Re: Bug: org-string-display throws on image display property [9.1.9 (release_9.1.9-65-g5e4542 @ /home/blc/.local/share/emacs/27.0.50/lisp/org/)]

[Nicolas Goaziou <mail@nicolasgoaziou.fr>]

Hello,

"Basil L. Contovounesios" <contovob@tcd.ie> writes:

> Severity: minor
>
> 0. emacs -Q
> 1. M-x toggle-debug-on-error RET
> 2. Evaluate the following:
>
>   (require 'org)
>   (org-string-display
>    (propertize " " 'display '(image :type svg
>                                     :file "/path/to/image.svg")))
>
> This gives the following error backtrace:
>
> Debugger entered--Lisp error: (wrong-type-argument sequencep t)

`org-string-display' doesn't exist anymore in master (Org 9.2). However,
there is the same error with `org-string-width'. 

What is `org-string-width' supposed to do on your example? Probably
return an error.

> I realise that org-string-display is a relatively obscure function that
> was probably not designed with image or other complex display properties
> in mind, but AFAICT the following is a pretty obvious "fix", given that
> the surrounding code expects 'value' to be a string or nil, but never t:
>
> diff --git a/lisp/org/org-macs.el b/lisp/org/org-macs.el
> index 583633605f..5ab069e6a2 100644
> --- a/lisp/org/org-macs.el
> +++ b/lisp/org/org-macs.el
> @@ -108,7 +108,7 @@ org-string-display
>  		       ;; string (face...).
>  		       (let* ((display (plist-get props 'display))
>  			      (value (if (stringp display) display
> -				       (cl-some #'stringp display))))
> +                                       (cl-find-if #'stringp display))))
>  			 (when value
>  			   (apply #'propertize
>  				  ;; Displayed string could contain
>
>
> With this change, the return value of org-string-display does not really
> make sense for images, but at least the function doesn't barf on complex
> but valid display properties.  WDYT?

If `org-string-width' returns nil, it will ensue an error somewhere
further in the code. So returning an error right here is better (or
find a way to compute the width of an image in columns).

As another data point, `string-width' returns 1 on your example, which
is probably wrong.

WDYT?

Regards,

-- 
Nicolas Goaziou