Test more not_fns for emptiness

Comment: #86133 (comment)

Author: JMazurkiewicz

libcxx/test/libcxx/utilities/function.objects/func.not.fn/not_fn.nttp.compile.pass.cpp

@@ -17,11 +17,27 @@
 
 struct NonEmptyFunctionObject {
   bool val = true;
-  bool operator()() const; // not defined
+  bool operator()() const;
+};
+
+bool func();
+
+struct SomeClass {
+  bool member_object;
+  bool member_function();
 };
 
 using ResultWithEmptyFuncObject = decltype(std::not_fn<std::false_type{}>());
 static_assert(std::is_empty_v<ResultWithEmptyFuncObject>);
 
 using ResultWithNotEmptyFuncObject = decltype(std::not_fn<NonEmptyFunctionObject{}>());
 static_assert(std::is_empty_v<ResultWithNotEmptyFuncObject>);
+
+using ResultWithFunctionPointer = decltype(std::not_fn<&func>());
+static_assert(std::is_empty_v<ResultWithFunctionPointer>);
+
+using ResultWithMemberObjectPointer = decltype(std::not_fn<&SomeClass::member_object>());
+static_assert(std::is_empty_v<ResultWithMemberObjectPointer>);
+
+using ResultWithMemberFunctionPointer = decltype(std::not_fn<&SomeClass::member_function>());
+static_assert(std::is_empty_v<ResultWithMemberFunctionPointer>);