content: {-# LANGUAGE FlexibleContexts #-}
  {-# LANGUAGE RankNTypes #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Distribution.Simple.LHC
  -- Copyright   :  Isaac Jones 2003-2007
  -- License     :  BSD3
  --
  -- Maintainer  :  cabal-devel@haskell.org
  -- Portability :  portable
  --
  -- This is a fairly large module. It contains most of the GHC-specific code for
  -- configuring, building and installing packages. It also exports a function
  -- for finding out what packages are already installed. Configuring involves
  -- finding the @ghc@ and @ghc-pkg@ programs, finding what language extensions
  -- this version of ghc supports and returning a 'Compiler' value.
  --
  -- 'getInstalledPackages' involves calling the @ghc-pkg@ program to find out
  -- what packages are installed.
  --
  -- Building is somewhat complex as there is quite a bit of information to take
  -- into account. We have to build libs and programs, possibly for profiling and
  -- shared libs. We have to support building libraries that will be usable by
  -- GHCi and also ghc's @-split-objs@ feature. We have to compile any C files
  -- using ghc. Linking, especially for @split-objs@ is remarkably complex,
  -- partly because there tend to be 1,000's of @.o@ files and this can often be
  -- more than we can pass to the @ld@ or @ar@ programs in one go.
  --
  -- Installing for libs and exes involves finding the right files and copying
  -- them to the right places. One of the more tricky things about this module is
  -- remembering the layout of files in the build directory (which is not
  -- explicitly documented) and thus what search dirs are used for various kinds
  -- of files.
  
  module Distribution.Simple.LHC (
          configure, getInstalledPackages,
          buildLib, buildExe,
          installLib, installExe,
          registerPackage,
          hcPkgInfo,
          ghcOptions,
          ghcVerbosityOptions
   ) where
  
  import Prelude ()
  import Distribution.Compat.Prelude
  
  import Distribution.Types.UnqualComponentName
  import Distribution.PackageDescription as PD hiding (Flag)
  import Distribution.InstalledPackageInfo
  import qualified Distribution.InstalledPackageInfo as InstalledPackageInfo
  import Distribution.Simple.PackageIndex
  import qualified Distribution.Simple.PackageIndex as PackageIndex
  import Distribution.Simple.LocalBuildInfo
  import Distribution.Simple.BuildPaths
  import Distribution.Simple.Utils
  import Distribution.Package
  import qualified Distribution.ModuleName as ModuleName
  import Distribution.Simple.Program
  import qualified Distribution.Simple.Program.HcPkg as HcPkg
  import Distribution.Simple.Compiler
  import Distribution.Version
  import Distribution.Verbosity
  import Distribution.Text
  import Distribution.Compat.Exception
  import Distribution.System
  import Language.Haskell.Extension
  
  import qualified Data.Map as Map ( empty )
  import System.Directory         ( removeFile, renameFile,
                                    getDirectoryContents, doesFileExist,
                                    getTemporaryDirectory )
  import System.FilePath          ( (</>), (<.>), takeExtension,
                                    takeDirectory, replaceExtension )
  import System.IO (hClose, hPutStrLn)
  
  -- -----------------------------------------------------------------------------
  -- Configuring
  
  configure :: Verbosity -> Maybe FilePath -> Maybe FilePath
            -> ProgramDb -> IO (Compiler, Maybe Platform, ProgramDb)
  configure verbosity hcPath hcPkgPath progdb = do
  
    (lhcProg, lhcVersion, progdb') <-
      requireProgramVersion verbosity lhcProgram
        (orLaterVersion (mkVersion [0,7]))
        (userMaybeSpecifyPath "lhc" hcPath progdb)
  
    (lhcPkgProg, lhcPkgVersion, progdb'') <-
      requireProgramVersion verbosity lhcPkgProgram
        (orLaterVersion (mkVersion [0,7]))
        (userMaybeSpecifyPath "lhc-pkg" hcPkgPath progdb')
  
    when (lhcVersion /= lhcPkgVersion) $ die' verbosity $
         "Version mismatch between lhc and lhc-pkg: "
      ++ programPath lhcProg ++ " is version " ++ display lhcVersion ++ " "
      ++ programPath lhcPkgProg ++ " is version " ++ display lhcPkgVersion
  
    languages  <- getLanguages  verbosity lhcProg
    extensions <- getExtensions verbosity lhcProg
  
    let comp = Compiler {
          compilerId             = CompilerId LHC lhcVersion,
          compilerAbiTag         = NoAbiTag,
          compilerCompat         = [],
          compilerLanguages      = languages,
          compilerExtensions     = extensions,
          compilerProperties     = Map.empty
        }
        progdb''' = configureToolchain lhcProg progdb'' -- configure gcc and ld
        compPlatform = Nothing
    return (comp, compPlatform, progdb''')
  
