rust-mode and lsp-mode setup for emacs

rust.el

;;; rust
(use-package rust-mode
  :ensure t
  :hook ((rust-mode . flycheck-mode)
	       (rust-mode . hs-minor-mode))
  :bind (:map rust-mode-map
	      ("<f6>" . my/rust-format-buffer)
	      ("C-c 6" . my/rust-format-buffer))
  :config
  (require 'rust-rustfmt)
  (defun my/rust-format-buffer ()
    (interactive)
    (rust-format-buffer)
    (save-buffer)))

;;; lsp
(use-package lsp-mode
  :ensure t
  :hook ((rust-mode      . lsp-deferred)
	       (go-mode        . lsp-deferred)
	       (f90-mode       . lsp-deferred)
	       (c++-mode       . lsp-deferred)
	       (fortran-mode   . lsp-deferred))
  :bind (:map lsp-mode-map
	      ("C-c d" . lsp-describe-thing-at-point)
	      ("C-c a" . lsp-execute-code-action)
	      ("C-c f" . flycheck-list-errors))
  :config
  ;; rust
  (require 'lsp-rust)
  (setq lsp-rust-analyzer-completion-add-call-parenthesis nil
	      lsp-rust-analyzer-proc-macro-enable t
	      lsp-rust-analyzer-cargo-watch-command "clippy")

  ;; general
  (define-key lsp-mode-map (kbd "C-c l") lsp-command-map)
  (lsp-enable-which-key-integration t)
  (setq lsp-enable-links nil
	      lsp-keep-workspace-alive nil)
  (cl-defmethod lsp-clients-extract-signature-on-hover
    (contents (_server-id (eql rust-analyzer)))
    "from https://github.com/emacs-lsp/lsp-mode/pull/1740 to extract
signature in rust"
    (-let* (((&hash "value") contents)
	    (groups (--partition-by (s-blank? it) (s-lines (s-trim value))))
	    (sig_group (if (s-equals? "```rust" (car (-third-item groups)))
			   (-third-item groups)
			 (car groups)))
	    (sig (--> sig_group
		      (--drop-while (s-equals? "```rust" it) it)
		      (--take-while (not (s-equals? "```" it)) it)
		      (--map (s-trim it) it)
		      (s-join " " it))))
      (lsp--render-element (concat "```rust\n" sig "\n```")))))