--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/nested-redef-1.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,44 @@
+/* Test diagnosis of nested tag redefinitions.  */
+/* Origin: Joseph Myers <jsm@polyomino.org.uk> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+struct s0 {
+  struct s0 { int a; } x; /* { dg-error "nested redefinition of 'struct s0'" } */
+};
+
+struct s1 {
+  const struct s1 { int b; } x; /* { dg-error "nested redefinition of 'struct s1'" } */
+};
+
+struct s2 {
+  struct s2 { int c; } *x; /* { dg-error "nested redefinition of 'struct s2'" } */
+};
+
+struct s3 {
+  struct s4 {
+    struct s5 {
+      struct s3 { int a; } **x; /* { dg-error "nested redefinition of 'struct s3'" } */
+    } y;
+  } z;
+};
+
+struct s6;
+struct s6 { struct s6 *p; };
+
+union u0 {
+  union u0 { int c; } *x; /* { dg-error "nested redefinition of 'union u0'" } */
+};
+
+enum e0 {
+  E0 = sizeof(enum e0 { E1 }) /* { dg-error "nested redefinition of 'enum e0'" } */
+};
+
+enum e1 {
+  E2 = sizeof(enum e2 { E2 }), /* { dg-error "redeclaration of enumerator 'E2'" } */
+  /* { dg-message "note: previous definition" "previous E2" { target *-*-* } .-1 } */
+  E3
+};
+
+enum e3;
+enum e3 { E4 = 0 };