On Wed, 2 Jul 2025 at 10:30, Tomasz Kaminski <tkami...@redhat.com> wrote:
>
>
>
> On Wed, Jul 2, 2025 at 9:13 AM XU Kailiang <xu2k...@outlook.com> wrote:
>>
>>
>> C++ formatting locale could have a custom time_put that performs
>> differently from the C locale, so do not use __timepunct directly.
>>
>> libstdc++-v3/ChangeLog:
>>
>> PR libstdc++/117214
>> * include/bits/chrono_io.h (__formatter_chrono::_M_a_A,
>> __formatter_chrono::_M_b_B, __formatter_chrono::_M_p): use
>> _M_locale_fmt to format %a/%A/%b/%B/%p.
>> * testsuite/std/time/format/pr117214_custom_timeput.cc: New
>> test.
>>
>> Signed-off-by: XU Kailiang <xu2k...@outlook.com>
>> ---
>> libstdc++-v3/include/bits/chrono_io.h | 31 ++++++----------
>> .../time/format/pr117214_custom_timeput.cc | 36 +++++++++++++++++++
>> 2 files changed, 47 insertions(+), 20 deletions(-)
>> create mode 100644
>> libstdc++-v3/testsuite/std/time/format/pr117214_custom_timeput.cc
>>
>> diff --git a/libstdc++-v3/include/bits/chrono_io.h
>> b/libstdc++-v3/include/bits/chrono_io.h
>> index abbf4efcc3b..8358105c26b 100644
>> --- a/libstdc++-v3/include/bits/chrono_io.h
>> +++ b/libstdc++-v3/include/bits/chrono_io.h
>> @@ -905,14 +905,10 @@ namespace __format
>> }
>>
>> locale __loc = _M_locale(__ctx);
>> - const auto& __tp = use_facet<__timepunct<_CharT>>(__loc);
>> - const _CharT* __days[7];
>> - if (__full)
>> - __tp._M_days(__days);
>> - else
>> - __tp._M_days_abbreviated(__days);
>> - __string_view __str(__days[__wd.c_encoding()]);
>> - return _M_write(std::move(__out), __loc, __str);
>> + struct tm __tm{};
>> + __tm.tm_wday = __wd.c_encoding();
>> + return _M_locale_fmt(std::move(__out), __loc, __tm,
>> + __full ? 'A' : 'a', 0);
>
> I have recently removed all call to _M_locale_fmt from inside the specifiers,
> into the format loop, instead of calling it per each specifier individually.
> I think, we should follow same approach here, by updating _S_localized_spec to
> return true for all above specifiers.
Yes please.
> Then we can remove calls to _M_write and replace it with __format_writes, as
> this functions will be only used for C locale.
>>
>> }
>>
>> template<typename _Tp, typename _FormatContext>
>> @@ -936,14 +932,10 @@ namespace __format
>> }
>>
>> locale __loc = _M_locale(__ctx);
>> - const auto& __tp = use_facet<__timepunct<_CharT>>(__loc);
>> - const _CharT* __months[12];
>> - if (__full)
>> - __tp._M_months(__months);
>> - else
>> - __tp._M_months_abbreviated(__months);
>> - __string_view __str(__months[(unsigned)__m - 1]);
>> - return _M_write(std::move(__out), __loc, __str);
>> + struct tm __tm{};
>> + __tm.tm_mon = (unsigned)__m - 1;
>> + return _M_locale_fmt(std::move(__out), __loc, __tm,
>> + __full ? 'B' : 'b', 0);
>> }
>>
>> template<typename _Tp, typename _FormatContext>
>> @@ -1329,10 +1321,9 @@ namespace __format
>> __hi %= 24;
>>
>> locale __loc = _M_locale(__ctx);
>> - const auto& __tp = use_facet<__timepunct<_CharT>>(__loc);
>> - const _CharT* __ampm[2];
>> - __tp._M_am_pm(__ampm);
>> - return _M_write(std::move(__out), __loc, __ampm[__hi >= 12]);
>> + struct tm __tm{};
>> + __tm.tm_hour = __hi;
>> + return _M_locale_fmt(std::move(__out), __loc, __tm, 'p', 0);
>> }
>>
>> template<typename _Tp, typename _FormatContext>
>> diff --git
>> a/libstdc++-v3/testsuite/std/time/format/pr117214_custom_timeput.cc
>> b/libstdc++-v3/testsuite/std/time/format/pr117214_custom_timeput.cc
>> new file mode 100644
>> index 00000000000..8c9f3d29bc6
>> --- /dev/null
>> +++ b/libstdc++-v3/testsuite/std/time/format/pr117214_custom_timeput.cc
>> @@ -0,0 +1,36 @@
>> +// { dg-do run { target c++20 } }
>> +
>> +#include <chrono>
>> +#include <format>
>> +#include <locale>
>> +#include <testsuite_hooks.h>
>> +
>> +struct custom_time_put : std::time_put<char>
>> +{
>> + iter_type
>> + do_put(iter_type out, std::ios_base& io, char_type fill, const tm* t,
>> + char format, char modifier) const override
>> + {
>> + using Base = std::time_put<char>;
>> +
>> + switch (format) {
>> + case 'a': case 'A': case 'b': case 'B': case 'p':
>> + *out++ = '[';
>> + *out++ = format;
>> + *out++ = ']';
>> + }
>> + return Base::do_put(out, io, fill, t, format, modifier);
>> + }
>> +};
>> +
>> +int main()
>> +{
>> + using namespace std::chrono;
>> + std::locale loc(std::locale::classic(), new custom_time_put);
>> +#define test(t, fmt, exp) VERIFY( std::format(loc, fmt, t) == exp )
>> + test(Monday, "{:L%a}", "[a]Mon");
>> + test(Monday, "{:L%A}", "[A]Monday");
>> + test(January, "{:L%b}", "[b]Jan");
>> + test(January, "{:L%B}", "[B]January");
>> + test(1h, "{:L%p}", "[p]AM");
>> +}
>> --
>> 2.50.0
>>
