    {-# OPTIONS -cpp #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.Simple.GHC
    -- Copyright   :  Isaac Jones 2003-2007
    --
    -- Maintainer  :  Isaac Jones <ijones@syntaxpolice.org>
    -- Stability   :  alpha
    -- Portability :  portable
    --
    -- Build and Install implementations for GHC.  See
    -- 'Distribution.Simple.GHC.PackageConfig.GHCPackageConfig' for
    -- registration-related stuff.

    {- Copyright (c) 2003-2005, Isaac Jones
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modiication, are permitted provided that the following conditions are
    met:

        * Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

        * Redistributions in binary form must reproduce the above
          copyright notice, this list of conditions and the following
          disclaimer in the documentation and/or other materials provided
          with the distribution.

        * Neither the name of Isaac Jones nor the names of other
          contributors may be used to endorse or promote products derived
          from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -}

    module Distribution.Simple.GHC (
            configure, getInstalledPackages, build, makefile, installLib, installExe,
            ghcVerbosityOptions
     ) where

    import Distribution.Simple.GHC.Makefile
    import Distribution.Simple.Setup       ( MakefileFlags(..) )
    import Distribution.PackageDescription
    				( PackageDescription(..), BuildInfo(..),
    				  withLib, setupMessage,
    				  Executable(..), withExe, Library(..),
    				  libModules, hcOptions )
    import Distribution.Simple.LocalBuildInfo
    				( LocalBuildInfo(..), autogenModulesDir )
    import Distribution.Simple.Utils
    import Distribution.Package  	( PackageIdentifier(..), showPackageId,
                                      parsePackageId )
    import Distribution.Simple.Program ( rawSystemProgram, rawSystemProgramConf,
    				  rawSystemProgramStdoutConf,
                                      rawSystemProgramStdout,
    				  Program(..), ConfiguredProgram(..),
                                      ProgramConfiguration,
                                      userMaybeSpecifyPath, requireProgram,
                                      programPath, lookupProgram, updateProgram,
                                      ghcProgram, ghcPkgProgram,
                                      arProgram, ranlibProgram, ldProgram )
    import Distribution.Simple.Compiler
    import Distribution.Version	( Version(..), showVersion,
                                      VersionRange(..), orLaterVersion )
    import qualified Distribution.Simple.GHC.PackageConfig as GHC
    				( localPackageConfig,
    				  canReadLocalPackageConfig )
    import Distribution.System
    import Distribution.Verbosity
    import Language.Haskell.Extension (Extension(..))
    import Distribution.Compat.ReadP
        ( readP_to_S, many, skipSpaces )

    import Control.Monad		( unless, when )
    import Data.Char
    import Data.List		( nub, isPrefixOf )
    import System.Directory		( removeFile, renameFile,
    				  getDirectoryContents, doesFileExist )
    import Distribution.Compat.Directory ( getTemporaryDirectory )
    import Distribution.Compat.TempFile ( withTempFile )
    import System.FilePath          ( (</>), (<.>), takeExtension,
                                      takeDirectory, replaceExtension, splitExtension )
    import System.IO
    import Control.Exception as Exception (handle)

    -- System.IO used to export a different try, so we can't use try unqualified
    #ifndef __NHC__
    import Control.Exception as Try
    #else
    import IO as Try
    #endif

    -- -----------------------------------------------------------------------------
    -- Configuring

    configure :: Verbosity -> Maybe FilePath -> Maybe FilePath
              -> ProgramConfiguration -> IO (Compiler, ProgramConfiguration)
    configure verbosity hcPath hcPkgPath conf = do

      (ghcProg, conf') <- requireProgram verbosity ghcProgram
                            (orLaterVersion (Version [6,2] []))
                            (userMaybeSpecifyPath "ghc" hcPath conf)
      let Just ghcVersion = programVersion ghcProg

