feat(emacs): integrate lean-next-error-mode

src/emacs/lean-flycheck.el

@@ -49,6 +49,7 @@
        (flycheck-sanitize-errors (flycheck-increment-error-columns errors)))
     :modes '(lean-mode))
   (add-to-list 'flycheck-checkers 'lean-checker))
+(flycheck-def-executable-var "lean-checker" (lean-get-executable lean-flycheck-checker-name))
 
 (defun lean-flycheck-turn-on ()
   (interactive)
@@ -119,4 +120,64 @@
       lean-flycheck-msg-width)
      (t (- (lean-flycheck-error-list-buffer-width) other-columns-width margin)))))
 
+(defconst lean-next-error-buffer-name "*Lean Next Error*")
+
+(defun lean-next-error-copy ()
+  (when (and (equal major-mode 'lean-mode)
+             ;; HACK -- princ-ing to another buffer seems to remove the marker
+             (not mark-active))
+
+    (let* ((errors (sort (flycheck-overlay-errors-in (line-beginning-position) (line-end-position)) #'flycheck-error-<))
+           (buffer (get-buffer lean-next-error-buffer-name))
+           ;; output logic taken from with-temp-buffer-window, but don't reset major mode
+           (standard-output buffer))
+
+      ;; prefer error of current position, if any
+      (-if-let (e (get-char-property (point) 'flycheck-error))
+          (setq errors (list e)))
+
+      ;; fall back to next error
+      (if (null errors)
+          (-if-let* ((pos (flycheck-next-error-pos 1))
+                     (e (get-char-property pos 'flycheck-error)))
+              (setq errors (list e))))
+
+      (with-current-buffer buffer
+        (setq buffer-read-only nil)
+        (erase-buffer))
+
+      (if errors
+          (dolist (e errors)
+            (princ (format "%d:%d: " (flycheck-error-line e) (flycheck-error-column e)))
+            (princ (flycheck-error-message e))
+            (princ "\n\n"))
+        (if flycheck-current-errors
+            (princ (format "(%d more messages above...)" (length flycheck-current-errors)))))
+
+      (temp-buffer-window-show buffer))))
+
+(define-minor-mode lean-next-error-mode
+  "Toggle lean-next-error-mode on and off.
+lean-next-error-mode takes the next error (or all errors of the current line, if any) from
+flycheck and shows them in a dedicated buffer set to `lean-info-mode'."
+  :group 'lean
+  :global t
+  (let ((hooks '(flycheck-after-syntax-check-hook post-command-hook)))
+    (if lean-next-error-mode
+        (progn
+
+          (unless (get-buffer lean-next-error-buffer-name)
+            (with-current-buffer (get-buffer-create lean-next-error-buffer-name)
+              (lean-info-mode)))
+
+          (dolist (hook hooks)
+            (add-hook hook 'lean-next-error-copy))
+
+          (setq lean-next-error-old-display-function flycheck-display-errors-function
+                flycheck-display-errors-function nil))
+
+      (setq flycheck-display-errors-function lean-next-error-old-display-function)
+      (dolist (hook hooks)
+        (remove-hook hook 'lean-next-error-copy)))))
+
 (provide 'lean-flycheck)

src/emacs/lean-mode.el

@@ -237,6 +237,7 @@ placeholder, call lean-server with --hole option, otherwise call
   (local-set-key lean-keybinding-tab-indent-or-complete    'lean-tab-indent-or-complete)
   (local-set-key lean-keybinding-lean-show-goal-at-pos     'lean-show-goal-at-pos)
   (local-set-key lean-keybinding-lean-show-id-keyword-info 'lean-show-id-keyword-info)
+  (local-set-key lean-keybinding-lean-next-error-mode      'lean-next-error-mode)
   )
 
 (defun lean-define-key-binding (key cmd)
@@ -272,7 +273,9 @@ placeholder, call lean-server with --hole option, otherwise call
      ["Use flycheck (on-the-fly syntax check)"
       lean-toggle-flycheck-mode :active t :style toggle :selected flycheck-mode]
      ["Show type at point"
-      lean-toggle-eldoc-mode :active t :style toggle :selected eldoc-mode])
+      lean-toggle-eldoc-mode :active t :style toggle :selected eldoc-mode]
+     ["Show next error in dedicated buffer"
+      lean-next-error-mode :active t :style toggle :selected lean-next-error-mode])
     "-----------------"
     ["Customize lean-mode" (customize-group 'lean)            t]))
 

src/emacs/lean-settings.el

@@ -227,4 +227,7 @@ false (nil)."
 (defcustom lean-keybinding-lean-show-id-keyword-info (kbd "C-c C-p")
   "Lean Keybinding for show-id-keyword-info"
   :group 'lean-keybinding  :type 'key-sequence)
+(defcustom lean-keybinding-lean-next-error-mode (kbd "C-c C-n")
+  "Lean Keybinding for lean-next-error-mode"
+  :group 'lean-keybinding  :type 'key-sequence)
 (provide 'lean-settings)