On Fri, Jun 27, 2025 at 1:03 PM Tomasz Kamiński <tkami...@redhat.com> wrote:
> The r16-1709-g4b3cefed1a08344495fedec4982d85168bd8173f caused `-Woverflow`
> in empty_spec.cc file. This warning is not cause by any issue in shipping
> code, and results in taking to much shorcut when implementing a test-only
> custom representation type Rep, where long was always used to store a
> value.
> In particular common type for Rep and long long int, was de-facto long.
> This is addressed by adding Under template parameter, that controls the
> type
> of stored value, and handling it properly in common_type specializations.
> No changs to shipping code are necessary.
>
> Secondly, extacting _M_locale_fmt calls in r16-1712-gcaac94, resulted
> in __ctx format parameter no longer being used. This patch removes
> such parameter entirely, and replace _FormatContext template parameter,
> with _OutIter parameter for __out. For consistency type of the __out
> is decoupled from _FormatContext, for functions that still need context:
> * to extract locale (_M_A_a, _M_B_b, _M_c, _M_p, _M_r, _M_subsecs)
> * perform formatting for duration/subseconds (_M_Q, _M_T, _M_f)
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/chrono_io.h (__formatter_chrono::_M_format_to):
> Rename _Out to _OutIter for consistency, and update calls
> to specifier functions.
> (__formatter_chrono::_M_wi, __formatter_chrono::_M_C_y_Y)
> (__formatter_chrono::_M_D_x, __formatter_chrono::_M_d_e)
> (__formatter_chrono::_M_F, __formatter_chrono::_M_g_G)
> (__formatter_chrono::_M_H_I, __formatter_chrono::_M_j)
> (__formatter_chrono::_M_m, __formatter_chrono::_M_M)
> (__formatter_chrono::_M_q, __formatter_chrono::_M_R_X)
> (__formatter_chrono::_M_u_w, __formatter_chrono::_M_U_V_W)
> (__formatter_chrono::_M_z, __formatter_chrono::_M_z):
> Remove _FormatContext parameter, and introduce _OutIter
> for __out type.
> (__formatter_chrono::_M_a_A, __formatter_chrono::_M_B_b)
> (__formatter_chrono::_M_p, __formatter_chrono::_M_Q)
> (__formatter_chrono::_M_r, __formatter_chrono::_M_S)
> (__formatter_chrono::_M_subsecs, __formatter_chrono::_M_T):
> Introduce separate _OutIter template parameter for __out.
> (__formatter_chrono::_M_c, __formatter_chrono::_M_T):
> Likewise, and adjust calls to specifiers functions.
> * testsuite/std/time/format/empty_spec.cc:
>
This now says:
* testsuite/std/time/format/empty_spec.cc: Make underlying
type for Rep configurable.
> ---
> Still testing, but the warning in empty_spec.cc file disapeared when
> using -m32.
>
> libstdc++-v3/include/bits/chrono_io.h | 219 ++++++++----------
> .../testsuite/std/time/format/empty_spec.cc | 43 ++--
> 2 files changed, 128 insertions(+), 134 deletions(-)
>
> diff --git a/libstdc++-v3/include/bits/chrono_io.h
> b/libstdc++-v3/include/bits/chrono_io.h
> index bcfd51b9866..03f58c8a264 100644
> --- a/libstdc++-v3/include/bits/chrono_io.h
> +++ b/libstdc++-v3/include/bits/chrono_io.h
> @@ -942,9 +942,9 @@ namespace __format
> return __out;
> }
>
> - template<typename _Out, typename _FormatContext>
> - _Out
> - _M_format_to(const _ChronoData<_CharT>& __t, _Out __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_format_to(const _ChronoData<_CharT>& __t, _OutIter __out,
> _FormatContext& __fc) const
> {
> auto __first = _M_spec._M_chrono_specs.begin();
> @@ -1005,7 +1005,7 @@ namespace __format
> {
> // %\0 is extension for handling weekday index
> case '\0':
> - __out = _M_wi(__t._M_weekday_index, std::move(__out),
> __fc);
> + __out = _M_wi(__t._M_weekday_index, std::move(__out));
> break;
> case 'a':
> case 'A':
> @@ -1022,41 +1022,41 @@ namespace __format
