{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998

-}

{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ViewPatterns #-}

{-# OPTIONS_GHC -Wno-incomplete-record-updates #-}

-- | Typechecking pattern synonym declarations
module GHC.Tc.TyCl.PatSyn
   ( tcPatSynDecl
   , tcPatSynBuilderBind
   , tcPatSynBuilderOcc
   , nonBidirectionalErr
   )
where

import GHC.Prelude

import GHC.Hs
import GHC.Tc.Gen.Pat
import GHC.Core.Multiplicity
import GHC.Core.Type ( tidyTyCoVarBinders, tidyTypes, tidyType )
import GHC.Tc.Utils.Monad
import GHC.Tc.Gen.Sig( emptyPragEnv, completeSigFromId )
import GHC.Tc.Utils.Env
import GHC.Tc.Utils.TcMType
import GHC.Tc.Utils.Zonk
import GHC.Builtin.Types.Prim
import GHC.Types.Name
import GHC.Types.SrcLoc
import GHC.Core.PatSyn
import GHC.Types.Name.Set
import GHC.Utils.Panic
import GHC.Utils.Outputable
import GHC.Data.FastString
import GHC.Types.Var
import GHC.Types.Var.Env( emptyTidyEnv, mkInScopeSet )
import GHC.Types.Id
import GHC.Types.Id.Info( RecSelParent(..), setLevityInfoWithType )
import GHC.Tc.Gen.Bind
import GHC.Types.Basic
import GHC.Tc.Solver
import GHC.Tc.Utils.Unify
import GHC.Core.Predicate
import GHC.Builtin.Types
import GHC.Tc.Utils.TcType
import GHC.Tc.Types.Evidence
import GHC.Tc.Types.Origin
import GHC.Tc.TyCl.Build
import GHC.Types.Var.Set
import GHC.Types.Id.Make
import GHC.Tc.TyCl.Utils
import GHC.Core.ConLike
import GHC.Types.FieldLabel
import GHC.Data.Bag
import GHC.Utils.Misc
import GHC.Utils.Error
import GHC.Driver.Session ( getDynFlags )
import Data.Maybe( mapMaybe )
import Control.Monad ( zipWithM )
import Data.List( partition )

#include "HsVersions.h"

{-
************************************************************************
*                                                                      *
                    Type checking a pattern synonym
*                                                                      *
************************************************************************
-}

tcPatSynDecl :: PatSynBind GhcRn GhcRn
             -> Maybe TcSigInfo
             -> TcM (LHsBinds GhcTc, TcGblEnv)
tcPatSynDecl :: PatSynBind GhcRn GhcRn
-> Maybe TcSigInfo -> TcM (LHsBinds GhcTc, TcGblEnv)
tcPatSynDecl PatSynBind GhcRn GhcRn
psb Maybe TcSigInfo
mb_sig
  = TcM (LHsBinds GhcTc, TcGblEnv)
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall r. TcRn r -> TcRn r -> TcRn r
recoverM (PatSynBind GhcRn GhcRn -> TcM (LHsBinds GhcTc, TcGblEnv)
recoverPSB PatSynBind GhcRn GhcRn
psb) (TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv))
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a b. (a -> b) -> a -> b
$
    case Maybe TcSigInfo
mb_sig of
      Maybe TcSigInfo
Nothing                 -> PatSynBind GhcRn GhcRn -> TcM (LHsBinds GhcTc, TcGblEnv)
tcInferPatSynDecl PatSynBind GhcRn GhcRn
psb
      Just (TcPatSynSig TcPatSynInfo
tpsi) -> PatSynBind GhcRn GhcRn
-> TcPatSynInfo -> TcM (LHsBinds GhcTc, TcGblEnv)
tcCheckPatSynDecl PatSynBind GhcRn GhcRn
psb TcPatSynInfo
tpsi
      Maybe TcSigInfo
_                       -> String -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a. String -> a
panic String
"tcPatSynDecl"

recoverPSB :: PatSynBind GhcRn GhcRn
           -> TcM (LHsBinds GhcTc, TcGblEnv)
-- See Note [Pattern synonym error recovery]
recoverPSB :: PatSynBind GhcRn GhcRn -> TcM (LHsBinds GhcTc, TcGblEnv)
recoverPSB (PSB { psb_id :: forall idL idR. PatSynBind idL idR -> Located (IdP idL)
psb_id = L SrcSpan
_ IdP GhcRn
name
                , psb_args :: forall idL idR.
PatSynBind idL idR -> HsPatSynDetails (Located (IdP idR))
psb_args = HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details })
 = do { Name
matcher_name <- Name -> (OccName -> OccName) -> TcRnIf TcGblEnv TcLclEnv Name
forall m n. Name -> (OccName -> OccName) -> TcRnIf m n Name
newImplicitBinder Name
IdP GhcRn
name OccName -> OccName
mkMatcherOcc
      ; let placeholder :: TyThing
placeholder = ConLike -> TyThing
AConLike (ConLike -> TyThing) -> ConLike -> TyThing
forall a b. (a -> b) -> a -> b
$ PatSyn -> ConLike
PatSynCon (PatSyn -> ConLike) -> PatSyn -> ConLike
forall a b. (a -> b) -> a -> b
$
                          Name -> PatSyn
mk_placeholder Name
matcher_name
      ; TcGblEnv
gbl_env <- [TyThing] -> TcM TcGblEnv -> TcM TcGblEnv
forall r. [TyThing] -> TcM r -> TcM r
tcExtendGlobalEnv [TyThing
placeholder] TcM TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
      ; (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall (m :: * -> *) a. Monad m => a -> m a
return (LHsBinds GhcTc
forall a. Bag a
emptyBag, TcGblEnv
gbl_env) }
  where
    ([Name]
_arg_names, [Name]
_rec_fields, Bool
is_infix) = HsPatSynDetails (Located Name) -> ([Name], [Name], Bool)
collectPatSynArgInfo HsPatSynDetails (Located Name)
HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details
    mk_placeholder :: Name -> PatSyn
mk_placeholder Name
matcher_name
      = Name
-> Bool
-> ([VarBndr Id Specificity], [Kind])
-> ([VarBndr Id Specificity], [Kind])
-> [Kind]
-> Kind
-> (Id, Bool)
-> Maybe (Id, Bool)
-> [FieldLabel]
-> PatSyn
mkPatSyn Name
IdP GhcRn
name Bool
is_infix
                        ([Specificity -> Id -> VarBndr Id Specificity
forall vis. vis -> Id -> VarBndr Id vis
mkTyVarBinder Specificity
SpecifiedSpec Id
alphaTyVar], []) ([], [])
                        [] -- Arg tys
                        Kind
alphaTy
                        (Id
matcher_id, Bool
True) Maybe (Id, Bool)
forall a. Maybe a
Nothing
                        []  -- Field labels
       where
         -- The matcher_id is used only by the desugarer, so actually
         -- and error-thunk would probably do just as well here.
         matcher_id :: Id
matcher_id = HasDebugCallStack => Name -> Kind -> Kind -> Id
Name -> Kind -> Kind -> Id
mkLocalId Name
matcher_name Kind
Many (Kind -> Id) -> Kind -> Id
forall a b. (a -> b) -> a -> b
$
                      [Id] -> Kind -> Kind
mkSpecForAllTys [Id
alphaTyVar] Kind
alphaTy

{- Note [Pattern synonym error recovery]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If type inference for a pattern synonym fails, we can't continue with
the rest of tc_patsyn_finish, because we may get knock-on errors, or
even a crash.  E.g. from
   pattern What = True :: Maybe
we get a kind error; and we must stop right away (#15289).

We stop if there are /any/ unsolved constraints, not just insoluble
ones; because pattern synonyms are top-level things, we will never
solve them later if we can't solve them now.  And if we were to carry
on, tc_patsyn_finish does zonkTcTypeToType, which defaults any
unsolved unificatdion variables to Any, which confuses the error
reporting no end (#15685).

So we use simplifyTop to completely solve the constraint, report
any errors, throw an exception.

Even in the event of such an error we can recover and carry on, just
as we do for value bindings, provided we plug in placeholder for the
pattern synonym: see recoverPSB.  The goal of the placeholder is not
to cause a raft of follow-on errors.  I've used the simplest thing for
now, but we might need to elaborate it a bit later.  (e.g.  I've given
it zero args, which may cause knock-on errors if it is used in a
pattern.) But it'll do for now.

-}

tcInferPatSynDecl :: PatSynBind GhcRn GhcRn
                  -> TcM (LHsBinds GhcTc, TcGblEnv)
tcInferPatSynDecl :: PatSynBind GhcRn GhcRn -> TcM (LHsBinds GhcTc, TcGblEnv)
tcInferPatSynDecl (PSB { psb_id :: forall idL idR. PatSynBind idL idR -> Located (IdP idL)
psb_id = lname :: GenLocated SrcSpan (IdP GhcRn)
lname@(L SrcSpan
_ IdP GhcRn
name), psb_args :: forall idL idR.
PatSynBind idL idR -> HsPatSynDetails (Located (IdP idR))
psb_args = HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details
                       , psb_def :: forall idL idR. PatSynBind idL idR -> LPat idR
psb_def = LPat GhcRn
lpat, psb_dir :: forall idL idR. PatSynBind idL idR -> HsPatSynDir idR
psb_dir = HsPatSynDir GhcRn
dir })
  = Located Name
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a. Located Name -> TcM a -> TcM a
addPatSynCtxt Located Name
GenLocated SrcSpan (IdP GhcRn)
lname (TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv))
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a b. (a -> b) -> a -> b
$
    do { String -> MsgDoc -> TcRn ()
traceTc String
"tcInferPatSynDecl {" (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
IdP GhcRn
name

       ; let ([Name]
arg_names, [Name]
rec_fields, Bool
is_infix) = HsPatSynDetails (Located Name) -> ([Name], [Name], Bool)
collectPatSynArgInfo HsPatSynDetails (Located Name)
HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details
       ; (TcLevel
tclvl, WantedConstraints
wanted, ((Located (Pat GhcTc)
lpat', [Id]
args), Kind
pat_ty))
            <- TcM ((Located (Pat GhcTc), [Id]), Kind)
-> TcM
     (TcLevel, WantedConstraints, ((Located (Pat GhcTc), [Id]), Kind))
forall a. TcM a -> TcM (TcLevel, WantedConstraints, a)
pushLevelAndCaptureConstraints  (TcM ((Located (Pat GhcTc), [Id]), Kind)
 -> TcM
      (TcLevel, WantedConstraints, ((Located (Pat GhcTc), [Id]), Kind)))
-> TcM ((Located (Pat GhcTc), [Id]), Kind)
-> TcM
     (TcLevel, WantedConstraints, ((Located (Pat GhcTc), [Id]), Kind))
forall a b. (a -> b) -> a -> b
$
               HsMatchContext GhcRn
-> LPat GhcRn -> TcM [Id] -> TcM ((LPat GhcTc, [Id]), Kind)
forall a.
HsMatchContext GhcRn
-> LPat GhcRn -> TcM a -> TcM ((LPat GhcTc, a), Kind)
tcInferPat HsMatchContext GhcRn
forall p. HsMatchContext p
PatSyn LPat GhcRn
lpat          (TcM [Id] -> TcM ((LPat GhcTc, [Id]), Kind))
-> TcM [Id] -> TcM ((LPat GhcTc, [Id]), Kind)
forall a b. (a -> b) -> a -> b
$
               (Name -> IOEnv (Env TcGblEnv TcLclEnv) Id) -> [Name] -> TcM [Id]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Name -> IOEnv (Env TcGblEnv TcLclEnv) Id
tcLookupId [Name]
arg_names

       ; let ([Id]
ex_tvs, [Id]
prov_dicts) = LPat GhcTc -> ([Id], [Id])
tcCollectEx Located (Pat GhcTc)
LPat GhcTc
lpat'

             named_taus :: [(Name, Kind)]
named_taus = (Name
IdP GhcRn
name, Kind
pat_ty) (Name, Kind) -> [(Name, Kind)] -> [(Name, Kind)]
forall a. a -> [a] -> [a]
: (Id -> (Name, Kind)) -> [Id] -> [(Name, Kind)]
forall a b. (a -> b) -> [a] -> [b]
map Id -> (Name, Kind)
mk_named_tau [Id]
args
             mk_named_tau :: Id -> (Name, Kind)
mk_named_tau Id
arg
               = (Id -> Name
forall a. NamedThing a => a -> Name
getName Id
arg, [Id] -> Kind -> Kind
mkSpecForAllTys [Id]
ex_tvs (Id -> Kind
varType Id
arg))
               -- The mkSpecForAllTys is important (#14552), albeit
               -- slightly artificial (there is no variable with this funny type).
               -- We do not want to quantify over variable (alpha::k)
               -- that mention the existentially-bound type variables
               -- ex_tvs in its kind k.
               -- See Note [Type variables whose kind is captured]

       ; ([Id]
univ_tvs, [Id]
req_dicts, TcEvBinds
ev_binds, WantedConstraints
residual, Bool
_)
               <- TcLevel
-> InferMode
-> [TcIdSigInst]
-> [(Name, Kind)]
-> WantedConstraints
-> TcM ([Id], [Id], TcEvBinds, WantedConstraints, Bool)
simplifyInfer TcLevel
tclvl InferMode
NoRestrictions [] [(Name, Kind)]
named_taus WantedConstraints
wanted
       ; Bag EvBind
top_ev_binds <- TcM (Bag EvBind) -> TcM (Bag EvBind)
forall r. TcM r -> TcM r
checkNoErrs (WantedConstraints -> TcM (Bag EvBind)
simplifyTop WantedConstraints
residual)
       ; Bag EvBind
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a. Bag EvBind -> TcM a -> TcM a
addTopEvBinds Bag EvBind
top_ev_binds (TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv))
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a b. (a -> b) -> a -> b
$

    do { [Id]
prov_dicts <- (Id -> IOEnv (Env TcGblEnv TcLclEnv) Id) -> [Id] -> TcM [Id]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Id -> IOEnv (Env TcGblEnv TcLclEnv) Id
zonkId [Id]
prov_dicts
       ; let filtered_prov_dicts :: [Id]
filtered_prov_dicts = (Id -> Kind) -> [Id] -> [Id]
forall a. (a -> Kind) -> [a] -> [a]
mkMinimalBySCs Id -> Kind
evVarPred [Id]
prov_dicts
             -- Filtering: see Note [Remove redundant provided dicts]
             ([Kind]
prov_theta, [EvTerm]
prov_evs)
                 = [(Kind, EvTerm)] -> ([Kind], [EvTerm])
forall a b. [(a, b)] -> ([a], [b])
unzip ((Id -> Maybe (Kind, EvTerm)) -> [Id] -> [(Kind, EvTerm)]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe Id -> Maybe (Kind, EvTerm)
mkProvEvidence [Id]
filtered_prov_dicts)
             req_theta :: [Kind]
req_theta = (Id -> Kind) -> [Id] -> [Kind]
forall a b. (a -> b) -> [a] -> [b]
map Id -> Kind
evVarPred [Id]
req_dicts

       -- Report coercions that escape
       -- See Note [Coercions that escape]
       ; [Id]
args <- (Id -> IOEnv (Env TcGblEnv TcLclEnv) Id) -> [Id] -> TcM [Id]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Id -> IOEnv (Env TcGblEnv TcLclEnv) Id
zonkId [Id]
args
       ; let bad_args :: [(Id, DVarSet)]
bad_args = [ (Id
arg, DVarSet
bad_cos) | Id
arg <- [Id]
args [Id] -> [Id] -> [Id]
forall a. [a] -> [a] -> [a]
++ [Id]
prov_dicts
                              , let bad_cos :: DVarSet
bad_cos = (Id -> Bool) -> DVarSet -> DVarSet
filterDVarSet Id -> Bool
isId (DVarSet -> DVarSet) -> DVarSet -> DVarSet
forall a b. (a -> b) -> a -> b
$
                                              (Kind -> DVarSet
tyCoVarsOfTypeDSet (Id -> Kind
idType Id
arg))
                              , Bool -> Bool
not (DVarSet -> Bool
isEmptyDVarSet DVarSet
bad_cos) ]
       ; ((Id, DVarSet) -> TcRn ()) -> [(Id, DVarSet)] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Id, DVarSet) -> TcRn ()
dependentArgErr [(Id, DVarSet)]
bad_args