  -- | Adjust the way we find and configure gcc and ld
  --
  configureToolchain :: ConfiguredProgram -> ProgramDb
                                          -> ProgramDb
  configureToolchain lhcProg =
      addKnownProgram gccProgram {
        programFindLocation = findProg gccProgram (baseDir </> "gcc.exe"),
        programPostConf     = configureGcc
      }
    . addKnownProgram ldProgram {
        programFindLocation = findProg ldProgram (gccLibDir </> "ld.exe"),
        programPostConf     = configureLd
      }
    where
      compilerDir = takeDirectory (programPath lhcProg)
      baseDir     = takeDirectory compilerDir
      gccLibDir      = baseDir </> "gcc-lib"
      includeDir  = baseDir </> "include" </> "mingw"
      isWindows   = case buildOS of Windows -> True; _ -> False
  
      -- on Windows finding and configuring ghc's gcc and ld is a bit special
      findProg :: Program -> FilePath
               -> Verbosity -> ProgramSearchPath
               -> IO (Maybe (FilePath, [FilePath]))
      findProg prog location | isWindows = \verbosity searchpath -> do
          exists <- doesFileExist location
          if exists then return (Just (location, []))
                    else do warn verbosity ("Couldn't find " ++ programName prog ++ " where I expected it. Trying the search path.")
                            programFindLocation prog verbosity searchpath
        | otherwise = programFindLocation prog
  
      configureGcc :: Verbosity -> ConfiguredProgram -> NoCallStackIO ConfiguredProgram
      configureGcc
        | isWindows = \_ gccProg -> case programLocation gccProg of
            -- if it's found on system then it means we're using the result
            -- of programFindLocation above rather than a user-supplied path
            -- that means we should add this extra flag to tell ghc's gcc
            -- where it lives and thus where gcc can find its various files:
            FoundOnSystem {} -> return gccProg {
                                  programDefaultArgs = ["-B" ++ gccLibDir,
                                                        "-I" ++ includeDir]
                                }
            UserSpecified {} -> return gccProg
        | otherwise = \_ gccProg -> return gccProg
  
      -- we need to find out if ld supports the -x flag
      configureLd :: Verbosity -> ConfiguredProgram -> IO ConfiguredProgram
      configureLd verbosity ldProg = do
        tempDir <- getTemporaryDirectory
        ldx <- withTempFile tempDir ".c" $ \testcfile testchnd ->
               withTempFile tempDir ".o" $ \testofile testohnd -> do
                 hPutStrLn testchnd "int foo() { return 0; }"
                 hClose testchnd; hClose testohnd
                 runProgram verbosity lhcProg ["-c", testcfile,
                                                     "-o", testofile]
                 withTempFile tempDir ".o" $ \testofile' testohnd' ->
                   do
                     hClose testohnd'
                     _ <- getProgramOutput verbosity ldProg
                       ["-x", "-r", testofile, "-o", testofile']
                     return True
                   `catchIO`   (\_ -> return False)
                   `catchExit` (\_ -> return False)
        if ldx
          then return ldProg { programDefaultArgs = ["-x"] }
          else return ldProg
  
  getLanguages :: Verbosity -> ConfiguredProgram -> NoCallStackIO [(Language, Flag)]
  getLanguages _ _ = return [(Haskell98, "")]
  --FIXME: does lhc support -XHaskell98 flag? from what version?
  
  getExtensions :: Verbosity -> ConfiguredProgram -> IO [(Extension, Flag)]
  getExtensions verbosity lhcProg = do
      exts <- rawSystemStdout verbosity (programPath lhcProg)
                ["--supported-languages"]
      -- GHC has the annoying habit of inverting some of the extensions
      -- so we have to try parsing ("No" ++ ghcExtensionName) first
      let readExtension str = do
            ext <- simpleParse ("No" ++ str)
            case ext of
              UnknownExtension _ -> simpleParse str
              _                  -> return ext
      return $ [ (ext, "-X" ++ display ext)
               | Just ext <- map readExtension (lines exts) ]
  
  getInstalledPackages :: Verbosity -> PackageDBStack -> ProgramDb
                       -> IO InstalledPackageIndex
  getInstalledPackages verbosity packagedbs progdb = do
    checkPackageDbStack verbosity packagedbs
    pkgss <- getInstalledPackages' lhcPkg verbosity packagedbs progdb
    let indexes = [ PackageIndex.fromList (map (substTopDir topDir) pkgs)
                  | (_, pkgs) <- pkgss ]
    return $! (mconcat indexes)
  
