After seeing http://gcc.gnu.org/ml/gcc-patches/2007-04/msg00829.html, I noticed that the actual compilers don't support the @file mechanism at all, so when people do -combine @file, we might overflow the argument list so we should support @file inside the compilers themselves besides just inside the driver. The easy fix is to this before calling toplevel_main.
-- Summary: cc1, cc1plus, etc. don't support @file mechanism Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: other AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: pinskia at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31567