Re: _AC_PROG_CXX_CXX11 is broken in C++20

On 1/6/26 14:16, Bruno Haible wrote:
>    - AC_PROG_CXX        should not change the CXX variable.
>    - AC_PROG_CXX([98])  should not change the CXX variable.
>    - AC_PROG_CXX([11])  should try the -std=gnu++11 option and, if it is needed
>                         and it works, add it to the CXX variable.
>    - AC_PROG_CXX([17])  should try the -std=gnu++17 option and, if it is needed
>                         and it works, add it to the CXX variable.
>    - AC_PROG_CXX([20])  should try the -std=gnu++20 option and, if it is needed
>                         and it works, add it to the CXX variable.
>    - AC_PROG_CXX([23])  should try the -std=gnu++23 option and, if it is needed
>                         and it works, add it to the CXX variable.
>    - AC_PROG_CXX([26])  should try the -std=gnu++26 option and, if it is needed
>                         and it works, add it to the CXX variable.

This sounds like a good improvement to Autoconf. cc'ing bug-autoconf so 
that it gets recorded there. For Autoconf readers: the thread starts here:

https://lists.gnu.org/r/bug-gnulib/2026-01/msg00030.html