std::chrono::clock_cast

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Defined in header`<chrono>`
template<class Dest,class Source,class Duration> auto clock_cast(conststd::chrono::time_point<Source, Duration>& t);		(since C++20)

Converts the time pointt of a clockSource to an equivalent time point of the clockDest, usingstd::chrono::system_clock and/orstd::chrono::utc_clock as intermediaries if necessary.

If the expressionstd::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.