/ghc-7.0.4/compiler/main/Packages.lhs

%
% (c) The University of Glasgow, 2006
%
\begin{code}
-- | Package manipulation
module Packages (
	module PackageConfig,

	-- * The PackageConfigMap
	PackageConfigMap, emptyPackageConfigMap, lookupPackage,
	extendPackageConfigMap,	dumpPackages,

	-- * Reading the package config, and processing cmdline args
	PackageState(..),
	initPackages,
	getPackageDetails,
	lookupModuleInAllPackages,

	-- * Inspecting the set of packages in scope
	getPackageIncludePath,
	getPackageLibraryPath,
	getPackageLinkOpts,
	getPackageExtraCcOpts,
	getPackageFrameworkPath,
	getPackageFrameworks,
	getPreloadPackagesAnd,

        collectIncludeDirs, collectLibraryPaths, collectLinkOpts,
        packageHsLibs,

	-- * Utils
	isDllName
    )
where

#include "HsVersions.h"

import PackageConfig	
import DynFlags		( dopt, DynFlag(..), DynFlags(..), PackageFlag(..) )
import StaticFlags
import Config		( cProjectVersion )
import Name		( Name, nameModule_maybe )
import UniqFM
import Module
import Util
import Panic
import Outputable
import Maybes

import System.Environment ( getEnv )
import Distribution.InstalledPackageInfo
import Distribution.InstalledPackageInfo.Binary
import Distribution.Package hiding (PackageId,depends)
import FastString
import ErrUtils         ( debugTraceMsg, putMsg, Message )
import Exception

import System.Directory
import System.FilePath
import Control.Monad
import Data.List as List
import Data.Map (Map)
import qualified Data.Map as Map
import qualified FiniteMap as Map
import qualified Data.Set as Set

-- ---------------------------------------------------------------------------
-- The Package state

-- | Package state is all stored in 'DynFlag's, including the details of
-- all packages, which packages are exposed, and which modules they
-- provide.
--
-- The package state is computed by 'initPackages', and kept in DynFlags.
--
--   * @-package <pkg>@ causes @<pkg>@ to become exposed, and all other packages 
--	with the same name to become hidden.
-- 
--   * @-hide-package <pkg>@ causes @<pkg>@ to become hidden.
-- 
--   * Let @exposedPackages@ be the set of packages thus exposed.  
--     Let @depExposedPackages@ be the transitive closure from @exposedPackages@ of
--     their dependencies.
--
--   * When searching for a module from an preload import declaration,
--     only the exposed modules in @exposedPackages@ are valid.
--
--   * When searching for a module from an implicit import, all modules
--     from @depExposedPackages@ are valid.
--
--   * When linking in a compilation manager mode, we link in packages the
--     program depends on (the compiler knows this list by the
--     time it gets to the link step).  Also, we link in all packages
--     which were mentioned with preload @-package@ flags on the command-line,
--     or are a transitive dependency of same, or are \"base\"\/\"rts\".
--     The reason for this is that we might need packages which don't
--     contain any Haskell modules, and therefore won't be discovered
--     by the normal mechanism of dependency tracking.

-- Notes on DLLs
-- ~~~~~~~~~~~~~
-- When compiling module A, which imports module B, we need to 
-- know whether B will be in the same DLL as A.  
-- 	If it's in the same DLL, we refer to B_f_closure
-- 	If it isn't, we refer to _imp__B_f_closure
-- When compiling A, we record in B's Module value whether it's
-- in a different DLL, by setting the DLL flag.

data PackageState = PackageState {
  pkgIdMap		:: PackageConfigMap, -- PackageId   -> PackageConfig
	-- The exposed flags are adjusted according to -package and
	-- -hide-package flags, and -ignore-package removes packages.

  preloadPackages      :: [PackageId],
	-- The packages we're going to link in eagerly.  This list
	-- should be in reverse dependency order; that is, a package
	-- is always mentioned before the packages it depends on.

  moduleToPkgConfAll 	:: UniqFM [(PackageConfig,Bool)], -- ModuleEnv mapping
	-- Derived from pkgIdMap.	
	-- Maps Module to (pkgconf,exposed), where pkgconf is the
	-- PackageConfig for the package containing the module, and
	-- exposed is True if the package exposes that module.

  installedPackageIdMap :: InstalledPackageIdMap
  }

-- | A PackageConfigMap maps a 'PackageId' to a 'PackageConfig'
type PackageConfigMap = UniqFM PackageConfig

type InstalledPackageIdMap = Map InstalledPackageId PackageId

type InstalledPackageIndex = Map InstalledPackageId PackageConfig

emptyPackageConfigMap :: PackageConfigMap
emptyPackageConfigMap = emptyUFM

-- | Find the package we know about with the given id (e.g. \"foo-1.0\"), if any
lookupPackage :: PackageConfigMap -> PackageId -> Maybe PackageConfig
lookupPackage = lookupUFM

extendPackageConfigMap
   :: PackageConfigMap -> [PackageConfig] -> PackageConfigMap
extendPackageConfigMap pkg_map new_pkgs 
  = foldl add pkg_map new_pkgs
  where add pkg_map p = addToUFM pkg_map (packageConfigId p) p

