Emacs ruff flycheck config

flycheck-ruff.el

(require 'flycheck)

;; From https://github.com/flycheck/flycheck/issues/1974#issuecomment-1343495202
(flycheck-define-checker python-ruff
  "A Python syntax and style checker using the ruff utility.
To override the path to the ruff executable, set
`flycheck-python-ruff-executable'.
See URL `http://pypi.python.org/pypi/ruff'."
  :command ("ruff"
            "--format=text"
            (eval (when buffer-file-name
                    (concat "--stdin-filename=" buffer-file-name)))
            "-")
  :standard-input t
  :error-filter (lambda (errors)
                  (let ((errors (flycheck-sanitize-errors errors)))
                    (seq-map #'flycheck-flake8-fix-error-level errors)))
  :error-patterns
  ((warning line-start
            (file-name) ":" line ":" (optional column ":") " "
            (id (one-or-more (any alpha)) (one-or-more digit)) " "
            (message (one-or-more not-newline))
            line-end))
  :modes python-mode)

;; Use something adapted to your config to add `python-ruff' to `flycheck-checkers'
;; This is an MVP example:
(setq python-mode-hook
      (list (defun my-python-hook ()
              (unless (bound-and-true-p org-src-mode)
                (when (buffer-file-name)
                  (setq-local flycheck-checkers '(python-ruff))
                  (flycheck-mode))))))

FYI newest Ruff seems to want to be called like ruff check --output-format=text .... Everything else worked. Thank you for this!

I've got an updated version I'm using today (for the first time—but it seems OK so far) here.