test/std/utilities/function.objects/func.not_fn/not_fn.pass.cpp - llvm-project/libcxx - Git at Google

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 // UNSUPPORTED: c++03, c++11, c++14

 // template <class F> unspecified not_fn(F&& f);

 #include <functional>
 #include <type_traits>
 #include <string>
 #include <cassert>

 #include "test_macros.h"
 #include "type_id.h"
 #include "callable_types.h"

 ///////////////////////////////////////////////////////////////////////////////
 //                        BOOL TEST TYPES
 ///////////////////////////////////////////////////////////////////////////////

 struct EvilBool {
   static int bang_called;

   EvilBool(EvilBool const&) = default;
   EvilBool(EvilBool&&) = default;

   friend EvilBool operator!(EvilBool const& other) {
     ++bang_called;
     return EvilBool{!other.value};
   }

 private:
   friend struct MoveOnlyCallable<EvilBool>;
   friend struct CopyCallable<EvilBool>;
   friend struct NoExceptCallable<EvilBool>;

   constexpr explicit EvilBool(bool x) : value(x) {}
   EvilBool& operator=(EvilBool const& other) = default;

 public:
   bool value;
 };

 int EvilBool::bang_called = 0;

 struct ExplicitBool {
   ExplicitBool(ExplicitBool const&) = default;
   ExplicitBool(ExplicitBool&&) = default;

   constexpr explicit operator bool() const { return value; }

 private:
   friend struct MoveOnlyCallable<ExplicitBool>;
   friend struct CopyCallable<ExplicitBool>;

   constexpr explicit ExplicitBool(bool x) : value(x) {}
   constexpr ExplicitBool& operator=(bool x) {
       value = x;
       return *this;
   }

   bool value;
 };


 struct NoExceptEvilBool {
   NoExceptEvilBool(NoExceptEvilBool const&) = default;
   NoExceptEvilBool(NoExceptEvilBool&&) = default;
   NoExceptEvilBool& operator=(NoExceptEvilBool const& other) = default;

   constexpr explicit NoExceptEvilBool(bool x) : value(x) {}

   friend NoExceptEvilBool operator!(NoExceptEvilBool const& other) noexcept {
     return NoExceptEvilBool{!other.value};
   }

   bool value;
 };


 TEST_CONSTEXPR_CXX20
 bool constructor_tests()
 {
     {
         using T = MoveOnlyCallable<bool>;
         T value(true);
         using RetT = decltype(std::not_fn(std::move(value)));
         static_assert(std::is_move_constructible<RetT>::value, "");
         static_assert(!std::is_copy_constructible<RetT>::value, "");
         static_assert(!std::is_move_assignable<RetT>::value, "");
         static_assert(!std::is_copy_assignable<RetT>::value, "");
         auto ret = std::not_fn(std::move(value));
         // test it was moved from
         assert(value.value == false);
         // test that ret() negates the original value 'true'
         assert(ret() == false);
         assert(ret(0, 0.0, "blah") == false);
         // Move ret and test that it was moved from and that ret2 got the
         // original value.
         auto ret2 = std::move(ret);
         assert(ret() == true);
         assert(ret2() == false);
         assert(ret2(42) == false);
     }
     {
         using T = CopyCallable<bool>;
         T value(false);
         using RetT = decltype(std::not_fn(value));
         static_assert(std::is_move_constructible<RetT>::value, "");
         static_assert(std::is_copy_constructible<RetT>::value, "");
         static_assert(!std::is_move_assignable<RetT>::value, "");
         static_assert(!std::is_copy_assignable<RetT>::value, "");
         auto ret = std::not_fn(value);
         // test that value is unchanged (copied not moved)
         assert(value.value == false);
         // test 'ret' has the original value
         assert(ret() == true);
         assert(ret(42, 100) == true);
         // move from 'ret' and check that 'ret2' has the original value.
         auto ret2 = std::move(ret);
         assert(ret() == false);
         assert(ret2() == true);
         assert(ret2("abc") == true);
         // initialize not_fn with rvalue
         auto ret3 = std::not_fn(std::move(value));
         assert(ret(0) == false);
         assert(ret3(0) == true);
     }
     {
         using T = CopyAssignableWrapper;
         T value(true);
         T value2(false);
         using RetT = decltype(std::not_fn(value));
         static_assert(std::is_move_constructible<RetT>::value, "");
         static_assert(std::is_copy_constructible<RetT>::value, "");
         auto ret = std::not_fn(value);
         assert(ret() == false);
         auto ret2 = std::not_fn(value2);
         assert(ret2() == true);
     }
     {
         using T = MoveAssignableWrapper;
         T value(true);
         T value2(false);
         using RetT = decltype(std::not_fn(std::move(value)));
         static_assert(std::is_move_constructible<RetT>::value, "");
         static_assert(!std::is_copy_constructible<RetT>::value, "");
         static_assert(!std::is_copy_assignable<RetT>::value, "");
         auto ret = std::not_fn(std::move(value));
         assert(ret() == false);
         auto ret2 = std::not_fn(std::move(value2));
         assert(ret2() == true);
     }
     return true;
 }