       ; String -> MsgDoc -> TcRn ()
traceTc String
"tcInferPatSynDecl }" (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ (Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
IdP GhcRn
name MsgDoc -> MsgDoc -> MsgDoc
$$ [Id] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [Id]
ex_tvs)
       ; Located Name
-> HsPatSynDir GhcRn
-> Bool
-> LPat GhcTc
-> ([VarBndr Id Specificity], [Kind], TcEvBinds, [Id])
-> ([VarBndr Id Specificity], [Kind], [Kind], [EvTerm])
-> ([LHsExpr GhcTc], [Kind])
-> Kind
-> [Name]
-> TcM (LHsBinds GhcTc, TcGblEnv)
tc_patsyn_finish Located Name
GenLocated SrcSpan (IdP GhcRn)
lname HsPatSynDir GhcRn
dir Bool
is_infix Located (Pat GhcTc)
LPat GhcTc
lpat'
                          (Specificity -> [Id] -> [VarBndr Id Specificity]
forall vis. vis -> [Id] -> [VarBndr Id vis]
mkTyVarBinders Specificity
InferredSpec [Id]
univ_tvs
                            , [Kind]
req_theta,  TcEvBinds
ev_binds, [Id]
req_dicts)
                          (Specificity -> [Id] -> [VarBndr Id Specificity]
forall vis. vis -> [Id] -> [VarBndr Id vis]
mkTyVarBinders Specificity
InferredSpec [Id]
ex_tvs
                            , [Id] -> [Kind]
mkTyVarTys [Id]
ex_tvs, [Kind]
prov_theta, [EvTerm]
prov_evs)
                          ((Id -> LHsExpr GhcTc) -> [Id] -> [LHsExpr GhcTc]
forall a b. (a -> b) -> [a] -> [b]
map Id -> LHsExpr GhcTc
forall (id :: Pass). IdP (GhcPass id) -> LHsExpr (GhcPass id)
nlHsVar [Id]
args, (Id -> Kind) -> [Id] -> [Kind]
forall a b. (a -> b) -> [a] -> [b]
map Id -> Kind
idType [Id]
args)
                          Kind
pat_ty [Name]
rec_fields } }

mkProvEvidence :: EvId -> Maybe (PredType, EvTerm)
-- See Note [Equality evidence in pattern synonyms]
mkProvEvidence :: Id -> Maybe (Kind, EvTerm)
mkProvEvidence Id
ev_id
  | EqPred EqRel
r Kind
ty1 Kind
ty2 <- Kind -> Pred
classifyPredType Kind
pred
  , let k1 :: Kind
k1 = HasDebugCallStack => Kind -> Kind
Kind -> Kind
tcTypeKind Kind
ty1
        k2 :: Kind
k2 = HasDebugCallStack => Kind -> Kind
Kind -> Kind
tcTypeKind Kind
ty2
        is_homo :: Bool
is_homo = Kind
k1 HasDebugCallStack => Kind -> Kind -> Bool
Kind -> Kind -> Bool
`tcEqType` Kind
k2
        homo_tys :: [Kind]
homo_tys   = [Kind
k1, Kind
ty1, Kind
ty2]
        hetero_tys :: [Kind]
hetero_tys = [Kind
k1, Kind
k2, Kind
ty1, Kind
ty2]
  = case EqRel
r of
      EqRel
ReprEq | Bool
is_homo
             -> (Kind, EvTerm) -> Maybe (Kind, EvTerm)
forall a. a -> Maybe a
Just ( Class -> [Kind] -> Kind
mkClassPred Class
coercibleClass    [Kind]
homo_tys
                     , DataCon -> [Kind] -> [EvExpr] -> EvTerm
evDataConApp DataCon
coercibleDataCon [Kind]
homo_tys [EvExpr]
eq_con_args )
             | Bool
otherwise -> Maybe (Kind, EvTerm)
forall a. Maybe a
Nothing
      EqRel
NomEq  | Bool
is_homo
             -> (Kind, EvTerm) -> Maybe (Kind, EvTerm)
forall a. a -> Maybe a
Just ( Class -> [Kind] -> Kind
mkClassPred Class
eqClass    [Kind]
homo_tys
                     , DataCon -> [Kind] -> [EvExpr] -> EvTerm
evDataConApp DataCon
eqDataCon [Kind]
homo_tys [EvExpr]
eq_con_args )
             | Bool
otherwise
             -> (Kind, EvTerm) -> Maybe (Kind, EvTerm)
forall a. a -> Maybe a
Just ( Class -> [Kind] -> Kind
mkClassPred Class
heqClass    [Kind]
hetero_tys
                     , DataCon -> [Kind] -> [EvExpr] -> EvTerm
evDataConApp DataCon
heqDataCon [Kind]
hetero_tys [EvExpr]
eq_con_args )

  | Bool
otherwise
  = (Kind, EvTerm) -> Maybe (Kind, EvTerm)
forall a. a -> Maybe a
Just (Kind
pred, EvExpr -> EvTerm
EvExpr (Id -> EvExpr
evId Id
ev_id))
  where
    pred :: Kind
pred = Id -> Kind
evVarPred Id
ev_id
    eq_con_args :: [EvExpr]
eq_con_args = [Id -> EvExpr
evId Id
ev_id]

dependentArgErr :: (Id, DTyCoVarSet) -> TcM ()
-- See Note [Coercions that escape]
dependentArgErr :: (Id, DVarSet) -> TcRn ()
dependentArgErr (Id
arg, DVarSet
bad_cos)
  = MsgDoc -> TcRn ()
addErrTc (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    [MsgDoc] -> MsgDoc
vcat [ String -> MsgDoc
text String
"Iceland Jack!  Iceland Jack! Stop torturing me!"
         , MsgDoc -> Int -> MsgDoc -> MsgDoc
hang (String -> MsgDoc
text String
"Pattern-bound variable")
              Int
2 (Id -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Id
arg MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
dcolon MsgDoc -> MsgDoc -> MsgDoc
<+> Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr (Id -> Kind
idType Id
arg))
         , Int -> MsgDoc -> MsgDoc
nest Int
2 (MsgDoc -> MsgDoc) -> MsgDoc -> MsgDoc
forall a b. (a -> b) -> a -> b
$
           MsgDoc -> Int -> MsgDoc -> MsgDoc
hang (String -> MsgDoc
text String
"has a type that mentions pattern-bound coercion"
                 MsgDoc -> MsgDoc -> MsgDoc
<> [Id] -> MsgDoc
forall a. [a] -> MsgDoc
plural [Id]
bad_co_list MsgDoc -> MsgDoc -> MsgDoc
<> MsgDoc
colon)
              Int
2 ((Id -> MsgDoc) -> [Id] -> MsgDoc
forall a. (a -> MsgDoc) -> [a] -> MsgDoc
pprWithCommas Id -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [Id]
bad_co_list)
         , String -> MsgDoc
text String
"Hint: use -fprint-explicit-coercions to see the coercions"
         , String -> MsgDoc
text String
"Probable fix: add a pattern signature" ]
  where
    bad_co_list :: [Id]
bad_co_list = DVarSet -> [Id]
dVarSetElems DVarSet
bad_cos

{- Note [Type variables whose kind is captured]
~~-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
  data AST a = Sym [a]
  class Prj s where { prj :: [a] -> Maybe (s a) }
  pattern P x <= Sym (prj -> Just x)

Here we get a matcher with this type
  $mP :: forall s a. Prj s => AST a -> (s a -> r) -> r -> r

No problem.  But note that 's' is not fixed by the type of the
pattern (AST a), nor is it existentially bound.  It's really only
fixed by the type of the continuation.

#14552 showed that this can go wrong if the kind of 's' mentions
existentially bound variables.  We obviously can't make a type like
  $mP :: forall (s::k->*) a. Prj s => AST a -> (forall k. s a -> r)
                                   -> r -> r
But neither is 's' itself existentially bound, so the forall (s::k->*)
can't go in the inner forall either.  (What would the matcher apply
the continuation to?)

Solution: do not quantiify over any unification variable whose kind
mentions the existentials.  We can conveniently do that by making the
"taus" passed to simplifyInfer look like
   forall ex_tvs. arg_ty

After that, Note [Naughty quantification candidates] in GHC.Tc.Utils.TcMType takes
over and errors.

Note [Remove redundant provided dicts]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Recall that
   HRefl :: forall k1 k2 (a1:k1) (a2:k2). (k1 ~ k2, a1 ~ a2)
                                       => a1 :~~: a2
(NB: technically the (k1~k2) existential dictionary is not necessary,
but it's there at the moment.)

Now consider (#14394):
   pattern Foo = HRefl
in a non-poly-kinded module.  We don't want to get
    pattern Foo :: () => (* ~ *, b ~ a) => a :~~: b
with that redundant (* ~ *).  We'd like to remove it; hence the call to
mkMinimalWithSCs.

Similarly consider
  data S a where { MkS :: Ord a => a -> S a }
  pattern Bam x y <- (MkS (x::a), MkS (y::a)))

The pattern (Bam x y) binds two (Ord a) dictionaries, but we only
need one.  Again mkMimimalWithSCs removes the redundant one.

Note [Equality evidence in pattern synonyms]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
  data X a where
     MkX :: Eq a => [a] -> X (Maybe a)
  pattern P x = MkG x

Then there is a danger that GHC will infer
  P :: forall a.  () =>
       forall b. (a ~# Maybe b, Eq b) => [b] -> X a

The 'builder' for P, which is called in user-code, will then
have type
  $bP :: forall a b. (a ~# Maybe b, Eq b) => [b] -> X a

and that is bad because (a ~# Maybe b) is not a predicate type
(see Note [Types for coercions, predicates, and evidence] in GHC.Core.TyCo.Rep
and is not implicitly instantiated.

So in mkProvEvidence we lift (a ~# b) to (a ~ b).  Tiresome, and
marginally less efficient, if the builder/martcher are not inlined.

See also Note [Lift equality constraints when quantifying] in GHC.Tc.Utils.TcType

Note [Coercions that escape]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#14507 showed an example where the inferred type of the matcher
for the pattern synonym was something like
   $mSO :: forall (r :: TYPE rep) kk (a :: k).
           TypeRep k a
           -> ((Bool ~ k) => TypeRep Bool (a |> co_a2sv) -> r)
           -> (Void# -> r)
           -> r

What is that co_a2sv :: Bool ~# *??  It was bound (via a superclass
selection) by the pattern being matched; and indeed it is implicit in
the context (Bool ~ k).  You could imagine trying to extract it like
this:
   $mSO :: forall (r :: TYPE rep) kk (a :: k).
           TypeRep k a
           -> ( co :: ((Bool :: *) ~ (k :: *)) =>
                  let co_a2sv = sc_sel co
                  in TypeRep Bool (a |> co_a2sv) -> r)
           -> (Void# -> r)
           -> r

But we simply don't allow that in types.  Maybe one day but not now.

How to detect this situation?  We just look for free coercion variables
in the types of any of the arguments to the matcher.  The error message
is not very helpful, but at least we don't get a Lint error.
-}

tcCheckPatSynDecl :: PatSynBind GhcRn GhcRn
                  -> TcPatSynInfo
                  -> TcM (LHsBinds GhcTc, TcGblEnv)
tcCheckPatSynDecl :: PatSynBind GhcRn GhcRn
-> TcPatSynInfo -> TcM (LHsBinds GhcTc, TcGblEnv)
tcCheckPatSynDecl psb :: PatSynBind GhcRn GhcRn
psb@PSB{ psb_id :: forall idL idR. PatSynBind idL idR -> Located (IdP idL)
psb_id = lname :: GenLocated SrcSpan (IdP GhcRn)
lname@(L SrcSpan
_ IdP GhcRn
name), psb_args :: forall idL idR.
PatSynBind idL idR -> HsPatSynDetails (Located (IdP idR))
psb_args = HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details
                         , psb_def :: forall idL idR. PatSynBind idL idR -> LPat idR
psb_def = LPat GhcRn
lpat, psb_dir :: forall idL idR. PatSynBind idL idR -> HsPatSynDir idR
psb_dir = HsPatSynDir GhcRn
dir }
                  TPSI{ patsig_implicit_bndrs :: TcPatSynInfo -> [VarBndr Id Specificity]
patsig_implicit_bndrs = [VarBndr Id Specificity]
implicit_bndrs
                      , patsig_univ_bndrs :: TcPatSynInfo -> [VarBndr Id Specificity]
patsig_univ_bndrs = [VarBndr Id Specificity]
explicit_univ_bndrs, patsig_prov :: TcPatSynInfo -> [Kind]
patsig_prov = [Kind]
prov_theta
                      , patsig_ex_bndrs :: TcPatSynInfo -> [VarBndr Id Specificity]
patsig_ex_bndrs   = [VarBndr Id Specificity]
explicit_ex_bndrs,   patsig_req :: TcPatSynInfo -> [Kind]
patsig_req  = [Kind]
req_theta
                      , patsig_body_ty :: TcPatSynInfo -> Kind
patsig_body_ty    = Kind
sig_body_ty }
  = Located Name
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a. Located Name -> TcM a -> TcM a
addPatSynCtxt Located Name
GenLocated SrcSpan (IdP GhcRn)
lname (TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv))
-> TcM (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall a b. (a -> b) -> a -> b
$
    do { let decl_arity :: Int
decl_arity = [Name] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Name]
arg_names
             ([Name]
arg_names, [Name]
rec_fields, Bool
is_infix) = HsPatSynDetails (Located Name) -> ([Name], [Name], Bool)
collectPatSynArgInfo HsPatSynDetails (Located Name)
HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details

       ; String -> MsgDoc -> TcRn ()
traceTc String
"tcCheckPatSynDecl" (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         [MsgDoc] -> MsgDoc
vcat [ [VarBndr Id Specificity] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [VarBndr Id Specificity]
implicit_bndrs, [VarBndr Id Specificity] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [VarBndr Id Specificity]
explicit_univ_bndrs, [Kind] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [Kind]
req_theta
              , [VarBndr Id Specificity] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [VarBndr Id Specificity]
explicit_ex_bndrs, [Kind] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [Kind]
prov_theta, Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Kind
sig_body_ty ]

       ; ([Scaled Kind]
arg_tys, Kind
pat_ty) <- case Int -> Kind -> Either Int ([Scaled Kind], Kind)
tcSplitFunTysN Int
decl_arity Kind
sig_body_ty of
                                 Right ([Scaled Kind], Kind)
stuff  -> ([Scaled Kind], Kind)
-> IOEnv (Env TcGblEnv TcLclEnv) ([Scaled Kind], Kind)
forall (m :: * -> *) a. Monad m => a -> m a
return ([Scaled Kind], Kind)
stuff
                                 Left Int
missing -> Name
-> Int
-> Int
-> IOEnv (Env TcGblEnv TcLclEnv) ([Scaled Kind], Kind)
forall a. Name -> Int -> Int -> TcM a
wrongNumberOfParmsErr Name
IdP GhcRn
name Int
decl_arity Int
missing

       -- Complain about:  pattern P :: () => forall x. x -> P x
       -- The existential 'x' should not appear in the result type
       -- Can't check this until we know P's arity
       ; let bad_tvs :: [Id]
bad_tvs = (Id -> Bool) -> [Id] -> [Id]
forall a. (a -> Bool) -> [a] -> [a]
filter (Id -> VarSet -> Bool
`elemVarSet` Kind -> VarSet
tyCoVarsOfType Kind
pat_ty) ([Id] -> [Id]) -> [Id] -> [Id]
forall a b. (a -> b) -> a -> b
$ [VarBndr Id Specificity] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Id Specificity]
explicit_ex_bndrs
       ; Bool -> MsgDoc -> TcRn ()
checkTc ([Id] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Id]
bad_tvs) (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         MsgDoc -> Int -> MsgDoc -> MsgDoc
hang ([MsgDoc] -> MsgDoc
sep [ String -> MsgDoc
text String
"The result type of the signature for" MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc -> MsgDoc
quotes (Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
IdP GhcRn
name) MsgDoc -> MsgDoc -> MsgDoc
<> MsgDoc
comma
                   , String -> MsgDoc
text String
"namely" MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc -> MsgDoc
quotes (Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Kind
pat_ty) ])
            Int
2 (String -> MsgDoc
text String
"mentions existential type variable" MsgDoc -> MsgDoc -> MsgDoc
<> [Id] -> MsgDoc
forall a. [a] -> MsgDoc
plural [Id]
bad_tvs
               MsgDoc -> MsgDoc -> MsgDoc
<+> [Id] -> MsgDoc
forall a. Outputable a => [a] -> MsgDoc
pprQuotedList [Id]
bad_tvs)

         -- See Note [The pattern-synonym signature splitting rule] in GHC.Tc.Gen.Sig
       ; let univ_fvs :: VarSet
univ_fvs = VarSet -> VarSet
closeOverKinds (VarSet -> VarSet) -> VarSet -> VarSet
forall a b. (a -> b) -> a -> b
$
                        ([Kind] -> VarSet
tyCoVarsOfTypes (Kind
pat_ty Kind -> [Kind] -> [Kind]
forall a. a -> [a] -> [a]
: [Kind]
req_theta) VarSet -> [Id] -> VarSet
`extendVarSetList` ([VarBndr Id Specificity] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Id Specificity]
explicit_univ_bndrs))
             ([VarBndr Id Specificity]
extra_univ, [VarBndr Id Specificity]
extra_ex) = (VarBndr Id Specificity -> Bool)
-> [VarBndr Id Specificity]
-> ([VarBndr Id Specificity], [VarBndr Id Specificity])
forall a. (a -> Bool) -> [a] -> ([a], [a])
partition ((Id -> VarSet -> Bool
`elemVarSet` VarSet
univ_fvs) (Id -> Bool)
-> (VarBndr Id Specificity -> Id) -> VarBndr Id Specificity -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. VarBndr Id Specificity -> Id
forall tv argf. VarBndr tv argf -> tv
binderVar) [VarBndr Id Specificity]
implicit_bndrs
             univ_bndrs :: [VarBndr Id Specificity]
univ_bndrs = [VarBndr Id Specificity]
extra_univ [VarBndr Id Specificity]
-> [VarBndr Id Specificity] -> [VarBndr Id Specificity]
forall a. [a] -> [a] -> [a]
++ [VarBndr Id Specificity]
explicit_univ_bndrs
             ex_bndrs :: [VarBndr Id Specificity]
ex_bndrs   = [VarBndr Id Specificity]
extra_ex   [VarBndr Id Specificity]
-> [VarBndr Id Specificity] -> [VarBndr Id Specificity]
forall a. [a] -> [a] -> [a]
++ [VarBndr Id Specificity]
explicit_ex_bndrs
             univ_tvs :: [Id]
univ_tvs   = [VarBndr Id Specificity] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Id Specificity]
univ_bndrs
             ex_tvs :: [Id]
ex_tvs     = [VarBndr Id Specificity] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Id Specificity]
ex_bndrs

