I have been thinking about Rust bootstrapping recently. Couldn't a Rust compiler without borrow checker be put together relatively easily?

Assuming the source code contains no issues (which can be checked later once the Rust compiler is built), one could leave that piece behind, and take the shortest path from .rs to executed code (C transpilation, or even an interpreter).

This exists: https://github.com/thepowersgang/mrustc.