--- p/types.c.orig	Sat Feb 19 16:11:11 2005
+++ p/types.c	Mon Feb 21 17:33:03 2005
@@ -1530,7 +1530,11 @@
     {
       if (why == MINUS_EXPR || why == PLUS_EXPR)
         {
-          int uns = TREE_UNSIGNED (TREE_TYPE (val1)) && TREE_UNSIGNED (TREE_TYPE (val2));
+          int uns1 = TREE_UNSIGNED (TREE_TYPE (val1))
+              || (TREE_CODE (val1) == INTEGER_CST && tree_int_cst_sgn (val1) >= 0);
+          int uns2 = TREE_UNSIGNED (TREE_TYPE (val2))
+              || (TREE_CODE (val2) == INTEGER_CST && tree_int_cst_sgn (val2) >= 0);
+          int uns = uns1 && uns2;
           int maxprec = MAX (TYPE_PRECISION (TREE_TYPE (val1)), TYPE_PRECISION (TREE_TYPE (val2)));
           /* The difference of two unsigned values should be done unsigned
              (otherwise there's no way to compute in the top range), but if