> case 'C':
> case 'y':
> case 'Y':
> - __out = _M_C_y_Y(__t._M_year, std::move(__out), __fc,
> __c);
> + __out = _M_C_y_Y(__t._M_year, std::move(__out), __c);
> break;
> case 'd':
> case 'e':
> - __out = _M_d_e(__t._M_day, std::move(__out), __fc, __c);
> + __out = _M_d_e(__t._M_day, std::move(__out), __c);
> break;
> case 'D':
> case 'x':
> - __out = _M_D_x(__t, std::move(__out), __fc);
> + __out = _M_D_x(__t, std::move(__out));
> break;
> case 'F':
> - __out = _M_F(__t, std::move(__out), __fc);
> + __out = _M_F(__t, std::move(__out));
> break;
> case 'g':
> case 'G':
> - __out = _M_g_G(__t, std::move(__out), __fc, __c == 'G');
> + __out = _M_g_G(__t, std::move(__out), __c == 'G');
> break;
> case 'H':
> case 'I':
> - __out = _M_H_I(__t._M_hours, __print_sign(), __fc, __c);
> + __out = _M_H_I(__t._M_hours, __print_sign(), __c);
> break;
> case 'j':
> - __out = _M_j(__t, __print_sign(), __fc);
> + __out = _M_j(__t, __print_sign());
> break;
> case 'm':
> - __out = _M_m(__t._M_month, std::move(__out), __fc);
> + __out = _M_m(__t._M_month, std::move(__out));
> break;
> case 'M':
> - __out = _M_M(__t._M_minutes, __print_sign(), __fc);
> + __out = _M_M(__t._M_minutes, __print_sign());
> break;
> case 'p':
> __out = _M_p(__t._M_hours, std::move(__out), __fc);
> break;
> case 'q':
> - __out = _M_q(__t._M_unit_suffix, std::move(__out), __fc);
> + __out = _M_q(__t._M_unit_suffix, std::move(__out));
> break;
> case 'Q':
> __out = _M_Q(__t, __print_sign(), __fc);
> @@ -1066,7 +1066,7 @@ namespace __format
> break;
> case 'R':
> case 'X':
> - __out = _M_R_X(__t, __print_sign(), __fc, __c != 'R');
> + __out = _M_R_X(__t, __print_sign(), __c != 'R');
> break;
> case 'T':
> __out = _M_T(__t, __print_sign(), __fc);
> @@ -1076,18 +1076,18 @@ namespace __format
> break;
> case 'u':
> case 'w':
> - __out = _M_u_w(__t._M_weekday, std::move(__out), __fc,
> __c);
> + __out = _M_u_w(__t._M_weekday, std::move(__out), __c);
> break;
> case 'U':
> case 'V':
> case 'W':
> - __out = _M_U_V_W(__t, std::move(__out), __fc, __c);
> + __out = _M_U_V_W(__t, std::move(__out), __c);
> break;
> case 'z':
> - __out = _M_z(__t._M_zone_offset, std::move(__out), __fc,
> (bool)__mod);
> + __out = _M_z(__t._M_zone_offset, std::move(__out),
> (bool)__mod);
> break;
> case 'Z':
> - __out = _M_Z(__t._M_zone_abbrev, std::move(__out), __fc);
> + __out = _M_Z(__t._M_zone_abbrev, std::move(__out));
> break;
> case 'n':
> *__out++ = __literals[0];
> @@ -1128,10 +1128,9 @@ namespace __format
> return std::move(__out);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_wi(unsigned __wi, typename _FormatContext::iterator __out,
> - _FormatContext& __ctx) const
> + template<typename _OutIter>
> + _OutIter
> + _M_wi(unsigned __wi, _OutIter __out) const
> {
> // %\0 Extension to format weekday index, used only by empty
> format spec
> _CharT __buf[3];
> @@ -1142,9 +1141,9 @@ namespace __format
> return std::move(__out);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_a_A(chrono::weekday __wd, typename _FormatContext::iterator
> __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_a_A(chrono::weekday __wd, _OutIter __out,
> _FormatContext& __ctx, bool __full) const
> {
> // %a Locale's abbreviated weekday name.
> @@ -1172,9 +1171,9 @@ namespace __format
> return _M_write(std::move(__out), __loc, __str);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_b_B(chrono::month __m, typename _FormatContext::iterator __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_b_B(chrono::month __m, _OutIter __out,
> _FormatContext& __ctx, bool __full) const
> {
> // %b Locale's abbreviated month name.
