1 files changed, 8 insertions, 5 deletions
diff --git a/gcc/builtins.c b/gcc/builtins.c
index 8621e0db511..067e3116faf 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -479,13 +479,16 @@ c_strlen (tree src, int only_value)
   else
     offset = tree_low_cst (offset_node, 0);
 
-  /* If the offset is known to be out of bounds, the front-end should
-     have warned already. We call strlen at runtime.  
-
-     ??? Perhaps we should turn this into an assert and force
-     front-ends to define offsets whtin boundaries.  */
+  /* If the offset is known to be out of bounds, warn, and call strlen at
+     runtime.  */
   if (offset < 0 || offset > max)
     {
+     /* Suppress multiple warnings for propagated constant strings.  */
+      if (! TREE_NO_WARNING (src))
+        {
+          warning (0, "offset outside bounds of constant string");
+          TREE_NO_WARNING (src) = 1;
+        }
       return NULL_TREE;
     }