bug#5911: flymake.el - enhancement request - flymake-goto-next-error should go to the column, if possible

bug#5911: flymake.el - enhancement request - flymake-goto-next-error should go to the column, if possible

[D Chiesa]

I use emacs v22.2.1 on Windows.

Flymake relies on compilation error patterns, similar to 
compilation-error-regexp-alist , to detect errors and warnings.
But flymake discards column information for any errors, and as a result, 
the functions flymake-goto-next-error and flymake-goto-prev-error do not 
position the cursor on the error column.

This discards useful information, and also makes it more difficult to add 
enhancements to flymake - such as the ability to offer a menu of "quick 
fixes" that can be applied on the spot, through 
flymake-display-err-menu-for-current-line .

The fix is to:

1- modify the flymake-ler struct, like so:

(defstruct (flymake-ler
            (:constructor nil)
            ;; cheeso = 2010 apr 8 - add col-no field
            (:constructor flymake-ler-make-ler (file line type text 
&optional full-file col-no)))
  file line type text full-file col-no)

2- modify the flymake-ler functions, accordingly

(defun flymake-ler-set-file (line-err-info file)
  (flymake-ler-make-ler file
                        (flymake-ler-line line-err-info)
                        (flymake-ler-type line-err-info)
                        (flymake-ler-text line-err-info)
                        (flymake-ler-full-file line-err-info)
                        ;; cheeso - 2010 apr 8
                        (flymake-ler-col-no line-err-info)
                        ))

(defun flymake-ler-set-full-file (line-err-info full-file)
  (flymake-ler-make-ler (flymake-ler-file line-err-info)
                        (flymake-ler-line line-err-info)
                        (flymake-ler-type line-err-info)
                        (flymake-ler-text line-err-info)
                        full-file
                        ;; cheeso - 2010 apr 8
                        (flymake-ler-col-no line-err-info)
                        ))

(defun flymake-ler-set-line (line-err-info line)
  (flymake-ler-make-ler (flymake-ler-file line-err-info)
                        line
                        (flymake-ler-type line-err-info)
                        (flymake-ler-text line-err-info)
                        (flymake-ler-full-file line-err-info)
                        ;; cheeso - 2010 apr 8
                        (flymake-ler-col-no line-err-info)
                        ))

3- modify   flymake-parse-line  to capture the column number, and store it 
in the flymake-ler struct that is created. (same as line-no, but use index 
3, instead of 2)

(defun flymake-parse-line (line)
  "Parse LINE to see if it is an error or warning.
Return its components if so, nil otherwise."
  (let ((raw-file-name nil)
        (line-no 0)
        (col-no 0)
        (err-type "e")
        (err-text nil)
        (patterns flymake-err-line-patterns)
        (matched nil))
    (while (and patterns (not matched))
      (when (string-match (car (car patterns)) line)
        (let* ((file-idx (nth 1 (car patterns)))
               (line-idx (nth 2 (car patterns)))
               (col-idx (nth 3 (car patterns)))
               )
          (setq raw-file-name (if file-idx (match-string file-idx line) 
nil))
          (setq line-no       (if line-idx (string-to-number (match-string 
line-idx line)) 0))
          (setq col-no        (if col-idx  (string-to-number (match-string 
col-idx line)) 0))
          (setq err-text      (if (> (length (car patterns)) 4)
                                  (match-string (nth 4 (car patterns)) line)
                                (flymake-patch-err-text (substring line 
(match-end 0)))))
          (or err-text (setq err-text "<no error text>"))
          (if (and err-text (string-match "^[wW]arning" err-text))
              (setq err-type "w")
            )
          (flymake-log 3 "parse line: file-idx=%s line-idx=%s file=%s 
line=%s text=%s" file-idx line-idx
                       raw-file-name line-no err-text)
          (setq matched t)))
      (setq patterns (cdr patterns)))
    (if matched
        ;; cheeso
        ;;(flymake-ler-make-ler raw-file-name line-no err-type err-text)
        (flymake-ler-make-ler raw-file-name line-no err-type err-text nil 
col-no)
      ())))


4 - introduce new fn flymake-er-get-line-col , which returns (LINE COL) for 
the error.