 void return_type_tests()
 {
     using std::is_same;
     {
         using T = CopyCallable<bool>;
         auto ret = std::not_fn(T{false});
         static_assert(is_same<decltype(ret()), bool>::value, "");
         static_assert(is_same<decltype(ret("abc")), bool>::value, "");
         assert(ret() == true);
     }
     {
         using T = CopyCallable<ExplicitBool>;
         auto ret = std::not_fn(T{true});
         static_assert(is_same<decltype(ret()), bool>::value, "");
         static_assert(is_same<decltype(ret(std::string("abc"))), bool>::value, "");
         assert(ret() == false);
     }
     {
         using T = CopyCallable<EvilBool>;
         auto ret = std::not_fn(T{false});
         static_assert(is_same<decltype(ret()), EvilBool>::value, "");
         EvilBool::bang_called = 0;
         auto value_ret = ret();
         assert(EvilBool::bang_called == 1);
         assert(value_ret.value == true);
         ret();
         assert(EvilBool::bang_called == 2);
     }
 }

 // Other tests only test using objects with call operators. Test various
 // other callable types here.
 TEST_CONSTEXPR_CXX20
 bool other_callable_types_test()
 {
     { // test with function pointer
         auto ret = std::not_fn(returns_true);
         assert(ret() == false);
     }
     { // test with lambda
         auto returns_value = [](bool value) { return value; };
         auto ret = std::not_fn(returns_value);
         assert(ret(true) == false);
         assert(ret(false) == true);
     }
     { // test with pointer to member function
         MemFunCallable mt(true);
         const MemFunCallable mf(false);
         auto ret = std::not_fn(&MemFunCallable::return_value);
         assert(ret(mt) == false);
         assert(ret(mf) == true);
         assert(ret(&mt) == false);
         assert(ret(&mf) == true);
     }
     { // test with pointer to member function
         MemFunCallable mt(true);
         MemFunCallable mf(false);
         auto ret = std::not_fn(&MemFunCallable::return_value_nc);
         assert(ret(mt) == false);
         assert(ret(mf) == true);
         assert(ret(&mt) == false);
         assert(ret(&mf) == true);
     }
     { // test with pointer to member data
         MemFunCallable mt(true);
         const MemFunCallable mf(false);
         auto ret = std::not_fn(&MemFunCallable::value);
         assert(ret(mt) == false);
         assert(ret(mf) == true);
         assert(ret(&mt) == false);
         assert(ret(&mf) == true);
     }
     return true;
 }

 void throws_in_constructor_test()
 {
 #ifndef TEST_HAS_NO_EXCEPTIONS
     struct ThrowsOnCopy {
       ThrowsOnCopy(ThrowsOnCopy const&) {
         throw 42;
       }
       ThrowsOnCopy() = default;
       bool operator()() const {
         assert(false);
 #ifdef TEST_COMPILER_MSVC
         __assume(0);
 #else
         __builtin_unreachable();
 #endif
       }
     };
     {
         ThrowsOnCopy cp;
         try {
             (void)std::not_fn(cp);
             assert(false);
         } catch (int const& value) {
             assert(value == 42);
         }
     }
 #endif
 }