> @@ -1202,9 +1201,9 @@ namespace __format
> return _M_write(std::move(__out), __loc, __str);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_c(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_c(const _ChronoData<_CharT>& __t, _OutIter __out,
> _FormatContext& __ctx) const
> {
> // %c Locale's date and time representation, for C-locale: %a
> %b %e %T %Y
> @@ -1214,17 +1213,16 @@ namespace __format
> *__out = _S_space;
> __out = _M_b_B(__t._M_month, std::move(++__out), __ctx, false);
> *__out = _S_space;
> - __out = _M_d_e(__t._M_day, std::move(++__out), __ctx, 'e');
> + __out = _M_d_e(__t._M_day, std::move(++__out), 'e');
> *__out = _S_space;
> - __out = _M_R_X(__t, std::move(++__out), __ctx, true);
> + __out = _M_R_X(__t, std::move(++__out), true);
> *__out = _S_space;
> - return _M_C_y_Y(__t._M_year, std::move(++__out), __ctx, 'Y');
> + return _M_C_y_Y(__t._M_year, std::move(++__out), 'Y');
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_C_y_Y(chrono::year __y, typename _FormatContext::iterator __out,
> - _FormatContext& __ctx, _CharT __conv) const
> + template<typename _OutIter>
> + _OutIter
> + _M_C_y_Y(chrono::year __y, _OutIter __out, _CharT __conv) const
> {
> // %C Year divided by 100 using floored division.
> // %EC Locale's alternative preresentation of the century (era
> name).
> @@ -1273,10 +1271,9 @@ namespace __format
> return __out;
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_D_x(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> - _FormatContext&) const
> + template<typename _OutIter>
> + _OutIter
> + _M_D_x(const _ChronoData<_CharT>& __t, _OutIter __out) const
> {
> // %D Equivalent to %m/%d/%y
> // %x Locale's date rep, for C-locale: %m/%d/%y
> @@ -1308,10 +1305,9 @@ namespace __format
> return std::move(__out);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_d_e(chrono::day __d, typename _FormatContext::iterator __out,
> - _FormatContext& __ctx, _CharT __conv) const
> + template<typename _OutIter>
> + _OutIter
> + _M_d_e(chrono::day __d, _OutIter __out, _CharT __conv) const
> {
> // %d The day of month as a decimal number.
> // %Od Locale's alternative representation.
> @@ -1336,10 +1332,9 @@ namespace __format
> return std::move(__out);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_F(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> - _FormatContext&) const
> + template<typename _OutIter>
> + _OutIter
> + _M_F(const _ChronoData<_CharT>& __t, _OutIter __out) const
> {
> auto __di = (unsigned)__t._M_day;
> auto __mi = (unsigned)__t._M_month;
> @@ -1376,10 +1371,10 @@ namespace __format
> return std::move(__out);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_g_G(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> - _FormatContext& __ctx, bool __full) const
> + template<typename _OutIter>
> + _OutIter
> + _M_g_G(const _ChronoData<_CharT>& __t, _OutIter __out,
> + bool __full) const
> {
> // %g last two decimal digits of the ISO week-based year.
> // %G ISO week-based year.
> @@ -1389,13 +1384,12 @@ namespace __format
> __d -= (__t._M_weekday - Monday) - days(3);
> // ISO week-based year is the year that contains that Thursday:
> year __y = year_month_day(__d).year();
> - return _M_C_y_Y(__y, std::move(__out), __ctx, "yY"[__full]);
> + return _M_C_y_Y(__y, std::move(__out), "yY"[__full]);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_H_I(chrono::hours __h, typename _FormatContext::iterator __out,
> - _FormatContext& __ctx, _CharT __conv) const
> + template<typename _OutIter>
> + _OutIter
> + _M_H_I(chrono::hours __h, _OutIter __out, _CharT __conv) const
> {
> // %H The hour (24-hour clock) as a decimal number.
> // %OH Locale's alternative representation.
> @@ -1416,10 +1410,9 @@ namespace __format
> return __format::__write(std::move(__out), _S_two_digits(__i));
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_j(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> - _FormatContext&) const
> + template<typename _OutIter>
> + _OutIter
> + _M_j(const _ChronoData<_CharT>& __t, _OutIter __out) const
> {
> if (_M_spec._M_time_only)
> {
> @@ -1432,10 +1425,9 @@ namespace __format
> __t._M_day_of_year.count());
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_m(chrono::month __m, typename _FormatContext::iterator __out,
> - _FormatContext& __ctx) const
> + template<typename _OutIter>
> + _OutIter
> + _M_m(chrono::month __m, _OutIter __out) const
> {
> // %m month as a decimal number.
> // %Om Locale's alternative representation.
