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[libc++] P2255R2: Add deleted pair constructor overloads #164214

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[libc++] P2255R2: Add deleted pair constructor overloads #164214

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2 changes: 1 addition & 1 deletion libcxx/docs/Status/Cxx23Papers.csv
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@
"`P0627R6 <https://wg21.link/P0627R6>`__","Function to mark unreachable code","2022-02 (Virtual)","|Complete|","15","`#105175 <https://github.com/llvm/llvm-project/issues/105175>`__",""
"`P1206R7 <https://wg21.link/P1206R7>`__","``ranges::to``: A function to convert any range to a container","2022-02 (Virtual)","|Complete|","17","`#105176 <https://github.com/llvm/llvm-project/issues/105176>`__",""
"`P1413R3 <https://wg21.link/P1413R3>`__","Deprecate ``std::aligned_storage`` and ``std::aligned_union``","2022-02 (Virtual)","|Complete|","","`#105177 <https://github.com/llvm/llvm-project/issues/105177>`__","``std::aligned_storage_t`` and ``std::aligned_union_t`` are marked deprecated, but clang doesn't issue a diagnostic for deprecated using template declarations."
"`P2255R2 <https://wg21.link/P2255R2>`__","A type trait to detect reference binding to temporary","2022-02 (Virtual)","|Partial|","","`#105180 <https://github.com/llvm/llvm-project/issues/105180>`__","Implemented the type traits only."
"`P2255R2 <https://wg21.link/P2255R2>`__","A type trait to detect reference binding to temporary","2022-02 (Virtual)","|Partial|","","`#105180 <https://github.com/llvm/llvm-project/issues/105180>`__","Implemented the type traits and changes to ``std::pair`` only."
"`P2273R3 <https://wg21.link/P2273R3>`__","Making ``std::unique_ptr`` constexpr","2022-02 (Virtual)","|Complete|","16","`#105182 <https://github.com/llvm/llvm-project/issues/105182>`__",""
"`P2387R3 <https://wg21.link/P2387R3>`__","Pipe support for user-defined range adaptors","2022-02 (Virtual)","|Complete|","19","`#105183 <https://github.com/llvm/llvm-project/issues/105183>`__",""
"`P2440R1 <https://wg21.link/P2440R1>`__","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","2022-02 (Virtual)","|Partial|","","`#105184 <https://github.com/llvm/llvm-project/issues/105184>`__","Only ``ranges::iota`` is implemented."
Expand Down
77 changes: 69 additions & 8 deletions libcxx/include/__utility/pair.h
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
#include <__config>
#include <__cstddef/size_t.h>
#include <__fwd/array.h>
#include <__fwd/complex.h>
#include <__fwd/pair.h>
#include <__fwd/tuple.h>
#include <__tuple/tuple_like_no_subrange.h>
Expand All @@ -36,6 +37,7 @@
#include <__type_traits/is_swappable.h>
#include <__type_traits/is_trivially_relocatable.h>
#include <__type_traits/nat.h>
#include <__type_traits/reference_constructs_from_temporary.h>
#include <__type_traits/unwrap_ref.h>
#include <__utility/declval.h>
#include <__utility/forward.h>
Expand Down Expand Up @@ -68,9 +70,23 @@ struct __check_pair_construction {

template <class _U1, class _U2>
static _LIBCPP_HIDE_FROM_ABI constexpr bool __is_pair_constructible() {
# if _LIBCPP_STD_VER >= 23 && __has_builtin(__reference_constructs_from_temporary)
return is_constructible_v<_T1, _U1> && is_constructible_v<_T2, _U2> &&
!reference_constructs_from_temporary_v<_T1, _U1&&> && !reference_constructs_from_temporary_v<_T2, _U2&&>;
# else
return is_constructible<_T1, _U1>::value && is_constructible<_T2, _U2>::value;
# endif
}