      -- This is slightly tricky, we have to configure ghc first, then we use the
      -- location of ghc to help find ghc-pkg in the case that the user did not
      -- specify the location of ghc-pkg directly:
      (ghcPkgProg, conf'') <- requireProgram verbosity ghcPkgProgram {
                                programFindLocation = guessGhcPkgFromGhcPath ghcProg
                              }
                              (orLaterVersion (Version [0] []))
                              (userMaybeSpecifyPath "ghc-pkg" hcPkgPath conf')
      let Just ghcPkgVersion = programVersion ghcPkgProg

      when (ghcVersion /= ghcPkgVersion) $ die $
           "Version mismatch between ghc and ghc-pkg:\n"
        ++ programPath ghcProg ++ " is version " ++ showVersion ghcVersion ++ "\n"
        ++ programPath ghcPkgProg ++ " is version " ++ showVersion ghcPkgVersion

      -- finding ghc's local ld is a bit tricky as it's not on the path:
      let ldProgram' = case os of
            Windows _ ->
              let compilerDir  = takeDirectory (programPath ghcProg)
                  baseDir      = takeDirectory compilerDir
                  binInstallLd = baseDir </> "gcc-lib" </> "ld.exe"
               in ldProgram {
                      programFindLocation = \_ -> return (Just binInstallLd)
                    }
            _ -> ldProgram

      -- we need to find out if ld supports the -x flag
      (ldProg, conf''') <- requireProgram verbosity ldProgram' AnyVersion conf''
      tempDir <- getTemporaryDirectory
      ldx <- withTempFile tempDir "c" $ \testcfile ->
             withTempFile tempDir "o" $ \testofile -> do
               writeFile testcfile "int foo() {}\n"
               rawSystemProgram verbosity ghcProg ["-c", testcfile,
                                                   "-o", testofile]
               withTempFile tempDir "o" $ \testofile' ->
                 Exception.handle (\_ -> return False) $ do
                   rawSystemProgramStdout verbosity ldProg
                     ["-x", "-r", testofile, "-o", testofile']
                   return True
      let conf'''' = updateProgram ldProg {
                      programArgs = if ldx then ["-x"] else []
    		} conf'''
      -- Yeah yeah, so obviously conf''''' is totally rediculious and the program
      -- configuration needs to be in a state monad. That is exactly the plan
      -- (along with some other stuff to give Cabal a better DSL).

      let isSep c = isSpace c || (c == ',')
      languageExtensions <-
        if ghcVersion >= Version [6,7] []
          then do exts <- rawSystemStdout verbosity (programPath ghcProg)
                            ["--supported-languages"]
                  return [ (ext, "-X" ++ show ext)
                         | extStr <- breaks isSep exts
                         , (ext, "") <- reads extStr ++ reads ("No" ++ extStr) ]
          else return oldLanguageExtensions

      let comp = Compiler {
            compilerFlavor         = GHC,
            compilerId             = PackageIdentifier "ghc" ghcVersion,
            compilerExtensions     = languageExtensions
          }
      return (comp, conf'''')

    -- | Given something like /usr/local/bin/ghc-6.6.1(.exe) we try and find a
    -- corresponding ghc-pkg, we try looking for both a versioned and unversioned
    -- ghc-pkg in the same dir, that is:
    --
    -- > /usr/local/bin/ghc-pkg-6.6.1(.exe)
    -- > /usr/local/bin/ghc-pkg(.exe)
    --
    guessGhcPkgFromGhcPath :: ConfiguredProgram -> Verbosity -> IO (Maybe FilePath)
    guessGhcPkgFromGhcPath ghcProg verbosity
      = do let path            = programPath ghcProg
               dir             = takeDirectory path
               versionSuffix   = takeVersionSuffix (dropExeExtension path)
               guessNormal     = dir </> "ghc-pkg" <.> exeExtension
               guessVersioned  = dir </> ("ghc-pkg" ++ versionSuffix) <.> exeExtension
               guesses | null versionSuffix = [guessNormal]
                       | otherwise          = [guessVersioned, guessNormal]
           info verbosity $ "looking for package tool: ghc-pkg near compiler in " ++ dir
           exists <- mapM doesFileExist guesses
           case [ file | (file, True) <- zip guesses exists ] of
             [] -> return Nothing
             (pkgtool:_) -> do info verbosity $ "found package tool in " ++ pkgtool
                               return (Just pkgtool)