    where
      -- On Windows, various fields have $topdir/foo rather than full
      -- paths. We need to substitute the right value in so that when
      -- we, for example, call gcc, we have proper paths to give it
      Just ghcProg = lookupProgram lhcProgram progdb
      Just lhcPkg  = lookupProgram lhcPkgProgram progdb
      compilerDir  = takeDirectory (programPath ghcProg)
      topDir       = takeDirectory compilerDir
  
  checkPackageDbStack :: Verbosity -> PackageDBStack -> IO ()
  checkPackageDbStack _ (GlobalPackageDB:rest)
    | GlobalPackageDB `notElem` rest = return ()
  checkPackageDbStack verbosity _ =
    die' verbosity $
          "GHC.getInstalledPackages: the global package db must be "
       ++ "specified first and cannot be specified multiple times"
  
  -- | Get the packages from specific PackageDBs, not cumulative.
  --
  getInstalledPackages' :: ConfiguredProgram -> Verbosity
                        -> [PackageDB] -> ProgramDb
                        -> IO [(PackageDB, [InstalledPackageInfo])]
  getInstalledPackages' lhcPkg verbosity packagedbs progdb
    =
    sequenceA
      [ do str <- getDbProgramOutput verbosity lhcPkgProgram progdb
                    ["dump", packageDbGhcPkgFlag packagedb]
             `catchExit` \_ -> die' verbosity $ "ghc-pkg dump failed"
           case parsePackages str of
             Left ok -> return (packagedb, ok)
             _       -> die' verbosity "failed to parse output of 'ghc-pkg dump'"
      | packagedb <- packagedbs ]
  
    where
      parsePackages str =
        let parsed = map parseInstalledPackageInfo (splitPkgs str)
         in case [ msg | ParseFailed msg <- parsed ] of
              []   -> Left [ pkg | ParseOk _ pkg <- parsed ]
              msgs -> Right msgs
  
      splitPkgs :: String -> [String]
      splitPkgs = map unlines . splitWith ("---" ==) . lines
        where
          splitWith :: (a -> Bool) -> [a] -> [[a]]
          splitWith p xs = ys : case zs of
                             []   -> []
                             _:ws -> splitWith p ws
            where (ys,zs) = break p xs
  
      packageDbGhcPkgFlag GlobalPackageDB          = "--global"
      packageDbGhcPkgFlag UserPackageDB            = "--user"
      packageDbGhcPkgFlag (SpecificPackageDB path) = "--" ++ packageDbFlag ++ "=" ++ path
  
      packageDbFlag
        | programVersion lhcPkg < Just (mkVersion [7,5])
        = "package-conf"
        | otherwise
        = "package-db"
  
  
  substTopDir :: FilePath -> InstalledPackageInfo -> InstalledPackageInfo
  substTopDir topDir ipo
   = ipo {
         InstalledPackageInfo.importDirs
             = map f (InstalledPackageInfo.importDirs ipo),
         InstalledPackageInfo.libraryDirs
             = map f (InstalledPackageInfo.libraryDirs ipo),
         InstalledPackageInfo.includeDirs
             = map f (InstalledPackageInfo.includeDirs ipo),
         InstalledPackageInfo.frameworkDirs
             = map f (InstalledPackageInfo.frameworkDirs ipo),
         InstalledPackageInfo.haddockInterfaces
             = map f (InstalledPackageInfo.haddockInterfaces ipo),
         InstalledPackageInfo.haddockHTMLs
             = map f (InstalledPackageInfo.haddockHTMLs ipo)
     }
      where f ('$':'t':'o':'p':'d':'i':'r':rest) = topDir ++ rest
            f x = x
  
  -- -----------------------------------------------------------------------------
  -- Building
  
