EnumClipboardFormats returning 0 is not an error (#4452)

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
 

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')

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'])