[Bug libstdc++/21769] per-file control over PCH inclusion

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21769

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:91315f23ba127ea4d1a584023bae34e143f6eb8c

commit r14-3276-g91315f23ba127ea4d1a584023bae34e143f6eb8c
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Aug 16 21:46:05 2023 +0100

    libstdc++: Fix testsuite no_pch directive

    The { dg-add-options no_pch } directive is supposed to add a macro
    definition that invalidates the PCH file, and ensures that the #include
    directives in the test file are processed as written. But the proc that
    adds the options actually removes all existing options, cancelling out
    any previous dg-options directive.

    This means that using no_pch will cause FAILs in a file that relies on
    other options set by an earlier dg-options.

    The no_pch directive was added for PR libstdc++/21769 where Janis
    suggested adding it as return "$flags -D__GLIBCXX__=99999999" but what
    was actually committed didn't include the $flags so replaced them.

    Additionally, using no_pch  only prevents the precompiled version of
    <bits/stdc++.h> from being included, it doesn't prevent the
    non-precompiled version being included by -include bits/stdc++.h in the
    test flags. Use regsub to filter that out of the options as well.

    libstdc++-v3/ChangeLog:

            * testsuite/lib/dg-options.exp (add_options_for_no_pch): Remove
            any "-include bits/stdc++.h" from options and add the macro to
            the existing options instead of replacing them.