# if _LIBCPP_STD_VER >= 23 && __has_builtin(__reference_constructs_from_temporary)
template <class _U1, class _U2>
static _LIBCPP_HIDE_FROM_ABI constexpr bool __is_pair_constructor_deleted() {
return is_constructible_v<_T1, _U1> && is_constructible_v<_T2, _U2> &&
(reference_constructs_from_temporary_v<_T1, _U1&&> || reference_constructs_from_temporary_v<_T2, _U2&&>);
return is_constructible<_T1, _U1>::value && is_constructible<_T2, _U2>::value;
}
# endif

template <class _U1, class _U2>
static _LIBCPP_HIDE_FROM_ABI constexpr bool __is_implicit() {
return is_convertible<_U1, _T1>::value && is_convertible<_U2, _T2>::value;
Expand Down Expand Up @@ -157,14 +173,20 @@ struct pair
class _U1,
class _U2,
# endif
__enable_if_t<__check_pair_construction<_T1, _T2>::template __is_pair_constructible<_U1, _U2>(), int> = 0 >
__enable_if_t<__check_pair_construction<_T1, _T2>::template __is_pair_constructible<_U1&&, _U2&&>(), int> = 0 >
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<_U1, _U2>())
_LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<_U1&&, _U2&&>())
pair(_U1&& __u1, _U2&& __u2) noexcept(is_nothrow_constructible<first_type, _U1>::value &&
is_nothrow_constructible<second_type, _U2>::value)
: first(std::forward<_U1>(__u1)), second(std::forward<_U2>(__u2)) {
}

# if _LIBCPP_STD_VER >= 23 && __has_builtin(__reference_constructs_from_temporary)
template <class _U1 = _T1, class _U2 = _T2>
requires(__check_pair_construction<_T1, _T2>::template __is_pair_constructor_deleted<_U1 &&, _U2 &&>())
explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<_U1&&, _U2&&>()) pair(_U1&&, _U2&&) = delete;
# endif

# if _LIBCPP_STD_VER >= 23
template <class _U1,
class _U2,
Expand All @@ -173,6 +195,12 @@ struct pair
pair(pair<_U1, _U2>& __p) noexcept((is_nothrow_constructible<first_type, _U1&>::value &&
is_nothrow_constructible<second_type, _U2&>::value))
: first(__p.first), second(__p.second) {}

# if __has_builtin(__reference_constructs_from_temporary)
template <class _U1, class _U2>
requires(__check_pair_construction<_T1, _T2>::template __is_pair_constructor_deleted<_U1&, _U2&>())
explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<_U1&, _U2&>()) pair(pair<_U1, _U2>&) = delete;
# endif
# endif

template <
Expand All @@ -186,15 +214,30 @@ struct pair
is_nothrow_constructible<second_type, _U2 const&>::value)
: first(__p.first), second(__p.second) {}

template <class _U1,
class _U2,
__enable_if_t<__check_pair_construction<_T1, _T2>::template __is_pair_constructible<_U1, _U2>(), int> = 0>
# if _LIBCPP_STD_VER >= 23 && __has_builtin(__reference_constructs_from_temporary)
template <class _U1, class _U2>
requires(__check_pair_construction<_T1, _T2>::template __is_pair_constructor_deleted<const _U1&, const _U2&>())
explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<const _U1&, const _U2&>())
pair(const pair<_U1, _U2>&) = delete;
# endif

template <
class _U1,
class _U2,
__enable_if_t<__check_pair_construction<_T1, _T2>::template __is_pair_constructible<_U1&&, _U2&&>(), int> = 0>
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<_U1, _U2>())
_LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<_U1&&, _U2&&>())
pair(pair<_U1, _U2>&& __p) noexcept(is_nothrow_constructible<first_type, _U1&&>::value &&
is_nothrow_constructible<second_type, _U2&&>::value)
: first(std::forward<_U1>(__p.first)), second(std::forward<_U2>(__p.second)) {}

# if _LIBCPP_STD_VER >= 23 && __has_builtin(__reference_constructs_from_temporary)
template <class _U1, class _U2>
requires(__check_pair_construction<_T1, _T2>::template __is_pair_constructor_deleted<_U1 &&, _U2 &&>())
explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<_U1&&, _U2&&>())
pair(pair<_U1, _U2>&&) = delete;
# endif

# if _LIBCPP_STD_VER >= 23
template <
class _U1,
Expand All @@ -206,16 +249,34 @@ struct pair
pair(const pair<_U1, _U2>&& __p) noexcept(is_nothrow_constructible<first_type, const _U1&&>::value &&
is_nothrow_constructible<second_type, const _U2&&>::value)
: first(std::move(__p.first)), second(std::move(__p.second)) {}

