https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66277
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED CC| |jakub at gcc dot gnu.org Resolution|--- |INVALID --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Seems to be a user error. Just read man page of cpp and gcc, the former accepts (besides options) just two arguments, infile and outfile, while grub clearly relies on $(CPP) being able to preprocess many source files at the same time. That is gcc -E, not cpp (and if you don't override it from the command line, that is indeed what the configure will do correctly automatically).