-- | Looks up the package with the given id in the package state, panicing if it is
-- not found
getPackageDetails :: PackageState -> PackageId -> PackageConfig
getPackageDetails ps pid = expectJust "getPackageDetails" (lookupPackage (pkgIdMap ps) pid)

-- ----------------------------------------------------------------------------
-- Loading the package config files and building up the package state

-- | Call this after 'DynFlags.parseDynFlags'.  It reads the package
-- configuration files, and sets up various internal tables of package
-- information, according to the package-related flags on the
-- command-line (@-package@, @-hide-package@ etc.)
--
-- Returns a list of packages to link in if we're doing dynamic linking.
-- This list contains the packages that the user explicitly mentioned with
-- @-package@ flags.
--
-- 'initPackages' can be called again subsequently after updating the
-- 'packageFlags' field of the 'DynFlags', and it will update the
-- 'pkgState' in 'DynFlags' and return a list of packages to
-- link in.
initPackages :: DynFlags -> IO (DynFlags, [PackageId])
initPackages dflags = do 
  pkg_db <- case pkgDatabase dflags of
                Nothing -> readPackageConfigs dflags
                Just db -> return $ maybeHidePackages dflags db
  (pkg_state, preload, this_pkg)       
        <- mkPackageState dflags pkg_db [] (thisPackage dflags)
  return (dflags{ pkgDatabase = Just pkg_db,
		  pkgState = pkg_state,
                  thisPackage = this_pkg },
          preload)

-- -----------------------------------------------------------------------------
-- Reading the package database(s)

readPackageConfigs :: DynFlags -> IO [PackageConfig]
readPackageConfigs dflags = do
   e_pkg_path <- tryIO (getEnv "GHC_PACKAGE_PATH")
   system_pkgconfs <- getSystemPackageConfigs dflags

   let pkgconfs = case e_pkg_path of
		    Left _   -> system_pkgconfs
		    Right path
		     | last cs == "" -> init cs ++ system_pkgconfs
		     | otherwise     -> cs
		     where cs = parseSearchPath path
		     -- if the path ends in a separator (eg. "/foo/bar:")
		     -- the we tack on the system paths.

   pkgs <- mapM (readPackageConfig dflags)
                (pkgconfs ++ reverse (extraPkgConfs dflags))
                -- later packages shadow earlier ones.  extraPkgConfs
                -- is in the opposite order to the flags on the
                -- command line.

   return (concat pkgs)


getSystemPackageConfigs :: DynFlags -> IO [FilePath]
getSystemPackageConfigs dflags = do
	-- System one always comes first
   let system_pkgconf = systemPackageConfig dflags

	-- Read user's package conf (eg. ~/.ghc/i386-linux-6.3/package.conf)
	-- unless the -no-user-package-conf flag was given.
   user_pkgconf <- do
      if not (dopt Opt_ReadUserPackageConf dflags) then return [] else do
      appdir <- getAppUserDataDirectory "ghc"
      let 
     	 dir = appdir </> (TARGET_ARCH ++ '-':TARGET_OS ++ '-':cProjectVersion)
         pkgconf = dir </> "package.conf.d"
      --
      exist <- doesDirectoryExist pkgconf
      if exist then return [pkgconf] else return []
    `catchIO` (\_ -> return [])

   return (system_pkgconf : user_pkgconf)

readPackageConfig :: DynFlags -> FilePath -> IO [PackageConfig]
readPackageConfig dflags conf_file = do
  isdir <- doesDirectoryExist conf_file

  proto_pkg_configs <- 
    if isdir
       then do let filename = conf_file </> "package.cache"
               debugTraceMsg dflags 2 (text "Using binary package database:" <+> text filename)
               conf <- readBinPackageDB filename
               return (map installedPackageInfoToPackageConfig conf)

       else do 
            isfile <- doesFileExist conf_file
            when (not isfile) $
              ghcError $ InstallationError $ 
                "can't find a package database at " ++ conf_file
            debugTraceMsg dflags 2 (text "Using package config file:" <+> text conf_file)
            str <- readFile conf_file
            return (map installedPackageInfoToPackageConfig $ read str)

  let
      top_dir = topDir dflags
      pkg_configs1 = mungePackagePaths top_dir proto_pkg_configs
      pkg_configs2 = maybeHidePackages dflags pkg_configs1
  --
  return pkg_configs2

maybeHidePackages :: DynFlags -> [PackageConfig] -> [PackageConfig]
maybeHidePackages dflags pkgs
  | dopt Opt_HideAllPackages dflags = map hide pkgs
  | otherwise 			    = pkgs
  where
    hide pkg = pkg{ exposed = False }