  -- | Build a library with LHC.
  --
  buildLib :: Verbosity -> PackageDescription -> LocalBuildInfo
                        -> Library            -> ComponentLocalBuildInfo -> IO ()
  buildLib verbosity pkg_descr lbi lib clbi = do
    let lib_name = componentUnitId clbi
        pref = componentBuildDir lbi clbi
        pkgid = packageId pkg_descr
        runGhcProg = runDbProgram verbosity lhcProgram (withPrograms lbi)
        ifVanillaLib forceVanilla = when (forceVanilla || withVanillaLib lbi)
        ifProfLib = when (withProfLib lbi)
        ifSharedLib = when (withSharedLib lbi)
        ifGHCiLib = when (withGHCiLib lbi && withVanillaLib lbi)
  
    libBi <- hackThreadedFlag verbosity
               (compiler lbi) (withProfLib lbi) (libBuildInfo lib)
  
    let libTargetDir = pref
        forceVanillaLib = EnableExtension TemplateHaskell `elem` allExtensions libBi
        -- TH always needs vanilla libs, even when building for profiling
  
    createDirectoryIfMissingVerbose verbosity True libTargetDir
    -- TODO: do we need to put hs-boot files into place for mutually recursive modules?
    let ghcArgs =
               ["-package-name", display pkgid ]
            ++ constructGHCCmdLine lbi libBi clbi libTargetDir verbosity
            ++ map display (allLibModules lib clbi)
        lhcWrap x = ["--build-library", "--ghc-opts=" ++ unwords x]
        ghcArgsProf = ghcArgs
            ++ ["-prof",
                "-hisuf", "p_hi",
                "-osuf", "p_o"
               ]
            ++ hcProfOptions GHC libBi
        ghcArgsShared = ghcArgs
            ++ ["-dynamic",
                "-hisuf", "dyn_hi",
                "-osuf", "dyn_o", "-fPIC"
               ]
            ++ hcSharedOptions GHC libBi
    unless (null (allLibModules lib clbi)) $
      do ifVanillaLib forceVanillaLib (runGhcProg $ lhcWrap ghcArgs)
         ifProfLib (runGhcProg $ lhcWrap ghcArgsProf)
         ifSharedLib (runGhcProg $ lhcWrap ghcArgsShared)
  
    -- build any C sources
    unless (null (cSources libBi)) $ do
       info verbosity "Building C Sources..."
       sequence_ [do let (odir,args) = constructCcCmdLine lbi libBi clbi pref
                                                          filename verbosity
                     createDirectoryIfMissingVerbose verbosity True odir
                     runGhcProg args
                     ifSharedLib (runGhcProg (args ++ ["-fPIC", "-osuf dyn_o"]))
                 | filename <- cSources libBi]
  
    -- link:
    info verbosity "Linking..."
    let cObjs = map (`replaceExtension` objExtension) (cSources libBi)
        cSharedObjs = map (`replaceExtension` ("dyn_" ++ objExtension)) (cSources libBi)
        cid = compilerId (compiler lbi)
        vanillaLibFilePath = libTargetDir </> mkLibName           lib_name
        profileLibFilePath = libTargetDir </> mkProfLibName       lib_name
        sharedLibFilePath  = libTargetDir </> mkSharedLibName cid lib_name
        ghciLibFilePath    = libTargetDir </> mkGHCiLibName       lib_name
  
    stubObjs <- fmap catMaybes $ sequenceA
      [ findFileWithExtension [objExtension] [libTargetDir]
          (ModuleName.toFilePath x ++"_stub")
      | x <- allLibModules lib clbi ]
    stubProfObjs <- fmap catMaybes $ sequenceA
      [ findFileWithExtension ["p_" ++ objExtension] [libTargetDir]
          (ModuleName.toFilePath x ++"_stub")
      | x <- allLibModules lib clbi ]
    stubSharedObjs <- fmap catMaybes $ sequenceA
      [ findFileWithExtension ["dyn_" ++ objExtension] [libTargetDir]
          (ModuleName.toFilePath x ++"_stub")
      | x <- allLibModules lib clbi ]
  
    hObjs     <- getHaskellObjects lib lbi clbi
                      pref objExtension True
    hProfObjs <-
      if (withProfLib lbi)
              then getHaskellObjects lib lbi clbi
                      pref ("p_" ++ objExtension) True
              else return []
    hSharedObjs <-
      if (withSharedLib lbi)
              then getHaskellObjects lib lbi clbi
                      pref ("dyn_" ++ objExtension) False
              else return []
  
    unless (null hObjs && null cObjs && null stubObjs) $ do
      -- first remove library files if they exists
      sequence_
        [ removeFile libFilePath `catchIO` \_ -> return ()
        | libFilePath <- [vanillaLibFilePath, profileLibFilePath
                         ,sharedLibFilePath,  ghciLibFilePath] ]
  