# if __has_builtin(__reference_constructs_from_temporary)
template <class _U1, class _U2>
requires(__check_pair_construction<_T1, _T2>::template __is_pair_constructor_deleted<const _U1 &&, const _U2 &&>())
explicit(!__check_pair_construction<_T1, _T2>::template __is_implicit<const _U1&&, const _U2&&>())
pair(const pair<_U1, _U2>&&) = delete;
# endif
# endif

# if _LIBCPP_STD_VER >= 23
template <__pair_like_no_subrange _PairLike>
requires(is_constructible_v<first_type, decltype(std::get<0>(std::declval<_PairLike &&>()))> &&
is_constructible_v<second_type, decltype(std::get<1>(std::declval<_PairLike &&>()))>)
requires(__check_pair_construction<_T1, _T2>::template __is_pair_constructible<
decltype(std::get<0>(std::declval<_PairLike &&>())),
decltype(std::get<1>(std::declval<_PairLike &&>()))>())
_LIBCPP_HIDE_FROM_ABI constexpr explicit(
!is_convertible_v<decltype(std::get<0>(std::declval<_PairLike&&>())), first_type> ||
!is_convertible_v<decltype(std::get<1>(std::declval<_PairLike&&>())), second_type>) pair(_PairLike&& __p)
: first(std::get<0>(std::forward<_PairLike>(__p))), second(std::get<1>(std::forward<_PairLike>(__p))) {}

# if __has_builtin(__reference_constructs_from_temporary)
template <__pair_like_no_subrange _PairLike>
requires(__check_pair_construction<_T1, _T2>::template __is_pair_constructor_deleted<
decltype(std::get<0>(std::declval<_PairLike &&>())),
decltype(std::get<1>(std::declval<_PairLike &&>()))>())
explicit(!is_convertible_v<decltype(std::get<0>(std::declval<_PairLike&&>())), first_type> ||
!is_convertible_v<decltype(std::get<1>(std::declval<_PairLike&&>())), second_type>)
pair(_PairLike&&) = delete;
# endif
# endif

template <class... _Args1, class... _Args2>
Expand Down
2 changes: 1 addition & 1 deletion libcxx/test/std/containers/container.adaptors/flat.map/flat.map.observers/comp.pass.cpp
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Expand Up @@ -35,7 +35,7 @@ constexpr bool test() {
assert(kc(1, 2));
assert(!kc(2, 1));
auto vc = m.value_comp();
ASSERT_SAME_TYPE(decltype(vc(std::make_pair(1, 2), std::make_pair(1, 2))), bool);
ASSERT_SAME_TYPE(decltype(vc(std::make_pair(1, '2'), std::make_pair(1, '2'))), bool);
assert(vc({1, '2'}, {2, '1'}));
assert(!vc({2, '1'}, {1, '2'}));
}
Expand Down
2 changes: 1 addition & 1 deletion ...est/std/containers/container.adaptors/flat.multimap/flat.multimap.observers/comp.pass.cpp
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Expand Up @@ -36,7 +36,7 @@ constexpr bool test() {
assert(kc(1, 2));
assert(!kc(2, 1));
auto vc = m.value_comp();
ASSERT_SAME_TYPE(decltype(vc(std::make_pair(1, 2), std::make_pair(1, 2))), bool);
ASSERT_SAME_TYPE(decltype(vc(std::make_pair(1, '2'), std::make_pair(1, '2'))), bool);
assert(vc({1, '2'}, {2, '1'}));
assert(!vc({2, '1'}, {1, '2'}));
}
Expand Down
12 changes: 11 additions & 1 deletion libcxx/test/std/utilities/utility/pairs/pairs.pair/ctor.U_V.pass.cpp
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Expand Up @@ -139,5 +139,15 @@ int main(int, char**)
}
#endif // TEST_STD_VER > 20

return 0;
// Test construction prohibition of introduced by https://wg21.link/P2255R2.
#if TEST_STD_VER >= 23 && __has_builtin(__reference_constructs_from_temporary)
test_sfinae<int&&, char, false>();
test_sfinae<const int&, char, false>();
test_sfinae<ConvertingType&&, int, false>();
test_sfinae<const ConvertingType&, char, false>();
test_sfinae<ExplicitTypes::ConvertingType&&, int, false>();
test_sfinae<const ExplicitTypes::ConvertingType&, int, false>();
#endif // TEST_STD_VER >= 23 && __has_builtin(__reference_constructs_from_temporary)

return 0;
}
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