[Bug pch/47857] Pragma once warning when compiling PCH

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47857

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Lewis Hyatt <lhyatt@gcc.gnu.org>:

https://gcc.gnu.org/g:9938645fcf914ec2a3fa8137cf1456ad4af5f77c

commit r14-5471-g9938645fcf914ec2a3fa8137cf1456ad4af5f77c
Author: Lewis Hyatt <lhyatt@gmail.com>
Date:   Fri Nov 10 11:10:18 2023 -0500

    c-family: Let libcpp know when the compilation is for a PCH [PR9471]

    libcpp will generate diagnostics when it encounters things in the main file
    that only belong in a header file, such as `#pragma once' or `#pragma GCC
    system_header'. But sometimes the main file is a header file that is just
    being compiled separately, e.g. to produce a C++ module or a PCH, in which
    case such diagnostics should be suppressed. libcpp already has an interface
    to request that, so make use of it in the C frontends to prevent libcpp
from
    issuing unwanted diagnostics when compiling a PCH.

    gcc/c-family/ChangeLog:

            PR pch/9471
            PR pch/47857
            * c-opts.cc (c_common_post_options): Set cpp_opts->main_search
            so libcpp knows it is compiling a header file separately.

    gcc/testsuite/ChangeLog:

            PR pch/9471
            PR pch/47857
            * g++.dg/pch/main-file-warnings.C: New test.
            * g++.dg/pch/main-file-warnings.Hs: New test.
            * gcc.dg/pch/main-file-warnings.c: New test.
            * gcc.dg/pch/main-file-warnings.hs: New test.