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<chrono>: Properly handle duration with unsigned rep when formatting #5947

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Merged
Stephan T. Lavavej (StephanTLavavej) merged 1 commit into from
Dec 8, 2025
Merged

<chrono>: Properly handle duration with unsigned rep when formatting #5947

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6 changes: 5 additions & 1 deletion stl/inc/chrono
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Original file line number Diff line number Diff line change
Expand Up @@ -5612,7 +5612,11 @@ namespace chrono {
return true;
case 'Q':
if constexpr (_Is_specialization_v<_Ty, duration>) {
_Os << _STD abs(_Val.count());
if constexpr (is_unsigned_v<typename _Ty::rep>) {
_Os << _Val.count();
} else {
_Os << _STD abs(_Val.count());
}
} else {
_STL_INTERNAL_CHECK(false);
}
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27 changes: 27 additions & 0 deletions tests/std/tests/P0355R7_calendars_and_time_zones_formatting/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
#include <timezone_data.hpp>

// Extended to test LWG-4257 "Stream insertion for chrono::local_time should be constrained"
// Extended to test GH-5945 "<chrono>: cannot format unsigned durations"

using namespace std;
using namespace chrono;
Expand Down Expand Up @@ -286,6 +287,11 @@ void test_duration_formatter() {
assert(format(STR("{:%T %j}"), duration<float, days::period>{1.55f}) == STR("37:11:59 1"));
assert(format(STR("{:%T %j}"), duration<float, days::period>{-1.55f}) == STR("-37:11:59 1"));

// GH-5945 "<chrono>: cannot format unsigned durations"
assert(format(STR("{:%T %j %q %Q}"), duration<unsigned long long, days::period>{4} + 30min)
== STR("96:30:00 4 min 5790"));
assert(format(STR("{:%T %j}"), duration<unsigned long long, days::period>{4} + 23h + 30min) == STR("119:30:00 4"));

// GH-4247: <chrono>: format() should accept %X and %EX for duration and hh_mm_ss
assert(format(STR("{:%X}"), 9h + 7min + 5s) == STR("09:07:05"));
assert(format(STR("{:%EX}"), 9h + 7min + 5s) == STR("09:07:05"));
Expand Down Expand Up @@ -1102,8 +1108,29 @@ void check_stream_insertion_operator() {
check_stream_insertion_operator_for_duration<bad_dur>();
}

// Test introduced for GH-5945 "<chrono>: cannot format unsigned durations"
void test_format_duration_with_unsigned_rep() {
// operator<<(ostream&, duration _Dur) only prints _Dur.count() (does not use abs)
{
ostringstream oss;
oss << duration<unsigned long, nano>{3};
assert(oss.str() == "3ns");
}
{
ostringstream oss;
oss << duration<long, nano>{-3};
assert(oss.str() == "-3ns");
}

// format calls abs under the hood when needed, this would be rejected before fix.
assert(format("{}", duration<long, nano>{-3}) == "-3ns");
assert(format("{}", duration<unsigned long, nano>{3}) == "3ns");
assert(format("{:%Q}", duration<unsigned long, nano>{3}) == "3");
}

void test() {
test_unsigned_sys_time_format_after_LWG_4274();
test_format_duration_with_unsigned_rep();

check_stream_insertion_operator();

Expand Down