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[libc++][chrono] Fixes leap seconds. #90070

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merged 1 commit into from
Jul 4, 2024
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[libc++][chrono] Fixes leap seconds. #90070

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2 changes: 1 addition & 1 deletion libcxx/docs/Status/Cxx20Issues.csv
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Original file line number Diff line number Diff line change
Expand Up @@ -269,7 +269,7 @@
"`3355 <https://wg21.link/LWG3355>`__","The memory algorithms should support move-only input iterators introduced by P1207","Prague","|Complete|","15.0","|ranges|"
"`3356 <https://wg21.link/LWG3356>`__","``__cpp_lib_nothrow_convertible``\ should be ``__cpp_lib_is_nothrow_convertible``\ ","Prague","|Complete|","12.0"
"`3358 <https://wg21.link/LWG3358>`__","|sect|\ [span.cons] is mistaken that ``to_address``\ can throw","Prague","|Complete|","17.0"
"`3359 <https://wg21.link/LWG3359>`__","``<chrono>``\ leap second support should allow for negative leap seconds","Prague","|Complete|","19.0","|chrono|"
"`3359 <https://wg21.link/LWG3359>`__","``<chrono>``\ leap second support should allow for negative leap seconds","Prague","|In Progress|","","|chrono|"
"`3360 <https://wg21.link/LWG3360>`__","``three_way_comparable_with``\ is inconsistent with similar concepts","Prague","|Nothing To Do|","","|spaceship|"
"`3362 <https://wg21.link/LWG3362>`__","Strike ``stop_source``\ 's ``operator!=``\ ","Prague","",""
"`3363 <https://wg21.link/LWG3363>`__","``drop_while_view``\ should opt-out of ``sized_range``\ ","Prague","|Nothing To Do|","","|ranges|"
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64 changes: 40 additions & 24 deletions libcxx/src/tzdb.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -626,29 +626,49 @@ static void __parse_leap_seconds(vector<leap_second>& __leap_seconds, istream&&
// seconds since 1 January 1970.
constexpr auto __offset = sys_days{1970y / January / 1} - sys_days{1900y / January / 1};

while (true) {
switch (__input.peek()) {
case istream::traits_type::eof():
return;

case ' ':
case '\t':
case '\n':
__input.get();
continue;
struct __entry {
sys_seconds __timestamp;
seconds __value;
};
vector<__entry> __entries;
[&] {
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What's the purpose of wrapping the loop in an IILE?

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In the while loop there is a switch that should terminate the processing when EOF is found. Since test is in a switch I can't use break. Using a IILE allows to use return. Refactoring this lambda to a function doesn't improve code readability, so I prefer an IILE.

while (true) {
switch (__input.peek()) {
case istream::traits_type::eof():
return;

case ' ':
case '\t':
case '\n':
__input.get();
continue;

case '#':
chrono::__skip_line(__input);
continue;
}

case '#':
sys_seconds __date = sys_seconds{seconds{chrono::__parse_integral(__input, false)}} - __offset;
chrono::__skip_mandatory_whitespace(__input);
seconds __value{chrono::__parse_integral(__input, false)};
chrono::__skip_line(__input);
continue;
}

sys_seconds __date = sys_seconds{seconds{chrono::__parse_integral(__input, false)}} - __offset;
chrono::__skip_mandatory_whitespace(__input);
seconds __value{chrono::__parse_integral(__input, false)};
chrono::__skip_line(__input);

__leap_seconds.emplace_back(std::__private_constructor_tag{}, __date, __value);
}
__entries.emplace_back(__date, __value);
}
}();
// The Standard requires the leap seconds to be sorted. The file
// leap-seconds.list usually provides them in sorted order, but that is not
// guaranteed so we ensure it here.
ranges::sort(__entries, {}, &__entry::__timestamp);

// The database should contain the number of seconds inserted by a leap
// second (1 or -1). So the difference between the two elements is stored.
// std::ranges::views::adjacent has not been implemented yet.
(void)ranges::adjacent_find(__entries, [&](const __entry& __first, const __entry& __second) {
__leap_seconds.emplace_back(
std::__private_constructor_tag{}, __second.__timestamp, __second.__value - __first.__value);
return false;
});
}

void __init_tzdb(tzdb& __tzdb, __tz::__rules_storage_type& __rules) {
Expand All @@ -667,10 +687,6 @@ void __init_tzdb(tzdb& __tzdb, __tz::__rules_storage_type& __rules) {
// The latter is much easier to parse, it seems Howard shares that
// opinion.
chrono::__parse_leap_seconds(__tzdb.leap_seconds, ifstream{__root / "leap-seconds.list"});
// The Standard requires the leap seconds to be sorted. The file
// leap-seconds.list usually provides them in sorted order, but that is not
// guaranteed so we ensure it here.
std::ranges::sort(__tzdb.leap_seconds);
}