      where takeVersionSuffix :: FilePath -> String
            takeVersionSuffix = reverse . takeWhile (`elem ` "0123456789.-") . reverse

            dropExeExtension :: FilePath -> FilePath
            dropExeExtension filepath =
              case splitExtension filepath of
                (filepath', extension) | extension == exeExtension -> filepath'
                                       | otherwise                 -> filepath

    -- | For GHC 6.6.x and earlier, the mapping from supported extensions to flags
    oldLanguageExtensions :: [(Extension, Flag)]
    oldLanguageExtensions =
        [(OverlappingInstances       , "-fallow-overlapping-instances")
        ,(TypeSynonymInstances       , "-fglasgow-exts")
        ,(TemplateHaskell            , "-fth")
        ,(ForeignFunctionInterface   , "-fffi")
        ,(NoMonomorphismRestriction  , "-fno-monomorphism-restriction")
        ,(NoMonoPatBinds             , "-fno-mono-pat-binds")
        ,(UndecidableInstances       , "-fallow-undecidable-instances")
        ,(IncoherentInstances        , "-fallow-incoherent-instances")
        ,(Arrows                     , "-farrows")
        ,(Generics                   , "-fgenerics")
        ,(NoImplicitPrelude          , "-fno-implicit-prelude")
        ,(ImplicitParams             , "-fimplicit-params")
        ,(CPP                        , "-cpp")
        ,(BangPatterns               , "-fbang-patterns")
        ,(KindSignatures             , fglasgowExts)
        ,(RecursiveDo                , fglasgowExts)
        ,(ParallelListComp           , fglasgowExts)
        ,(MultiParamTypeClasses      , fglasgowExts)
        ,(FunctionalDependencies     , fglasgowExts)
        ,(Rank2Types                 , fglasgowExts)
        ,(RankNTypes                 , fglasgowExts)
        ,(PolymorphicComponents      , fglasgowExts)
        ,(ExistentialQuantification  , fglasgowExts)
        ,(ScopedTypeVariables        , "-fscoped-type-variables")
        ,(FlexibleContexts           , fglasgowExts)
        ,(FlexibleInstances          , fglasgowExts)
        ,(EmptyDataDecls             , fglasgowExts)
        ,(PatternGuards              , fglasgowExts)
        ,(GeneralizedNewtypeDeriving , fglasgowExts)
        ,(MagicHash                  , fglasgowExts)
        ,(UnicodeSyntax              , fglasgowExts)
        ,(PatternSignatures          , fglasgowExts)
        ,(UnliftedFFITypes           , fglasgowExts)
        ,(LiberalTypeSynonyms        , fglasgowExts)
        ,(TypeOperators              , fglasgowExts)
        ,(GADTs                      , fglasgowExts)
        ,(RelaxedPolyRec             , fglasgowExts)
        ,(ExtendedDefaultRules       , "-fextended-default-rules")
        ,(UnboxedTuples              , fglasgowExts)
        ,(DeriveDataTypeable         , fglasgowExts)
        ,(ConstrainedClassMethods    , fglasgowExts)
        ]
        where
          fglasgowExts = "-fglasgow-exts"

