https://www.rust-lang.org/tools/install
# .bash_profile
[ -f "$HOME/.cargo/env" ] && source "$HOME/.cargo/env"
rustup component add rust-src
git clone https://github.com/rust-analyzer/rust-analyzer.git
cd rust-analyzer
cargo xtask install --server
;; init.el
(use-package rustic
:ensure t
:config
(setq rustic-format-on-save t))