkTyVarTy Var
r_tv1

               -- Not a simple substitution: make an equality predicate
               -- the name of the universal comes from the datatype header
               -- see (R2) of Note [DataCon user type variable binders] in GHC.Core.DataCon
          Maybe Var
_ -> [Var]
-> [(Var, Type)]
-> Subst
-> Subst
-> [Var]
-> ([Var], [(Var, Type)], Subst)
choose (Var
t_tv'Var -> [Var] -> [Var]
forall a. a -> [a] -> [a]
:[Var]
univs) [(Var, Type)]
eqs'
                      (Subst -> Var -> Type -> Subst
extendTvSubst Subst
t_sub Var
t_tv (Var -> Type
mkTyVarTy Var
t_tv'))
                         -- We've updated the kind of t_tv,
                         -- so add it to t_sub (#14162)
                      Subst
r_sub [Var]
t_tvs
            where
              tv_kind :: Type
tv_kind  = Var -> Type
tyVarKind Var
t_tv
              tv_kind' :: Type
tv_kind' = HasDebugCallStack => Subst -> Type -> Type
Subst -> Type -> Type
substTy Subst
t_sub Type
tv_kind
              t_tv' :: Var
t_tv'    = Var -> Type -> Var
setTyVarKind Var
t_tv Type
tv_kind'
              eqs' :: [(Var, Type)]
eqs'     = (Var
t_tv', Type
r_ty) (Var, Type) -> [(Var, Type)] -> [(Var, Type)]
forall a. a -> [a] -> [a]
: [(Var, Type)]
eqs

      | Bool
otherwise
      = [Var]
-> [(Var, Type)]
-> Subst
-> Subst
-> [Var]
-> ([Var], [(Var, Type)], Subst)
choose (Var
t_tvVar -> [Var] -> [Var]
forall a. a -> [a] -> [a]
:[Var]
univs) [(Var, Type)]
eqs Subst
t_sub Subst
r_sub [Var]
t_tvs

      -- choose an appropriate name for a univ tyvar.
      -- This *must* preserve the Unique of the result tv, so that we
      -- can detect repeated variables. It prefers user-specified names
      -- over system names. A result variable with a system name can
      -- happen with GHC-generated implicit kind variables.
    choose_tv_name :: TyVar -> TyVar -> Name
    choose_tv_name :: Var -> Var -> Name
choose_tv_name Var
r_tv Var
t_tv
      | Name -> Bool
isSystemName Name
r_tv_name
      = Name -> Unique -> Name
setNameUnique Name
t_tv_name (Name -> Unique
forall a. Uniquable a => a -> Unique
getUnique Name
r_tv_name)

      | Bool
otherwise
      = Name
r_tv_name

      where
        r_tv_name :: Name
r_tv_name = Var -> Name
forall a. NamedThing a => a -> Name
getName Var
r_tv
        t_tv_name :: Name
t_tv_name = Var -> Name
forall a. NamedThing a => a -> Name
getName Var
t_tv

{-
Note [Substitution in template variables kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

data G (a :: Maybe k) where
  MkG :: G Nothing

With explicit kind variables

data G k (a :: Maybe k) where
  MkG :: G k1 (Nothing k1)

Note how k1 is distinct from k. So, when we match the template
`G k a` against `G k1 (Nothing k1)`, we get a subst
[ k |-> k1, a |-> Nothing k1 ]. Even though this subst has two
mappings, we surely don't want to add (k, k1) to the list of
GADT equalities -- that would be overly complex and would create
more untouchable variables than we need. So, when figuring out
which tyvars are GADT-like and which aren't (the fundamental
job of `choose`), we want to treat `k` as *not* GADT-like.
Instead, we wish to substitute in `a`'s kind, to get (a :: Maybe k1)
instead of (a :: Maybe k). This is the reason for dealing
with a substitution in here.

However, we do not *always* want to substitute. Consider

data H (a :: k) where
  MkH :: H Int

With explicit kind variables:

data H k (a :: k) where
  MkH :: H * Int

Here, we have a kind-indexed GADT. The subst in question is
[ k |-> *, a |-> Int ]. Now, we *don't* want to substitute in `a`'s
kind, because that would give a constructor with the type

MkH :: forall (k :: *) (a :: *). (k ~ *) -> (a ~ Int) -> H k a

The problem here is that a's kind is wrong -- it needs to be k, not *!
So, if the matching for a variable is anything but another bare variable,
we drop the mapping from the substitution before proceeding. This
was not an issue before kind-indexed GADTs because this case could
never happen.

************************************************************************
*                                                                      *
                Validity checking
*                                                                      *
************************************************************************

Validity checking is done once the mutually-recursive knot has been
tied, so we can look at things freely.
-}

checkValidTyCl :: TyCon -> TcM [TyCon]
-- The returned list is either a singleton (if valid)
-- or a list of "fake tycons" (if not); the fake tycons
-- include any implicits, like promoted data constructors
-- See Note [Recover from validity error]
checkValidTyCl :: TyCon -> TcM [TyCon]
checkValidTyCl TyCon
tc
  = SrcSpan -> TcM [TyCon] -> TcM [TyCon]
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (TyCon -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan TyCon
tc) (TcM [TyCon] -> TcM [TyCon]) -> TcM [TyCon] -> TcM [TyCon]
forall a b. (a -> b) -> a -> b
$
    TyCon -> TcM [TyCon] -> TcM [TyCon]
forall a. TyCon -> TcM a -> TcM a
addTyConCtxt TyCon
tc            (TcM [TyCon] -> TcM [TyCon]) -> TcM [TyCon] -> TcM [TyCon]
forall a b. (a -> b) -> a -> b
$
    TcM [TyCon] -> TcM [TyCon] -> TcM [TyCon]
forall r. TcRn r -> TcRn r -> TcRn r
recoverM TcM [TyCon]
recovery_code     (TcM [TyCon] -> TcM [TyCon]) -> TcM [TyCon] -> TcM [TyCon]
forall a b. (a -> b) -> a -> b
$
    do { String -> SDoc -> TcRn ()
traceTc String
"Starting validity for tycon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
       ; TyCon -> TcRn ()
checkValidTyCon TyCon
tc
       ; TyCon -> TcRn ()
checkTyConConsistentWithBoot TyCon
tc -- See Note [TyCon boot consistency checking]
       ; String -> SDoc -> TcRn ()
traceTc String
"Done validity for tycon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
       ; [TyCon] -> TcM [TyCon]
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return [TyCon
tc] }
  where
    recovery_code :: TcM [TyCon]
recovery_code -- See Note [Recover from validity error]
      = do { String -> SDoc -> TcRn ()
traceTc String
"Aborted validity for tycon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
           ; [TyCon] -> TcM [TyCon]
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ((TyCon -> TyCon) -> [TyCon] -> [TyCon]
forall a b. (a -> b) -> [a] -> [b]
map TyCon -> TyCon
mk_fake_tc ([TyCon] -> [TyCon]) -> [TyCon] -> [TyCon]
forall a b. (a -> b) -> a -> b
$
                     TyCon
tc TyCon -> [TyCon] -> [TyCon]
forall a. a -> [a] -> [a]
: TyCon -> [TyCon]
child_tycons TyCon
tc) }

    mk_fake_tc :: TyCon -> TyCon
mk_fake_tc TyCon
tc
      | TyCon -> Bool
isClassTyCon TyCon
tc = TyCon
tc   -- Ugh! Note [Recover from validity error]
      | Bool
otherwise       = TyCon -> TyCon
makeRecoveryTyCon TyCon
tc

    child_tycons :: TyCon -> [TyCon]
child_tycons TyCon
tc = TyCon -> [TyCon]
tyConATs TyCon
tc [TyCon] -> [TyCon] -> [TyCon]
forall a. [a] -> [a] -> [a]
++ (DataCon -> TyCon) -> [DataCon] -> [TyCon]
forall a b. (a -> b) -> [a] -> [b]
map DataCon -> TyCon
promoteDataCon (TyCon -> [DataCon]
tyConDataCons TyCon
tc)

{- Note [Recover from validity error]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We recover from a validity error in a type or class, which allows us
to report multiple validity errors. In the failure case we return a
TyCon of the right kind, but with no interesting behaviour
(makeRecoveryTyCon). Why?  Suppose we have
   type T a = Fun
where Fun is a type family of arity 1.  The RHS is invalid, but we
want to go on checking validity of subsequent type declarations.
So we replace T with an abstract TyCon which will do no harm.
See indexed-types/should_fail/BadSock and #10896

Some notes:

* We must make fakes for promoted DataCons too. Consider (#15215)
      data T a = MkT ...
      data S a = ...T...MkT....
  If there is an error in the definition of 'T' we add a "fake type
  constructor" to the type environment, so that we can continue to
  typecheck 'S'.  But we /were not/ adding a fake anything for 'MkT'
  and so there was an internal error when we met 'MkT' in the body of
  'S'.

  Similarly for associated types.

* Painfully, we *don't* want to do this for classes.
  Consider tcfail041:
     class (?x::Int) => C a where ...
     instance C Int
  The class is invalid because of the superclass constraint.  But
  we still want it to look like a /class/, else the instance bleats
  that the instance is mal-formed because it hasn't got a class in
  the head.

  This is really bogus; now we have in scope a Class that is invalid
  in some way, with unknown downstream consequences.  A better
  alternative might be to make a fake class TyCon.  A job for another day.

* Previously, we used implicitTyConThings to snaffle out the parts
  to add to the context. The problem is that this also grabs data con
  wrapper Ids. These could be filtered out. But, painfully, getting
  the wrapper Ids checks the DataConRep, and forcing the DataConRep
  can panic if there is a representation-polymorphic argument. This is #18534.
  We don't need the wrapper Ids here anyway. So the code just takes what
  it needs, via child_tycons.
-}

-------------------------
-- For data types declared with record syntax, we require
-- that each constructor that has a field 'f'
--      (a) has the same result type
--      (b) has the same type for 'f'
-- module alpha conversion of the quantified type variables
-- of the constructor.
--
-- Note that we allow existentials to match because the
-- fields can never meet. E.g
--      data T where
--        T1 { f1 :: b, f2 :: a, f3 ::Int } :: T
--        T2 { f1 :: c, f2 :: c, f3 ::Int } :: T
-- Here we do not complain about f1,f2 because they are existential

-- | Check that a 'TyCon' is consistent with the one in the hs-boot file,
-- if any.
--
-- See Note [TyCon boot consistency checking].
checkTyConConsistentWithBoot :: TyCon -> TcM ()
checkTyConConsistentWithBoot :: TyCon -> TcRn ()
checkTyConConsistentWithBoot TyCon
tc =
  do { gbl_env <- TcRnIf TcGblEnv TcLclEnv TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
     ; let name          = TyCon -> Name
tyConName TyCon
tc
           real_thing    = TyCon -> TyThing
ATyCon TyCon
tc
           boot_info     = TcGblEnv -> SelfBootInfo
tcg_self_boot TcGblEnv
gbl_env
           boot_type_env = case SelfBootInfo
boot_info of
             SelfBootInfo
NoSelfBoot            -> TypeEnv
emptyTypeEnv
             SelfBoot ModDetails
boot_details -> ModDetails -> TypeEnv
md_types ModDetails
boot_details
           m_boot_info   = TypeEnv -> Name -> Maybe TyThing
lookupTypeEnv TypeEnv
boot_type_env Name
name
     ; case m_boot_info of
         Maybe TyThing
Nothing         -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
         Just TyThing
boot_thing -> HsBootOrSig -> TyThing -> TyThing -> TcRn ()
checkBootDeclM HsBootOrSig
HsBoot TyThing
boot_thing TyThing
real_thing
     }

{- Note [TyCon boot consistency checking]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We want to throw an error when A.hs and A.hs-boot define a TyCon inconsistently,
e.g.