       -- Right!  Let's check the pattern against the signature
       -- See Note [Checking against a pattern signature]
       ; [Id]
req_dicts <- [Kind] -> TcM [Id]
newEvVars [Kind]
req_theta
       ; (TcLevel
tclvl, WantedConstraints
wanted, (Located (Pat GhcTc)
lpat', ([Id]
ex_tvs', [EvTerm]
prov_dicts, [LHsExpr GhcTc]
args'))) <-
           ASSERT2( equalLength arg_names arg_tys, ppr name $$ ppr arg_names $$ ppr arg_tys )
           TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (TcLevel, WantedConstraints,
      (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc])))
forall a. TcM a -> TcM (TcLevel, WantedConstraints, a)
pushLevelAndCaptureConstraints   (TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      (TcLevel, WantedConstraints,
       (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))))
-> TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (TcLevel, WantedConstraints,
      (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc])))
forall a b. (a -> b) -> a -> b
$
           [Id]
-> TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
-> TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
forall r. [Id] -> TcM r -> TcM r
tcExtendTyVarEnv [Id]
univ_tvs        (TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
 -> TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc])))
-> TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
-> TcM (Located (Pat GhcTc), ([Id], [EvTerm], [LHsExpr GhcTc]))
forall a b. (a -> b) -> a -> b
$
           HsMatchContext GhcRn
-> LPat GhcRn
-> Scaled Kind
-> TcM ([Id], [EvTerm], [LHsExpr GhcTc])
-> TcM (LPat GhcTc, ([Id], [EvTerm], [LHsExpr GhcTc]))
forall a.
HsMatchContext GhcRn
-> LPat GhcRn -> Scaled Kind -> TcM a -> TcM (LPat GhcTc, a)
tcCheckPat HsMatchContext GhcRn
forall p. HsMatchContext p
PatSyn LPat GhcRn
lpat (Kind -> Scaled Kind
forall a. a -> Scaled a
unrestricted Kind
pat_ty)   (TcM ([Id], [EvTerm], [LHsExpr GhcTc])
 -> TcM (LPat GhcTc, ([Id], [EvTerm], [LHsExpr GhcTc])))
-> TcM ([Id], [EvTerm], [LHsExpr GhcTc])
-> TcM (LPat GhcTc, ([Id], [EvTerm], [LHsExpr GhcTc]))
forall a b. (a -> b) -> a -> b
$
           do { let in_scope :: InScopeSet
in_scope    = VarSet -> InScopeSet
mkInScopeSet ([Id] -> VarSet
mkVarSet [Id]
univ_tvs)
                    empty_subst :: TCvSubst
empty_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst InScopeSet
in_scope
              ; (TCvSubst
subst, [Id]
ex_tvs') <- (TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id))
-> TCvSubst
-> [Id]
-> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, [Id])
forall (m :: * -> *) acc x y.
Monad m =>
(acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
mapAccumLM TCvSubst -> Id -> IOEnv (Env TcGblEnv TcLclEnv) (TCvSubst, Id)
newMetaTyVarX TCvSubst
empty_subst [Id]
ex_tvs
                    -- newMetaTyVarX: see the "Existential type variables"
                    -- part of Note [Checking against a pattern signature]
              ; String -> MsgDoc -> TcRn ()
traceTc String
"tcpatsyn1" ([MsgDoc] -> MsgDoc
vcat [ Id -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Id
v MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
dcolon MsgDoc -> MsgDoc -> MsgDoc
<+> Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr (Id -> Kind
tyVarKind Id
v) | Id
v <- [Id]
ex_tvs])
              ; String -> MsgDoc -> TcRn ()
traceTc String
"tcpatsyn2" ([MsgDoc] -> MsgDoc
vcat [ Id -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Id
v MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
dcolon MsgDoc -> MsgDoc -> MsgDoc
<+> Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr (Id -> Kind
tyVarKind Id
v) | Id
v <- [Id]
ex_tvs'])
              ; let prov_theta' :: [Kind]
prov_theta' = HasCallStack => TCvSubst -> [Kind] -> [Kind]
TCvSubst -> [Kind] -> [Kind]
substTheta TCvSubst
subst [Kind]
prov_theta
                  -- Add univ_tvs to the in_scope set to
                  -- satisfy the substitution invariant. There's no need to
                  -- add 'ex_tvs' as they are already in the domain of the
                  -- substitution.
                  -- See also Note [The substitution invariant] in GHC.Core.TyCo.Subst.
              ; [EvTerm]
prov_dicts <- (Kind -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm)
-> [Kind] -> IOEnv (Env TcGblEnv TcLclEnv) [EvTerm]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (CtOrigin -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) EvTerm
emitWanted (PatSynBind GhcRn GhcRn -> CtOrigin
ProvCtxtOrigin PatSynBind GhcRn GhcRn
psb)) [Kind]
prov_theta'
              ; [LHsExpr GhcTc]
args'      <- (Name -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) (LHsExpr GhcTc))
-> [Name]
-> [Kind]
-> IOEnv (Env TcGblEnv TcLclEnv) [LHsExpr GhcTc]
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m [c]
zipWithM (TCvSubst
-> Name -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) (LHsExpr GhcTc)
tc_arg TCvSubst
subst) [Name]
arg_names ((Scaled Kind -> Kind) -> [Scaled Kind] -> [Kind]
forall a b. (a -> b) -> [a] -> [b]
map Scaled Kind -> Kind
forall a. Scaled a -> a
scaledThing [Scaled Kind]
arg_tys)
              ; ([Id], [EvTerm], [LHsExpr GhcTc])
-> TcM ([Id], [EvTerm], [LHsExpr GhcTc])
forall (m :: * -> *) a. Monad m => a -> m a
return ([Id]
ex_tvs', [EvTerm]
prov_dicts, [LHsExpr GhcTc]
args') }

       ; let skol_info :: SkolemInfo
skol_info = UserTypeCtxt -> Kind -> [(Name, Id)] -> SkolemInfo
SigSkol (Name -> UserTypeCtxt
PatSynCtxt Name
IdP GhcRn
name) Kind
pat_ty []
                         -- The type here is a bit bogus, but we do not print
                         -- the type for PatSynCtxt, so it doesn't matter
                         -- See Note [Skolem info for pattern synonyms] in "GHC.Tc.Types.Origin"
       ; (Bag Implication
implics, TcEvBinds
ev_binds) <- TcLevel
-> SkolemInfo
-> [Id]
-> [Id]
-> WantedConstraints
-> TcM (Bag Implication, TcEvBinds)
buildImplicationFor TcLevel
tclvl SkolemInfo
skol_info [Id]
univ_tvs [Id]
req_dicts WantedConstraints
wanted

       -- Solve the constraints now, because we are about to make a PatSyn,
       -- which should not contain unification variables and the like (#10997)
       ; Bag Implication -> TcRn ()
simplifyTopImplic Bag Implication
implics

       -- ToDo: in the bidirectional case, check that the ex_tvs' are all distinct
       -- Otherwise we may get a type error when typechecking the builder,
       -- when that should be impossible

       ; String -> MsgDoc -> TcRn ()
traceTc String
"tcCheckPatSynDecl }" (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
IdP GhcRn
name
       ; Located Name
-> HsPatSynDir GhcRn
-> Bool
-> LPat GhcTc
-> ([VarBndr Id Specificity], [Kind], TcEvBinds, [Id])
-> ([VarBndr Id Specificity], [Kind], [Kind], [EvTerm])
-> ([LHsExpr GhcTc], [Kind])
-> Kind
-> [Name]
-> TcM (LHsBinds GhcTc, TcGblEnv)
tc_patsyn_finish Located Name
GenLocated SrcSpan (IdP GhcRn)
lname HsPatSynDir GhcRn
dir Bool
is_infix Located (Pat GhcTc)
LPat GhcTc
lpat'
                          ([VarBndr Id Specificity]
univ_bndrs, [Kind]
req_theta, TcEvBinds
ev_binds, [Id]
req_dicts)
                          ([VarBndr Id Specificity]
ex_bndrs, [Id] -> [Kind]
mkTyVarTys [Id]
ex_tvs', [Kind]
prov_theta, [EvTerm]
prov_dicts)
                          ([LHsExpr GhcTc]
args', ((Scaled Kind -> Kind) -> [Scaled Kind] -> [Kind]
forall a b. (a -> b) -> [a] -> [b]
map Scaled Kind -> Kind
forall a. Scaled a -> a
scaledThing [Scaled Kind]
arg_tys))
                          Kind
pat_ty [Name]
rec_fields }
  where
    tc_arg :: TCvSubst -> Name -> Type -> TcM (LHsExpr GhcTc)
    tc_arg :: TCvSubst
-> Name -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) (LHsExpr GhcTc)
tc_arg TCvSubst
subst Name
arg_name Kind
arg_ty
      = do {   -- Look up the variable actually bound by lpat
               -- and check that it has the expected type
             Id
arg_id <- Name -> IOEnv (Env TcGblEnv TcLclEnv) Id
tcLookupId Name
arg_name
           ; HsWrapper
wrap <- UserTypeCtxt -> Kind -> Kind -> TcM HsWrapper
tcSubTypeSigma UserTypeCtxt
GenSigCtxt
                                    (Id -> Kind
idType Id
arg_id)
                                    (TCvSubst -> Kind -> Kind
substTyUnchecked TCvSubst
subst Kind
arg_ty)
                -- Why do we need tcSubType here?
                -- See Note [Pattern synonyms and higher rank types]
           ; LHsExpr GhcTc -> IOEnv (Env TcGblEnv TcLclEnv) (LHsExpr GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsWrapper -> LHsExpr GhcTc -> LHsExpr GhcTc
mkLHsWrap HsWrapper
wrap (LHsExpr GhcTc -> LHsExpr GhcTc) -> LHsExpr GhcTc -> LHsExpr GhcTc
forall a b. (a -> b) -> a -> b
$ IdP GhcTc -> LHsExpr GhcTc
forall (id :: Pass). IdP (GhcPass id) -> LHsExpr (GhcPass id)
nlHsVar Id
IdP GhcTc
arg_id) }

{- [Pattern synonyms and higher rank types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
  data T = MkT (forall a. a->a)

  pattern P :: (Int -> Int) -> T
  pattern P x <- MkT x

This should work.  But in the matcher we must match against MkT, and then
instantiate its argument 'x', to get a function of type (Int -> Int).
Equality is not enough!  #13752 was an example.


Note [The pattern-synonym signature splitting rule]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Given a pattern signature, we must split
     the kind-generalised variables, and
     the implicitly-bound variables
into universal and existential.  The rule is this
(see discussion on #11224):

     The universal tyvars are the ones mentioned in
          - univ_tvs: the user-specified (forall'd) universals
          - req_theta
          - res_ty
     The existential tyvars are all the rest

For example

   pattern P :: () => b -> T a
   pattern P x = ...

Here 'a' is universal, and 'b' is existential.  But there is a wrinkle:
how do we split the arg_tys from req_ty?  Consider

   pattern Q :: () => b -> S c -> T a
   pattern Q x = ...

This is an odd example because Q has only one syntactic argument, and
so presumably is defined by a view pattern matching a function.  But
it can happen (#11977, #12108).

We don't know Q's arity from the pattern signature, so we have to wait
until we see the pattern declaration itself before deciding res_ty is,
and hence which variables are existential and which are universal.

And that in turn is why TcPatSynInfo has a separate field,
patsig_implicit_bndrs, to capture the implicitly bound type variables,
because we don't yet know how to split them up.

It's a slight compromise, because it means we don't really know the
pattern synonym's real signature until we see its declaration.  So,
for example, in hs-boot file, we may need to think what to do...
(eg don't have any implicitly-bound variables).


Note [Checking against a pattern signature]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When checking the actual supplied pattern against the pattern synonym
signature, we need to be quite careful.

----- Provided constraints
Example

    data T a where
      MkT :: Ord a => a -> T a

    pattern P :: () => Eq a => a -> [T a]
    pattern P x = [MkT x]

We must check that the (Eq a) that P claims to bind (and to
make available to matches against P), is derivable from the
actual pattern.  For example:
    f (P (x::a)) = ...here (Eq a) should be available...
And yes, (Eq a) is derivable from the (Ord a) bound by P's rhs.

----- Existential type variables
Unusually, we instantiate the existential tyvars of the pattern with
*meta* type variables.  For example

    data S where
      MkS :: Eq a => [a] -> S

    pattern P :: () => Eq x => x -> S
    pattern P x <- MkS x

The pattern synonym conceals from its client the fact that MkS has a
list inside it.  The client just thinks it's a type 'x'.  So we must
unify x := [a] during type checking, and then use the instantiating type
[a] (called ex_tys) when building the matcher.  In this case we'll get

   $mP :: S -> (forall x. Ex x => x -> r) -> r -> r
   $mP x k = case x of
               MkS a (d:Eq a) (ys:[a]) -> let dl :: Eq [a]
                                              dl = $dfunEqList d
                                          in k [a] dl ys

All this applies when type-checking the /matching/ side of
a pattern synonym.  What about the /building/ side?

* For Unidirectional, there is no builder

* For ExplicitBidirectional, the builder is completely separate
  code, typechecked in tcPatSynBuilderBind

* For ImplicitBidirectional, the builder is still typechecked in
  tcPatSynBuilderBind, by converting the pattern to an expression and
  typechecking it.

  At one point, for ImplicitBidirectional I used TyVarTvs (instead of
  TauTvs) in tcCheckPatSynDecl.  But (a) strengthening the check here
  is redundant since tcPatSynBuilderBind does the job, (b) it was
  still incomplete (TyVarTvs can unify with each other), and (c) it
  didn't even work (#13441 was accepted with
  ExplicitBidirectional, but rejected if expressed in
  ImplicitBidirectional form.  Conclusion: trying to be too clever is
  a bad idea.
-}

collectPatSynArgInfo :: HsPatSynDetails (Located Name)
                     -> ([Name], [Name], Bool)
collectPatSynArgInfo :: HsPatSynDetails (Located Name) -> ([Name], [Name], Bool)
collectPatSynArgInfo HsPatSynDetails (Located Name)
details =
  case HsPatSynDetails (Located Name)
details of
    PrefixCon [Located Name]
names      -> ((Located Name -> Name) -> [Located Name] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map Located Name -> Name
forall l e. GenLocated l e -> e
unLoc [Located Name]
names, [], Bool
False)
    InfixCon Located Name
name1 Located Name
name2 -> ((Located Name -> Name) -> [Located Name] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map Located Name -> Name
forall l e. GenLocated l e -> e
unLoc [Located Name
name1, Located Name
name2], [], Bool
True)
    RecCon [RecordPatSynField (Located Name)]
names         -> ([Name]
vars, [Name]
sels, Bool
False)
                         where
                            ([Name]
vars, [Name]
sels) = [(Name, Name)] -> ([Name], [Name])
forall a b. [(a, b)] -> ([a], [b])
unzip ((RecordPatSynField (Located Name) -> (Name, Name))
-> [RecordPatSynField (Located Name)] -> [(Name, Name)]
forall a b. (a -> b) -> [a] -> [b]
map RecordPatSynField (Located Name) -> (Name, Name)
splitRecordPatSyn [RecordPatSynField (Located Name)]
names)
  where
    splitRecordPatSyn :: RecordPatSynField (Located Name)
                      -> (Name, Name)
    splitRecordPatSyn :: RecordPatSynField (Located Name) -> (Name, Name)
splitRecordPatSyn (RecordPatSynField
                       { recordPatSynPatVar :: forall a. RecordPatSynField a -> a
recordPatSynPatVar     = L SrcSpan
_ Name
patVar
                       , recordPatSynSelectorId :: forall a. RecordPatSynField a -> a
recordPatSynSelectorId = L SrcSpan
_ Name
selId })
      = (Name
patVar, Name
selId)

addPatSynCtxt :: Located Name -> TcM a -> TcM a
addPatSynCtxt :: forall a. Located Name -> TcM a -> TcM a
addPatSynCtxt (L SrcSpan
loc Name
name) TcM a
thing_inside
  = SrcSpan -> TcM a -> TcM a
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (TcM a -> TcM a) -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    MsgDoc -> TcM a -> TcM a
forall a. MsgDoc -> TcM a -> TcM a
addErrCtxt (String -> MsgDoc
text String
"In the declaration for pattern synonym"
                MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc -> MsgDoc
quotes (Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
name)) (TcM a -> TcM a) -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    TcM a
thing_inside

wrongNumberOfParmsErr :: Name -> Arity -> Arity -> TcM a
wrongNumberOfParmsErr :: forall a. Name -> Int -> Int -> TcM a
wrongNumberOfParmsErr Name
name Int
decl_arity Int
missing
  = MsgDoc -> TcM a
forall a. MsgDoc -> TcM a
failWithTc (MsgDoc -> TcM a) -> MsgDoc -> TcM a
forall a b. (a -> b) -> a -> b
$
    MsgDoc -> Int -> MsgDoc -> MsgDoc
hang (String -> MsgDoc
text String
"Pattern synonym" MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc -> MsgDoc
quotes (Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
name) MsgDoc -> MsgDoc -> MsgDoc
<+> PtrString -> MsgDoc
ptext (String -> PtrString
sLit String
"has")
          MsgDoc -> MsgDoc -> MsgDoc
<+> Int -> MsgDoc -> MsgDoc
speakNOf Int
decl_arity (String -> MsgDoc
text String
"argument"))
       Int
2 (String -> MsgDoc
text String
"but its type signature has" MsgDoc -> MsgDoc -> MsgDoc
<+> Int -> MsgDoc
int Int
missing MsgDoc -> MsgDoc -> MsgDoc
<+> String -> MsgDoc
text String
"fewer arrows")

