Comment by rumanator

> What build systems get wrong f

Build systems are not getting anything wrong. You're just struggling with a bunch of misconceptions about what a build system is and does, and what role a compiler plays in the whole process.

> is that the compiler has hidden inputs

There are no hidden inputs. There are only the compiler settings and project configs, and even the choice of compiler, which are all managed and set by the build system, and then there is the source code.

That's it.