      let arVerbosity | verbosity >= deafening = "v"
                      | verbosity >= normal = ""
                      | otherwise = "c"
          arArgs = ["q"++ arVerbosity]
              ++ [vanillaLibFilePath]
          arObjArgs =
                 hObjs
              ++ map (pref </>) cObjs
              ++ stubObjs
          arProfArgs = ["q"++ arVerbosity]
              ++ [profileLibFilePath]
          arProfObjArgs =
                 hProfObjs
              ++ map (pref </>) cObjs
              ++ stubProfObjs
          ldArgs = ["-r"]
              ++ ["-o", ghciLibFilePath <.> "tmp"]
          ldObjArgs =
                 hObjs
              ++ map (pref </>) cObjs
              ++ stubObjs
          ghcSharedObjArgs =
                 hSharedObjs
              ++ map (pref </>) cSharedObjs
              ++ stubSharedObjs
          -- After the relocation lib is created we invoke ghc -shared
          -- with the dependencies spelled out as -package arguments
          -- and ghc invokes the linker with the proper library paths
          ghcSharedLinkArgs =
              [ "-no-auto-link-packages",
                "-shared",
                "-dynamic",
                "-o", sharedLibFilePath ]
              ++ ghcSharedObjArgs
              ++ ["-package-name", display pkgid ]
              ++ ghcPackageFlags lbi clbi
              ++ ["-l"++extraLib | extraLib <- extraLibs libBi]
              ++ ["-L"++extraLibDir | extraLibDir <- extraLibDirs libBi]
  
          runLd ldLibName args = do
            exists <- doesFileExist ldLibName
              -- This method is called iteratively by xargs. The
              -- output goes to <ldLibName>.tmp, and any existing file
              -- named <ldLibName> is included when linking. The
              -- output is renamed to <lib_name>.
            runDbProgram verbosity ldProgram (withPrograms lbi)
              (args ++ if exists then [ldLibName] else [])
            renameFile (ldLibName <.> "tmp") ldLibName
  
          runAr = runDbProgram verbosity arProgram (withPrograms lbi)
  
           --TODO: discover this at configure time or runtime on Unix
           -- The value is 32k on Windows and POSIX specifies a minimum of 4k
           -- but all sensible Unixes use more than 4k.
           -- we could use getSysVar ArgumentLimit but that's in the Unix lib
          maxCommandLineSize = 30 * 1024
  
      ifVanillaLib False $ xargs maxCommandLineSize
        runAr arArgs arObjArgs
  
      ifProfLib $ xargs maxCommandLineSize
        runAr arProfArgs arProfObjArgs
  
      ifGHCiLib $ xargs maxCommandLineSize
        (runLd ghciLibFilePath) ldArgs ldObjArgs
  
      ifSharedLib $ runGhcProg ghcSharedLinkArgs
  
  
  -- | Build an executable with LHC.
  --
  buildExe :: Verbosity -> PackageDescription -> LocalBuildInfo
                        -> Executable         -> ComponentLocalBuildInfo -> IO ()
  buildExe verbosity _pkg_descr lbi
    exe@Executable { exeName = exeName', modulePath = modPath } clbi = do
    let exeName'' = unUnqualComponentName exeName'
    let pref = buildDir lbi
        runGhcProg = runDbProgram verbosity lhcProgram (withPrograms lbi)
  
    exeBi <- hackThreadedFlag verbosity
               (compiler lbi) (withProfExe lbi) (buildInfo exe)
  
    -- exeNameReal, the name that GHC really uses (with .exe on Windows)
    let exeNameReal = exeName'' <.>
                      (if null $ takeExtension exeName'' then exeExtension else "")
  
    let targetDir = pref </> exeName''
    let exeDir    = targetDir </> (exeName'' ++ "-tmp")
    createDirectoryIfMissingVerbose verbosity True targetDir
    createDirectoryIfMissingVerbose verbosity True exeDir
    -- TODO: do we need to put hs-boot files into place for mutually recursive modules?
    -- FIX: what about exeName.hi-boot?
  
    -- build executables
    unless (null (cSources exeBi)) $ do
     info verbosity "Building C Sources."
     sequence_ [do let (odir,args) = constructCcCmdLine lbi exeBi clbi
                                            exeDir filename verbosity
                   createDirectoryIfMissingVerbose verbosity True odir
                   runGhcProg args
               | filename <- cSources exeBi]
  
    srcMainFile <- findFile (exeDir : hsSourceDirs exeBi) modPath
  
    let cObjs = map (`replaceExtension` objExtension) (cSources exeBi)
    let lhcWrap x = ("--ghc-opts\"":x) ++ ["\""]
    let binArgs linkExe profExe =
               (if linkExe
                   then ["-o", targetDir </> exeNameReal]
                   else ["-c"])
            ++ constructGHCCmdLine lbi exeBi clbi exeDir verbosity
            ++ [exeDir </> x | x <- cObjs]
            ++ [srcMainFile]
            ++ ["-optl" ++ opt | opt <- PD.ldOptions exeBi]
            ++ ["-l"++lib | lib <- extraLibs exeBi]
            ++ ["-L"++extraLibDir | extraLibDir <- extraLibDirs exeBi]
            ++ concat [["-framework", f] | f <- PD.frameworks exeBi]
            ++ if profExe
                  then ["-prof",
                        "-hisuf", "p_hi",
                        "-osuf", "p_o"
                       ] ++ hcProfOptions GHC exeBi
                  else []
  
