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[libc++][TZDB] Fixes mapping of nonexisting time. (#127330)

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All non-existing local times in a contiguous range should map to the
same time point. This fixes a bug, were the times inside the range were
mapped to the wrong time.

Fixes: #113654
This commit is contained in:
Mark de Wever 2025-02-17 19:08:07 +01:00 committed by GitHub
parent 74656476b8
commit 941f7cbf5a
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GPG Key ID: B5690EEEBB952194
2 changed files with 21 additions and 4 deletions
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8
libcxx/include/__chrono/time_zone.h
View File

@ -103,10 +103,14 @@ public:
to_sys(const local_time<_Duration>& __time, choose __z) const {
local_info __info = get_info(__time);
switch (__info.result) {
case local_info::unique:
case local_info::nonexistent: // first and second are the same
case local_info::unique: // first and second are the same
return sys_time<common_type_t<_Duration, seconds>>{__time.time_since_epoch() - __info.first.offset};
case local_info::nonexistent:
// first and second are the same
// All non-existing values are converted to the same time.
return sys_time<common_type_t<_Duration, seconds>>{__info.first.end};
case local_info::ambiguous:
switch (__z) {
case choose::earliest:

17
libcxx/test/std/time/time.zone/time.zone.timezone/time.zone.members/to_sys_choose.pass.cpp
View File

@ -88,7 +88,7 @@ static void test_nonexistent() {
// Pick an historic date where it's well known what the time zone rules were.
// This makes it unlikely updates to the database change these rules.
std::chrono::local_time<std::chrono::seconds> time{
(std::chrono::sys_days{std::chrono::March / 30 / 1986} + 2h + 30min).time_since_epoch()};
(std::chrono::sys_days{std::chrono::March / 30 / 1986} + 2h).time_since_epoch()};
std::chrono::sys_seconds expected{time.time_since_epoch() - 1h};
@ -100,6 +100,13 @@ static void test_nonexistent() {
assert(tz->to_sys(time + 0us, std::chrono::choose::latest) == expected);
assert(tz->to_sys(time + 0ms, std::chrono::choose::earliest) == expected);
assert(tz->to_sys(time + 0s, std::chrono::choose::latest) == expected);
// The entire nonexisting hour should map to the same time.
// For nonexistant the value of std::chrono::choose has no effect.
assert(tz->to_sys(time + 1s, std::chrono::choose::earliest) == expected);
assert(tz->to_sys(time + 1min, std::chrono::choose::latest) == expected);
assert(tz->to_sys(time + 30min, std::chrono::choose::earliest) == expected);
assert(tz->to_sys(time + 59min + 59s, std::chrono::choose::latest) == expected);
}
// Tests ambiguous conversions.
@ -120,7 +127,7 @@ static void test_ambiguous() {
// Pick an historic date where it's well known what the time zone rules were.
// This makes it unlikely updates to the database change these rules.
std::chrono::local_time<std::chrono::seconds> time{
(std::chrono::sys_days{std::chrono::September / 28 / 1986} + 2h + 30min).time_since_epoch()};
(std::chrono::sys_days{std::chrono::September / 28 / 1986} + 2h).time_since_epoch()};
std::chrono::sys_seconds earlier{time.time_since_epoch() - 2h};
std::chrono::sys_seconds later{time.time_since_epoch() - 1h};
@ -133,6 +140,12 @@ static void test_ambiguous() {
assert(tz->to_sys(time + 0us, std::chrono::choose::latest) == later);
assert(tz->to_sys(time + 0ms, std::chrono::choose::earliest) == earlier);
assert(tz->to_sys(time + 0s, std::chrono::choose::latest) == later);
// Test times in the ambigious hour
assert(tz->to_sys(time + 1s, std::chrono::choose::earliest) == earlier + 1s);
assert(tz->to_sys(time + 1min, std::chrono::choose::latest) == later + 1min);
assert(tz->to_sys(time + 30min, std::chrono::choose::earliest) == earlier + 30min);
assert(tz->to_sys(time + 59min + 59s, std::chrono::choose::latest) == later + 59min + 59s);
}
// This test does the basic validations of this function. The library function