Issue 3499: Timed lockable and mutex requirements are imprecise about duration and time

3499. Timed lockable and mutex requirements are imprecise about `duration` and `time_point`

Section: 32.2.5.4 [thread.req.lockable.timed], 32.6.4.3 [thread.timedmutex.requirements] Status: New Submitter: Tim Song Opened: 2020-11-14 Last modified: 2020-11-21

Priority: 3

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Discussion:

The timed lockable and mutex requirements currently use "rel_time denotes an object of an instantiation of duration, and abs_time denotes an object of an instantiation of time_point" to define the variables used to specify the timed lock functions. During LWG review of P2160R0, it was noted that this definition is deficient in two aspects:

It doesn't allow for cv-qualification of rel_time and abs_time
For time_points, it should require that the clock is a real Cpp17Clock. We impose that requirement via 32.2.1 [thread.req.paramname], but there are no template parameters named Clock here.

[2020-11-21; Reflector prioritization]

Set priority to 3 during reflector discussions.

Proposed resolution:

3499. Timed lockable and mutex requirements are imprecise about duration and time_point

3499. Timed lockable and mutex requirements are imprecise about `duration` and `time_point`