  -- A.hs-boot
  type D :: Type
  data D

  -- A.hs
  data D (k :: Type) = MkD

Here A.D and A[boot].D have different kinds, so we must error. In addition, we
must error eagerly, lest other parts of the compiler witness this inconsistency
(which was the subject of #16127). To achieve this, we call
checkTyConIsConsistentWithBoot in checkValidTyCl, which is called in
GHC.Tc.TyCl.tcTyClGroup.

Note that, when calling checkValidTyCl, we must extend the TyCon environment.
For example, we could end up comparing the RHS of two type synonym declarations
to check they are consistent, and these RHS might mention some of the TyCons we
are validity checking, so they need to be in the environment.
-}

checkValidTyCon :: TyCon -> TcM ()
checkValidTyCon :: TyCon -> TcRn ()
checkValidTyCon TyCon
tc
  | TyCon -> Bool
isPrimTyCon TyCon
tc   -- Happens when Haddock'ing GHC.Prim
  = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

  | TyCon -> Bool
forall thing. NamedThing thing => thing -> Bool
isWiredIn TyCon
tc     -- validity-checking wired-in tycons is a waste of
                     -- time. More importantly, a wired-in tycon might
                     -- violate assumptions. Example: (~) has a superclass
                     -- mentioning (~#), which is ill-kinded in source Haskell
  = String -> SDoc -> TcRn ()
traceTc String
"Skipping validity check for wired-in" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)

  | Bool
otherwise
  = do { String -> SDoc -> TcRn ()
traceTc String
"checkValidTyCon" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Maybe Class -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> Maybe Class
tyConClass_maybe TyCon
tc))
       ; if | Just Class
cl <- TyCon -> Maybe Class
tyConClass_maybe TyCon
tc
              -> Class -> TcRn ()
checkValidClass Class
cl

            | Just Type
syn_rhs <- TyCon -> Maybe Type
synTyConRhs_maybe TyCon
tc
              -> do { UserTypeCtxt -> Type -> TcRn ()
checkValidType UserTypeCtxt
syn_ctxt Type
syn_rhs
                    ; UserTypeCtxt -> Type -> TcRn ()
checkTySynRhs UserTypeCtxt
syn_ctxt Type
syn_rhs }

            | Just FamTyConFlav
fam_flav <- TyCon -> Maybe FamTyConFlav
famTyConFlav_maybe TyCon
tc
              -> case FamTyConFlav
fam_flav of
               { ClosedSynFamilyTyCon (Just CoAxiom Branched
ax)
                   -> TyCon -> TcRn () -> TcRn ()
forall a. TyCon -> TcM a -> TcM a
tcAddClosedTypeFamilyDeclCtxt TyCon
tc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                      CoAxiom Branched -> TcRn ()
checkValidCoAxiom CoAxiom Branched
ax
               ; ClosedSynFamilyTyCon Maybe (CoAxiom Branched)
Nothing   -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
               ; FamTyConFlav
AbstractClosedSynFamilyTyCon ->
                 do { hsBoot <- TcRnIf TcGblEnv TcLclEnv Bool
tcIsHsBootOrSig
                    ; checkTc hsBoot $ TcRnAbstractClosedTyFamDecl }
               ; DataFamilyTyCon {}           -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
               ; FamTyConFlav
OpenSynFamilyTyCon           -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
               ; BuiltInSynFamTyCon BuiltInSynFamily
_         -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return () }

             | Bool
otherwise -> do
               { -- Check the context on the data decl
                 String -> SDoc -> TcRn ()
traceTc String
"cvtc1" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)
               ; UserTypeCtxt -> ThetaType -> TcRn ()
checkValidTheta (Name -> UserTypeCtxt
DataTyCtxt Name
name) (TyCon -> ThetaType
tyConStupidTheta TyCon
tc)

               ; String -> SDoc -> TcRn ()
traceTc String
"cvtc2" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)

               ; dflags          <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
               ; existential_ok  <- xoptM LangExt.ExistentialQuantification
               ; gadt_ok         <- xoptM LangExt.GADTs
               ; let ex_ok = Bool
existential_ok Bool -> Bool -> Bool
|| Bool
gadt_ok
                     -- Data cons can have existential context
               ; mapM_ (checkValidDataCon dflags ex_ok tc) data_cons
               ; mapM_ (checkPartialRecordField data_cons) (tyConFieldLabels tc)

                -- Check that fields with the same name share a type
               ; mapM_ check_fields groups }}
  where
    syn_ctxt :: UserTypeCtxt
syn_ctxt  = Name -> UserTypeCtxt
TySynCtxt Name
name
    name :: Name
name      = TyCon -> Name
tyConName TyCon
tc
    data_cons :: [DataCon]
data_cons = TyCon -> [DataCon]
tyConDataCons TyCon
tc

    groups :: [NonEmpty (FieldLabel, DataCon)]
groups = ((FieldLabel, DataCon) -> (FieldLabel, DataCon) -> Ordering)
-> [(FieldLabel, DataCon)] -> [NonEmpty (FieldLabel, DataCon)]
forall a. (a -> a -> Ordering) -> [a] -> [NonEmpty a]
equivClasses (FieldLabel, DataCon) -> (FieldLabel, DataCon) -> Ordering
forall {b} {b}. (FieldLabel, b) -> (FieldLabel, b) -> Ordering
cmp_fld ((DataCon -> [(FieldLabel, DataCon)])
-> [DataCon] -> [(FieldLabel, DataCon)]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap DataCon -> [(FieldLabel, DataCon)]
get_fields [DataCon]
data_cons)
    -- This spot seems OK with non-determinism. cmp_fld is used only in equivClasses
    -- which produces equivalence classes.
    -- The order of these equivalence classes might conceivably (non-deterministically)
    -- depend on the result of this comparison, but that just affects the order in which
    -- fields are checked for compatibility. It will not affect the compiled binary.
    cmp_fld :: (FieldLabel, b) -> (FieldLabel, b) -> Ordering
cmp_fld (FieldLabel
f1,b
_) (FieldLabel
f2,b
_) = FieldLabelString -> FastString
field_label (FieldLabel -> FieldLabelString
flLabel FieldLabel
f1) FastString -> FastString -> Ordering
`uniqCompareFS` FieldLabelString -> FastString
field_label (FieldLabel -> FieldLabelString
flLabel FieldLabel
f2)
    get_fields :: DataCon -> [(FieldLabel, DataCon)]
get_fields DataCon
con = DataCon -> [FieldLabel]
dataConFieldLabels DataCon
con [FieldLabel] -> [DataCon] -> [(FieldLabel, DataCon)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` DataCon -> [DataCon]
forall a. a -> [a]
repeat DataCon
con
        -- dataConFieldLabels may return the empty list, which is fine

    -- See Note [GADT record selectors] in GHC.Tc.TyCl.Utils
    -- We must check (a) that the named field has the same
    --                   type in each constructor
    --               (b) that those constructors have the same result type
    --
    -- However, the constructors may have differently named type variable
    -- and (worse) we don't know how the correspond to each other.  E.g.
    --     C1 :: forall a b. { f :: a, g :: b } -> T a b
    --     C2 :: forall d c. { f :: c, g :: c } -> T c d
    --
    -- So what we do is to ust Unify.tcMatchTys to compare the first candidate's
    -- result type against other candidates' types BOTH WAYS ROUND.
    -- If they magically agrees, take the substitution and
    -- apply them to the latter ones, and see if they match perfectly.
    check_fields :: NonEmpty (FieldLabel, DataCon) -> TcRn ()
check_fields ((FieldLabel
label, DataCon
con1) :| [(FieldLabel, DataCon)]
other_fields)
        -- These fields all have the same name, but are from
        -- different constructors in the data type
        = TcRn () -> TcRn () -> TcRn ()
forall r. TcRn r -> TcRn r -> TcRn r
recoverM (() -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ ((FieldLabel, DataCon) -> TcRn ())
-> [(FieldLabel, DataCon)] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (FieldLabel, DataCon) -> TcRn ()
checkOne [(FieldLabel, DataCon)]
other_fields
                -- Check that all the fields in the group have the same type
                -- NB: this check assumes that all the constructors of a given
                -- data type use the same type variables
        where
        res1 :: Type
res1 = DataCon -> Type
dataConOrigResTy DataCon
con1
        fty1 :: Type
fty1 = DataCon -> FieldLabelString -> Type
dataConFieldType DataCon
con1 FieldLabelString
lbl
        lbl :: FieldLabelString
lbl = FieldLabel -> FieldLabelString
flLabel FieldLabel
label

        checkOne :: (FieldLabel, DataCon) -> TcRn ()
checkOne (FieldLabel
_, DataCon
con2)    -- Do it both ways to ensure they are structurally identical
            = do { FieldLabelString
-> DataCon -> DataCon -> Type -> Type -> Type -> Type -> TcRn ()
checkFieldCompat FieldLabelString
lbl DataCon
con1 DataCon
con2 Type
res1 Type
res2 Type
fty1 Type
fty2
                 ; FieldLabelString
-> DataCon -> DataCon -> Type -> Type -> Type -> Type -> TcRn ()
checkFieldCompat FieldLabelString
lbl DataCon
con2 DataCon
con1 Type
res2 Type
res1 Type
fty2 Type
fty1 }
            where
                res2 :: Type
res2 = DataCon -> Type
dataConOrigResTy DataCon
con2
                fty2 :: Type
fty2 = DataCon -> FieldLabelString -> Type
dataConFieldType DataCon
con2 FieldLabelString
lbl

checkPartialRecordField :: [DataCon] -> FieldLabel -> TcM ()
-- Checks the partial record field selector, and warns.
-- See Note [Checking partial record field]
checkPartialRecordField :: [DataCon] -> FieldLabel -> TcRn ()
checkPartialRecordField [DataCon]
all_cons FieldLabel
fld
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
      Bool -> TcRnMessage -> TcRn ()
warnIf (Bool -> Bool
not Bool
is_exhaustive Bool -> Bool -> Bool
&& Bool -> Bool
not (OccName -> Bool
startsWithUnderscore OccName
occ_name))
             (FieldLabel -> TcRnMessage
TcRnPartialFieldSelector FieldLabel
fld)
  where
    sel :: Name
sel = FieldLabel -> Name
flSelector FieldLabel
fld
    loc :: SrcSpan
loc = Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
sel
    occ_name :: OccName
occ_name = Name -> OccName
nameOccName Name
sel

