--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const11.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,16 @@
+// PR c++/91264
+// { dg-do compile { target c++14 } }
+
+struct S {
+    int a = 1;
+    int * ptr = &a;
+};
+
+constexpr bool f() {
+    auto const s = S{}; // { dg-message "originally declared" }
+    *s.ptr = 2; // { dg-error "modifying a const object" }
+    return s.a == 2;
+}
+
+static_assert(f(), ""); // { dg-error "non-constant condition" }
+// { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }