[eridius]

Don't forget, Rust is written in Rust, so if you want to compile Rust from source because you don't trust the precompiled toolchain, you're in for a very long and arduous journey all the way back to the last version of the compiler written in OCaml, and then compiling a bunch of intermediate compiler versions using the previously-compiled version to inch your way towards the current version.

I'm not even sure how many intermediate compilers you'll have to compile to do this, it will take a lot of trial-and-error due to the compiler's own sources relying on features or bugfixes from previous versions of the compiler.

[pjtr]

Can't you use this "alternative rust compiler. Capable of building a fully-working copy of rustc" https://github.com/thepowersgang/mrustc and a trusted C++ compiler instead?

[steveklabnik]

Yes, that would work as well.

[irishsultan]

And if you are really paranoid you would need to audit the code of the compiler in every intermediate step.

[steveklabnik]

It’s around a thousand builds.

[eridius]

I'm honestly kind of surprised someone's actually gone through the effort of figuring that out, and I'm afraid to ask how long it takes to build the whole chain.

[steveklabnik]

There used to be a file that contained the SHA-1 hashes of the entire bootstrap chain; this is before we went with "rust 1.x builds with rust 1.(x - 1)". so i just counted. About 300 of them, three builds per bootstrap chain, plus some extra for all of the versions since we switched over.

I don't think anyone has actually done so, so I'm not sure how long, but probably a very, very long time. And you can't parallel it.