    ([DataCon]
cons_with_field, [DataCon]
cons_without_field) = (DataCon -> Bool) -> [DataCon] -> ([DataCon], [DataCon])
forall a. (a -> Bool) -> [a] -> ([a], [a])
partition DataCon -> Bool
has_field [DataCon]
all_cons
    has_field :: DataCon -> Bool
has_field DataCon
con = FieldLabel
fld FieldLabel -> [FieldLabel] -> Bool
forall a. Eq a => a -> [a] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` (DataCon -> [FieldLabel]
dataConFieldLabels DataCon
con)
    is_exhaustive :: Bool
is_exhaustive = (DataCon -> Bool) -> [DataCon] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (ThetaType -> DataCon -> Bool
dataConCannotMatch ThetaType
inst_tys) [DataCon]
cons_without_field

    con1 :: DataCon
con1 = Bool -> DataCon -> DataCon
forall a. HasCallStack => Bool -> a -> a
assert (Bool -> Bool
not ([DataCon] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [DataCon]
cons_with_field)) (DataCon -> DataCon) -> DataCon -> DataCon
forall a b. (a -> b) -> a -> b
$ [DataCon] -> DataCon
forall a. HasCallStack => [a] -> a
head [DataCon]
cons_with_field
    inst_tys :: ThetaType
inst_tys = DataCon -> ThetaType
dataConResRepTyArgs DataCon
con1

checkFieldCompat :: FieldLabelString -> DataCon -> DataCon
                 -> Type -> Type -> Type -> Type -> TcM ()
checkFieldCompat :: FieldLabelString
-> DataCon -> DataCon -> Type -> Type -> Type -> Type -> TcRn ()
checkFieldCompat FieldLabelString
fld DataCon
con1 DataCon
con2 Type
res1 Type
res2 Type
fty1 Type
fty2
  = do  { Bool -> TcRnMessage -> TcRn ()
checkTc (Maybe Subst -> Bool
forall a. Maybe a -> Bool
isJust Maybe Subst
mb_subst1) (DataCon -> DataCon -> FieldLabelString -> TcRnMessage
TcRnCommonFieldResultTypeMismatch DataCon
con1 DataCon
con2 FieldLabelString
fld)
        ; Bool -> TcRnMessage -> TcRn ()
checkTc (Maybe Subst -> Bool
forall a. Maybe a -> Bool
isJust Maybe Subst
mb_subst2) (DataCon -> DataCon -> FieldLabelString -> TcRnMessage
TcRnCommonFieldTypeMismatch DataCon
con1 DataCon
con2 FieldLabelString
fld) }
  where
    mb_subst1 :: Maybe Subst
mb_subst1 = Type -> Type -> Maybe Subst
tcMatchTy Type
res1 Type
res2
    mb_subst2 :: Maybe Subst
mb_subst2 = Subst -> Type -> Type -> Maybe Subst
tcMatchTyX (String -> Maybe Subst -> Subst
forall a. HasCallStack => String -> Maybe a -> a
expectJust String
"checkFieldCompat" Maybe Subst
mb_subst1) Type
fty1 Type
fty2

-------------------------------
checkValidDataCon :: DynFlags -> Bool -> TyCon -> DataCon -> TcM ()
checkValidDataCon :: DynFlags -> Bool -> TyCon -> DataCon -> TcRn ()
checkValidDataCon DynFlags
dflags Bool
existential_ok TyCon
tc DataCon
con
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
con_loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (NonEmpty (LocatedN Name) -> SDoc
dataConCtxt (LocatedN Name -> NonEmpty (LocatedN Name)
forall a. a -> NonEmpty a
NE.singleton (SrcSpanAnnN -> Name -> LocatedN Name
forall l e. l -> e -> GenLocated l e
L (SrcSpan -> SrcSpanAnnN
forall e. HasAnnotation e => SrcSpan -> e
noAnnSrcSpan SrcSpan
con_loc) Name
con_name))) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    do  { let tc_tvs :: [Var]
tc_tvs      = TyCon -> [Var]
tyConTyVars TyCon
tc
              res_ty_tmpl :: Type
res_ty_tmpl = TyCon -> ThetaType -> Type
mkFamilyTyConApp TyCon
tc ([Var] -> ThetaType
mkTyVarTys [Var]
tc_tvs)
              arg_tys :: [Scaled Type]
arg_tys     = DataCon -> [Scaled Type]
dataConOrigArgTys DataCon
con
              orig_res_ty :: Type
orig_res_ty = DataCon -> Type
dataConOrigResTy  DataCon
con

        ; String -> SDoc -> TcRn ()
traceTc String
"checkValidDataCon" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
              [ DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
con, TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc, [Var] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Var]
tc_tvs
              , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
res_ty_tmpl SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
res_ty_tmpl)
              , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
orig_res_ty SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
orig_res_ty)])


        -- Check that the return type of the data constructor
        -- matches the type constructor; eg reject this:
        --   data T a where { MkT :: Bogus a }
        -- It's important to do this first:
        --  see Note [rejigConRes]
        --  and c.f. Note [Check role annotations in a second pass]

        -- Check that the return type of the data constructor is an instance
        -- of the header of the header of data decl.  This checks for
        --      data T a where { MkT :: S a }
        --      data instance D [a] where { MkD :: D (Maybe b) }
        -- see Note [GADT return types]
        ; Bool -> TcRnMessage -> TcRn ()
checkTc (Maybe Subst -> Bool
forall a. Maybe a -> Bool
isJust (Type -> Type -> Maybe Subst
tcMatchTyKi Type
res_ty_tmpl Type
orig_res_ty))
                  (DataCon -> Type -> TcRnMessage
TcRnDataConParentTypeMismatch DataCon
con Type
res_ty_tmpl)
            -- Note that checkTc aborts if it finds an error. This is
            -- critical to avoid panicking when we call dataConDisplayType
            -- on an un-rejiggable datacon!
            -- Also NB that we match the *kind* as well as the *type* (#18357)
            -- However, if the kind is the only thing that doesn't match, the
            -- error message is terrible.  E.g. test T18357b
            --    type family Star where Star = Type
            --    newtype T :: Type where MkT :: Int -> (T :: Star)

        ; String -> SDoc -> TcRn ()
traceTc String
"checkValidDataCon 2" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
data_con_display_type)

          -- Check that the result type is a *monotype*
          --  e.g. reject this:   MkT :: T (forall a. a->a)
          -- Reason: it's really the argument of an equality constraint
        ; Type -> TcRn ()
checkValidMonoType Type
orig_res_ty
        ; Type -> TcRn ()
checkEscapingKind (DataCon -> Type
dataConWrapperType DataCon
con)

        -- For /data/ types check that each argument has a fixed runtime rep
        -- If we are dealing with a /newtype/, we allow representation
        -- polymorphism regardless of whether or not UnliftedNewtypes
        -- is enabled. A later check in checkNewDataCon handles this,
        -- producing a better error message than checkTypeHasFixedRuntimeRep would.
        ; let check_rr :: Type -> TcRn ()
check_rr = FixedRuntimeRepProvenance -> Type -> TcRn ()
checkTypeHasFixedRuntimeRep FixedRuntimeRepProvenance
FixedRuntimeRepDataConField
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (TyCon -> Bool
isNewTyCon TyCon
tc) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          TcRn () -> TcRn ()
forall r. TcM r -> TcM r
checkNoErrs            (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          (Scaled Type -> TcRn ()) -> [Scaled Type] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Type -> TcRn ()
check_rr (Type -> TcRn ())
-> (Scaled Type -> Type) -> Scaled Type -> TcRn ()
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Scaled Type -> Type
forall a. Scaled a -> a
scaledThing) [Scaled Type]
arg_tys
            -- The checkNoErrs is to prevent a panic in isVanillaDataCon
            -- (called a a few lines down), which can fall over if there is a
            -- bang on a representation-polymorphic argument. This is #18534,
            -- typecheck/should_fail/T18534

          -- Extra checks for newtype data constructors. Importantly, these
          -- checks /must/ come before the call to checkValidType below. This
          -- is because checkValidType invokes the constraint solver, and
          -- invoking the solver on an ill formed newtype constructor can
          -- confuse GHC to the point of panicking. See #17955 for an example.
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (TyCon -> Bool
isNewTyCon TyCon
tc) (DataCon -> TcRn ()
checkNewDataCon DataCon
con)

          -- Check all argument types for validity
        ; UserTypeCtxt -> Type -> TcRn ()
checkValidType UserTypeCtxt
ctxt Type
data_con_display_type

          -- Check that existentials are allowed if they are used
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Bool
existential_ok Bool -> Bool -> Bool
|| DataCon -> Bool
isVanillaDataCon DataCon
con) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                  TcRnMessage -> TcRn ()
addErrTc (DataCon -> TcRnMessage
TcRnExistentialQuantificationDisabled DataCon
con)

          -- Check that the only constraints in signatures of constructors
          -- in a "type data" declaration are equality constraints.
          -- See Note [Type data declarations] in GHC.Rename.Module,
          -- restriction (R4).
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (DataCon -> Bool
isTypeDataCon DataCon
con) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          Bool -> TcRnMessage -> TcRn ()
checkTc ((Type -> Bool) -> ThetaType -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all Type -> Bool
isEqPred (DataCon -> ThetaType
dataConOtherTheta DataCon
con))
                  (Type -> TcRnMessage
TcRnConstraintInKind (DataCon -> Type
dataConRepType DataCon
con))

        ; hsc_env <- IOEnv (Env TcGblEnv TcLclEnv) HscEnv
forall gbl lcl. TcRnIf gbl lcl HscEnv
getTopEnv
        ; let check_bang :: Type -> HsSrcBang -> HsImplBang -> Int -> TcM ()
              check_bang Type
orig_arg_ty HsSrcBang
bang HsImplBang
rep_bang Int
n
               | HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcLazy <- HsSrcBang
bang
               , Bool -> Bool
not (BangOpts -> Bool
bang_opt_strict_data BangOpts
bang_opts)
               = TcRnMessage -> TcRn ()
addErrTc (Int -> BadFieldAnnotationReason -> TcRnMessage
bad_bang Int
n BadFieldAnnotationReason
LazyFieldsDisabled)

               -- Warn about UNPACK without "!"
               -- e.g.   data T = MkT {-# UNPACK #-} Int
               | HsSrcBang SourceText
_ SrcUnpackedness
want_unpack SrcStrictness
strict_mark <- HsSrcBang
bang
               , SrcUnpackedness -> Bool
isSrcUnpacked SrcUnpackedness
want_unpack, Bool -> Bool
not (SrcStrictness -> Bool
is_strict SrcStrictness
strict_mark)
               , Bool -> Bool
not (HasDebugCallStack => Type -> Bool
Type -> Bool
isUnliftedType Type
orig_arg_ty)
               = TcRnMessage -> TcRn ()
addDiagnosticTc (Int -> BadFieldAnnotationReason -> TcRnMessage
bad_bang Int
n BadFieldAnnotationReason
UnpackWithoutStrictness)

               -- Warn about a redundant ! on an unlifted type
               -- e.g.   data T = MkT !Int#
               | HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcStrict <- HsSrcBang
bang
               , HasDebugCallStack => Type -> Bool
Type -> Bool
isUnliftedType Type
orig_arg_ty
               = TcRnMessage -> TcRn ()
addDiagnosticTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Type -> TcRnMessage
TcRnBangOnUnliftedType Type
orig_arg_ty

               -- Warn about a ~ on an unlifted type (#21951)
               -- e.g.   data T = MkT ~Int#
               | HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcLazy <- HsSrcBang
bang
               , HasDebugCallStack => Type -> Bool
Type -> Bool
isUnliftedType Type
orig_arg_ty
               = TcRnMessage -> TcRn ()
addDiagnosticTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Type -> TcRnMessage
TcRnLazyBangOnUnliftedType Type
orig_arg_ty

               -- Warn about unusable UNPACK pragmas
               -- e.g.   data T a = MkT {-# UNPACK #-} !a      -- Can't unpack
               | HsSrcBang SourceText
_ SrcUnpackedness
want_unpack SrcStrictness
_ <- HsSrcBang
bang

               -- See Note [Detecting useless UNPACK pragmas] in GHC.Core.DataCon.
               , SrcUnpackedness -> Bool
isSrcUnpacked SrcUnpackedness
want_unpack  -- this means the user wrote {-# UNPACK #-}
               , case HsImplBang
rep_bang of { HsUnpack {} -> Bool
False; HsStrict Bool
True -> Bool
False; HsImplBang
_ -> Bool
True }

               -- When typechecking an indefinite package in Backpack, we
               -- may attempt to UNPACK an abstract type.  The test here will
               -- conclude that this is unusable, but it might become usable
               -- when we actually fill in the abstract type.  As such, don't
               -- warn in this case (it gives users the wrong idea about whether
               -- or not UNPACK on abstract types is supported; it is!)
               , HomeUnit -> Bool
forall u. GenHomeUnit u -> Bool
isHomeUnitDefinite (HscEnv -> HomeUnit
hsc_home_unit HscEnv
hsc_env)
               = TcRnMessage -> TcRn ()
addDiagnosticTc (Int -> BadFieldAnnotationReason -> TcRnMessage
bad_bang Int
n BadFieldAnnotationReason
BackpackUnpackAbstractType)

               | Bool
otherwise
               = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

        ; void $ zipWith4M check_bang (map scaledThing $ dataConOrigArgTys con)
          (dataConSrcBangs con) (dataConImplBangs con) [1..]

