If you're writing your own compiler, I don't think the Ferrocene specification will help you. It's basically an old version of the Rust Reference written out i

If you're writing your own compiler, I don't think the Ferrocene specification will help you. It's basically an old version of the Rust Reference written out in a more bureaucratic manner. (I see a little new material, such as the Name Resolution subsection, but even that is incomplete and I think wrong.) Neither of these things is anywhere near close enough to being complete and correct to implement a compiler against.