    -- For building exe's for profiling that use TH we actually
    -- have to build twice, once without profiling and the again
    -- with profiling. This is because the code that TH needs to
    -- run at compile time needs to be the vanilla ABI so it can
    -- be loaded up and run by the compiler.
    when (withProfExe lbi && EnableExtension TemplateHaskell `elem` allExtensions exeBi)
       (runGhcProg $ lhcWrap (binArgs False False))
  
    runGhcProg (binArgs True (withProfExe lbi))
  
  -- | Filter the "-threaded" flag when profiling as it does not
  --   work with ghc-6.8 and older.
  hackThreadedFlag :: Verbosity -> Compiler -> Bool -> BuildInfo -> IO BuildInfo
  hackThreadedFlag verbosity comp prof bi
    | not mustFilterThreaded = return bi
    | otherwise              = do
      warn verbosity $ "The ghc flag '-threaded' is not compatible with "
                    ++ "profiling in ghc-6.8 and older. It will be disabled."
      return bi { options = filterHcOptions (/= "-threaded") (options bi) }
    where
      mustFilterThreaded = prof && compilerVersion comp < mkVersion [6, 10]
                        && "-threaded" `elem` hcOptions GHC bi
      filterHcOptions p hcoptss =
        [ (hc, if hc == GHC then filter p opts else opts)
        | (hc, opts) <- hcoptss ]
  
  -- when using -split-objs, we need to search for object files in the
  -- Module_split directory for each module.
  getHaskellObjects :: Library -> LocalBuildInfo -> ComponentLocalBuildInfo
                    -> FilePath -> String -> Bool -> NoCallStackIO [FilePath]
  getHaskellObjects lib lbi clbi pref wanted_obj_ext allow_split_objs
    | splitObjs lbi && allow_split_objs = do
          let dirs = [ pref </> (ModuleName.toFilePath x ++ "_split")
                     | x <- allLibModules lib clbi ]
          objss <- traverse getDirectoryContents dirs
          let objs = [ dir </> obj
                     | (objs',dir) <- zip objss dirs, obj <- objs',
                       let obj_ext = takeExtension obj,
                       '.':wanted_obj_ext == obj_ext ]
          return objs
    | otherwise  =
          return [ pref </> ModuleName.toFilePath x <.> wanted_obj_ext
                 | x <- allLibModules lib clbi ]
  
  
  constructGHCCmdLine
          :: LocalBuildInfo
          -> BuildInfo
          -> ComponentLocalBuildInfo
          -> FilePath
          -> Verbosity
          -> [String]
  constructGHCCmdLine lbi bi clbi odir verbosity =
          ["--make"]
       ++ ghcVerbosityOptions verbosity
          -- Unsupported extensions have already been checked by configure
       ++ ghcOptions lbi bi clbi odir
  
  ghcVerbosityOptions :: Verbosity -> [String]
  ghcVerbosityOptions verbosity
       | verbosity >= deafening = ["-v"]
       | verbosity >= normal    = []
       | otherwise              = ["-w", "-v0"]
  
  ghcOptions :: LocalBuildInfo -> BuildInfo -> ComponentLocalBuildInfo
             -> FilePath -> [String]
  ghcOptions lbi bi clbi odir
       =  ["-hide-all-packages"]
       ++ ghcPackageDbOptions lbi
       ++ (if splitObjs lbi then ["-split-objs"] else [])
       ++ ["-i"]
       ++ ["-i" ++ odir]
       ++ ["-i" ++ l | l <- nub (hsSourceDirs bi)]
       ++ ["-i" ++ autogenComponentModulesDir lbi clbi]
       ++ ["-i" ++ autogenPackageModulesDir lbi]
       ++ ["-I" ++ autogenComponentModulesDir lbi clbi]
       ++ ["-I" ++ autogenPackageModulesDir lbi]
       ++ ["-I" ++ odir]
       ++ ["-I" ++ dir | dir <- PD.includeDirs bi]
       ++ ["-optP" ++ opt | opt <- cppOptions bi]
       ++ [ "-optP-include", "-optP"++ (autogenComponentModulesDir lbi clbi </> cppHeaderName) ]
       ++ [ "-#include \"" ++ inc ++ "\"" | inc <- PD.includes bi ]
       ++ [ "-odir",  odir, "-hidir", odir ]
       ++ (if compilerVersion c >= mkVersion [6,8]
             then ["-stubdir", odir] else [])
       ++ ghcPackageFlags lbi clbi
       ++ (case withOptimization lbi of
             NoOptimisation      -> []
             NormalOptimisation  -> ["-O"]
             MaximumOptimisation -> ["-O2"])
       ++ hcOptions GHC bi
       ++ languageToFlags c (defaultLanguage bi)
       ++ extensionsToFlags c (usedExtensions bi)
      where c = compiler lbi
  