          -- Check the dcUserTyVarBinders invariant
          -- See Note [DataCon user type variable binders] in GHC.Core.DataCon
          -- checked here because we sometimes build invalid DataCons before
          -- erroring above here
        ; when debugIsOn $ whenNoErrs $
          massertPpr (checkDataConTyVars con) $
          ppr con $$  ppr (dataConFullSig con) $$ ppr (dataConUserTyVars con)

        ; traceTc "Done validity of data con" $
          vcat [ ppr con
               , text "Datacon wrapper type:" <+> ppr (dataConWrapperType con)
               , text "Datacon rep type:" <+> ppr (dataConRepType con)
               , text "Datacon display type:" <+> ppr data_con_display_type
               , text "Rep typcon binders:" <+> ppr (tyConBinders (dataConTyCon con))
               , case tyConFamInst_maybe (dataConTyCon con) of
                   Maybe (TyCon, ThetaType)
Nothing -> String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"not family"
                   Just (TyCon
f, ThetaType
_) -> [TyConBinder] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [TyConBinder]
tyConBinders TyCon
f) ]
    }
  where
    bang_opts :: BangOpts
bang_opts = DynFlags -> BangOpts
initBangOpts DynFlags
dflags
    con_name :: Name
con_name  = DataCon -> Name
dataConName DataCon
con
    con_loc :: SrcSpan
con_loc   = Name -> SrcSpan
nameSrcSpan Name
con_name
    ctxt :: UserTypeCtxt
ctxt      = Name -> UserTypeCtxt
ConArgCtxt Name
con_name
    is_strict :: SrcStrictness -> Bool
is_strict = \case
      SrcStrictness
NoSrcStrict -> BangOpts -> Bool
bang_opt_strict_data BangOpts
bang_opts
      SrcStrictness
bang        -> SrcStrictness -> Bool
isSrcStrict SrcStrictness
bang

    bad_bang :: Int -> BadFieldAnnotationReason -> TcRnMessage
bad_bang Int
n
      = Int -> DataCon -> BadFieldAnnotationReason -> TcRnMessage
TcRnBadFieldAnnotation Int
n DataCon
con

    show_linear_types :: Bool
show_linear_types     = Extension -> DynFlags -> Bool
xopt Extension
LangExt.LinearTypes DynFlags
dflags
    data_con_display_type :: Type
data_con_display_type = Bool -> DataCon -> Type
dataConDisplayType Bool
show_linear_types DataCon
con

-------------------------------
checkNewDataCon :: DataCon -> TcM ()
-- Further checks for the data constructor of a newtype
-- You might wonder if we need to check for an unlifted newtype
-- without -XUnliftedNewtypes, such as
--   newtype C = MkC Int#
-- But they are caught earlier, by GHC.Tc.Gen.HsType.checkDataKindSig
checkNewDataCon :: DataCon -> TcRn ()
checkNewDataCon DataCon
con
  = do  { show_linear_types <- Extension -> DynFlags -> Bool
xopt Extension
LangExt.LinearTypes (DynFlags -> Bool)
-> IOEnv (Env TcGblEnv TcLclEnv) DynFlags
-> TcRnIf TcGblEnv TcLclEnv Bool
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
        ; checkNoErrs $
          -- Fail here if the newtype is invalid: subsequent code in
          -- checkValidDataCon can fall over if it comes across an invalid newtype.
     do { case arg_tys of
            [Scaled Type
arg_mult Type
_] ->
              Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Type -> Bool
ok_mult Type
arg_mult) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
              TcRnMessage -> TcRn ()
addErrTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
              DataCon -> Bool -> IllegalNewtypeReason -> TcRnMessage
TcRnIllegalNewtype DataCon
con Bool
show_linear_types IllegalNewtypeReason
IsNonLinear
            [Scaled Type]
_ ->
              TcRnMessage -> TcRn ()
addErrTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
              DataCon -> Bool -> IllegalNewtypeReason -> TcRnMessage
TcRnIllegalNewtype DataCon
con Bool
show_linear_types (Int -> IllegalNewtypeReason
DoesNotHaveSingleField (Int -> IllegalNewtypeReason) -> Int -> IllegalNewtypeReason
forall a b. (a -> b) -> a -> b
$ [Scaled Type] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Scaled Type]
arg_tys)

          -- Add an error if the newtype is a GADt or has existentials.
          --
          -- If the newtype is a GADT, the GADT error is enough;
          -- we don't need to *also* complain about existentials.
        ; if not (null eq_spec)
          then addErrTc $ TcRnIllegalNewtype con show_linear_types IsGADT
          else unless (null ex_tvs) $
               addErrTc $
               TcRnIllegalNewtype con show_linear_types HasExistentialTyVar

        ; unless (null theta) $
          addErrTc $
          TcRnIllegalNewtype con show_linear_types HasConstructorContext

        ; unless (all ok_bang (dataConSrcBangs con)) $
          addErrTc $
          TcRnIllegalNewtype con show_linear_types HasStrictnessAnnotation } }
  where

    ([Var]
_univ_tvs, [Var]
ex_tvs, [EqSpec]
eq_spec, ThetaType
theta, [Scaled Type]
arg_tys, Type
_res_ty)
      = DataCon -> ([Var], [Var], [EqSpec], ThetaType, [Scaled Type], Type)
dataConFullSig DataCon
con

    ok_bang :: HsSrcBang -> Bool
ok_bang (HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcStrict) = Bool
False
    ok_bang (HsSrcBang SourceText
_ SrcUnpackedness
_ SrcStrictness
SrcLazy)   = Bool
False
    ok_bang HsSrcBang
_                         = Bool
True

    ok_mult :: Type -> Bool
ok_mult Type
OneTy = Bool
True
    ok_mult Type
_     = Bool
False

-------------------------------
checkValidClass :: Class -> TcM ()
checkValidClass :: Class -> TcRn ()
checkValidClass Class
cls
  = do  { constrained_class_methods <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.ConstrainedClassMethods
        ; multi_param_type_classes  <- xoptM LangExt.MultiParamTypeClasses
        ; nullary_type_classes      <- xoptM LangExt.NullaryTypeClasses
        ; fundep_classes            <- xoptM LangExt.FunctionalDependencies
        ; undecidable_super_classes <- xoptM LangExt.UndecidableSuperClasses

        -- Check that the class is unary, unless multiparameter type classes
        -- are enabled; also recognize deprecated nullary type classes
        -- extension (subsumed by multiparameter type classes, #8993)
        ; checkTc (multi_param_type_classes || cls_arity == 1 ||
                    (nullary_type_classes && cls_arity == 0))
                  (TcRnClassExtensionDisabled cls (MultiParamDisabled cls_arity))
        ; unless (fundep_classes || null fundeps) $
                 addErrTc (TcRnClassExtensionDisabled cls FunDepsDisabled)

        -- Check the super-classes
        ; checkValidTheta (ClassSCCtxt (className cls)) theta

          -- Now check for cyclic superclasses
          -- If there are superclass cycles, checkClassCycleErrs bails.
        ; unless undecidable_super_classes $
          case checkClassCycles cls of
             Just SuperclassCycle
err -> SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Class -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Class
cls) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                         TcRnMessage -> TcRn ()
addErrTc (SuperclassCycle -> TcRnMessage
TcRnSuperclassCycle SuperclassCycle
err)
             Maybe SuperclassCycle
Nothing  -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

        -- Check the class operations.
        -- But only if there have been no earlier errors
        -- See Note [Abort when superclass cycle is detected]
        ; whenNoErrs $
          mapM_ (check_op constrained_class_methods) op_stuff

        -- Check the associated type defaults are well-formed and instantiated
        ; mapM_ check_at at_stuff  }
  where
    ([Var]
tyvars, [([Var], [Var])]
fundeps, ThetaType
theta, [Var]
_, [ClassATItem]
at_stuff, [(Var, DefMethInfo)]
op_stuff) = Class
-> ([Var], [([Var], [Var])], ThetaType, [Var], [ClassATItem],
    [(Var, DefMethInfo)])
classExtraBigSig Class
cls
    cls_arity :: Int
cls_arity = [Var] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (TyCon -> [Var]
tyConVisibleTyVars (Class -> TyCon
classTyCon Class
cls))
       -- Ignore invisible variables
    cls_tv_set :: VarSet
cls_tv_set = [Var] -> VarSet
mkVarSet [Var]
tyvars

    check_op :: Bool -> (Var, DefMethInfo) -> TcRn ()
check_op Bool
constrained_class_methods (Var
sel_id, DefMethInfo
dm)
      = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Var -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Var
sel_id) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        SDoc -> TcRn () -> TcRn ()
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (Var -> Type -> SDoc
classOpCtxt Var
sel_id Type
op_ty) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ do
        { String -> SDoc -> TcRn ()
traceTc String
"class op type" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
op_ty)
        ; UserTypeCtxt -> Type -> TcRn ()
checkValidType UserTypeCtxt
ctxt Type
op_ty
                -- This implements the ambiguity check, among other things
                -- Example: tc223
                --   class Error e => Game b mv e | b -> mv e where
                --      newBoard :: MonadState b m => m ()
                -- Here, MonadState has a fundep m->b, so newBoard is fine

        -- NB: we don't check that the class method is not representation-polymorphic here,
        -- as GHC.TcGen.TyCl.tcClassSigType already includes a subtype check that guarantees
        -- typeclass methods always have kind 'Type'.
        --
        -- Test case: rep-poly/RepPolyClassMethod.

