Re: GCC 7 warnings

[Eli Zaretskii <eliz@gnu.org>]

> Cc: emacs-devel@gnu.org, Richard Copley <rcopley@gmail.com>
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sat, 9 Sep 2017 11:27:40 -0700
> 
> There is a tradeoff for --enable-gcc-warnings. If we try to support ancient GCC 
> compilers, we'll have to complicate the code and consume scarce maintenance 
> resources. If we support only the latest GCC, developers using slightly-older 
> GCCs will get some annoying warnings when they use --enable-gcc-warnings. I 
> prefer to push the bleeding edge here, and ask developers who use 
> --enable-gcc-warnings to at most (say) a year-old GCC version, as this saves 
> some work for the rest of us. Of course we can't expect everybody to immediately 
> sync to the latest GCC when released, but on the other hand there is a cost to 
> supporting too-old GCCs, a cost I'd rather not pay (since I bear a good deal of 
> it...).

We already filter the warnings by GCC version.  We just needto filter
more, perhaps, and not just based on what GCC supports.

Since --enable-gcc-warnings is on by default for building the
development version, it needs to build relatively cleanly with a
reasonably recent GCC.  It's okay to have the code ready for the
bleeding edge, but if that triggers warnings with slightly older GCC,
it's counter-productive IMO, because asking developers to use GCC
which is too new might waste their time due to GCC bugs.  GCC 6 or 5
is not yet old enough to cause those who use them such trouble.

> By the way, I find the UNINIT macro to be more readable than supplying nonce 
> expressions, as UNINIT clearly indicates to the reader that the variable is 
> intended to be uninitialized.

This is a matter of personal style preferences.  I find the syntax of
UNINIT confusing, because it's not C-like.