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[libc++] Drop support for the C++20 Synchronization Library before C++20 #82008

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Jul 31, 2024
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[libc++] Drop support for the C++20 Synchronization Library before C++20 #82008

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1 change: 0 additions & 1 deletion libcxx/.clang-format
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Expand Up @@ -24,7 +24,6 @@ AttributeMacros: [
'_LIBCPP_CONSTEXPR_SINCE_CXX23',
'_LIBCPP_CONSTEXPR',
'_LIBCPP_CONSTINIT',
'_LIBCPP_DEPRECATED_ATOMIC_SYNC',
'_LIBCPP_DEPRECATED_IN_CXX11',
'_LIBCPP_DEPRECATED_IN_CXX14',
'_LIBCPP_DEPRECATED_IN_CXX17',
Expand Down
4 changes: 3 additions & 1 deletion libcxx/docs/ReleaseNotes/20.rst
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Expand Up @@ -53,7 +53,9 @@ Deprecations and Removals
- TODO: The ``LIBCXX_ENABLE_ASSERTIONS`` CMake variable and the ``_LIBCPP_ENABLE_ASSERTIONS`` macro that were used to enable
the safe mode will be removed in LLVM 20.

- TODO: The C++20 synchronization library will be removed entirely in language modes prior to C++20 in LLVM 20.
- Support for the C++20 synchronization library (``<barrier>``, ``<latch>``, ``atomic::wait``, etc.) has been
removed in language modes prior to C++20. If you are using these features prior to C++20, you will need to
update to ``-std=c++20``.

- TODO: The relational operators for ``std::chrono::weekday`` will be removed entirely, and the
``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro that was used to re-enable this extension will be
Expand Down
16 changes: 8 additions & 8 deletions libcxx/include/__atomic/atomic.h
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Expand Up @@ -429,6 +429,8 @@ _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
return __o->compare_exchange_strong(*__e, __d, __s, __f);
}

#if _LIBCPP_STD_VER >= 20

// atomic_wait

template <class _Tp>
Expand Down Expand Up @@ -462,29 +464,27 @@ atomic_wait_explicit(const atomic<_Tp>* __o, typename atomic<_Tp>::value_type __
// atomic_notify_one

template <class _Tp>
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
atomic_notify_one(volatile atomic<_Tp>* __o) _NOEXCEPT {
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void atomic_notify_one(volatile atomic<_Tp>* __o) _NOEXCEPT {
__o->notify_one();
}
template <class _Tp>
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
atomic_notify_one(atomic<_Tp>* __o) _NOEXCEPT {
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void atomic_notify_one(atomic<_Tp>* __o) _NOEXCEPT {
__o->notify_one();
}

// atomic_notify_all

template <class _Tp>
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
atomic_notify_all(volatile atomic<_Tp>* __o) _NOEXCEPT {
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void atomic_notify_all(volatile atomic<_Tp>* __o) _NOEXCEPT {
__o->notify_all();
}
template <class _Tp>
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
atomic_notify_all(atomic<_Tp>* __o) _NOEXCEPT {
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void atomic_notify_all(atomic<_Tp>* __o) _NOEXCEPT {
__o->notify_all();
}

#endif // _LIBCPP_STD_VER >= 20

// atomic_fetch_add

template <class _Tp>
Expand Down
2 changes: 2 additions & 0 deletions libcxx/include/__atomic/atomic_base.h
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Expand Up @@ -101,6 +101,7 @@ struct __atomic_base // false
return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
}

#if _LIBCPP_STD_VER >= 20
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(_Tp __v, memory_order __m = memory_order_seq_cst) const
volatile _NOEXCEPT {
std::__atomic_wait(*this, __v, __m);
Expand All @@ -117,6 +118,7 @@ struct __atomic_base // false
std::__atomic_notify_all(*this);
}
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT { std::__atomic_notify_all(*this); }
#endif // _LIBCPP_STD_VER >= 20

#if _LIBCPP_STD_VER >= 20
_LIBCPP_HIDE_FROM_ABI constexpr __atomic_base() noexcept(is_nothrow_default_constructible_v<_Tp>) : __a_(_Tp()) {}
Expand Down
38 changes: 18 additions & 20 deletions libcxx/include/__atomic/atomic_flag.h
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Expand Up @@ -48,26 +48,24 @@ struct atomic_flag {
__cxx_atomic_store(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(false), __m);
}

