path: root/hadrian/src/Rules/Generate.hs

module Rules.Generate (
    isGeneratedCmmFile, compilerDependencies, generatePackageCode,
    generateRules, copyRules, generatedDependencies, generatedGhcDependencies,
    ghcPrimDependencies
    ) where

import Base
import qualified Context
import Expression
import Flavour
import Hadrian.Oracles.TextFile (lookupValueOrError)
import Oracles.Flag
import Oracles.ModuleFiles
import Oracles.Setting
import Packages
import Rules.Gmp
import Rules.Libffi
import Settings
import Target
import Utilities

-- | Track this file to rebuild generated files whenever it changes.
trackGenerateHs :: Expr ()
trackGenerateHs = expr $ need [sourcePath -/- "Rules/Generate.hs"]

primopsSource :: FilePath
primopsSource = "compiler/prelude/primops.txt.pp"

primopsTxt :: Stage -> FilePath
primopsTxt stage = buildDir (vanillaContext stage compiler) -/- "primops.txt"

isGeneratedCmmFile :: FilePath -> Bool
isGeneratedCmmFile file = takeBaseName file == "AutoApply"

ghcPrimDependencies :: Expr [FilePath]
ghcPrimDependencies = do
    stage <- getStage
    path  <- expr $ buildPath (vanillaContext stage ghcPrim)
    return [path -/- "GHC/Prim.hs", path -/- "GHC/PrimopWrappers.hs"]

derivedConstantsDependencies :: [FilePath]
derivedConstantsDependencies = fmap (generatedDir -/-)
    [ "DerivedConstants.h"
    , "GHCConstantsHaskellExports.hs"
    , "GHCConstantsHaskellType.hs"
    , "GHCConstantsHaskellWrappers.hs" ]

compilerDependencies :: Expr [FilePath]
compilerDependencies = do
    root    <- getBuildRoot
    stage   <- getStage
    isGmp   <- (== integerGmp) <$> getIntegerPackage
    ghcPath <- expr $ buildPath (vanillaContext stage compiler)
    gmpPath <- expr gmpBuildPath
    rtsPath <- expr (rtsBuildPath stage)
    mconcat [ return ((root -/-) <$> derivedConstantsDependencies)
            , notStage0 ? isGmp ? return [gmpPath -/- gmpLibraryH]
            , notStage0 ? return ((rtsPath -/-) <$> libffiHeaderFiles)
            , return $ fmap (ghcPath -/-)
                  [ "primop-can-fail.hs-incl"
                  , "primop-code-size.hs-incl"
                  , "primop-commutable.hs-incl"
                  , "primop-data-decl.hs-incl"
                  , "primop-fixity.hs-incl"
                  , "primop-has-side-effects.hs-incl"
                  , "primop-list.hs-incl"
                  , "primop-out-of-line.hs-incl"
                  , "primop-primop-info.hs-incl"
                  , "primop-strictness.hs-incl"
                  , "primop-tag.hs-incl"
                  , "primop-vector-tycons.hs-incl"
                  , "primop-vector-tys-exports.hs-incl"
                  , "primop-vector-tys.hs-incl"
                  , "primop-vector-uniques.hs-incl" ] ]

generatedDependencies :: Expr [FilePath]
generatedDependencies = do
    root     <- getBuildRoot
    stage    <- getStage
    rtsPath  <- expr (rtsBuildPath stage)
    includes <- expr includesDependencies
    mconcat [ package compiler ? compilerDependencies
            , package ghcPrim  ? ghcPrimDependencies
            , package rts      ? return (fmap (rtsPath -/-) libffiHeaderFiles
                ++ includes
                ++ fmap (root -/-) derivedConstantsDependencies)
            , stage0 ? return includes ]

generate :: FilePath -> Context -> Expr String -> Action ()
generate file context expr = do
    contents <- interpretInContext context expr
    writeFileChanged file contents
    putSuccess $ "| Successfully generated " ++ file ++ "."

