At the moment your better off using the ra_lsp config from coc wiki. This repo is out of date with the upstream vscode extension. If your interested in getting this extension to work again, please send a PR.
This is a fork of the rust-analyzer VSCode extension for Coc.nvim
It runs, and thats about it. It is very buggy, but will be fixed by the time rust-analyzer it's self becomes usable.
git clone https://github.com/Avi-D-coder/coc-rust-analyzer.gitThen in (N)Vim:
CocInstall ./coc-rust-analyzer