c-format.c (check_format_arg): Handle string literals of the form &"string"[offset].

2005-05-14  Richard Guenther  <rguenth@gcc.gnu.org>

	* c-format.c (check_format_arg): Handle string literals of
	the form &"string"[offset].

	* g++.dg/warn/format4.C: New testcase.

From-SVN: r99652

gcc/ChangeLog

+2005-05-13  Richard Guenther  <rguenth@gcc.gnu.org>
+
+	* c-format.c (check_format_arg): Handle string literals of
+	the form &"string"[offset].
+
+	* g++.dg/warn/format4.C: New testcase.
+
 2005-05-13  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* config/mips/3000.md, config/mips/4000.md,

gcc/c-format.c

@@ -1260,6 +1260,10 @@ check_format_arg (void *ctx, tree format_tree,
       return;
     }
   format_tree = TREE_OPERAND (format_tree, 0);
+  if (TREE_CODE (format_tree) == ARRAY_REF
+      && host_integerp (TREE_OPERAND (format_tree, 1), 0)
+      && (offset += tree_low_cst (TREE_OPERAND (format_tree, 1), 0)) >= 0)
+    format_tree = TREE_OPERAND (format_tree, 0);
   if (TREE_CODE (format_tree) == VAR_DECL
       && TREE_CODE (TREE_TYPE (format_tree)) == ARRAY_TYPE
       && (array_init = decl_constant_value (format_tree)) != format_tree

gcc/testsuite/g++.dg/warn/format4.C

+// { dg-do compile }
+// { dg-options "-Wformat=2" }
+
+extern "C" int printf (const char*, ...);
+
+void foo(int i)
+{
+	printf("Hello World %d!\n", i);
+	printf(&"Hello World %d!\n"[0], i);
+	printf(&"Hello World %d!\n"[6], i);
+	printf(&"Hello World %d!\n"[8]-2, i);
+	printf(&"Hello World %d!\n"[4]+2, i);
+}