Breakdown the "seconds + femtoseconds => time_point" overflow issue. #200
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When `cctz::parse()` produces seconds+femtoseconds values that cannot be represented in the output `time_point<D>` it should return `false`. Here we add overloads of `join_seconds()` that break the overflow issue down into four cases, three of which are implemented and have test cases. The fourth overload (for 1/N duration ratios) is yet to be implemented, so its test cases are currently commented out, but they provide a guide to what remains to be done. See google#199. Also, clarify that the `ToUnixSeconds()` implementation requires that the `std::chrono::system_clock` uses the Unix epoch in order to avoid arithmetic overflow.
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When
cctz::parse()produces seconds+femtoseconds values that cannotbe represented in the output
time_point<D>it should returnfalse.Here we add overloads of
join_seconds()that break the overflow issuedown into four cases, three of which are implemented and have test cases.
The fourth overload (for 1/N duration ratios) is yet to be implemented,
so its test cases are currently commented out, but they provide a guide
to what remains to be done. See #199.
Also, clarify that the
ToUnixSeconds()implementation requires thatthe
std::chrono::system_clockuses the Unix epoch in order to avoidarithmetic overflow.
This change is