GNU bug report logs - #54488
29.0.50; move-to-column/overlay-related regression in latest master, perhaps 28?

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Message #47 received at 54488 <at> debbugs.gnu.org (full text, mbox):

From: João Távora <joaotavora <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 54488 <at> debbugs.gnu.org, Dmitry Gutov <dgutov <at> yandex.ru>
Subject: Re: bug#54488: 29.0.50; move-to-column/overlay-related regression in
 latest master, perhaps 28?
Date: Tue, 22 Mar 2022 16:06:48 +0000

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On Tue, Mar 22, 2022 at 3:22 PM Eli Zaretskii <eliz <at> gnu.org> wrote:

> > From: João Távora <joaotavora <at> gmail.com>
> > Cc: dgutov <at> yandex.ru,  54488 <at> debbugs.gnu.org
> > Date: Tue, 22 Mar 2022 14:54:13 +0000
> >
> > In Emacs 29, before the fix, that (point) seems to -- very surprisingly
> > -- return something beyond the narrowed region and so
> > encode-coding-string will complain with args out of range.
>
> I don't understand how (point) can return a value outside of the
> narrowed region, unless it runs with the narrowing temporarily
> disabled.  Can you show me the code with that call to 'point' again?
> I don't think I see it in your OP.
>

It's the snippet below. but the indentation probably botched it.
I inlined a function in that snippet so you can see the move-to-column
and the (point) in the same function (normally they live in different
functions).

> (defun eglot-move-to-lsp-abiding-column (column)
> >   "Move to COLUMN abiding by the LSP spec."
> >   (save-restriction
> >     (cl-loop
> >      with lbp = (line-beginning-position)
> >      initially
> >      (narrow-to-region lbp (line-end-position))
> >      (move-to-column column)
> >      for diff = (- column
> >                    (/ (- (length (encode-coding-region (or lbp
> (line-beginning-position))
> >                                         (point) 'utf-16 t))   ;; <=====
> THAT (point)
> >                                   2)
> >                        2))
> >      until (zerop diff)
> >      do (condition-case eob-err
> >             (forward-char (/ (if (> diff 0) (1+ diff) (1- diff)) 2))
> >           (end-of-buffer (cl-return eob-err))))))
>
> Why do you have to use move-to-column instead of forward-char?
>

I don't remember! Is it exactly equivalent if you're standing in the
beginning of the line?

João


-- 
João Távora

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