re PR c/80919 (ICE: Segmentation fault with -Wall when printing address of size 0 array)

	PR c/80919
	* c-format.c (matching_type_p): Return false if any of the types
	requires structural equality.

	* gcc.dg/format/pr80919.c: New test.

From-SVN: r248860

gcc/c-family/ChangeLog

+2017-06-04  Marek Polacek  <polacek@redhat.com>
+
+	PR c/80919
+	* c-format.c (matching_type_p): Return false if any of the types
+	requires structural equality.
+
 2017-06-02  Martin Sebor  <msebor@redhat.com>
 
 	PR c/80892

gcc/c-family/c-format.c

@@ -3278,6 +3278,12 @@ matching_type_p (tree spec_type, tree arg_type)
   gcc_assert (spec_type);
   gcc_assert (arg_type);
 
+  /* If any of the types requires structural equality, we can't compare
+     their canonical types.  */
+  if (TYPE_STRUCTURAL_EQUALITY_P (spec_type)
+      || TYPE_STRUCTURAL_EQUALITY_P (arg_type))
+    return false;
+
   spec_type = TYPE_CANONICAL (spec_type);
   arg_type = TYPE_CANONICAL (arg_type);
 

gcc/testsuite/ChangeLog

+2017-06-04  Marek Polacek  <polacek@redhat.com>
+
+	PR c/80919
+	* gcc.dg/format/pr80919.c: New test.
+
 2017-06-02  Martin Sebor  <msebor@redhat.com>
 
 	PR c/80892

gcc/testsuite/gcc.dg/format/pr80919.c

+/* PR c/80919 */
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+void
+fn (void)
+{
+  int a[0];
+  __builtin_printf("%d\n", &a); /* { dg-warning "expects argument of type" } */
+  __builtin_printf("%i\n", &a); /* { dg-warning "expects argument of type" } */
+
+  __builtin_printf("%o\n", &a); /* { dg-warning "expects argument of type" } */
+  __builtin_printf("%u\n", &a); /* { dg-warning "expects argument of type" } */
+  __builtin_printf("%x\n", &a); /* { dg-warning "expects argument of type" } */
+  __builtin_printf("%X\n", &a); /* { dg-warning "expects argument of type" } */
+}