--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/anon-struct-1.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,56 @@
+/* { dg-options "-std=iso9899:1990 -pedantic" } */
+/* In strict ISO C mode, we don't recognize the anonymous struct/union
+   extension or any Microsoft extensions.  */
+
+struct A { char a; };
+
+/* MS extension.  */
+struct B {
+  struct A;			/* { dg-warning "does not declare anything" } */
+  char b;
+};
+char testB[sizeof(struct B) == sizeof(struct A) ? 1 : -1];
+
+/* MS extension.  */
+struct C {
+  struct D { char d; };		/* { dg-warning "does not declare anything" } */
+  char c;
+};
+char testC[sizeof(struct C) == sizeof(struct A) ? 1 : -1];
+char testD[sizeof(struct D) == sizeof(struct A) ? 1 : -1];
+
+/* GNU extension.  */
+struct E {
+  struct { char z; };		/* { dg-warning "unnamed structs" } */
+  char e;
+};
+
+
+/* MS extension.  */
+typedef struct A typedef_A;
+struct F {
+  typedef_A;			/* { dg-warning "does not declare anything" } */
+  char f;
+};
+char testF[sizeof(struct F) == sizeof(struct A) ? 1 : -1];
+
+/* __extension__ enables GNU C mode for the duration of the declaration.  */
+__extension__ struct G {
+  struct { char z; };
+  char g;
+};
+char testG[sizeof(struct G) == 2 * sizeof(struct A) ? 1 : -1];
+
+struct H {
+  __extension__ struct { char z; };
+  char h;
+};
+char testH[sizeof(struct H) == 2 * sizeof(struct A) ? 1 : -1];
+
+/* Make sure __extension__ gets turned back off.  */
+struct I {
+  struct { char z; };		/* { dg-warning "unnamed structs" } */
+  char i;
+};
+char testI[sizeof(struct I) == sizeof(struct E) ? 1 : -1];
+