mungePackagePaths :: String -> [PackageConfig] -> [PackageConfig]
-- Replace the string "$topdir" at the beginning of a path
-- with the current topdir (obtained from the -B option).
mungePackagePaths top_dir ps = map munge_pkg ps
 where 
  munge_pkg p = p{ importDirs  = munge_paths (importDirs p),
		   includeDirs = munge_paths (includeDirs p),
    		   libraryDirs = munge_paths (libraryDirs p),
		   frameworkDirs = munge_paths (frameworkDirs p),
                   haddockInterfaces = munge_paths (haddockInterfaces p),
	           haddockHTMLs = munge_paths (haddockHTMLs p)
                    }

  munge_paths = map munge_path

  munge_path p 
	  | Just p' <- stripPrefix "$topdir"     p =            top_dir ++ p'
	  | Just p' <- stripPrefix "$httptopdir" p = toHttpPath top_dir ++ p'
	  | otherwise				    = p

  toHttpPath p = "file:///" ++ p


-- -----------------------------------------------------------------------------
-- Modify our copy of the package database based on a package flag
-- (-package, -hide-package, -ignore-package).

applyPackageFlag
   :: UnusablePackages
   -> [PackageConfig]           -- Initial database
   -> PackageFlag               -- flag to apply
   -> IO [PackageConfig]        -- new database

applyPackageFlag unusable pkgs flag =
  case flag of
    ExposePackage str ->
       case selectPackages (matchingStr str) pkgs unusable of
         Left ps         -> packageFlagErr flag ps
         Right (p:ps,qs) -> return (p':ps')
    	  where p' = p {exposed=True}
    	        ps' = hideAll (pkgName (sourcePackageId p)) (ps++qs)
         _ -> panic "applyPackageFlag"

    ExposePackageId str ->
       case selectPackages (matchingId str) pkgs unusable of
         Left ps         -> packageFlagErr flag ps
         Right (p:ps,qs) -> return (p':ps')
    	  where p' = p {exposed=True}
    	        ps' = hideAll (pkgName (sourcePackageId p)) (ps++qs)
         _ -> panic "applyPackageFlag"

    HidePackage str ->
       case selectPackages (matchingStr str) pkgs unusable of
         Left ps       -> packageFlagErr flag ps
         Right (ps,qs) -> return (map hide ps ++ qs)
    	  where hide p = p {exposed=False}

    _ -> panic "applyPackageFlag"

   where
	-- When a package is requested to be exposed, we hide all other
	-- packages with the same name.
	hideAll name ps = map maybe_hide ps
	  where maybe_hide p
                   | pkgName (sourcePackageId p) == name = p {exposed=False}
                   | otherwise                           = p


selectPackages :: (PackageConfig -> Bool) -> [PackageConfig]
               -> UnusablePackages
               -> Either [(PackageConfig, UnusablePackageReason)]
                  ([PackageConfig], [PackageConfig])
selectPackages matches pkgs unusable
  = let
        (ps,rest) = partition matches pkgs
        reasons = [ (p, Map.lookup (installedPackageId p) unusable)
                  | p <- ps ]
    in
    if all (isJust.snd) reasons
       then Left  [ (p, reason) | (p,Just reason) <- reasons ]
       else Right (sortByVersion [ p | (p,Nothing) <- reasons ], rest)

-- A package named on the command line can either include the
-- version, or just the name if it is unambiguous.
matchingStr :: String -> PackageConfig -> Bool
matchingStr str p
	=  str == display (sourcePackageId p)
	|| str == display (pkgName (sourcePackageId p))

matchingId :: String -> PackageConfig -> Bool
matchingId str p =  InstalledPackageId str == installedPackageId p

sortByVersion :: [InstalledPackageInfo_ m] -> [InstalledPackageInfo_ m]
sortByVersion = sortBy (flip (comparing (pkgVersion.sourcePackageId)))

comparing :: Ord a => (t -> a) -> t -> t -> Ordering
comparing f a b = f a `compare` f b

packageFlagErr :: PackageFlag
               -> [(PackageConfig, UnusablePackageReason)]
               -> IO a

-- for missing DPH package we emit a more helpful error message, because
-- this may be the result of using -fdph-par or -fdph-seq.
packageFlagErr (ExposePackage pkg) [] | is_dph_package pkg
  = ghcError (CmdLineError (showSDoc $ dph_err))
  where dph_err = text "the " <> text pkg <> text " package is not installed."
                  $$ text "To install it: \"cabal install dph\"."
        is_dph_package pkg = "dph" `isPrefixOf` pkg
  
packageFlagErr flag reasons = ghcError (CmdLineError (showSDoc $ err))
  where err = text "cannot satisfy " <> ppr_flag <> 
                (if null reasons then empty else text ": ") $$
              nest 4 (ppr_reasons $$
                      text "(use -v for more information)")
        ppr_flag = case flag of
                     IgnorePackage p -> text "-ignore-package " <> text p
                     HidePackage p   -> text "-hide-package " <> text p
                     ExposePackage p -> text "-package " <> text p
                     ExposePackageId p -> text "-package-id " <> text p
        ppr_reasons = vcat (map ppr_reason reasons)
        ppr_reason (p, reason) = pprReason (pprIPkg p <+> text "is") reason

