[Bug c++/115335] New: std::span at method is missing feature test macro __cpp_lib_span >= 202311L

[Bug c++/115335] New: std::span at method is missing feature test macro __cpp_lib_span >= 202311L

[gcc at ebasoft dot com.pl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115335

            Bug ID: 115335
           Summary: std::span at method is missing feature test macro
                    __cpp_lib_span >= 202311L
           Product: gcc
           Version: 14.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at ebasoft dot com.pl
  Target Milestone: ---

gcc (Gentoo 14.1.1_p20240518 p1) 14.1.1 20240516
In gcc stdlibc++ 14 there is method span<>::at added that should be visible
only to standard c++26.
https://en.cppreference.com/w/cpp/container/span/at

But implementation is missing feature test macro
__cpp_lib_span >= 202311L and this method is visible for all standards backward
in c++20 and c++23.
availability in backward standards makes difficult to refactor code for example
from vector to span that will be still portable with older gcc like 13 when it
is being done on platform with gcc libstdc++ 14 as there is no compiler error
when method at is being used after refactoring vector to span.

[Bug libstdc++/115335] std::span at method is missing feature test macro __cpp_lib_span >= 202311L

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115335

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-06-04
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I updated the macro value but seem to have forgotten to check it in <span>

[Bug libstdc++/115335] std::span at method is missing feature test macro __cpp_lib_span >= 202311L

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115335

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:2197814011eec75022aa8550f10621409b69d4a1

commit r15-1015-g2197814011eec75022aa8550f10621409b69d4a1
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Jun 4 15:06:44 2024 +0100

    libstdc++: Only define std::span::at for C++26 [PR115335]

    In r14-5689-g1fa85dcf656e2f I added std::span::at and made the correct
    changes to the __cpp_lib_span macro (with tests for the correct value in
    C++20/23/26). But I didn't make the declaration of std::span::at
    actually depend on the macro, so it was defined for C++20 and C++23, not
    only for C++26. This fixes that oversight.

    libstdc++-v3/ChangeLog:

            PR libstdc++/115335
            * include/std/span (span::at): Guard with feature test macro.

[Bug libstdc++/115335] std::span at method is missing feature test macro __cpp_lib_span >= 202311L

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115335

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-14 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:c6e6258ea43299399074f8d5f48697b5bc26064e

commit r14-10281-gc6e6258ea43299399074f8d5f48697b5bc26064e
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Jun 4 15:06:44 2024 +0100

    libstdc++: Only define std::span::at for C++26 [PR115335]

    In r14-5689-g1fa85dcf656e2f I added std::span::at and made the correct
    changes to the __cpp_lib_span macro (with tests for the correct value in
    C++20/23/26). But I didn't make the declaration of std::span::at
    actually depend on the macro, so it was defined for C++20 and C++23, not
    only for C++26. This fixes that oversight.

    libstdc++-v3/ChangeLog:

            PR libstdc++/115335
            * include/std/span (span::at): Guard with feature test macro.

    (cherry picked from commit 2197814011eec75022aa8550f10621409b69d4a1)

[Bug libstdc++/115335] std::span at method is missing feature test macro __cpp_lib_span >= 202311L

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115335

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |14.2
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed for 14.2, thanks for the report.