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I have problems running eval-defun for a defun when there is a square bracket [ in column 0 of its doc string. For example:

(defun test ()
  "Test function. 
[Some text]"
  (message "Hello"))

When I position the cursor inside the function above and type M-x eval-defun RET it displays "[Some text]" in the echo area, but the defun is not being evaluated. If I remove the square bracket [ in the doc string, and then reevaluate, it works fine and displays "test" in the echo area.

I am using GNU Emacs 25.2.1 on Ubuntu 17.04.

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5
  • Seems like a bug to me. Don't have a way to verify this, but what happens if you replace [ with \133?
    – wvxvw
    Oct 20 '17 at 9:02
  • 4
    Just insert a backslash \ before the opening square bracket [. See (emacs) Left Margin Paren.
    – Basil
    Oct 20 '17 at 9:48
  • @Basil Thanks for the link. That seems to be the case, but I wonder why has a bracket in the first column the same effect as a parenthesis for eval-defun? A bracket in the first column cannot be the start of a defun, am I right?
    – Håkon Hægland
    Oct 20 '17 at 9:54
  • 2
    It cannot be the start of a call to the defun macro, but it can be a top-level definition, which is what Emacs documentation refers to as a defun. See (emacs) Defuns. Note also that the documentation is careful to prefer the word "delimiter" to "paren", implying multiple paren-like characters.
    – Basil
    Oct 20 '17 at 10:02
  • What @Basil said. A "defun" in this context is not necessarily a call to Lisp macro defun.
    – Drew
    Oct 20 '17 at 15:29
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AFAIU fixing this would require a hack around of SPECPDL_INDEX in C-source.

However, ar-backward-defun,ar-forward-defun jumps to start and end of a defun also in these cases: https://github.com/andreas-roehler/thingatpt-utils-core/blob/master/ar-subr.el

Wherefrom a command to escape opening parens in column 0 might be provided:

(defun ar-auto-escape ()
  (interactive "*")
  (save-excursion
    (ar-beginning-of-defun)
    (let ((end (save-excursion (ar-end-of-defun) (line-beginning-position))))
      (forward-line 1) 
      (while (and (re-search-forward "^\\([\[(]+\\)" nil t 1) (< (line-beginning-position) end))
    (replace-match (concat "\\\\" (match-string-no-properties 1)))))))
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