        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless Bool
constrained_class_methods (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          (Type -> TcRn ()) -> ThetaType -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ Type -> TcRn ()
check_constraint ThetaType
op_theta

        ; UserTypeCtxt -> Var -> Type -> Type -> DefMethInfo -> TcRn ()
check_dm UserTypeCtxt
ctxt Var
sel_id Type
cls_pred Type
tau2 DefMethInfo
dm
        }
        where
          ctxt :: UserTypeCtxt
ctxt    = Name -> ReportRedundantConstraints -> UserTypeCtxt
FunSigCtxt Name
op_name (SrcSpan -> ReportRedundantConstraints
WantRRC (Class -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Class
cls)) -- Report redundant class constraints
          op_name :: Name
op_name = Var -> Name
idName Var
sel_id
          op_ty :: Type
op_ty   = Var -> Type
idType Var
sel_id
          ([Var]
_,Type
cls_pred,Type
tau1) = Type -> ([Var], Type, Type)
tcSplitMethodTy Type
op_ty
          -- See Note [Splitting nested sigma types in class type signatures]
          ([Var]
_,ThetaType
op_theta,Type
tau2) = Type -> ([Var], ThetaType, Type)
tcSplitNestedSigmaTys Type
tau1

          check_constraint :: TcPredType -> TcM ()
          check_constraint :: Type -> TcRn ()
check_constraint Type
pred -- See Note [Class method constraints]
            = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Bool -> Bool
not (VarSet -> Bool
isEmptyVarSet VarSet
pred_tvs) Bool -> Bool -> Bool
&&
                    VarSet
pred_tvs VarSet -> VarSet -> Bool
`subVarSet` VarSet
cls_tv_set)
                   (TcRnMessage -> TcRn ()
addErrTc (Class -> DisabledClassExtension -> TcRnMessage
TcRnClassExtensionDisabled Class
cls (Var -> Type -> DisabledClassExtension
ConstrainedClassMethodsDisabled Var
sel_id Type
pred)))
            where
              pred_tvs :: VarSet
pred_tvs = Type -> VarSet
tyCoVarsOfType Type
pred

    check_at :: ClassATItem -> TcRn ()
check_at (ATI TyCon
fam_tc Maybe (Type, TyFamEqnValidityInfo)
m_dflt_rhs)
      = do { String -> SDoc -> TcRn ()
traceTc String
"ati" (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
fam_tc SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [Var] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Var]
tyvars SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ [Var] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Var]
fam_tvs)
           ; Bool -> TcRnMessage -> TcRn ()
checkTc (Int
cls_arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0 Bool -> Bool -> Bool
|| (Var -> Bool) -> [Var] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any (Var -> VarSet -> Bool
`elemVarSet` VarSet
cls_tv_set) [Var]
fam_tvs) (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
              IllegalInstanceReason -> TcRnMessage
TcRnIllegalInstance (IllegalInstanceReason -> TcRnMessage)
-> IllegalInstanceReason -> TcRnMessage
forall a b. (a -> b) -> a -> b
$ IllegalFamilyInstanceReason -> IllegalInstanceReason
IllegalFamilyInstance (IllegalFamilyInstanceReason -> IllegalInstanceReason)
-> IllegalFamilyInstanceReason -> IllegalInstanceReason
forall a b. (a -> b) -> a -> b
$
                InvalidAssoc -> IllegalFamilyInstanceReason
InvalidAssoc (InvalidAssoc -> IllegalFamilyInstanceReason)
-> InvalidAssoc -> IllegalFamilyInstanceReason
forall a b. (a -> b) -> a -> b
$ InvalidAssocInstance -> InvalidAssoc
InvalidAssocInstance (InvalidAssocInstance -> InvalidAssoc)
-> InvalidAssocInstance -> InvalidAssoc
forall a b. (a -> b) -> a -> b
$
                Class -> TyCon -> InvalidAssocInstance
AssocNoClassTyVar Class
cls TyCon
fam_tc
                        -- Check that the associated type mentions at least
                        -- one of the class type variables
                        -- The check is disabled for nullary type classes,
                        -- since there is no possible ambiguity (#10020)

             -- Check that any default declarations for associated types are valid
           ; Maybe (Type, TyFamEqnValidityInfo)
-> ((Type, TyFamEqnValidityInfo) -> TcRn ()) -> TcRn ()
forall (m :: * -> *) a. Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust Maybe (Type, TyFamEqnValidityInfo)
m_dflt_rhs (((Type, TyFamEqnValidityInfo) -> TcRn ()) -> TcRn ())
-> ((Type, TyFamEqnValidityInfo) -> TcRn ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$ \ (Type
_, TyFamEqnValidityInfo
at_validity_info) ->
             case TyFamEqnValidityInfo
at_validity_info of
               TyFamEqnValidityInfo
NoVI -> () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (f :: * -> *) a. Applicative f => a -> f a
pure ()
               VI { vi_loc :: TyFamEqnValidityInfo -> SrcSpan
vi_loc          = SrcSpan
loc
                  , vi_qtvs :: TyFamEqnValidityInfo -> [Var]
vi_qtvs         = [Var]
qtvs
                  , vi_non_user_tvs :: TyFamEqnValidityInfo -> VarSet
vi_non_user_tvs = VarSet
non_user_tvs
                  , vi_pats :: TyFamEqnValidityInfo -> ThetaType
vi_pats         = ThetaType
pats
                  , vi_rhs :: TyFamEqnValidityInfo -> Type
vi_rhs          = Type
orig_rhs } ->
                 SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                 SDoc -> Name -> TcRn () -> TcRn ()
forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"default type instance") (TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
fam_tc) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                 do { TyCon -> ThetaType -> TcRn ()
checkValidAssocTyFamDeflt TyCon
fam_tc ThetaType
pats
                    ; TyCon -> [Var] -> VarSet -> ThetaType -> Type -> TcRn ()
checkFamPatBinders TyCon
fam_tc [Var]
qtvs VarSet
non_user_tvs ThetaType
pats Type
orig_rhs
                    ; TyCon -> ThetaType -> Type -> TcRn ()
checkValidTyFamEqn TyCon
fam_tc ThetaType
pats Type
orig_rhs }}
        where
          fam_tvs :: [Var]
fam_tvs = TyCon -> [Var]
tyConTyVars TyCon
fam_tc

    check_dm :: UserTypeCtxt -> Id -> PredType -> Type -> DefMethInfo -> TcM ()
    -- Check validity of the /top-level/ generic-default type
    -- E.g for   class C a where
    --             default op :: forall b. (a~b) => blah
    -- we do not want to do an ambiguity check on a type with
    -- a free TyVar 'a' (#11608).  See TcType
    -- Note [TyVars and TcTyVars during type checking] in GHC.Tc.Utils.TcType
    -- Hence the mkDefaultMethodType to close the type.
    check_dm :: UserTypeCtxt -> Var -> Type -> Type -> DefMethInfo -> TcRn ()
check_dm UserTypeCtxt
ctxt Var
sel_id Type
vanilla_cls_pred Type
vanilla_tau
             (Just (Name
dm_name, dm_spec :: DefMethSpec Type
dm_spec@(GenericDM Type
dm_ty)))
      = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
dm_name) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ do
            -- We have carefully set the SrcSpan on the generic
            -- default-method Name to be that of the generic
            -- default type signature

          -- First, we check that the method's default type signature
          -- aligns with the non-default type signature.
          -- See Note [Default method type signatures must align]
          let cls_pred :: Type
cls_pred = Class -> ThetaType -> Type
mkClassPred Class
cls (ThetaType -> Type) -> ThetaType -> Type
forall a b. (a -> b) -> a -> b
$ [Var] -> ThetaType
mkTyVarTys ([Var] -> ThetaType) -> [Var] -> ThetaType
forall a b. (a -> b) -> a -> b
$ Class -> [Var]
classTyVars Class
cls
              -- Note that the second field of this tuple contains the context
              -- of the default type signature, making it apparent that we
              -- ignore method contexts completely when validity-checking
              -- default type signatures. See the end of
              -- Note [Default method type signatures must align]
              -- to learn why this is OK.
              --
              -- See also
              -- Note [Splitting nested sigma types in class type signatures]
              -- for an explanation of why we don't use tcSplitSigmaTy here.
              ([Var]
_, ThetaType
_, Type
dm_tau) = Type -> ([Var], ThetaType, Type)
tcSplitNestedSigmaTys Type
dm_ty

              -- Given this class definition:
              --
              --  class C a b where
              --    op         :: forall p q. (Ord a, D p q)
              --               => a -> b -> p -> (a, b)
              --    default op :: forall r s. E r
              --               => a -> b -> s -> (a, b)
              --
              -- We want to match up two types of the form:
              --
              --   Vanilla type sig: C aa bb => aa -> bb -> p -> (aa, bb)
              --   Default type sig: C a  b  => a  -> b  -> s -> (a,  b)
              --
              -- Notice that the two type signatures can be quantified over
              -- different class type variables! Therefore, it's important that
              -- we include the class predicate parts to match up a with aa and
              -- b with bb.
              vanilla_phi_ty :: Type
vanilla_phi_ty = ThetaType -> Type -> Type
HasDebugCallStack => ThetaType -> Type -> Type
mkPhiTy [Type
vanilla_cls_pred] Type
vanilla_tau
              dm_phi_ty :: Type
dm_phi_ty      = ThetaType -> Type -> Type
HasDebugCallStack => ThetaType -> Type -> Type
mkPhiTy [Type
cls_pred] Type
dm_tau

          String -> SDoc -> TcRn ()
traceTc String
"check_dm" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
              [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"vanilla_phi_ty" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
vanilla_phi_ty
              , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"dm_phi_ty"      SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
dm_phi_ty ]

          -- Actually checking that the types align is done with a call to
          -- tcMatchTys. We need to get a match in both directions to rule
          -- out degenerate cases like these:
          --
          --  class Foo a where
          --    foo1         :: a -> b
          --    default foo1 :: a -> Int
          --
          --    foo2         :: a -> Int
          --    default foo2 :: a -> b
          Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Maybe Subst -> Bool
forall a. Maybe a -> Bool
isJust (Maybe Subst -> Bool) -> Maybe Subst -> Bool
forall a b. (a -> b) -> a -> b
$ ThetaType -> ThetaType -> Maybe Subst
tcMatchTys [Type
dm_phi_ty, Type
vanilla_phi_ty]
                                      [Type
vanilla_phi_ty, Type
dm_phi_ty]) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ TcRnMessage -> TcRn ()
addErrTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
               Var -> Type -> TcRnMessage
TcRnDefaultSigMismatch Var
sel_id Type
dm_ty

          -- Now do an ambiguity check on the default type signature.
          UserTypeCtxt -> Type -> TcRn ()
checkValidType UserTypeCtxt
ctxt (Class -> Var -> DefMethSpec Type -> Type
mkDefaultMethodType Class
cls Var
sel_id DefMethSpec Type
dm_spec)
    check_dm UserTypeCtxt
_ Var
_ Type
_ Type
_ DefMethInfo
_ = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

checkFamFlag :: Name -> TcM ()
-- Check that we don't use families without -XTypeFamilies
-- The parser won't even parse them, but I suppose a GHC API
-- client might have a go!
checkFamFlag :: Name -> TcRn ()
checkFamFlag Name
tc_name
  = do { idx_tys <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.TypeFamilies
       ; unless idx_tys $ addErrTc (TcRnTyFamsDisabled (TyFamsDisabledFamily tc_name)) }

checkResultSigFlag :: Name -> FamilyResultSig GhcRn -> TcM ()
checkResultSigFlag :: Name -> FamilyResultSig GhcRn -> TcRn ()
checkResultSigFlag Name
tc_name (TyVarSig XTyVarSig GhcRn
_ LHsTyVarBndr () GhcRn
tvb)
  = do { ty_fam_deps <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.TypeFamilyDependencies
       ; unless ty_fam_deps $ addErrTc (TcRnTyFamResultDisabled tc_name tvb) }
checkResultSigFlag Name
_ FamilyResultSig GhcRn
_ = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()  -- other cases OK

