[PATCH v3] libstdc++: Fixed localized empty-spec formatting for months/weekdays [PR121154]
Jonathan Wakely
jwakely@redhat.com
Fri Jul 18 13:04:16 GMT 2025
On 18/07/25 14:01 +0200, Tomasz Kamiński wrote:
>Previously for localized output, if _M_debug option was send, the _M_check_ok
>completed succesfully and _M_locale_fmt was called for months/weekdays that
>are !ok().
>
>This patch lifts debug checks from each conversion function into _M_check_ok,
>that in case of !ok() values return a string_view containing the kind of
>calendar data, to be included after "is not a valid" string. The localized
>output (_M_locale_fmt) is not used if string is non-empty.
>The emitting of this message is now handled in _M_format_to, further reducing
>each specifier function.
>
>To handle weekday (%a,%A) and month (%b,%B), _M_check_ok now accepts a
>mutable reference to conversion specifier, and updates it to corresponding
>numeric value (%w, %m). Extra care needs to be taken to handle a month(0)
>that needs to be printed as single digit in debug format.
>
>Finally, the _M_time_point is replaced with _M_needs_ok_check member, that
>indicates if input contains any user-suplied values that are checked for
>being ok() and these values are referenced in chrono-specs.
>
> PR libstdc++/PR121154
>
>libstdc++-v3/ChangeLog:
>
> * include/bits/chrono_io.h _ChronoSpec::_M_time_point: Remove.
> (_ChronoSpec::_M_needs_ok_check): Define
> (__formatter_chrono::_M_parse): Set _M_needs_ok_check.
> (__formatter_chrono::_M_check_ok): Check values also for debug mode,
> and return __string_view.
> (__formatter_chrono::_M_format_to): Handle results of _M_check_ok.
> (__formatter_chrono::_M_wi, __formatter_chrono::_M_a_A)
> (__formatter_chrono::_M_b_B, __formatter_chrono::_M_C_y_Y)
> (__formatter_chrono::_M_d_e, __formatter_chrono::_M_F):
> Removed handling of _M_debug.
> (__formatter_chrono::__M_m): Print zero unpadded in _M_debug mode.
> (__formatter_duration::_S_spec_for): Remove _M_time_point refernce.
> (__formatter_duration::_M_parse): Override _M_needs_ok_check.
> * testsuite/std/time/month/io.cc: Test for localized !ok() values.
> * testsuite/std/time/weekday/io.cc: Test for localized !ok() values.
>---
>v3 just fixes some typos in comments and commit message.
>
> libstdc++-v3/include/bits/chrono_io.h | 139 +++++++++++-------
> libstdc++-v3/testsuite/std/time/month/io.cc | 7 +
> libstdc++-v3/testsuite/std/time/weekday/io.cc | 2 +
> 3 files changed, 96 insertions(+), 52 deletions(-)
>
>diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h
>index fe3c9126749..95e0d489cf4 100644
>--- a/libstdc++-v3/include/bits/chrono_io.h
>+++ b/libstdc++-v3/include/bits/chrono_io.h
>@@ -280,8 +280,9 @@ namespace __format
> // in the format-spec, e.g. "{:L%a}" is localized and locale-specific,
> // but "{:L}" is only localized and "{:%a}" is only locale-specific.
> unsigned _M_locale_specific : 1;
>- // Indicates that we are handling time_point.
>- unsigned _M_time_point : 1;
>+ // Indicates if parts that are checked for ok are comming directly from input,
"are comming directly from input" -> "come directly from the input"
or "the source" instead of "the input" ? that's what a comment below
says.
OK for trunk with that changed - thanks.
>+ // instead of being computed.
>+ unsigned _M_needs_ok_check : 1;
> // Indicates that duration should be treated as floating point.
> unsigned _M_floating_point_rep : 1;
> // Indicate that duration uses user-defined representation.