-- -----------------------------------------------------------------------------
-- Hide old versions of packages

--
-- hide all packages for which there is also a later version
-- that is already exposed.  This just makes it non-fatal to have two
-- versions of a package exposed, which can happen if you install a
-- later version of a package in the user database, for example.
--
hideOldPackages :: DynFlags -> [PackageConfig] -> IO [PackageConfig]
hideOldPackages dflags pkgs = mapM maybe_hide pkgs
  where maybe_hide p
	   | not (exposed p) = return p
	   | (p' : _) <- later_versions = do
		debugTraceMsg dflags 2 $
		   (ptext (sLit "hiding package") <+> pprSPkg p <+>
		    ptext (sLit "to avoid conflict with later version") <+>
		    pprSPkg p')
		return (p {exposed=False})
	   | otherwise = return p
	  where myname = pkgName (sourcePackageId p)
		myversion = pkgVersion (sourcePackageId p)
		later_versions = [ p | p <- pkgs, exposed p,
				    let pkg = sourcePackageId p,
				    pkgName pkg == myname,
				    pkgVersion pkg > myversion ]

-- -----------------------------------------------------------------------------
-- Wired-in packages

findWiredInPackages
   :: DynFlags
   -> [PackageConfig]           -- database
   -> IO [PackageConfig]

findWiredInPackages dflags pkgs = do
  --
  -- Now we must find our wired-in packages, and rename them to
  -- their canonical names (eg. base-1.0 ==> base).
  --
  let
        wired_in_pkgids :: [String]
        wired_in_pkgids = map packageIdString
                          [ primPackageId,
                            integerPackageId,
                            basePackageId,
                            rtsPackageId,
                            thPackageId,
                            dphSeqPackageId,
                            dphParPackageId ]

        matches :: PackageConfig -> String -> Bool
        pc `matches` pid = display (pkgName (sourcePackageId pc)) == pid

	-- find which package corresponds to each wired-in package
	-- delete any other packages with the same name
	-- update the package and any dependencies to point to the new
	-- one.
        --
        -- When choosing which package to map to a wired-in package
        -- name, we prefer exposed packages, and pick the latest
        -- version.  To override the default choice, -hide-package
        -- could be used to hide newer versions.
        --
	findWiredInPackage :: [PackageConfig] -> String
			   -> IO (Maybe InstalledPackageId)
	findWiredInPackage pkgs wired_pkg =
           let all_ps = [ p | p <- pkgs, p `matches` wired_pkg ] in
	   case all_ps of
		[]   -> notfound
		many -> pick (head (sortByVersion many))
          where
                notfound = do
			  debugTraceMsg dflags 2 $
			    ptext (sLit "wired-in package ")
				 <> text wired_pkg
				 <> ptext (sLit " not found.")
			  return Nothing
		pick :: InstalledPackageInfo_ ModuleName
                     -> IO (Maybe InstalledPackageId)
                pick pkg = do
                        debugTraceMsg dflags 2 $
			    ptext (sLit "wired-in package ")
				 <> text wired_pkg
				 <> ptext (sLit " mapped to ")
				 <> pprIPkg pkg
			return (Just (installedPackageId pkg))


  mb_wired_in_ids <- mapM (findWiredInPackage pkgs) wired_in_pkgids
  let 
        wired_in_ids = catMaybes mb_wired_in_ids

        -- this is old: we used to assume that if there were
        -- multiple versions of wired-in packages installed that
        -- they were mutually exclusive.  Now we're assuming that
        -- you have one "main" version of each wired-in package
        -- (the latest version), and the others are backward-compat
        -- wrappers that depend on this one.  e.g. base-4.0 is the
        -- latest, base-3.0 is a compat wrapper depending on base-4.0.
        {-
 	deleteOtherWiredInPackages pkgs = filterOut bad pkgs
 	  where bad p = any (p `matches`) wired_in_pkgids
                      && package p `notElem` map fst wired_in_ids
        -}

	updateWiredInDependencies pkgs = map upd_pkg pkgs
	  where upd_pkg p
                  | installedPackageId p `elem` wired_in_ids
                  = p { sourcePackageId = (sourcePackageId p){ pkgVersion = Version [] [] } }
                  | otherwise
                  = p

  return $ updateWiredInDependencies pkgs

-- ----------------------------------------------------------------------------

data UnusablePackageReason
  = IgnoredWithFlag
  | MissingDependencies [InstalledPackageId]
  | ShadowedBy InstalledPackageId

