[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260
Jonathan Wakely changed:
What|Removed |Added
Status|WAITING |NEW
--- Comment #8 from Jonathan Wakely ---
Since GCC 13 you can use _Float128 in older -std modes, and prior to GCC 13
there's no chance we're going to add this anyway.
The only thing missing here is that the _Float128 overloads are not declared
before C++23. They do exist in the library though, so if we declared them they
would be usable:
#include
#if __cplusplus <= 202002L
namespace std
{
from_chars_result
from_chars(const char* __first, const char* __last, _Float128& __value,
chars_format __fmt = chars_format::general) noexcept;
to_chars_result
to_chars(char* __first, char* __last, _Float128 __value) noexcept;
}
#endif
int main()
{
char str[] = "0.5";
_Float128 d = 2.0;
std::to_chars(str, str+3, d);
std::from_chars(str, str+3, d);
}
We could also add inline overloads for __float128 that forward to the _Float128
functions. The difficulty would be detecting when that's safe to do. We only
define the _Float128 overloads when that type is supported, and every time we
touch the macros around this something breaks.
Confirming as an enhancement, but I don't intent to work on this myself.
[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260 --- Comment #7 from g.peterh...@t-online.de --- Thank you. That was my question whether these two functions could be added. At the moment I'm using boost.charconv https://github.com/cppalliance/charconv https://develop.charconv.cpp.al (not official yet) - but it's still completely buggy.
[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260 --- Comment #6 from Andrew Pinski --- (In reply to g.peterhoff from comment #5) > ??? I asked for std::from_chars/std::to_chars - which of course doesn't work: > https://godbolt.org/z/n34dTajoc std::from_chars/std::to_chars for extended floating point types is only available with C++23 though. I really doubt they will be added for __float128 . Maybe they could be enabled for pre-C++23 for the extended FP types too .. But a libstdc++ maintainer should answer that question since that would be an extension. Even having them for __float128 will be an extension too.
[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260 --- Comment #5 from g.peterh...@t-online.de --- ??? I asked for std::from_chars/std::to_chars - which of course doesn't work: https://godbolt.org/z/n34dTajoc
[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260 --- Comment #4 from Andrew Pinski --- _Float128 is supported in older c++ standards for gcc. That is it does not error out for -std=gnu++11 even.
[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260 --- Comment #3 from g.peterh...@t-online.de --- My problem is that I need from_chars/to_chars for __float128 also for older C++ standards that do not yet support _Float128/std::float128_t.
[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260 Andrew Pinski changed: What|Removed |Added Ever confirmed|0 |1 Last reconfirmed||2024-01-08 Status|UNCONFIRMED |WAITING --- Comment #2 from Andrew Pinski --- Actually it was added in GCC 13 by r13-3754-ge5bcbcd04cfcb2 . Can you provide more information here what you need? Using _Float128 is better than using __float128 since _Float128 is the C/C++ standard style of extended floating point types.
[Bug libstdc++/113260] missing from_chars/to_chars for __float128
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113260 --- Comment #1 from Andrew Pinski --- There is support for _Float128 for from_chars/to_chars in GCC 14 already ..
