Subject: Re: bug#56773: 29.0.50; (readablep UNREADABLE) causes strange things

From: Po Lu <[email-masked]>
Date: Wed, 27 Jul 2022 17:41:12 +0800

Lars Ingebrigtsen <[email-masked]> writes:

> Eli Zaretskii <[email-masked]> writes:
>
>> unwind_protect?
>
> Where would the unwind_protect be?
>
> The problem is here:
>
>   if (!NILP (Vprint_unreadable_function)
>       && FUNCTIONP (Vprint_unreadable_function))
>     {
>       specpdl_ref count = SPECPDL_INDEX ();
>       /* Bind `print-unreadable-function' to nil to avoid accidental
> 	 infinite recursion in the function called.  */
>       Lisp_Object func = Vprint_unreadable_function;
>       specbind (Qprint_unreadable_function, Qnil);
>       Lisp_Object result = CALLN (Ffuncall, func, obj,
> 				  escapeflag? Qt: Qnil);
>
> We need to switch back to the original buffer before that Ffuncall, but
> we don't know what the original function was -- it's just stored in a
> local variable in prin1(-to-string).

Isn't that problem already present?  IOW, that function is still called
in the internal buffer under the current code.