_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
wait(bool __v, memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT {
#if _LIBCPP_STD_VER >= 20
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(bool __v, memory_order __m = memory_order_seq_cst) const
volatile _NOEXCEPT {
std::__atomic_wait(*this, _LIBCPP_ATOMIC_FLAG_TYPE(__v), __m);
}
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
wait(bool __v, memory_order __m = memory_order_seq_cst) const _NOEXCEPT {
std::__atomic_wait(*this, _LIBCPP_ATOMIC_FLAG_TYPE(__v), __m);
}
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() volatile _NOEXCEPT {
std::__atomic_notify_one(*this);
}
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT {
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() volatile _NOEXCEPT {
std::__atomic_notify_one(*this);
}
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT { std::__atomic_notify_one(*this); }
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() volatile _NOEXCEPT {
std::__atomic_notify_all(*this);
}
_LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT {
std::__atomic_notify_all(*this);
}
_LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT { std::__atomic_notify_all(*this); }
#endif

#if _LIBCPP_STD_VER >= 20
_LIBCPP_HIDE_FROM_ABI constexpr atomic_flag() _NOEXCEPT : __a_(false) {}
Expand Down Expand Up @@ -144,45 +142,45 @@ inline _LIBCPP_HIDE_FROM_ABI void atomic_flag_clear_explicit(atomic_flag* __o, m
__o->clear(__m);
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
#if _LIBCPP_STD_VER >= 20
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_wait(const volatile atomic_flag* __o, bool __v) _NOEXCEPT {
__o->wait(__v);
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_wait(const atomic_flag* __o, bool __v) _NOEXCEPT {
__o->wait(__v);
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_wait_explicit(const volatile atomic_flag* __o, bool __v, memory_order __m) _NOEXCEPT {
__o->wait(__v, __m);
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_wait_explicit(const atomic_flag* __o, bool __v, memory_order __m) _NOEXCEPT {
__o->wait(__v, __m);
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_notify_one(volatile atomic_flag* __o) _NOEXCEPT {
__o->notify_one();
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_notify_one(atomic_flag* __o) _NOEXCEPT {
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void atomic_flag_notify_one(atomic_flag* __o) _NOEXCEPT {
__o->notify_one();
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_notify_all(volatile atomic_flag* __o) _NOEXCEPT {
__o->notify_all();
}

inline _LIBCPP_DEPRECATED_ATOMIC_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void
atomic_flag_notify_all(atomic_flag* __o) _NOEXCEPT {
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_SYNC void atomic_flag_notify_all(atomic_flag* __o) _NOEXCEPT {
__o->notify_all();
}
#endif // _LIBCPP_STD_VER >= 20

_LIBCPP_END_NAMESPACE_STD

Expand Down
8 changes: 0 additions & 8 deletions libcxx/include/__config
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Expand Up @@ -699,14 +699,6 @@ typedef __char32_t char32_t;
# define _LIBCPP_DEPRECATED_(m)
# endif

# if _LIBCPP_STD_VER < 20
# define _LIBCPP_DEPRECATED_ATOMIC_SYNC \
_LIBCPP_DEPRECATED_("The C++20 synchronization library has been deprecated prior to C++20. Please update to " \
"using -std=c++20 if you need to use these facilities.")
# else
# define _LIBCPP_DEPRECATED_ATOMIC_SYNC /* nothing */
# endif

# if !defined(_LIBCPP_CXX03_LANG)
# define _LIBCPP_DEPRECATED_IN_CXX11 _LIBCPP_DEPRECATED
# else
Expand Down
92 changes: 46 additions & 46 deletions libcxx/include/atomic
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Expand Up @@ -101,12 +101,12 @@ struct atomic
bool compare_exchange_strong(T& expc, T desr,
memory_order m = memory_order_seq_cst) noexcept;

void wait(T, memory_order = memory_order::seq_cst) const volatile noexcept;
void wait(T, memory_order = memory_order::seq_cst) const noexcept;
void notify_one() volatile noexcept;
void notify_one() noexcept;
void notify_all() volatile noexcept;
void notify_all() noexcept;
void wait(T, memory_order = memory_order::seq_cst) const volatile noexcept; // since C++20
void wait(T, memory_order = memory_order::seq_cst) const noexcept; // since C++20
void notify_one() volatile noexcept; // since C++20
void notify_one() noexcept; // since C++20
void notify_all() volatile noexcept; // since C++20
void notify_all() noexcept; // since C++20
};

