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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-4612] libstdc++: Define atomic lock-free type aliases for C++20 [PR98034] Date: Mon, 12 Dec 2022 14:00:55 +0000 (GMT) [thread overview] Message-ID: <20221212140055.B13583852C4F@sourceware.org> (raw) https://gcc.gnu.org/g:320ac807da125e6dc952b3d4abf02daeead88d44 commit r13-4612-g320ac807da125e6dc952b3d4abf02daeead88d44 Author: Jonathan Wakely <jwakely@redhat.com> Date: Mon Dec 12 12:49:40 2022 +0000 libstdc++: Define atomic lock-free type aliases for C++20 [PR98034] libstdc++-v3/ChangeLog: PR libstdc++/98034 * include/std/atomic (__cpp_lib_atomic_lock_free_type_aliases): Define macro. (atomic_signed_lock_free, atomic_unsigned_lock_free): Define aliases. * include/std/version (__cpp_lib_atomic_lock_free_type_aliases): Define macro. * testsuite/29_atomics/atomic/lock_free_aliases.cc: New test. Diff: --- libstdc++-v3/include/std/atomic | 17 +++++++++++ libstdc++-v3/include/std/version | 1 + .../29_atomics/atomic/lock_free_aliases.cc | 34 ++++++++++++++++++++++ 3 files changed, 52 insertions(+) diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic index 356f1458f44..857f9270049 100644 --- a/libstdc++-v3/include/std/atomic +++ b/libstdc++-v3/include/std/atomic @@ -1727,6 +1727,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION using __atomic_ref<_Tp>::operator=; }; +#define __cpp_lib_atomic_lock_free_type_aliases 201907L +#ifdef _GLIBCXX_HAVE_PLATFORM_WAIT + using atomic_signed_lock_free + = atomic<make_signed_t<__detail::__platform_wait_t>>; + using atomic_unsigned_lock_free + = atomic<make_unsigned_t<__detail::__platform_wait_t>>; +#elif ATOMIC_INT_LOCK_FREE || !(ATOMIC_LONG_LOCK_FREE || ATOMIC_CHAR_LOCK_FREE) + using atomic_signed_lock_free = atomic<signed int>; + using atomic_unsigned_lock_free = atomic<unsigned int>; +#elif ATOMIC_LONG_LOCK_FREE + using atomic_signed_lock_free = atomic<signed long>; + using atomic_unsigned_lock_free = atomic<unsigned long>; +#elif ATOMIC_CHAR_LOCK_FREE + using atomic_signed_lock_free = atomic<signed char>; + using atomic_unsigned_lock_free = atomic<unsigned char>; +#endif + #endif // C++2a /// @} group atomics diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version index 3c7c440bd80..61718ebad74 100644 --- a/libstdc++-v3/include/std/version +++ b/libstdc++-v3/include/std/version @@ -187,6 +187,7 @@ #define __cpp_lib_assume_aligned 201811L #define __cpp_lib_atomic_flag_test 201907L #define __cpp_lib_atomic_float 201711L +#define __cpp_lib_atomic_lock_free_type_aliases 201907L #define __cpp_lib_atomic_ref 201806L #define __cpp_lib_atomic_value_initialization 201911L #define __cpp_lib_bind_front 201907L diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/lock_free_aliases.cc b/libstdc++-v3/testsuite/29_atomics/atomic/lock_free_aliases.cc new file mode 100644 index 00000000000..02c4ccc3aa3 --- /dev/null +++ b/libstdc++-v3/testsuite/29_atomics/atomic/lock_free_aliases.cc @@ -0,0 +1,34 @@ +// { dg-options "-std=gnu++20" } +// { dg-do compile { target c++20 } } + +#include <atomic> + +#ifndef __cpp_lib_atomic_lock_free_type_aliases +# error "Feature test macro for lock-free type aliases is missing in <atomic>" +#elif __cpp_lib_atomic_lock_free_type_aliases != 201907L +# error "Feature test macro for lock-free type aliases has wrong value in <atomic>" +#endif + +template<typename T> +constexpr bool is_atomic_specialization = false; +template<typename T> +constexpr bool is_atomic_specialization<std::atomic<T>> = true; + +// The type aliases atomic_signed_lock_free and atomic_unsigned_lock_free +// name specializations of atomic +static_assert( is_atomic_specialization<std::atomic_signed_lock_free> ); +static_assert( is_atomic_specialization<std::atomic_unsigned_lock_free> ); + +#include <type_traits> + +// ... whose template arguments are integral types, +static_assert( std::is_integral_v<std::atomic_signed_lock_free::value_type> ); +static_assert( std::is_integral_v<std::atomic_unsigned_lock_free::value_type> ); + +// ... respectively signed and unsigned, +static_assert( std::is_signed_v<std::atomic_signed_lock_free::value_type> ); +static_assert( std::is_unsigned_v<std::atomic_unsigned_lock_free::value_type> ); + +// and whose is_always_lock_free property is true. +static_assert( std::atomic_signed_lock_free::is_always_lock_free ); +static_assert( std::atomic_unsigned_lock_free::is_always_lock_free );
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