X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=GHC%2FIO%2FHandle%2FInternals.hs;h=2aad185f756f8e556a8a8d32ae99ba7a438c36d7;hb=267f4516994e20eec23203214079102edc3a3262;hp=1e48e8bb434eaa9c1ed2e6afb1f10320e0f0add3;hpb=a72a7e3363c4f80e0f32906a35f25f112abaf09f;p=ghc-base.git

diff --git a/GHC/IO/Handle/Internals.hs b/GHC/IO/Handle/Internals.hs
index 1e48e8b..2aad185 100644
--- a/GHC/IO/Handle/Internals.hs
+++ b/GHC/IO/Handle/Internals.hs
@@ -220,7 +220,9 @@ wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
 wantWritableHandle fun h@(FileHandle _ m) act
   = wantWritableHandle' fun h m act
 wantWritableHandle fun h@(DuplexHandle _ _ m) act
-  = withHandle_' fun h m  act
+  = wantWritableHandle' fun h m act
+    -- we know it's not a ReadHandle or ReadWriteHandle, but we have to
+    -- check for ClosedHandle/SemiClosedHandle. (#4808)
 
 wantWritableHandle'
         :: String -> Handle -> MVar Handle__
@@ -257,7 +259,9 @@ wantReadableHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
 wantReadableHandle_ fun h@(FileHandle  _ m)   act
   = wantReadableHandle' fun h m act
 wantReadableHandle_ fun h@(DuplexHandle _ m _) act
-  = withHandle_' fun h m act
+  = wantReadableHandle' fun h m act
+    -- we know it's not a WriteHandle or ReadWriteHandle, but we have to
+    -- check for ClosedHandle/SemiClosedHandle. (#4808)
 
 wantReadableHandle'
         :: String -> Handle -> MVar Handle__