generatePackageCode :: Context -> Rules ()
generatePackageCode context@(Context stage pkg _) = do
    root <- buildRootRules
    let dir         = buildDir context
        generated f = (root -/- dir ++ "//*.hs") ?== f && not ("//autogen/*" ?== f)
        go gen file = generate file context gen
    generated ?> \file -> do
        let unpack = fromMaybe . error $ "No generator for " ++ file ++ "."
        (src, builder) <- unpack <$> findGenerator context file
        need [src]
        build $ target context builder [src] [file]
        let boot = src -<.> "hs-boot"
        whenM (doesFileExist boot) $ do
            let target = file -<.> "hs-boot"
            copyFile boot target
            produces [target]

    priority 2.0 $ do
        when (pkg == compiler) $ do
            root <//> dir -/- "Config.hs" %> go generateConfigHs
            root <//> dir -/- "*.hs-incl" %> genPrimopCode context
        when (pkg == ghcPrim) $ do
            root <//> dir -/- "GHC/Prim.hs" %> genPrimopCode context
            root <//> dir -/- "GHC/PrimopWrappers.hs" %> genPrimopCode context
        when (pkg == ghcPkg) $
            root <//> dir -/- "Version.hs" %> go generateVersionHs

    when (pkg == compiler) $ do
        root -/- primopsTxt stage %> \file -> do
            includes <- includesDependencies
            need $ [primopsSource] ++ includes
            build $ target context HsCpp [primopsSource] [file]

        root -/- stageString stage <//> "ghc_boot_platform.h" %>
            go generateGhcBootPlatformH

    when (pkg == rts) $ do
        root <//> dir -/- "cmm/AutoApply.cmm" %> \file ->
            build $ target context GenApply [] [file]
        -- TODO: This should be fixed properly, e.g. generated here on demand.
        (root <//> dir -/- "DerivedConstants.h") <~ (buildRoot <&> (-/- generatedDir))
        (root <//> dir -/- "ghcautoconf.h") <~ (buildRoot <&> (-/- generatedDir))
        (root <//> dir -/- "ghcplatform.h") <~ (buildRoot <&> (-/- generatedDir))
        (root <//> dir -/- "ghcversion.h") <~ (buildRoot <&> (-/- generatedDir))
 where
    pattern <~ mdir = pattern %> \file -> do
        dir <- mdir
        copyFile (dir -/- takeFileName file) file

genPrimopCode :: Context -> FilePath -> Action ()
genPrimopCode context@(Context stage _pkg _) file = do
    root <- buildRoot
    need [root -/- primopsTxt stage]
    build $ target context GenPrimopCode [root -/- primopsTxt stage] [file]

copyRules :: Rules ()
copyRules = do
    root <- buildRootRules
    forM_ [Stage0 ..] $ \stage -> do
        let prefix = root -/- stageString stage -/- "lib"

            infixl 1 <~
            pattern <~ mdir = pattern %> \file -> do
                dir <- mdir
                copyFile (dir -/- makeRelative prefix file) file

        prefix -/- "ghc-usage.txt"     <~ return "driver"
        prefix -/- "ghci-usage.txt"    <~ return "driver"
        prefix -/- "llvm-targets"      <~ return "."
        prefix -/- "llvm-passes"       <~ return "."
        prefix -/- "platformConstants" <~ (buildRoot <&> (-/- generatedDir))
        prefix -/- "template-hsc.h"    <~ return (pkgPath hsc2hs)

        prefix -/- "html//*"           <~ return "utils/haddock/haddock-api/resources"
        prefix -/- "latex//*"          <~ return "utils/haddock/haddock-api/resources"

generateRules :: Rules ()
generateRules = do
    root <- buildRootRules

    (root -/- "ghc-stage1") <~ ghcWrapper Stage1
    (root -/- "ghc-stage2") <~ ghcWrapper Stage2

    priority 2.0 $ (root -/- generatedDir -/- "ghcautoconf.h") <~ generateGhcAutoconfH
    priority 2.0 $ (root -/- generatedDir -/- "ghcplatform.h") <~ generateGhcPlatformH
    priority 2.0 $ (root -/- generatedDir -/-  "ghcversion.h") <~ generateGhcVersionH
    forM_ [Stage0 ..] $ \stage -> do
        let prefix = root -/- stageString stage -/- "lib"
            go gen file = generate file (semiEmptyTarget stage) gen
        priority 2.0 $ (prefix -/- "settings") %> go generateSettings

    -- TODO: simplify, get rid of fake rts context
    root -/- generatedDir ++ "//*" %> \file -> do
        withTempDir $ \dir -> build $
            target (rtsContext Stage1) DeriveConstants [] [file, dir]
  where
    file <~ gen = file %> \out -> generate out emptyTarget gen

