[commit: base] encoding: streamEncode was obviously wrong (33d015b)

[Max Bolingbroke]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/base

On branch  : encoding

http://hackage.haskell.org/trac/ghc/changeset/33d015b72c6a3c86f0e2396c06b66cf63c478c5d

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

commit 33d015b72c6a3c86f0e2396c06b66cf63c478c5d
Author: Max Bolingbroke <batterseapower at hotmail.com>
Date:   Mon Apr 11 17:47:07 2011 +0100

    streamEncode was obviously wrong

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

 GHC/IO/Handle/Internals.hs |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/GHC/IO/Handle/Internals.hs b/GHC/IO/Handle/Internals.hs
index e37902b..a2b644f 100644
--- a/GHC/IO/Handle/Internals.hs
+++ b/GHC/IO/Handle/Internals.hs
@@ -380,11 +380,12 @@ streamEncode codec from to = go (from, to)
   where 
     go (from, to) = do
       (why, from', to') <- encode codec from to
-      -- When we are dealing with Streams
+      -- When we are dealing with Handles, we don't care about input/output
+      -- underflow particularly, and we want to delay errors about invalid
+      -- sequences as far as possible.
       case why of
-        Encoding.InvalidSequence -> recover codec from to >>= go
-        Encoding.OutputUnderflow -> return (from', to')
-        Encoding.InputUnderflow  -> return (from', to')
+        Encoding.InvalidSequence | bufL from == bufL from' -> recover codec from' to' >>= go
+        _ -> return (from', to')
 
 -- -----------------------------------------------------------------------------
 -- Handle Finalizers