    getInstalledPackages :: Verbosity -> PackageDB -> ProgramConfiguration
                         -> IO [PackageIdentifier]
    getInstalledPackages verbosity packagedb conf = do
       --TODO: use --simple-output flag for easier parsing
       str <- rawSystemProgramStdoutConf verbosity ghcPkgProgram conf
                [packageDbGhcPkgFlag packagedb, "list"]
       let str1 = case packagedb of
                    UserPackageDB -> allFiles str
                    _             -> firstFile str
           str2 = filter (`notElem` ",(){}") str1
           --
       case pCheck (readP_to_S (many (skipSpaces >> parsePackageId)) str2) of
         [ps] -> return ps
         _    -> die "cannot parse package list"
      where
        packageDbGhcPkgFlag GlobalPackageDB          = "--global"
        packageDbGhcPkgFlag UserPackageDB            = "--user"
        packageDbGhcPkgFlag (SpecificPackageDB path) = "--package-conf=" ++ path

        pCheck :: [(a, [Char])] -> [a]
        pCheck rs = [ r | (r,s) <- rs, all isSpace s ]

        allFiles str = unlines $ filter keep_line $ lines str
            where keep_line s = ':' `notElem` s && not ("Creating" `isPrefixOf` s)

        firstFile str = unlines $ takeWhile (not . file_line) $
                        drop 1 $ dropWhile (not . file_line) $ lines str
            where file_line s = ':' `elem` s && not ("Creating" `isPrefixOf` s)

    -- -----------------------------------------------------------------------------
    -- Building

    -- |Building for GHC.  If .ghc-packages exists and is readable, add
    -- it to the command-line.
    build :: PackageDescription -> LocalBuildInfo -> Verbosity -> IO ()
    build pkg_descr lbi verbosity = do
      let pref = buildDir lbi
          runGhcProg = rawSystemProgramConf verbosity ghcProgram (withPrograms lbi)
          ifVanillaLib forceVanilla = when (forceVanilla || withVanillaLib lbi)
          ifProfLib = when (withProfLib lbi)
          ifSharedLib = when (withSharedLib lbi)
          ifGHCiLib = when (withGHCiLib lbi)

      -- GHC versions prior to 6.4 didn't have the user package database,
      -- so we fake it.  TODO: This can go away in due course.
      pkg_conf <- if versionBranch (compilerVersion (compiler lbi)) >= [6,4]
    		then return []
    		else do  pkgConf <- GHC.localPackageConfig
    			 pkgConfReadable <- GHC.canReadLocalPackageConfig
    			 if pkgConfReadable
    				then return ["-package-conf", pkgConf]
    				else return []

      -- Build lib
      withLib pkg_descr () $ \lib -> do
          info verbosity "Building library..."
          let libBi = libBuildInfo lib
              libTargetDir = pref
    	  forceVanillaLib = TemplateHaskell `elem` extensions libBi
    	  -- TH always needs vanilla libs, even when building for profiling

          createDirectoryIfMissingVerbose verbosity True libTargetDir
          -- put hi-boot files into place for mutually recurive modules
          smartCopySources verbosity (hsSourceDirs libBi)
                           libTargetDir (libModules pkg_descr) ["hi-boot"] False False
          let ghc_vers = compilerVersion (compiler lbi)
              packageId | versionBranch ghc_vers >= [6,4]
                                    = showPackageId (package pkg_descr)
                        | otherwise = pkgName (package pkg_descr)
              -- Only use the version number with ghc-6.4 and later
              ghcArgs =
                     pkg_conf
                  ++ ["-package-name", packageId ]
                  ++ constructGHCCmdLine lbi libBi libTargetDir verbosity
                  ++ (libModules pkg_descr)
              ghcArgsProf = ghcArgs
                  ++ ["-prof",
                      "-hisuf", "p_hi",
                      "-osuf", "p_o"
                     ]
                  ++ ghcProfOptions libBi
              ghcArgsShared = ghcArgs
                  ++ ["-dynamic",
                      "-hisuf", "dyn_hi",
                      "-osuf", "dyn_o", "-fPIC"
                     ]
                  ++ ghcSharedOptions libBi
          unless (null (libModules pkg_descr)) $
            do ifVanillaLib forceVanillaLib (runGhcProg ghcArgs)
               ifProfLib (runGhcProg ghcArgsProf)
               ifSharedLib (runGhcProg ghcArgsShared)

