[Bug libstdc++/110917] std::format_to(int*, ...) fails to compile because of _S_make_span
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110917 Jonathan Wakely changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #6 from Jonathan Wakely --- Fixed for 13.3, thanks for the report.
[Bug libstdc++/110917] std::format_to(int*, ...) fails to compile because of _S_make_span
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110917 --- Comment #5 from CVS Commits --- The releases/gcc-13 branch has been updated by Jonathan Wakely : https://gcc.gnu.org/g:0f0152a93d15b24ebc7f6c7455baaded6a63fb2e commit r13-7698-g0f0152a93d15b24ebc7f6c7455baaded6a63fb2e Author: Jonathan Wakely Date: Mon Aug 7 14:37:25 2023 +0100 libstdc++: Constrain __format::_Iter_sink for contiguous iterators [PR110917] We can't write to a span<_CharT> if the contiguous iterator has a value type that isn't _CharT. libstdc++-v3/ChangeLog: PR libstdc++/110917 * include/std/format (__format::_Iter_sink): Constrain partial specialization for contiguous iterators to require the value type to be CharT. * testsuite/std/format/functions/format_to.cc: New test. (cherry picked from commit c5ea5aecac323e9094e4dc967f54090cb244bc6a)
[Bug libstdc++/110917] std::format_to(int*, ...) fails to compile because of _S_make_span
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110917 --- Comment #4 from CVS Commits --- The master branch has been updated by Jonathan Wakely : https://gcc.gnu.org/g:c5ea5aecac323e9094e4dc967f54090cb244bc6a commit r14-3068-gc5ea5aecac323e9094e4dc967f54090cb244bc6a Author: Jonathan Wakely Date: Mon Aug 7 14:37:25 2023 +0100 libstdc++: Constrain __format::_Iter_sink for contiguous iterators [PR110917] We can't write to a span<_CharT> if the contiguous iterator has a value type that isn't _CharT. libstdc++-v3/ChangeLog: PR libstdc++/110917 * include/std/format (__format::_Iter_sink): Constrain partial specialization for contiguous iterators to require the value type to be CharT. * testsuite/std/format/functions/format_to.cc: New test.
[Bug libstdc++/110917] std::format_to(int*, ...) fails to compile because of _S_make_span
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110917 --- Comment #3 from Jonathan Wakely --- It fails for non-contrived cases like this too: char8_t buf[32]; std::format_to(buf, "");
[Bug libstdc++/110917] std::format_to(int*, ...) fails to compile because of _S_make_span
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110917 --- Comment #2 from Arthur O'Dwyer --- > Alternatively, we could replace the contiguous_iterator<_OutIter> constraint > with constructible_from, _OutIter, iter_difference_t<_OutIter>>. I think `is_same` is preferable to `constructible_from<...>` just because it's simpler; I wouldn't recommend the hairier thing unless there was a known reason for it. Doing the hairier thing would immediately trigger a search for the corner case where it would fail. ;) (Suppose the author of _OutIter arranges that sentinel_for — maybe that'd do the trick...) Btw, even though my reduced test case was contrived, it originates from an actually realistic use-case AFAIK: using `format` to format ASCII text automatically into an array of char16_t or char32_t (presumably on a platform with unsigned plain char).
[Bug libstdc++/110917] std::format_to(int*, ...) fails to compile because of _S_make_span
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110917
Jonathan Wakely changed:
What|Removed |Added
Status|UNCONFIRMED |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org
Last reconfirmed||2023-08-06
Target Milestone|--- |13.3
Ever confirmed|0 |1
--- Comment #1 from Jonathan Wakely ---
(In reply to Arthur O'Dwyer from comment #0)
> libc++ and Microsoft are both completely happy with this code. libstdc++ is
> happy with `f` but unhappy with `g`. I suspect that someplace is accepting
> "contiguous iterators of any old T" when it means to limit itself to
> "contiguous iterators of char" specifically.
Indeed, it's fixed by:
// not introduce any invalid pointer arithmetic or overflows that would not
// have happened anyway.
template
+requires same_as, _CharT>
class _Iter_sink<_CharT, _OutIter> : public _Sink<_CharT>
{
using uint64_t = __UINTPTR_TYPE__;
Alternatively, we could replace the contiguous_iterator<_OutIter> constraint
with constructible_from, _OutIter, iter_difference_t<_OutIter>>.
