linux-kernel - Re: [PATCH] objtool: Don't use -Werror

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Date:   Fri, 5 Apr 2019 18:05:50 +0200
From:   Luis Ressel <aranea@...ah.de>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        open list <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH] objtool: Don't use -Werror

On Fri, Apr 05, 2019 at 09:39:26AM -0500, Josh Poimboeuf wrote:

> Hm, I would actually argue the reverse.  Warnings are generally bad and
> -Werror is useful for ensuring that we don't have any.  For warnings
> that don't provide value, we just disable those individual warnings.

Sure, during development it's an excellent idea to investigate compiler
warnings, and -Werror can be useful for that. But the Linux kernel is
built by countless users in wildly varying environments, and it's almost
a given that someone will use a compiler that'll complain about a valid
part of your code whose style it considers bad.

As an example, the warning that's breaking the build for me is -Wundef
complaining about several "#if UNDEFINED_IDENTIFIER" constructs in the
libelf headers. (I agree with gcc in considering this bad style, but
it's perfectly valid C, and there probably wasn't a warning about it
back when this header was written.)

Regards,
Luis