> These files are created even without this argument That used to be the case in the dark ages of autoconf. clang does everything in a single address space wh

> These files are created even without this argument That used to be the case in the dark ages of autoconf. clang does everything in a single address space which is a lot faster now that you aren't doing a million filesystem calls. btw I remember seeing a talk a few years ago about integrating clang with the build system so that the same compiler process can be reused to compile multiple files. Startup time is significant when you have a lot of source files Past: >1 process and many fs calls per cpp. Present: 1 process and a few fs calls per cpp. Future: <1 process and a few fs calls per cpp (on average)