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| author | Patrick Palka <ppalka@redhat.com> | 2022-09-07 10:21:45 -0400 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2022-09-07 10:21:45 -0400 |
| commit | 66af6e991bf0daf1c41e46400a8f19e87c358cf2 (patch) | |
| tree | 93c355e894f77239c489beda6bcdf2f94074e160 /libstdc++-v3 | |
| parent | 873d395c2976a8321cec03f21d77e11f746da7c0 (diff) | |
| download | gcc-66af6e991bf0daf1c41e46400a8f19e87c358cf2.zip gcc-66af6e991bf0daf1c41e46400a8f19e87c358cf2.tar.gz gcc-66af6e991bf0daf1c41e46400a8f19e87c358cf2.tar.bz2 | |
libstdc++: Optimize is_void and is_null_pointer
Instead of defining these in terms of a helper class template
and the relatively expensive __remove_cv_t, just declare four
explicit specializations of the main template, one for each choice
of cv-quals.
libstdc++-v3/ChangeLog:
* include/std/type_traits (__is_void_helper): Remove.
(is_void): Make the primary template derive from false_type,
and define four explicit specializations that derive from
true_type.
(__is_null_pointer_helper, is_null_pointer): Likewise.
Diffstat (limited to 'libstdc++-v3')
| -rw-r--r-- | libstdc++-v3/include/std/type_traits | 48 |
1 files changed, 31 insertions, 17 deletions
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits index e4d1679..b83e725 100644 --- a/libstdc++-v3/include/std/type_traits +++ b/libstdc++-v3/include/std/type_traits @@ -289,23 +289,30 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // __remove_cv_t (std::remove_cv_t for C++11). template<typename _Tp> using __remove_cv_t = typename remove_cv<_Tp>::type; + /// @endcond // Primary type categories. - template<typename> - struct __is_void_helper + /// is_void + template<typename _Tp> + struct is_void : public false_type { }; template<> - struct __is_void_helper<void> + struct is_void<void> : public true_type { }; - /// @endcond - /// is_void - template<typename _Tp> - struct is_void - : public __is_void_helper<__remove_cv_t<_Tp>>::type - { }; + template<> + struct is_void<const void> + : public true_type { }; + + template<> + struct is_void<volatile void> + : public true_type { }; + + template<> + struct is_void<const volatile void> + : public true_type { }; /// @cond undocumented template<typename> @@ -571,19 +578,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #define __cpp_lib_is_null_pointer 201309L - template<typename> - struct __is_null_pointer_helper + /// is_null_pointer (LWG 2247). + template<typename _Tp> + struct is_null_pointer : public false_type { }; template<> - struct __is_null_pointer_helper<std::nullptr_t> + struct is_null_pointer<std::nullptr_t> : public true_type { }; - /// is_null_pointer (LWG 2247). - template<typename _Tp> - struct is_null_pointer - : public __is_null_pointer_helper<__remove_cv_t<_Tp>>::type - { }; + template<> + struct is_null_pointer<const std::nullptr_t> + : public true_type { }; + + template<> + struct is_null_pointer<volatile std::nullptr_t> + : public true_type { }; + + template<> + struct is_null_pointer<const volatile std::nullptr_t> + : public true_type { }; /// __is_nullptr_t (deprecated extension). /// @deprecated Non-standard. Use `is_null_pointer` instead. |