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bug#4030: forward-sexp parses character literal ?; as comment
From: |
Andrew Hyatt |
Subject: |
bug#4030: forward-sexp parses character literal ?; as comment |
Date: |
Fri, 17 Jun 2016 23:47:07 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (darwin) |
This problem still exists in Emacs 25, and this was the last message in
the thread.
When I try this, though, I do at least see the issue pretty clearly due
to font-locking.
Does anyone have any further thoughts? It wasn't clear to me from this
discussion whether there was any consensus that this was actually a bug
or not.
martin rudalics <rudalics@gmx.at> writes:
>> Yes, but we need to do that even on chunks of code that have not yet
>> been (and may never be) displayed and in buffers where font-lock
>> is disabled. IOW I'm not talking about fontification but about parsing.
>
> Sure. But I was only talking about the possibility to highlight such
> instances just like we do with column 0 parens in strings already.
>
>> Pretty much, yes, tho the error message should give more info (the OP
>> complained about lack of info in the error message).
>
> That's what the ellipsis stands for. But what info? Guessing a good
> buffer position seems next to impossible. Where else can `forward-sexp'
> go astray when called from a top-level position?
>
>>> But do we really have to scan the buffer in the first place?
>>
>> Don't know. Maybe not, indeed. Maybe it's just to detect the "too many
>> closing parens" case as well (i.e. rather than silently ignore trailing
>> code).
>
> We could simply search for (concat "^(" (symbol-name symbol))) and do a
> `forward-sexp' over the form starting there as in the attached patch. I
> see no reason why we should try to handle an .emacs broken before or
> after that form.
>
> martin
>
> *** cus-edit.el.~1.364.~ 2009-07-27 08:09:05.997162900 +0200
> --- cus-edit.el 2009-08-11 10:51:21.812500000 +0200
> ***************
> *** 4338,4374 ****
>
> This function does not save the buffer."
> (goto-char (point-min))
> ! ;; Skip all whitespace and comments.
> ! (while (forward-comment 1))
> ! (or (eobp)
> ! (save-excursion (forward-sexp (buffer-size)))) ; Test for scan errors.
> ! (let (first)
> ! (catch 'found
> ! (while t ;; We exit this loop only via throw.
> ! ;; Skip all whitespace and comments.
> ! (while (forward-comment 1))
> ! (let ((start (point))
> ! (sexp (condition-case nil
> ! (read (current-buffer))
> ! (end-of-file (throw 'found nil)))))
> ! (when (and (listp sexp)
> ! (eq (car sexp) symbol))
> ! (delete-region start (point))
> ! (unless first
> ! (setq first (point)))))))
> ! (if first
> ! (goto-char first)
> ! ;; Move in front of local variables, otherwise long Custom
> ! ;; entries would make them ineffective.
> ! (let ((pos (point-max))
> ! (case-fold-search t))
> ! (save-excursion
> ! (goto-char (point-max))
> ! (search-backward "\n\^L" (max (- (point-max) 3000) (point-min))
> ! 'move)
> ! (when (search-forward "Local Variables:" nil t)
> ! (setq pos (line-beginning-position))))
> ! (goto-char pos)))))
>
> (defun custom-save-variables ()
> "Save all customized variables in `custom-file'."
> --- 4338,4364 ----
>
> This function does not save the buffer."
> (goto-char (point-min))
> ! (if (re-search-forward (concat "^(" (symbol-name symbol)))
> ! (let ((from (goto-char (match-beginning 0)))
> ! (to (condition-case nil
> ! (progn
> ! (forward-sexp)
> ! (point))
> ! (error nil))))
> ! (if to
> ! (delete-region from to)
> ! (error "Malformed %s expression" symbol)))
> ! ;; Move in front of local variables, otherwise long Custom
> ! ;; entries would make them ineffective.
> ! (let ((pos (point-max))
> ! (case-fold-search t))
> ! (save-excursion
> ! (goto-char (point-max))
> ! (search-backward "\n\^L" (max (- (point-max) 3000) (point-min))
> ! 'move)
> ! (when (search-forward "Local Variables:" nil t)
> ! (setq pos (line-beginning-position))))
> ! (goto-char pos))))
>
> (defun custom-save-variables ()
> "Save all customized variables in `custom-file'."
- bug#4030: forward-sexp parses character literal ?; as comment,
Andrew Hyatt <=