 TEST_CONSTEXPR_CXX20
 bool call_operator_sfinae_test() {
     { // wrong number of arguments
         using T = decltype(std::not_fn(returns_true));
         static_assert(std::is_invocable<T>::value, ""); // callable only with no args
         static_assert(!std::is_invocable<T, bool>::value, "");
     }
     { // violates const correctness (member function pointer)
         using T = decltype(std::not_fn(&MemFunCallable::return_value_nc));
         static_assert(std::is_invocable<T, MemFunCallable&>::value, "");
         static_assert(!std::is_invocable<T, const MemFunCallable&>::value, "");
     }
     { // violates const correctness (call object)
         using Obj = CopyCallable<bool>;
         using NCT = decltype(std::not_fn(Obj{true}));
         using CT = const NCT;
         static_assert(std::is_invocable<NCT>::value, "");
         static_assert(!std::is_invocable<CT>::value, "");
     }
     { // returns bad type with no operator!
         auto fn = [](auto x) { return x; };
         using T = decltype(std::not_fn(fn));
         static_assert(std::is_invocable<T, bool>::value, "");
         static_assert(!std::is_invocable<T, std::string>::value, "");
     }
     return true;
 }

 TEST_CONSTEXPR_CXX20
 bool call_operator_forwarding_test()
 {
     using Fn = ForwardingCallObject;
     Fn::State st;
     auto obj = std::not_fn(Fn{st});
     const auto& c_obj = obj;
     { // test zero args
         obj();
         assert(st.check_call<>(CT_NonConst | CT_LValue));
         std::move(obj)();
         assert(st.check_call<>(CT_NonConst | CT_RValue));
         c_obj();
         assert(st.check_call<>(CT_Const | CT_LValue));
         std::move(c_obj)();
         assert(st.check_call<>(CT_Const | CT_RValue));
     }
     { // test value categories
         int x = 42;
         const int cx = 42;
         obj(x);
         assert(st.check_call<int&>(CT_NonConst | CT_LValue));
         obj(cx);
         assert(st.check_call<const int&>(CT_NonConst | CT_LValue));
         obj(std::move(x));
         assert(st.check_call<int&&>(CT_NonConst | CT_LValue));
         obj(std::move(cx));
         assert(st.check_call<const int&&>(CT_NonConst | CT_LValue));
         obj(42);
         assert(st.check_call<int&&>(CT_NonConst | CT_LValue));
     }
     { // test value categories - rvalue
         int x = 42;
         const int cx = 42;
         std::move(obj)(x);
         assert(st.check_call<int&>(CT_NonConst | CT_RValue));
         std::move(obj)(cx);
         assert(st.check_call<const int&>(CT_NonConst | CT_RValue));
         std::move(obj)(std::move(x));
         assert(st.check_call<int&&>(CT_NonConst | CT_RValue));
         std::move(obj)(std::move(cx));
         assert(st.check_call<const int&&>(CT_NonConst | CT_RValue));
         std::move(obj)(42);
         assert(st.check_call<int&&>(CT_NonConst | CT_RValue));
     }
     { // test value categories - const call
         int x = 42;
         const int cx = 42;
         c_obj(x);
         assert(st.check_call<int&>(CT_Const | CT_LValue));
         c_obj(cx);
         assert(st.check_call<const int&>(CT_Const | CT_LValue));
         c_obj(std::move(x));
         assert(st.check_call<int&&>(CT_Const | CT_LValue));
         c_obj(std::move(cx));
         assert(st.check_call<const int&&>(CT_Const | CT_LValue));
         c_obj(42);
         assert(st.check_call<int&&>(CT_Const | CT_LValue));
     }
     { // test value categories - const call rvalue
         int x = 42;
         const int cx = 42;
         std::move(c_obj)(x);
         assert(st.check_call<int&>(CT_Const | CT_RValue));
         std::move(c_obj)(cx);
         assert(st.check_call<const int&>(CT_Const | CT_RValue));
         std::move(c_obj)(std::move(x));
         assert(st.check_call<int&&>(CT_Const | CT_RValue));
         std::move(c_obj)(std::move(cx));
         assert(st.check_call<const int&&>(CT_Const | CT_RValue));
         std::move(c_obj)(42);
         assert(st.check_call<int&&>(CT_Const | CT_RValue));
     }
     { // test multi arg
         using String = const char *;
         const double y = 3.14;
         String s = "abc";
         obj(42, std::move(y), s, String{"foo"});
         assert((st.check_call<int&&, const double&&, String&, String&&>(CT_NonConst | CT_LValue)));
         std::move(obj)(42, std::move(y), s, String{"foo"});
         assert((st.check_call<int&&, const double&&, String&, String&&>(CT_NonConst | CT_RValue)));
         c_obj(42, std::move(y), s, String{"foo"});
         assert((st.check_call<int&&, const double&&, String&, String&&>(CT_Const  | CT_LValue)));
         std::move(c_obj)(42, std::move(y), s, String{"foo"});
         assert((st.check_call<int&&, const double&&, String&, String&&>(CT_Const  | CT_RValue)));
     }
     return true;
 }

