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 <lhy...@gcc.gnu.org>: https://gcc.gnu.org/g:9938645fcf914ec2a3fa8137cf1456ad4af5f77c commit r14-5471-g9938645fcf914ec2a3fa8137cf1456ad4af5f77c Author: Lewis Hyatt <lhy...@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.