alt Hacker NewsIs there, or could there be, a simple implementation of a compiler for the latest full Rust language (in C, Python, Scheme/Racket, or anything except Rust) that is greatly simplified because, although it accepts the latest full Rust language as input, it assumes the input is correct?
Could this simple non-checking Rust implementation transliterate the real Rust compiler's code, to unchecked C, that is good enough for that minimal-steps, sustainable bootstrapping?
This simple non-checking compiler only has to be able to compile one program, and only under controlled conditions, possibly only on hardware with a ton of memory.
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To some extent, sure - but Rust leans heavily on static analysis even for "simple" code. Something as fundamental as File::open is still generic over "types that can be coerced into a &Path" - which is obviously useful, but it probably means you would need to implement a lot of the type system (+ stubbed out borrow/reference semantics?) just to get rustc's parser bootstrapped.
This is actually tenable for C, though - so maybe you could cook up some sort of C -> C++ -> LLVM -> rustc bootstrap.
Rust can selfbootstrap by compiling the rust code for the compiler.
Is mrustc "simple" enough? Its purpose is as you describe, and it can bootstrap rustc to version 1.74.0. https://github.com/thepowersgang/mrustc