--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/comma3.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,27 @@
+// PR c++/91338 - P1161R3: Deprecate a[b,c].
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wcomma-subscript" }
+
+struct S {
+  int operator,(int) { return 42; }
+};
+
+void
+fn (int *a, int b, int c)
+{
+  a[b,c]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
+  a[(b,c)];
+
+  a[(void) b, c]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
+  a[((void) b, c)];
+
+  a[(void) b, (void) c, (void) b, b]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
+  a[((void) b, (void) c, (void) b, b)];
+
+  a[S(), 10]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
+  a[(S(), 10)];
+
+  a[int{(1,2)}];
+  a[int{(1,2)}, int{}]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
+  a[(int{(1,2)}, int{})];
+}