  ghcPackageFlags :: LocalBuildInfo -> ComponentLocalBuildInfo -> [String]
  ghcPackageFlags lbi clbi
    | ghcVer >= mkVersion [6,11]
                = concat [ ["-package-id", display ipkgid]
                         | (ipkgid, _) <- componentPackageDeps clbi ]
  
    | otherwise = concat [ ["-package", display pkgid]
                         | (_, pkgid)  <- componentPackageDeps clbi ]
      where
        ghcVer = compilerVersion (compiler lbi)
  
  ghcPackageDbOptions :: LocalBuildInfo -> [String]
  ghcPackageDbOptions lbi = case dbstack of
    (GlobalPackageDB:UserPackageDB:dbs) -> concatMap specific dbs
    (GlobalPackageDB:dbs)               -> ("-no-user-" ++ packageDbFlag)
                                         : concatMap specific dbs
    _                                   -> ierror
   where
      specific (SpecificPackageDB db) = [ '-':packageDbFlag, db ]
      specific _ = ierror
      ierror     = error ("internal error: unexpected package db stack: " ++ show dbstack)
  
      dbstack = withPackageDB lbi
      packageDbFlag
        | compilerVersion (compiler lbi) < mkVersion [7,5]
        = "package-conf"
        | otherwise
        = "package-db"
  
  constructCcCmdLine :: LocalBuildInfo -> BuildInfo -> ComponentLocalBuildInfo
                     -> FilePath -> FilePath -> Verbosity -> (FilePath,[String])
  constructCcCmdLine lbi bi clbi pref filename verbosity
    =  let odir | compilerVersion (compiler lbi) >= mkVersion [6,4,1] = pref
                | otherwise = pref </> takeDirectory filename
                          -- ghc 6.4.1 fixed a bug in -odir handling
                          -- for C compilations.
       in
          (odir,
           ghcCcOptions lbi bi clbi odir
           ++ (if verbosity >= deafening then ["-v"] else [])
           ++ ["-c",filename])
  
  
  ghcCcOptions :: LocalBuildInfo -> BuildInfo -> ComponentLocalBuildInfo
               -> FilePath -> [String]
  ghcCcOptions lbi bi clbi odir
       =  ["-I" ++ dir | dir <- PD.includeDirs bi]
       ++ ghcPackageDbOptions lbi
       ++ ghcPackageFlags lbi clbi
       ++ ["-optc" ++ opt | opt <- PD.ccOptions bi]
       ++ (case withOptimization lbi of
             NoOptimisation -> []
             _              -> ["-optc-O2"])
       ++ ["-odir", odir]
  
  mkGHCiLibName :: UnitId -> String
  mkGHCiLibName lib = getHSLibraryName lib <.> "o"
  
  -- -----------------------------------------------------------------------------
  -- Installing
  
  -- |Install executables for GHC.
  installExe :: Verbosity
             -> LocalBuildInfo
             -> InstallDirs FilePath -- ^Where to copy the files to
             -> FilePath  -- ^Build location
             -> (FilePath, FilePath)  -- ^Executable (prefix,suffix)
             -> PackageDescription
             -> Executable
             -> IO ()
  installExe verbosity lbi installDirs buildPref (progprefix, progsuffix) _pkg exe = do
    let binDir = bindir installDirs
    createDirectoryIfMissingVerbose verbosity True binDir
    let exeFileName = unUnqualComponentName (exeName exe) <.> exeExtension
        fixedExeBaseName = progprefix ++ unUnqualComponentName (exeName exe) ++ progsuffix
        installBinary dest = do
            installExecutableFile verbosity
              (buildPref </> unUnqualComponentName (exeName exe) </> exeFileName)
              (dest <.> exeExtension)
            stripExe verbosity lbi exeFileName (dest <.> exeExtension)
    installBinary (binDir </> fixedExeBaseName)
  
