Flycheck fails in an indirect region buffer

[bvraghav]

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Checklist

• I have checked existing issues for potential duplicates before creating this one.
• I have read the Troubleshooting guide.

Bug description

flycheck-eslint fails in an edit-indirect setting, maybe since there's no filename associated.

My guess is that because flycheck-eslint command is configured with

  :command ("eslint" "--format=json"
            (option-list "--rulesdir" flycheck-eslint-rules-directories)
            (eval flycheck-eslint-args)
            "--stdin" "--stdin-filename" source-original)

, the part where "--stdin-filename" source-original is hard-coded, source-original evaluates to nil in case of an indirect buffer causing the eslint executable to fail.

Steps to reproduce

In file ${PROJ}/tmp/foo.js flycheck-verify-setup gives

Syntax checkers for buffer foo.js in js2-mode:

First checker to run:

  javascript-eslint
    - may enable:  yes
    - executable:  Found at /XXXXXXXX/.config/nvm/versions/node/v18.14.2/bin/eslint
    - config file: found

In file ${PROJ}/tmp/foo.org, flycheck-verify-setup gives

Syntax checkers for buffer *Org Src foo.org[ js ]* in js2-mode:

First checker to run:

  javascript-eslint
    - may enable:  yes
    - executable:  Found at /XXXXXXXX/.config/nvm/versions/node/v18.14.2/bin/eslint
    - config file: found

But, at cursor position [I]

#+begin_src js
[I]
#+end_src

do C-c ' to edit indirect-ly as js buffer, and
flycheck fails with this this message

Suspicious state from syntax checker javascript-eslint: Flycheck checker javascript-eslint returned 2, but its output contained no errors: 
Oops! Something went wrong! :(

ESLint: 8.36.0

Error: 'options.filePath' must be a non-empty string or undefined
    at ESLint.lintText (/XXXXXXXX/.config/nvm/versions/node/v18.14.2/lib/node_modules/eslint/lib/eslint/eslint.js:583:19)
    at Object.execute (/XXXXXXXX/.config/nvm/versions/node/v18.14.2/lib/node_modules/eslint/lib/cli.js:412:36)
    at async main (/XXXXXXXX/.config/nvm/versions/node/v18.14.2/lib/node_modules/eslint/bin/eslint.js:135:24)

Try installing a more recent version of javascript-eslint, and please open a bug report if the issue persists in the latest release.  Thanks!

• I have read https://emacs.stackexchange.com/questions/28429/how-do-i-troubleshoot-emacs-problems

Expected behavior

I don't know for sure, but I guess that flycheck should send the buffer-contents as stdin, because there's no associated (buffer-file-name)

Screenshots

If applicable, add screenshots to help explain your problem.

System configuration

Syntax checkers for buffer *Org Src foo.org[ js ]* in js2-mode:

First checker to run:

  javascript-eslint
    - may enable:  yes
    - executable:  Found at /XXXXXXXXX/.config/nvm/versions/node/v18.14.2/bin/eslint
    - config file: found

Checkers that are compatible with this mode, but will not run until properly configured:

  javascript-jshint (automatically disabled) reset
    - may enable:         no
    - executable:         Not found
    - configuration file: Not found

  javascript-standard (automatically disabled) reset
    - may enable: no
    - executable: Not found

  javascript-tide
    - may enable:        yes
    - may run:           nil
    - Typescript server: not running
    - Tide mode:         disabled

Flycheck Mode is enabled.  Use C-u C-c ! x to enable
disabled checkers.

--------------------

Flycheck version: 33snapshot (package: 20230306.414)
Emacs version:    28.2
System:           x86_64-pc-linux-gnu
Window system:    x

Emacs configuration:

• Plain Emacs / Custom configuration
• Spacemacs
• Doom Emacs
• Other shared configuration

Additional notes

The difference in invoked flycheck-command

I had tried to get to the root cause using this step

(setq-local flycheck-command-wrapper-function (lambda (lst) (message "%s" lst) lst))

(/xxxxx/.config/nvm/versions/node/v18.14.2/bin/eslint --format=json --fix-dry-run --stdin --stdin-filename /home/rbv23/webr/vue-scratch/tmp/foo.js)

VS

(/xxxxx/.config/nvm/versions/node/v18.14.2/bin/eslint --format=json --stdin --stdin-filename )

[bvraghav]

I was able to cirvumvent the problem by customising the checker to use source instead of source-original

:command ("eslint" ;; ... 
          "--stdin" "--stdin-filename" source)

My complete customisation looks as follows. For some reason I ended up hard-coding the find-working-directory routine, which may not be necessary.

(defun bvr-flycheck-eslint--find-working-directory (_checker)
  "Look for a working directory to run ESLint CHECKER in.

This will be the directory that contains the `node_modules'
directory.  If no such directory is found in the directory
hierarchy, it looks first for `.eslintignore' and then for
`.eslintrc' files to detect the project root."
  (let* ((file (or (buffer-file-name) default-directory)))
    (when file
      (or (locate-dominating-file file "node_modules")
          (locate-dominating-file file ".eslintignore")
          (locate-dominating-file file ".eslintrc")
          (locate-dominating-file file ".eslintrc.js")
          (locate-dominating-file file ".eslintrc.json")
          (locate-dominating-file file ".eslintrc.yaml")
          (locate-dominating-file file ".eslintrc.yml")))))



(flycheck-define-checker bvr-javascript-eslint
  "A Javascript syntax and style checker using eslint.

See URL `https://eslint.org/'."
  :command ("eslint" "--format=json"
            (option-list "--rulesdir" flycheck-eslint-rules-directories)
            (eval flycheck-eslint-args)
            "--stdin" "--stdin-filename" source)
  :standard-input t
  :error-parser flycheck-parse-eslint
  :enabled (lambda () (flycheck-eslint-config-exists-p))
  :modes (js-mode js-jsx-mode js2-mode js2-jsx-mode js3-mode rjsx-mode
                  typescript-mode js-ts-mode typescript-ts-mode tsx-ts-mode)
  :working-directory bvr-flycheck-eslint--find-working-directory
  :verify
  (lambda (_)
    (let* ((default-directory
             (flycheck-compute-working-directory 'bvr-javascript-eslint))
           (have-config (flycheck-eslint-config-exists-p)))
      (list
       (flycheck-verification-result-new
        :label "config file"
        :message (if have-config "found" "missing or incorrect")
        :face (if have-config 'success '(bold error))))))
  :error-explainer
  (lambda (err)
    (let ((error-code (flycheck-error-id err))
          (url "https://eslint.org/docs/rules/%s"))
      (and error-code
           ;; skip non-builtin rules
           (not ;; `seq-contains-p' is only in seq >= 2.21
            (with-no-warnings (seq-contains error-code ?/)))
           `(url . ,(format url error-code))))))


(add-to-list 'flycheck-checkers 'bvr-javascript-eslint)

[bvraghav]

For posterity, I have created this simple workaround el.

https://github.com/bvraghav/dotelisp/blob/master/bvr-flycheck-eslint.el

And I leave it to the good judgement of maintainers to close this issue.