 TEST_CONSTEXPR_CXX20
 bool call_operator_noexcept_test()
 {
     {
         using T = ConstCallable<bool>;
         T value(true);
         auto ret = std::not_fn(value);
         static_assert(!noexcept(ret()), "call should not be noexcept");
         auto const& cret = ret;
         static_assert(!noexcept(cret()), "call should not be noexcept");
     }
     {
         using T = NoExceptCallable<bool>;
         T value(true);
         auto ret = std::not_fn(value);
         LIBCPP_STATIC_ASSERT(noexcept(!std::__invoke(value)), "");
 #if TEST_STD_VER > 14
         static_assert(noexcept(!std::invoke(value)), "");
 #endif
         static_assert(noexcept(ret()), "call should be noexcept");
         auto const& cret = ret;
         static_assert(noexcept(cret()), "call should be noexcept");
     }
     {
         using T = NoExceptCallable<NoExceptEvilBool>;
         T value(true);
         auto ret = std::not_fn(value);
         static_assert(noexcept(ret()), "call should not be noexcept");
         auto const& cret = ret;
         static_assert(noexcept(cret()), "call should not be noexcept");
     }
     {
         using T = NoExceptCallable<EvilBool>;
         T value(true);
         auto ret = std::not_fn(value);
         static_assert(!noexcept(ret()), "call should not be noexcept");
         auto const& cret = ret;
         static_assert(!noexcept(cret()), "call should not be noexcept");
     }
     return true;
 }

 TEST_CONSTEXPR_CXX20
 bool test_lwg2767() {
     // See https://cplusplus.github.io/LWG/lwg-defects.html#2767
     struct Abstract { virtual void f() const = 0; };
     struct Derived : public Abstract { void f() const {} };
     struct F { constexpr bool operator()(Abstract&&) { return false; } };
     {
         Derived d;
         Abstract &a = d;
         bool b = std::not_fn(F{})(std::move(a));
         assert(b);
     }
     return true;
 }

 int main(int, char**)
 {
     constructor_tests();
     return_type_tests();
     other_callable_types_test();
     throws_in_constructor_test();
     call_operator_sfinae_test(); // somewhat of an extension
     call_operator_forwarding_test();
     call_operator_noexcept_test();
     test_lwg2767();

 #if TEST_STD_VER >= 20
     static_assert(constructor_tests());
     static_assert(other_callable_types_test());
     static_assert(call_operator_sfinae_test()); // somewhat of an extension
     static_assert(call_operator_forwarding_test());
     static_assert(call_operator_noexcept_test());
     static_assert(test_lwg2767());
 #endif

     return 0;
 }
	//===----------------------------------------------------------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	// UNSUPPORTED: c++03, c++11, c++14

