| //===----------------------------------------------------------------------===// |
| // |
| // 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, c++17, c++20 |
| |
| // <utility> |
| |
| // template <class T1, class T2> struct pair |
| // template <class U1, class U2> |
| // constexpr explicit(see below) pair(pair<U1, U2>& p); |
| |
| #include <cassert> |
| #include <utility> |
| |
| #include "copy_move_types.h" |
| #include "test_macros.h" |
| |
| // Constraints: |
| // is_constructible_v<T1, decltype(get<0>(FWD(p)))> is true and |
| // is_constructible_v<T2, decltype(get<1>(FWD(p)))> is true. |
| struct X {}; |
| struct Y {}; |
| struct NotConvertibleToXorY {}; |
| |
| // clang-format off |
| static_assert( std::is_constructible_v<std::pair<X, Y>, std::pair<X, Y>&>); |
| static_assert(!std::is_constructible_v<std::pair<X, Y>, std::pair<NotConvertibleToXorY, Y>&>); |
| static_assert(!std::is_constructible_v<std::pair<X, Y>, std::pair<X, NotConvertibleToXorY>&>); |
| static_assert(!std::is_constructible_v<std::pair<X, Y>, std::pair<NotConvertibleToXorY, NotConvertibleToXorY>&>); |
| |
| // The expression inside explicit is equivalent to: |
| // !is_convertible_v<decltype(get<0>(FWD(p))), first_type> || |
| // !is_convertible_v<decltype(get<1>(FWD(p))), second_type>. |
| static_assert( std::is_convertible_v<std::pair<X, Y>&, std::pair<ConvertibleFrom<X>, ConvertibleFrom<Y>>>); |
| static_assert(!std::is_convertible_v<std::pair<X, Y>&, std::pair<ConvertibleFrom<X>, ExplicitConstructibleFrom<Y>>>); |
| static_assert(!std::is_convertible_v<std::pair<X, Y>&, std::pair<ExplicitConstructibleFrom<X>, ConvertibleFrom<Y>>>); |
| static_assert(!std::is_convertible_v<std::pair<X, Y>&, std::pair<ExplicitConstructibleFrom<X>, ExplicitConstructibleFrom<Y>>>); |
| // clang-format on |
| |
| constexpr bool test() { |
| // use case in zip. Init pair<T&, U&> from pair<T, U>& |
| { |
| std::pair<int, int> p1{1, 2}; |
| std::pair<int&, int&> p2{p1}; |
| assert(&(p2.first) == &(p1.first)); |
| assert(&(p2.second) == &(p1.second)); |
| } |
| |
| // test implicit conversions. |
| { |
| std::pair<MutableCopy, int> p1{1, 2}; |
| std::pair<ConvertibleFrom<MutableCopy>, ConvertibleFrom<int>> p2 = p1; |
| assert(p2.first.v.val == 1); |
| assert(p2.second.v == 2); |
| } |
| |
| // test explicit conversions. |
| { |
| std::pair<MutableCopy, int> p1{1, 2}; |
| std::pair<ExplicitConstructibleFrom<MutableCopy>, ExplicitConstructibleFrom<int>> p2{p1}; |
| assert(p2.first.v.val == 1); |
| assert(p2.second.v == 2); |
| } |
| |
| // test correct constructors of underlying types are called |
| { |
| std::pair<TracedCopyMove, TracedCopyMove> p1{}; |
| std::pair<ConvertibleFrom<TracedCopyMove>, ConvertibleFrom<TracedCopyMove>> p2{p1}; |
| assert(nonConstCopyCtrCalled(p2.first.v)); |
| assert(nonConstCopyCtrCalled(p2.second.v)); |
| } |
| |
| return true; |
| } |
| |
| int main(int, char**) { |
| test(); |
| static_assert(test()); |
| return 0; |
| } |