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Use __is_same_as for std::is_same and std::is_same_v

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By using the built-in we don't need to match a partial specialization
for std::is_same and don't need to instantiate std::is_same at all for
uses of std::is_same_v.

	* include/std/type_traits (is_same): Replace partial specialization
	by using __is_same_as built-in in primary template.
	(is_same_v): Use __is_same_as built-in instead of instantiating the
	is_same trait.

From-SVN: r276891
This commit is contained in:
Jonathan Wakely 2019-10-11 16:53:44 +01:00 • committed by Jonathan Wakely
parent 07758d90c7
commit 02f6fdff65
2 changed files with 9 additions and 7 deletions
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5
libstdc++-v3/ChangeLog
View file

@ -1,5 +1,10 @@
2019-10-11 Jonathan Wakely <jwakely@redhat.com>
* include/std/type_traits (is_same): Replace partial specialization
by using __is_same_as built-in in primary template.
(is_same_v): Use __is_same_as built-in instead of instantiating the
is_same trait.
PR libstdc++/92059
* include/tr2/dynamic_bitset (__dynamic_bitset_base): Define all
special member functions as defaulted. Add noexcept to most members.

11
libstdc++-v3/include/std/type_traits
View file

@ -1388,13 +1388,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Type relations.
/// is_same
template<typename, typename>
template<typename _Tp, typename _Up>
struct is_same
: public false_type { };
template<typename _Tp>
struct is_same<_Tp, _Tp>
: public true_type { };
: public integral_constant<bool, __is_same_as(_Tp, _Up)>
{ };
/// is_base_of
template<typename _Base, typename _Derived>
@ -3158,7 +3155,7 @@ template <typename _Tp>
template <typename _Tp, unsigned _Idx = 0>
inline constexpr size_t extent_v = extent<_Tp, _Idx>::value;
template <typename _Tp, typename _Up>
inline constexpr bool is_same_v = is_same<_Tp, _Up>::value;
inline constexpr bool is_same_v = __is_same_as(_Tp, _Up);
template <typename _Base, typename _Derived>
inline constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
template <typename _From, typename _To>