          -- build any C sources
          unless (null (cSources libBi)) $ do
             info verbosity "Building C Sources..."
             sequence_ [do let (odir,args) = constructCcCmdLine lbi libBi 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)
    	  libName  = mkLibName pref (showPackageId (package pkg_descr))
    	  profLibName  = mkProfLibName pref (showPackageId (package pkg_descr))
    	  sharedLibName  = mkSharedLibName pref (showPackageId (package pkg_descr)) (compilerId (compiler lbi))
    	  ghciLibName = mkGHCiLibName pref (showPackageId (package pkg_descr))

          stubObjs <- sequence [moduleToFilePath [libTargetDir] (x ++"_stub") [objExtension]
                               |  x <- libModules pkg_descr ]  >>= return . concat
          stubProfObjs <- sequence [moduleToFilePath [libTargetDir] (x ++"_stub") ["p_" ++ objExtension]
                               |  x <- libModules pkg_descr ]  >>= return . concat
          stubSharedObjs <- sequence [moduleToFilePath [libTargetDir] (x ++"_stub") ["dyn_" ++ objExtension]
                               |  x <- libModules pkg_descr ]  >>= return . concat

          hObjs     <- getHaskellObjects pkg_descr libBi lbi
    			pref objExtension True
          hProfObjs <-
    	if (withProfLib lbi)
    		then getHaskellObjects pkg_descr libBi lbi
    			pref ("p_" ++ objExtension) True
    		else return []
          hSharedObjs <-
    	if (withSharedLib lbi)
    		then getHaskellObjects pkg_descr libBi lbi
    			pref ("dyn_" ++ objExtension) False
    		else return []

          unless (null hObjs && null cObjs && null stubObjs) $ do
            Try.try (removeFile libName) -- first remove library if it exists
            Try.try (removeFile profLibName) -- first remove library if it exists
            Try.try (removeFile sharedLibName) -- first remove library if it exists
    	Try.try (removeFile ghciLibName) -- first remove library if it exists

            let arVerbosity | verbosity >= deafening = "v"
                            | verbosity >= normal = ""
                            | otherwise = "c"
                arArgs = ["q"++ arVerbosity]
                    ++ [libName]
                arObjArgs =
    		   hObjs
                    ++ map (pref </>) cObjs
                    ++ stubObjs
                arProfArgs = ["q"++ arVerbosity]
                    ++ [profLibName]
                arProfObjArgs =
    		   hProfObjs
                    ++ map (pref </>) cObjs
                    ++ stubProfObjs
    	    ldArgs = ["-r"]
    	        ++ ["-o", ghciLibName <.> "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 =
    		[ "-shared",
    		  "-dynamic",
    		  "-o", sharedLibName ]
    		++ ghcSharedObjArgs
    		++ ["-package-name", packageId ]
    		++ (concat [ ["-package", showPackageId pkg] | pkg <- packageDeps lbi ])
    	        ++ ["-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 on unix
                -- used to be 30k, but Solaris needs 2k (see GHC bug #1785)
                maxCommandLineSize = 2048

            ifVanillaLib False $ xargs maxCommandLineSize
              runAr arArgs arObjArgs

            ifProfLib $ xargs maxCommandLineSize
              runAr arProfArgs arProfObjArgs

            ifGHCiLib $ xargs maxCommandLineSize
              (runLd ghciLibName) ldArgs ldObjArgs

            ifSharedLib $ runGhcProg ghcSharedLinkArgs

      -- build any executables
      withExe pkg_descr $ \ (Executable exeName' modPath exeBi) -> do
                     info verbosity $ "Building executable: " ++ exeName' ++ "..."

