diff options
Diffstat (limited to 'libcxx/include/__type_traits/is_equality_comparable.h')
| -rw-r--r-- | libcxx/include/__type_traits/is_equality_comparable.h | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/libcxx/include/__type_traits/is_equality_comparable.h b/libcxx/include/__type_traits/is_equality_comparable.h index b7a7cd219e30..381108365c00 100644 --- a/libcxx/include/__type_traits/is_equality_comparable.h +++ b/libcxx/include/__type_traits/is_equality_comparable.h @@ -15,6 +15,7 @@ #include <__type_traits/is_same.h> #include <__type_traits/is_void.h> #include <__type_traits/remove_cv.h> +#include <__type_traits/remove_cvref.h> #include <__type_traits/void_t.h> #include <__utility/declval.h> @@ -32,8 +33,9 @@ struct __is_equality_comparable<_Tp, _Up, __void_t<decltype(std::declval<_Tp>() }; // A type is_trivially_equality_comparable if the expression `a == b` is equivalent to `std::memcmp(&a, &b, sizeof(T))` -// (with `a` and `b` being of type `T`). There is no compiler built-in to check this, so we can only do this for known -// types. In particular, these are the integral types and raw pointers. +// (with `a` and `b` being of type `T`). For the case where we compare two object of the same type, we can use +// __is_trivially_equality_comparable. We have special-casing for pointers which point to the same type ignoring +// cv-qualifications and comparing to void-pointers. // // The following types are not trivially equality comparable: // floating-point types: different bit-patterns can compare equal. (e.g 0.0 and -0.0) @@ -43,20 +45,34 @@ struct __is_equality_comparable<_Tp, _Up, __void_t<decltype(std::declval<_Tp>() // always compared. template <class _Tp, class _Up> -struct __libcpp_is_trivially_equality_comparable - : integral_constant<bool, - __is_equality_comparable<_Tp, _Up>::value && is_integral<_Tp>::value && - is_same<__remove_cv_t<_Tp>, __remove_cv_t<_Up> >::value> {}; +struct __libcpp_is_trivially_equality_comparable_impl : false_type {}; + +template <class _Tp> +struct __libcpp_is_trivially_equality_comparable_impl<_Tp, _Tp> +#if __has_builtin(__is_trivially_equality_comparable) + : integral_constant<bool, __is_trivially_equality_comparable(_Tp) && __is_equality_comparable<_Tp, _Tp>::value> { +}; +#else + : is_integral<_Tp> { +}; +#endif // __has_builtin(__is_trivially_equality_comparable) + +template <class _Tp> +struct __libcpp_is_trivially_equality_comparable_impl<_Tp*, _Tp*> : true_type {}; // TODO: Use is_pointer_inverconvertible_base_of template <class _Tp, class _Up> -struct __libcpp_is_trivially_equality_comparable<_Tp*, _Up*> +struct __libcpp_is_trivially_equality_comparable_impl<_Tp*, _Up*> : integral_constant< bool, __is_equality_comparable<_Tp*, _Up*>::value && (is_same<__remove_cv_t<_Tp>, __remove_cv_t<_Up> >::value || is_void<_Tp>::value || is_void<_Up>::value)> { }; +template <class _Tp, class _Up> +using __libcpp_is_trivially_equality_comparable = + __libcpp_is_trivially_equality_comparable_impl<__remove_cv_t<_Tp>, __remove_cv_t<_Up> >; + _LIBCPP_END_NAMESPACE_STD #endif // _LIBCPP___TYPE_TRAITS_IS_EQUAILITY_COMPARABLE_H |