This is a partial fix for PR 116110, so that zone changes that occur at
a time specified as standard time will be parsed correctly. Previously
all UNTIL times were assumed to be UTC, which is incorrect according to
the spec. Only times with a 'u' suffix (or the equivalent 'g' or 'z')
are UTC times. An 's' suffix means standard time (i.e. the zone's usual
offset from UTC, without any DST adjustment) and a 'w' suffix (or no
suffix) means wall time, so the offset and any DST adjustment. This
commit fixes the handling of 's' suffixes, so that the ZoneInfo::m_until
member is set correctly. It also fixes the handling of some UNTIL times
using wall time, specifically those where the DST adjustment is known
during parsing of the tzdata.zi file.
This is not a complete fix, because as noted in PR 116110 a Zone line
that refers to a named Rule and uses wall time cannot be determined
while parsing tzdata.zi. We need to remember that the m_until member is
not correct, and then adjust it later when we find the rule that applies
at a given time point. That requires more work.
Some existing tests need to be adjusted due to the fixes in this commit.
The std/time/time_zone/get_info_sys.cc and std/time/zoned_time/1.cc
tests are corrected to check that the changes happens at midnight local
time, not midnight UTC as previously assumed.
libstdc++-v3/ChangeLog:
PR libstdc++/116110
* src/c++20/tzdb.cc (operator>>(istream&, ZoneInfo&)): Adjust
inf.m_until according to indicator suffix on AT time in UNTIL.
* testsuite/std/time/time_zone/get_info_sys.cc: Adjust expected
results to account for corrected logic.
* testsuite/std/time/zoned_time/1.cc: Likewise.
---
Tested x86_64-linux.
libstdc++-v3/src/c++20/tzdb.cc | 15 +++++++++----
.../std/time/time_zone/get_info_sys.cc | 22 +++++++++++--------
.../testsuite/std/time/zoned_time/1.cc | 20 ++++++++++-------
3 files changed, 36 insertions(+), 21 deletions(-)
diff --git a/libstdc++-v3/src/c++20/tzdb.cc b/libstdc++-v3/src/c++20/tzdb.cc
index e26a9ee38072..82e4790b0d7f 100644
--- a/libstdc++-v3/src/c++20/tzdb.cc
+++ b/libstdc++-v3/src/c++20/tzdb.cc
@@ -2289,11 +2289,18 @@ namespace std::chrono
at_time t{};
// XXX DAY should support ON format, e.g. lastSun or Sun>=8
in >> m >> d >> t;
- // XXX UNTIL field should be interpreted
- // "using the rules in effect just before the transition"
- // so might need to store as year_month_day and hh_mm_ss and only
- // convert to a sys_time once we know the offset in effect.
inf.m_until = sys_days(year(y)/m.m/day(d)) + seconds(t.time);
+ if (t.indicator != at_time::Universal)
+ { // UNTIL uses "the rules in effect just before the transition"
+ // adjust by STDOFF
+ inf.m_until -= seconds(inf.m_offset);
+ if (t.indicator != at_time::Standard)
+ {
+ if (inf.m_expanded) // Not a named Rule, SAVE is known now.
+ inf.m_until -= inf.m_save;
+ // else Named Rule, SAVE is unknown. FIXME: PR 116110
+ }
+ }
}
else
inf.m_until = sys_days(year::max()/December/31);
diff --git a/libstdc++-v3/testsuite/std/time/time_zone/get_info_sys.cc
b/libstdc++-v3/testsuite/std/time/time_zone/get_info_sys.cc
index 769c7744017b..88f16b76ff48 100644
--- a/libstdc++-v3/testsuite/std/time/time_zone/get_info_sys.cc
+++ b/libstdc++-v3/testsuite/std/time/time_zone/get_info_sys.cc
@@ -12,33 +12,37 @@ test_zurich()
const time_zone* const tz = locate_zone("Europe/Zurich");
{
- sys_days d = 1853y/July/16;
+ sys_days d = 1853y/July/16; // On this date ...