>@@ -570,7 +571,15 @@ namespace __format
>
> _ChronoSpec<_CharT> __spec = __def;
>
>- auto __finalize = [this, &__spec] {
>+ auto __finalize = [this, &__spec, &__def] {
>+ using enum _ChronoParts;
>+ _ChronoParts __checked
>+ = __spec._M_debug ? _YearMonthDay|_IndexedWeekday
>+ : _Month|_Weekday;
>+ // n.b. for calendar types __def._M_needed contains only parts
>+ // copied from source, remaining ones are computed, and thus ok
>+ __spec._M_needs_ok_check
>+ = __spec._M_needs(__def._M_needed & __checked);
> _M_spec = __spec;
> };
>
>@@ -821,10 +830,10 @@ namespace __format
> __throw_format_error("chrono format error: unescaped '%' in "
> "chrono-specs");
>
>- _M_spec = __spec;
>- _M_spec._M_chrono_specs
>- = __string_view(__chrono_specs, __first - __chrono_specs);
>+ __spec._M_chrono_specs
>+ = __string_view(__chrono_specs, __first - __chrono_specs);
>
>+ __finalize();
> return __first;
> }
>
>@@ -972,30 +981,71 @@ namespace __format
> return __out;
> }
>
>- void
>- _M_check_ok(const _ChronoData<_CharT>& __t, _CharT __conv) const
>+ __string_view
>+ _M_check_ok(const _ChronoData<_CharT>& __t, _CharT& __conv) const
> {
>- // n.b. for time point all date parts are computed, so
>- // they are always ok.
>- if (_M_spec._M_time_point || _M_spec._M_debug)
>- return;
>+ if (!_M_spec._M_debug)
>+ {
>+ switch (__conv)
>+ {
>+ case 'a':
>+ case 'A':
>+ if (!__t._M_weekday.ok()) [[unlikely]]
>+ __throw_format_error("format error: invalid weekday");
>+ break;
>+ case 'b':
>+ case 'h':
>+ case 'B':
>+ if (!__t._M_month.ok()) [[unlikely]]
>+ __throw_format_error("format error: invalid month");
>+ break;
>+ default:
>+ break;
>+ }
>+ return __string_view();
>+ }
>
> switch (__conv)
> {
>+ // %\0 is extension for handling weekday index
>+ case '\0':
>+ if (__t._M_weekday_index < 1 || __t._M_weekday_index > 5) [[unlikely]]
>+ return _GLIBCXX_WIDEN("index");
>+ break;
> case 'a':
> case 'A':
> if (!__t._M_weekday.ok()) [[unlikely]]
>- __throw_format_error("format error: invalid weekday");
>- return;
>+ {
>+ __conv = 'w'; // print as decimal number
>+ return _GLIBCXX_WIDEN("weekday");
>+ }
>+ break;
> case 'b':
> case 'h':
> case 'B':
> if (!__t._M_month.ok()) [[unlikely]]
>- __throw_format_error("format error: invalid month");
>- return;
>+ {
>+ __conv = 'm'; // print as decimal number
>+ return _GLIBCXX_WIDEN("month");
>+ }
>+ break;
>+ case 'd':
>+ case 'e':
>+ if (!__t._M_day.ok()) [[unlikely]]
>+ return _GLIBCXX_WIDEN("day");
>+ break;
>+ case 'F':
>+ if (!(__t._M_year/__t._M_month/__t._M_day).ok()) [[unlikely]]
>+ return _GLIBCXX_WIDEN("date");
>+ break;
>+ case 'Y':
>+ if (!__t._M_year.ok()) [[unlikely]]
>+ return _GLIBCXX_WIDEN("year");
>+ break;
> default:
>- return;
>+ break;
> }
>+ return __string_view();
> }
>
> template<typename _OutIter, typename _FormatContext>
>@@ -1054,9 +1104,12 @@ namespace __format
> do
> {
> _CharT __c = *__first++;
>- _M_check_ok(__t, __c);
>+ __string_view __invalid;
>+ if (_M_spec._M_needs_ok_check)
>+ __invalid = _M_check_ok(__t, __c);
>
>- if (__use_locale_fmt && _S_localized_spec(__c, __mod)) [[unlikely]]
>+ if (__invalid.empty() &&__use_locale_fmt
>+ && _S_localized_spec(__c, __mod)) [[unlikely]]
> __out = _M_locale_fmt(std::move(__out), __fc.locale(),
> __tm, __c, __mod);
> else switch (__c)
>@@ -1164,6 +1217,14 @@ namespace __format
> __first = __last;
> break;
> }
>+
>+ if (!__invalid.empty())
>+ {
>+ constexpr __string_view __pref = _GLIBCXX_WIDEN(" is not a valid ");
>+ __out = __format::__write(std::move(__out), __pref);
>+ __out = __format::__write(std::move(__out), __invalid);
>+ }
>+
> __mod = _CharT();
> // Scan for next '%' and write out everything before it.