type UnusablePackages = Map InstalledPackageId UnusablePackageReason

pprReason :: SDoc -> UnusablePackageReason -> SDoc
pprReason pref reason = case reason of
  IgnoredWithFlag ->
      pref <+> ptext (sLit "ignored due to an -ignore-package flag")
  MissingDependencies deps ->
      pref <+>
      ptext (sLit "unusable due to missing or recursive dependencies:") $$
        nest 2 (hsep (map (text.display) deps))
  ShadowedBy ipid ->
      pref <+> ptext (sLit "shadowed by package ") <> text (display ipid)

reportUnusable :: DynFlags -> UnusablePackages -> IO ()
reportUnusable dflags pkgs = mapM_ report (Map.toList pkgs)
  where
    report (ipid, reason) =
       debugTraceMsg dflags 2 $
         pprReason
           (ptext (sLit "package") <+>
            text (display ipid) <+> text "is") reason

-- ----------------------------------------------------------------------------
--
-- Detect any packages that have missing dependencies, and also any
-- mutually-recursive groups of packages (loops in the package graph
-- are not allowed).  We do this by taking the least fixpoint of the
-- dependency graph, repeatedly adding packages whose dependencies are
-- satisfied until no more can be added.
--
findBroken :: [PackageConfig] -> UnusablePackages
findBroken pkgs = go [] Map.empty pkgs
 where
   go avail ipids not_avail =
     case partitionWith (depsAvailable ipids) not_avail of
        ([], not_avail) ->
            Map.fromList [ (installedPackageId p, MissingDependencies deps)
                         | (p,deps) <- not_avail ]
        (new_avail, not_avail) ->
            go (new_avail ++ avail) new_ipids (map fst not_avail)
            where new_ipids = Map.insertList
                                [ (installedPackageId p, p) | p <- new_avail ]
                                ipids

   depsAvailable :: InstalledPackageIndex
                 -> PackageConfig
                 -> Either PackageConfig (PackageConfig, [InstalledPackageId])
   depsAvailable ipids pkg
        | null dangling = Left pkg
        | otherwise     = Right (pkg, dangling)
        where dangling = filter (not . (`Map.member` ipids)) (depends pkg)

-- -----------------------------------------------------------------------------
-- Eliminate shadowed packages, giving the user some feedback

-- later packages in the list should shadow earlier ones with the same
-- package name/version.  Additionally, a package may be preferred if
-- it is in the transitive closure of packages selected using -package-id
-- flags.
shadowPackages :: [PackageConfig] -> [InstalledPackageId] -> UnusablePackages
shadowPackages pkgs preferred
 = let (shadowed,_) = foldl check ([],emptyUFM) pkgs
   in  Map.fromList shadowed
 where
 check (shadowed,pkgmap) pkg
      | Just oldpkg <- lookupUFM pkgmap (packageConfigId pkg)
      , let
            ipid_new = installedPackageId pkg
            ipid_old = installedPackageId oldpkg
        --
      , ipid_old /= ipid_new
      = if ipid_old `elem` preferred
           then ( (ipid_new, ShadowedBy ipid_old) : shadowed, pkgmap )
           else ( (ipid_old, ShadowedBy ipid_new) : shadowed, pkgmap' )
      | otherwise
      = (shadowed, pkgmap')
      where
        pkgmap' = addToUFM pkgmap (packageConfigId pkg) pkg

-- -----------------------------------------------------------------------------

ignorePackages :: [PackageFlag] -> [PackageConfig] -> UnusablePackages
ignorePackages flags pkgs = Map.fromList (concatMap doit flags)
  where
  doit (IgnorePackage str) =
     case partition (matchingStr str) pkgs of
         (ps, _) -> [ (installedPackageId p, IgnoredWithFlag)
                    | p <- ps ]
    	-- missing package is not an error for -ignore-package,
    	-- because a common usage is to -ignore-package P as
    	-- a preventative measure just in case P exists.
  doit _ = panic "ignorePackages"

-- -----------------------------------------------------------------------------

depClosure :: InstalledPackageIndex
           -> [InstalledPackageId]
           -> [InstalledPackageId]
depClosure index ipids = closure Map.empty ipids
  where
   closure set [] = Map.keys set
   closure set (ipid : ipids)
     | ipid `Map.member` set = closure set ipids
     | Just p <- Map.lookup ipid index = closure (Map.insert ipid p set) 
                                                 (depends p ++ ipids)
     | otherwise = closure set ipids

-- -----------------------------------------------------------------------------
-- When all the command-line options are in, we can process our package
-- settings and populate the package state.

mkPackageState
    :: DynFlags
    -> [PackageConfig]          -- initial database
    -> [PackageId]              -- preloaded packages
    -> PackageId                -- this package
    -> IO (PackageState,
           [PackageId],         -- new packages to preload
           PackageId) -- this package, might be modified if the current

                      -- package is a wired-in package.

mkPackageState dflags pkgs0 preload0 this_package = do

{-
   Plan.

