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Define __type_identity_t alias and use for string_view

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This defines the equivalent of C++2a's std::type_identity_t alias but
for use in C++11 and later. This can be used to replace __detail::__idt
in the string_view headers, which previously used common_type_t because
the one argument specialization of common_type_t was simply the identity
transform (which is no longer true).

	* include/experimental/string_view (__detail::__idt): Remove.
	(operator==, operator!=, operator<, operator>, operator<=, operator>=):
	Use __type_identity_t instead of __detail::__idt;
	* include/std/string_view (__detail::__idt): Remove.
	(operator==, operator!=, operator<, operator>, operator<=, operator>=):
	Use __type_identity_t instead of __detail::__idt;
	* include/std/type_traits (__type_identity_t): New alias template.

From-SVN: r273442
This commit is contained in:
Jonathan Wakely 2019-07-12 12:43:22 +01:00 • committed by Jonathan Wakely
parent 804e2d0631
commit 0d67cd380d
4 changed files with 57 additions and 43 deletions
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8
libstdc++-v3/ChangeLog
View file

@ -1,5 +1,13 @@
2019-07-12 Jonathan Wakely <jwakely@redhat.com>
* include/experimental/string_view (__detail::__idt): Remove.
(operator==, operator!=, operator<, operator>, operator<=, operator>=):
Use __type_identity_t instead of __detail::__idt;
* include/std/string_view (__detail::__idt): Remove.
(operator==, operator!=, operator<, operator>, operator<=, operator>=):
Use __type_identity_t instead of __detail::__idt;
* include/std/type_traits (__type_identity_t): New alias template.
* doc/xml/manual/status_cxx2020.xml: Update status for atomic_ref
and floating point atomics.

42
libstdc++-v3/include/experimental/string_view
View file

@ -436,14 +436,10 @@ inline namespace fundamentals_v1
// [string.view.comparison], non-member basic_string_view comparison functions
namespace __detail
{
// Identity transform to create a non-deduced context, so that only one
// argument participates in template argument deduction and the other
// argument gets implicitly converted to the deduced type. See n3766.html.
template<typename _Tp>
using __idt = common_type_t<_Tp>;
}
// Several of these functions use type_identity_t to create a non-deduced
// context, so that only one argument participates in template argument
// deduction and the other argument gets implicitly converted to the deduced
// type (see N3766).
template<typename _CharT, typename _Traits>
constexpr bool
@ -454,12 +450,13 @@ inline namespace fundamentals_v1
template<typename _CharT, typename _Traits>
constexpr bool
operator==(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.size() == __y.size() && __x.compare(__y) == 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator==(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.size() == __y.size() && __x.compare(__y) == 0; }
@ -472,12 +469,13 @@ inline namespace fundamentals_v1
template<typename _CharT, typename _Traits>
constexpr bool
operator!=(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return !(__x == __y); }
template<typename _CharT, typename _Traits>
constexpr bool
operator!=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return !(__x == __y); }
@ -490,12 +488,13 @@ inline namespace fundamentals_v1
template<typename _CharT, typename _Traits>
constexpr bool
operator< (basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) < 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator< (__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) < 0; }
@ -508,12 +507,13 @@ inline namespace fundamentals_v1
template<typename _CharT, typename _Traits>
constexpr bool
operator> (basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) > 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator> (__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) > 0; }
@ -526,12 +526,13 @@ inline namespace fundamentals_v1
template<typename _CharT, typename _Traits>
constexpr bool
operator<=(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) <= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator<=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) <= 0; }
@ -544,12 +545,13 @@ inline namespace fundamentals_v1
template<typename _CharT, typename _Traits>
constexpr bool
operator>=(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) >= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator>=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) >= 0; }

42
libstdc++-v3/include/std/string_view
View file

@ -459,14 +459,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// [string.view.comparison], non-member basic_string_view comparison function
namespace __detail
{
// Identity transform to create a non-deduced context, so that only one
// argument participates in template argument deduction and the other
// argument gets implicitly converted to the deduced type. See n3766.html.
template<typename _Tp>
using __idt = common_type_t<_Tp>;
}
// Several of these functions use type_identity_t to create a non-deduced
// context, so that only one argument participates in template argument
// deduction and the other argument gets implicitly converted to the deduced
// type (see N3766).
template<typename _CharT, typename _Traits>
constexpr bool
@ -477,12 +473,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr bool
operator==(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.size() == __y.size() && __x.compare(__y) == 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator==(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.size() == __y.size() && __x.compare(__y) == 0; }
@ -495,12 +492,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr bool
operator!=(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return !(__x == __y); }
template<typename _CharT, typename _Traits>
constexpr bool
operator!=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return !(__x == __y); }
@ -513,12 +511,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr bool
operator< (basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) < 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator< (__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) < 0; }
@ -531,12 +530,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr bool
operator> (basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) > 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator> (__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) > 0; }
@ -549,12 +549,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr bool
operator<=(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) <= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator<=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) <= 0; }
@ -567,12 +568,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr bool
operator>=(basic_string_view<_CharT, _Traits> __x,
__detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) >= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator>=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) >= 0; }

8
libstdc++-v3/include/std/type_traits
View file

@ -92,9 +92,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct conditional;
template <typename _Type>
struct __type_identity {
using type = _Type;
};
struct __type_identity
{ using type = _Type; };
template<typename _Tp>
using __type_identity_t = typename __type_identity<_Tp>::type;
template<typename...>
struct __or_;