How do robust clocks interact with time-limited bit representations?

Question

11.20.7.2/1 begins:

The objects of the steady_clock class represent a clock for which time_point values ​​never decrease as physical time and for which time_point values ​​advance at a steady speed relative to real time. That is, the clock may not be adjusted.

In concept, this is fine, but given that there will almost certainly be a limited number of bits to represent a point in time, it is difficult to imagine an implementation where the constant value of the clock simply increases forever.

11/20/3 / 2 seems to support my lack of imagination, because it refers (in a non-normative note) to a watch that "wraps". This suggests that if I have time_point t1 and later time_point t2 taken from the same constant clock, t2 may appear ahead of time because the clock can be wrapped between t1 and t2 .

It is very difficult for me to understand the standard in this area. Can anyone give clarity about the relationship and interaction of the constant clock and the wrap of the clock?

Answer 1

Please send an error report when you are really watching the steady_clock transition. On my system, if I do not restart the computer within the next 292 years, this will happen in 2305. Sorry if I will not answer at this time. :-)

Leaning to the side, implementation is necessary to support a sufficiently large bit length, so that clock scrolling cannot be observed during practical time. It is believed that nanoseconds in a 64-bit integer from the moment the computer boots up are one reasonable implementation of this.