-------------------------
-- Shared by both tcInferPatSyn and tcCheckPatSyn
tc_patsyn_finish :: Located Name      -- ^ PatSyn Name
                 -> HsPatSynDir GhcRn -- ^ PatSyn type (Uni/Bidir/ExplicitBidir)
                 -> Bool              -- ^ Whether infix
                 -> LPat GhcTc        -- ^ Pattern of the PatSyn
                 -> ([TcInvisTVBinder], [PredType], TcEvBinds, [EvVar])
                 -> ([TcInvisTVBinder], [TcType], [PredType], [EvTerm])
                 -> ([LHsExpr GhcTc], [TcType])  -- ^ Pattern arguments and types
                 -> TcType            -- ^ Pattern type
                 -> [Name]            -- ^ Selector names
                 -- ^ Whether fields, empty if not record PatSyn
                 -> TcM (LHsBinds GhcTc, TcGblEnv)
tc_patsyn_finish :: Located Name
-> HsPatSynDir GhcRn
-> Bool
-> LPat GhcTc
-> ([VarBndr Id Specificity], [Kind], TcEvBinds, [Id])
-> ([VarBndr Id Specificity], [Kind], [Kind], [EvTerm])
-> ([LHsExpr GhcTc], [Kind])
-> Kind
-> [Name]
-> TcM (LHsBinds GhcTc, TcGblEnv)
tc_patsyn_finish Located Name
lname HsPatSynDir GhcRn
dir Bool
is_infix LPat GhcTc
lpat'
                 ([VarBndr Id Specificity]
univ_tvs, [Kind]
req_theta, TcEvBinds
req_ev_binds, [Id]
req_dicts)
                 ([VarBndr Id Specificity]
ex_tvs,   [Kind]
ex_tys,    [Kind]
prov_theta,   [EvTerm]
prov_dicts)
                 ([LHsExpr GhcTc]
args, [Kind]
arg_tys)
                 Kind
pat_ty [Name]
field_labels
  = do { -- Zonk everything.  We are about to build a final PatSyn
         -- so there had better be no unification variables in there

         (ZonkEnv
ze, [VarBndr Id Specificity]
univ_tvs') <- [VarBndr Id Specificity] -> TcM (ZonkEnv, [VarBndr Id Specificity])
forall vis. [VarBndr Id vis] -> TcM (ZonkEnv, [VarBndr Id vis])
zonkTyVarBinders [VarBndr Id Specificity]
univ_tvs
       ; [Kind]
req_theta'      <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
req_theta
       ; (ZonkEnv
ze, [VarBndr Id Specificity]
ex_tvs')   <- ZonkEnv
-> [VarBndr Id Specificity]
-> TcM (ZonkEnv, [VarBndr Id Specificity])
forall vis.
ZonkEnv -> [VarBndr Id vis] -> TcM (ZonkEnv, [VarBndr Id vis])
zonkTyVarBindersX ZonkEnv
ze [VarBndr Id Specificity]
ex_tvs
       ; [Kind]
prov_theta'     <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
prov_theta
       ; Kind
pat_ty'         <- ZonkEnv -> Kind -> TcM Kind
zonkTcTypeToTypeX ZonkEnv
ze Kind
pat_ty
       ; [Kind]
arg_tys'        <- ZonkEnv -> [Kind] -> TcM [Kind]
zonkTcTypesToTypesX ZonkEnv
ze [Kind]
arg_tys

       ; let (TidyEnv
env1, [VarBndr Id Specificity]
univ_tvs) = TidyEnv
-> [VarBndr Id Specificity] -> (TidyEnv, [VarBndr Id Specificity])
forall vis.
TidyEnv -> [VarBndr Id vis] -> (TidyEnv, [VarBndr Id vis])
tidyTyCoVarBinders TidyEnv
emptyTidyEnv [VarBndr Id Specificity]
univ_tvs'
             (TidyEnv
env2, [VarBndr Id Specificity]
ex_tvs)   = TidyEnv
-> [VarBndr Id Specificity] -> (TidyEnv, [VarBndr Id Specificity])
forall vis.
TidyEnv -> [VarBndr Id vis] -> (TidyEnv, [VarBndr Id vis])
tidyTyCoVarBinders TidyEnv
env1 [VarBndr Id Specificity]
ex_tvs'
             req_theta :: [Kind]
req_theta  = TidyEnv -> [Kind] -> [Kind]
tidyTypes TidyEnv
env2 [Kind]
req_theta'
             prov_theta :: [Kind]
prov_theta = TidyEnv -> [Kind] -> [Kind]
tidyTypes TidyEnv
env2 [Kind]
prov_theta'
             arg_tys :: [Kind]
arg_tys    = TidyEnv -> [Kind] -> [Kind]
tidyTypes TidyEnv
env2 [Kind]
arg_tys'
             pat_ty :: Kind
pat_ty     = TidyEnv -> Kind -> Kind
tidyType  TidyEnv
env2 Kind
pat_ty'

       ; String -> MsgDoc -> TcRn ()
traceTc String
"tc_patsyn_finish {" (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
           Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr (Located Name -> Name
forall l e. GenLocated l e -> e
unLoc Located Name
lname) MsgDoc -> MsgDoc -> MsgDoc
$$ Pat GhcTc -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr (Located (Pat GhcTc) -> Pat GhcTc
forall l e. GenLocated l e -> e
unLoc Located (Pat GhcTc)
LPat GhcTc
lpat') MsgDoc -> MsgDoc -> MsgDoc
$$
           ([VarBndr Id Specificity], [Kind], TcEvBinds, [Id]) -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr ([VarBndr Id Specificity]
univ_tvs, [Kind]
req_theta, TcEvBinds
req_ev_binds, [Id]
req_dicts) MsgDoc -> MsgDoc -> MsgDoc
$$
           ([VarBndr Id Specificity], [Kind], [EvTerm]) -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr ([VarBndr Id Specificity]
ex_tvs, [Kind]
prov_theta, [EvTerm]
prov_dicts) MsgDoc -> MsgDoc -> MsgDoc
$$
           [LHsExpr GhcTc] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [LHsExpr GhcTc]
args MsgDoc -> MsgDoc -> MsgDoc
$$
           [Kind] -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [Kind]
arg_tys MsgDoc -> MsgDoc -> MsgDoc
$$
           Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Kind
pat_ty

       -- Make the 'matcher'
       ; ((Id, Bool)
matcher_id, LHsBinds GhcTc
matcher_bind) <- Located Name
-> LPat GhcTc
-> ([Id], [Kind], TcEvBinds, [Id])
-> ([Id], [Kind], [Kind], [EvTerm])
-> ([LHsExpr GhcTc], [Kind])
-> Kind
-> TcM ((Id, Bool), LHsBinds GhcTc)
tcPatSynMatcher Located Name
lname LPat GhcTc
lpat'
                                         ([VarBndr Id Specificity] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Id Specificity]
univ_tvs, [Kind]
req_theta, TcEvBinds
req_ev_binds, [Id]
req_dicts)
                                         ([VarBndr Id Specificity] -> [Id]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars [VarBndr Id Specificity]
ex_tvs, [Kind]
ex_tys, [Kind]
prov_theta, [EvTerm]
prov_dicts)
                                         ([LHsExpr GhcTc]
args, [Kind]
arg_tys)
                                         Kind
pat_ty

       -- Make the 'builder'
       ; Maybe (Id, Bool)
builder_id <- HsPatSynDir GhcRn
-> Located Name
-> [VarBndr Id Specificity]
-> [Kind]
-> [VarBndr Id Specificity]
-> [Kind]
-> [Kind]
-> Kind
-> TcM (Maybe (Id, Bool))
forall a.
HsPatSynDir a
-> Located Name
-> [VarBndr Id Specificity]
-> [Kind]
-> [VarBndr Id Specificity]
-> [Kind]
-> [Kind]
-> Kind
-> TcM (Maybe (Id, Bool))
mkPatSynBuilderId HsPatSynDir GhcRn
dir Located Name
lname
                                         [VarBndr Id Specificity]
univ_tvs [Kind]
req_theta
                                         [VarBndr Id Specificity]
ex_tvs   [Kind]
prov_theta
                                         [Kind]
arg_tys Kind
pat_ty

         -- TODO: Make this have the proper information
       ; let mkFieldLabel :: Name -> FieldLabel
mkFieldLabel Name
name = FieldLabel :: forall a. FieldLabelString -> Bool -> a -> FieldLbl a
FieldLabel { flLabel :: FieldLabelString
flLabel = OccName -> FieldLabelString
occNameFS (Name -> OccName
nameOccName Name
name)
                                            , flIsOverloaded :: Bool
flIsOverloaded = Bool
False
                                            , flSelector :: Name
flSelector = Name
name }
             field_labels' :: [FieldLabel]
field_labels' = (Name -> FieldLabel) -> [Name] -> [FieldLabel]
forall a b. (a -> b) -> [a] -> [b]
map Name -> FieldLabel
mkFieldLabel [Name]
field_labels


       -- Make the PatSyn itself
       ; let patSyn :: PatSyn
patSyn = Name
-> Bool
-> ([VarBndr Id Specificity], [Kind])
-> ([VarBndr Id Specificity], [Kind])
-> [Kind]
-> Kind
-> (Id, Bool)
-> Maybe (Id, Bool)
-> [FieldLabel]
-> PatSyn
mkPatSyn (Located Name -> Name
forall l e. GenLocated l e -> e
unLoc Located Name
lname) Bool
is_infix
                        ([VarBndr Id Specificity]
univ_tvs, [Kind]
req_theta)
                        ([VarBndr Id Specificity]
ex_tvs, [Kind]
prov_theta)
                        [Kind]
arg_tys
                        Kind
pat_ty
                        (Id, Bool)
matcher_id Maybe (Id, Bool)
builder_id
                        [FieldLabel]
field_labels'

       -- Selectors
       ; let rn_rec_sel_binds :: [(Id, LHsBind GhcRn)]
rn_rec_sel_binds = PatSyn -> [FieldLabel] -> [(Id, LHsBind GhcRn)]
mkPatSynRecSelBinds PatSyn
patSyn (PatSyn -> [FieldLabel]
patSynFieldLabels PatSyn
patSyn)
             tything :: TyThing
tything = ConLike -> TyThing
AConLike (PatSyn -> ConLike
PatSynCon PatSyn
patSyn)
       ; TcGblEnv
tcg_env <- [TyThing] -> TcM TcGblEnv -> TcM TcGblEnv
forall r. [TyThing] -> TcM r -> TcM r
tcExtendGlobalEnv [TyThing
tything] (TcM TcGblEnv -> TcM TcGblEnv) -> TcM TcGblEnv -> TcM TcGblEnv
forall a b. (a -> b) -> a -> b
$
                    [(Id, LHsBind GhcRn)] -> TcM TcGblEnv
tcRecSelBinds [(Id, LHsBind GhcRn)]
rn_rec_sel_binds

       ; String -> MsgDoc -> TcRn ()
traceTc String
"tc_patsyn_finish }" MsgDoc
empty
       ; (LHsBinds GhcTc, TcGblEnv) -> TcM (LHsBinds GhcTc, TcGblEnv)
forall (m :: * -> *) a. Monad m => a -> m a
return (LHsBinds GhcTc
matcher_bind, TcGblEnv
tcg_env) }

{-
************************************************************************
*                                                                      *
         Constructing the "matcher" Id and its binding
*                                                                      *
************************************************************************
-}

tcPatSynMatcher :: Located Name
                -> LPat GhcTc
                -> ([TcTyVar], ThetaType, TcEvBinds, [EvVar])
                -> ([TcTyVar], [TcType], ThetaType, [EvTerm])
                -> ([LHsExpr GhcTc], [TcType])
                -> TcType
                -> TcM ((Id, Bool), LHsBinds GhcTc)
-- See Note [Matchers and builders for pattern synonyms] in GHC.Core.PatSyn
tcPatSynMatcher :: Located Name
-> LPat GhcTc
-> ([Id], [Kind], TcEvBinds, [Id])
-> ([Id], [Kind], [Kind], [EvTerm])
-> ([LHsExpr GhcTc], [Kind])
-> Kind
-> TcM ((Id, Bool), LHsBinds GhcTc)
tcPatSynMatcher (L SrcSpan
loc Name
name) LPat GhcTc
lpat
                ([Id]
univ_tvs, [Kind]
req_theta, TcEvBinds
req_ev_binds, [Id]
req_dicts)
                ([Id]
ex_tvs, [Kind]
ex_tys, [Kind]
prov_theta, [EvTerm]
prov_dicts)
                ([LHsExpr GhcTc]
args, [Kind]
arg_tys) Kind
pat_ty
  = do { Name
rr_name <- OccName -> SrcSpan -> TcRnIf TcGblEnv TcLclEnv Name
newNameAt (String -> OccName
mkTyVarOcc String
"rep") SrcSpan
loc
       ; Name
tv_name <- OccName -> SrcSpan -> TcRnIf TcGblEnv TcLclEnv Name
newNameAt (String -> OccName
mkTyVarOcc String
"r")   SrcSpan
loc
       ; let rr_tv :: Id
rr_tv  = Name -> Kind -> Id
mkTyVar Name
rr_name Kind
runtimeRepTy
             rr :: Kind
rr     = Id -> Kind
mkTyVarTy Id
rr_tv
             res_tv :: Id
res_tv = Name -> Kind -> Id
mkTyVar Name
tv_name (Kind -> Kind
tYPE Kind
rr)
             res_ty :: Kind
res_ty = Id -> Kind
mkTyVarTy Id
res_tv
             is_unlifted :: Bool
is_unlifted = [LHsExpr GhcTc] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [LHsExpr GhcTc]
args Bool -> Bool -> Bool
&& [EvTerm] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [EvTerm]
prov_dicts
             ([LHsExpr GhcTc]
cont_args, [Kind]
cont_arg_tys)
               | Bool
is_unlifted = ([IdP GhcTc -> LHsExpr GhcTc
forall (id :: Pass). IdP (GhcPass id) -> LHsExpr (GhcPass id)
nlHsVar Id
IdP GhcTc
voidPrimId], [Kind
voidPrimTy])
               | Bool
otherwise   = ([LHsExpr GhcTc]
args,                 [Kind]
arg_tys)
             cont_ty :: Kind
cont_ty = [Id] -> [Kind] -> Kind -> Kind
mkInfSigmaTy [Id]
ex_tvs [Kind]
prov_theta (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                       [Kind] -> Kind -> Kind
mkVisFunTysMany [Kind]
cont_arg_tys Kind
res_ty

             fail_ty :: Kind
fail_ty  = Kind -> Kind -> Kind
mkVisFunTyMany Kind
voidPrimTy Kind
res_ty

       ; Name
matcher_name <- Name -> (OccName -> OccName) -> TcRnIf TcGblEnv TcLclEnv Name
forall m n. Name -> (OccName -> OccName) -> TcRnIf m n Name
newImplicitBinder Name
name OccName -> OccName
mkMatcherOcc
       ; Id
scrutinee    <- FieldLabelString
-> Kind -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) Id
forall gbl lcl.
FieldLabelString -> Kind -> Kind -> TcRnIf gbl lcl Id
newSysLocalId (String -> FieldLabelString
fsLit String
"scrut") Kind
Many Kind
pat_ty
       ; Id
cont         <- FieldLabelString
-> Kind -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) Id
forall gbl lcl.
FieldLabelString -> Kind -> Kind -> TcRnIf gbl lcl Id
newSysLocalId (String -> FieldLabelString
fsLit String
"cont")  Kind
Many Kind
cont_ty
       ; Id
fail         <- FieldLabelString
-> Kind -> Kind -> IOEnv (Env TcGblEnv TcLclEnv) Id
forall gbl lcl.
FieldLabelString -> Kind -> Kind -> TcRnIf gbl lcl Id
newSysLocalId (String -> FieldLabelString
fsLit String
"fail")  Kind
Many Kind
fail_ty