#ifdef _WIN32
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23 changes: 15 additions & 8 deletions libcxx/test/libcxx/time/time.zone/time.zone.db/leap_seconds.pass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -83,32 +83,39 @@ static void test_leap_seconds() {
2303683200 12 # 1 Jan 1973
2287785600 11 # 1 Jul 1972
2272060800 10 # 1 Jan 1972
86400 1 # 2 Jan 1900 Dummy entry to test before 1970
86400 9 # 2 Jan 1900 Dummy entry to test before 1970
1 8 # 2 Jan 1900 Dummy entry to test before 1970

# Fictional negative leap second
2303769600 11 # 2 Jan 1973

# largest accepted value by the parser
5764607523034234879 2
5764607523034234879 12
)");

assert(result.leap_seconds.size() == 5);
assert(result.leap_seconds.size() == 6);

assert(result.leap_seconds[0].date() == sys_seconds{sys_days{1900y / January / 2}});
assert(result.leap_seconds[0].value() == 1s);

assert(result.leap_seconds[1].date() == sys_seconds{sys_days{1972y / January / 1}});
assert(result.leap_seconds[1].value() == 10s);
assert(result.leap_seconds[1].value() == 1s);

assert(result.leap_seconds[2].date() == sys_seconds{sys_days{1972y / July / 1}});
assert(result.leap_seconds[2].value() == 11s);
assert(result.leap_seconds[2].value() == 1s);

assert(result.leap_seconds[3].date() == sys_seconds{sys_days{1973y / January / 1}});
assert(result.leap_seconds[3].value() == 12s);
assert(result.leap_seconds[3].value() == 1s);

assert(result.leap_seconds[4].date() == sys_seconds{sys_days{1973y / January / 2}});
assert(result.leap_seconds[4].value() == -1s);

assert(result.leap_seconds[4].date() ==
assert(result.leap_seconds[5].date() ==
sys_seconds{5764607523034234879s
// The database uses 1900-01-01 as epoch.
- std::chrono::duration_cast<std::chrono::seconds>(
sys_days{1970y / January / 1} - sys_days{1900y / January / 1})});
assert(result.leap_seconds[4].value() == 2s);
assert(result.leap_seconds[5].value() == 1s);
}

int main(int, const char**) {
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55 changes: 27 additions & 28 deletions libcxx/test/std/time/time.zone/time.zone.db/leap_seconds.pass.cpp
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Expand Up @@ -33,34 +33,33 @@ using namespace std::literals::chrono_literals;
// At the moment of writing that list is the actual list in the IANA database.
// If in the future more leap seconds can be added.
static const std::array leap_seconds = {
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1972y / std::chrono::January / 1}}, 10s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1972y / std::chrono::July / 1}}, 11s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1973y / std::chrono::January / 1}}, 12s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1974y / std::chrono::January / 1}}, 13s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1975y / std::chrono::January / 1}}, 14s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1976y / std::chrono::January / 1}}, 15s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1977y / std::chrono::January / 1}}, 16s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1978y / std::chrono::January / 1}}, 17s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1979y / std::chrono::January / 1}}, 18s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1980y / std::chrono::January / 1}}, 19s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1981y / std::chrono::July / 1}}, 20s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1982y / std::chrono::July / 1}}, 21s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1983y / std::chrono::July / 1}}, 22s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1985y / std::chrono::July / 1}}, 23s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1988y / std::chrono::January / 1}}, 24s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1990y / std::chrono::January / 1}}, 25s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1991y / std::chrono::January / 1}}, 26s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1992y / std::chrono::July / 1}}, 27s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1993y / std::chrono::July / 1}}, 28s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1994y / std::chrono::July / 1}}, 29s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1996y / std::chrono::January / 1}}, 30s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1997y / std::chrono::July / 1}}, 31s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1999y / std::chrono::January / 1}}, 32s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2006y / std::chrono::January / 1}}, 33s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2009y / std::chrono::January / 1}}, 34s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2012y / std::chrono::July / 1}}, 35s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2015y / std::chrono::July / 1}}, 36s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2017y / std::chrono::January / 1}}, 37s)};
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1972y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1973y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1974y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1975y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1976y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1977y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1978y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1979y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1980y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1981y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1982y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1983y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1985y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1988y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1990y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1991y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1992y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1993y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1994y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1996y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1997y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{1999y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2006y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2009y / std::chrono::January / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2012y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2015y / std::chrono::July / 1}}, 1s),
std::make_pair(std::chrono::sys_seconds{std::chrono::sys_days{2017y / std::chrono::January / 1}}, 1s)};

int main(int, const char**) {
const std::chrono::tzdb& tzdb = std::chrono::get_tzdb();
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