Arsen Arsenović via Libstdc++ <libstdc++@gcc.gnu.org> writes:

> Good idea.  Both the positive and negative cases work when implemented
> like this:
>
> From 98d302bab9a87d3f2daecf9d54d62f33ba216673 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?Arsen=20Arsenovi=C4=87?= <arsen@aarsen.me>
> Date: Wed, 8 Mar 2023 17:01:24 +0100
> Subject: [PATCH 2/4] libstdc++: Add a test for <version> FTM redefinitions
>
> This test detects redefinitions by compiling stdc++.h with
> -Wsystem-headers.  Thanks Patrick Palka for the suggestion.
>
> libstdc++-v3/ChangeLog:
>
> 	* testsuite/17_intro/versionconflict.cc: New test.

I've forgotten to reword this after changing the logic.  New message:

commit dcd7bed33cc274e8f3565ad02fb1fbc04bc845fb
Author: Arsen Arsenović <arsen@aarsen.me>
Date:   Wed Mar 8 17:01:24 2023 +0100

    libstdc++: Add a test for <version> FTM redefinitions
    
    This test detects redefinitions by compiling stdc++.h and <version>,
    by disabling the system_header pragma on the latter, to allow
    warnings in it.  Thanks Patrick Palka for the suggestion.
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/17_intro/versionconflict.cc: New test.


-- 
Arsen Arsenović