new file mode 100644
@@ -0,0 +1,22 @@
+// { dg-do compile { target c++11 } }
+
+#include <type_traits>
+
+class S {
+ operator int();
+ friend void g(); // #1
+};
+
+void
+g()
+{
+ int i = 0;
+ S s;
+ i = s; // this works, because we're inside a friend.
+
+ // But the traits are evaluated in "a context unrelated to either type".
+ static_assert( ! std::is_assignable<int&, S>::value, "unfriendly");
+#if __cplusplus >= 201703L
+ static_assert( ! std::is_assignable_v<int&, S>, "unfriendly");
+#endif
+}