-- TODO: Use the Types, Luke! (drop partial function)
-- We sometimes need to evaluate expressions that do not require knowing all
-- information about the context. In this case, we don't want to know anything.
semiEmptyTarget :: Stage -> Context
semiEmptyTarget stage = vanillaContext stage
  (error "Rules.Generate.emptyTarget: unknown package")

emptyTarget :: Context
emptyTarget = vanillaContext (error "Rules.Generate.emptyTarget: unknown stage")
                             (error "Rules.Generate.emptyTarget: unknown package")

-- Generators

-- | GHC wrapper scripts used for passing the path to the right package database
-- when invoking in-tree GHC executables.
ghcWrapper :: Stage -> Expr String
ghcWrapper Stage0 = error "Stage0 GHC does not require a wrapper script to run."
ghcWrapper stage  = do
    dbPath  <- expr $ packageDbPath stage
    ghcPath <- expr $ programPath (vanillaContext (pred stage) ghc)
    return $ unwords $ map show $ [ ghcPath ]
                               ++ [ "-package-db " ++ dbPath | stage == Stage1 ]
                               ++ [ "$@" ]

-- | Given a 'String' replace charaters '.' and '-' by underscores ('_') so that
-- the resulting 'String' is a valid C preprocessor identifier.
cppify :: String -> String
cppify = replaceEq '-' '_' . replaceEq '.' '_'

-- | Generate @ghcplatform.h@ header.
generateGhcPlatformH :: Expr String
generateGhcPlatformH = do
    trackGenerateHs
    hostPlatform   <- getSetting HostPlatform
    hostArch       <- getSetting HostArch
    hostOs         <- getSetting HostOs
    hostVendor     <- getSetting HostVendor
    targetPlatform <- getSetting TargetPlatform
    targetArch     <- getSetting TargetArch
    targetOs       <- getSetting TargetOs
    targetVendor   <- getSetting TargetVendor
    ghcUnreg       <- getFlag    GhcUnregisterised
    return . unlines $
        [ "#if !defined(__GHCPLATFORM_H__)"
        , "#define __GHCPLATFORM_H__"
        , ""
        , "#define BuildPlatform_TYPE  " ++ cppify hostPlatform
        , "#define HostPlatform_TYPE   " ++ cppify targetPlatform
        , ""
        , "#define " ++ cppify hostPlatform   ++ "_BUILD 1"
        , "#define " ++ cppify targetPlatform ++ "_HOST 1"
        , ""
        , "#define " ++ hostArch   ++ "_BUILD_ARCH 1"
        , "#define " ++ targetArch ++ "_HOST_ARCH 1"
        , "#define BUILD_ARCH " ++ show hostArch
        , "#define HOST_ARCH "  ++ show targetArch
        , ""
        , "#define " ++ hostOs   ++ "_BUILD_OS 1"
        , "#define " ++ targetOs ++ "_HOST_OS 1"
        , "#define BUILD_OS " ++ show hostOs
        , "#define HOST_OS "  ++ show targetOs
        , ""
        , "#define " ++ hostVendor   ++ "_BUILD_VENDOR 1"
        , "#define " ++ targetVendor ++ "_HOST_VENDOR 1"
        , "#define BUILD_VENDOR " ++ show hostVendor
        , "#define HOST_VENDOR "  ++ show targetVendor
        , ""
        , "/* These TARGET macros are for backwards compatibility... DO NOT USE! */"
        , "#define TargetPlatform_TYPE " ++ cppify targetPlatform
        , "#define " ++ cppify targetPlatform ++ "_TARGET 1"
        , "#define " ++ targetArch ++ "_TARGET_ARCH 1"
        , "#define TARGET_ARCH " ++ show targetArch
        , "#define " ++ targetOs ++ "_TARGET_OS 1"
        , "#define TARGET_OS " ++ show targetOs
        , "#define " ++ targetVendor ++ "_TARGET_VENDOR 1" ]
        ++
        [ "#define UnregisterisedCompiler 1" | ghcUnreg ]
        ++
        [ "\n#endif /* __GHCPLATFORM_H__ */" ]

