--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/format/ext-8.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,56 @@
+/* Test for scanf formats.  %m extensions.  */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wformat" } */
+
+#include "format.h"
+
+void
+foo (char **sp, wchar_t **lsp, int *ip, float *fp, void **pp)
+{
+  /* m assignment-allocation modifier, recognized in both C90
+     and C99 modes, is a POSIX and ISO/IEC WDTR 24731-2 extension.  */
+  scanf ("%ms", sp);
+  scanf ("%mS", lsp);
+  scanf ("%mls", lsp);
+  scanf ("%m[bcd]", sp);
+  scanf ("%ml[bcd]", lsp);
+  scanf ("%mc", sp);
+  scanf ("%mlc", lsp);
+  scanf ("%mC", lsp);
+  scanf ("%*ms");
+  scanf ("%*mS");
+  scanf ("%*mls");	/* { dg-warning "assignment suppression and length modifier" } */
+  scanf ("%*m[bcd]");
+  scanf ("%*ml[bcd]");	/* { dg-warning "assignment suppression and length modifier" } */
+  scanf ("%*mc");
+  scanf ("%*mlc");	/* { dg-warning "assignment suppression and length modifier" } */
+  scanf ("%*mC");
+  scanf ("%10ms", sp);
+  scanf ("%5mS", lsp);
+  scanf ("%9mls", lsp);
+  scanf ("%25m[bcd]", sp);
+  scanf ("%41ml[bcd]", lsp);
+  scanf ("%131mc", sp);
+  scanf ("%27mlc", lsp);
+  scanf ("%2mC", lsp);
+  scanf ("%*10ms");
+  scanf ("%*5mS");
+  scanf ("%*9mls");	/* { dg-warning "assignment suppression and length modifier" } */
+  scanf ("%*25m[bcd]");
+  scanf ("%*41ml[bcd]"); /* { dg-warning "assignment suppression and length modifier" } */
+  scanf ("%*131mc");
+  scanf ("%*27mlc");	/* { dg-warning "assignment suppression and length modifier" } */
+  scanf ("%*2mC");
+
+  scanf ("%md", ip);	/* { dg-warning "flag used with" } */
+  scanf ("%mi", ip);	/* { dg-warning "flag used with" } */
+  scanf ("%mo", ip);	/* { dg-warning "flag used with" } */
+  scanf ("%mu", ip);	/* { dg-warning "flag used with" } */
+  scanf ("%mx", ip);	/* { dg-warning "flag used with" } */
+  scanf ("%ma", fp);	/* { dg-warning "flag used with" } */
+  scanf ("%mA", fp);	/* { dg-warning "flag used with" } */
+  scanf ("%me", fp);	/* { dg-warning "flag used with" } */
+  scanf ("%mf", fp);	/* { dg-warning "flag used with" } */
+  scanf ("%mg", fp);	/* { dg-warning "flag used with" } */
+  scanf ("%mp", pp);	/* { dg-warning "flag used with" } */
+}