Re: Unicode confusables and reordering characters considered harmful

[Andreas Schwab]

On Nov 03 2021, Gregory Heytings wrote:

> diff --git a/lisp/progmodes/prog-mode.el b/lisp/progmodes/prog-mode.el
> index db350a5f70..0005d3d4d7 100644
> --- a/lisp/progmodes/prog-mode.el
> +++ b/lisp/progmodes/prog-mode.el
> @@ -289,6 +289,24 @@ turn-on-prettify-symbols-mode
>               (local-variable-p 'prettify-symbols-alist))
>      (prettify-symbols-mode 1)))
>  
> +(defun fontify-bidi-reordering-characters ()
> +  (font-lock-add-keywords nil '(("⁩\\|‬\\|⁨\\|⁧\\|⁦\\|‫\\|‪\\|‮\\|‭" . 
> 'font-lock-warning-face))))
> +
> +(defun make-bidi-reordering-characters-visible ()
> +  (setq buffer-display-table (or buffer-display-table
> +                                 standard-display-table
> +                                 (make-display-table)))
> +  (aset buffer-display-table ?‪ [?→])
> +  (aset buffer-display-table ?‫ [?←])
> +  (aset buffer-display-table ?‭ [?→])
> +  (aset buffer-display-table ?‮ [?←])
> +  (aset buffer-display-table ?⁦ [?→])
> +  (aset buffer-display-table ?⁧ [?←])
> +  (aset buffer-display-table ?⁨ [?↓])
> +  (aset buffer-display-table ?‬ [?↑])
> +  (aset buffer-display-table ?⁩ [?↑])

A perfect example of how legitimate use of these characters can mess up
your source. :-)

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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