Defined in header <chrono>
template <class Dest, class Source, class Duration> (since
C++20)
auto clock_cast(const std::chrono::time_point<Source, Duration>&
t);
Converts the time point t of a clock Source to an equivalent time point of
the clock
Dest, using std::chrono::system_clock and/or std::chrono::utc_clock as
intermediaries if necessary.
* If the expression std::chrono::clock_time_conversion<Dest,
Source>{}(t) is
well-formed, returns the result of that expression.
* Otherwise, if at least one of the following two expressions are
well-formed,
then
* If both expressions are well-formed, the conversion is ambiguous, and
the program is ill-formed.
* Otherwise, exactly one of the two expressions is well-formed; the
result of that expression is returned.
1) std::chrono::clock_time_conversion<Dest,
std::chrono::system_clock>{}(
std::chrono::clock_time_conversion<std::chrono::system_clock,
Source>{}(t))
2) std::chrono::clock_time_conversion<Dest, std::chrono::utc_clock>{}(
std::chrono::clock_time_conversion<std::chrono::utc_clock,
Source>{}(t))
* Otherwise, if at least one of the following two expressions are
well-formed,
then
* If both expressions are well-formed, the conversion is ambiguous, and
the program is ill-formed.
* Otherwise, exactly one of the two expressions is well-formed; the
result of that expression is returned.
1) std::chrono::clock_time_conversion<Dest,
std::chrono::utc_clock>{}(
std::chrono::clock_time_conversion<std::chrono::utc_clock,
std::chrono::system_clock>{}(
std::chrono::clock_time_conversion<std::chrono::system_clock,
Source>{}(t)))
2) std::chrono::clock_time_conversion<Dest,
std::chrono::system_clock>{}(
std::chrono::clock_time_conversion<std::chrono::system_clock,
std::chrono::utc_clock>{}(
std::chrono::clock_time_conversion<std::chrono::utc_clock,
Source>{}(t)))
* Otherwise, this function does not participate in overload resolution.