Returns:
A time_t object that represents the same point in time as t
when both values are restricted to the coarser of the precisions of time_t and
time_point.

It is implementation-defined
whether values are rounded or truncated to the required precision.

Returns:
A time_point object that represents the same point in time as t
when both values are restricted to the coarser of the precisions of time_t and
time_point.

It is implementation-defined
whether values are rounded or truncated to the required precision.