{- Note [Class method constraints]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Haskell 2010 is supposed to reject
  class C a where
    op :: Eq a => a -> a
where the method type constrains only the class variable(s).  (The extension
-XConstrainedClassMethods switches off this check.)  But regardless
we should not reject
  class C a where
    op :: (?x::Int) => a -> a
as pointed out in #11793. So the test here rejects the program if
  * -XConstrainedClassMethods is off
  * the tyvars of the constraint are non-empty
  * all the tyvars are class tyvars, none are locally quantified

Note [Abort when superclass cycle is detected]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We must avoid doing the ambiguity check for the methods (in
checkValidClass.check_op) when there are already errors accumulated.
This is because one of the errors may be a superclass cycle, and
superclass cycles cause canonicalization to loop. Here is a
representative example:

  class D a => C a where
    meth :: D a => ()
  class C a => D a

This fixes #9415, #9739

Note [Default method type signatures must align]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GHC enforces the invariant that a class method's default type signature
must "align" with that of the method's non-default type signature, as per
GHC #12918. For instance, if you have:

  class Foo a where
    bar :: forall b. Context => a -> b

Then a default type signature for bar must be alpha equivalent to
(forall b. a -> b). That is, the types must be the same modulo differences in
contexts. So the following would be acceptable default type signatures:

    default bar :: forall b. Context1 => a -> b
    default bar :: forall x. Context2 => a -> x

But the following are NOT acceptable default type signatures:

    default bar :: forall b. b -> a
    default bar :: forall x. x
    default bar :: a -> Int

Note that a is bound by the class declaration for Foo itself, so it is
not allowed to differ in the default type signature.

The default type signature (default bar :: a -> Int) deserves special mention,
since (a -> Int) is a straightforward instantiation of (forall b. a -> b). To
write this, you need to declare the default type signature like so:

    default bar :: forall b. (b ~ Int). a -> b

As noted in #12918, there are several reasons to do this:

1. It would make no sense to have a type that was flat-out incompatible with
   the non-default type signature. For instance, if you had:

     class Foo a where
       bar :: a -> Int
       default bar :: a -> Bool

   Then that would always fail in an instance declaration. So this check
   nips such cases in the bud before they have the chance to produce
   confusing error messages.

2. Internally, GHC uses TypeApplications to instantiate the default method in
   an instance. See Note [Default methods in instances] in GHC.Tc.TyCl.Instance.
   Thus, GHC needs to know exactly what the universally quantified type
   variables are, and when instantiated that way, the default method's type
   must match the expected type.

3. Aesthetically, by only allowing the default type signature to differ in its
   context, we are making it more explicit the ways in which the default type
   signature is less polymorphic than the non-default type signature.

You might be wondering: why are the contexts allowed to be different, but not
the rest of the type signature? That's because default implementations often
rely on assumptions that the more general, non-default type signatures do not.
For instance, in the Enum class declaration:

    class Enum a where
      enum :: [a]
      default enum :: (Generic a, GEnum (Rep a)) => [a]
      enum = map to genum

    class GEnum f where
      genum :: [f a]

The default implementation for enum only works for types that are instances of
Generic, and for which their generic Rep type is an instance of GEnum. But
clearly enum doesn't _have_ to use this implementation, so naturally, the
context for enum is allowed to be different to accommodate this. As a result,
when we validity-check default type signatures, we ignore contexts completely.

Note that when checking whether two type signatures match, we must take care to
split as many foralls as it takes to retrieve the tau types we which to check.
See Note [Splitting nested sigma types in class type signatures].

Extra note: July 22.  If we have
   class C a b where
      op :: op_ty
      default op :: def_ty
      op = blah

then we'll generate something like
   $gdm_op :: C a b => def_ty
   $gdm_op = blah

We expect to write an instance that looks (in effect) like this:
   instance G => C t1 t2 where
      op = $gdm_op  -- Added when you leave out binding for 'op'

So we need that
  assuming constraints G, and C t1 t2,
  we have (def_ty[t1/a,t2/b] <= op_ty[t1/a,t2/b]

In the validity check, we want to check that there is such a G.
E.g. if we check  def_ty <= op_ty, and get an insoluble constraint
(Int~Bool), we know there will never be such a G, and can complain.

This seems to be a more general way of thinking about the problem.
But no one is complaining, so it'll have to wait for another day

Note [Splitting nested sigma types in class type signatures]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider this type synonym and class definition:

  type Traversal s t a b = forall f. Applicative f => (a -> f b) -> s -> f t

  class Each s t a b where
    each         ::                                      Traversal s t a b
    default each :: (Traversable g, s ~ g a, t ~ g b) => Traversal s t a b

It might seem obvious that the tau types in both type signatures for `each`
are the same, but actually getting GHC to conclude this is surprisingly tricky.
That is because in general, the form of a class method's non-default type
signature is:

  forall a. C a => forall d. D d => E a b

And the general form of a default type signature is:

  forall f. F f => E a f -- The variable `a` comes from the class

So it you want to get the tau types in each type signature, you might find it
reasonable to call tcSplitSigmaTy twice on the non-default type signature, and
call it once on the default type signature. For most classes and methods, this
will work, but Each is a bit of an exceptional case. The way `each` is written,
it doesn't quantify any additional type variables besides those of the Each
class itself, so the non-default type signature for `each` is actually this:

  forall s t a b. Each s t a b => Traversal s t a b

Notice that there _appears_ to only be one forall. But there's actually another
forall lurking in the Traversal type synonym, so if you call tcSplitSigmaTy
twice, you'll also go under the forall in Traversal! That is, you'll end up
with:

  (a -> f b) -> s -> f t

A problem arises because you only call tcSplitSigmaTy once on the default type
signature for `each`, which gives you

  Traversal s t a b

Or, equivalently:

  forall f. Applicative f => (a -> f b) -> s -> f t

This is _not_ the same thing as (a -> f b) -> s -> f t! So now tcMatchTy will
say that the tau types for `each` are not equal.

A solution to this problem is to use tcSplitNestedSigmaTys instead of
tcSplitSigmaTy. tcSplitNestedSigmaTys will always split any foralls that it
sees until it can't go any further, so if you called it on the default type
signature for `each`, it would return (a -> f b) -> s -> f t like we desired.

Note [Checking partial record field]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This check checks the partial record field selector, and warns (#7169).

For example:

  data T a = A { m1 :: a, m2 :: a } | B { m1 :: a }

The function 'm2' is partial record field, and will fail when it is applied to
'B'. The warning identifies such partial fields. The check is performed at the
declaration of T, not at the call-sites of m2.

The warning can be suppressed by prefixing the field-name with an underscore.
For example:

  data T a = A { m1 :: a, _m2 :: a } | B { m1 :: a }

************************************************************************
*                                                                      *
                Checking role validity
*                                                                      *
************************************************************************
-}

checkValidRoleAnnots :: RoleAnnotEnv -> TyCon -> TcM ()
checkValidRoleAnnots :: RoleAnnotEnv -> TyCon -> TcRn ()
checkValidRoleAnnots RoleAnnotEnv
role_annots TyCon
tc
  | TyCon -> Bool
isTypeSynonymTyCon TyCon
tc = TcRn ()
check_no_roles
  | TyCon -> Bool
isFamilyTyCon TyCon
tc      = TcRn ()
check_no_roles
  | TyCon -> Bool
isAlgTyCon TyCon
tc         = TcRn ()
check_roles
  | Bool
otherwise             = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  where
    -- Role annotations are given only on *explicit* variables,
    -- but a tycon stores roles for all variables.
    -- So, we drop the implicit roles (which are all Nominal, anyway).
    name :: Name
name                   = TyCon -> Name
tyConName TyCon
tc
    roles :: [Role]
roles                  = TyCon -> [Role]
tyConRoles TyCon
tc
    ([Role]
vis_roles, [Var]
vis_vars)  = [(Role, Var)] -> ([Role], [Var])
forall a b. [(a, b)] -> ([a], [b])
unzip ([(Role, Var)] -> ([Role], [Var]))
-> [(Role, Var)] -> ([Role], [Var])
forall a b. (a -> b) -> a -> b
$ ((Role, TyConBinder) -> Maybe (Role, Var))
-> [(Role, TyConBinder)] -> [(Role, Var)]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe (Role, TyConBinder) -> Maybe (Role, Var)
pick_vis ([(Role, TyConBinder)] -> [(Role, Var)])
-> [(Role, TyConBinder)] -> [(Role, Var)]
forall a b. (a -> b) -> a -> b
$
                             [Role] -> [TyConBinder] -> [(Role, TyConBinder)]
forall a b. [a] -> [b] -> [(a, b)]
zip [Role]
roles (TyCon -> [TyConBinder]
tyConBinders TyCon
tc)
    role_annot_decl_maybe :: Maybe (LRoleAnnotDecl GhcRn)
role_annot_decl_maybe  = RoleAnnotEnv -> Name -> Maybe (LRoleAnnotDecl GhcRn)
lookupRoleAnnot RoleAnnotEnv
role_annots Name
name

    pick_vis :: (Role, TyConBinder) -> Maybe (Role, TyVar)
    pick_vis :: (Role, TyConBinder) -> Maybe (Role, Var)
pick_vis (Role
role, TyConBinder
tvb)
      | TyConBinder -> Bool
forall tv. VarBndr tv TyConBndrVis -> Bool
isVisibleTyConBinder TyConBinder
tvb = (Role, Var) -> Maybe (Role, Var)
forall a. a -> Maybe a
Just (Role
role, TyConBinder -> Var
forall tv argf. VarBndr tv argf -> tv
binderVar TyConBinder
tvb)
      | Bool
otherwise                = Maybe (Role, Var)
forall a. Maybe a
Nothing

    check_roles :: TcRn ()
check_roles = case Maybe (LRoleAnnotDecl GhcRn)
role_annot_decl_maybe of
      Maybe (LRoleAnnotDecl GhcRn)
Nothing ->
          SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Name -> SrcSpan
forall a. NamedThing a => a -> SrcSpan
getSrcSpan Name
name) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          -- See Note [Missing role annotations warning]
          Bool -> TcRnMessage -> TcRn ()
warnIf (Bool -> Bool
not (TyCon -> Bool
isClassTyCon TyCon
tc) Bool -> Bool -> Bool
&& Bool -> Bool
not ([Role] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Role]
vis_roles)) (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          Name -> [Role] -> TcRnMessage
TcRnMissingRoleAnnotation Name
name [Role]
vis_roles
      Just (decl :: LRoleAnnotDecl GhcRn
decl@(L SrcSpanAnnA
loc (RoleAnnotDecl XCRoleAnnotDecl GhcRn
_ LIdP GhcRn
_ [XRec GhcRn (Maybe Role)]
the_role_annots))) ->
          Name -> TcRn () -> TcRn ()
forall a. Name -> TcM a -> TcM a
addRoleAnnotCtxt Name
name (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
          SrcSpanAnnA -> TcRn () -> TcRn ()
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$ do
          { role_annots_ok <- Extension -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.RoleAnnotations
          ; unless role_annots_ok $ addErrTc $ TcRnRoleAnnotationsDisabled tc
          ; checkTc (vis_vars `equalLength` the_role_annots)
                    (TcRnRoleCountMismatch (length vis_vars) decl)
          ; _ <- zipWith3M checkRoleAnnot vis_vars the_role_annots vis_roles
          -- Representational or phantom roles for class parameters
          -- quickly lead to incoherence. So, we require
          -- IncoherentInstances to have them. See #8773, #14292
          ; incoherent_roles_ok <- xoptM LangExt.IncoherentInstances
          ; checkTc (  incoherent_roles_ok
                    || (not $ isClassTyCon tc)
                    || (all (== Nominal) vis_roles))
                    (TcRnIncoherentRoles tc)

