As when member of Transitions::Entries that do not correspond
to rule activation (rule is empty) is either minimum or maximum
value of sys_seconds, adjusting it to std_offset lead to overflow
(and UB). In practice this caused next.when to have very low value,
and thus considered to be active rule. The to_local conversion now
return local_seconds constucted directly from time_since_epoch
(i.e. minimum and maximum).
In consequence above, the save was still not applied for zones
that specified UNTIL after firing of last rule, that aslo have
non zero save (e.g. Asia/Bishkek 2005 transition).
libstdc++-v3/ChangeLog:
PR libstdc++/116110
* src/c++20/tzdb.cc (find_active_rule::to_local): Do not
modify min/max values for rules.
* testsuite/std/time/time_zone/wall_cascade.cc: Add test
for last_transition.
---
I haven't noticed this at first, because this was not causing
any regression (the save was not applied before). Found that
while analysing output of the comparision.
For output comparision I am using a slightly different program
than your. It quries sys_info object for give time from
both libstdc++ and date, and compares abbrev, offset and save.
Then I move to time point at the end of sys_info that finished
first, and perform check again.
The above does not fail if the time range of same offset, save
and abbrev is split differently between libstdc++ and date.
(I still emit a WARN on that, but I do not think that fixing
them is necessary).
Testing on x86_64-linux. *time_zone* test passed.
OK for trunk?
libstdc++-v3/src/c++20/tzdb.cc | 13 ++--
.../std/time/time_zone/wall_cascade.cc | 73 +++++++++++++++++++
2 files changed, 81 insertions(+), 5 deletions(-)
diff --git a/libstdc++-v3/src/c++20/tzdb.cc b/libstdc++-v3/src/c++20/tzdb.cc
index e2d607dccb9..460a242fed1 100644
--- a/libstdc++-v3/src/c++20/tzdb.cc
+++ b/libstdc++-v3/src/c++20/tzdb.cc
@@ -853,12 +853,15 @@ namespace std::chrono
auto to_local = [&](const Transitions::Entry& tran, const Rule* before)
{
- local_seconds ls(tran.when.time_since_epoch() + std_offset);
- if (!before || !tran.rule)
+ local_seconds ls(tran.when.time_since_epoch());
+ if (!tran.rule)
+ // `when` is either min() or max(), and applying std_offset overflows.
return ls;
- if (tran.rule->when.indicator == at_time::Wall)
- // 'when' was converted from local time without considering
- // running 'save' in first place
+
+ ls += std_offset;
+ if (!before || tran.rule->when.indicator == at_time::Wall)
+ // no active rule or 'when' was converted from local time without
+ // considering running 'save' in first place
return ls;
return ls + before->save;
};
diff --git a/libstdc++-v3/testsuite/std/time/time_zone/wall_cascade.cc
b/libstdc++-v3/testsuite/std/time/time_zone/wall_cascade.cc
index 3529c2de852..f9167b79612 100644
--- a/libstdc++-v3/testsuite/std/time/time_zone/wall_cascade.cc
+++ b/libstdc++-v3/testsuite/std/time/time_zone/wall_cascade.cc
@@ -261,6 +261,78 @@ Z Europe/Lisbon -0:36:45 - LMT 1884
VERIFY( at_boundary.abbrev == "WET" );
}
+void
+test_last_transition()
+{
+ std::ofstream("tzdata.zi") << R"(# version test_bishkek
+R R 1984 1995 - S lastSu 2s 0 -
+R R 1985 2010 - Mar lastSu 2s 1 S
+R R 1996 2010 - O lastSu 2s 0 -
+R KG 1992 1996 - Ap Su>=7 0s 1 -
+R KG 1992 1996 - S lastSu 0 0 -
+R KG 1997 2005 - Mar lastSu 2:30 1 -
+R KG 1997 2004 - O lastSu 2:30 0 -
+Z Test/Bishkek 4:58:24 - LMT 1924 May 2
+5 R %z 1991 Au 31 2
+5 KG %z 2005 Au 12
+ )";
+
+ const auto& db = reload_tzdb();
+ VERIFY( override_used ); // If this fails then XFAIL for the target.
+ VERIFY( db.version == "test_bishkek" );
+
+ auto* tz = locate_zone("Test/Bishkek");
+
+ sys_seconds transitions[]{
+ sys_seconds{sys_days{1991y/August/30}} + 20h, // from 5 R %z 1991 Au 31 2
+ sys_seconds{sys_days{1992y/April/11}} + 19h,
+ sys_seconds{sys_days{1992y/September/26}} + 18h,
+ sys_seconds{sys_days{1993y/April/10}} + 19h,
+ sys_seconds{sys_days{1993y/September/25}} + 18h,
+ sys_seconds{sys_days{1994y/April/9}} + 19h,
+ sys_seconds{sys_days{1994y/September/24}} + 18h,
+ sys_seconds{sys_days{1995y/April/8}} + 19h,
+ sys_seconds{sys_days{1995y/September/23}} + 18h,
+ sys_seconds{sys_days{1996y/April/6}} + 19h,
+ sys_seconds{sys_days{1996y/September/28}} + 18h,
+ sys_seconds{sys_days{1997y/March/29}} + 21h + 30min,
+ sys_seconds{sys_days{1997y/October/25}} + 20h + 30min,
+ sys_seconds{sys_days{1998y/March/28}} + 21h + 30min,
+ sys_seconds{sys_days{1998y/October/24}} + 20h + 30min,
+ sys_seconds{sys_days{1999y/March/27}} + 21h + 30min,
+ sys_seconds{sys_days{1999y/October/30}} + 20h + 30min,
+ sys_seconds{sys_days{2000y/March/25}} + 21h + 30min,
+ sys_seconds{sys_days{2000y/October/28}} + 20h + 30min,
+ sys_seconds{sys_days{2001y/March/24}} + 21h + 30min,
+ sys_seconds{sys_days{2001y/October/27}} + 20h + 30min,
+ sys_seconds{sys_days{2002y/March/30}} + 21h + 30min,
+ sys_seconds{sys_days{2002y/October/26}} + 20h + 30min,
+ sys_seconds{sys_days{2003y/March/29}} + 21h + 30min,
+ sys_seconds{sys_days{2003y/October/25}} + 20h + 30min,
+ sys_seconds{sys_days{2004y/March/27}} + 21h + 30min,
+ sys_seconds{sys_days{2004y/October/30}} + 20h + 30min,
+ sys_seconds{sys_days{2005y/March/26}} + 21h + 30min,
+ sys_seconds{sys_days{2005y/August/11}} + 18h, // 5 KG %z 2005 Au 12
+ };
+
+ for (size_t i = 1; i < std::size(transitions); ++i)
+ {
+ const minutes save = (i % 2) ? 0h : 1h;
+ const sys_seconds t = transitions[i-1];
+ const sys_info info = tz->get_info(t);
+ VERIFY( info.begin == t );
+ VERIFY( info.offset == 5h + save );
+ VERIFY( info.save == save );
+ VERIFY( info.end == transitions[i] );
+ }
+
+ // The transition 2005 Au 12 has total offset 6 (5h + 1h).
+ sys_seconds t = transitions[std::size(transitions)-1];
+ const sys_info info = tz->get_info(t);
+ VERIFY( info.offset == 6h );
+ VERIFY( info.save == 1h );
+}
+
int
main()
{
@@ -270,4 +342,5 @@ main()
test_prev_year();
test_earlier_year();
test_at_boundary();
+ test_last_transition();
}
--
2.55.0