> @@ -1446,10 +1438,9 @@ namespace __format
> return __format::__write(std::move(__out), _S_str_d2(__buf,
> __i));
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_M(chrono::minutes __m, typename _FormatContext::iterator __out,
> - _FormatContext& __ctx) const
> + template<typename _OutIter>
> + _OutIter
> + _M_M(chrono::minutes __m, _OutIter __out) const
> {
> // %M The minute as a decimal number.
> // %OM Locale's alternative representation.
> @@ -1458,9 +1449,9 @@ namespace __format
> return __format::__write(std::move(__out), _S_two_digits(__i));
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_p(chrono::hours __h, typename _FormatContext::iterator __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_p(chrono::hours __h, _OutIter __out,
> _FormatContext& __ctx) const
> {
> // %p The locale's equivalent of the AM/PM designations.
> @@ -1475,27 +1466,26 @@ namespace __format
> return _M_write(std::move(__out), __loc, __ampm[__hi >= 12]);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_q(__string_view __us, typename _FormatContext::iterator __out,
> - _FormatContext&) const
> + template<typename _OutIter>
> + _OutIter
> + _M_q(__string_view __us, _OutIter __out) const
> {
> // %q The duration's unit suffix
> return __format::__write(std::move(__out), __us);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_Q(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> - _FormatContext& __ctx) const
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_Q(const _ChronoData<_CharT>& __t, _OutIter __out,
> + _FormatContext&) const
> {
> // %Q The duration's numeric value.
> return std::vformat_to(std::move(__out), _S_empty_spec,
> __t._M_ereps);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_r(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_r(const _ChronoData<_CharT>& __t, _OutIter __out,
> _FormatContext& __ctx) const
> {
> // %r Locale's 12-hour clock time, for C-locale: %I:%M:%S %p
> @@ -1516,10 +1506,10 @@ namespace __format
> return _M_p(__t._M_hours, std::move(__out), __ctx);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_R_X(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> - _FormatContext& __ctx, bool __secs) const
> + template<typename _OutIter>
> + _OutIter
> + _M_R_X(const _ChronoData<_CharT>& __t, _OutIter __out,
> + bool __secs) const
> {
> // %R Equivalent to %H:%M
> // %X Locale's time rep, for C-locale: %H:%M:%S (without
> subseconds)
> @@ -1549,9 +1539,9 @@ namespace __format
> return __format::__write(std::move(__out), __sv);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_S(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_S(const _ChronoData<_CharT>& __t, _OutIter __out,
> _FormatContext& __ctx, bool __subs = true) const
> {
> // %S Seconds as a decimal number.
> @@ -1565,10 +1555,9 @@ namespace __format
> return __out;
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_subsecs(const _ChronoData<_CharT>& __t,
> - typename _FormatContext::iterator __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_subsecs(const _ChronoData<_CharT>& __t, _OutIter __out,
> _FormatContext& __ctx) const
> {
> unsigned __prec = _M_spec._M_prec_kind != _WP_none
> @@ -1628,20 +1617,19 @@ namespace __format
>
> // %t handled in _M_format
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_T(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> + template<typename _OutIter, typename _FormatContext>
> + _OutIter
> + _M_T(const _ChronoData<_CharT>& __t, _OutIter __out,
> _FormatContext& __ctx) const
> {
> // %T Equivalent to %H:%M:%S, with subseconds
> - __out = _M_R_X(__t, std::move(__out), __ctx, true);
> + __out = _M_R_X(__t, std::move(__out), true);
> return _M_subsecs(__t, std::move(__out), __ctx);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_u_w(chrono::weekday __wd, typename _FormatContext::iterator
> __out,
> - _FormatContext& __ctx, _CharT __conv) const
> + template<typename _OutIter>
> + _OutIter
> + _M_u_w(chrono::weekday __wd, _OutIter __out, _CharT __conv) const
> {
> // %u ISO weekday as a decimal number (1-7), where Monday is 1.
> // %Ou Locale's alternative numeric rep.
> @@ -1653,10 +1641,9 @@ namespace __format
> return __format::__write(std::move(__out), _S_str_d1(__buf,
> __wdi));
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_U_V_W(const _ChronoData<_CharT>& __t, typename
> _FormatContext::iterator __out,
> - _FormatContext& __ctx, _CharT __conv) const
> + template<typename _OutIter>
> + _OutIter
> + _M_U_V_W(const _ChronoData<_CharT>& __t, _OutIter __out, _CharT
> __conv) const
> {
> // %U Week number of the year as a decimal number, from first
> Sunday.
