diff options
Diffstat (limited to 'absl/meta')
| -rw-r--r-- | absl/meta/type_traits.h | 45 | ||||
| -rw-r--r-- | absl/meta/type_traits_test.cc | 21 |
2 files changed, 37 insertions, 29 deletions
diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h index d57a8792..8cd5f043 100644 --- a/absl/meta/type_traits.h +++ b/absl/meta/type_traits.h @@ -41,10 +41,20 @@ #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 { // 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> struct is_trivially_move_assignable; namespace type_traits_internal { @@ -66,6 +76,20 @@ 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> @@ -323,7 +347,9 @@ 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 == @@ -354,10 +380,11 @@ 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 == @@ -388,10 +415,11 @@ 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 == @@ -423,7 +451,8 @@ 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 { diff --git a/absl/meta/type_traits_test.cc b/absl/meta/type_traits_test.cc index 6fbb42f8..1aafd0d4 100644 --- a/absl/meta/type_traits_test.cc +++ b/absl/meta/type_traits_test.cc @@ -347,21 +347,6 @@ class Base { virtual ~Base() {} }; -// In GCC/Clang, std::is_trivially_constructible requires that the destructor is -// trivial. However, MSVC doesn't require that. This results in different -// behavior when checking is_trivially_constructible on any type with -// nontrivial destructor. Since absl::is_trivially_default_constructible and -// absl::is_trivially_copy_constructible both follows Clang/GCC's interpretation -// and check is_trivially_destructible, it results in inconsistency with -// std::is_trivially_xxx_constructible on MSVC. This macro is used to work -// around this issue in test. In practice, a trivially constructible type -// should also be trivially destructible. -// GCC bug 51452: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51452 -// LWG issue 2116: http://cplusplus.github.io/LWG/lwg-active.html#2116 -#ifndef _MSC_VER -#define ABSL_TRIVIALLY_CONSTRUCTIBLE_VERIFY_TRIVIALLY_DESTRUCTIBLE 1 -#endif - // Old versions of libc++, around Clang 3.5 to 3.6, consider deleted destructors // as also being trivial. With the resolution of CWG 1928 and CWG 1734, this // is no longer considered true and has thus been amended. @@ -499,11 +484,9 @@ TEST(TypeTraitsTest, TestTrivialDefaultCtor) { EXPECT_FALSE( absl::is_trivially_default_constructible<DeletedDefaultCtor>::value); -#ifdef ABSL_TRIVIALLY_CONSTRUCTIBLE_VERIFY_TRIVIALLY_DESTRUCTIBLE // types with nontrivial destructor are nontrivial EXPECT_FALSE( absl::is_trivially_default_constructible<NontrivialDestructor>::value); -#endif // types with vtables EXPECT_FALSE(absl::is_trivially_default_constructible<Base>::value); @@ -607,11 +590,9 @@ TEST(TypeTraitsTest, TestTrivialMoveCtor) { EXPECT_FALSE( absl::is_trivially_move_constructible<NonCopyableOrMovable>::value); -#ifdef ABSL_TRIVIALLY_CONSTRUCTIBLE_VERIFY_TRIVIALLY_DESTRUCTIBLE // type with nontrivial destructor are nontrivial move construbtible EXPECT_FALSE( absl::is_trivially_move_constructible<NontrivialDestructor>::value); -#endif // types with vtables EXPECT_FALSE(absl::is_trivially_move_constructible<Base>::value); @@ -682,11 +663,9 @@ TEST(TypeTraitsTest, TestTrivialCopyCtor) { EXPECT_FALSE( absl::is_trivially_copy_constructible<NonCopyableOrMovable>::value); -#ifdef ABSL_TRIVIALLY_CONSTRUCTIBLE_VERIFY_TRIVIALLY_DESTRUCTIBLE // type with nontrivial destructor are nontrivial copy construbtible EXPECT_FALSE( absl::is_trivially_copy_constructible<NontrivialDestructor>::value); -#endif // types with vtables EXPECT_FALSE(absl::is_trivially_copy_constructible<Base>::value); |