	// template <class F> unspecified not_fn(F&& f);

	#include <functional>
	#include <type_traits>
	#include <string>
	#include <cassert>

	#include "test_macros.h"
	#include "type_id.h"
	#include "callable_types.h"

	///////////////////////////////////////////////////////////////////////////////
	// BOOL TEST TYPES
	///////////////////////////////////////////////////////////////////////////////

	struct EvilBool {
	static int bang_called;

	EvilBool(EvilBool const&) = default;
	EvilBool(EvilBool&&) = default;

	friend EvilBool operator!(EvilBool const& other) {
	++bang_called;
	return EvilBool{!other.value};
	}

	private:
	friend struct MoveOnlyCallable<EvilBool>;
	friend struct CopyCallable<EvilBool>;
	friend struct NoExceptCallable<EvilBool>;

	constexpr explicit EvilBool(bool x) : value(x) {}
	EvilBool& operator=(EvilBool const& other) = default;

	public:
	bool value;
	};

	int EvilBool::bang_called = 0;

	struct ExplicitBool {
	ExplicitBool(ExplicitBool const&) = default;
	ExplicitBool(ExplicitBool&&) = default;

	constexpr explicit operator bool() const { return value; }

	private:
	friend struct MoveOnlyCallable<ExplicitBool>;
	friend struct CopyCallable<ExplicitBool>;

	constexpr explicit ExplicitBool(bool x) : value(x) {}
	constexpr ExplicitBool& operator=(bool x) {
	value = x;
	return *this;
	}

	bool value;
	};


	struct NoExceptEvilBool {
	NoExceptEvilBool(NoExceptEvilBool const&) = default;
	NoExceptEvilBool(NoExceptEvilBool&&) = default;
	NoExceptEvilBool& operator=(NoExceptEvilBool const& other) = default;

	constexpr explicit NoExceptEvilBool(bool x) : value(x) {}

	friend NoExceptEvilBool operator!(NoExceptEvilBool const& other) noexcept {
	return NoExceptEvilBool{!other.value};
	}

	bool value;
	};



	TEST_CONSTEXPR_CXX20
	bool constructor_tests()
	{
	{
	using T = MoveOnlyCallable<bool>;
	T value(true);
	using RetT = decltype(std::not_fn(std::move(value)));
	static_assert(std::is_move_constructible<RetT>::value, "");
	static_assert(!std::is_copy_constructible<RetT>::value, "");
	static_assert(!std::is_move_assignable<RetT>::value, "");
	static_assert(!std::is_copy_assignable<RetT>::value, "");
	auto ret = std::not_fn(std::move(value));
	// test it was moved from
	assert(value.value == false);
	// test that ret() negates the original value 'true'
	assert(ret() == false);
	assert(ret(0, 0.0, "blah") == false);
	// Move ret and test that it was moved from and that ret2 got the
	// original value.
	auto ret2 = std::move(ret);
	assert(ret() == true);
	assert(ret2() == false);
	assert(ret2(42) == false);
	}
	{
	using T = CopyCallable<bool>;
	T value(false);
	using RetT = decltype(std::not_fn(value));
	static_assert(std::is_move_constructible<RetT>::value, "");
	static_assert(std::is_copy_constructible<RetT>::value, "");
	static_assert(!std::is_move_assignable<RetT>::value, "");
	static_assert(!std::is_copy_assignable<RetT>::value, "");
	auto ret = std::not_fn(value);
	// test that value is unchanged (copied not moved)
	assert(value.value == false);
	// test 'ret' has the original value
	assert(ret() == true);
	assert(ret(42, 100) == true);
	// move from 'ret' and check that 'ret2' has the original value.
	auto ret2 = std::move(ret);
	assert(ret() == false);
	assert(ret2() == true);
	assert(ret2("abc") == true);
	// initialize not_fn with rvalue
	auto ret3 = std::not_fn(std::move(value));
	assert(ret(0) == false);
	assert(ret3(0) == true);
	}
	{
	using T = CopyAssignableWrapper;
	T value(true);
	T value2(false);
	using RetT = decltype(std::not_fn(value));
	static_assert(std::is_move_constructible<RetT>::value, "");
	static_assert(std::is_copy_constructible<RetT>::value, "");
	auto ret = std::not_fn(value);
	assert(ret() == false);
	auto ret2 = std::not_fn(value2);
	assert(ret2() == true);
	}
	{
	using T = MoveAssignableWrapper;
	T value(true);
	T value2(false);
	using RetT = decltype(std::not_fn(std::move(value)));
	static_assert(std::is_move_constructible<RetT>::value, "");
	static_assert(!std::is_copy_constructible<RetT>::value, "");
	static_assert(!std::is_copy_assignable<RetT>::value, "");
	auto ret = std::not_fn(std::move(value));
	assert(ret() == false);
	auto ret2 = std::not_fn(std::move(value2));
	assert(ret2() == true);
	}
	return true;
	}

