diff options
Diffstat (limited to 'absl/meta/type_traits.h')
| -rw-r--r-- | absl/meta/type_traits.h | 65 |
1 files changed, 54 insertions, 11 deletions
diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h index ae7130dd..ba87d2f0 100644 --- a/absl/meta/type_traits.h +++ b/absl/meta/type_traits.h @@ -41,8 +41,18 @@ #include "absl/base/config.h" +// MSVC constructibility traits do not detect destructor properties and so our +// implementations should not use them as a source-of-truth. +#if defined(_MSC_VER) && !defined(__clang__) && !defined(__GNUC__) +#define ABSL_META_INTERNAL_STD_CONSTRUCTION_TRAITS_DONT_CHECK_DESTRUCTION 1 +#endif + namespace absl { -inline namespace lts_2019_08_08 { +ABSL_NAMESPACE_BEGIN + +// Defined and documented later on in this file. +template <typename T> +struct is_trivially_destructible; // Defined and documented later on in this file. template <typename T> @@ -67,6 +77,20 @@ union SingleMemberUnion { #endif // defined(_MSC_VER) && !defined(__GNUC__) template <class T> +struct IsTriviallyMoveConstructibleObject + : std::integral_constant< + bool, std::is_move_constructible< + type_traits_internal::SingleMemberUnion<T>>::value && + absl::is_trivially_destructible<T>::value> {}; + +template <class T> +struct IsTriviallyCopyConstructibleObject + : std::integral_constant< + bool, std::is_copy_constructible< + type_traits_internal::SingleMemberUnion<T>>::value && + absl::is_trivially_destructible<T>::value> {}; + +template <class T> struct IsTriviallyMoveAssignableReference : std::false_type {}; template <class T> @@ -146,6 +170,18 @@ using IsMoveAssignableImpl = decltype(std::declval<T&>() = std::declval<T&&>()); } // namespace type_traits_internal +// MSVC 19.20 has a regression that causes our workarounds to fail, but their +// std forms now appear to be compliant. +#if defined(_MSC_VER) && !defined(__clang__) && (_MSC_VER >= 1920) + +template <typename T> +using is_copy_assignable = std::is_copy_assignable<T>; + +template <typename T> +using is_move_assignable = std::is_move_assignable<T>; + +#else + template <typename T> struct is_copy_assignable : type_traits_internal::is_detected< type_traits_internal::IsCopyAssignableImpl, T> { @@ -156,6 +192,8 @@ struct is_move_assignable : type_traits_internal::is_detected< type_traits_internal::IsMoveAssignableImpl, T> { }; +#endif + // void_t() // // Ignores the type of any its arguments and returns `void`. In general, this @@ -244,7 +282,7 @@ struct is_function // is_trivially_destructible() // -// Determines whether the passed type `T` is trivially destructable. +// Determines whether the passed type `T` is trivially destructible. // // This metafunction is designed to be a drop-in replacement for the C++11 // `std::is_trivially_destructible()` metafunction for platforms that have @@ -310,7 +348,9 @@ struct is_trivially_default_constructible : std::integral_constant<bool, __has_trivial_constructor(T) && std::is_default_constructible<T>::value && is_trivially_destructible<T>::value> { -#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE +#if defined(ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE) && \ + !defined( \ + ABSL_META_INTERNAL_STD_CONSTRUCTION_TRAITS_DONT_CHECK_DESTRUCTION) private: static constexpr bool compliant = std::is_trivially_default_constructible<T>::value == @@ -341,10 +381,11 @@ template <typename T> struct is_trivially_move_constructible : std::conditional< std::is_object<T>::value && !std::is_array<T>::value, - std::is_move_constructible< - type_traits_internal::SingleMemberUnion<T>>, + type_traits_internal::IsTriviallyMoveConstructibleObject<T>, std::is_reference<T>>::type::type { -#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE +#if defined(ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE) && \ + !defined( \ + ABSL_META_INTERNAL_STD_CONSTRUCTION_TRAITS_DONT_CHECK_DESTRUCTION) private: static constexpr bool compliant = std::is_trivially_move_constructible<T>::value == @@ -375,10 +416,11 @@ template <typename T> struct is_trivially_copy_constructible : std::conditional< std::is_object<T>::value && !std::is_array<T>::value, - std::is_copy_constructible< - type_traits_internal::SingleMemberUnion<T>>, + type_traits_internal::IsTriviallyCopyConstructibleObject<T>, std::is_lvalue_reference<T>>::type::type { -#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE +#if defined(ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE) && \ + !defined( \ + ABSL_META_INTERNAL_STD_CONSTRUCTION_TRAITS_DONT_CHECK_DESTRUCTION) private: static constexpr bool compliant = std::is_trivially_copy_constructible<T>::value == @@ -410,7 +452,8 @@ struct is_trivially_copy_constructible template <typename T> struct is_trivially_move_assignable : std::conditional< - std::is_object<T>::value && !std::is_array<T>::value, + std::is_object<T>::value && !std::is_array<T>::value && + std::is_move_assignable<T>::value, std::is_move_assignable<type_traits_internal::SingleMemberUnion<T>>, type_traits_internal::IsTriviallyMoveAssignableReference<T>>::type:: type { @@ -710,7 +753,7 @@ using swap_internal::Swap; using swap_internal::StdSwapIsUnconstrained; } // namespace type_traits_internal -} // inline namespace lts_2019_08_08 +ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_META_TYPE_TRAITS_H_ |