(defun flymake-er-get-line-col (err-info)
  (list (nth 0 err-info)
        (flymake-ler-col-no (car (nth 1 err-info))) ;; xxxx
        ))

5- transform all fns that get line number info, to get line+col info:

(defun flymake-get-first-err-line-col (err-info-list)
  "Return first line with error."
  (when err-info-list
    (flymake-er-get-line-col (car err-info-list))))

(defun flymake-get-last-err-line-col (err-info-list)
  "Return last line with error."
  (when err-info-list
    (flymake-er-get-line-col (nth (1- (length err-info-list)) 
err-info-list))))

(defun flymake-get-next-err-line-col (err-info-list line-no)
  "Return next line with error."
  (when err-info-list
    (let* ((count  (length err-info-list))
           (idx    0))
      (while (and (< idx count) (>= line-no (flymake-er-get-line (nth idx 
err-info-list))))
        (setq idx (1+ idx)))
      (if (< idx count)
          (flymake-er-get-line-col (nth idx err-info-list))))))

(defun flymake-get-prev-err-line-col (err-info-list line-no)
  "Return previous line with error."
  (when err-info-list
    (let* ((count (length err-info-list)))
      (while (and (> count 0) (<= line-no (flymake-er-get-line (nth (1- 
count) err-info-list))))
        (setq count (1- count)))
      (if (> count 0)
          (flymake-er-get-line-col (nth (1- count) err-info-list))))))


6- modify flymake-goto-next-error to use the column information

(defun flymake-goto-next-error ()
  "Go to next error in error ring. Return (LINE COL), or nil if there are no 
errors."
  (interactive)
  (let* ((line-col (flymake-get-next-err-line-col flymake-err-info 
(flymake-current-line-no)))
         (line-no (car line-col))
         (col-no  (cadr line-col))
        )
    (when (not line-no)
      (setq line-col (flymake-get-first-err-line-col flymake-err-info))
      (setq line-no (car line-col)
            col-no  (cadr line-col))
      (flymake-log 1 "passed end of file"))
    (if line-no
        (flymake-goto-line line-col)
      (flymake-log 1 "no errors in current buffer"))))

7- same for flymake-goto-prev-error

(defun flymake-goto-prev-error ()
  "Go to previous error in err ring."
  (interactive)
  (let* ((line-col (flymake-get-prev-err-line-col flymake-err-info 
(flymake-current-line-no)))
         (line-no (car line-col))
         (col-no  (cadr line-col))
        )
    (when (not line-no)
        (setq line-col (flymake-get-last-err-line-col flymake-err-info))
        (setq line-no (car line-col)
              col-no  (cadr line-col))
        (flymake-log 1 "passed beginning of file"))
    (if line-no
        (flymake-goto-line line-col)
      (flymake-log 1 "no errors in current buffer"))))

8- modify flymake-goto-line to accept a (LINE COL) list, and act accordingly

(defun flymake-goto-line (line-col)
  "LINE-COL contains (LINE-NO COL-NO). Go to line LINE-NO, then skip to the 
COL-NO column."
  (let ((line-no (car line-col))
        (col-no (cadr line-col))
        )
    (goto-line line-no)
    (when col-no
      (while (> col-no 1)
        (setq col-no (1- col-no))
        (forward-char))))
  line-col)


-Dino Chiesa
 

bug#8723: 23.2; Flymake should go to error column

[Stefan Kangas]

"D Chiesa" <dpchiesa@hotmail.com> writes:

> Flymake relies on compilation error patterns, similar to
> compilation-error-regexp-alist , to detect errors and warnings.  But
> flymake discards column information for any errors, and as a result,
> the functions flymake-goto-next-error and flymake-goto-prev-error do
> not position the cursor on the error column.

I don't think this is the case these days, after the redesign of flymake
that João did in 2017 or so.  I'm therefore closing this bug report.

If this conclusion is incorrect and this is still an issue, please reply
to this email (use "Reply to all" in your email client) and we can
reopen the bug report.