Add Flycheck and Flymake for error reporting (#109)

* feat: define a flycheck checker

* feat: add flymake support

* feat: only report message if other backends aren't running

* chore: update DS_Store

* chore: add documentation on error reporting with flycheck and flymake

.gitignore

@@ -1,3 +1,4 @@
 elpa-emacs
 .cask/*
-.node_modules/
+.node_modules/
+.DS_Store

parinfer-rust-flycheck.el

@@ -0,0 +1,72 @@
+;;; parinfer-rust-flycheck.el --- Flycheck integration for parinfer-rust-mode   -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2024  Justin Barclay
+
+;; Author: Justin Barclay <[email protected]>
+
+;; This program is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+;; This file is not part of GNU Emacs.
+
+;;; Commentary:
+;; An assortment of helper functions and ports of functions from Emacs
+
+;;; Code:
+(eval-when-compile
+  (declare-function flycheck-error-new-at "flycheck")
+  (declare-function flycheck-define-generic-checker "flycheck")
+  (defvar parinfer-rust--error nil))
+
+(require 'flycheck nil t)
+
+(defun parinfer-rust--flycheck-start (checker callback)
+  (funcall callback 'finished
+           (when-let ((error parinfer-rust--error))
+             (list
+              (flycheck-error-new-at
+               (+ 1 (plist-get error :line_no))
+               (+ 1 (plist-get error :x))
+               'error
+               (plist-get error :message)
+               :id (plist-get error :name)
+               :checker checker)))))
+
+(flycheck-define-generic-checker 'parinfer-rust
+    "A checker for parinfer-rust."
+    :start 'parinfer-rust--flycheck-start
+    :verify (lambda (&rest args)
+              (list (flycheck-verification-result-new
+                     :label "parinfer-rust-mode"
+                     :message (if parinfer-rust-mode
+                                  "enabled"
+                                "not enabled"))))
+    :modes '(clojure-mode
+             clojurec-mode
+             clojurescript-mode
+             clojure-ts-mode
+             clojure-ts-clojurescript-mode
+             janet-mode
+             common-lisp-mode
+             lisp-mode
+             racket-mode
+             scheme-mode
+             lisp-interaction-mode
+             emacs-lisp-mode))
+
+(flycheck-add-next-checker 'emacs-lisp 'parinfer-rust t)
+
+(add-to-list 'flycheck-checkers 'parinfer-rust t)
+
+(provide 'parinfer-rust-flycheck)
+;;; parinfer-rust-flycheck.el ends here

parinfer-rust-flymake.el

@@ -0,0 +1,53 @@
+;;; parinfer-rust-flymake.el --- Flymake integration for parinfer-rust-mode   -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2024  Justin Barclay
+
+;; Author: Justin Barclay <[email protected]>
+
+;; This program is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+;; This file is not part of GNU Emacs.
+
+;;; Commentary:
+;;
+
+;;; Code:
+
+(require 'flymake)
+
+(eval-when-compile
+  (defvar parinfer-rust--error nil))
+
+(defun parinfer-rust-flymake (report-fn &rest _args)
+  (funcall report-fn
+           (when-let ((error parinfer-rust--error))
+             (list
+              (let ((loc (flymake-diag-region
+                          (current-buffer)
+                          (+ 1 (plist-get error :line_no))
+                          (+ 1 (plist-get error :x)))))
+                (flymake-make-diagnostic
+                 (current-buffer)
+                 (car loc)
+                 (cdr loc)
+                 :error
+                 (plist-get error :message)))))))
+
+(defun parinfer-rust-setup-flymake ()
+  (add-hook 'flymake-diagnostic-functions 'parinfer-rust-flymake nil t))
+
+(add-hook 'parinfer-rust-mode-hook 'parinfer-rust-setup-flymake)
+
+(provide 'parinfer-rust-flymake)
+;;; parinfer-rust-flymake.el ends here

parinfer-rust-mode.el

@@ -407,6 +407,12 @@ See `parinfer-rust--option-type' for a more complete explanation of the options.
 (require 'subr-x)
 (require 'font-lock)
 
+(with-eval-after-load 'flycheck
+  (require 'parinfer-rust-flycheck))
+
+(with-eval-after-load 'flymake
+  (require 'parinfer-rust-flymake))
+
 (defconst parinfer-rust--mode-types '("indent" "smart" "paren")
   "The different modes that parinfer can operate on.")
 
@@ -620,10 +626,16 @@ CHANGES."
         (when (and (local-variable-if-set-p 'parinfer-rust--in-debug)
                    parinfer-rust--in-debug)
           (parinfer-rust-debug "./parinfer-rust-debug.txt" options answer))
-        (if parinfer-error
+        (setq parinfer-rust--error parinfer-error)
+        ;; If we have an error and are not being reported by a backend, warn the user
+        (if (and parinfer-error
+                 (not (and (boundp 'flycheck-mode)
+                           (memq 'parinfer-rust flycheck--automatically-enabled-checkers)))
+                 (not (and (boundp 'flymake-mode)
+                          (memq 'parinfer-rust-flymake (flymake-reporting-backends)))))
             (message "Problem on line %s: %s"
              (plist-get parinfer-error :line_no)
-             (plist-get parinfer-error :message)) ;; TODO - Handler errors
+             (plist-get parinfer-error :message))
           ;; This stops Emacs from flickering when scrolling
           (if (not (string-equal parinfer-rust--previous-buffer-text replacement-string))
               (save-mark-and-excursion

readme.org

@@ -220,6 +220,21 @@ Options:
   #+begin_quote
   default: safe
   #+end_quote
+** Error reporting
+parinfer-rust-mode uses flycheck and flymake to report parsing errors.
+*** Flymake
+There should be no config needed to work in ==flymake-mode== is enabled.
+*** Flycheck
+parinfer-rust-mode is set-up to be chained with the ==emacs-lisp== checker.
+
+However, if you want it to work alongside other checkers you'll need to [[https://www.flycheck.org/en/latest/user/syntax-checkers.html#configuring-checker-chains][chain]] it yourself.
+#+begin_src emacs-lisp
+  (use-package parinfer-rust-mode
+    :config
+    (flycheck-add-next-checker 'emacs-lisp 'parinfer-rust t))
+#+end_src
+*** Message buffer
+If neither Flycheck or Flymake are enabled then ==parinfer-rust-mode== will output the error to ==*Messages*== buffer.
 ** parinfer-mode
    There is an alternate implementation of Parinfer for Emacs called [[https://github.com/DogLooksGood/parinfer-mode][parinfer-mode]]. It currently has support for Parinfer's "paren" and "indent". Additionally, it has had experimental support for "smart" mode, however, this has remained hidden on a branch and not accessible from MELPA for over a year.
    parinfer-smart-mode aims to be a simpler adaptation of Parinfer that just offers "smart mode", leveraging the parinfer-rust plugin to do most of the heavy lifting.