machine_setup/ansible/roles/emacs/files/lang-rust.el

(require 'common-lsp)
(require 'util-tree-sitter)

(defun locate-rust-analyzer ()
  "Find rust-analyzer."
  (let ((rust-analyzer-paths (list (locate-rust-analyzer-rustup) (locate-rust-analyzer-ansible-built))))
    (let ((first-non-nill-path (seq-find (lambda (elt) elt) rust-analyzer-paths)))
      first-non-nill-path
      )
    )
  )

(defun locate-rust-analyzer-rustup ()
  "Find rust-analyzer through rustup."
  (run-command-in-directory nil "rustup" "which" "rust-analyzer")
  )

(defun locate-rust-analyzer-ansible-built ()
  "Find rust-analyzer where the ansible playbook built it."
  (let ((rust-analyzer-path "/opt/rust-analyzer/target/release/rust-analyzer"))
    (when (file-exists-p rust-analyzer-path)
      rust-analyzer-path
      )
    )
  )

(use-package rust-mode
  :pin nongnu
  :mode "\\.rs\\'"
  :hook (
         (rust-ts-mode . (lambda ()
                        (eglot-ensure)
                        (let ((rust-analyzer-command (locate-rust-analyzer)))
                          (when rust-analyzer-command
                            (add-to-list 'eglot-server-programs (cons 'rust-ts-mode (list rust-analyzer-command)))
                            )
                          )
                        (add-hook 'before-save-hook 'eglot-format-buffer nil 'local)
                        ))
         )
  :init
  (add-to-list 'major-mode-remap-alist '(rust-mode . rust-ts-mode))
  (add-to-list 'treesit-language-source-alist '(rust "https://github.com/tree-sitter/tree-sitter-rust"))
  (unless (treesit-ready-p 'yaml) (treesit-install-language-grammar 'rust))
  :config
  ;; Add keybindings for interacting with Cargo
  (use-package cargo
    :hook (rust-ts-mode . cargo-minor-mode))
  )

(provide 'lang-rust)