--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp0x/implicit16.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,37 @@
+// PR c++/89381
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+struct base
+{
+  base() { }
+  base(const base&) { }
+  base(base&&) { }
+  base& operator=(const base&) { return *this; }
+  base& operator=(base&&) { return *this; }
+};
+
+struct foo : base<int>
+{
+    using base<int>::base;
+    using base<int>::operator=;
+};
+
+//using workaround = decltype(foo{*static_cast<foo const*>(0)});
+
+struct bar
+{
+    bar& operator=(foo ve)
+    {
+        value = ve;
+        return *this;
+    }
+
+    foo value;
+};
+
+int main()
+{
+    foo a;
+    foo b{a};
+}