          ; lint <- goptM Opt_DoCoreLinting
          ; when lint $ checkValidRoles tc }

    check_no_roles :: TcRn ()
check_no_roles
      = Maybe (GenLocated SrcSpanAnnA (RoleAnnotDecl GhcRn))
-> (GenLocated SrcSpanAnnA (RoleAnnotDecl GhcRn) -> TcRn ())
-> TcRn ()
forall (m :: * -> *) a. Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust Maybe (LRoleAnnotDecl GhcRn)
Maybe (GenLocated SrcSpanAnnA (RoleAnnotDecl GhcRn))
role_annot_decl_maybe LRoleAnnotDecl GhcRn -> TcRn ()
GenLocated SrcSpanAnnA (RoleAnnotDecl GhcRn) -> TcRn ()
illegalRoleAnnotDecl

-- Note [Missing role annotations warning]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- We warn about missing role annotations for tycons
-- 1. not type-classes:
--    type classes are nominal by default, which is most conservative
--    choice. E.g. we cannot have a type-class with an (accidentally)
--    phantom or representational type variable, as we can with
--    data types.
-- 2. with visible roles
--
-- We don't make any exceptions for other data types.
-- In particular we explicitly warn about omitted (default and common)
-- representational roles. That is the point of the warning.
-- For example the default representational role for `Map`s key type parameter
-- would be wrong, and this warning is there to warn about it,
-- asking users to be explicit.
--
-- If the default roles have been nominal, i.e. as conservative as possible,
-- the warning would still be valuable, as most types can be `representational`
-- (c.f. type-classes, which usually cannot).
--
-- We don't warn about types with invisible roles only, because users cannot
-- specify them:
--
--    type Foo :: forall {k}. Type
--    data Foo = Foo Int
--    type role Foo phantom
--
-- is incorrect, GHC complains:
-- Wrong number of roles listed in role annotation;
-- Expected 0, got 1:
--

checkRoleAnnot :: TyVar -> LocatedAn NoEpAnns (Maybe Role) -> Role -> TcM ()
checkRoleAnnot :: Var -> GenLocated EpAnnCO (Maybe Role) -> Role -> TcRn ()
checkRoleAnnot Var
_  (L EpAnnCO
_ Maybe Role
Nothing)   Role
_  = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
checkRoleAnnot Var
tv (L EpAnnCO
_ (Just Role
r1)) Role
r2
  = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Role
r1 Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
/= Role
r2) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    TcRnMessage -> TcRn ()
addErrTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Name -> Role -> Role -> TcRnMessage
TcRnRoleMismatch (Var -> Name
tyVarName Var
tv) Role
r1 Role
r2

-- This is a double-check on the role inference algorithm. It is only run when
-- -dcore-lint is enabled. See Note [Role inference] in GHC.Tc.TyCl.Utils
checkValidRoles :: TyCon -> TcM ()
-- If you edit this function, you may need to update the GHC formalism
-- See Note [GHC Formalism] in GHC.Core.Lint
checkValidRoles :: TyCon -> TcRn ()
checkValidRoles TyCon
tc
  | TyCon -> Bool
isAlgTyCon TyCon
tc
    -- tyConDataCons returns an empty list for data families
  = (DataCon -> TcRn ()) -> [DataCon] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ DataCon -> TcRn ()
check_dc_roles (TyCon -> [DataCon]
tyConDataCons TyCon
tc)
  | Just Type
rhs <- TyCon -> Maybe Type
synTyConRhs_maybe TyCon
tc
  = VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles ([Var] -> [Role] -> VarEnv Role
forall a. [Var] -> [a] -> VarEnv a
zipVarEnv (TyCon -> [Var]
tyConTyVars TyCon
tc) (TyCon -> [Role]
tyConRoles TyCon
tc)) Role
Representational Type
rhs
  | Bool
otherwise
  = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  where
    check_dc_roles :: DataCon -> TcRn ()
check_dc_roles DataCon
datacon
      = do { String -> SDoc -> TcRn ()
traceTc String
"check_dc_roles" (DataCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr DataCon
datacon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [Role] -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyCon -> [Role]
tyConRoles TyCon
tc))
           ; (Type -> TcRn ()) -> ThetaType -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
role_env Role
Representational) (ThetaType -> TcRn ()) -> ThetaType -> TcRn ()
forall a b. (a -> b) -> a -> b
$
             [EqSpec] -> ThetaType
eqSpecPreds [EqSpec]
eq_spec ThetaType -> ThetaType -> ThetaType
forall a. [a] -> [a] -> [a]
++ ThetaType
theta ThetaType -> ThetaType -> ThetaType
forall a. [a] -> [a] -> [a]
++ (Scaled Type -> Type) -> [Scaled Type] -> ThetaType
forall a b. (a -> b) -> [a] -> [b]
map Scaled Type -> Type
forall a. Scaled a -> a
scaledThing [Scaled Type]
arg_tys }
                    -- See Note [Role-checking data constructor arguments] in GHC.Tc.TyCl.Utils
      where
        ([Var]
univ_tvs, [Var]
ex_tvs, [EqSpec]
eq_spec, ThetaType
theta, [Scaled Type]
arg_tys, Type
_res_ty)
          = DataCon -> ([Var], [Var], [EqSpec], ThetaType, [Scaled Type], Type)
dataConFullSig DataCon
datacon
        univ_roles :: VarEnv Role
univ_roles = [Var] -> [Role] -> VarEnv Role
forall a. [Var] -> [a] -> VarEnv a
zipVarEnv [Var]
univ_tvs (TyCon -> [Role]
tyConRoles TyCon
tc)
              -- zipVarEnv uses zipEqual, but we don't want that for ex_tvs
        ex_roles :: VarEnv Role
ex_roles   = [(Var, Role)] -> VarEnv Role
forall a. [(Var, a)] -> VarEnv a
mkVarEnv ((Var -> (Var, Role)) -> [Var] -> [(Var, Role)]
forall a b. (a -> b) -> [a] -> [b]
map (, Role
Nominal) [Var]
ex_tvs)
        role_env :: VarEnv Role
role_env   = VarEnv Role
univ_roles VarEnv Role -> VarEnv Role -> VarEnv Role
forall a. VarEnv a -> VarEnv a -> VarEnv a
`plusVarEnv` VarEnv Role
ex_roles

    check_ty_roles :: VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
role Type
ty
      | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty -- #14101
      = VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
role Type
ty'

    check_ty_roles VarEnv Role
env Role
role (TyVarTy Var
tv)
      = case VarEnv Role -> Var -> Maybe Role
forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv VarEnv Role
env Var
tv of
          Just Role
role' -> Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Role
role' Role -> Role -> Bool
`ltRole` Role
role Bool -> Bool -> Bool
|| Role
role' Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
role) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                        Role -> RoleValidationFailedReason -> TcRn ()
report_error Role
role (RoleValidationFailedReason -> TcRn ())
-> RoleValidationFailedReason -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Var -> Role -> RoleValidationFailedReason
TyVarRoleMismatch Var
tv Role
role'
          Maybe Role
Nothing    -> Role -> RoleValidationFailedReason -> TcRn ()
report_error Role
role (RoleValidationFailedReason -> TcRn ())
-> RoleValidationFailedReason -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Var -> RoleValidationFailedReason
TyVarMissingInEnv Var
tv

    check_ty_roles VarEnv Role
env Role
Representational (TyConApp TyCon
tc ThetaType
tys)
      = let roles' :: [Role]
roles' = TyCon -> [Role]
tyConRoles TyCon
tc in
        (Role -> Type -> TcRn ()) -> [Role] -> ThetaType -> TcRn ()
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m ()
zipWithM_ (VarEnv Role -> Role -> Type -> TcRn ()
maybe_check_ty_roles VarEnv Role
env) [Role]
roles' ThetaType
tys

    check_ty_roles VarEnv Role
env Role
Nominal (TyConApp TyCon
_ ThetaType
tys)
      = (Type -> TcRn ()) -> ThetaType -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
Nominal) ThetaType
tys

    check_ty_roles VarEnv Role
_   Role
Phantom ty :: Type
ty@(TyConApp {})
      = String -> SDoc -> TcRn ()
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"check_ty_roles" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

    check_ty_roles VarEnv Role
env Role
role (AppTy Type
ty1 Type
ty2)
      =  VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
role    Type
ty1
      TcRn () -> TcRn () -> TcRn ()
forall a b.
IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
Nominal Type
ty2

    check_ty_roles VarEnv Role
env Role
role (FunTy FunTyFlag
_ Type
w Type
ty1 Type
ty2)
      =  VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
Nominal Type
w
      TcRn () -> TcRn () -> TcRn ()
forall a b.
IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
role Type
ty1
      TcRn () -> TcRn () -> TcRn ()
forall a b.
IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
role Type
ty2

    check_ty_roles VarEnv Role
env Role
role (ForAllTy (Bndr Var
tv ForAllTyFlag
_) Type
ty)
      =  VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
Nominal (Var -> Type
tyVarKind Var
tv)
      TcRn () -> TcRn () -> TcRn ()
forall a b.
IOEnv (Env TcGblEnv TcLclEnv) a
-> IOEnv (Env TcGblEnv TcLclEnv) b
-> IOEnv (Env TcGblEnv TcLclEnv) b
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles (VarEnv Role -> Var -> Role -> VarEnv Role
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv VarEnv Role
env Var
tv Role
Nominal) Role
role Type
ty

    check_ty_roles VarEnv Role
_   Role
_    (LitTy {}) = () -> TcRn ()
forall a. a -> IOEnv (Env TcGblEnv TcLclEnv) a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    check_ty_roles VarEnv Role
env Role
role (CastTy Type
t Coercion
_)
      = VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
role Type
t

    check_ty_roles VarEnv Role
_   Role
role (CoercionTy Coercion
co)
      = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Role
role Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
Phantom) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        Role -> RoleValidationFailedReason -> TcRn ()
report_error Role
role (RoleValidationFailedReason -> TcRn ())
-> RoleValidationFailedReason -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Coercion -> RoleValidationFailedReason
BadCoercionRole Coercion
co

    maybe_check_ty_roles :: VarEnv Role -> Role -> Type -> TcRn ()
maybe_check_ty_roles VarEnv Role
env Role
role Type
ty
      = Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Role
role Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
Nominal Bool -> Bool -> Bool
|| Role
role Role -> Role -> Bool
forall a. Eq a => a -> a -> Bool
== Role
Representational) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
        VarEnv Role -> Role -> Type -> TcRn ()
check_ty_roles VarEnv Role
env Role
role Type
ty

    report_error :: Role -> RoleValidationFailedReason -> TcRn ()
report_error Role
role RoleValidationFailedReason
reason
      = TcRnMessage -> TcRn ()
addErrTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Role -> RoleValidationFailedReason -> TcRnMessage
TcRnRoleValidationFailed Role
role RoleValidationFailedReason
reason

{-
************************************************************************
*                                                                      *
                Error messages
*                                                                      *
************************************************************************
-}

tcMkDeclCtxt :: TyClDecl GhcRn -> SDoc
tcMkDeclCtxt :: TyClDecl GhcRn -> SDoc
tcMkDeclCtxt TyClDecl GhcRn
decl = [SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
hsep [String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the", TyClDecl GhcRn -> SDoc
forall (p :: Pass). TyClDecl (GhcPass p) -> SDoc
pprTyClDeclFlavour TyClDecl GhcRn
decl,
                      String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"declaration for", SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr (TyClDecl GhcRn -> IdP GhcRn
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyClDecl (GhcPass p) -> IdP (GhcPass p)
tcdName TyClDecl GhcRn
decl))]

addVDQNote :: TcTyCon -> TcM a -> TcM a
-- See Note [Inferring visible dependent quantification]
-- Only types without a signature (CUSK or SAKS) here
addVDQNote :: forall a. TyCon -> TcM a -> TcM a
addVDQNote TyCon
tycon TcM a
thing_inside
  | Bool -> SDoc -> Bool -> Bool
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr (TyCon -> Bool
isMonoTcTyCon TyCon
tycon) (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tycon SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
tc_kind)
    Bool
has_vdq
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addLandmarkErrCtxt SDoc
vdq_warning TcM a
thing_inside
  | Bool
otherwise
  = TcM a
thing_inside
  where
      -- Check whether a tycon has visible dependent quantification.
      -- This will *always* be a TcTyCon. Furthermore, it will *always*
      -- be an ungeneralised TcTyCon, straight out of kcInferDeclHeader.
      -- Thus, all the TyConBinders will be anonymous. Thus, the
      -- free variables of the tycon's kind will be the same as the free
      -- variables from all the binders.
    has_vdq :: Bool
has_vdq  = (TyConBinder -> Bool) -> [TyConBinder] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any TyConBinder -> Bool
is_vdq_tcb (TyCon -> [TyConBinder]
tyConBinders TyCon
tycon)
    tc_kind :: Type
tc_kind  = TyCon -> Type
tyConKind TyCon
tycon
    kind_fvs :: VarSet
kind_fvs = Type -> VarSet
tyCoVarsOfType Type
tc_kind

    is_vdq_tcb :: TyConBinder -> Bool
is_vdq_tcb TyConBinder
tcb = (TyConBinder -> Var
forall tv argf. VarBndr tv argf -> tv
binderVar TyConBinder
tcb Var -> VarSet -> Bool
`elemVarSet` VarSet
kind_fvs) Bool -> Bool -> Bool
&&
                     TyConBinder -> Bool
forall tv. VarBndr tv TyConBndrVis -> Bool
isVisibleTyConBinder TyConBinder
tcb

    vdq_warning :: SDoc
vdq_warning = [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
      [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"NB: Type" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> SDoc
quotes (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tycon) SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+>
        String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"was inferred to use visible dependent quantification."
      , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Most types with visible dependent quantification are"
      , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"polymorphically recursive and need a standalone kind"
      , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"signature. Perhaps supply one, with StandaloneKindSignatures."
      ]

tcAddDeclCtxt :: TyClDecl GhcRn -> TcM a -> TcM a
tcAddDeclCtxt :: forall a. TyClDecl GhcRn -> TcM a -> TcM a
tcAddDeclCtxt TyClDecl GhcRn
decl TcM a
thing_inside
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (TyClDecl GhcRn -> SDoc
tcMkDeclCtxt TyClDecl GhcRn
decl) TcM a
thing_inside

tcAddTyFamInstCtxt :: TyFamInstDecl GhcRn -> TcM a -> TcM a
tcAddTyFamInstCtxt :: forall a. TyFamInstDecl GhcRn -> TcM a -> TcM a
tcAddTyFamInstCtxt TyFamInstDecl GhcRn
decl
  = SDoc -> Name -> TcM a -> TcM a
forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt (String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"type instance") (TyFamInstDecl GhcRn -> IdP GhcRn
forall (p :: Pass).
(Anno (IdGhcP p) ~ SrcSpanAnnN) =>
TyFamInstDecl (GhcPass p) -> IdP (GhcPass p)
tyFamInstDeclName TyFamInstDecl GhcRn
decl)

tcMkDataFamInstCtxt :: DataFamInstDecl GhcRn -> SDoc
tcMkDataFamInstCtxt :: DataFamInstDecl GhcRn -> SDoc
tcMkDataFamInstCtxt decl :: DataFamInstDecl GhcRn
decl@(DataFamInstDecl { dfid_eqn :: forall pass. DataFamInstDecl pass -> FamEqn pass (HsDataDefn pass)
dfid_eqn = FamEqn GhcRn (HsDataDefn GhcRn)
eqn })
  = SDoc -> Name -> SDoc
tcMkFamInstCtxt (DataFamInstDecl GhcRn -> SDoc
forall (p :: Pass). DataFamInstDecl (GhcPass p) -> SDoc
pprDataFamInstFlavour DataFamInstDecl GhcRn
decl SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"instance")
                    (LocatedN Name -> Name
forall l e. GenLocated l e -> e
unLoc (FamEqn GhcRn (HsDataDefn GhcRn) -> LIdP GhcRn
forall pass rhs. FamEqn pass rhs -> LIdP pass
feqn_tycon FamEqn GhcRn (HsDataDefn GhcRn)
eqn))

tcAddDataFamInstCtxt :: DataFamInstDecl GhcRn -> TcM a -> TcM a
tcAddDataFamInstCtxt :: forall a. DataFamInstDecl GhcRn -> TcM a -> TcM a
tcAddDataFamInstCtxt DataFamInstDecl GhcRn
decl
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (DataFamInstDecl GhcRn -> SDoc
tcMkDataFamInstCtxt DataFamInstDecl GhcRn
decl)

tcMkFamInstCtxt :: SDoc -> Name -> SDoc
tcMkFamInstCtxt :: SDoc -> Name -> SDoc
tcMkFamInstCtxt SDoc
flavour Name
tycon
  = [SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
hsep [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
flavour SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"declaration for"
         , SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
tycon) ]

tcAddFamInstCtxt :: SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt :: forall a. SDoc -> Name -> TcM a -> TcM a
tcAddFamInstCtxt SDoc
flavour Name
tycon TcM a
thing_inside
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (SDoc -> Name -> SDoc
tcMkFamInstCtxt SDoc
flavour Name
tycon) TcM a
thing_inside

tcAddClosedTypeFamilyDeclCtxt :: TyCon -> TcM a -> TcM a
tcAddClosedTypeFamilyDeclCtxt :: forall a. TyCon -> TcM a -> TcM a
tcAddClosedTypeFamilyDeclCtxt TyCon
tc
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt SDoc
ctxt
  where
    ctxt :: SDoc
ctxt = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the equations for closed type family" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+>
           SDoc -> SDoc
quotes (TyCon -> SDoc
forall a. Outputable a => a -> SDoc
ppr TyCon
tc)

dataConCtxt :: NonEmpty (LocatedN Name) -> SDoc
dataConCtxt :: NonEmpty (LocatedN Name) -> SDoc
dataConCtxt NonEmpty (LocatedN Name)
cons = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the definition of data constructor" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> [LocatedN Name] -> SDoc
forall a. [a] -> SDoc
plural (NonEmpty (LocatedN Name) -> [LocatedN Name]
forall a. NonEmpty a -> [a]
forall (t :: * -> *) a. Foldable t => t a -> [a]
toList NonEmpty (LocatedN Name)
cons)
                   SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [LocatedN Name] -> SDoc
ppr_cons (NonEmpty (LocatedN Name) -> [LocatedN Name]
forall a. NonEmpty a -> [a]
forall (t :: * -> *) a. Foldable t => t a -> [a]
toList NonEmpty (LocatedN Name)
cons)

dataConResCtxt :: NonEmpty (LocatedN Name) -> SDoc
dataConResCtxt :: NonEmpty (LocatedN Name) -> SDoc
dataConResCtxt NonEmpty (LocatedN Name)
cons = String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"In the result type of data constructor" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> [LocatedN Name] -> SDoc
forall a. [a] -> SDoc
plural (NonEmpty (LocatedN Name) -> [LocatedN Name]
forall a. NonEmpty a -> [a]
forall (t :: * -> *) a. Foldable t => t a -> [a]
toList NonEmpty (LocatedN Name)
cons)
                      SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> [LocatedN Name] -> SDoc
ppr_cons (NonEmpty (LocatedN Name) -> [LocatedN Name]
forall a. NonEmpty a -> [a]
forall (t :: * -> *) a. Foldable t => t a -> [a]
toList NonEmpty (LocatedN Name)
cons)

ppr_cons :: [LocatedN Name] -> SDoc
ppr_cons :: [LocatedN Name] -> SDoc
ppr_cons [LocatedN Name
con] = SDoc -> SDoc
quotes (LocatedN Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr LocatedN Name
con)
ppr_cons [LocatedN Name]
cons  = [LocatedN Name] -> SDoc
forall a. Outputable a => [a] -> SDoc
interpp'SP [LocatedN Name]
cons

classOpCtxt :: Var -> Type -> SDoc
classOpCtxt :: Var -> Type -> SDoc
classOpCtxt Var
sel_id Type
tau = [SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep [String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"When checking the class method:",
                              Int -> SDoc -> SDoc
nest Int
2 (Var -> SDoc
forall a. OutputableBndr a => a -> SDoc
pprPrefixOcc Var
sel_id SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
tau)]

illegalRoleAnnotDecl :: LRoleAnnotDecl GhcRn -> TcM ()
illegalRoleAnnotDecl :: LRoleAnnotDecl GhcRn -> TcRn ()
illegalRoleAnnotDecl (L SrcSpanAnnA
loc RoleAnnotDecl GhcRn
role)
  = [ErrCtxt] -> TcRn () -> TcRn ()
forall a. [ErrCtxt] -> TcM a -> TcM a
setErrCtxt [] (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SrcSpanAnnA -> TcRn () -> TcRn ()
forall ann a. EpAnn ann -> TcRn a -> TcRn a
setSrcSpanA SrcSpanAnnA
loc (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    TcRnMessage -> TcRn ()
addErrTc (TcRnMessage -> TcRn ()) -> TcRnMessage -> TcRn ()
forall a b. (a -> b) -> a -> b
$ RoleAnnotDecl GhcRn -> TcRnMessage
TcRnIllegalRoleAnnotation RoleAnnotDecl GhcRn
role

addTyConCtxt :: TyCon -> TcM a -> TcM a
addTyConCtxt :: forall a. TyCon -> TcM a -> TcM a
addTyConCtxt TyCon
tc = Name -> TyConFlavour TyCon -> TcM a -> TcM a
forall tc a. Name -> TyConFlavour tc -> TcM a -> TcM a
addTyConFlavCtxt Name
name TyConFlavour TyCon
flav
  where
    name :: Name
name = TyCon -> Name
forall a. NamedThing a => a -> Name
getName TyCon
tc
    flav :: TyConFlavour TyCon
flav = TyCon -> TyConFlavour TyCon
tyConFlavour TyCon
tc

addRoleAnnotCtxt :: Name -> TcM a -> TcM a
addRoleAnnotCtxt :: forall a. Name -> TcM a -> TcM a
addRoleAnnotCtxt Name
name
  = SDoc -> TcM a -> TcM a
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (SDoc -> TcM a -> TcM a) -> SDoc -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"while checking a role annotation for" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name)