15 apr. 2022 kl. 17.23 skrev Werner LEMBERG <wl@gnu.org>:

>> It seems likely that this version has __clang_major__ = 4 despite
>> begin based on 3.2; if so, then the attached change may be the right
>> solution.  Would you give it a try?
> 
> This helps, thanks.

Thanks for testing. Paul, would you consider something like that patch (repeated here) for gnulib?
This is likely a regression in Emacs 28.1 for Werner's build environment.