template <>
Expand Down Expand Up @@ -184,12 +184,12 @@ struct atomic<integral>
integral operator^=(integral op) volatile noexcept;
integral operator^=(integral op) noexcept;

void wait(integral, memory_order = memory_order::seq_cst) const volatile noexcept;
void wait(integral, memory_order = memory_order::seq_cst) const noexcept;
void notify_one() volatile noexcept;
void notify_one() noexcept;
void notify_all() volatile noexcept;
void notify_all() noexcept;
void wait(integral, memory_order = memory_order::seq_cst) const volatile noexcept; // since C++20
void wait(integral, memory_order = memory_order::seq_cst) const noexcept; // since C++20
void notify_one() volatile noexcept; // since C++20
void notify_one() noexcept; // since C++20
void notify_all() volatile noexcept; // since C++20
void notify_all() noexcept; // since C++20
};

template <class T>
Expand Down Expand Up @@ -254,12 +254,12 @@ struct atomic<T*>
T* operator-=(ptrdiff_t op) volatile noexcept;
T* operator-=(ptrdiff_t op) noexcept;

void wait(T*, memory_order = memory_order::seq_cst) const volatile noexcept;
void wait(T*, memory_order = memory_order::seq_cst) const noexcept;
void notify_one() volatile noexcept;
void notify_one() noexcept;
void notify_all() volatile noexcept;
void notify_all() noexcept;
void wait(T*, memory_order = memory_order::seq_cst) const volatile noexcept; // since C++20
void wait(T*, memory_order = memory_order::seq_cst) const noexcept; // since C++20
void notify_one() volatile noexcept; // since C++20
void notify_one() noexcept; // since C++20
void notify_all() volatile noexcept; // since C++20
void notify_all() noexcept; // since C++20
};

template<>
Expand Down Expand Up @@ -321,12 +321,12 @@ struct atomic<floating-point-type> { // since C++20
floating-point-type operator-=(floating-point-type) volatile noexcept;
floating-point-type operator-=(floating-point-type) noexcept;

void wait(floating-point-type, memory_order = memory_order::seq_cst) const volatile noexcept;
void wait(floating-point-type, memory_order = memory_order::seq_cst) const noexcept;
void notify_one() volatile noexcept;
void notify_one() noexcept;
void notify_all() volatile noexcept;
void notify_all() noexcept;
void wait(floating-point-type, memory_order = memory_order::seq_cst) const volatile noexcept; // since C++20
void wait(floating-point-type, memory_order = memory_order::seq_cst) const noexcept; // since C++20
void notify_one() volatile noexcept; // since C++20
void notify_one() noexcept; // since C++20
void notify_all() volatile noexcept; // since C++20
void notify_all() noexcept; // since C++20
};

// [atomics.nonmembers], non-member functions
Expand Down Expand Up @@ -443,23 +443,23 @@ template<class T>
memory_order) noexcept;

template<class T>
void atomic_wait(const volatile atomic<T>*, atomic<T>::value_type) noexcept;
void atomic_wait(const volatile atomic<T>*, atomic<T>::value_type) noexcept; // since C++20
template<class T>
void atomic_wait(const atomic<T>*, atomic<T>::value_type) noexcept;
void atomic_wait(const atomic<T>*, atomic<T>::value_type) noexcept; // since C++20
template<class T>
void atomic_wait_explicit(const volatile atomic<T>*, atomic<T>::value_type,
void atomic_wait_explicit(const volatile atomic<T>*, atomic<T>::value_type, // since C++20
memory_order) noexcept;
template<class T>
void atomic_wait_explicit(const atomic<T>*, atomic<T>::value_type,
void atomic_wait_explicit(const atomic<T>*, atomic<T>::value_type, // since C++20
memory_order) noexcept;
template<class T>
void atomic_notify_one(volatile atomic<T>*) noexcept;
void atomic_notify_one(volatile atomic<T>*) noexcept; // since C++20
template<class T>
void atomic_notify_one(atomic<T>*) noexcept;
void atomic_notify_one(atomic<T>*) noexcept; // since C++20
template<class T>
void atomic_notify_all(volatile atomic<T>*) noexcept;
void atomic_notify_all(volatile atomic<T>*) noexcept; // since C++20
template<class T>
void atomic_notify_all(atomic<T>*) noexcept;
void atomic_notify_all(atomic<T>*) noexcept; // since C++20

