🚀 go-pugleaf

GCC warns about an alignment problem when casting from a pointer to an
unknown struct to another pointer on machines where STRICT_ALIGNMENT
is defined (eg. m68k).  I don't think this warning is usefull, since
the compiler doesn't know the actual alignment restriction of such a
type, and it is similar to a pointer to void (which doesn't generate
this warning).


--------------------
struct opaque *foo;

f ()
{
  g ((int *) foo);
}
--------------------
$ gcc -c align.c -Wcast-align
align.c: In function `f':
align.c:5: warning: cast increases required alignment of target type


--- gcc-2.7.2/c-typeck.c.~1~	Mon Nov 20 19:24:42 1995
+++ gcc-2.7.2/c-typeck.c	Tue Dec 12 18:54:14 1995
@@ -3735,6 +3735,11 @@
 	  && TREE_CODE (otype) == POINTER_TYPE
 	  && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
 	  && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
+	  /* Don't warn about opaque types, where the actual alignment
+	     restriction is unknown.  */
+	  && !((TREE_CODE (TREE_TYPE (otype)) == UNION_TYPE
+		|| TREE_CODE (TREE_TYPE (otype)) == RECORD_TYPE)
+	       && TYPE_MODE (TREE_TYPE (otype)) == VOIDmode)
 	  && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
 	warning ("cast increases required alignment of target type");

-- 
Andreas Schwab                                      "And now for something
schwab@issan.informatik.uni-dortmund.de              completely different"