[anth_anm]

Nope, loads of build tools were never built with reproducibility in mind.

Look at windows. Even if you fix the compiler and linker, you still non-reproducibility by design, the PE header contains a timestamp.

People also like to stick non-reproducible stuff into builds directly, like timestamps.

Compilers don't have any reason to lay down data in a specific order, so if they are threaded in the backend they just don't.

IDL tools might stick in the timestamp of when a file was generated, for convenience.

and on and on and on.