[SAHChandler]

Forgive me, but I can't think of a single build system where the compiler is run on a source file twice. All of the ones I've seen support either parsing the .d file generated by a compiler, or parse /showIncludes if using MSVC. If you have any examples of build systems doing this, I'd love to see them so I can avoid them.

[dcohenp]

I've seen at least one, but it's proprietary and internal to my bigco. I'm willing to bet there's quite a few more at other bigcos. So lucky for you if you can avoid them, but I'm pretty sure there's many of us who don't get that choice.