On Thu, 17 Apr 2025 at 14:16, Tomasz Kamiński <tkami...@redhat.com> wrote: > > Floating points types _Float16, _Float32, _Float64, and bfloat16, > can be formatted only if std::to_chars overloads for such types > were provided. Currently this is only the case for architectures > where float and double are 32-bits and 64-bits IEEE floating points types. > > Remove a potential UB, where we could produce basic_format_arg > with _M_type set to _Arg_fp32 or _Arg_fp64, that was later not > handled by `_M_visit`. > > libstdc++-v3/ChangeLog: > > * include/std/format (basic_format_arg::_S_to_arg_type): Normalize > _Float32 and _Float64 only to float and double respectivelly. > (basic_format_arg::_S_to_enum): Remove handling of _Float32 and > _Float64. > > Signed-off-by: Tomasz Kamiński <tkami...@redhat.com> > > --- > GCC 13 didn't define formatters for _FloatXX_t types, as they were added > in r14-3305-g6cf214b4fc97f5 that allowed extended floating point types > to be formated before C++23. I think the remaining part of patch is > still revelant for C++23. > Do we still want to backport? OK for 13?
OK for 13. > > > > libstdc++-v3/include/std/format | 24 ++++-------------------- > 1 file changed, 4 insertions(+), 20 deletions(-) > > diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format > index f46012a2b01..c7e43330e7e 100644 > --- a/libstdc++-v3/include/std/format > +++ b/libstdc++-v3/include/std/format > @@ -2979,22 +2979,16 @@ namespace __format > > // TODO bfloat16 and float16 > > -#ifdef __FLT32_DIG__ > +#if defined(__FLT32_DIG__) && defined(_GLIBCXX_FLOAT_IS_IEEE_BINARY32) > else if constexpr (is_same_v<_Td, _Float32>) > -# ifdef _GLIBCXX_FLOAT_IS_IEEE_BINARY32 > return type_identity<float>(); > -# else > - return type_identity<_Float32>(); > -# endif > #endif > -#ifdef __FLT64_DIG__ > + > +#if defined(__FLT64_DIG__) && defined(_GLIBCXX_DOUBLE_IS_IEEE_BINARY64) > else if constexpr (is_same_v<_Td, _Float64>) > -# ifdef _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 > return type_identity<double>(); > -# else > - return type_identity<_Float64>(); > -# endif > #endif > + > #if _GLIBCXX_FORMAT_F128 > # if __FLT128_DIG__ > else if constexpr (is_same_v<_Td, _Float128>) > @@ -3074,16 +3068,6 @@ namespace __format > return _Arg_u128; > #endif > > - // N.B. some of these types will never actually be used here, > - // because they get normalized to a standard floating-point type. > -#if defined __FLT32_DIG__ && ! _GLIBCXX_FLOAT_IS_IEEE_BINARY32 > - else if constexpr (is_same_v<_Tp, _Float32>) > - return _Arg_f32; > -#endif > -#if defined __FLT64_DIG__ && ! _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 > - else if constexpr (is_same_v<_Tp, _Float64>) > - return _Arg_f64; > -#endif > #if _GLIBCXX_FORMAT_F128 == 2 > else if constexpr (is_same_v<_Tp, __format::__float128_t>) > return _Arg_f128; > -- > 2.49.0 >
