From d1430fb505037999e8961fbd7e922d0e82eca0f1 Mon Sep 17 00:00:00 2001
From: simonmar <unknown>
Date: Tue, 6 Feb 2001 11:42:30 +0000
Subject: [PATCH] [project @ 2001-02-06 11:42:30 by simonmar] urk! when
 showing a handle, we don't replace the MVar.  For example,
 the following test causes a deadlock:

	main = do
	  getContents
	  catch getChar (\e -> print e >> return 'x')
	  catch getChar (\e -> print e >> return 'x')

To be merged into 4.08.
---
 ghc/lib/std/PrelIOBase.lhs |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/ghc/lib/std/PrelIOBase.lhs b/ghc/lib/std/PrelIOBase.lhs
index 02aad74..6ef3f27 100644
--- a/ghc/lib/std/PrelIOBase.lhs
+++ b/ghc/lib/std/PrelIOBase.lhs
@@ -1,5 +1,5 @@
 % ------------------------------------------------------------------------------
-% $Id: PrelIOBase.lhs,v 1.32 2001/01/11 17:25:57 simonmar Exp $
+% $Id: PrelIOBase.lhs,v 1.33 2001/02/06 11:42:30 simonmar Exp $
 % 
 % (c) The University of Glasgow, 1994-2000
 %
@@ -269,9 +269,10 @@ instance Show Handle where
      -- (Big) SIGH: unfolded defn of takeMVar to avoid
      -- an (oh-so) unfortunate module loop with PrelConc.
      hdl_ = unsafePerformIO (IO $ \ s# ->
-	     case h               of { MVar h# ->
-	     case takeMVar# h# s# of { (# s2# , r #) -> 
-		    (# s2#, r #) }})
+	     case h                 of { MVar h# ->
+	     case takeMVar# h# s#   of { (# s2# , r #) -> 
+	     case putMVar# h# r s2# of { s3# ->
+	     (# s3#, r #) }}})
 #endif
 #else
      hdl_ = unsafePerformIO (stToIO (readVar h))
-- 
1.7.10.4