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From: Jonathan Wakely <jwakely.gcc@gmail.com>
Date: Tue, 21 Jun 2022 20:47:49 +0100
Message-ID: <CAH6eHdR-oVQN-NYbdAnh9CGeF1V3iVr_WSX72qFTTrqdXnA=cg@mail.gmail.com>
Subject: Re: Narrowing down preprocessor-related potential defect
To: thutt <thutt@vmware.com>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
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On Tue, 21 Jun 2022, 20:35 Jonathan Wakely, <jwakely.gcc@gmail.com> wrote:

> On Tue, 21 Jun 2022 at 20:31, thutt--- via Gcc <gcc@gcc.gnu.org> wrote:
> >    I am here to solicit ideas on how to further narrow this this
> >    down.  Is there any undocumented option that I can use to cause the
> >    standalone preprocessor to produce output identical to input?
> >    Note that '-traditional-cpp' does not work because some of the code
> >    is not recognized (variadic macros, for example).
>
> This seems off-topic for the gcc mailing list. It belongs on the gcc-help
> list.
>
> Have you tried not using a standalone preprocessor?
>
> The usual approach is to add -save-temps to the gcc invocation, so it
> leaves the preprocessed output in a separate .i file.
>
> N.B. it's a warning, not an error. You told GCC to turn that warning
> into an error.
>


GCC has a whole guide to test case reduction here:
https://gcc.gnu.org/wiki/A_guide_to_testcase_reduction

I don't know how much will be applicable it usable in this instance.