PR tree-optimization/82596 - missing -Warray-bounds on an out-of-bounds

PR tree-optimization/82596 - missing -Warray-bounds on an out-of-bounds
  index into string literal

gcc/ChangeLog:
	* tree.c (array_at_struct_end_p): Handle STRING_CST.

gcc/testsuite/ChangeLog:
	* gcc/testsuite/gcc.dg/pr82596.c: New test.

From-SVN: r253902

gcc/ChangeLog

+2017-10-19  Martin Sebor  <msebor@redhat.com>
+
+	PR tree-optimization/82596
+	* tree.c (array_at_struct_end_p): Handle STRING_CST.
+
 2017-10-19  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* asan.c (handle_builtin_alloca): Deal with all alloca variants.

gcc/testsuite/ChangeLog

+2017-10-19  Martin Sebor  <msebor@redhat.com>
+
+	PR tree-optimization/82596
+	* gcc/testsuite/gcc.dg/pr82596.c: New test.
+
 2017-10-19  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gcc.dg/Walloca-15.c: New test.

gcc/testsuite/gcc.dg/pr82596.c

+/* PR tree-optimization/82596 - missing -Warray-bounds on an out-of-bounds
+   index into string literal
+   { dg-do compile }
+   { dg-options "-O2 -Warray-bounds" } */
+
+#define SIZE_MAX  __SIZE_MAX__
+#define SSIZE_MAX __PTRDIFF_MAX__
+#define SSIZE_MIN (-SSIZE_MAX - 1)
+
+void sink (int, ...);
+
+#define T(arg) sink (arg)
+
+void test_cststring (int i)
+{
+  T (""[SSIZE_MIN]);                      /* { dg-warning "below array bounds" "string" { xfail lp64 } } */
+  T (""[SSIZE_MIN + 1]);                  /* { dg-warning "below array bounds" "string" } */
+  T (""[-1]);                             /* { dg-warning "below array bounds" "string" } */
+  T (""[0]);
+  T (""[1]);                              /* { dg-warning "above array bounds" "string" } */
+  T ("0"[2]);                             /* { dg-warning "above array bounds" "string" } */
+  T ("012"[2]);
+  T ("012"[3]);
+  T ("012"[4]);                           /* { dg-warning "above array bounds" "string" } */
+  T ("0123"[SSIZE_MAX]);                  /* { dg-warning "above array bounds" "string" } */
+  T ("0123"[SIZE_MAX]);                   /* { dg-warning "above array bounds" "string" } */
+}

gcc/tree.c

@@ -12549,6 +12549,9 @@ array_at_struct_end_p (tree ref)
   else
     return false;
 
+  if (TREE_CODE (ref) == STRING_CST)
+    return false;
+
   while (handled_component_p (ref))
     {
       /* If the reference chain contains a component reference to a