Tested x86_64-linux. Pushed to trunk.
-- >8 --
When formatting with an empty chrono spec ("{}") two minus signs were
being added to hh_mm_ss values. This is because the __is_neg flag was
checked to add one explicitly, and then the ostream operator added
another one.
We should only check the __is_neg flag for durations, because those are
the only types which are modified to be non-negative before calling
_M_format. We don't change hh_mm_ss values to be negative, because that
would require performing arithmetic on the hh_mm_ss members to sum them,
and then again to construct a new hh_mm_ss object with the positive
value. Instead, we can just be careful about using the __is_neg flag
correctly.
To fix the bug, _M_format_to_ostream no longer checks the __is_neg flag
for non-durations, and _M_format doesn't set it for hh_mm_ss until after
the call to _M_format_to_ostream. We can also avoid setting it for types
that it doesn't apply to, by making the __print_sign lambda only inspect
it for duration and hh_mm_ss types.
libstdc++-v3/ChangeLog:
* include/bits/chrono_io.h (__formatter_chrono::_M_format):
Do not set __is_neg for hh_mm_ss before calling
_M_format_to_ostream. Change __print_sign lambda to only check
__is_neg for durations and hh_mm_ss types.
(__formatter_chrono::_M_format_to_ostream): Only check __is_neg
for duration types.
* testsuite/std/time/hh_mm_ss/io.cc: Check negative values.
---
libstdc++-v3/include/bits/chrono_io.h | 27 ++++++++++---------
.../testsuite/std/time/hh_mm_ss/io.cc | 4 +++
2 files changed, 19 insertions(+), 12 deletions(-)
diff --git a/libstdc++-v3/include/bits/chrono_io.h
b/libstdc++-v3/include/bits/chrono_io.h
index 0c5f9f5058b..c95301361d8 100644
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -486,11 +486,6 @@ namespace __format
_M_format(const _Tp& __t, _FormatContext& __fc,
bool __is_neg = false) const
{
- if constexpr (__is_specialization_of<_Tp, chrono::hh_mm_ss>)
- __is_neg = __t.is_negative();
- else if constexpr (!chrono::__is_duration_v<_Tp>)
- __is_neg = false;
-
auto __first = _M_spec._M_chrono_specs.begin();
const auto __last = _M_spec._M_chrono_specs.end();
if (__first == __last)
@@ -513,12 +508,19 @@ namespace __format
else
__out = __sink.out();
+ // formatter<duration> passes the correct value of __is_neg
+ // for durations but for hh_mm_ss we decide it here.
+ if constexpr (__is_specialization_of<_Tp, chrono::hh_mm_ss>)
+ __is_neg = __t.is_negative();
+
auto __print_sign = [&__is_neg, &__out] {
- if (__is_neg)
- {
- *__out++ = _S_plus_minus[1];
- __is_neg = false;
- }
+ if constexpr (chrono::__is_duration_v<_Tp>
+ || __is_specialization_of<_Tp, chrono::hh_mm_ss>)
+ if (__is_neg)
+ {
+ *__out++ = _S_plus_minus[1];
+ __is_neg = false;
+ }
return std::move(__out);
};
@@ -708,8 +710,9 @@ namespace __format
__os << __t._M_date << ' ' << __t._M_time;
else
{
- if (__is_neg) [[unlikely]]
- __os << _S_plus_minus[1];
+ if constexpr (chrono::__is_duration_v<_Tp>)
+ if (__is_neg) [[unlikely]]
+ __os << _S_plus_minus[1];
__os << __t;
}
diff --git a/libstdc++-v3/testsuite/std/time/hh_mm_ss/io.cc
b/libstdc++-v3/testsuite/std/time/hh_mm_ss/io.cc
index 072234328c7..ddb1ad77d1e 100644
--- a/libstdc++-v3/testsuite/std/time/hh_mm_ss/io.cc
+++ b/libstdc++-v3/testsuite/std/time/hh_mm_ss/io.cc
@@ -47,9 +47,13 @@ test_format()
auto s = std::format("{}", hh_mm_ss{1h + 23min + 45s});
VERIFY( s == "01:23:45" );
+ s = std::format("{}", hh_mm_ss{-42min});
+ VERIFY( s == "-00:42:00" );
auto ws = std::format(L"{}", hh_mm_ss{1h + 23min + 45s});
VERIFY( ws == L"01:23:45" );
+ ws = std::format(L"{}", hh_mm_ss{-42min});
+ VERIFY( ws == L"-00:42:00" );
// Locale-specific formats:
auto loc = std::locale::classic();
--
2.41.0