   1. P = transitive closure of packages selected by -package-id 

   2. Apply shadowing.  When there are multiple packages with the same
      sourcePackageId,
        * if one is in P, use that one
        * otherwise, use the one highest in the package stack
      [
       rationale: we cannot use two packages with the same sourcePackageId
       in the same program, because sourcePackageId is the symbol prefix.
       Hence we must select a consistent set of packages to use.  We have
       a default algorithm for doing this: packages higher in the stack
       shadow those lower down.  This default algorithm can be overriden
       by giving explicit -package-id flags; then we have to take these
       preferences into account when selecting which other packages are
       made available.

       Our simple algorithm throws away some solutions: there may be other
       consistent sets that would satisfy the -package flags, but it's
       not GHC's job to be doing constraint solving.
      ]

   3. remove packages selected by -ignore-package

   4. remove any packages with missing dependencies, or mutually recursive
      dependencies.

   5. report (with -v) any packages that were removed by steps 2-4

   6. apply flags to set exposed/hidden on the resulting packages
      - if any flag refers to a package which was removed by 2-4, then
        we can give an error message explaining why

   7. hide any packages which are superseded by later exposed packages
-}

  let
      flags = reverse (packageFlags dflags)

      -- pkgs0 with duplicate packages filtered out.  This is
      -- important: it is possible for a package in the global package
      -- DB to have the same IPID as a package in the user DB, and
      -- we want the latter to take precedence.  This is not the same
      -- as shadowing (below), since in this case the two packages
      -- have the same ABI and are interchangeable.
      --
      -- #4072: note that we must retain the ordering of the list here
      -- so that shadowing behaves as expected when we apply it later.
      pkgs0_unique = snd $ foldr del (Set.empty,[]) pkgs0
          where del p (s,ps)
                  | pid `Set.member` s = (s,ps)
                  | otherwise          = (Set.insert pid s, p:ps)
                  where pid = installedPackageId p
          -- XXX this is just a variant of nub

      ipid_map = Map.fromList [ (installedPackageId p, p) | p <- pkgs0 ]

      ipid_selected = depClosure ipid_map [ InstalledPackageId i
                                          | ExposePackageId i <- flags ]
      
      (ignore_flags, other_flags) = partition is_ignore flags
      is_ignore IgnorePackage{} = True
      is_ignore _ = False

      shadowed = shadowPackages pkgs0_unique ipid_selected

      ignored  = ignorePackages ignore_flags pkgs0_unique

      pkgs0' = filter (not . (`Map.member` (Map.union shadowed ignored)) . installedPackageId) pkgs0_unique
      broken   = findBroken pkgs0'
      unusable = shadowed `Map.union` ignored `Map.union` broken

  reportUnusable dflags unusable

  --
  -- Modify the package database according to the command-line flags
  -- (-package, -hide-package, -ignore-package, -hide-all-packages).
  --
  pkgs1 <- foldM (applyPackageFlag unusable) pkgs0_unique other_flags
  let pkgs2 = filter (not . (`Map.member` unusable) . installedPackageId) pkgs1

  -- Here we build up a set of the packages mentioned in -package
  -- flags on the command line; these are called the "preload"
  -- packages.  we link these packages in eagerly.  The preload set
  -- should contain at least rts & base, which is why we pretend that
  -- the command line contains -package rts & -package base.
  --
  let preload1 = [ installedPackageId p | f <- flags, p <- get_exposed f ]

      get_exposed (ExposePackage   s) = filter (matchingStr s) pkgs2
      get_exposed (ExposePackageId s) = filter (matchingId  s) pkgs2
      get_exposed _                   = []

  -- hide packages that are subsumed by later versions
  pkgs3 <- hideOldPackages dflags pkgs2

  -- sort out which packages are wired in
  pkgs4 <- findWiredInPackages dflags pkgs3

  let pkg_db = extendPackageConfigMap emptyPackageConfigMap pkgs4

      ipid_map = Map.fromList [ (installedPackageId p, packageConfigId p)
                              | p <- pkgs4 ]

      lookupIPID ipid@(InstalledPackageId str)
         | Just pid <- Map.lookup ipid ipid_map = return pid
         | otherwise                            = missingPackageErr str

  preload2 <- mapM lookupIPID preload1

  let
      -- add base & rts to the preload packages
      basicLinkedPackages
       | dopt Opt_AutoLinkPackages dflags
          = filter (flip elemUFM pkg_db) [basePackageId, rtsPackageId]
       | otherwise = []
      -- but in any case remove the current package from the set of
      -- preloaded packages so that base/rts does not end up in the
      -- set up preloaded package when we are just building it
      preload3 = nub $ filter (/= this_package)
                     $ (basicLinkedPackages ++ preload2)

