Re: [PATCH] Fix -Wmaybe-uninitialized warnings under -O0

[Jeff King <peff@peff.net>]

On Wed, Apr 01, 2020 at 03:30:16AM -0400, Denton Liu wrote:

> When compiling Git under -O0, gcc (Arch Linux 9.3.0-1) 9.3.0 produces
> many -Wmaybe-uninitialized warnings. These are false positives since
> when Git is compiled under -O2, gcc is smart enough to see that the
> code paths that use these variables all initialise them beforehand.
> Nonetheless, these warnings block the compilation process when
> DEVELOPER=1 is enabled (which enables -Werror).
> 
> Fix these warnings by initializing these variables with dummy values (0,
> -1 or NULL as appropriate).

Hmph. I almost always compile with -O0 and have been using gcc 9.3.0
since it was packaged for Debian a few weeks ago, but I don't see any of
these warnings.

The current version in Debian unstable is 9.3.0-8, which picks up some
extra patches from the upstream gcc-9 branch. But even if I download a
snapshot of the original 9.3.0 release, it builds fine.

So why does your version behave differently? And if this is a temporary
state for a buggy version of gcc (that may be fixed in the next point
release), is it worth changing our source code to appease it?

-Peff