Would it be possible for Rust to adopt an official grammar specification? It seems like right now, the implementation is the specification, which means you have to dive through dozens of files and thousands of lines of code to figure out what the syntax actually is.
The ungrammar that rust-analyzer uses can also be useful. It doesn't tell you how to parse the tokens, and it doesn't disambiguate anything, but it does a pretty good job at showing humans what the syntax of Rust looks like.