--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp0x/implicit17.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,18 @@
+// PR c++/63540
+// { dg-do compile { target c++11 } }
+
+template <typename T,
+	  typename = decltype(*static_cast<T*>(0) = 0)> int break_it();
+template <typename> int break_it();
+
+struct Base {
+  Base(const Base &);
+  void operator=(Base &&);
+};
+
+struct Derived : Base {
+  using Base::operator=;
+};
+
+int a = break_it<Derived>();
+Derived v(v);