    -----------------------------------------------------------------------------
    -- |
    -- 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 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 Control.Monad            ( unless, when )
    import Data.Monoid as Mon
    import Data.List
    import qualified Data.Map as M  ( empty )
    import Data.Maybe               ( catMaybes )
    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
              -> ProgramConfiguration -> IO (Compiler, Maybe Platform, ProgramConfiguration)
    configure verbosity hcPath hcPkgPath conf = do

      (lhcProg, lhcVersion, conf') <-
        requireProgramVersion verbosity lhcProgram
          (orLaterVersion (Version [0,7] []))
          (userMaybeSpecifyPath "lhc" hcPath conf)

      (lhcPkgProg, lhcPkgVersion, conf'') <-
        requireProgramVersion verbosity lhcPkgProgram
          (orLaterVersion (Version [0,7] []))
          (userMaybeSpecifyPath "lhc-pkg" hcPkgPath conf')

      when (lhcVersion /= lhcPkgVersion) $ die $
           "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     = M.empty
          }
          conf''' = configureToolchain lhcProg conf'' -- configure gcc and ld
          compPlatform = Nothing
      return (comp, compPlatform, conf''')

    -- | Adjust the way we find and configure gcc and ld
    --
    configureToolchain :: ConfiguredProgram -> ProgramConfiguration
                                            -> ProgramConfiguration
    configureToolchain lhcProg =
        addKnownProgram gccProgram {
          programFindLocation = findProg gccProgram (baseDir </> "gcc.exe"),
          programPostConf     = configureGcc
        }
      . addKnownProgram ldProgram {
          programFindLocation = findProg ldProgram (libDir </> "ld.exe"),
          programPostConf     = configureLd
        }
      where
        compilerDir = takeDirectory (programPath lhcProg)
        baseDir     = takeDirectory compilerDir
        libDir      = 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 -> IO 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" ++ libDir,
                                                          "-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
                   rawSystemProgram verbosity lhcProg ["-c", testcfile,
                                                       "-o", testofile]
                   withTempFile tempDir ".o" $ \testofile' testohnd' ->
                     do
                       hClose testohnd'
                       _ <- rawSystemProgramStdout 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 -> IO [(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 -> ProgramConfiguration
                         -> IO InstalledPackageIndex
    getInstalledPackages verbosity packagedbs conf = do
      checkPackageDbStack packagedbs
      pkgss <- getInstalledPackages' lhcPkg verbosity packagedbs conf
      let indexes = [ PackageIndex.fromList (map (substTopDir topDir) pkgs)
                    | (_, pkgs) <- pkgss ]
      return $! (Mon.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 conf
        Just lhcPkg  = lookupProgram lhcPkgProgram conf
        compilerDir  = takeDirectory (programPath ghcProg)
        topDir       = takeDirectory compilerDir

    checkPackageDbStack :: PackageDBStack -> IO ()
    checkPackageDbStack (GlobalPackageDB:rest)
      | GlobalPackageDB `notElem` rest = return ()
    checkPackageDbStack _ =
      die $ "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] -> ProgramConfiguration
                          -> IO [(PackageDB, [InstalledPackageInfo])]
    getInstalledPackages' lhcPkg verbosity packagedbs conf
      =
      sequence
        [ do str <- rawSystemProgramStdoutConf verbosity lhcPkgProgram conf
                      ["dump", packageDbGhcPkgFlag packagedb]
               `catchExit` \_ -> die $ "ghc-pkg dump failed"
             case parsePackages str of
               Left ok -> return (packagedb, ok)
               _       -> die "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 (Version [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 libName = componentUnitId clbi
          pref = buildDir lbi
          pkgid = packageId pkg_descr
          runGhcProg = rawSystemProgramConf 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 (libModules lib)
          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 (libModules lib)) $
        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           libName
          profileLibFilePath = libTargetDir </> mkProfLibName       libName
          sharedLibFilePath  = libTargetDir </> mkSharedLibName cid libName
          ghciLibFilePath    = libTargetDir </> mkGHCiLibName       libName

      stubObjs <- fmap catMaybes $ sequence
        [ findFileWithExtension [objExtension] [libTargetDir]
            (ModuleName.toFilePath x ++"_stub")
        | x <- libModules lib ]
      stubProfObjs <- fmap catMaybes $ sequence
        [ findFileWithExtension ["p_" ++ objExtension] [libTargetDir]
            (ModuleName.toFilePath x ++"_stub")
        | x <- libModules lib ]
      stubSharedObjs <- fmap catMaybes $ sequence
        [ findFileWithExtension ["dyn_" ++ objExtension] [libTargetDir]
            (ModuleName.toFilePath x ++"_stub")
        | x <- libModules lib ]

      hObjs     <- getHaskellObjects lib lbi
                        pref objExtension True
      hProfObjs <-
        if (withProfLib lbi)
                then getHaskellObjects lib lbi
                        pref ("p_" ++ objExtension) True
                else return []
      hSharedObjs <-
        if (withSharedLib lbi)
                then getHaskellObjects lib lbi
                        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 <libName>.
              rawSystemProgramConf verbosity ldProgram (withPrograms lbi)
                (args ++ if exists then [ldLibName] else [])
              renameFile (ldLibName <.> "tmp") ldLibName

            runAr = rawSystemProgramConf 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 pref = buildDir lbi
          runGhcProg = rawSystemProgramConf 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"++libDir | libDir <- 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 < Version [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
                      -> FilePath -> String -> Bool -> IO [FilePath]
    getHaskellObjects lib lbi pref wanted_obj_ext allow_split_objs
      | splitObjs lbi && allow_split_objs = do
            let dirs = [ pref </> (ModuleName.toFilePath x ++ "_split")
                       | x <- libModules lib ]
            objss <- mapM 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 <- libModules lib ]

    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" ++ autogenModulesDir lbi]
         ++ ["-I" ++ autogenModulesDir lbi]
         ++ ["-I" ++ odir]
         ++ ["-I" ++ dir | dir <- PD.includeDirs bi]
         ++ ["-optP" ++ opt | opt <- cppOptions bi]
         ++ [ "-optP-include", "-optP"++ (autogenModulesDir lbi </> cppHeaderName) ]
         ++ [ "-#include \"" ++ inc ++ "\"" | inc <- PD.includes bi ]
         ++ [ "-odir",  odir, "-hidir", odir ]
         ++ (if compilerVersion c >= Version [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 >= Version [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) < Version [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) >= Version [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 = exeName exe <.> exeExtension
          fixedExeBaseName = progprefix ++ exeName exe ++ progsuffix
          installBinary dest = do
              installExecutableFile verbosity
                (buildPref </> 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 -> rawSystemProgram 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] (libModules lib)
              >>= installOrdinaryFiles verbosity targetDir
      ifVanilla $ copyModuleFiles "hi"
      ifProf    $ copyModuleFiles "p_hi"
      hcrFiles <- findModuleFiles (builtDir : hsSourceDirs (libBuildInfo lib)) ["hcr"] (libModules lib)
      flip mapM_ 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)
        libName = componentUnitId clbi
        vanillaLibName = mkLibName           libName
        profileLibName = mkProfLibName       libName
        ghciLibName    = mkGHCiLibName       libName
        sharedLibName  = mkSharedLibName cid libName

        hasLib    = not $ null (libModules lib)
                       && 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    = rawSystemProgramConf verbosity lhcProgram (withPrograms lbi)

    -- -----------------------------------------------------------------------------
    -- Registering

    registerPackage
      :: Verbosity
      -> ProgramConfiguration
      -> PackageDBStack
      -> InstalledPackageInfo
      -> IO ()
    registerPackage verbosity progdb packageDbs installedPkgInfo =
      HcPkg.reregister (hcPkgInfo progdb) verbosity packageDbs
        (Right installedPkgInfo)

    hcPkgInfo :: ProgramConfiguration -> HcPkg.HcPkgInfo
    hcPkgInfo conf = 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 -- ?
                                     }
      where
        Just lhcPkgProg = lookupProgram lhcPkgProgram conf