  -- Close the preload packages with their dependencies
  dep_preload <- closeDeps pkg_db ipid_map (zip preload3 (repeat Nothing))
  let new_dep_preload = filter (`notElem` preload0) dep_preload

  let pstate = PackageState{ preloadPackages     = dep_preload,
		             pkgIdMap   	 = pkg_db,
		             moduleToPkgConfAll  = mkModuleMap pkg_db,
                             installedPackageIdMap = ipid_map
		           }

  return (pstate, new_dep_preload, this_package)


-- -----------------------------------------------------------------------------
-- Make the mapping from module to package info

mkModuleMap
  :: PackageConfigMap
  -> UniqFM [(PackageConfig, Bool)]
mkModuleMap pkg_db = foldr extend_modmap emptyUFM pkgids
  where
        pkgids = map packageConfigId (eltsUFM pkg_db)
        
	extend_modmap pkgid modmap =
		addListToUFM_C (++) modmap 
		   ([(m, [(pkg, True)])  | m <- exposed_mods] ++
		    [(m, [(pkg, False)]) | m <- hidden_mods])
	  where
		pkg = expectJust "mkModuleMap" (lookupPackage pkg_db pkgid)
	        exposed_mods = exposedModules pkg
	        hidden_mods  = hiddenModules pkg

pprSPkg :: PackageConfig -> SDoc
pprSPkg p = text (display (sourcePackageId p))

pprIPkg :: PackageConfig -> SDoc
pprIPkg p = text (display (installedPackageId p))

-- -----------------------------------------------------------------------------
-- Extracting information from the packages in scope

-- Many of these functions take a list of packages: in those cases,
-- the list is expected to contain the "dependent packages",
-- i.e. those packages that were found to be depended on by the
-- current module/program.  These can be auto or non-auto packages, it
-- doesn't really matter.  The list is always combined with the list
-- of preload (command-line) packages to determine which packages to
-- use.

-- | Find all the include directories in these and the preload packages
getPackageIncludePath :: DynFlags -> [PackageId] -> IO [String]
getPackageIncludePath dflags pkgs =
  collectIncludeDirs `fmap` getPreloadPackagesAnd dflags pkgs

collectIncludeDirs :: [PackageConfig] -> [FilePath] 
collectIncludeDirs ps = nub (filter notNull (concatMap includeDirs ps))

-- | Find all the library paths in these and the preload packages
getPackageLibraryPath :: DynFlags -> [PackageId] -> IO [String]
getPackageLibraryPath dflags pkgs =
  collectLibraryPaths `fmap` getPreloadPackagesAnd dflags pkgs

collectLibraryPaths :: [PackageConfig] -> [FilePath]
collectLibraryPaths ps = nub (filter notNull (concatMap libraryDirs ps))

-- | Find all the link options in these and the preload packages
getPackageLinkOpts :: DynFlags -> [PackageId] -> IO [String]
getPackageLinkOpts dflags pkgs = 
  collectLinkOpts dflags `fmap` getPreloadPackagesAnd dflags pkgs

collectLinkOpts :: DynFlags -> [PackageConfig] -> [String]
collectLinkOpts dflags ps = concat (map all_opts ps)
  where
      	libs p     = packageHsLibs dflags p ++ extraLibraries p
	all_opts p = map ("-l" ++) (libs p) ++ ldOptions p

packageHsLibs :: DynFlags -> PackageConfig -> [String]
packageHsLibs dflags p = map (mkDynName . addSuffix) (hsLibraries p)
  where
        ways0 = ways dflags

        ways1 = filter ((/= WayDyn) . wayName) ways0
        -- the name of a shared library is libHSfoo-ghc<version>.so
        -- we leave out the _dyn, because it is superfluous

        -- debug RTS includes support for -eventlog
        ways2 | WayDebug `elem` map wayName ways1 
              = filter ((/= WayEventLog) . wayName) ways1
              | otherwise
              = ways1

        tag     = mkBuildTag (filter (not . wayRTSOnly) ways2)
        rts_tag = mkBuildTag ways2

	mkDynName | opt_Static = id
		  | otherwise = (++ ("-ghc" ++ cProjectVersion))

        addSuffix rts@"HSrts"    = rts       ++ (expandTag rts_tag)
        addSuffix other_lib      = other_lib ++ (expandTag tag)

        expandTag t | null t = ""
		    | otherwise = '_':t

-- | Find all the C-compiler options in these and the preload packages
getPackageExtraCcOpts :: DynFlags -> [PackageId] -> IO [String]
getPackageExtraCcOpts dflags pkgs = do
  ps <- getPreloadPackagesAnd dflags pkgs
  return (concatMap ccOptions ps)

-- | Find all the package framework paths in these and the preload packages
getPackageFrameworkPath  :: DynFlags -> [PackageId] -> IO [String]
getPackageFrameworkPath dflags pkgs = do
  ps <- getPreloadPackagesAnd dflags pkgs
  return (nub (filter notNull (concatMap frameworkDirs ps)))

