From ca3f87560a0eef716195cadf66dc6b938a579ec6 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Tue, 23 Apr 2019 12:04:13 -0700 Subject: Export of internal Abseil changes. -- 5a5dba4252e764e6737070bf0a31074bf23a3b41 by Abseil Team : Internal change. PiperOrigin-RevId: 244898913 -- 3eb7d5b445ffbf08a104e39cd15aecf568417333 by Matt Calabrese : Introduce absl::is_trivially_move_constructible and absl::is_trivially_move_assignable, and update the absl::is_trivially_copy_constructible and absl::is_trivially_copy_assignable traits to use similar techniques (should now be closer to the standard behavior). PiperOrigin-RevId: 244859015 -- 7da05a24fa786cab3985de0c39a186d73dcbcfb5 by Abseil Team : Fix misspellings in comments in raw_hash_set.h. PiperOrigin-RevId: 244754700 -- 5c057be96048f21473d5ec45005ab4dcd8dd354f by Derek Mauro : Internal change PiperOrigin-RevId: 244744239 -- 592394e3c2e98f1238d3fb6fcb0d20c3e3739ba9 by Derek Mauro : Limit the raw_hash_set prefetch test to x86-64. PiperOrigin-RevId: 244737534 -- 99ebe4e003633c8ff7838b035b31a827994879ef by Derek Mauro : Workaround warning 4091 in an MSVC header. PiperOrigin-RevId: 244701744 -- 0aa23f09a32efe7985ee55b0217190f08da42477 by Abseil Team : Fix comment typo. PiperOrigin-RevId: 244659371 -- c6cdb87e9f28062c8daa29b3d8d68182ecc16383 by Derek Mauro : Fix -Wundef warnings and support -Wundef. PiperOrigin-RevId: 244244968 -- 06b81245f7696b20c3c63b0618d33ac25e29cad6 by Abseil Team : Fix a typo in inlined_vector.h. PiperOrigin-RevId: 244230809 -- 94877a2125d2cfe837384240e4d6551f39d737e4 by Greg Falcon : Fix sysinfo_test for emscripten. PiperOrigin-RevId: 244198804 -- ec7783531ef7f9df2da37d341d61f7cb2bf843f0 by Shaindel Schwartz : Import of CCTZ from GitHub. Fixes #291. PiperOrigin-RevId: 244184598 -- b652c14fa95ea206c217487ee713b11f5d1762b3 by Matt Calabrese : Emulate the `in_place_index` and `in_place_type` variable templates such that they are syntactically usable in C++11 with `any` and `variant`. Also pull in the variable templates from namespace std when available. The main observable differences here are: 1) The types of `in_place_index_t` and `in_place_type_t` become function pointer types rather than structs when using the implementation that is not an alias of the std equivalents. 2) The types of `in_place_index` and `in_place_type` are not directly `in_place_index_t` and `in_place_type_t`, but rather they become function types that decay to the corresponding function pointer types. 3) The default constructor for `in_place_index_t` and `in_place_type_t` instantiations is no longer explicit, but for these templates I think that's less important than for something like `in_place_t` since the _type_t and _index_t versions basically never have their template parameter non-deduced when participating in overload resolution with conflicting candidates. 4) While idiomatic usage of `in_place_type_t` and `in_place_index_t` with std::variant and std::any should not be affected, there is the possibility that strange, non-idiomatic uses may be affected in the wild. 5) Default construction (rather than value-initialization) leads to a default-constructed pointer. PiperOrigin-RevId: 244180003 -- b9ac5a96581837ffa24532117b7ea302a5569751 by Derek Mauro : Fix MSVC debug assertion. isprint is undefined for values not representable as unsigned char or EOF. PiperOrigin-RevId: 244083005 -- 41758be6137c2f25e84b50f23938e49484be2903 by Shaindel Schwartz : Update config settings for Apple platforms. PiperOrigin-RevId: 244040587 -- c90df6a26db94b0305a0c954455a621542a89d91 by Abseil Team : Internal change PiperOrigin-RevId: 244024427 -- c71e9ceb89495354eca7d02bd905ffeaa9029aec by Derek Mauro : Adds missing ABSL_DEFAULT_COPTS and ABSL_TEST_COPTS to CMakeLists.txt Don't error on deprecated declarations in tests. It is completely reasonable to test that code marked deprecated still works. PiperOrigin-RevId: 244003941 -- e1326a96527a8ba9b8d120161545260da9c4562e by Abseil Team : Internal change. PiperOrigin-RevId: 243990623 -- 90b8e12934c7711e1bfcc0117d21288bf9220dee by Abseil Team : Add variation of absl::Base64Escape/WebSafeBase64Escape that directly returns its result. PiperOrigin-RevId: 243894308 -- 317fef3344481ebc5c35712d42f5d8a0fa64dff4 by Abseil Team : Enable raw logging in Emscripten builds. PiperOrigin-RevId: 243893705 GitOrigin-RevId: 5a5dba4252e764e6737070bf0a31074bf23a3b41 Change-Id: I19293aab73cc98d9e9bf6a9fdc30819764adb9db --- absl/meta/type_traits.h | 109 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 106 insertions(+), 3 deletions(-) (limited to 'absl/meta/type_traits.h') diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h index a8068e3..c08e375 100644 --- a/absl/meta/type_traits.h +++ b/absl/meta/type_traits.h @@ -43,8 +43,39 @@ namespace absl { +// Defined and documented later on in this file. +template +struct is_trivially_move_assignable; + namespace type_traits_internal { +// Silence MSVC warnings about the destructor being defined as deleted. +#if defined(_MSC_VER) && !defined(__GNUC__) +#pragma warning(push) +#pragma warning(disable : 4624) +#endif // defined(_MSC_VER) && !defined(__GNUC__) + +template +union SingleMemberUnion { + T t; +}; + +// Restore the state of the destructor warning that was silenced above. +#if defined(_MSC_VER) && !defined(__GNUC__) +#pragma warning(pop) +#endif // defined(_MSC_VER) && !defined(__GNUC__) + +template +struct IsTriviallyMoveAssignableReference : std::false_type {}; + +template +struct IsTriviallyMoveAssignableReference + : absl::is_trivially_move_assignable::type {}; + +template +struct IsTriviallyMoveAssignableReference + : absl::is_trivially_move_assignable::type {}; + template struct VoidTImpl { using type = void; @@ -275,6 +306,40 @@ struct is_trivially_default_constructible #endif // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE }; +// is_trivially_move_constructible() +// +// Determines whether the passed type `T` is trivially move constructible. +// +// This metafunction is designed to be a drop-in replacement for the C++11 +// `std::is_trivially_move_constructible()` metafunction for platforms that have +// incomplete C++11 support (such as libstdc++ 4.x). On any platforms that do +// fully support C++11, we check whether this yields the same result as the std +// implementation. +// +// NOTE: `T obj(declval());` needs to be well-formed and not call any +// nontrivial operation. Nontrivially destructible types will cause the +// expression to be nontrivial. +template +struct is_trivially_move_constructible + : std::conditional< + std::is_object::value && !std::is_array::value, + std::is_move_constructible< + type_traits_internal::SingleMemberUnion>, + std::is_reference>::type::type { +#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE + private: + static constexpr bool compliant = + std::is_trivially_move_constructible::value == + is_trivially_move_constructible::value; + static_assert(compliant || std::is_trivially_move_constructible::value, + "Not compliant with std::is_trivially_move_constructible; " + "Standard: false, Implementation: true"); + static_assert(compliant || !std::is_trivially_move_constructible::value, + "Not compliant with std::is_trivially_move_constructible; " + "Standard: true, Implementation: false"); +#endif // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE +}; + // is_trivially_copy_constructible() // // Determines whether the passed type `T` is trivially copy constructible. @@ -290,9 +355,11 @@ struct is_trivially_default_constructible // expression to be nontrivial. template struct is_trivially_copy_constructible - : std::integral_constant::value && - is_trivially_destructible::value> { + : std::conditional< + std::is_object::value && !std::is_array::value, + std::is_copy_constructible< + type_traits_internal::SingleMemberUnion>, + std::is_lvalue_reference>::type::type { #ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE private: static constexpr bool compliant = @@ -307,6 +374,42 @@ struct is_trivially_copy_constructible #endif // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE }; +// is_trivially_move_assignable() +// +// Determines whether the passed type `T` is trivially move assignable. +// +// This metafunction is designed to be a drop-in replacement for the C++11 +// `std::is_trivially_move_assignable()` metafunction for platforms that have +// incomplete C++11 support (such as libstdc++ 4.x). On any platforms that do +// fully support C++11, we check whether this yields the same result as the std +// implementation. +// +// NOTE: `is_assignable::value` is `true` if the expression +// `declval() = declval()` is well-formed when treated as an unevaluated +// operand. `is_trivially_assignable` requires the assignment to call no +// operation that is not trivial. `is_trivially_copy_assignable` is simply +// `is_trivially_assignable`. +template +struct is_trivially_move_assignable + : std::conditional< + std::is_object::value && !std::is_array::value, + std::is_move_assignable>, + type_traits_internal::IsTriviallyMoveAssignableReference>::type:: + type { +#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE + private: + static constexpr bool compliant = + std::is_trivially_move_assignable::value == + is_trivially_move_assignable::value; + static_assert(compliant || std::is_trivially_move_assignable::value, + "Not compliant with std::is_trivially_move_assignable; " + "Standard: false, Implementation: true"); + static_assert(compliant || !std::is_trivially_move_assignable::value, + "Not compliant with std::is_trivially_move_assignable; " + "Standard: true, Implementation: false"); +#endif // ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE +}; + // is_trivially_copy_assignable() // // Determines whether the passed type `T` is trivially copy assignable. -- cgit v1.2.3