Distribution.Simple.ShowBuildInfo

This module defines a simple JSON-based format for exporting basic information about a Cabal package and the compiler configuration Cabal would use to build it. This can be produced with the cabal build --enable-build-info command.

This format is intended for consumption by external tooling and should therefore be rather stable. Moreover, this allows tooling users to avoid linking against Cabal. This is an important advantage as direct API usage tends to be rather fragile in the presence of user-initiated upgrades of Cabal.

Below is an example of the output this module produces,

{ "cabal-lib-version": "1.23.0.0",
  "compiler": {
    "flavour": GHC,
    "compiler-id": "ghc-7.10.2",
    "path": "usrbin/ghc",
  },
  "components": [
    { "type": "lib",
      "name": "lib:Cabal",
      "compiler-args":
        ["-O", "-XHaskell98", "-Wall",
         "-package-id", "parallel-3.2.0.6-b79c38c5c25fff77f3ea7271851879eb"]
      "modules": [Project.ModA, Project.ModB, Paths_project],
      "src-files": [],
      "src-dirs": ["src"]
    }
  ]
}

The output format needs to be validated against 'docjson-schemasbuild-info.schema.json'. If the format changes, update the schema as well!

The cabal-lib-version property provides the version of the Cabal library which generated the output. The compiler property gives some basic information about the compiler Cabal would use to compile the package.

The components property gives a list of the Cabal Components defined by the package. Each has,

• type: the type of the component (one of lib, exe, test, bench, or flib)
• name: a string serving to uniquely identify the component within the package.
• compiler-args: the command-line arguments Cabal would pass to the compiler to compile the component
• modules: the modules belonging to the component
• src-dirs: a list of directories where the modules might be found
• src-files: any other Haskell sources needed by the component

Note: At the moment this is only supported when using the GHC compiler.

Documentation

mkBuildInfo

Arguments

:: FilePath

The source directory of the package

-> PackageDescription

Mostly information from the .cabal file

-> LocalBuildInfo

Configuration information

-> BuildFlags

Flags that the user passed to build

-> (ConfiguredProgram, Compiler)

Compiler information. Needs to be passed explicitly, as we can't extract that information here without some partial function.

-> [TargetInfo]

-> ([String], Json)

Json representation of buildinfo alongside generated warnings

Construct a JSON document describing the build information for a package.

mkBuildInfo'

Arguments

:: Json

The Json from mkCompilerInfo

-> [Json]

The Json from mkComponentInfo

-> [(String, Json)]

A variant of mkBuildInfo if you need to call mkCompilerInfo and mkComponentInfo yourself.

If you change the format or any name in the output json, don't forget to update the schema at /doc/json-schemas/build-info.schema.json and the docs of --enable-build-info/--disable-build-info.

mkCompilerInfo :: ConfiguredProgram -> Compiler -> Json

mkComponentInfo :: FilePath -> PackageDescription -> LocalBuildInfo -> ComponentLocalBuildInfo -> ([String], Json)