generateSettings :: Expr String
generateSettings = do
    ctx <- getContext
    settings <- traverse sequence $
        [ ("GCC extra via C opts", expr $ lookupValueOrError configFile "gcc-extra-via-c-opts")
        , ("C compiler command", expr $ settingsFileSetting SettingsFileSetting_CCompilerCommand)
        , ("C compiler flags", expr $ settingsFileSetting SettingsFileSetting_CCompilerFlags)
        , ("C compiler link flags", expr $ settingsFileSetting SettingsFileSetting_CCompilerLinkFlags)
        , ("C compiler supports -no-pie", expr $ settingsFileSetting SettingsFileSetting_CCompilerSupportsNoPie)
        , ("Haskell CPP command", expr $ settingsFileSetting SettingsFileSetting_HaskellCPPCommand)
        , ("Haskell CPP flags", expr $ settingsFileSetting SettingsFileSetting_HaskellCPPFlags)
        , ("ld command", expr $ settingsFileSetting SettingsFileSetting_LdCommand)
        , ("ld flags", expr $ settingsFileSetting SettingsFileSetting_LdFlags)
        , ("ld supports compact unwind", expr $ lookupValueOrError configFile "ld-has-no-compact-unwind")
        , ("ld supports build-id", expr $ lookupValueOrError configFile "ld-has-build-id")
        , ("ld supports filelist", expr $ lookupValueOrError configFile "ld-has-filelist")
        , ("ld is GNU ld", expr $ lookupValueOrError configFile "ld-is-gnu-ld")
        , ("ar command", expr $ settingsFileSetting SettingsFileSetting_ArCommand)
        , ("ar flags", expr $ lookupValueOrError configFile "ar-args")
        , ("ar supports at file", expr $ yesNo <$> flag ArSupportsAtFile)
        , ("ranlib command", expr $ settingsFileSetting SettingsFileSetting_RanlibCommand)
        , ("touch command", expr $ settingsFileSetting SettingsFileSetting_TouchCommand)
        , ("dllwrap command", expr $ settingsFileSetting SettingsFileSetting_DllWrapCommand)
        , ("windres command", expr $ settingsFileSetting SettingsFileSetting_WindresCommand)
        , ("libtool command", expr $ settingsFileSetting SettingsFileSetting_LibtoolCommand)
        , ("unlit command", ("$topdir/bin/" <>) <$> expr (programName (ctx { Context.package = unlit })))
        , ("cross compiling", expr $ yesNo <$> flag CrossCompiling)
        , ("target platform string", getSetting TargetPlatform)
        , ("target os", expr $ lookupValueOrError configFile "haskell-target-os")
        , ("target arch", expr $ lookupValueOrError configFile "haskell-target-arch")
        , ("target word size", expr $ lookupValueOrError configFile "target-word-size")
        , ("target has GNU nonexec stack", expr $ lookupValueOrError configFile "haskell-have-gnu-nonexec-stack")
        , ("target has .ident directive", expr $ lookupValueOrError configFile "haskell-have-ident-directive")
        , ("target has subsections via symbols", expr $ lookupValueOrError configFile "haskell-have-subsections-via-symbols")
        , ("target has RTS linker", expr $ lookupValueOrError configFile "haskell-have-rts-linker")
        , ("Unregisterised", expr $ yesNo <$> flag GhcUnregisterised)
        , ("LLVM llc command", expr $ settingsFileSetting SettingsFileSetting_LlcCommand)
        , ("LLVM opt command", expr $ settingsFileSetting SettingsFileSetting_OptCommand)
        , ("LLVM clang command", expr $ settingsFileSetting SettingsFileSetting_ClangCommand)

        , ("integer library", pkgName <$> getIntegerPackage)
        , ("Use interpreter", expr $ yesNo <$> ghcWithInterpreter)
        , ("Use native code generator", expr $ yesNo <$> ghcWithNativeCodeGen)
        , ("Support SMP", expr $ yesNo <$> ghcWithSMP)
        , ("RTS ways", unwords . map show <$> getRtsWays)
        , ("Tables next to code", expr $ yesNo <$> ghcEnableTablesNextToCode)
        , ("Leading underscore", expr $ yesNo <$> flag LeadingUnderscore)
        , ("Use LibFFI", expr $ yesNo <$> useLibFFIForAdjustors)
        , ("Use Threads", yesNo . any (wayUnit Threaded) <$> getRtsWays)
        , ("Use Debugging", expr $ yesNo . ghcDebugged <$> flavour)
        , ("RTS expects libdw", yesNo <$> getFlag WithLibdw)
        ]
    let showTuple (k, v) = "(" ++ show k ++ ", " ++ show v ++ ")"
    pure $ case settings of
        [] -> "[]"
        s : ss -> unlines $
            ("[" ++ showTuple s)
            : ((\s' -> "," ++ showTuple s') <$> ss)
            ++ ["]"]


