--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/format/ext-2.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,73 @@
+/* Test for format extensions beyond the C standard and X/Open standard.
+   Test for scanf formats.
+*/
+/* Origin: Joseph Myers <jsm28@cam.ac.uk> */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wformat" } */
+
+#include "format.h"
+
+void
+foo (quad_t *qp, u_quad_t *uqp, quad_t *qn, long long int *llp,
+     unsigned long long int *ullp, float *fp, char *s, void **pp, wchar_t *ls,
+     int *ip, unsigned int *up)
+{
+  /* As an extension, GCC allows the BSD length "q" for integer formats.
+     This is largely obsoleted in C99 by %j, %ll and SCNd64.
+  */
+  scanf ("%qd%qi%qo%qu%qx%qX%qn", qp, qp, uqp, uqp, uqp, uqp, qn);
+  scanf ("%qf", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qF", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qe", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qE", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qg", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qG", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qa", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qA", fp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qs", s); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%q[abc]", s); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qc", s); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qp", pp); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qC", ls); /* { dg-warning "length" "bad use of %q" } */
+  scanf ("%qS", ls); /* { dg-warning "length" "bad use of %q" } */
+  /* As an extension, GCC allows the length "L" on integer formats
+     (but not %n) as a synonym for "ll".
+     This should be considered deprecated.
+  */
+  scanf ("%Ld%Li%Lo%Lu%Lx%LX", llp, llp, ullp, ullp, ullp, ullp);
+  /* glibc also supports flags ' and I on scanf formats.  The ' flag applies
+     to all formats scanning decimal values; the I flag only to decimal integer
+     formats.
+  */
+  scanf ("%'d%'i%'u%'a%'A%'e%'E%'f%'F%'g%'G", ip, ip, up, fp, fp, fp, fp,
+	 fp, fp, fp, fp);
+  scanf ("%'o", up); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'x", up); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'X", up); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'n", ip); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'s", s); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'[abc]", s); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'c", s); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'p", pp); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'C", ls); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%'S", ls); /* { dg-warning "flag" "bad use of ' flag" } */
+  scanf ("%Id%Ii%Iu", ip, ip, up);
+  scanf ("%Ia", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%IA", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%Ie", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%IE", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%If", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%IF", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%Ig", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%IG", fp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%Io", up); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%Ix", up); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%IX", up); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%In", ip); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%Is", s); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%I[abc]", s); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%Ic", s); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%Ip", pp); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%IC", ls); /* { dg-warning "flag" "bad use of I flag" } */
+  scanf ("%IS", ls); /* { dg-warning "flag" "bad use of I flag" } */
+}