https://gcc.gnu.org/g:2a82d4c859bd0eca4fe31fc79d234abd05e6a9d8
commit r16-2056-g2a82d4c859bd0eca4fe31fc79d234abd05e6a9d8
Author: Tomasz Kamiński <tkami...@redhat.com>
Date: Fri May 16 07:12:36 2025 +0200
libstdc++: Format __float128 as _Float128 only when long double is not 128
IEEE [PR120976]
For powerpc64 and sparc architectures that both have __float128 and 128bit
long double,
the __float128 is same type as long double/__ieee128 and already
formattable.
The remaining specialization makes __float128 formattable on x86_64 via
_Float128,
however __float128 is now not formattable on x86_32 (-m32) with
-mlong-double-128,
where __float128 is distinct type from long double that is 128bit IEEE.
PR libstdc++/120976
libstdc++-v3/ChangeLog:
* include/std/format (formatter<__float128, _Char_T): Define if
_GLIBCXX_FORMAT_F128 == 2.
Reviewed-by: Jonathan Wakely <jwak...@redhat.com>
Signed-off-by: Tomasz Kamiński <tkami...@redhat.com>
Diff:
---
libstdc++-v3/include/std/format | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 46bd5d5ee6a0..5749aa1995a9 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -2998,11 +2998,9 @@ namespace __format
};
#endif
-#if defined(__SIZEOF_FLOAT128__) && _GLIBCXX_FORMAT_F128 > 1
- // Reuse __formatter_fp<C>::format<__format::__flt128_t, Out> for __float128.
- // This formatter is not declared if _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT is
true,
- // as __float128 when present is same type as __ieee128, which may be same as
- // long double.
+#if defined(__SIZEOF_FLOAT128__) && _GLIBCXX_FORMAT_F128 == 2
+ // Use __formatter_fp<C>::format<__format::__flt128_t, Out> for __float128,
+ // when long double is not 128bit IEEE type.
template<__format::__char _CharT>
struct formatter<__float128, _CharT>
{
@@ -3020,9 +3018,6 @@ namespace __format
private:
__format::__formatter_fp<_CharT> _M_f;
-
- static_assert( !is_same_v<__float128, long double>,
- "This specialization should not be used for long double" );
};
#endif