-- | Generate @Config.hs@ files.
generateConfigHs :: Expr String
generateConfigHs = do
    trackGenerateHs
    cProjectName        <- getSetting ProjectName
    cProjectGitCommitId <- getSetting ProjectGitCommitId
    cProjectVersion     <- getSetting ProjectVersion
    cProjectVersionInt  <- getSetting ProjectVersionInt
    cProjectPatchLevel  <- getSetting ProjectPatchLevel
    cProjectPatchLevel1 <- getSetting ProjectPatchLevel1
    cProjectPatchLevel2 <- getSetting ProjectPatchLevel2
    cBooterVersion      <- getSetting GhcVersion
    return $ unlines
        [ "{-# LANGUAGE CPP #-}"
        , "module Config where"
        , ""
        , "import GhcPrelude"
        , ""
        , "#include \"ghc_boot_platform.h\""
        , ""
        , "cBuildPlatformString :: String"
        , "cBuildPlatformString = BuildPlatform_NAME"
        , "cHostPlatformString :: String"
        , "cHostPlatformString = HostPlatform_NAME"
        , ""
        , "cProjectName          :: String"
        , "cProjectName          = " ++ show cProjectName
        , "cProjectGitCommitId   :: String"
        , "cProjectGitCommitId   = " ++ show cProjectGitCommitId
        , "cProjectVersion       :: String"
        , "cProjectVersion       = " ++ show cProjectVersion
        , "cProjectVersionInt    :: String"
        , "cProjectVersionInt    = " ++ show cProjectVersionInt
        , "cProjectPatchLevel    :: String"
        , "cProjectPatchLevel    = " ++ show cProjectPatchLevel
        , "cProjectPatchLevel1   :: String"
        , "cProjectPatchLevel1   = " ++ show cProjectPatchLevel1
        , "cProjectPatchLevel2   :: String"
        , "cProjectPatchLevel2   = " ++ show cProjectPatchLevel2
        , "cBooterVersion        :: String"
        , "cBooterVersion        = " ++ show cBooterVersion
        , "cStage                :: String"
        , "cStage                = show (STAGE :: Int)"
        ]

-- | Generate @ghcautoconf.h@ header.
generateGhcAutoconfH :: Expr String
generateGhcAutoconfH = do
    trackGenerateHs
    configHContents  <- expr $ map undefinePackage <$> readFileLines configH
    tablesNextToCode <- expr ghcEnableTablesNextToCode
    ghcUnreg         <- getFlag    GhcUnregisterised
    ccLlvmBackend    <- getSetting CcLlvmBackend
    ccClangBackend   <- getSetting CcClangBackend
    return . unlines $
        [ "#if !defined(__GHCAUTOCONF_H__)"
        , "#define __GHCAUTOCONF_H__" ]
        ++ configHContents ++
        [ "\n#define TABLES_NEXT_TO_CODE 1" | tablesNextToCode && not ghcUnreg ]
        ++
        [ "\n#define llvm_CC_FLAVOR 1"      | ccLlvmBackend == "1" ]
        ++
        [ "\n#define clang_CC_FLAVOR 1"     | ccClangBackend == "1" ]
        ++
        [ "#endif /* __GHCAUTOCONF_H__ */" ]
  where
    undefinePackage s
        | "#define PACKAGE_" `isPrefixOf` s
            = "/* #undef " ++ takeWhile (/=' ') (drop 8 s) ++ " */"
        | otherwise = s

