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libstdc++: Optimize is_reference

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Instead of defining is_reference in terms of is_[lr]value_reference,
just define it directly.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_reference): Make the primary
	template derive from false_type.  Define two partial
	specializations that derive from true_type.
This commit is contained in:
Patrick Palka 2022-09-07 10:21:51 -04:00
parent 66af6e991b
commit cdcc27c1ca
1 changed files with 11 additions and 2 deletions
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13
libstdc++-v3/include/std/type_traits
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@ -611,8 +611,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_reference
template<typename _Tp>
struct is_reference
: public __or_<is_lvalue_reference<_Tp>,
is_rvalue_reference<_Tp>>::type
: public false_type
{ };
template<typename _Tp>
struct is_reference<_Tp&>
: public true_type
{ };
template<typename _Tp>
struct is_reference<_Tp&&>
: public true_type
{ };
/// is_arithmetic