https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117968
--- Comment #4 from Rémi MARSAL <d...@remi-marsal.com> --- Thanks for pointing out the man page Jakub. This makes sense now. Apologies about this report. However, I don't understand why cpp doesn't raise an error because the input file doesn't exist. I recursively run a malformed cpp command on a "mock" project folder, and it disappeared.