  stripExe :: Verbosity -> LocalBuildInfo -> FilePath -> FilePath -> IO ()
  stripExe verbosity lbi name path = when (stripExes lbi) $
    case lookupProgram stripProgram (withPrograms lbi) of
      Just strip -> runProgram verbosity strip args
      Nothing    -> unless (buildOS == Windows) $
                    -- Don't bother warning on windows, we don't expect them to
                    -- have the strip program anyway.
                    warn verbosity $ "Unable to strip executable '" ++ name
                                  ++ "' (missing the 'strip' program)"
    where
      args = path : case buildOS of
         OSX -> ["-x"] -- By default, stripping the ghc binary on at least
                       -- some OS X installations causes:
                       --     HSbase-3.0.o: unknown symbol `_environ'"
                       -- The -x flag fixes that.
         _   -> []
  
  -- |Install for ghc, .hi, .a and, if --with-ghci given, .o
  installLib    :: Verbosity
                -> LocalBuildInfo
                -> FilePath  -- ^install location
                -> FilePath  -- ^install location for dynamic libraries
                -> FilePath  -- ^Build location
                -> PackageDescription
                -> Library
                -> ComponentLocalBuildInfo
                -> IO ()
  installLib verbosity lbi targetDir dynlibTargetDir builtDir _pkg lib clbi = do
    -- copy .hi files over:
    let copy src dst n = do
          createDirectoryIfMissingVerbose verbosity True dst
          installOrdinaryFile verbosity (src </> n) (dst </> n)
        copyModuleFiles ext =
          findModuleFiles [builtDir] [ext] (allLibModules lib clbi)
            >>= installOrdinaryFiles verbosity targetDir
    ifVanilla $ copyModuleFiles "hi"
    ifProf    $ copyModuleFiles "p_hi"
    hcrFiles <- findModuleFiles (builtDir : hsSourceDirs (libBuildInfo lib)) ["hcr"] (allLibModules lib clbi)
    flip traverse_ hcrFiles $ \(srcBase, srcFile) -> runLhc ["--install-library", srcBase </> srcFile]
  
    -- copy the built library files over:
    ifVanilla $ copy builtDir targetDir       vanillaLibName
    ifProf    $ copy builtDir targetDir       profileLibName
    ifGHCi    $ copy builtDir targetDir       ghciLibName
    ifShared  $ copy builtDir dynlibTargetDir sharedLibName
  
    where
      cid = compilerId (compiler lbi)
      lib_name = componentUnitId clbi
      vanillaLibName = mkLibName           lib_name
      profileLibName = mkProfLibName       lib_name
      ghciLibName    = mkGHCiLibName       lib_name
      sharedLibName  = mkSharedLibName cid lib_name
  
      hasLib    = not $ null (allLibModules lib clbi)
                     && null (cSources (libBuildInfo lib))
      ifVanilla = when (hasLib && withVanillaLib lbi)
      ifProf    = when (hasLib && withProfLib    lbi)
      ifGHCi    = when (hasLib && withGHCiLib    lbi)
      ifShared  = when (hasLib && withSharedLib  lbi)
  
      runLhc    = runDbProgram verbosity lhcProgram (withPrograms lbi)
  
  -- -----------------------------------------------------------------------------
  -- Registering
  
  registerPackage
    :: Verbosity
    -> ProgramDb
    -> PackageDBStack
    -> InstalledPackageInfo
    -> HcPkg.RegisterOptions
    -> IO ()
  registerPackage verbosity progdb packageDbs installedPkgInfo registerOptions =
      HcPkg.register (hcPkgInfo progdb) verbosity packageDbs
                     installedPkgInfo registerOptions
  
  hcPkgInfo :: ProgramDb -> HcPkg.HcPkgInfo
  hcPkgInfo progdb = HcPkg.HcPkgInfo { HcPkg.hcPkgProgram    = lhcPkgProg
                                     , HcPkg.noPkgDbStack    = False
                                     , HcPkg.noVerboseFlag   = False
                                     , HcPkg.flagPackageConf = False
                                     , HcPkg.supportsDirDbs  = True
                                     , HcPkg.requiresDirDbs  = True
                                     , HcPkg.nativeMultiInstance  = False -- ?
                                     , HcPkg.recacheMultiInstance = False -- ?
                                     , HcPkg.suppressFilesCheck   = True
                                     }
    where
      Just lhcPkgProg = lookupProgram lhcPkgProgram progdb
  