	void return_type_tests()
	{
	using std::is_same;
	{
	using T = CopyCallable<bool>;
	auto ret = std::not_fn(T{false});
	static_assert(is_same<decltype(ret()), bool>::value, "");
	static_assert(is_same<decltype(ret("abc")), bool>::value, "");
	assert(ret() == true);
	}
	{
	using T = CopyCallable<ExplicitBool>;
	auto ret = std::not_fn(T{true});
	static_assert(is_same<decltype(ret()), bool>::value, "");
	static_assert(is_same<decltype(ret(std::string("abc"))), bool>::value, "");
	assert(ret() == false);
	}
	{
	using T = CopyCallable<EvilBool>;
	auto ret = std::not_fn(T{false});
	static_assert(is_same<decltype(ret()), EvilBool>::value, "");
	EvilBool::bang_called = 0;
	auto value_ret = ret();
	assert(EvilBool::bang_called == 1);
	assert(value_ret.value == true);
	ret();
	assert(EvilBool::bang_called == 2);
	}
	}

	// Other tests only test using objects with call operators. Test various
	// other callable types here.
	TEST_CONSTEXPR_CXX20
	bool other_callable_types_test()
	{
	{ // test with function pointer
	auto ret = std::not_fn(returns_true);
	assert(ret() == false);
	}
	{ // test with lambda
	auto returns_value = [](bool value) { return value; };
	auto ret = std::not_fn(returns_value);
	assert(ret(true) == false);
	assert(ret(false) == true);
	}
	{ // test with pointer to member function
	MemFunCallable mt(true);
	const MemFunCallable mf(false);
	auto ret = std::not_fn(&MemFunCallable::return_value);
	assert(ret(mt) == false);
	assert(ret(mf) == true);
	assert(ret(&mt) == false);
	assert(ret(&mf) == true);
	}
	{ // test with pointer to member function
	MemFunCallable mt(true);
	MemFunCallable mf(false);
	auto ret = std::not_fn(&MemFunCallable::return_value_nc);
	assert(ret(mt) == false);
	assert(ret(mf) == true);
	assert(ret(&mt) == false);
	assert(ret(&mf) == true);
	}
	{ // test with pointer to member data
	MemFunCallable mt(true);
	const MemFunCallable mf(false);
	auto ret = std::not_fn(&MemFunCallable::value);
	assert(ret(mt) == false);
	assert(ret(mf) == true);
	assert(ret(&mt) == false);
	assert(ret(&mf) == true);
	}
	return true;
	}

	void throws_in_constructor_test()
	{
	#ifndef TEST_HAS_NO_EXCEPTIONS
	struct ThrowsOnCopy {
	ThrowsOnCopy(ThrowsOnCopy const&) {
	throw 42;
	}
	ThrowsOnCopy() = default;
	bool operator()() const {
	assert(false);
	#ifdef TEST_COMPILER_MSVC
	__assume(0);
	#else
	__builtin_unreachable();
	#endif
	}
	};
	{
	ThrowsOnCopy cp;
	try {
	(void)std::not_fn(cp);
	assert(false);
	} catch (int const& value) {
	assert(value == 42);
	}
	}
	#endif
	}

