import System.FilePath
import Control.Monad
import Data.List as List
+import qualified Data.Set as Set
-- ---------------------------------------------------------------------------
-- The Package state
-- the we tack on the system paths.
pkgs <- mapM (readPackageConfig dflags)
- (reverse pkgconfs ++ reverse (extraPkgConfs dflags))
+ (pkgconfs ++ reverse (extraPkgConfs dflags))
-- later packages shadow earlier ones. extraPkgConfs
-- is in the opposite order to the flags on the
-- command line.
if exist then return [pkgconf] else return []
`catchIO` (\_ -> return [])
- return (user_pkgconf ++ [system_pkgconf])
+ return (system_pkgconf : user_pkgconf)
readPackageConfig :: DynFlags -> FilePath -> IO [PackageConfig]
readPackageConfig dflags conf_file = do
let
flags = reverse (packageFlags dflags)
- ipid_map = listToFM [ (installedPackageId p, p) | p <- pkgs0 ]
-
-- pkgs0 with duplicate packages filtered out. This is
- -- important: it is possible for a package in the user package
- -- DB to have the same IPID as a package in the global DB, and
- -- we want the former to take precedence. This is not the same
+ -- 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.
- pkgs0_unique = eltsFM ipid_map
+ --
+ -- #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 = listToFM [ (installedPackageId p, p) | p <- pkgs0 ]
ipid_selected = depClosure ipid_map [ InstalledPackageId i
| ExposePackageId i <- flags ]