       ; DynFlags
dflags       <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       ; let matcher_tau :: Kind
matcher_tau   = [Kind] -> Kind -> Kind
mkVisFunTysMany [Kind
pat_ty, Kind
cont_ty, Kind
fail_ty] Kind
res_ty
             matcher_sigma :: Kind
matcher_sigma = [Id] -> [Kind] -> Kind -> Kind
mkInfSigmaTy (Id
rr_tvId -> [Id] -> [Id]
forall a. a -> [a] -> [a]
:Id
res_tvId -> [Id] -> [Id]
forall a. a -> [a] -> [a]
:[Id]
univ_tvs) [Kind]
req_theta Kind
matcher_tau
             matcher_id :: Id
matcher_id    = Name -> Kind -> Id
mkExportedVanillaId Name
matcher_name Kind
matcher_sigma
                             -- See Note [Exported LocalIds] in GHC.Types.Id

             inst_wrap :: HsWrapper
inst_wrap = [EvTerm] -> HsWrapper
mkWpEvApps [EvTerm]
prov_dicts HsWrapper -> HsWrapper -> HsWrapper
<.> [Kind] -> HsWrapper
mkWpTyApps [Kind]
ex_tys
             cont' :: LHsExpr GhcTc
cont' = (LHsExpr GhcTc -> LHsExpr GhcTc -> LHsExpr GhcTc)
-> LHsExpr GhcTc -> [LHsExpr GhcTc] -> LHsExpr GhcTc
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' LHsExpr GhcTc -> LHsExpr GhcTc -> LHsExpr GhcTc
forall (id :: Pass).
IsPass id =>
LHsExpr (GhcPass id)
-> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)
nlHsApp (HsWrapper -> LHsExpr GhcTc -> LHsExpr GhcTc
mkLHsWrap HsWrapper
inst_wrap (IdP GhcTc -> LHsExpr GhcTc
forall (id :: Pass). IdP (GhcPass id) -> LHsExpr (GhcPass id)
nlHsVar Id
IdP GhcTc
cont)) [LHsExpr GhcTc]
cont_args

             fail' :: LHsExpr GhcTc
fail' = IdP GhcTc -> [LHsExpr GhcTc] -> LHsExpr GhcTc
forall (id :: Pass).
IsPass id =>
IdP (GhcPass id) -> [LHsExpr (GhcPass id)] -> LHsExpr (GhcPass id)
nlHsApps Id
IdP GhcTc
fail [IdP GhcTc -> LHsExpr GhcTc
forall (id :: Pass). IdP (GhcPass id) -> LHsExpr (GhcPass id)
nlHsVar Id
IdP GhcTc
voidPrimId]

             args :: [Located (Pat GhcTc)]
args = (Id -> Located (Pat GhcTc)) -> [Id] -> [Located (Pat GhcTc)]
forall a b. (a -> b) -> [a] -> [b]
map Id -> Located (Pat GhcTc)
forall (id :: Pass). IdP (GhcPass id) -> LPat (GhcPass id)
nlVarPat [Id
scrutinee, Id
cont, Id
fail]
             lwpat :: Located (Pat GhcTc)
lwpat = Pat GhcTc -> Located (Pat GhcTc)
forall e. e -> Located e
noLoc (Pat GhcTc -> Located (Pat GhcTc))
-> Pat GhcTc -> Located (Pat GhcTc)
forall a b. (a -> b) -> a -> b
$ XWildPat GhcTc -> Pat GhcTc
forall p. XWildPat p -> Pat p
WildPat Kind
XWildPat GhcTc
pat_ty
             cases :: [LMatch GhcTc (LHsExpr GhcTc)]
cases = if DynFlags -> LPat GhcTc -> Bool
forall (p :: Pass).
OutputableBndrId p =>
DynFlags -> LPat (GhcPass p) -> Bool
isIrrefutableHsPat DynFlags
dflags LPat GhcTc
lpat
                     then [LPat GhcTc -> LHsExpr GhcTc -> LMatch GhcTc (LHsExpr GhcTc)
forall (p :: Pass) (body :: * -> *).
LPat (GhcPass p)
-> Located (body (GhcPass p))
-> LMatch (GhcPass p) (Located (body (GhcPass p)))
mkHsCaseAlt LPat GhcTc
lpat  LHsExpr GhcTc
cont']
                     else [LPat GhcTc -> LHsExpr GhcTc -> LMatch GhcTc (LHsExpr GhcTc)
forall (p :: Pass) (body :: * -> *).
LPat (GhcPass p)
-> Located (body (GhcPass p))
-> LMatch (GhcPass p) (Located (body (GhcPass p)))
mkHsCaseAlt LPat GhcTc
lpat  LHsExpr GhcTc
cont',
                           LPat GhcTc -> LHsExpr GhcTc -> LMatch GhcTc (LHsExpr GhcTc)
forall (p :: Pass) (body :: * -> *).
LPat (GhcPass p)
-> Located (body (GhcPass p))
-> LMatch (GhcPass p) (Located (body (GhcPass p)))
mkHsCaseAlt Located (Pat GhcTc)
LPat GhcTc
lwpat LHsExpr GhcTc
fail']
             body :: LHsExpr GhcTc
body = HsWrapper -> LHsExpr GhcTc -> LHsExpr GhcTc
mkLHsWrap (TcEvBinds -> HsWrapper
mkWpLet TcEvBinds
req_ev_binds) (LHsExpr GhcTc -> LHsExpr GhcTc) -> LHsExpr GhcTc -> LHsExpr GhcTc
forall a b. (a -> b) -> a -> b
$
                    SrcSpan -> HsExpr GhcTc -> LHsExpr GhcTc
forall l e. l -> e -> GenLocated l e
L (Located (Pat GhcTc) -> SrcSpan
forall l e. GenLocated l e -> l
getLoc Located (Pat GhcTc)
LPat GhcTc
lpat) (HsExpr GhcTc -> LHsExpr GhcTc) -> HsExpr GhcTc -> LHsExpr GhcTc
forall a b. (a -> b) -> a -> b
$
                    XCase GhcTc
-> LHsExpr GhcTc
-> MatchGroup GhcTc (LHsExpr GhcTc)
-> HsExpr GhcTc
forall p.
XCase p -> LHsExpr p -> MatchGroup p (LHsExpr p) -> HsExpr p
HsCase NoExtField
XCase GhcTc
noExtField (IdP GhcTc -> LHsExpr GhcTc
forall (id :: Pass). IdP (GhcPass id) -> LHsExpr (GhcPass id)
nlHsVar Id
IdP GhcTc
scrutinee) (MatchGroup GhcTc (LHsExpr GhcTc) -> HsExpr GhcTc)
-> MatchGroup GhcTc (LHsExpr GhcTc) -> HsExpr GhcTc
forall a b. (a -> b) -> a -> b
$
                    MG :: forall p body.
XMG p body
-> Located [LMatch p body] -> Origin -> MatchGroup p body
MG{ mg_alts :: Located [LMatch GhcTc (LHsExpr GhcTc)]
mg_alts = SrcSpan
-> [LMatch GhcTc (LHsExpr GhcTc)]
-> Located [LMatch GhcTc (LHsExpr GhcTc)]
forall l e. l -> e -> GenLocated l e
L (Located (Pat GhcTc) -> SrcSpan
forall l e. GenLocated l e -> l
getLoc Located (Pat GhcTc)
LPat GhcTc
lpat) [LMatch GhcTc (LHsExpr GhcTc)]
cases
                      , mg_ext :: XMG GhcTc (LHsExpr GhcTc)
mg_ext = [Scaled Kind] -> Kind -> MatchGroupTc
MatchGroupTc [Kind -> Scaled Kind
forall a. a -> Scaled a
unrestricted Kind
pat_ty] Kind
res_ty
                      , mg_origin :: Origin
mg_origin = Origin
Generated
                      }
             body' :: LHsExpr GhcTc
body' = HsExpr GhcTc -> LHsExpr GhcTc
forall e. e -> Located e
noLoc (HsExpr GhcTc -> LHsExpr GhcTc) -> HsExpr GhcTc -> LHsExpr GhcTc
forall a b. (a -> b) -> a -> b
$
                     XLam GhcTc -> MatchGroup GhcTc (LHsExpr GhcTc) -> HsExpr GhcTc
forall p. XLam p -> MatchGroup p (LHsExpr p) -> HsExpr p
HsLam NoExtField
XLam GhcTc
noExtField (MatchGroup GhcTc (LHsExpr GhcTc) -> HsExpr GhcTc)
-> MatchGroup GhcTc (LHsExpr GhcTc) -> HsExpr GhcTc
forall a b. (a -> b) -> a -> b
$
                     MG :: forall p body.
XMG p body
-> Located [LMatch p body] -> Origin -> MatchGroup p body
MG{ mg_alts :: Located [LMatch GhcTc (LHsExpr GhcTc)]
mg_alts = [LMatch GhcTc (LHsExpr GhcTc)]
-> Located [LMatch GhcTc (LHsExpr GhcTc)]
forall e. e -> Located e
noLoc [HsMatchContext (NoGhcTc GhcTc)
-> [LPat GhcTc] -> LHsExpr GhcTc -> LMatch GhcTc (LHsExpr GhcTc)
forall (p :: Pass) (body :: * -> *).
HsMatchContext (NoGhcTc (GhcPass p))
-> [LPat (GhcPass p)]
-> Located (body (GhcPass p))
-> LMatch (GhcPass p) (Located (body (GhcPass p)))
mkSimpleMatch HsMatchContext (NoGhcTc GhcTc)
forall p. HsMatchContext p
LambdaExpr
                                                        [Located (Pat GhcTc)]
[LPat GhcTc]
args LHsExpr GhcTc
body]
                       , mg_ext :: XMG GhcTc (LHsExpr GhcTc)
mg_ext = [Scaled Kind] -> Kind -> MatchGroupTc
MatchGroupTc ((Kind -> Scaled Kind) -> [Kind] -> [Scaled Kind]
forall a b. (a -> b) -> [a] -> [b]
map Kind -> Scaled Kind
forall a. a -> Scaled a
unrestricted [Kind
pat_ty, Kind
cont_ty, Kind
fail_ty]) Kind
res_ty
                       , mg_origin :: Origin
mg_origin = Origin
Generated
                       }
             match :: LMatch GhcTc (LHsExpr GhcTc)
match = HsMatchContext (NoGhcTc GhcTc)
-> [LPat GhcTc]
-> LHsExpr GhcTc
-> Located (HsLocalBinds GhcTc)
-> LMatch GhcTc (LHsExpr GhcTc)
forall (p :: Pass).
IsPass p =>
HsMatchContext (NoGhcTc (GhcPass p))
-> [LPat (GhcPass p)]
-> LHsExpr (GhcPass p)
-> Located (HsLocalBinds (GhcPass p))
-> LMatch (GhcPass p) (LHsExpr (GhcPass p))
mkMatch (GenLocated SrcSpan (IdP GhcRn) -> HsMatchContext GhcRn
forall p. LIdP p -> HsMatchContext p
mkPrefixFunRhs (SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc Name
name)) []
                             ([Id] -> [Id] -> LHsExpr GhcTc -> LHsExpr GhcTc
mkHsLams (Id
rr_tvId -> [Id] -> [Id]
forall a. a -> [a] -> [a]
:Id
res_tvId -> [Id] -> [Id]
forall a. a -> [a] -> [a]
:[Id]
univ_tvs)
                                       [Id]
req_dicts LHsExpr GhcTc
body')
                             (HsLocalBinds GhcTc -> Located (HsLocalBinds GhcTc)
forall e. e -> Located e
noLoc (XEmptyLocalBinds GhcTc GhcTc -> HsLocalBinds GhcTc
forall idL idR. XEmptyLocalBinds idL idR -> HsLocalBindsLR idL idR
EmptyLocalBinds NoExtField
XEmptyLocalBinds GhcTc GhcTc
noExtField))
             mg :: MatchGroup GhcTc (LHsExpr GhcTc)
             mg :: MatchGroup GhcTc (LHsExpr GhcTc)
mg = MG :: forall p body.
XMG p body
-> Located [LMatch p body] -> Origin -> MatchGroup p body
MG{ mg_alts :: Located [LMatch GhcTc (LHsExpr GhcTc)]
mg_alts = SrcSpan
-> [LMatch GhcTc (LHsExpr GhcTc)]
-> Located [LMatch GhcTc (LHsExpr GhcTc)]
forall l e. l -> e -> GenLocated l e
L (LMatch GhcTc (LHsExpr GhcTc) -> SrcSpan
forall l e. GenLocated l e -> l
getLoc LMatch GhcTc (LHsExpr GhcTc)
match) [LMatch GhcTc (LHsExpr GhcTc)
match]
                    , mg_ext :: XMG GhcTc (LHsExpr GhcTc)
mg_ext = [Scaled Kind] -> Kind -> MatchGroupTc
MatchGroupTc [] Kind
res_ty
                    , mg_origin :: Origin
mg_origin = Origin
Generated
                    }

       ; let bind :: HsBindLR GhcTc GhcTc
bind = FunBind :: forall idL idR.
XFunBind idL idR
-> Located (IdP idL)
-> MatchGroup idR (LHsExpr idR)
-> [Tickish Id]
-> HsBindLR idL idR
FunBind{ fun_id :: Located (IdP GhcTc)
fun_id = SrcSpan -> Id -> Located Id
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc Id
matcher_id
                           , fun_matches :: MatchGroup GhcTc (LHsExpr GhcTc)
fun_matches = MatchGroup GhcTc (LHsExpr GhcTc)
mg
                           , fun_ext :: XFunBind GhcTc GhcTc
fun_ext = XFunBind GhcTc GhcTc
HsWrapper
idHsWrapper
                           , fun_tick :: [Tickish Id]
fun_tick = [] }
             matcher_bind :: LHsBinds GhcTc
matcher_bind = GenLocated SrcSpan (HsBindLR GhcTc GhcTc) -> LHsBinds GhcTc
forall a. a -> Bag a
unitBag (HsBindLR GhcTc GhcTc -> GenLocated SrcSpan (HsBindLR GhcTc GhcTc)
forall e. e -> Located e
noLoc HsBindLR GhcTc GhcTc
bind)

       ; String -> MsgDoc -> TcRn ()
traceTc String
"tcPatSynMatcher" (Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
name MsgDoc -> MsgDoc -> MsgDoc
$$ Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr (Id -> Kind
idType Id
matcher_id))
       ; String -> MsgDoc -> TcRn ()
traceTc String
"tcPatSynMatcher" (LHsBinds GhcTc -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr LHsBinds GhcTc
matcher_bind)

       ; ((Id, Bool), LHsBinds GhcTc) -> TcM ((Id, Bool), LHsBinds GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return ((Id
matcher_id, Bool
is_unlifted), LHsBinds GhcTc
matcher_bind) }

mkPatSynRecSelBinds :: PatSyn
                    -> [FieldLabel]  -- ^ Visible field labels
                    -> [(Id, LHsBind GhcRn)]
mkPatSynRecSelBinds :: PatSyn -> [FieldLabel] -> [(Id, LHsBind GhcRn)]
mkPatSynRecSelBinds PatSyn
ps [FieldLabel]
fields
  = [ [ConLike] -> RecSelParent -> FieldLabel -> (Id, LHsBind GhcRn)
mkOneRecordSelector [PatSyn -> ConLike
PatSynCon PatSyn
ps] (PatSyn -> RecSelParent
RecSelPatSyn PatSyn
ps) FieldLabel
fld_lbl
    | FieldLabel
fld_lbl <- [FieldLabel]
fields ]

isUnidirectional :: HsPatSynDir a -> Bool
isUnidirectional :: forall a. HsPatSynDir a -> Bool
isUnidirectional HsPatSynDir a
Unidirectional          = Bool
True
isUnidirectional HsPatSynDir a
ImplicitBidirectional   = Bool
False
isUnidirectional ExplicitBidirectional{} = Bool
False

