sources/cxx-stl/llvm-libc++/test/std/utilities/meta/meta.trans/meta.trans.ref/add_lvalue_ref.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// type_traits

// add_lvalue_reference
// If T names a referenceable type then the member typedef type
//    shall name T&; otherwise, type shall name T.

#include <type_traits>
#include "test_macros.h"

template <class T, class U>
void test_add_lvalue_reference()
{
    static_assert((std::is_same<typename std::add_lvalue_reference<T>::type, U>::value), "");
#if TEST_STD_VER > 11
    static_assert((std::is_same<std::add_lvalue_reference_t<T>, U>::value), "");
#endif
}

template <class F>
void test_function0()
{
    static_assert((std::is_same<typename std::add_lvalue_reference<F>::type, F&>::value), "");
#if TEST_STD_VER > 11
    static_assert((std::is_same<std::add_lvalue_reference_t<F>, F&>::value), "");
#endif
}

template <class F>
void test_function1()
{
    static_assert((std::is_same<typename std::add_lvalue_reference<F>::type, F>::value), "");
#if TEST_STD_VER > 11
    static_assert((std::is_same<std::add_lvalue_reference_t<F>, F>::value), "");
#endif
}

struct Foo {};

int main()
{
    test_add_lvalue_reference<void, void>();
    test_add_lvalue_reference<int, int&>();
    test_add_lvalue_reference<int[3], int(&)[3]>();
    test_add_lvalue_reference<int&, int&>();
    test_add_lvalue_reference<const int&, const int&>();
    test_add_lvalue_reference<int*, int*&>();
    test_add_lvalue_reference<const int*, const int*&>();
    test_add_lvalue_reference<Foo, Foo&>();

//  LWG 2101 specifically talks about add_lvalue_reference and functions.
//  The term of art is "a referenceable type", which a cv- or ref-qualified function is not.
    test_function0<void()>();
#if TEST_STD_VER >= 11
    test_function1<void() const>();
    test_function1<void() &>();
    test_function1<void() &&>();
    test_function1<void() const &>();
    test_function1<void() const &&>();
#endif

//  But a cv- or ref-qualified member function *is* "a referenceable type"
    test_function0<void (Foo::*)()>();
#if TEST_STD_VER >= 11
    test_function0<void (Foo::*)() const>();
    test_function0<void (Foo::*)() &>();
    test_function0<void (Foo::*)() &&>();
    test_function0<void (Foo::*)() const &>();
    test_function0<void (Foo::*)() const &&>();
#endif
}