                     -- 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
                     -- put hi-boot files into place for mutually recursive modules
                     -- FIX: what about exeName.hi-boot?
                     smartCopySources verbosity (hsSourceDirs exeBi)
                                      exeDir (otherModules exeBi) ["hi-boot"] False False

                     -- build executables
                     unless (null (cSources exeBi)) $ do
                      info verbosity "Building C Sources."
    		  sequence_ [do let (odir,args) = constructCcCmdLine lbi exeBi
                                                             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 binArgs linkExe profExe =
                                pkg_conf
    			 ++ (if linkExe
    			        then ["-o", targetDir </> exeNameReal]
                                    else ["-c"])
                             ++ constructGHCCmdLine lbi exeBi exeDir verbosity
                             ++ [exeDir </> x | x <- cObjs]
                             ++ [srcMainFile]
    			 ++ ldOptions exeBi
    			 ++ ["-l"++lib | lib <- extraLibs exeBi]
    			 ++ ["-L"++libDir | libDir <- extraLibDirs exeBi]
                             ++ if profExe
                                   then ["-prof",
                                         "-hisuf", "p_hi",
                                         "-osuf", "p_o"
                                        ] ++ ghcProfOptions 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 && TemplateHaskell `elem` extensions exeBi)
    		    (runGhcProg (binArgs False False))

    		 runGhcProg (binArgs True (withProfExe lbi))

    -- when using -split-objs, we need to search for object files in the
    -- Module_split directory for each module.
    getHaskellObjects :: PackageDescription -> BuildInfo -> LocalBuildInfo
     	-> FilePath -> String -> Bool -> IO [FilePath]
    getHaskellObjects pkg_descr _ lbi pref wanted_obj_ext allow_split_objs
      | splitObjs lbi && allow_split_objs = do
    	let dirs = [ pref </> (dotToSep x ++ "_split")
    		   | x <- libModules pkg_descr ]
    	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 </> dotToSep x <.> wanted_obj_ext
                   | x <- libModules pkg_descr ]

    constructGHCCmdLine
            :: LocalBuildInfo
            -> BuildInfo
            -> FilePath
            -> Verbosity
            -> [String]
    constructGHCCmdLine lbi bi odir verbosity =
            ["--make"]
         ++ ghcVerbosityOptions verbosity
            -- Unsupported extensions have already been checked by configure
         ++ ghcOptions lbi bi odir

    ghcVerbosityOptions :: Verbosity -> [String]
    ghcVerbosityOptions verbosity
         | verbosity >= deafening = ["-v"]
         | verbosity >= normal    = []
         | otherwise              = ["-w", "-v0"]

    ghcOptions :: LocalBuildInfo -> BuildInfo -> FilePath -> [String]
    ghcOptions lbi bi odir
         =  (if compilerVersion c > Version [6,4] []
                then ["-hide-all-packages"]
                else [])
         ++ (if splitObjs lbi then ["-split-objs"] else [])
         ++ ["-i"]
         ++ ["-i" ++ autogenModulesDir lbi]
         ++ ["-i" ++ odir]
         ++ ["-i" ++ l | l <- nub (hsSourceDirs bi)]
         ++ ["-I" ++ odir]
         ++ ["-I" ++ dir | dir <- includeDirs bi]
         ++ ["-optP" ++ opt | opt <- cppOptions bi]
         ++ ["-optc" ++ opt | opt <- ccOptions bi]
         ++ [ "-#include \"" ++ inc ++ "\"" | inc <- includes bi ]
         ++ [ "-odir",  odir, "-hidir", odir ]
         ++ (if compilerVersion c >= Version [6,8] []
               then ["-stubdir", odir] else [])
         ++ (concat [ ["-package", showPackageId pkg] | pkg <- packageDeps lbi ])
         ++ (if withOptimization lbi then ["-O"] else [])
         ++ hcOptions GHC (options bi)
         ++ extensionsToFlags c (extensions bi)
        where c = compiler lbi