{-
************************************************************************
*                                                                      *
         Constructing the "builder" Id
*                                                                      *
************************************************************************
-}

mkPatSynBuilderId :: HsPatSynDir a -> Located Name
                  -> [InvisTVBinder] -> ThetaType
                  -> [InvisTVBinder] -> ThetaType
                  -> [Type] -> Type
                  -> TcM (Maybe (Id, Bool))
mkPatSynBuilderId :: forall a.
HsPatSynDir a
-> Located Name
-> [VarBndr Id Specificity]
-> [Kind]
-> [VarBndr Id Specificity]
-> [Kind]
-> [Kind]
-> Kind
-> TcM (Maybe (Id, Bool))
mkPatSynBuilderId HsPatSynDir a
dir (L SrcSpan
_ Name
name)
                  [VarBndr Id Specificity]
univ_bndrs [Kind]
req_theta [VarBndr Id Specificity]
ex_bndrs [Kind]
prov_theta
                  [Kind]
arg_tys Kind
pat_ty
  | HsPatSynDir a -> Bool
forall a. HsPatSynDir a -> Bool
isUnidirectional HsPatSynDir a
dir
  = Maybe (Id, Bool) -> TcM (Maybe (Id, Bool))
forall (m :: * -> *) a. Monad m => a -> m a
return Maybe (Id, Bool)
forall a. Maybe a
Nothing
  | Bool
otherwise
  = do { Name
builder_name <- Name -> (OccName -> OccName) -> TcRnIf TcGblEnv TcLclEnv Name
forall m n. Name -> (OccName -> OccName) -> TcRnIf m n Name
newImplicitBinder Name
name OccName -> OccName
mkBuilderOcc
       ; let theta :: [Kind]
theta          = [Kind]
req_theta [Kind] -> [Kind] -> [Kind]
forall a. [a] -> [a] -> [a]
++ [Kind]
prov_theta
             need_dummy_arg :: Bool
need_dummy_arg = HasDebugCallStack => Kind -> Bool
Kind -> Bool
isUnliftedType Kind
pat_ty Bool -> Bool -> Bool
&& [Kind] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Kind]
arg_tys Bool -> Bool -> Bool
&& [Kind] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Kind]
theta
             builder_sigma :: Kind
builder_sigma  = Bool -> Kind -> Kind
add_void Bool
need_dummy_arg (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                              [VarBndr Id Specificity] -> Kind -> Kind
mkInvisForAllTys [VarBndr Id Specificity]
univ_bndrs (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                              [VarBndr Id Specificity] -> Kind -> Kind
mkInvisForAllTys [VarBndr Id Specificity]
ex_bndrs (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                              [Kind] -> Kind -> Kind
mkPhiTy [Kind]
theta (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                              [Kind] -> Kind -> Kind
mkVisFunTysMany [Kind]
arg_tys (Kind -> Kind) -> Kind -> Kind
forall a b. (a -> b) -> a -> b
$
                              Kind
pat_ty
             builder_id :: Id
builder_id     = Name -> Kind -> Id
mkExportedVanillaId Name
builder_name Kind
builder_sigma
              -- See Note [Exported LocalIds] in GHC.Types.Id

             builder_id' :: Id
builder_id'    = HasDebugCallStack => (IdInfo -> IdInfo) -> Id -> Id
(IdInfo -> IdInfo) -> Id -> Id
modifyIdInfo (IdInfo -> Kind -> IdInfo
`setLevityInfoWithType` Kind
pat_ty) Id
builder_id

       ; Maybe (Id, Bool) -> TcM (Maybe (Id, Bool))
forall (m :: * -> *) a. Monad m => a -> m a
return ((Id, Bool) -> Maybe (Id, Bool)
forall a. a -> Maybe a
Just (Id
builder_id', Bool
need_dummy_arg)) }
  where

tcPatSynBuilderBind :: PatSynBind GhcRn GhcRn
                    -> TcM (LHsBinds GhcTc)
-- See Note [Matchers and builders for pattern synonyms] in GHC.Core.PatSyn
tcPatSynBuilderBind :: PatSynBind GhcRn GhcRn -> TcM (LHsBinds GhcTc)
tcPatSynBuilderBind (PSB { psb_id :: forall idL idR. PatSynBind idL idR -> Located (IdP idL)
psb_id = L SrcSpan
loc IdP GhcRn
name
                         , psb_def :: forall idL idR. PatSynBind idL idR -> LPat idR
psb_def = LPat GhcRn
lpat
                         , psb_dir :: forall idL idR. PatSynBind idL idR -> HsPatSynDir idR
psb_dir = HsPatSynDir GhcRn
dir
                         , psb_args :: forall idL idR.
PatSynBind idL idR -> HsPatSynDetails (Located (IdP idR))
psb_args = HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details })
  | HsPatSynDir GhcRn -> Bool
forall a. HsPatSynDir a -> Bool
isUnidirectional HsPatSynDir GhcRn
dir
  = LHsBinds GhcTc -> TcM (LHsBinds GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return LHsBinds GhcTc
forall a. Bag a
emptyBag

  | Left MsgDoc
why <- Either MsgDoc (MatchGroup GhcRn (LHsExpr GhcRn))
mb_match_group       -- Can't invert the pattern
  = SrcSpan -> TcM (LHsBinds GhcTc) -> TcM (LHsBinds GhcTc)
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (Located (Pat GhcRn) -> SrcSpan
forall l e. GenLocated l e -> l
getLoc Located (Pat GhcRn)
LPat GhcRn
lpat) (TcM (LHsBinds GhcTc) -> TcM (LHsBinds GhcTc))
-> TcM (LHsBinds GhcTc) -> TcM (LHsBinds GhcTc)
forall a b. (a -> b) -> a -> b
$ MsgDoc -> TcM (LHsBinds GhcTc)
forall a. MsgDoc -> TcM a
failWithTc (MsgDoc -> TcM (LHsBinds GhcTc)) -> MsgDoc -> TcM (LHsBinds GhcTc)
forall a b. (a -> b) -> a -> b
$
    [MsgDoc] -> MsgDoc
vcat [ MsgDoc -> Int -> MsgDoc -> MsgDoc
hang (String -> MsgDoc
text String
"Invalid right-hand side of bidirectional pattern synonym"
                 MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc -> MsgDoc
quotes (Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
IdP GhcRn
name) MsgDoc -> MsgDoc -> MsgDoc
<> MsgDoc
colon)
              Int
2 MsgDoc
why
         , String -> MsgDoc
text String
"RHS pattern:" MsgDoc -> MsgDoc -> MsgDoc
<+> Located (Pat GhcRn) -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Located (Pat GhcRn)
LPat GhcRn
lpat ]

  | Right MatchGroup GhcRn (LHsExpr GhcRn)
match_group <- Either MsgDoc (MatchGroup GhcRn (LHsExpr GhcRn))
mb_match_group  -- Bidirectional
  = do { PatSyn
patsyn <- Name -> TcM PatSyn
tcLookupPatSyn Name
IdP GhcRn
name
       ; case PatSyn -> Maybe (Id, Bool)
patSynBuilder PatSyn
patsyn of {
           Maybe (Id, Bool)
Nothing -> LHsBinds GhcTc -> TcM (LHsBinds GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return LHsBinds GhcTc
forall a. Bag a
emptyBag ;
             -- This case happens if we found a type error in the
             -- pattern synonym, recovered, and put a placeholder
             -- with patSynBuilder=Nothing in the environment

           Just (Id
builder_id, Bool
need_dummy_arg) ->  -- Normal case
    do { -- Bidirectional, so patSynBuilder returns Just
         let match_group' :: MatchGroup GhcRn (LHsExpr GhcRn)
match_group' | Bool
need_dummy_arg = MatchGroup GhcRn (LHsExpr GhcRn)
-> MatchGroup GhcRn (LHsExpr GhcRn)
add_dummy_arg MatchGroup GhcRn (LHsExpr GhcRn)
match_group
                          | Bool
otherwise      = MatchGroup GhcRn (LHsExpr GhcRn)
match_group

             bind :: HsBindLR GhcRn GhcRn
bind = FunBind :: forall idL idR.
XFunBind idL idR
-> Located (IdP idL)
-> MatchGroup idR (LHsExpr idR)
-> [Tickish Id]
-> HsBindLR idL idR
FunBind { fun_id :: GenLocated SrcSpan (IdP GhcRn)
fun_id      = SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc (Id -> Name
idName Id
builder_id)
                            , fun_matches :: MatchGroup GhcRn (LHsExpr GhcRn)
fun_matches = MatchGroup GhcRn (LHsExpr GhcRn)
match_group'
                            , fun_ext :: XFunBind GhcRn GhcRn
fun_ext     = NameSet
XFunBind GhcRn GhcRn
emptyNameSet
                            , fun_tick :: [Tickish Id]
fun_tick    = [] }

             sig :: TcIdSigInfo
sig = UserTypeCtxt -> Id -> TcIdSigInfo
completeSigFromId (Name -> UserTypeCtxt
PatSynCtxt Name
IdP GhcRn
name) Id
builder_id

       ; String -> MsgDoc -> TcRn ()
traceTc String
"tcPatSynBuilderBind {" (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         PatSyn -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr PatSyn
patsyn MsgDoc -> MsgDoc -> MsgDoc
$$ Id -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Id
builder_id MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
dcolon MsgDoc -> MsgDoc -> MsgDoc
<+> Kind -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr (Id -> Kind
idType Id
builder_id)
       ; (LHsBinds GhcTc
builder_binds, [Id]
_) <- TcPragEnv
-> TcIdSigInfo -> LHsBind GhcRn -> TcM (LHsBinds GhcTc, [Id])
tcPolyCheck TcPragEnv
emptyPragEnv TcIdSigInfo
sig (HsBindLR GhcRn GhcRn -> LHsBind GhcRn
forall e. e -> Located e
noLoc HsBindLR GhcRn GhcRn
bind)
       ; String -> MsgDoc -> TcRn ()
traceTc String
"tcPatSynBuilderBind }" (MsgDoc -> TcRn ()) -> MsgDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ LHsBinds GhcTc -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr LHsBinds GhcTc
builder_binds
       ; LHsBinds GhcTc -> TcM (LHsBinds GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return LHsBinds GhcTc
builder_binds } } }

#if __GLASGOW_HASKELL__ <= 810
  | otherwise = panic "tcPatSynBuilderBind"  -- Both cases dealt with
#endif
  where
    mb_match_group :: Either MsgDoc (MatchGroup GhcRn (LHsExpr GhcRn))
mb_match_group
       = case HsPatSynDir GhcRn
dir of
           ExplicitBidirectional MatchGroup GhcRn (LHsExpr GhcRn)
explicit_mg -> MatchGroup GhcRn (LHsExpr GhcRn)
-> Either MsgDoc (MatchGroup GhcRn (LHsExpr GhcRn))
forall a b. b -> Either a b
Right MatchGroup GhcRn (LHsExpr GhcRn)
explicit_mg
           HsPatSynDir GhcRn
ImplicitBidirectional -> (LHsExpr GhcRn -> MatchGroup GhcRn (LHsExpr GhcRn))
-> Either MsgDoc (LHsExpr GhcRn)
-> Either MsgDoc (MatchGroup GhcRn (LHsExpr GhcRn))
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap LHsExpr GhcRn -> MatchGroup GhcRn (LHsExpr GhcRn)
mk_mg (Name
-> [Located Name] -> LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
tcPatToExpr Name
IdP GhcRn
name [Located Name]
[GenLocated SrcSpan (IdP GhcRn)]
args LPat GhcRn
lpat)
           HsPatSynDir GhcRn
Unidirectional -> String -> Either MsgDoc (MatchGroup GhcRn (LHsExpr GhcRn))
forall a. String -> a
panic String
"tcPatSynBuilderBind"

    mk_mg :: LHsExpr GhcRn -> MatchGroup GhcRn (LHsExpr GhcRn)
    mk_mg :: LHsExpr GhcRn -> MatchGroup GhcRn (LHsExpr GhcRn)
mk_mg LHsExpr GhcRn
body = Origin
-> [LMatch GhcRn (LHsExpr GhcRn)]
-> MatchGroup GhcRn (LHsExpr GhcRn)
forall name (body :: * -> *).
(XMG name (Located (body name)) ~ NoExtField) =>
Origin
-> [LMatch name (Located (body name))]
-> MatchGroup name (Located (body name))
mkMatchGroup Origin
Generated [LMatch GhcRn (LHsExpr GhcRn)
builder_match]
          where
            builder_args :: [Located (Pat GhcRn)]
builder_args  = [SrcSpan -> Pat GhcRn -> Located (Pat GhcRn)
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc (XVarPat GhcRn -> GenLocated SrcSpan (IdP GhcRn) -> Pat GhcRn
forall p. XVarPat p -> Located (IdP p) -> Pat p
VarPat NoExtField
XVarPat GhcRn
noExtField (SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc Name
n))
                            | L SrcSpan
loc Name
n <- [Located Name]
[GenLocated SrcSpan (IdP GhcRn)]
args]
            builder_match :: LMatch GhcRn (LHsExpr GhcRn)
builder_match = HsMatchContext (NoGhcTc GhcRn)
-> [LPat GhcRn]
-> LHsExpr GhcRn
-> Located (HsLocalBinds GhcRn)
-> LMatch GhcRn (LHsExpr GhcRn)
forall (p :: Pass).
IsPass p =>
HsMatchContext (NoGhcTc (GhcPass p))
-> [LPat (GhcPass p)]
-> LHsExpr (GhcPass p)
-> Located (HsLocalBinds (GhcPass p))
-> LMatch (GhcPass p) (LHsExpr (GhcPass p))
mkMatch (GenLocated SrcSpan (IdP GhcRn) -> HsMatchContext GhcRn
forall p. LIdP p -> HsMatchContext p
mkPrefixFunRhs (SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc Name
IdP GhcRn
name))
                                    [Located (Pat GhcRn)]
[LPat GhcRn]
builder_args LHsExpr GhcRn
body
                                    (HsLocalBinds GhcRn -> Located (HsLocalBinds GhcRn)
forall e. e -> Located e
noLoc (XEmptyLocalBinds GhcRn GhcRn -> HsLocalBinds GhcRn
forall idL idR. XEmptyLocalBinds idL idR -> HsLocalBindsLR idL idR
EmptyLocalBinds NoExtField
XEmptyLocalBinds GhcRn GhcRn
noExtField))

    args :: [GenLocated SrcSpan (IdP GhcRn)]
args = case HsPatSynDetails (GenLocated SrcSpan (IdP GhcRn))
details of
              PrefixCon [GenLocated SrcSpan (IdP GhcRn)]
args     -> [GenLocated SrcSpan (IdP GhcRn)]
args
              InfixCon GenLocated SrcSpan (IdP GhcRn)
arg1 GenLocated SrcSpan (IdP GhcRn)
arg2 -> [GenLocated SrcSpan (IdP GhcRn)
arg1, GenLocated SrcSpan (IdP GhcRn)
arg2]
              RecCon [RecordPatSynField (GenLocated SrcSpan (IdP GhcRn))]
args        -> (RecordPatSynField (Located Name) -> Located Name)
-> [RecordPatSynField (Located Name)] -> [Located Name]
forall a b. (a -> b) -> [a] -> [b]
map RecordPatSynField (Located Name) -> Located Name
forall a. RecordPatSynField a -> a
recordPatSynPatVar [RecordPatSynField (Located Name)]
[RecordPatSynField (GenLocated SrcSpan (IdP GhcRn))]
args

    add_dummy_arg :: MatchGroup GhcRn (LHsExpr GhcRn)
                  -> MatchGroup GhcRn (LHsExpr GhcRn)
    add_dummy_arg :: MatchGroup GhcRn (LHsExpr GhcRn)
-> MatchGroup GhcRn (LHsExpr GhcRn)
add_dummy_arg mg :: MatchGroup GhcRn (LHsExpr GhcRn)
mg@(MG { mg_alts :: forall p body. MatchGroup p body -> Located [LMatch p body]
mg_alts =
                           (L SrcSpan
l [L SrcSpan
loc match :: Match GhcRn (LHsExpr GhcRn)
match@(Match { m_pats :: forall p body. Match p body -> [LPat p]
m_pats = [LPat GhcRn]
pats })]) })
      = MatchGroup GhcRn (LHsExpr GhcRn)
mg { mg_alts :: GenLocated SrcSpan [LMatch GhcRn (LHsExpr GhcRn)]
mg_alts = SrcSpan
-> [LMatch GhcRn (LHsExpr GhcRn)]
-> GenLocated SrcSpan [LMatch GhcRn (LHsExpr GhcRn)]
forall l e. l -> e -> GenLocated l e
L SrcSpan
l [SrcSpan
-> Match GhcRn (LHsExpr GhcRn) -> LMatch GhcRn (LHsExpr GhcRn)
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc (Match GhcRn (LHsExpr GhcRn)
match { m_pats :: [LPat GhcRn]
m_pats = Located (Pat GhcRn)
LPat GhcRn
nlWildPatName Located (Pat GhcRn)
-> [Located (Pat GhcRn)] -> [Located (Pat GhcRn)]
forall a. a -> [a] -> [a]
: [Located (Pat GhcRn)]
[LPat GhcRn]
pats })] }
    add_dummy_arg MatchGroup GhcRn (LHsExpr GhcRn)
other_mg = String -> MsgDoc -> MatchGroup GhcRn (LHsExpr GhcRn)
forall a. HasCallStack => String -> MsgDoc -> a
pprPanic String
"add_dummy_arg" (MsgDoc -> MatchGroup GhcRn (LHsExpr GhcRn))
-> MsgDoc -> MatchGroup GhcRn (LHsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$
                             MatchGroup GhcRn (LHsExpr GhcRn) -> MsgDoc
forall (idR :: Pass) body.
(OutputableBndrId idR, Outputable body) =>
MatchGroup (GhcPass idR) body -> MsgDoc
pprMatches MatchGroup GhcRn (LHsExpr GhcRn)
other_mg

