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From: Jonathan Wakely <jwakely.gcc@gmail.com>
Date: Tue, 21 Jun 2022 20:35:07 +0100
Message-ID: <CAH6eHdTPPVQ3QrxSDfcU_L9emsUkeMVLUFYDO49hmPV=cnDYYw@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 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.