Fix data type casting when setting up menus on Windows.

 src/w32menu.c (add_menu_item): Cast to UINT_PTR when assigning
 info.dwItemData.  Fixes crashes on 64-bit Windows.  Suggested by
 Fabrice Popineau <fabrice.popineau@supelec.fr>.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/w32menu.c b/src/w32menu.c
index 24dc9d79192..a5f4c3881b5 100644
--- a/src/w32menu.c
+++ b/src/w32menu.c
@@ -1533,7 +1533,14 @@ add_menu_item (HMENU menu, widget_value *wv, HMENU item)
              until it is ready to be displayed, since GC can happen while
              menus are active.  */
           if (!NILP (wv->help))
-            info.dwItemData = (DWORD) XLI (wv->help);
+            {
+              /* As of Jul-2012, w32api headers say that dwItemData
+                 has DWORD type, but that's a bug: it should actually
+                 be UINT_PTR, which is correct for 32-bit and 64-bit
+                 Windows alike.  MSVC headers get it right; hopefully,
+                 MinGW headers will, too.  */
+              info.dwItemData = (UINT_PTR) XLI (wv->help);
+            }
           if (wv->button_type == BUTTON_TYPE_RADIO)
             {
               /* CheckMenuRadioItem allows us to differentiate TOGGLE and