new file mode 100644
@@ -0,0 +1,24 @@
+// PR c++/81339
+// { dg-do compile { target c++11 } }
+
+struct true_type { static const bool value = true; };
+struct false_type { static const bool value = false; };
+
+template <typename T>
+struct IsDefaultConstructibleT
+{
+ // using T here (instead of U) should be an error
+ template <typename U, typename = decltype(T())> // { dg-error "deleted" }
+ static true_type test(void*);
+
+ template <typename U>
+ static false_type test(...);
+
+ static constexpr bool value = decltype(test<T>(nullptr))::value;
+};
+
+struct S {
+ S() = delete;
+};
+
+static_assert( IsDefaultConstructibleT<S>::value, "" ); // { dg-error "assertion failed" }