[commit: Win32] master: EnumClipboardFormats returning 0 is not an error (#4452) (6c035c1)

[Paolo Capriotti]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/Win32

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/6c035c1fb7cb0bba64cdea3a3e1a84c19ef4cd18

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

commit 6c035c1fb7cb0bba64cdea3a3e1a84c19ef4cd18
Author: Paolo Capriotti <p.capriotti at gmail.com>
Date:   Wed May 9 14:29:28 2012 +0100

    EnumClipboardFormats returning 0 is not an error (#4452)

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

 Graphics/Win32/GDI/Clip.hsc |    8 ++++++--
 tests/T4452.hs              |   13 +++++++++++++
 tests/all.T                 |    1 +
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/Graphics/Win32/GDI/Clip.hsc b/Graphics/Win32/GDI/Clip.hsc
index 78a1eb7..f7d0ace 100644
--- a/Graphics/Win32/GDI/Clip.hsc
+++ b/Graphics/Win32/GDI/Clip.hsc
@@ -17,6 +17,7 @@
 
 module Graphics.Win32.GDI.Clip where
 
+import Control.Monad
 import Graphics.Win32.GDI.Types
 import System.Win32.Types
 
@@ -75,8 +76,11 @@ foreign import stdcall unsafe "windows.h EmptyClipboard"
 -- original also tested GetLastError() != NO_ERROR
 
 enumClipboardFormats :: ClipboardFormat -> IO ClipboardFormat
-enumClipboardFormats format =
-  failIfZero "EnumClipboardFormats" $ c_EnumClipboardFormats format
+enumClipboardFormats format = do
+  format' <- c_EnumClipboardFormats format
+  when (format' == 0) $
+    failUnlessSuccess "EnumClipboardFormats" getLastError
+  return format'
 foreign import stdcall unsafe "windows.h EnumClipboardFormats"
   c_EnumClipboardFormats :: ClipboardFormat -> IO ClipboardFormat
 
diff --git a/tests/T4452.hs b/tests/T4452.hs
new file mode 100644
index 0000000..551b32c
--- /dev/null
+++ b/tests/T4452.hs
@@ -0,0 +1,13 @@
+module Main where
+
+import Control.Monad
+import Foreign.Ptr
+import Graphics.Win32.GDI.Clip
+
+main = do
+  openClipboard nullPtr
+  go 0
+  where
+    go n = do
+      n' <- enumClipboardFormats n
+      unless (n == 0) (go n')
diff --git a/tests/all.T b/tests/all.T
index 589004c..07d030b 100644
--- a/tests/all.T
+++ b/tests/all.T
@@ -5,3 +5,4 @@ test('registry001', normal, compile_and_run, [''])
 test('helloworld', skip, compile_and_run, ['-package lang -package win32'])
 
 test('lasterror', normal, compile_and_run, ['-package Win32'])
+test('T4452', normal, compile_and_run, ['-package Win32'])