> __string_view __str(__first, __last - __first);
>@@ -1193,9 +1254,6 @@ namespace __format
> // %\0 Extension to format weekday index, used only by empty format spec
> _CharT __buf[3];
> __out = __format::__write(std::move(__out), _S_str_d1(__buf, __wi));
>- if (_M_spec._M_debug && (__wi < 1 || __wi > 5))
>- __out = __format::__write(std::move(__out),
>- __string_view(_GLIBCXX_WIDEN(" is not a valid index")));
> return std::move(__out);
> }
>
>@@ -1205,15 +1263,6 @@ namespace __format
> {
> // %a Locale's abbreviated weekday name.
> // %A Locale's full weekday name.
>- if (_M_spec._M_debug && !__wd.ok())
>- {
>- _CharT __buf[3];
>- __out = __format::__write(std::move(__out),
>- _S_str_d1(__buf, __wd.c_encoding()));
>- return __format::__write(std::move(__out),
>- __string_view(_GLIBCXX_WIDEN(" is not a valid weekday")));
>- }
>-
> __string_view __str = _S_weekdays[__wd.c_encoding()];
> if (!__full)
> __str = __str.substr(0, 3);
>@@ -1226,15 +1275,6 @@ namespace __format
> {
> // %b Locale's abbreviated month name.
> // %B Locale's full month name.
>- if (_M_spec._M_debug && !__m.ok())
>- {
>- _CharT __buf[3];
>- __out = __format::__write(std::move(__out),
>- _S_str_d1(__buf, (unsigned)__m));
>- return __format::__write(std::move(__out),
>- __string_view(_GLIBCXX_WIDEN(" is not a valid month")));
>- }
>-
> __string_view __str = _S_months[(unsigned)__m - 1];
> if (!__full)
> __str = __str.substr(0, 3);
>@@ -1303,10 +1343,6 @@ namespace __format
> }
> __out = __format::__write(std::move(__out), __sv);
> }
>-
>- if (_M_spec._M_debug && __conv == 'Y' && !__y.ok()) [[unlikely]]
>- __out = __format::__write(std::move(__out),
>- __string_view(_GLIBCXX_WIDEN(" is not a valid year")));
> return __out;
> }
>
>@@ -1365,9 +1401,6 @@ namespace __format
> }
>
> __out = __format::__write(std::move(__out), __sv);
>- if (_M_spec._M_debug && !__d.ok()) [[unlikely]]
>- __out = __format::__write(std::move(__out),
>- __string_view(_GLIBCXX_WIDEN(" is not a valid day")));
> return std::move(__out);
> }
>
>@@ -1404,9 +1437,6 @@ namespace __format
> __out = __format::__write(std::move(__out), __sv);
> }
>
>- if (_M_spec._M_debug && !(__t._M_year/__t._M_month/__t._M_day).ok())
>- __out = __format::__write(std::move(__out),
>- __string_view(_GLIBCXX_WIDEN(" is not a valid date")));
> return std::move(__out);
> }
>
>@@ -1474,8 +1504,10 @@ namespace __format
> {
> // %m month as a decimal number.
