--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/old-style-prom-2.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,14 @@
+/* Test for prototype followed by old-style definition, as in
+   dremf-type-compat-2.c but with a non-built-in function.  */
+/* { dg-do compile } */
+/* { dg-options "-pedantic" } */
+
+float f (float, float); /* { dg-warning "prototype declaration" } */
+
+float
+f (x, y)
+     float x; /* { dg-warning "promoted argument 'x' doesn't match prototype" } */
+     float y; /* { dg-warning "promoted argument 'y' doesn't match prototype" } */
+{
+  return x + y;
+}