// Atomics for standard typedef types

Expand Down Expand Up @@ -534,12 +534,12 @@ typedef struct atomic_flag
void clear(memory_order m = memory_order_seq_cst) volatile noexcept;
void clear(memory_order m = memory_order_seq_cst) noexcept;

void wait(bool, memory_order = memory_order::seq_cst) const volatile noexcept;
void wait(bool, memory_order = memory_order::seq_cst) const noexcept;
void notify_one() volatile noexcept;
void notify_one() noexcept;
void notify_all() volatile noexcept;
void notify_all() noexcept;
void wait(bool, memory_order = memory_order::seq_cst) const volatile noexcept; // since C++20
void wait(bool, memory_order = memory_order::seq_cst) const noexcept; // since C++20
void notify_one() volatile noexcept; // since C++20
void notify_one() noexcept; // since C++20
void notify_all() volatile noexcept; // since C++20
void notify_all() noexcept; // since C++20
} atomic_flag;

bool atomic_flag_test(volatile atomic_flag* obj) noexcept;
Expand All @@ -557,14 +557,14 @@ void atomic_flag_clear(atomic_flag* obj) noexcept;
void atomic_flag_clear_explicit(volatile atomic_flag* obj, memory_order m) noexcept;
void atomic_flag_clear_explicit(atomic_flag* obj, memory_order m) noexcept;

void atomic_wait(const volatile atomic_flag* obj, T old) noexcept;
void atomic_wait(const atomic_flag* obj, T old) noexcept;
void atomic_wait_explicit(const volatile atomic_flag* obj, T old, memory_order m) noexcept;
void atomic_wait_explicit(const atomic_flag* obj, T old, memory_order m) noexcept;
void atomic_one(volatile atomic_flag* obj) noexcept;
void atomic_one(atomic_flag* obj) noexcept;
void atomic_all(volatile atomic_flag* obj) noexcept;
void atomic_all(atomic_flag* obj) noexcept;
void atomic_wait(const volatile atomic_flag* obj, T old) noexcept; // since C++20
void atomic_wait(const atomic_flag* obj, T old) noexcept; // since C++20
void atomic_wait_explicit(const volatile atomic_flag* obj, T old, memory_order m) noexcept; // since C++20
void atomic_wait_explicit(const atomic_flag* obj, T old, memory_order m) noexcept; // since C++20
void atomic_one(volatile atomic_flag* obj) noexcept; // since C++20
void atomic_one(atomic_flag* obj) noexcept; // since C++20
void atomic_all(volatile atomic_flag* obj) noexcept; // since C++20
void atomic_all(atomic_flag* obj) noexcept; // since C++20

// fences

Expand Down
10 changes: 5 additions & 5 deletions libcxx/include/barrier
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Expand Up @@ -17,7 +17,7 @@ namespace std
{

template<class CompletionFunction = see below>
class barrier
class barrier // since C++20
{
public:
using arrival_token = see below;
Expand Down Expand Up @@ -68,7 +68,7 @@ namespace std
_LIBCPP_PUSH_MACROS
# include <__undef_macros>

# if _LIBCPP_STD_VER >= 14
# if _LIBCPP_STD_VER >= 20

_LIBCPP_BEGIN_NAMESPACE_STD

Expand Down Expand Up @@ -254,7 +254,7 @@ public:
# endif // !_LIBCPP_HAS_NO_TREE_BARRIER

template <class _CompletionF = __empty_completion>
class _LIBCPP_DEPRECATED_ATOMIC_SYNC barrier {
class barrier {
__barrier_base<_CompletionF> __b_;

public:
Expand Down Expand Up @@ -290,7 +290,7 @@ public:

_LIBCPP_END_NAMESPACE_STD

# endif // _LIBCPP_STD_VER >= 14
# endif // _LIBCPP_STD_VER >= 20

_LIBCPP_POP_MACROS

Expand All @@ -305,4 +305,4 @@ _LIBCPP_POP_MACROS
# include <variant>
#endif

#endif //_LIBCPP_BARRIER
#endif // _LIBCPP_BARRIER
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