> // %Om Locale's alternative representation.
>-
> auto __i = (unsigned)__m;
>+ if (__i == 0 && _M_spec._M_debug) [[unlikely]]
>+ // 0 should not be padded to two digits
>+ return __format::__write(std::move(__out), _S_digit(0));
>
> _CharT __buf[3];
> return __format::__write(std::move(__out), _S_str_d2(__buf, __i));
>@@ -1852,7 +1884,6 @@ namespace __format
> using enum _ChronoParts;
>
> _ChronoSpec<_CharT> __res{};
>- __res._M_time_point = (__parts & _DateTime) == _DateTime;
> __res._M_floating_point_rep = chrono::treat_as_floating_point_v<_Rep>;
> __res._M_custom_rep = !is_arithmetic_v<_Rep>;
> __res._M_prec = chrono::hh_mm_ss<_Duration>::fractional_width;
>@@ -1901,6 +1932,10 @@ namespace __format
>
> auto __res
> = __formatter_chrono<_CharT>::_M_parse(__pc, __parts, __def);
>+ // n.b. durations do not contain date parts, and for time point all
>+ // date parts are computed, and they are always ok.
>+ _M_spec._M_needs_ok_check = false;
>+
> // check for custom floating point durations, if digits of output
> // will contain subseconds, then formatters must support specifying
> // precision.
>diff --git a/libstdc++-v3/testsuite/std/time/month/io.cc b/libstdc++-v3/testsuite/std/time/month/io.cc
>index 99ec0737305..edfa196b71c 100644
>--- a/libstdc++-v3/testsuite/std/time/month/io.cc
>+++ b/libstdc++-v3/testsuite/std/time/month/io.cc
>@@ -24,6 +24,9 @@ test_ostream()
> ss.imbue(std::locale(ISO_8859(15,fr_FR)));
> ss << month(1);
> VERIFY( ss.str() == "janv." );
>+ ss.str("");
>+ ss << month(0) << '|' << month(13);
>+ VERIFY( ss.str() == "0 is not a valid month|13 is not a valid month" );
> }
>
> void
>@@ -66,6 +69,10 @@ test_format()
> VERIFY( s == "Jan" );
> s = std::format(loc_fr, "{:L%b}", month(1));
> VERIFY( s == "janv." );
>+ s = std::format(loc_fr, "{:L}", month(0));
>+ VERIFY( s == "0 is not a valid month" );
>+ s = std::format(loc_fr, "{:L}", month(13));
>+ VERIFY( s == "13 is not a valid month" );
>
> std::string_view specs = "aAbBcCdDeFgGhHIjmMpqQrRSTuUVwWxXyYzZ";
> std::string_view my_specs = "bBhm";
>diff --git a/libstdc++-v3/testsuite/std/time/weekday/io.cc b/libstdc++-v3/testsuite/std/time/weekday/io.cc
>index a56cdaef88c..90a9bcbbb62 100644
>--- a/libstdc++-v3/testsuite/std/time/weekday/io.cc
>+++ b/libstdc++-v3/testsuite/std/time/weekday/io.cc
>@@ -69,6 +69,8 @@ test_format()
> VERIFY( s == "Mon" );
> s = std::format(loc_fr, "{:L%a}", weekday(1));
> VERIFY( s == "lun." );
>+ s = std::format(loc_fr, "{:L}", weekday(25));
>+ VERIFY( s == "25 is not a valid weekday" );
>
> std::string_view specs = "aAbBcCdDeFgGhHIjmMpqQrRSTuUVwWxXyYzZ";
> std::string_view my_specs = "aAuw";
>--
>2.49.0
>
>
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