tcPatSynBuilderOcc :: PatSyn -> TcM (HsExpr GhcTc, TcSigmaType)
-- monadic only for failure
tcPatSynBuilderOcc :: PatSyn -> TcM (HsExpr GhcTc, Kind)
tcPatSynBuilderOcc PatSyn
ps
  | Just (Id
builder_id, Bool
add_void_arg) <- Maybe (Id, Bool)
builder
  , let builder_expr :: HsExpr GhcTc
builder_expr = XConLikeOut GhcTc -> ConLike -> HsExpr GhcTc
forall p. XConLikeOut p -> ConLike -> HsExpr p
HsConLikeOut NoExtField
XConLikeOut GhcTc
noExtField (PatSyn -> ConLike
PatSynCon PatSyn
ps)
        builder_ty :: Kind
builder_ty   = Id -> Kind
idType Id
builder_id
  = (HsExpr GhcTc, Kind) -> TcM (HsExpr GhcTc, Kind)
forall (m :: * -> *) a. Monad m => a -> m a
return ((HsExpr GhcTc, Kind) -> TcM (HsExpr GhcTc, Kind))
-> (HsExpr GhcTc, Kind) -> TcM (HsExpr GhcTc, Kind)
forall a b. (a -> b) -> a -> b
$
    if Bool
add_void_arg
    then ( HsExpr GhcTc
builder_expr   -- still just return builder_expr; the void# arg is added
                          -- by dsConLike in the desugarer
         , Kind -> Kind
tcFunResultTy Kind
builder_ty )
    else (HsExpr GhcTc
builder_expr, Kind
builder_ty)

  | Bool
otherwise  -- Unidirectional
  = Name -> TcM (HsExpr GhcTc, Kind)
forall name a. Outputable name => name -> TcM a
nonBidirectionalErr Name
name
  where
    name :: Name
name    = PatSyn -> Name
patSynName PatSyn
ps
    builder :: Maybe (Id, Bool)
builder = PatSyn -> Maybe (Id, Bool)
patSynBuilder PatSyn
ps

add_void :: Bool -> Type -> Type
add_void :: Bool -> Kind -> Kind
add_void Bool
need_dummy_arg Kind
ty
  | Bool
need_dummy_arg = Kind -> Kind -> Kind
mkVisFunTyMany Kind
voidPrimTy Kind
ty
  | Bool
otherwise      = Kind
ty

tcPatToExpr :: Name -> [Located Name] -> LPat GhcRn
            -> Either MsgDoc (LHsExpr GhcRn)
-- Given a /pattern/, return an /expression/ that builds a value
-- that matches the pattern.  E.g. if the pattern is (Just [x]),
-- the expression is (Just [x]).  They look the same, but the
-- input uses constructors from HsPat and the output uses constructors
-- from HsExpr.
--
-- Returns (Left r) if the pattern is not invertible, for reason r.
-- See Note [Builder for a bidirectional pattern synonym]
tcPatToExpr :: Name
-> [Located Name] -> LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
tcPatToExpr Name
name [Located Name]
args LPat GhcRn
pat = LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go LPat GhcRn
pat
  where
    lhsVars :: NameSet
lhsVars = [Name] -> NameSet
mkNameSet ((Located Name -> Name) -> [Located Name] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map Located Name -> Name
forall l e. GenLocated l e -> e
unLoc [Located Name]
args)

    -- Make a prefix con for prefix and infix patterns for simplicity
    mkPrefixConExpr :: Located Name -> [LPat GhcRn]
                    -> Either MsgDoc (HsExpr GhcRn)
    mkPrefixConExpr :: Located Name -> [LPat GhcRn] -> Either MsgDoc (HsExpr GhcRn)
mkPrefixConExpr lcon :: Located Name
lcon@(L SrcSpan
loc Name
_) [LPat GhcRn]
pats
      = do { [LHsExpr GhcRn]
exprs <- (Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn))
-> [Located (Pat GhcRn)] -> Either MsgDoc [LHsExpr GhcRn]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn)
LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go [Located (Pat GhcRn)]
[LPat GhcRn]
pats
           ; HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return ((HsExpr GhcRn -> LHsExpr GhcRn -> HsExpr GhcRn)
-> HsExpr GhcRn -> [LHsExpr GhcRn] -> HsExpr GhcRn
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (\HsExpr GhcRn
x LHsExpr GhcRn
y -> XApp GhcRn -> LHsExpr GhcRn -> LHsExpr GhcRn -> HsExpr GhcRn
forall p. XApp p -> LHsExpr p -> LHsExpr p -> HsExpr p
HsApp NoExtField
XApp GhcRn
noExtField (SrcSpan -> HsExpr GhcRn -> LHsExpr GhcRn
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc HsExpr GhcRn
x) LHsExpr GhcRn
y)
                            (XVar GhcRn -> GenLocated SrcSpan (IdP GhcRn) -> HsExpr GhcRn
forall p. XVar p -> Located (IdP p) -> HsExpr p
HsVar NoExtField
XVar GhcRn
noExtField Located Name
GenLocated SrcSpan (IdP GhcRn)
lcon) [LHsExpr GhcRn]
exprs) }

    mkRecordConExpr :: Located Name -> HsRecFields GhcRn (LPat GhcRn)
                    -> Either MsgDoc (HsExpr GhcRn)
    mkRecordConExpr :: Located Name
-> HsRecFields GhcRn (LPat GhcRn) -> Either MsgDoc (HsExpr GhcRn)
mkRecordConExpr Located Name
con HsRecFields GhcRn (LPat GhcRn)
fields
      = do { HsRecFields GhcRn (LHsExpr GhcRn)
exprFields <- (Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn))
-> HsRecFields GhcRn (Located (Pat GhcRn))
-> Either MsgDoc (HsRecFields GhcRn (LHsExpr GhcRn))
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn)
LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go HsRecFields GhcRn (Located (Pat GhcRn))
HsRecFields GhcRn (LPat GhcRn)
fields
           ; HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (XRecordCon GhcRn
-> GenLocated SrcSpan (IdP GhcRn)
-> HsRecFields GhcRn (LHsExpr GhcRn)
-> HsExpr GhcRn
forall p.
XRecordCon p -> Located (IdP p) -> HsRecordBinds p -> HsExpr p
RecordCon NoExtField
XRecordCon GhcRn
noExtField Located Name
GenLocated SrcSpan (IdP GhcRn)
con HsRecFields GhcRn (LHsExpr GhcRn)
exprFields) }

    go :: LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
    go :: LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go (L SrcSpan
loc Pat GhcRn
p) = SrcSpan -> HsExpr GhcRn -> LHsExpr GhcRn
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc (HsExpr GhcRn -> LHsExpr GhcRn)
-> Either MsgDoc (HsExpr GhcRn) -> Either MsgDoc (LHsExpr GhcRn)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
go1 Pat GhcRn
p

    go1 :: Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
    go1 :: Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
go1 (ConPat NoExtField
XConPat GhcRn
NoExtField Located (ConLikeP GhcRn)
con HsConPatDetails GhcRn
info)
      = case HsConPatDetails GhcRn
info of
          PrefixCon [LPat GhcRn]
ps  -> Located Name -> [LPat GhcRn] -> Either MsgDoc (HsExpr GhcRn)
mkPrefixConExpr Located Name
Located (ConLikeP GhcRn)
con [LPat GhcRn]
ps
          InfixCon LPat GhcRn
l LPat GhcRn
r  -> Located Name -> [LPat GhcRn] -> Either MsgDoc (HsExpr GhcRn)
mkPrefixConExpr Located Name
Located (ConLikeP GhcRn)
con [LPat GhcRn
l,LPat GhcRn
r]
          RecCon HsRecFields GhcRn (LPat GhcRn)
fields -> Located Name
-> HsRecFields GhcRn (LPat GhcRn) -> Either MsgDoc (HsExpr GhcRn)
mkRecordConExpr Located Name
Located (ConLikeP GhcRn)
con HsRecFields GhcRn (LPat GhcRn)
fields

    go1 (SigPat XSigPat GhcRn
_ LPat GhcRn
pat HsPatSigType (NoGhcTc GhcRn)
_) = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
go1 (Located (Pat GhcRn) -> Pat GhcRn
forall l e. GenLocated l e -> e
unLoc Located (Pat GhcRn)
LPat GhcRn
pat)
        -- See Note [Type signatures and the builder expression]

    go1 (VarPat XVarPat GhcRn
_ (L SrcSpan
l IdP GhcRn
var))
        | Name
IdP GhcRn
var Name -> NameSet -> Bool
`elemNameSet` NameSet
lhsVars
        = HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn))
-> HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ XVar GhcRn -> GenLocated SrcSpan (IdP GhcRn) -> HsExpr GhcRn
forall p. XVar p -> Located (IdP p) -> HsExpr p
HsVar NoExtField
XVar GhcRn
noExtField (SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
l Name
IdP GhcRn
var)
        | Bool
otherwise
        = MsgDoc -> Either MsgDoc (HsExpr GhcRn)
forall a b. a -> Either a b
Left (MsgDoc -> MsgDoc
quotes (Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
IdP GhcRn
var) MsgDoc -> MsgDoc -> MsgDoc
<+> String -> MsgDoc
text String
"is not bound by the LHS of the pattern synonym")
    go1 (ParPat XParPat GhcRn
_ LPat GhcRn
pat)          = (LHsExpr GhcRn -> HsExpr GhcRn)
-> Either MsgDoc (LHsExpr GhcRn) -> Either MsgDoc (HsExpr GhcRn)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (XPar GhcRn -> LHsExpr GhcRn -> HsExpr GhcRn
forall p. XPar p -> LHsExpr p -> HsExpr p
HsPar NoExtField
XPar GhcRn
noExtField) (Either MsgDoc (LHsExpr GhcRn) -> Either MsgDoc (HsExpr GhcRn))
-> Either MsgDoc (LHsExpr GhcRn) -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go LPat GhcRn
pat
    go1 p :: Pat GhcRn
p@(ListPat XListPat GhcRn
reb [LPat GhcRn]
pats)
      | Maybe SyntaxExprRn
XListPat GhcRn
Nothing <- XListPat GhcRn
reb = do { [LHsExpr GhcRn]
exprs <- (Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn))
-> [Located (Pat GhcRn)] -> Either MsgDoc [LHsExpr GhcRn]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn)
LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go [Located (Pat GhcRn)]
[LPat GhcRn]
pats
                            ; HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn))
-> HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ XExplicitList GhcRn
-> Maybe (SyntaxExpr GhcRn) -> [LHsExpr GhcRn] -> HsExpr GhcRn
forall p.
XExplicitList p -> Maybe (SyntaxExpr p) -> [LHsExpr p] -> HsExpr p
ExplicitList NoExtField
XExplicitList GhcRn
noExtField Maybe (SyntaxExpr GhcRn)
forall a. Maybe a
Nothing [LHsExpr GhcRn]
exprs }
      | Bool
otherwise                   = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertibleListPat Pat GhcRn
p
    go1 (TuplePat XTuplePat GhcRn
_ [LPat GhcRn]
pats Boxity
box)       = do { [LHsExpr GhcRn]
exprs <- (Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn))
-> [Located (Pat GhcRn)] -> Either MsgDoc [LHsExpr GhcRn]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located (Pat GhcRn) -> Either MsgDoc (LHsExpr GhcRn)
LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go [Located (Pat GhcRn)]
[LPat GhcRn]
pats
                                         ; HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn))
-> HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ XExplicitTuple GhcRn -> [LHsTupArg GhcRn] -> Boxity -> HsExpr GhcRn
forall p. XExplicitTuple p -> [LHsTupArg p] -> Boxity -> HsExpr p
ExplicitTuple NoExtField
XExplicitTuple GhcRn
noExtField
                                           ((LHsExpr GhcRn -> LHsTupArg GhcRn)
-> [LHsExpr GhcRn] -> [LHsTupArg GhcRn]
forall a b. (a -> b) -> [a] -> [b]
map (HsTupArg GhcRn -> LHsTupArg GhcRn
forall e. e -> Located e
noLoc (HsTupArg GhcRn -> LHsTupArg GhcRn)
-> (LHsExpr GhcRn -> HsTupArg GhcRn)
-> LHsExpr GhcRn
-> LHsTupArg GhcRn
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (XPresent GhcRn -> LHsExpr GhcRn -> HsTupArg GhcRn
forall id. XPresent id -> LHsExpr id -> HsTupArg id
Present NoExtField
XPresent GhcRn
noExtField)) [LHsExpr GhcRn]
exprs)
                                                                           Boxity
box }
    go1 (SumPat XSumPat GhcRn
_ LPat GhcRn
pat Int
alt Int
arity)    = do { HsExpr GhcRn
expr <- Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
go1 (Located (Pat GhcRn) -> Pat GhcRn
forall l e. GenLocated l e -> e
unLoc Located (Pat GhcRn)
LPat GhcRn
pat)
                                         ; HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn))
-> HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ XExplicitSum GhcRn -> Int -> Int -> LHsExpr GhcRn -> HsExpr GhcRn
forall p. XExplicitSum p -> Int -> Int -> LHsExpr p -> HsExpr p
ExplicitSum NoExtField
XExplicitSum GhcRn
noExtField Int
alt Int
arity
                                                                   (HsExpr GhcRn -> LHsExpr GhcRn
forall e. e -> Located e
noLoc HsExpr GhcRn
expr)
                                         }
    go1 (LitPat XLitPat GhcRn
_ HsLit GhcRn
lit)              = HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn))
-> HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ XLitE GhcRn -> HsLit GhcRn -> HsExpr GhcRn
forall p. XLitE p -> HsLit p -> HsExpr p
HsLit NoExtField
XLitE GhcRn
noExtField HsLit GhcRn
lit
    go1 (NPat XNPat GhcRn
_ (L SrcSpan
_ HsOverLit GhcRn
n) Maybe (SyntaxExpr GhcRn)
mb_neg SyntaxExpr GhcRn
_)
        | Just (SyntaxExprRn HsExpr GhcRn
neg) <- Maybe (SyntaxExpr GhcRn)
mb_neg
                                    = HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn))
-> HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ LHsExpr GhcRn -> HsExpr GhcRn
forall l e. GenLocated l e -> e
unLoc (LHsExpr GhcRn -> HsExpr GhcRn) -> LHsExpr GhcRn -> HsExpr GhcRn
forall a b. (a -> b) -> a -> b
$ (LHsExpr GhcRn -> LHsExpr GhcRn -> LHsExpr GhcRn)
-> LHsExpr GhcRn -> [LHsExpr GhcRn] -> LHsExpr GhcRn
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' LHsExpr GhcRn -> LHsExpr GhcRn -> LHsExpr GhcRn
forall (id :: Pass).
IsPass id =>
LHsExpr (GhcPass id)
-> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)
nlHsApp (HsExpr GhcRn -> LHsExpr GhcRn
forall e. e -> Located e
noLoc HsExpr GhcRn
neg)
                                                       [HsExpr GhcRn -> LHsExpr GhcRn
forall e. e -> Located e
noLoc (XOverLitE GhcRn -> HsOverLit GhcRn -> HsExpr GhcRn
forall p. XOverLitE p -> HsOverLit p -> HsExpr p
HsOverLit NoExtField
XOverLitE GhcRn
noExtField HsOverLit GhcRn
n)]
        | Bool
otherwise                 = HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall (m :: * -> *) a. Monad m => a -> m a
return (HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn))
-> HsExpr GhcRn -> Either MsgDoc (HsExpr GhcRn)
forall a b. (a -> b) -> a -> b
$ XOverLitE GhcRn -> HsOverLit GhcRn -> HsExpr GhcRn
forall p. XOverLitE p -> HsOverLit p -> HsExpr p
HsOverLit NoExtField
XOverLitE GhcRn
noExtField HsOverLit GhcRn
n
    go1 (SplicePat XSplicePat GhcRn
_ (HsSpliced XSpliced GhcRn
_ ThModFinalizers
_ (HsSplicedPat Pat GhcRn
pat)))
                                    = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
go1 Pat GhcRn
pat
    go1 (SplicePat XSplicePat GhcRn
_ (HsSpliced{})) = String -> Either MsgDoc (HsExpr GhcRn)
forall a. String -> a
panic String
"Invalid splice variety"

