llvm/libcxx/test/std/utilities/meta/meta.unary.prop.query/void_t.pass.cpp

//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// type_traits

// void_t

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

#include <type_traits>

#include "test_macros.h"

template <class T>
void test1()
{
    ASSERT_SAME_TYPE(void, std::void_t<T>);
    ASSERT_SAME_TYPE(void, std::void_t<const T>);
    ASSERT_SAME_TYPE(void, std::void_t<volatile T>);
    ASSERT_SAME_TYPE(void, std::void_t<const volatile T>);
}

template <class T, class U>
void test2()
{
    ASSERT_SAME_TYPE(void, std::void_t<T, U>);
    ASSERT_SAME_TYPE(void, std::void_t<const T, U>);
    ASSERT_SAME_TYPE(void, std::void_t<volatile T, U>);
    ASSERT_SAME_TYPE(void, std::void_t<const volatile T, U>);

    ASSERT_SAME_TYPE(void, std::void_t<U, T>);
    ASSERT_SAME_TYPE(void, std::void_t<U, const T>);
    ASSERT_SAME_TYPE(void, std::void_t<U, volatile T>);
    ASSERT_SAME_TYPE(void, std::void_t<U, const volatile T>);

    ASSERT_SAME_TYPE(void, std::void_t<T, const U>);
    ASSERT_SAME_TYPE(void, std::void_t<const T, const U>);
    ASSERT_SAME_TYPE(void, std::void_t<volatile T, const U>);
    ASSERT_SAME_TYPE(void, std::void_t<const volatile T, const U>);
}

class Class
{
public:
    ~Class();
};

int main(int, char**)
{
    ASSERT_SAME_TYPE(void, std::void_t<>);

    test1<void>();
    test1<int>();
    test1<double>();
    test1<int&>();
    test1<Class>();
    test1<Class[]>();
    test1<Class[5]>();

    test2<void, int>();
    test2<double, int>();
    test2<int&, int>();
    test2<Class&, bool>();
    test2<void *, int&>();

    ASSERT_SAME_TYPE(void, std::void_t<int, double const &, Class, volatile int[], void>);

  return 0;
}