-- | Find all the package frameworks in these and the preload packages
getPackageFrameworks  :: DynFlags -> [PackageId] -> IO [String]
getPackageFrameworks dflags pkgs = do
  ps <- getPreloadPackagesAnd dflags pkgs
  return (concatMap frameworks ps)

-- -----------------------------------------------------------------------------
-- Package Utils

-- | Takes a 'Module', and if the module is in a package returns 
-- @(pkgconf, exposed)@ where pkgconf is the PackageConfig for that package,
-- and exposed is @True@ if the package exposes the module.
lookupModuleInAllPackages :: DynFlags -> ModuleName -> [(PackageConfig,Bool)]
lookupModuleInAllPackages dflags m =
  case lookupUFM (moduleToPkgConfAll (pkgState dflags)) m of
	Nothing -> []
	Just ps -> ps

-- | Find all the 'PackageConfig' in both the preload packages from 'DynFlags' and corresponding to the list of
-- 'PackageConfig's
getPreloadPackagesAnd :: DynFlags -> [PackageId] -> IO [PackageConfig]
getPreloadPackagesAnd dflags pkgids =
  let 
      state   = pkgState dflags
      pkg_map = pkgIdMap state
      ipid_map = installedPackageIdMap state
      preload = preloadPackages state
      pairs = zip pkgids (repeat Nothing)
  in do
  all_pkgs <- throwErr (foldM (add_package pkg_map ipid_map) preload pairs)
  return (map (getPackageDetails state) all_pkgs)

-- Takes a list of packages, and returns the list with dependencies included,
-- in reverse dependency order (a package appears before those it depends on).
closeDeps :: PackageConfigMap
          -> Map InstalledPackageId PackageId
          -> [(PackageId, Maybe PackageId)]
          -> IO [PackageId]
closeDeps pkg_map ipid_map ps = throwErr (closeDepsErr pkg_map ipid_map ps)

throwErr :: MaybeErr Message a -> IO a
throwErr m = case m of
		Failed e    -> ghcError (CmdLineError (showSDoc e))
		Succeeded r -> return r

closeDepsErr :: PackageConfigMap
             -> Map InstalledPackageId PackageId
             -> [(PackageId,Maybe PackageId)]
             -> MaybeErr Message [PackageId]
closeDepsErr pkg_map ipid_map ps = foldM (add_package pkg_map ipid_map) [] ps

-- internal helper
add_package :: PackageConfigMap 
            -> Map InstalledPackageId PackageId
            -> [PackageId]
            -> (PackageId,Maybe PackageId)
            -> MaybeErr Message [PackageId]
add_package pkg_db ipid_map ps (p, mb_parent)
  | p `elem` ps = return ps	-- Check if we've already added this package
  | otherwise =
      case lookupPackage pkg_db p of
        Nothing -> Failed (missingPackageMsg (packageIdString p) <> 
                           missingDependencyMsg mb_parent)
        Just pkg -> do
    	   -- Add the package's dependents also
    	   ps' <- foldM add_package_ipid ps (depends pkg)
    	   return (p : ps')
          where
            add_package_ipid ps ipid@(InstalledPackageId str)
              | Just pid <- Map.lookup ipid ipid_map
              = add_package pkg_db ipid_map ps (pid, Just p)
              | otherwise
              = Failed (missingPackageMsg str <> missingDependencyMsg mb_parent)

missingPackageErr :: String -> IO a
missingPackageErr p = ghcError (CmdLineError (showSDoc (missingPackageMsg p)))

missingPackageMsg :: String -> SDoc
missingPackageMsg p = ptext (sLit "unknown package:") <+> text p

missingDependencyMsg :: Maybe PackageId -> SDoc
missingDependencyMsg Nothing = empty
missingDependencyMsg (Just parent)
  = space <> parens (ptext (sLit "dependency of") <+> ftext (packageIdFS parent))

-- -----------------------------------------------------------------------------

-- | Will the 'Name' come from a dynamically linked library?
isDllName :: PackageId -> Name -> Bool
-- Despite the "dll", I think this function just means that
-- the synbol comes from another dynamically-linked package,
-- and applies on all platforms, not just Windows
isDllName this_pkg name
  | opt_Static = False
  | Just mod <- nameModule_maybe name = modulePackageId mod /= this_pkg
  | otherwise = False  -- no, it is not even an external name

-- -----------------------------------------------------------------------------
-- Displaying packages

-- | Show package info on console, if verbosity is >= 3
dumpPackages :: DynFlags -> IO ()
dumpPackages dflags
  = do  let pkg_map = pkgIdMap (pkgState dflags)
	putMsg dflags $
              vcat (map (text . showInstalledPackageInfo
                              . packageConfigToInstalledPackageInfo)
                        (eltsUFM pkg_map))
\end{code}