[commit: ghc] master: Use bracket in `withCurrentDirectory` (f14ac52)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/f14ac52a9296b378c75ea75c94f51ff1f377111e/ghc

>---------------------------------------------------------------

commit f14ac52a9296b378c75ea75c94f51ff1f377111e
Author: Konstantin Zudov <konstantin at anche.no>
Date:   Fri Nov 7 07:32:48 2014 -0600

    Use bracket in `withCurrentDirectory`
    
    Summary: There was a comment about that. Seems like a better behaviour.
    
    Reviewers: austin
    
    Reviewed By: austin
    
    Subscribers: thomie, carter, simonmar
    
    Differential Revision: https://phabricator.haskell.org/D419


>---------------------------------------------------------------

f14ac52a9296b378c75ea75c94f51ff1f377111e
 utils/ghc-cabal/Main.hs | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/utils/ghc-cabal/Main.hs b/utils/ghc-cabal/Main.hs
index bf08912..1847aaf 100644
--- a/utils/ghc-cabal/Main.hs
+++ b/utils/ghc-cabal/Main.hs
@@ -21,6 +21,7 @@ import Distribution.Verbosity
 import qualified Distribution.InstalledPackageInfo as Installed
 import qualified Distribution.Simple.PackageIndex as PackageIndex
 
+import Control.Exception (bracket)
 import Control.Monad
 import qualified Data.ByteString.Lazy.Char8 as BS
 import Data.List
@@ -70,14 +71,10 @@ die :: [String] -> IO a
 die errs = do mapM_ (hPutStrLn stderr) errs
               exitWith (ExitFailure 1)
 
--- XXX Should use bracket
 withCurrentDirectory :: FilePath -> IO a -> IO a
 withCurrentDirectory directory io
- = do curDirectory <- getCurrentDirectory
-      setCurrentDirectory directory
-      r <- io
-      setCurrentDirectory curDirectory
-      return r
+ = bracket (getCurrentDirectory) (setCurrentDirectory)
+           (const (setCurrentDirectory directory >> io))
 
 -- We need to use the autoconfUserHooks, as the packages that use
 -- configure can create a .buildinfo file, and we need any info that