	TEST_CONSTEXPR_CXX20
	bool call_operator_sfinae_test() {
	{ // wrong number of arguments
	using T = decltype(std::not_fn(returns_true));
	static_assert(std::is_invocable<T>::value, ""); // callable only with no args
	static_assert(!std::is_invocable<T, bool>::value, "");
	}
	{ // violates const correctness (member function pointer)
	using T = decltype(std::not_fn(&MemFunCallable::return_value_nc));
	static_assert(std::is_invocable<T, MemFunCallable&>::value, "");
	static_assert(!std::is_invocable<T, const MemFunCallable&>::value, "");
	}
	{ // violates const correctness (call object)
	using Obj = CopyCallable<bool>;
	using NCT = decltype(std::not_fn(Obj{true}));
	using CT = const NCT;
	static_assert(std::is_invocable<NCT>::value, "");
	static_assert(!std::is_invocable<CT>::value, "");
	}
	{ // returns bad type with no operator!
	auto fn = [](auto x) { return x; };
	using T = decltype(std::not_fn(fn));
	static_assert(std::is_invocable<T, bool>::value, "");
	static_assert(!std::is_invocable<T, std::string>::value, "");
	}
	return true;
	}

	TEST_CONSTEXPR_CXX20
	bool call_operator_forwarding_test()
	{
	using Fn = ForwardingCallObject;
	Fn::State st;
	auto obj = std::not_fn(Fn{st});
	const auto& c_obj = obj;
	{ // test zero args
	obj();
	assert(st.check_call<>(CT_NonConst \| CT_LValue));
	std::move(obj)();
	assert(st.check_call<>(CT_NonConst \| CT_RValue));
	c_obj();
	assert(st.check_call<>(CT_Const \| CT_LValue));
	std::move(c_obj)();
	assert(st.check_call<>(CT_Const \| CT_RValue));
	}
	{ // test value categories
	int x = 42;
	const int cx = 42;
	obj(x);
	assert(st.check_call<int&>(CT_NonConst \| CT_LValue));
	obj(cx);
	assert(st.check_call<const int&>(CT_NonConst \| CT_LValue));
	obj(std::move(x));
	assert(st.check_call<int&&>(CT_NonConst \| CT_LValue));
	obj(std::move(cx));
	assert(st.check_call<const int&&>(CT_NonConst \| CT_LValue));
	obj(42);
	assert(st.check_call<int&&>(CT_NonConst \| CT_LValue));
	}
	{ // test value categories - rvalue
	int x = 42;
	const int cx = 42;
	std::move(obj)(x);
	assert(st.check_call<int&>(CT_NonConst \| CT_RValue));
	std::move(obj)(cx);
	assert(st.check_call<const int&>(CT_NonConst \| CT_RValue));
	std::move(obj)(std::move(x));
	assert(st.check_call<int&&>(CT_NonConst \| CT_RValue));
	std::move(obj)(std::move(cx));
	assert(st.check_call<const int&&>(CT_NonConst \| CT_RValue));
	std::move(obj)(42);
	assert(st.check_call<int&&>(CT_NonConst \| CT_RValue));
	}
	{ // test value categories - const call
	int x = 42;
	const int cx = 42;
	c_obj(x);
	assert(st.check_call<int&>(CT_Const \| CT_LValue));
	c_obj(cx);
	assert(st.check_call<const int&>(CT_Const \| CT_LValue));
	c_obj(std::move(x));
	assert(st.check_call<int&&>(CT_Const \| CT_LValue));
	c_obj(std::move(cx));
	assert(st.check_call<const int&&>(CT_Const \| CT_LValue));
	c_obj(42);
	assert(st.check_call<int&&>(CT_Const \| CT_LValue));
	}
	{ // test value categories - const call rvalue
	int x = 42;
	const int cx = 42;
	std::move(c_obj)(x);
	assert(st.check_call<int&>(CT_Const \| CT_RValue));
	std::move(c_obj)(cx);
	assert(st.check_call<const int&>(CT_Const \| CT_RValue));
	std::move(c_obj)(std::move(x));
	assert(st.check_call<int&&>(CT_Const \| CT_RValue));
	std::move(c_obj)(std::move(cx));
	assert(st.check_call<const int&&>(CT_Const \| CT_RValue));
	std::move(c_obj)(42);
	assert(st.check_call<int&&>(CT_Const \| CT_RValue));
	}
	{ // test multi arg
	using String = const char *;
	const double y = 3.14;
	String s = "abc";
	obj(42, std::move(y), s, String{"foo"});
	assert((st.check_call<int&&, const double&&, String&, String&&>(CT_NonConst \| CT_LValue)));
	std::move(obj)(42, std::move(y), s, String{"foo"});
	assert((st.check_call<int&&, const double&&, String&, String&&>(CT_NonConst \| CT_RValue)));
	c_obj(42, std::move(y), s, String{"foo"});
	assert((st.check_call<int&&, const double&&, String&, String&&>(CT_Const \| CT_LValue)));
	std::move(c_obj)(42, std::move(y), s, String{"foo"});
	assert((st.check_call<int&&, const double&&, String&, String&&>(CT_Const \| CT_RValue)));
	}
	return true;
	}