> // %OU Locale's alternative numeric rep.
> @@ -1686,10 +1673,9 @@ namespace __format
> return __format::__write(std::move(__out), __sv);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_z(chrono::seconds __ts, typename _FormatContext::iterator __out,
> - _FormatContext&, bool __mod = false) const
> + template<typename _OutIter>
> + _OutIter
> + _M_z(chrono::seconds __ts, _OutIter __out, bool __mod = false)
> const
> {
> if (__ts == 0s)
> {
> @@ -1711,10 +1697,9 @@ namespace __format
> return __format::__write(std::move(__out), __sv);
> }
>
> - template<typename _FormatContext>
> - typename _FormatContext::iterator
> - _M_Z(__string_view __abbrev, typename _FormatContext::iterator
> __out,
> - _FormatContext& __ctx) const
> + template<typename _OutIter>
> + _OutIter
> + _M_Z(__string_view __abbrev, _OutIter __out) const
> { return __format::__write(std::move(__out), __abbrev); }
>
> // %% handled in _M_format
> diff --git a/libstdc++-v3/testsuite/std/time/format/empty_spec.cc
> b/libstdc++-v3/testsuite/std/time/format/empty_spec.cc
> index 923df3d813c..ef1b19d688c 100644
> --- a/libstdc++-v3/testsuite/std/time/format/empty_spec.cc
> +++ b/libstdc++-v3/testsuite/std/time/format/empty_spec.cc
> @@ -77,15 +77,18 @@ test_padding()
> VERIFY( res == WIDEN("==16 is not a valid month==") );
> }
>
> -template<typename Ret = void>
> +template<typename Ret = void, typename Under = long>
> struct Rep
> {
> using Return
> = std::conditional_t<std::is_void_v<Ret>, Rep, Ret>;
>
> - Rep(long v = 0) : val(v) {}
> + Rep(Under v = 0) : val(v) {}
>
> - operator long() const
> + template<typename ORet, typename OUnder>
> + Rep(Rep<ORet, OUnder> o) : val(o.val) {}
> +
> + operator Under() const
> { return val; }
>
> Return
> @@ -119,37 +122,43 @@ struct Rep
> operator<<(std::basic_ostream<CharT>& os, const Rep& t)
> { return os << t.val << WIDEN("[via <<]"); }
>
> - long val;
> + Under val;
> +};
> +
> +template<typename Ret, typename Under1, typename Under2>
> +struct std::common_type<Rep<Ret, Under1>, Rep<Ret, Under2>>
> +{
> + using type = Rep<Ret, std::common_type_t<Under1, Under2>>;
> };
>
> -template<typename Ret, typename Other>
> +template<typename Ret, typename Under, typename Other>
> requires std::is_integral_v<Other>
> -struct std::common_type<Rep<Ret>, Other>
> +struct std::common_type<Rep<Ret, Under>, Other>
> {
> - using type = Rep<Ret>;
> + using type = Rep<Ret, std::common_type_t<Under, Other>>;
> };
>
> -template<typename Ret, typename Other>
> +template<typename Ret, typename Under, typename Other>
> requires std::is_integral_v<Other>
> -struct std::common_type<Other, Rep<Ret>>
> - : std::common_type<Rep<Ret>, Other>
> +struct std::common_type<Other, Rep<Ret, Under>>
> + : std::common_type<Rep<Ret, Under>, Other>
> { };
>
> -template<typename Ret>
> -struct std::numeric_limits<Rep<Ret>>
> - : std::numeric_limits<long>
> +template<typename Ret, typename Under>
> +struct std::numeric_limits<Rep<Ret, Under>>
> + : std::numeric_limits<Under>
> { };
>
> -template<typename Ret, typename CharT>
> -struct std::formatter<Rep<Ret>, CharT>
> - : std::formatter<long, CharT>
> +template<typename Ret, typename Under, typename CharT>
> +struct std::formatter<Rep<Ret, Under>, CharT>
> + : std::formatter<Under, CharT>
> {
> template<typename Out>
> typename std::basic_format_context<Out, CharT>::iterator
> format(const Rep<Ret>& t, std::basic_format_context<Out, CharT>& ctx)
> const
> {
> constexpr std::basic_string_view<CharT> suffix = WIDEN("[via
> format]");
> - auto out = std::formatter<long, CharT>::format(t.val, ctx);
> + auto out = std::formatter<Under, CharT>::format(t.val, ctx);
> return std::ranges::copy(suffix, out).out;
> }
> };
> --
> 2.49.0
>
>
