| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
| // UNSUPPORTED: libcpp-no-concepts |
| |
| // template<class T> |
| // struct indirectly_readable_traits; |
| |
| #include <iterator> |
| |
| #include <concepts> |
| #include <memory> |
| #include <optional> |
| #include <string> |
| #include <vector> |
| |
| // `value_type` and `element_type` member aliases aren't actually used to declare anytihng, so GCC |
| // thinks they're completely unused. |
| #pragma GCC diagnostic ignored "-Wunused-local-typedefs" |
| |
| // clang-format off |
| template <class T> |
| concept check_has_value_type = requires { |
| typename std::indirectly_readable_traits<T>::value_type; |
| }; |
| |
| template <class T, class Expected> |
| concept check_value_type_matches = |
| check_has_value_type<T> && |
| std::same_as<typename std::indirectly_readable_traits<T>::value_type, Expected>; |
| // clang-format on |
| |
| template <class T> |
| constexpr bool check_pointer() { |
| constexpr bool result = check_value_type_matches<T*, T>; |
| static_assert(check_value_type_matches<T const*, T> == result); |
| static_assert(check_value_type_matches<T volatile*, T> == result); |
| static_assert(check_value_type_matches<T const volatile*, T> == result); |
| |
| static_assert(check_value_type_matches<T* const, T> == result); |
| static_assert(check_value_type_matches<T const* const, T> == result); |
| static_assert(check_value_type_matches<T volatile* const, T> == result); |
| static_assert(check_value_type_matches<T const volatile* const, T> == result); |
| |
| return result; |
| } |
| |
| static_assert(!check_pointer<void>()); |
| static_assert(check_pointer<int>()); |
| static_assert(check_pointer<long>()); |
| static_assert(check_pointer<double>()); |
| static_assert(check_pointer<double*>()); |
| |
| struct S {}; |
| static_assert(check_pointer<S>()); |
| |
| template <class T> |
| constexpr bool check_array() { |
| constexpr bool result = check_value_type_matches<T[], T>; |
| static_assert(check_value_type_matches<T const[], T> == result); |
| static_assert(check_value_type_matches<T volatile[], T> == result); |
| static_assert(check_value_type_matches<T const volatile[], T> == result); |
| static_assert(check_value_type_matches<T[10], T> == result); |
| static_assert(check_value_type_matches<T const[10], T> == result); |
| static_assert(check_value_type_matches<T volatile[10], T> == result); |
| static_assert(check_value_type_matches<T const volatile[10], T> == result); |
| return result; |
| } |
| |
| static_assert(check_array<int>()); |
| static_assert(check_array<long>()); |
| static_assert(check_array<double>()); |
| static_assert(check_array<double*>()); |
| static_assert(check_array<S>()); |
| |
| template <class T, class Expected> |
| constexpr bool check_explicit_member() { |
| constexpr bool result = check_value_type_matches<T, Expected>; |
| static_assert(check_value_type_matches<T const, Expected> == result); |
| return result; |
| } |
| |
| struct has_value_type { |
| using value_type = int; |
| }; |
| static_assert(check_explicit_member<has_value_type, int>()); |
| static_assert(check_explicit_member<std::vector<int>::iterator, int>()); |
| |
| struct has_element_type { |
| using element_type = S; |
| }; |
| static_assert(check_explicit_member<has_element_type, S>()); |
| |
| struct has_same_value_and_element_type { |
| using value_type = int; |
| using element_type = int; |
| }; |
| static_assert(check_explicit_member<has_same_value_and_element_type, int>()); |
| static_assert(check_explicit_member<std::shared_ptr<long>, long>()); |
| static_assert(check_explicit_member<std::shared_ptr<long const>, long>()); |
| |
| // clang-format off |
| template<class T, class U> |
| requires std::same_as<std::remove_cv_t<T>, std::remove_cv_t<U> > |
| struct possibly_different_cv_qualifiers { |
| using value_type = T; |
| using element_type = U; |
| }; |
| // clang-format on |
| |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int, int>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int, int const>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int, int volatile>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int, int const volatile>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const, int>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const, int const>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const, int volatile>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const, int const volatile>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int volatile, int>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int volatile, int const>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int volatile, int volatile>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int volatile, int const volatile>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const volatile, int>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const volatile, int const>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const volatile, int volatile>, int>()); |
| static_assert(check_explicit_member<possibly_different_cv_qualifiers<int const volatile, int const volatile>, int>()); |
| |
| struct S2 {}; |
| namespace std { |
| template <> |
| struct indirectly_readable_traits<S2> { |
| using value_type = int; |
| }; |
| } // namespace std |
| static_assert(check_value_type_matches<S2, int>); |
| static_assert(check_value_type_matches<std::vector<int>, int>); |
| static_assert(check_value_type_matches<std::vector<int>::iterator, int>); |
| static_assert(check_value_type_matches<std::vector<int>::const_iterator, int>); |
| static_assert(check_value_type_matches<std::istream_iterator<int>, int>); |
| static_assert(check_value_type_matches<std::istreambuf_iterator<char>, char>); |
| static_assert(check_value_type_matches<std::optional<int>, int>); |
| |
| template <class T> |
| constexpr bool check_ref() { |
| struct ref_value { |
| using value_type = T&; |
| }; |
| constexpr bool result = check_has_value_type<ref_value>; |
| |
| struct ref_element { |
| using element_type = T&; |
| }; |
| static_assert(check_has_value_type<ref_element> == result); |
| |
| return result; |
| } |
| |
| static_assert(!check_ref<int>()); |
| static_assert(!check_ref<S>()); |
| static_assert(!check_ref<std::shared_ptr<long> >()); |
| |
| static_assert(!check_has_value_type<void>); |
| static_assert(!check_has_value_type<std::nullptr_t>); |
| static_assert(!check_has_value_type<int>); |
| static_assert(!check_has_value_type<S>); |
| |
| struct has_different_value_and_element_type { |
| using value_type = int; |
| using element_type = long; |
| }; |
| static_assert(!check_has_value_type<has_different_value_and_element_type>); |
| |
| struct void_value { |
| using value_type = void; |
| }; |
| static_assert(!check_has_value_type<void_value>); |
| |
| struct void_element { |
| using element_type = void; |
| }; |
| static_assert(!check_has_value_type<void_element>); |