Re: New warnings on emacs-26 branch with gcc 8.2.0

[Andy Moreton]

On Mon 06 Aug 2018, Paul Eggert wrote:

> Andy Moreton wrote:
>> I was hoping you could provide more background, as you are are shown as
>> the most recent committer of almost every line of configure.ac related
>> to warnings.
>
> Yes, I adapt this stuff for Emacs. However, it sounds like the part you want
> changed comes from a part of Gnulib that I do not know as well.
>
>> Is this problem arising from use of the gnulib manywarnings module ? If
>> so, why do we use it and not the simpler gnuslib warnings module ?
>
> The warnings module would require the hand-maintained Emacs source code to
> list the exact set of warnings that it wants, which would be a pain to
> maintain as the set commonly changes after each GCC release. The manywarnings
> module maintains such a list for us, which is simpler for Emacs proper (and
> allows us to share this mutating list among several GNU projects). The Emacs
> configure.ac tailors the Gnulib list a bit, but mostly leaves it alone; this
> is simpler for Emacs than maintaining its own sort-of-copy of the list by
> hand.

Using the manywarnings module still requires emacs to add new warnings to
the nw list every time gcc is upgraded, so I don't think that is less
work.

The manywarnings list also lists every conceivable warning, including
-Wall and -Wextra (why specify so many explicitly then?) and some that
are specific to C++ (why list them at all?).

It woudl surely be simpler to use _Wall -Wextra and a limited number of
additional warnings that know to be useful, rather than checking if every
warning is supported, even if they are unused and pointless.

    AndyM