[Bug preprocessor/60723] Line directives with incorrect system header flag

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60723

--- Comment #28 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
If this is about ccache, I wonder if ccache couldn't preprocess with
-fdirectives-only instead, that way hopefully no info is lost.