-- | Generate @ghc_boot_platform.h@ headers.
generateGhcBootPlatformH :: Expr String
generateGhcBootPlatformH = do
    trackGenerateHs
    stage <- getStage
    let chooseSetting x y = getSetting $ if stage == Stage0 then x else y
    buildPlatform  <- chooseSetting BuildPlatform HostPlatform
    buildArch      <- chooseSetting BuildArch     HostArch
    buildOs        <- chooseSetting BuildOs       HostOs
    buildVendor    <- chooseSetting BuildVendor   HostVendor
    hostPlatform   <- chooseSetting HostPlatform  TargetPlatform
    hostArch       <- chooseSetting HostArch      TargetArch
    hostOs         <- chooseSetting HostOs        TargetOs
    hostVendor     <- chooseSetting HostVendor    TargetVendor
    targetPlatform <- getSetting TargetPlatform
    targetArch     <- getSetting TargetArch
    llvmTarget     <- getSetting LlvmTarget
    targetOs       <- getSetting TargetOs
    targetVendor   <- getSetting TargetVendor
    return $ unlines
        [ "#if !defined(__PLATFORM_H__)"
        , "#define __PLATFORM_H__"
        , ""
        , "#define BuildPlatform_NAME  " ++ show buildPlatform
        , "#define HostPlatform_NAME   " ++ show hostPlatform
        , ""
        , "#define " ++ cppify buildPlatform  ++ "_BUILD 1"
        , "#define " ++ cppify hostPlatform   ++ "_HOST 1"
        , "#define " ++ cppify targetPlatform ++ "_TARGET 1"
        , ""
        , "#define " ++ buildArch  ++ "_BUILD_ARCH 1"
        , "#define " ++ hostArch   ++ "_HOST_ARCH 1"
        , "#define " ++ targetArch ++ "_TARGET_ARCH 1"
        , "#define BUILD_ARCH "  ++ show buildArch
        , "#define HOST_ARCH "   ++ show hostArch
        , "#define TARGET_ARCH " ++ show targetArch
        , "#define LLVM_TARGET " ++ show llvmTarget
        , ""
        , "#define " ++ buildOs  ++ "_BUILD_OS 1"
        , "#define " ++ hostOs   ++ "_HOST_OS 1"
        , "#define " ++ targetOs ++ "_TARGET_OS 1"
        , "#define BUILD_OS "  ++ show buildOs
        , "#define HOST_OS "   ++ show hostOs
        , "#define TARGET_OS " ++ show targetOs
        , ""
        , "#define " ++ buildVendor  ++ "_BUILD_VENDOR 1"
        , "#define " ++ hostVendor   ++ "_HOST_VENDOR 1"
        , "#define " ++ targetVendor ++ "_TARGET_VENDOR  1"
        , "#define BUILD_VENDOR "  ++ show buildVendor
        , "#define HOST_VENDOR "   ++ show hostVendor
        , "#define TARGET_VENDOR " ++ show targetVendor
        , ""
        , "#endif /* __PLATFORM_H__ */" ]

-- | Generate @ghcversion.h@ header.
generateGhcVersionH :: Expr String
generateGhcVersionH = do
    trackGenerateHs
    version     <- getSetting ProjectVersionInt
    patchLevel1 <- getSetting ProjectPatchLevel1
    patchLevel2 <- getSetting ProjectPatchLevel2
    return . unlines $
        [ "#if !defined(__GHCVERSION_H__)"
        , "#define __GHCVERSION_H__"
        , ""
        , "#if !defined(__GLASGOW_HASKELL__)"
        , "# define __GLASGOW_HASKELL__ " ++ version
        , "#endif"
        , ""]
        ++
        [ "#define __GLASGOW_HASKELL_PATCHLEVEL1__ " ++ patchLevel1 | patchLevel1 /= "" ]
        ++
        [ "#define __GLASGOW_HASKELL_PATCHLEVEL2__ " ++ patchLevel2 | patchLevel2 /= "" ]
        ++
        [ ""
        , "#define MIN_VERSION_GLASGOW_HASKELL(ma,mi,pl1,pl2) (\\"
        , "   ((ma)*100+(mi)) <  __GLASGOW_HASKELL__ || \\"
        , "   ((ma)*100+(mi)) == __GLASGOW_HASKELL__    \\"
        , "          && (pl1) <  __GLASGOW_HASKELL_PATCHLEVEL1__ || \\"
        , "   ((ma)*100+(mi)) == __GLASGOW_HASKELL__    \\"
        , "          && (pl1) == __GLASGOW_HASKELL_PATCHLEVEL1__ \\"
        , "          && (pl2) <= __GLASGOW_HASKELL_PATCHLEVEL2__ )"
        , ""
        , "#endif /* __GHCVERSION_H__ */" ]

-- | Generate @Version.hs@ files.
generateVersionHs :: Expr String
generateVersionHs = do
    trackGenerateHs
    projectVersion <- getSetting ProjectVersion
    targetOs       <- getSetting TargetOs
    targetArch     <- getSetting TargetArch
    return $ unlines
        [ "module Version where"
        , "version, targetOS, targetARCH :: String"
        , "version    = " ++ show projectVersion
        , "targetOS   = " ++ show targetOs
        , "targetARCH = " ++ show targetArch ]