How can Autoconf help with the transition to stricter compilation defaults?

[Zack Weinberg via cfe-commits]

On Tue, Nov 15, 2022, at 12:03 AM, Sam James wrote:
>> On 13 Nov 2022, at 00:43, Paul Eggert <eggert at cs.ucla.edu> wrote:
>> 
>> Although there will be problems with people who run "./configure CFLAGS='-Werror'", that sort of usage has always been problematic and unsupported by Autoconf, so we can simply continue to tell people "don't do that".
>> 
>
> Is there somewhere in the autoconf docs we actually say this?
>
> I've seen a few instances of folks adding it themselves very
> early in their configure scripts (which is a pain for distros
> anyway) which then ends up affecting the rest.

It's mentioned in the NEWS entry for 2.70: https://git.savannah.gnu.org/cgit/autoconf.git/tree/NEWS#n170

It should be discussed in the actual manual as well, but I've been reluctant to add anything about warnings to the manual as long as Autoconf proper doesn't have any support for controlling warnings.

Note that there have been bug reports for cases where running builds with more warnings than configure uses (and I think also -Werror), means that configure checks spuriously succeed (i.e. configure reports that something is available, but then you get compiler errors on the code that tries to use it).  I can't remember any concrete examples right now, though.

zw