	TEST_CONSTEXPR_CXX20
	bool call_operator_noexcept_test()
	{
	{
	using T = ConstCallable<bool>;
	T value(true);
	auto ret = std::not_fn(value);
	static_assert(!noexcept(ret()), "call should not be noexcept");
	auto const& cret = ret;
	static_assert(!noexcept(cret()), "call should not be noexcept");
	}
	{
	using T = NoExceptCallable<bool>;
	T value(true);
	auto ret = std::not_fn(value);
	LIBCPP_STATIC_ASSERT(noexcept(!std::__invoke(value)), "");
	#if TEST_STD_VER > 14
	static_assert(noexcept(!std::invoke(value)), "");
	#endif
	static_assert(noexcept(ret()), "call should be noexcept");
	auto const& cret = ret;
	static_assert(noexcept(cret()), "call should be noexcept");
	}
	{
	using T = NoExceptCallable<NoExceptEvilBool>;
	T value(true);
	auto ret = std::not_fn(value);
	static_assert(noexcept(ret()), "call should not be noexcept");
	auto const& cret = ret;
	static_assert(noexcept(cret()), "call should not be noexcept");
	}
	{
	using T = NoExceptCallable<EvilBool>;
	T value(true);
	auto ret = std::not_fn(value);
	static_assert(!noexcept(ret()), "call should not be noexcept");
	auto const& cret = ret;
	static_assert(!noexcept(cret()), "call should not be noexcept");
	}
	return true;
	}

	TEST_CONSTEXPR_CXX20
	bool test_lwg2767() {
	// See https://cplusplus.github.io/LWG/lwg-defects.html#2767
	struct Abstract { virtual void f() const = 0; };
	struct Derived : public Abstract { void f() const {} };
	struct F { constexpr bool operator()(Abstract&&) { return false; } };
	{
	Derived d;
	Abstract &a = d;
	bool b = std::not_fn(F{})(std::move(a));
	assert(b);
	}
	return true;
	}

	int main(int, char**)
	{
	constructor_tests();
	return_type_tests();
	other_callable_types_test();
	throws_in_constructor_test();
	call_operator_sfinae_test(); // somewhat of an extension
	call_operator_forwarding_test();
	call_operator_noexcept_test();
	test_lwg2767();

	#if TEST_STD_VER >= 20
	static_assert(constructor_tests());
	static_assert(other_callable_types_test());
	static_assert(call_operator_sfinae_test()); // somewhat of an extension
	static_assert(call_operator_forwarding_test());
	static_assert(call_operator_noexcept_test());
	static_assert(test_lwg2767());
	#endif

	return 0;
	}