    constructCcCmdLine :: LocalBuildInfo -> BuildInfo -> FilePath
                       -> FilePath -> Verbosity -> (FilePath,[String])
    constructCcCmdLine lbi bi 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 odir
             ++ (if verbosity > deafening then ["-v"] else [])
             ++ ["-c",filename])

    ghcCcOptions :: LocalBuildInfo -> BuildInfo -> FilePath -> [String]
    ghcCcOptions lbi bi odir
         =  ["-I" ++ dir | dir <- includeDirs bi]
         ++ concat [ ["-package", showPackageId pkg] | pkg <- packageDeps lbi ]
         ++ ["-optc" ++ opt | opt <- ccOptions bi]
         ++ (if withOptimization lbi then ["-optc-O2"] else [])
         ++ ["-odir", odir]

    mkGHCiLibName :: FilePath -- ^file Prefix
                  -> String   -- ^library name.
                  -> String
    mkGHCiLibName pref lib = pref </> ("HS" ++ lib) <.> ".o"

    -- -----------------------------------------------------------------------------
    -- Building a Makefile

    makefile :: PackageDescription -> LocalBuildInfo -> MakefileFlags -> IO ()
    makefile pkg_descr lbi flags = do
      let file = case makefileFile flags of
                    Just f ->  f
                    _otherwise -> "Makefile"
      targetExists <- doesFileExist file
      when targetExists $
        die ("Not overwriting existing copy of " ++ file)
      h <- openFile file WriteMode

      let Just lib = library pkg_descr
          bi = libBuildInfo lib

          ghc_vers = compilerVersion (compiler lbi)
          packageId | versionBranch ghc_vers >= [6,4]
                                    = showPackageId (package pkg_descr)
                     | otherwise = pkgName (package pkg_descr)
      (arProg, _) <- requireProgram (makefileVerbose flags) arProgram AnyVersion
                       (withPrograms lbi)
      (ldProg, _) <- requireProgram (makefileVerbose flags) ldProgram AnyVersion
                       (withPrograms lbi)
      let builddir = buildDir lbi
          Just ghcProg = lookupProgram ghcProgram (withPrograms lbi)
      let decls = [
            ("modules", unwords (exposedModules lib ++ otherModules bi)),
            ("GHC", programPath ghcProg),
            ("GHC_VERSION", (showVersion (compilerVersion (compiler lbi)))),
            ("WAYS", (if withProfLib lbi then "p " else "") ++ (if withSharedLib lbi then "dyn" else "")),
            ("odir", builddir),
            ("srcdir", case hsSourceDirs bi of
                            [one] -> one
                            _     -> error "makefile: can't cope with multiple hs-source-dirs yet, sorry"),
            ("package", packageId),
            ("GHC_OPTS", unwords (
                               ["-package-name", packageId ]
                            ++ ghcOptions lbi bi (buildDir lbi))),
            ("MAKEFILE", file),
            ("C_SRCS", unwords (cSources bi)),
            ("GHC_CC_OPTS", unwords (ghcCcOptions lbi bi (buildDir lbi))),
            ("GHCI_LIB", mkGHCiLibName builddir (showPackageId (package pkg_descr))),
            ("soext", dllExtension),
            ("LIB_LD_OPTS", unwords (["-package-name", packageId]
    				 ++ concat [ ["-package", showPackageId pkg] | pkg <- packageDeps lbi ]
    				 ++ ["-l"++libName | libName <- extraLibs bi]
    				 ++ ["-L"++libDir | libDir <- extraLibDirs bi])),
            ("AR", programPath arProg),
            ("LD", programPath ldProg ++ concat [" " ++ arg | arg <- programArgs ldProg ])
            ]
      hPutStrLn h "# DO NOT EDIT!  Automatically generated by Cabal\n"
      hPutStrLn h (unlines (map (\(a,b)-> a ++ " = " ++ munge b) decls))
      hPutStrLn h makefileTemplate
      hClose h
     where
      munge "" = ""
      munge ('#':s) = '\\':'#':munge s
      munge ('\\':s) = '/':munge s
    	-- for Windows, we want to use forward slashes in our pathnames in the Makefile
      munge (c:s) = c : munge s

