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From: Jonathan Wakely <jwakely.gcc@gmail.com>
Date: Tue, 15 Nov 2022 19:27:55 +0000
Message-ID: <CAH6eHdTnMwkJi1fqo715KwJq1BsM9M=EkP4T1FMY0Kj9kf=8nQ@mail.gmail.com>
Subject: Re: How can Autoconf help with the transition to stricter compilation defaults?
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: Aaron Ballman <aaron@aaronballman.com>, Zack Weinberg <zack@owlfolio.org>, 
	c-std-porting@lists.linux.dev, autoconf@gnu.org, gcc@gcc.gnu.org, 
	cfe-commits@lists.llvm.org, Gnulib bugs <bug-gnulib@gnu.org>
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On Tue, 15 Nov 2022 at 19:08, Paul Eggert <eggert@cs.ucla.edu> wrote:
>
> On 2022-11-15 06:50, Jonathan Wakely wrote:
> > Could you clarify what you mean, with a concrete example? Surely as
> > long as errors are reported on stderr and the compiler exits with
> > non-zero status, that's an acceptable way to report errors?
>
> Not if the "error" is harmless as far as Autoconf is concerned, which is
> what led to this thread. The concrete example here is that Autoconf
> needs to check whether a function can be linked to (as opposed to
> checking the function's signature). Clang shouldn't get in the way.

Another perspective is that autoconf shouldn't get in the way of
making the C and C++ toolchain more secure by default.

>
> In lots of places the C standard says behavior is undefined, even though
> the behavior is fine on the current platform for the intended use. It's
> not just the example we're talking about; adding zero to a null pointer
> is another such example.
>
> In such cases it's OK for Clang to warn, but having Clang exit with
> nonzero status is overkill and counterproductive.