+ auto offset = 34min + 8s; // ... local time is this far ahead of UTC,
+ auto t = d - offset; // so LMT to BMT transition is at this time.
- auto info = tz->get_info(d - 1s);
- VERIFY( info.offset == (34min + 8s) );
+ auto info = tz->get_info(t - 1s);
+ VERIFY( info.offset == offset );
VERIFY( info.abbrev == "LMT" );
- info = tz->get_info(d);
+ info = tz->get_info(t);
VERIFY( info.offset == (29min + 46s) );
VERIFY( info.abbrev == "BMT" );
- info = tz->get_info(d + 1s);
+ info = tz->get_info(t + 1s);
VERIFY( info.offset == (29min + 46s) );
VERIFY( info.abbrev == "BMT" );
- info = tz->get_info(d + 0.001s);
+ info = tz->get_info(t + 0.001s);
VERIFY( info.offset == (29min + 46s) );
VERIFY( info.abbrev == "BMT" );
}
{
sys_days d = 1894y/June/1;
+ auto offset = 29min + 46s;
+ auto t = d - offset;
- auto info = tz->get_info(d - 1s);
- VERIFY( info.offset == (29min + 46s) );
+ auto info = tz->get_info(t - 1s);
+ VERIFY( info.offset == offset );
VERIFY( info.abbrev == "BMT" );
- info = tz->get_info(d);
+ info = tz->get_info(t);
VERIFY( info.offset == 1h );
VERIFY( info.abbrev == "CET" );
}
diff --git a/libstdc++-v3/testsuite/std/time/zoned_time/1.cc
b/libstdc++-v3/testsuite/std/time/zoned_time/1.cc
index 1623aca1c7a8..a77cd99dd550 100644
--- a/libstdc++-v3/testsuite/std/time/zoned_time/1.cc
+++ b/libstdc++-v3/testsuite/std/time/zoned_time/1.cc
@@ -48,24 +48,26 @@ test_zurich()
const time_zone* const zurich = locate_zone("Europe/Zurich");
{
- sys_days d = 1853y/July/16;
+ sys_days d = 1853y/July/16; // On this date ...
+ auto offset = 34min + 8s; // ... local time is this far ahead of UTC,
+ auto t = d - offset; // so LMT to BMT transition is at this time.
- auto z = zoned_seconds(zurich, sys_seconds(d) - 1s);
+ auto z = zoned_seconds(zurich, t - 1s);
auto info = z.get_info();
- VERIFY( info.offset == (34min + 8s) );
+ VERIFY( info.offset == offset );
VERIFY( info.abbrev == "LMT" );
- z = zoned_seconds(zurich, d);
+ z = zoned_seconds(zurich, t);
info = z.get_info();
VERIFY( info.offset == (29min + 46s) );
VERIFY( info.abbrev == "BMT" );
- z = zoned_seconds(zurich, d + 1s);
+ z = zoned_seconds(zurich, t + 1s);
info = z.get_info();
VERIFY( info.offset == (29min + 46s) );
VERIFY( info.abbrev == "BMT" );
- auto z2 = zoned_time(zurich, d + 0.001s);
+ auto z2 = zoned_time(zurich, t + 0.001s);
info = z2.get_info();
VERIFY( info.offset == (29min + 46s) );
VERIFY( info.abbrev == "BMT" );
@@ -73,13 +75,15 @@ test_zurich()
{
sys_days d = 1894y/June/1;
+ auto offset = 29min + 46s;
+ auto t = d - offset;
- auto z = zoned_seconds(zurich, sys_seconds(d) - 1s);
+ auto z = zoned_seconds(zurich, t - 1s);
auto info = z.get_info();
VERIFY( info.offset == (29min + 46s) );
VERIFY( info.abbrev == "BMT" );
- z = zoned_seconds(zurich, d);
+ z = zoned_seconds(zurich, t);
info = z.get_info();
VERIFY( info.offset == 1h );
VERIFY( info.abbrev == "CET" );
--
2.53.0
