On Wednesday, 18 September 2013 at 16:25:16 UTC, Dicebot wrote:
> You can get this information from gcc and use it to define 100% correct dependencies. However, it highlights another issue common for build tools not coupled with compiler - to generate dependency graph reliably you need now to parse all the source files which contradicts one of core motivations to do it. The way C preprocessor works does not help the matter either.

The idea is to cache the dependencies to not reparse everything.