Re: [RFC PATCH] docs/style: permit inline loop variables

From: Peter Maydell <peter.maydell@linaro.org>
To: Markus Armbruster <armbru@redhat.com>
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
	qemu-devel@nongnu.org, "Daniel P. Berrangé" <berrange@redhat.com>,
	"Thomas Huth" <thuth@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	"Juan Quintela" <quintela@redhat.com>
Subject: Re: [RFC PATCH] docs/style: permit inline loop variables
Date: Thu, 24 Aug 2023 14:18:53 +0100	[thread overview]
Message-ID: <CAFEAcA8wobO5F16vYhbQCjeadfN5Zwx5CQ7L4vQ3fh8c_6ngJg@mail.gmail.com> (raw)
In-Reply-To: <87jztmz4bu.fsf@pond.sub.org>

On Wed, 23 Aug 2023 at 06:59, Markus Armbruster <armbru@redhat.com> wrote:
>
> Peter Maydell <peter.maydell@linaro.org> writes:
>
> > On Tue, 22 Aug 2023 at 16:50, Alex Bennée <alex.bennee@linaro.org> wrote:
> >> I've already wasted enough of my time debugging aliased variables in
> >> deeply nested loops.
> >
> > In theory we could try to enable -Wshadow and deal with
> > all the existing cases of aliasing, which would then
> > allow us to turn it into an error and catch your bugs :-)
>
> In practice, a quick compile with -Wshadow -Wno-error=shadow coughs up
> almost 6000 warnings.  There are duplicates since we compile many files
> multiple times, so I piped through sort -u | wc -l, and got about 1200.

-Wshadow=local has only 211 non-duplicate warnings, which
is almost tractable...

(A lot of the duplicates are from local variables declared in macros
like MAX(), MIN() and QOBJECT(), when those macros are used in a nested
way, like MIN(MIN(x,y),z). We could deal with those by using the
__COUNTER__ trick, I guess.)

-- PMM