[glib/wip/pwithnall/1940-atomic-types: 2/3] gatomic: Check argument width in g_atomic_pointer_compare_and_exchange()

[Philip Withnall <pwithnall src gnome org>]

commit 75cd86f00e36484fd923d9e3bde7daa34514fa30
Author: Philip Withnall <withnall endlessm com>
Date:   Wed Nov 20 12:08:46 2019 +0000

    gatomic: Check argument width in g_atomic_pointer_compare_and_exchange()
    
    Check that the new value is actually pointer-width, rather than (for
    example) `sizeof (int)` which could happen if someone used `0` rather
    than `NULL`.
    
    Changes suggested by Simon McVittie.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    Helps: #1940

 glib/gatomic.h | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/glib/gatomic.h b/glib/gatomic.h
index 646a30df4..fb78c0cc1 100644
--- a/glib/gatomic.h
+++ b/glib/gatomic.h
@@ -187,6 +187,7 @@ G_END_DECLS
 
 #define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \
   (G_GNUC_EXTENSION ({                                                       \
+    G_STATIC_ASSERT (sizeof (oldval) == sizeof (gpointer));                  \
     __typeof__ ((oldval)) gapcae_oldval = (oldval);                          \
     G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer));                 \
     (void) (0 ? (gpointer) *(atomic) : NULL);                                \