[libc++] Fix LWG3557 "static_cast expression in convertible_to has the wrong operand"

https://cplusplus.github.io/LWG/issue3557
I think the code change is unobservable, so we could just close this as
"Nothing To Do" instead; but it seems appropriate to follow the Standard's
wording here as closely as possible.

Differential Revision: https://reviews.llvm.org/D117964
This commit is contained in:
Arthur O'Dwyer 2022-01-22 15:29:18 -05:00
parent ff84c635b7
commit 16031cbf2b
2 changed files with 4 additions and 3 deletions

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@ -114,7 +114,7 @@
`3498 <https://wg21.link/LWG3498>`__,"Inconsistent ``noexcept``-specifiers for ``basic_syncbuf``","October 2021","","" `3498 <https://wg21.link/LWG3498>`__,"Inconsistent ``noexcept``-specifiers for ``basic_syncbuf``","October 2021","",""
`3535 <https://wg21.link/LWG3535>`__,"``join_view::iterator::iterator_category`` and ``::iterator_concept`` lie","October 2021","","","|ranges|" `3535 <https://wg21.link/LWG3535>`__,"``join_view::iterator::iterator_category`` and ``::iterator_concept`` lie","October 2021","","","|ranges|"
`3554 <https://wg21.link/LWG3554>`__,"``chrono::parse`` needs ``const charT*`` and ``basic_string_view<charT>`` overloads","October 2021","","","|chrono|" `3554 <https://wg21.link/LWG3554>`__,"``chrono::parse`` needs ``const charT*`` and ``basic_string_view<charT>`` overloads","October 2021","","","|chrono|"
`3557 <https://wg21.link/LWG3557>`__,"The ``static_cast`` expression in ``convertible_to`` has the wrong operand","October 2021","","" `3557 <https://wg21.link/LWG3557>`__,"The ``static_cast`` expression in ``convertible_to`` has the wrong operand","October 2021","|Complete|","14.0"
`3559 <https://wg21.link/LWG3559>`__,"Semantic requirements of ``sized_range`` is circular","October 2021","","","|ranges|" `3559 <https://wg21.link/LWG3559>`__,"Semantic requirements of ``sized_range`` is circular","October 2021","","","|ranges|"
`3560 <https://wg21.link/LWG3560>`__,"``ranges::equal`` and ``ranges::is_permutation`` should short-circuit for ``sized_ranges``","October 2021","","","|ranges|" `3560 <https://wg21.link/LWG3560>`__,"``ranges::equal`` and ``ranges::is_permutation`` should short-circuit for ``sized_ranges``","October 2021","","","|ranges|"
`3561 <https://wg21.link/LWG3561>`__,"Issue with internal counter in ``discard_block_engine``","October 2021","","" `3561 <https://wg21.link/LWG3561>`__,"Issue with internal counter in ``discard_block_engine``","October 2021","",""

Can't render this file because it has a wrong number of fields in line 2.

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@ -10,6 +10,7 @@
#define _LIBCPP___CONCEPTS_CONVERTIBLE_TO_H #define _LIBCPP___CONCEPTS_CONVERTIBLE_TO_H
#include <__config> #include <__config>
#include <__utility/declval.h>
#include <type_traits> #include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@ -25,8 +26,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
template<class _From, class _To> template<class _From, class _To>
concept convertible_to = concept convertible_to =
is_convertible_v<_From, _To> && is_convertible_v<_From, _To> &&
requires (add_rvalue_reference_t<_From> (&__f)()) { requires {
static_cast<_To>(__f()); static_cast<_To>(declval<_From>());
}; };
#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS) #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)