[libc++] P0355R7: Reject misused `Clock` type for which `is_clock_v<Clock>` is `false` for multi-threading components

[frederick-vs-ja]

Link: https://wg21.link/p0355r7, https://eel.is/c++draft/thread.req.paramname

Affected components:

• this_thread::sleep_until [thread.thread.this]
• timed_mutex::try_lock_until [thread.timedmutex.recursive]
• recursive_timed_mutex::try_lock_until [thread.timedmutex.recursive]
• shared_timed_mutex::try_lock_until [thread.sharedtimedmutex.class]
• shared_timed_mutex::try_lock_shared_until [thread.sharedtimedmutex.class]
• unique_lock's constructor from time_point [thread.lock.unique.cons]
• unique_lock::try_lock_until [thread.lock.unique.locking]
• shared_lock's constructor from time_point [thread.lock.shared.cons]
• shared_lock::try_lock_until [thread.lock.shared.locking]
• condition_variable::wait_until [thread.condition.condvar]
• condition_variable_any::wait_until [thread.condvarany.wait], [thread.condvarany.intwait]
• counting_semaphore::try_acquire_until [thread.sema.cnt]
• future::wait_until [futures.unique.future]
• shared_future::wait_until [futures.shared.future]

Remarks:

• We should not reject non-clock types in time_point, per P2212R2.
• is_clock_v is a C++20 feature, but most of affected components have been present before C++20. So we should either
  • guard the static_assert's with _LIBCPP_STD_VER >= 20, or
  • create an equivalent internal variable template and use it in static_assert's before C++20.

[llvmbot]

@llvm/issue-subscribers-c-20

Author: A. Jiang (frederick-vs-ja)

**Link:** https://wg21.link/p0355r7, https://eel.is/c++draft/thread.req.paramname

Affected components:

• this_thread::sleep_until [thread.thread.this]
• timed_mutex::try_lock_until [thread.timedmutex.recursive]
• recursive_timed_mutex::try_lock_until [thread.timedmutex.recursive]
• shared_timed_mutex::try_lock_until [thread.sharedtimedmutex.class]
• shared_timed_mutex::try_lock_shared_until [thread.sharedtimedmutex.class]
• unique_lock's constructor from time_point [thread.lock.unique.cons]
• unique_lock::try_lock_until [thread.lock.unique.locking]
• shared_lock's constructor from time_point [thread.lock.shared.cons]
• shared_lock::try_lock_until [thread.lock.shared.locking]
• condition_variable::wait_until [thread.condition.condvar]
• condition_variable_any::wait_until [thread.condvarany.wait], [thread.condvarany.intwait]
• counting_semaphore::try_acquire_until [thread.sema.cnt]
• future::wait_until [futures.unique.future]
• shared_future::wait_until [futures.shared.future]

Remarks:

• We should not reject non-clock types in time_point, per P2212R2.
• is_clock_v is a C++20 feature, but most of affected components have been present before C++20. So we should either
  • guard the static_assert's with _LIBCPP_STD_VER >= 20, or
  • create an equivalent internal variable template and use it in static_assert's before C++20.