parser-lalr.y, parser-lalr-main.c, tokens.h and lexer.l are extracts from the more-complete rust-grammar repo: https://github.com/bleibig/rust-grammar
It is the most up-to-date grammar I’m aware of; everything pre-2015 – when the language underwent its final rush-to-stability – is probably junk due to constant grammar churn (all the ANTLR work is hopelessly bitrotted, and it’s not an appropriate tool anyways).
IMO Rust isn’t ideally thought of as LL(k) anymore; I tried to keep it that way for a long time, but it’s grown a lot of bits that work better in LR-family. I highly recommend just deleting anything ANTLR-related and focusing on LR(k) or LALR(k) grammars.
The verify.rs and testparser.py tools are components of the rust-grammar repo, but only parts; they’re intended to be used with the rlex / rparse stubs in that repo, that generate a comparable syntax tree dump from the production compiler. This is a reasonable approach to bringing a grammar-derived parser up to parity, but it’s bitrotted some. Also, of course, true lex-and-yacc are not likely the targets you want to stick with long term; they’re a stopgap.
Niko is working on https://github.com/nikomatsakis/lalrpop which should, eventually, be a good target for building an LR-family frontend for Rust, based on a grammar similar-to the one in the yacc file.