    -- -----------------------------------------------------------------------------
    -- Installing

    -- |Install executables for GHC.
    installExe :: Verbosity -- ^verbosity
               -> FilePath  -- ^install location
               -> FilePath  -- ^Build location
               -> PackageDescription
               -> IO ()
    installExe verbosity pref buildPref pkg_descr
        = do createDirectoryIfMissingVerbose verbosity True pref
             withExe pkg_descr $ \ (Executable e _ _) -> do
                 let exeFileName = e <.> exeExtension
                 copyFileVerbose verbosity (buildPref </> e </> exeFileName) (pref </> exeFileName)

    -- |Install for ghc, .hi, .a and, if --with-ghci given, .o
    installLib    :: Verbosity -- ^verbosity
                  -> LocalBuildInfo
                  -> FilePath  -- ^install location
                  -> FilePath  -- ^install location for dynamic librarys
                  -> FilePath  -- ^Build location
                  -> PackageDescription -> IO ()
    installLib verbosity lbi pref dynPref buildPref
                  pd@PackageDescription{library=Just _,
                                        package=p}
        = do let programConf = withPrograms lbi
             ifVanilla $ smartCopySources verbosity [buildPref] pref (libModules pd) ["hi"] True False
             ifProf $ smartCopySources verbosity [buildPref] pref (libModules pd) ["p_hi"] True False
             let libTargetLoc = mkLibName pref (showPackageId p)
                 profLibTargetLoc = mkProfLibName pref (showPackageId p)
    	     libGHCiTargetLoc = mkGHCiLibName pref (showPackageId p)
    	     sharedLibTargetLoc = mkSharedLibName dynPref (showPackageId p) (compilerId (compiler lbi))
             ifVanilla $ copyFileVerbose verbosity (mkLibName buildPref (showPackageId p)) libTargetLoc
             ifProf $ copyFileVerbose verbosity (mkProfLibName buildPref (showPackageId p)) profLibTargetLoc
    	 ifGHCi $ copyFileVerbose verbosity (mkGHCiLibName buildPref (showPackageId p)) libGHCiTargetLoc
    	 ifShared $ copyFileVerbose verbosity (mkSharedLibName buildPref (showPackageId p) (compilerId (compiler lbi))) sharedLibTargetLoc

             -- use ranlib or ar -s to build an index. this is necessary
             -- on some systems like MacOS X.  If we can't find those,
             -- don't worry too much about it.
             case lookupProgram ranlibProgram programConf of
               Just rl  -> do ifVanilla $ rawSystemProgram verbosity rl [libTargetLoc]
                              ifProf $ rawSystemProgram verbosity rl [profLibTargetLoc]

               Nothing -> case lookupProgram arProgram programConf of
                              Just ar  -> do ifVanilla $ rawSystemProgram verbosity ar ["-s", libTargetLoc]
                                             ifProf $ rawSystemProgram verbosity ar ["-s", profLibTargetLoc]
                              Nothing -> setupMessage verbosity "Warning: Unable to generate index for library (missing ranlib and ar)" pd
             return ()
        where ifVanilla action = when (withVanillaLib lbi) (action >> return ())
              ifProf action = when (withProfLib lbi) (action >> return ())
              ifGHCi action = when (withGHCiLib lbi) (action >> return ())
              ifShared action = when (withSharedLib lbi) (action >> return ())

    installLib _ _ _ _ _ PackageDescription{library=Nothing}
        = die $ "Internal Error. installLibGHC called with no library."