I plan to push this to trunk soon.
CC HP for visibility of the change affecting cris-elf. In practice it
shouldn't make any difference to any sensible code. It only affects
C++20 mode (and later), and only changes the size of std::formatter
objects which are typically only created by the library headers
themselves, and only on the stack (when using std::format and other new
C++20 APIs related to it).
-- >8 --
This ensures that the unused bits will be zero-initialized reliably, and
so can be used later by assigning them values in formatter
specializations. For example, formatters for std::chrono will need to
use an extra bit for a boolean to optimize the conversions between
locale encodings and UTF-8.
This will result in an ABI change for targets that use 1-byte alignment
for all integral types, e.g. cris-elf. We can't do that once C++20
support is non-experimental and ABI stable, so do it now before GCC 14
is released.
libstdc++-v3/ChangeLog:
* include/std/format (__format::_Spec::_M_reserved): Define a
new bit-field member in place of padding bits.
---
libstdc++-v3/include/std/format | 1 +
1 file changed, 1 insertion(+)
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 0eca8b58bfa..6c958bc11a5 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -406,6 +406,7 @@ namespace __format
_WidthPrec _M_width_kind : 2;
_WidthPrec _M_prec_kind : 2;
_Pres_type _M_type : 4;
+ unsigned long _M_reserved : 17;
unsigned short _M_width;
unsigned short _M_prec;
char32_t _M_fill = ' ';
--
2.43.0
