On Wed, Mar 12, 2025 at 1:00 PM Jonathan Wakely <jwak...@redhat.com> wrote:
> On Tue, 11 Mar 2025 at 12:22, Tomasz Kamiński wrote: > > > > Floating points types _Float16, _Float32, _Float64, and bfloat16, > > can be formatted only if std::to_chars overloads for such types > > where provided. Currently this is only the case for architectures > > Spelling: "were provided" > > With that fixed, OK for trunk, thanks for noticing this. > > I think we also want this on the gcc-14 and gcc-13 branches, but after > it's sat on trunk for a while. > OK to backport to both now? > > > where float and double are 32-bits and 64-bits IEEE floating points > types. > > > > This patch updates the preprocessing checks for formatters > > for above types to check _GLIBCXX_FLOAT_IS_IEEE_BINARY32 > > and _GLIBCXX_DOUBLE_IS_IEEE_BINARY64. Making them non-formattable > > on non-IEEE architectures. > > > > 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 (formatter<_Float16, _CharT>): Define only > if > > _GLIBCXX_FLOAT_IS_IEEE_BINARY32 macro is defined. > > (formatter<_Float16, _CharT>): As above. > > (formatter<__gnu_cxx::__bfloat16_t, _CharT>): As above. > > (formatter<_Float64, _CharT>): Define only if > > _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 is defined. > > (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. > > --- > > Tested on x86_64-linux. OK for trunk? > > > > libstdc++-v3/include/std/format | 32 ++++++++------------------------ > > 1 file changed, 8 insertions(+), 24 deletions(-) > > > > diff --git a/libstdc++-v3/include/std/format > b/libstdc++-v3/include/std/format > > index e7e0d2d142b..1809f040077 100644 > > --- a/libstdc++-v3/include/std/format > > +++ b/libstdc++-v3/include/std/format > > @@ -2276,7 +2276,7 @@ namespace __format > > }; > > #endif > > > > -#ifdef __STDCPP_FLOAT16_T__ > > +#if defined(__STDCPP_FLOAT16_T__) && > defined(_GLIBCXX_FLOAT_IS_IEEE_BINARY32) > > // Reuse __formatter_fp<C>::format<float, Out> for _Float16. > > template<__format::__char _CharT> > > struct formatter<_Float16, _CharT> > > @@ -2298,7 +2298,7 @@ namespace __format > > }; > > #endif > > > > -#if defined(__FLT32_DIG__) > > +#if defined(__FLT32_DIG__) && defined(_GLIBCXX_FLOAT_IS_IEEE_BINARY32) > > // Reuse __formatter_fp<C>::format<float, Out> for _Float32. > > template<__format::__char _CharT> > > struct formatter<_Float32, _CharT> > > @@ -2320,7 +2320,7 @@ namespace __format > > }; > > #endif > > > > -#if defined(__FLT64_DIG__) > > +#if defined(__FLT64_DIG__) && defined(_GLIBCXX_DOUBLE_IS_IEEE_BINARY64) > > // Reuse __formatter_fp<C>::format<double, Out> for _Float64. > > template<__format::__char _CharT> > > struct formatter<_Float64, _CharT> > > @@ -2364,7 +2364,7 @@ namespace __format > > }; > > #endif > > > > -#ifdef __STDCPP_BFLOAT16_T__ > > +#if defined(__STDCPP_BFLOAT16_T__) && > defined(_GLIBCXX_FLOAT_IS_IEEE_BINARY32) > > // Reuse __formatter_fp<C>::format<float, Out> for bfloat16_t. > > template<__format::__char _CharT> > > struct formatter<__gnu_cxx::__bfloat16_t, _CharT> > > @@ -3443,22 +3443,16 @@ namespace __format > > return type_identity<float>(); > > #endif > > > > -#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>) > > @@ -3538,16 +3532,6 @@ 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; > > -- > > 2.48.1 > > > >
