[rfoo]

Unfortunately, if we take this definition of "anything" literally, it is impossible to build such a build system.

For example, depending on the input order, linker may produce different output. Surely you can sort the object files, but the sorted object files order is still effectively "stored" into the binary, and that's not source code.

You can only normalize such things (like in the example above, sorting), you can not eliminate them, they naturally exist.

[rbanffy]

> you can sort the object files, but the sorted object files order is still effectively "stored" into the binary, and that's not source code.

No, but the order should be explicitly defined in the build scripts or the result will not be deterministic.

If the order triggers, say, a linker bug that makes one in 50 builds crash, execution will not be deterministic and that's really, really bad.