    -- The following patterns are not invertible.
    go1 p :: Pat GhcRn
p@(BangPat {})                       = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p -- #14112
    go1 p :: Pat GhcRn
p@(LazyPat {})                       = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p
    go1 p :: Pat GhcRn
p@(WildPat {})                       = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p
    go1 p :: Pat GhcRn
p@(AsPat {})                         = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p
    go1 p :: Pat GhcRn
p@(ViewPat {})                       = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p
    go1 p :: Pat GhcRn
p@(NPlusKPat {})                     = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p
    go1 p :: Pat GhcRn
p@(SplicePat XSplicePat GhcRn
_ (HsTypedSplice {}))   = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p
    go1 p :: Pat GhcRn
p@(SplicePat XSplicePat GhcRn
_ (HsUntypedSplice {})) = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p
    go1 p :: Pat GhcRn
p@(SplicePat XSplicePat GhcRn
_ (HsQuasiQuote {}))    = Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p

    notInvertible :: Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertible Pat GhcRn
p = MsgDoc -> Either MsgDoc (HsExpr GhcRn)
forall a b. a -> Either a b
Left (Pat GhcRn -> MsgDoc
not_invertible_msg Pat GhcRn
p)

    not_invertible_msg :: Pat GhcRn -> MsgDoc
not_invertible_msg Pat GhcRn
p
      =   String -> MsgDoc
text String
"Pattern" MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc -> MsgDoc
quotes (Pat GhcRn -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Pat GhcRn
p) MsgDoc -> MsgDoc -> MsgDoc
<+> String -> MsgDoc
text String
"is not invertible"
      MsgDoc -> MsgDoc -> MsgDoc
$+$ MsgDoc -> Int -> MsgDoc -> MsgDoc
hang (String -> MsgDoc
text String
"Suggestion: instead use an explicitly bidirectional"
                MsgDoc -> MsgDoc -> MsgDoc
<+> String -> MsgDoc
text String
"pattern synonym, e.g.")
             Int
2 (MsgDoc -> Int -> MsgDoc -> MsgDoc
hang (String -> MsgDoc
text String
"pattern" MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
pp_name MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
pp_args MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
larrow
                      MsgDoc -> MsgDoc -> MsgDoc
<+> Located (Pat GhcRn) -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Located (Pat GhcRn)
LPat GhcRn
pat MsgDoc -> MsgDoc -> MsgDoc
<+> String -> MsgDoc
text String
"where")
                   Int
2 (MsgDoc
pp_name MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
pp_args MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc
equals MsgDoc -> MsgDoc -> MsgDoc
<+> String -> MsgDoc
text String
"..."))
      where
        pp_name :: MsgDoc
pp_name = Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Name
name
        pp_args :: MsgDoc
pp_args = [MsgDoc] -> MsgDoc
hsep ((Located Name -> MsgDoc) -> [Located Name] -> [MsgDoc]
forall a b. (a -> b) -> [a] -> [b]
map Located Name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr [Located Name]
args)

    -- We should really be able to invert list patterns, even when
    -- rebindable syntax is on, but doing so involves a bit of
    -- refactoring; see #14380.  Until then we reject with a
    -- helpful error message.
    notInvertibleListPat :: Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
notInvertibleListPat Pat GhcRn
p
      = MsgDoc -> Either MsgDoc (HsExpr GhcRn)
forall a b. a -> Either a b
Left ([MsgDoc] -> MsgDoc
vcat [ Pat GhcRn -> MsgDoc
not_invertible_msg Pat GhcRn
p
                   , String -> MsgDoc
text String
"Reason: rebindable syntax is on."
                   , String -> MsgDoc
text String
"This is fixable: add use-case to #14380" ])

{- Note [Builder for a bidirectional pattern synonym]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For a bidirectional pattern synonym we need to produce an /expression/
that matches the supplied /pattern/, given values for the arguments
of the pattern synonym.  For example
  pattern F x y = (Just x, [y])
The 'builder' for F looks like
  $builderF x y = (Just x, [y])

We can't always do this:
 * Some patterns aren't invertible; e.g. view patterns
      pattern F x = (reverse -> x:_)

 * The RHS pattern might bind more variables than the pattern
   synonym, so again we can't invert it
      pattern F x = (x,y)

 * Ditto wildcards
      pattern F x = (x,_)


Note [Redundant constraints for builder]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The builder can have redundant constraints, which are awkward to eliminate.
Consider
   pattern P = Just 34
To match against this pattern we need (Eq a, Num a).  But to build
(Just 34) we need only (Num a).  Fortunately instTcSigFromId sets
sig_warn_redundant to False.

************************************************************************
*                                                                      *
         Helper functions
*                                                                      *
************************************************************************

Note [As-patterns in pattern synonym definitions]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The rationale for rejecting as-patterns in pattern synonym definitions
is that an as-pattern would introduce nonindependent pattern synonym
arguments, e.g. given a pattern synonym like:

        pattern K x y = x@(Just y)

one could write a nonsensical function like

        f (K Nothing x) = ...

or
        g (K (Just True) False) = ...

Note [Type signatures and the builder expression]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
   pattern L x = Left x :: Either [a] [b]

In tc{Infer/Check}PatSynDecl we will check that the pattern has the
specified type.  We check the pattern *as a pattern*, so the type
signature is a pattern signature, and so brings 'a' and 'b' into
scope.  But we don't have a way to bind 'a, b' in the LHS, as we do
'x', say.  Nevertheless, the signature may be useful to constrain
the type.

When making the binding for the *builder*, though, we don't want
  $buildL x = Left x :: Either [a] [b]
because that wil either mean (forall a b. Either [a] [b]), or we'll
get a complaint that 'a' and 'b' are out of scope. (Actually the
latter; #9867.)  No, the job of the signature is done, so when
converting the pattern to an expression (for the builder RHS) we
simply discard the signature.

Note [Record PatSyn Desugaring]
-------------------------------
It is important that prov_theta comes before req_theta as this ordering is used
when desugaring record pattern synonym updates.

Any change to this ordering should make sure to change GHC.HsToCore.Expr if you
want to avoid difficult to decipher core lint errors!
 -}


nonBidirectionalErr :: Outputable name => name -> TcM a
nonBidirectionalErr :: forall name a. Outputable name => name -> TcM a
nonBidirectionalErr name
name = MsgDoc -> TcM a
forall a. MsgDoc -> TcM a
failWithTc (MsgDoc -> TcM a) -> MsgDoc -> TcM a
forall a b. (a -> b) -> a -> b
$
    String -> MsgDoc
text String
"non-bidirectional pattern synonym"
    MsgDoc -> MsgDoc -> MsgDoc
<+> MsgDoc -> MsgDoc
quotes (name -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr name
name) MsgDoc -> MsgDoc -> MsgDoc
<+> String -> MsgDoc
text String
"used in an expression"

-- Walk the whole pattern and for all ConPatOuts, collect the
-- existentially-bound type variables and evidence binding variables.
--
-- These are used in computing the type of a pattern synonym and also
-- in generating matcher functions, since success continuations need
-- to be passed these pattern-bound evidences.
tcCollectEx
  :: LPat GhcTc
  -> ( [TyVar]        -- Existentially-bound type variables
                      -- in correctly-scoped order; e.g. [ k:*, x:k ]
     , [EvVar] )      -- and evidence variables

tcCollectEx :: LPat GhcTc -> ([Id], [Id])
tcCollectEx LPat GhcTc
pat = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
pat
  where
    go :: LPat GhcTc -> ([TyVar], [EvVar])
    go :: LPat GhcTc -> ([Id], [Id])
go = Pat GhcTc -> ([Id], [Id])
go1 (Pat GhcTc -> ([Id], [Id]))
-> (Located (Pat GhcTc) -> Pat GhcTc)
-> Located (Pat GhcTc)
-> ([Id], [Id])
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Located (Pat GhcTc) -> Pat GhcTc
forall l e. GenLocated l e -> e
unLoc

    go1 :: Pat GhcTc -> ([TyVar], [EvVar])
    go1 :: Pat GhcTc -> ([Id], [Id])
go1 (LazyPat XLazyPat GhcTc
_ LPat GhcTc
p)      = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p
    go1 (AsPat XAsPat GhcTc
_ Located (IdP GhcTc)
_ LPat GhcTc
p)      = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p
    go1 (ParPat XParPat GhcTc
_ LPat GhcTc
p)       = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p
    go1 (BangPat XBangPat GhcTc
_ LPat GhcTc
p)      = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p
    go1 (ListPat XListPat GhcTc
_ [LPat GhcTc]
ps)     = [([Id], [Id])] -> ([Id], [Id])
forall {a} {a}. [([a], [a])] -> ([a], [a])
mergeMany ([([Id], [Id])] -> ([Id], [Id]))
-> ([Located (Pat GhcTc)] -> [([Id], [Id])])
-> [Located (Pat GhcTc)]
-> ([Id], [Id])
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Located (Pat GhcTc) -> ([Id], [Id]))
-> [Located (Pat GhcTc)] -> [([Id], [Id])]
forall a b. (a -> b) -> [a] -> [b]
map Located (Pat GhcTc) -> ([Id], [Id])
LPat GhcTc -> ([Id], [Id])
go ([Located (Pat GhcTc)] -> ([Id], [Id]))
-> [Located (Pat GhcTc)] -> ([Id], [Id])
forall a b. (a -> b) -> a -> b
$ [Located (Pat GhcTc)]
[LPat GhcTc]
ps
    go1 (TuplePat XTuplePat GhcTc
_ [LPat GhcTc]
ps Boxity
_)  = [([Id], [Id])] -> ([Id], [Id])
forall {a} {a}. [([a], [a])] -> ([a], [a])
mergeMany ([([Id], [Id])] -> ([Id], [Id]))
-> ([Located (Pat GhcTc)] -> [([Id], [Id])])
-> [Located (Pat GhcTc)]
-> ([Id], [Id])
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Located (Pat GhcTc) -> ([Id], [Id]))
-> [Located (Pat GhcTc)] -> [([Id], [Id])]
forall a b. (a -> b) -> [a] -> [b]
map Located (Pat GhcTc) -> ([Id], [Id])
LPat GhcTc -> ([Id], [Id])
go ([Located (Pat GhcTc)] -> ([Id], [Id]))
-> [Located (Pat GhcTc)] -> ([Id], [Id])
forall a b. (a -> b) -> a -> b
$ [Located (Pat GhcTc)]
[LPat GhcTc]
ps
    go1 (SumPat XSumPat GhcTc
_ LPat GhcTc
p Int
_ Int
_)   = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p
    go1 (ViewPat XViewPat GhcTc
_ LHsExpr GhcTc
_ LPat GhcTc
p)    = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p
    go1 con :: Pat GhcTc
con@ConPat{ pat_con_ext :: forall p. Pat p -> XConPat p
pat_con_ext = XConPat GhcTc
con' }
                           = ([Id], [Id]) -> ([Id], [Id]) -> ([Id], [Id])
forall {a} {a}. ([a], [a]) -> ([a], [a]) -> ([a], [a])
merge (ConPatTc -> [Id]
cpt_tvs XConPat GhcTc
ConPatTc
con', ConPatTc -> [Id]
cpt_dicts XConPat GhcTc
ConPatTc
con') (([Id], [Id]) -> ([Id], [Id])) -> ([Id], [Id]) -> ([Id], [Id])
forall a b. (a -> b) -> a -> b
$
                              HsConPatDetails GhcTc -> ([Id], [Id])
goConDetails (HsConPatDetails GhcTc -> ([Id], [Id]))
-> HsConPatDetails GhcTc -> ([Id], [Id])
forall a b. (a -> b) -> a -> b
$ Pat GhcTc -> HsConPatDetails GhcTc
forall p. Pat p -> HsConPatDetails p
pat_args Pat GhcTc
con
    go1 (SigPat XSigPat GhcTc
_ LPat GhcTc
p HsPatSigType (NoGhcTc GhcTc)
_)     = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p
    go1 (XPat (CoPat HsWrapper
_ Pat GhcTc
p Kind
_)) = Pat GhcTc -> ([Id], [Id])
go1 Pat GhcTc
p
    go1 (NPlusKPat XNPlusKPat GhcTc
_ Located (IdP GhcTc)
n Located (HsOverLit GhcTc)
k HsOverLit GhcTc
_ SyntaxExpr GhcTc
geq SyntaxExpr GhcTc
subtract)
      = String -> MsgDoc -> ([Id], [Id])
forall a. HasCallStack => String -> MsgDoc -> a
pprPanic String
"TODO: NPlusKPat" (MsgDoc -> ([Id], [Id])) -> MsgDoc -> ([Id], [Id])
forall a b. (a -> b) -> a -> b
$ Located Id -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Located Id
Located (IdP GhcTc)
n MsgDoc -> MsgDoc -> MsgDoc
$$ Located (HsOverLit GhcTc) -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr Located (HsOverLit GhcTc)
k MsgDoc -> MsgDoc -> MsgDoc
$$ SyntaxExprTc -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr SyntaxExpr GhcTc
SyntaxExprTc
geq MsgDoc -> MsgDoc -> MsgDoc
$$ SyntaxExprTc -> MsgDoc
forall a. Outputable a => a -> MsgDoc
ppr SyntaxExpr GhcTc
SyntaxExprTc
subtract
    go1 Pat GhcTc
_                   = ([Id], [Id])
forall {a} {a}. ([a], [a])
empty

    goConDetails :: HsConPatDetails GhcTc -> ([TyVar], [EvVar])
    goConDetails :: HsConPatDetails GhcTc -> ([Id], [Id])
goConDetails (PrefixCon [LPat GhcTc]
ps) = [([Id], [Id])] -> ([Id], [Id])
forall {a} {a}. [([a], [a])] -> ([a], [a])
mergeMany ([([Id], [Id])] -> ([Id], [Id]))
-> ([Located (Pat GhcTc)] -> [([Id], [Id])])
-> [Located (Pat GhcTc)]
-> ([Id], [Id])
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Located (Pat GhcTc) -> ([Id], [Id]))
-> [Located (Pat GhcTc)] -> [([Id], [Id])]
forall a b. (a -> b) -> [a] -> [b]
map Located (Pat GhcTc) -> ([Id], [Id])
LPat GhcTc -> ([Id], [Id])
go ([Located (Pat GhcTc)] -> ([Id], [Id]))
-> [Located (Pat GhcTc)] -> ([Id], [Id])
forall a b. (a -> b) -> a -> b
$ [Located (Pat GhcTc)]
[LPat GhcTc]
ps
    goConDetails (InfixCon LPat GhcTc
p1 LPat GhcTc
p2) = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p1 ([Id], [Id]) -> ([Id], [Id]) -> ([Id], [Id])
forall {a} {a}. ([a], [a]) -> ([a], [a]) -> ([a], [a])
`merge` LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p2
    goConDetails (RecCon HsRecFields{ rec_flds :: forall p arg. HsRecFields p arg -> [LHsRecField p arg]
rec_flds = [LHsRecField GhcTc (LPat GhcTc)]
flds })
      = [([Id], [Id])] -> ([Id], [Id])
forall {a} {a}. [([a], [a])] -> ([a], [a])
mergeMany ([([Id], [Id])] -> ([Id], [Id]))
-> ([LHsRecField GhcTc (Located (Pat GhcTc))] -> [([Id], [Id])])
-> [LHsRecField GhcTc (Located (Pat GhcTc))]
-> ([Id], [Id])
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (LHsRecField GhcTc (Located (Pat GhcTc)) -> ([Id], [Id]))
-> [LHsRecField GhcTc (Located (Pat GhcTc))] -> [([Id], [Id])]
forall a b. (a -> b) -> [a] -> [b]
map LHsRecField GhcTc (Located (Pat GhcTc)) -> ([Id], [Id])
LHsRecField GhcTc (LPat GhcTc) -> ([Id], [Id])
goRecFd ([LHsRecField GhcTc (Located (Pat GhcTc))] -> ([Id], [Id]))
-> [LHsRecField GhcTc (Located (Pat GhcTc))] -> ([Id], [Id])
forall a b. (a -> b) -> a -> b
$ [LHsRecField GhcTc (Located (Pat GhcTc))]
[LHsRecField GhcTc (LPat GhcTc)]
flds

    goRecFd :: LHsRecField GhcTc (LPat GhcTc) -> ([TyVar], [EvVar])
    goRecFd :: LHsRecField GhcTc (LPat GhcTc) -> ([Id], [Id])
goRecFd (L SrcSpan
_ HsRecField{ hsRecFieldArg :: forall id arg. HsRecField' id arg -> arg
hsRecFieldArg = LPat GhcTc
p }) = LPat GhcTc -> ([Id], [Id])
go LPat GhcTc
p

    merge :: ([a], [a]) -> ([a], [a]) -> ([a], [a])
merge ([a]
vs1, [a]
evs1) ([a]
vs2, [a]
evs2) = ([a]
vs1 [a] -> [a] -> [a]
forall a. [a] -> [a] -> [a]
++ [a]
vs2, [a]
evs1 [a] -> [a] -> [a]
forall a. [a] -> [a] -> [a]
++ [a]
evs2)
    mergeMany :: [([a], [a])] -> ([a], [a])
mergeMany = (([a], [a]) -> ([a], [a]) -> ([a], [a]))
-> ([a], [a]) -> [([a], [a])] -> ([a], [a])
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr ([a], [a]) -> ([a], [a]) -> ([a], [a])
forall {a} {a}. ([a], [a]) -> ([a], [a]) -> ([a], [a])
merge ([a], [a])
forall {a} {a}. ([a], [a])
empty
    empty :: ([a], [a])
empty     = ([], [])