--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/pr68533.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,68 @@
+/* PR c/68533 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+struct T { int t; };
+
+void
+f1 (
+  struct S *	/* { dg-warning "declared inside parameter list will not be visible outside of this definition or declaration" } */
+  x,
+  struct T *
+  y
+   )
+{
+  y->t = 4;
+}
+
+void
+f2 (
+  struct {int s;} * /* { dg-warning "anonymous struct declared inside parameter list will not be visible outside of this definition or declaration" } */
+  x,
+  struct T *
+  y
+   )
+{
+  y->t = 5;
+}
+
+void
+f3 (
+  const void	/* { dg-error "'void' as only parameter may not be qualified" } */
+   )
+{
+}
+
+void
+f4 (
+   void,	/* { dg-error "'void' must be the only parameter" } */
+   ...
+   )
+{
+}
+
+void
+f5 (
+   int
+   x;		/* { dg-error "parameter 'x' has just a forward declaration" } */
+   int y
+   )
+{
+}
+
+void
+f6 (
+   int
+   x,
+   void	/* { dg-error "'void' must be the only parameter" } */
+   )
+{
+}
+
+void
+f7 (
+   void,	/* { dg-error "'void' must be the only parameter" } */
+   int y
+   )
+{
+}