--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/cpp/mi1.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,39 @@
+/* Test "ignore redundant include" facility.
+
+   We must test with C and C++ comments, and null directives, outside
+   the guard conditional; also, we test guarding with #ifndef and #if
+   !defined.  -H is used because cpp might confuse the issue by
+   optimizing out #line markers.  This test only passes if each of the
+   headers is read exactly once.
+
+   The disgusting regexp in the dg-error line, when stuck into
+   dg.exp's compiler-output regexp, matches the correct -H output and
+   only the correct -H output.  It has to be all on one line because
+   otherwise it will not be interpreted all in one unit.  */
+
+/* { dg-do compile }
+   { dg-options "-H" }
+   { dg-message "mi1c\.h\n\[^\n\]*mi1cc\.h\n\[^\n\]*mi1nd\.h\n\[^\n\]*mi1ndp\.h\n\[^\n\]*mi1x\.h" "redundant include check" { target *-*-* } 0 } */
+
+#include "mi1c.h"
+#include "mi1c.h"
+#include "mi1c.h"
+
+#include "mi1cc.h"
+#include "mi1cc.h"
+
+#include "mi1nd.h"
+#include "mi1nd.h"
+
+#include "mi1ndp.h"
+#include "mi1ndp.h"
+
+#define MIX_H
+#include "mi1x.h"
+#include "mi1x.h"
+
+int
+main (void)
+{
+  return a + b + c + d;
+}