f4a52c184d
Implementing all chrono::from_stream overloads in terms of chrono::sys_time meant that a leap second time like 23:59:60.001 cannot be parsed, because that cannot be represented in a sys_time. The fix to support parsing leap seconds as utc_time is to convert the parsed date to utc_time<days> and then add the parsed time to that, which allows the result to land in a leap second, rather than doing all the arithmetic with sys_time which doesn't have leap seconds. For local_time we also allow %S to parse a 60s value, because doing otherwise might disallow some valid uses. We can't know all use cases users have for treating times as local_time. For all other clocks, we can reject times that have 60 or 60.nnn as the seconds part, because that cannot occur in a valid UNIX, GPS, or TAI time. Since our chrono::file_clock uses sys_time, it can't occur for that clock either. In order to support this a new _M_is_leap_second member is needed in the _Parser type. This can be added at the end, where most targets currently have padding bytes. Similar to what I did recently for formatter _Spec structs, we can also reserve additional padding bits for future expansion. This also fixes bugs in the from_stream overloads for utc_time, tai_time, gps_time, and file_time, which were not using time_point_cast to explicitly convert to the result type. That's needed because the result type might have lower precision than the value returned from from_sys or from_utc, which has a precision no lower than seconds. libstdc++-v3/ChangeLog: PR libstdc++/114279 * include/bits/chrono_io.h (_Parser::_M_is_leap_second): New data member. (_Parser::_M_reserved): Reserve padding bits for future use. (_Parser::operator()): Set _M_is_leap_second if %S reads 60s. (from_stream): Only allow _M_is_leap_second for utc_time and local_time. Adjust arithmetic for utc_time so that leap seconds are preserved. Use time_point_cast to convert to a possibly lower-precision result type. * testsuite/std/time/parse.cc: Move to ... * testsuite/std/time/parse/parse.cc: ... here. * testsuite/std/time/parse/114279.cc: New test.
53 lines
1.4 KiB
C++
53 lines
1.4 KiB
C++
// { dg-do run { target c++20 } }
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#include <chrono>
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#include <sstream>
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#include <testsuite_hooks.h>
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template<class Clock>
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void
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test_leap_second_parsing()
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{
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std::chrono::time_point<Clock, std::chrono::milliseconds> tp, tp2;
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std::istringstream ss("20161231-23:59:60.05");
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ss >> std::chrono::parse("%Y%m%d-%T", tp);
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if constexpr (std::is_same_v<Clock, std::chrono::local_t>)
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VERIFY( ss ); // We allow parsing "23:59:60" as local_time.
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else
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{
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if constexpr (std::is_same_v<Clock, std::chrono::utc_clock>)
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{
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// Entire input was consumed.
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VERIFY( ss );
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VERIFY( ss.eof() );
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// The parsed value is the leap second inserted on Jan 1 2017.
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VERIFY( std::chrono::get_leap_second_info(tp).is_leap_second );
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}
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else
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VERIFY( !ss ); // Other clocks do not allow "HH:MM:60"
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ss.clear();
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ss.str("20161231-22:59:60.05 -0100"); // Same time at -1h offset.
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ss >> std::chrono::parse("%Y%m%d-%T %z", tp2);
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if constexpr (std::is_same_v<Clock, std::chrono::utc_clock>)
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{
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VERIFY( ss );
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VERIFY( tp2 == tp );
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}
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else
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VERIFY( !ss );
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}
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}
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int main()
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{
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test_leap_second_parsing<std::chrono::system_clock>();
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test_leap_second_parsing<std::chrono::utc_clock>();
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test_leap_second_parsing<std::chrono::tai_clock>();
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test_leap_second_parsing<std::chrono::gps_clock>();
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test_leap_second_parsing<std::chrono::file_clock>();
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test_leap_second_parsing<std::chrono::local_t>();
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}
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