bug#33294: xwidget-insert crashes Emacs

[Robert Pluim]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
>> Cc: Robert Pluim <rpluim@gmail.com>, lg.zevlg@gmail.com, gazally@runbox.com,
>>         33294@debbugs.gnu.org
>> Date: Thu, 08 Nov 2018 15:15:50 -0500
>> 
>> > I admit I don't understand why PVEC_XWIDGET and PVEC_XWIDGET_VIEW are
>> > in the "impossible" cases.  They are first-class Lisp objects, AFAICT.
>> 
>> If you say so, then they most likely are, indeed.  I personally didn't
>> (and still don't) know enough about those to know what to do with them.
>
> Can you tell what are the guidelines for putting a PVEC object into
> the "impossible" category in the context of type-of?

They look first class to me as well.

Of the other 'impossible' cases in 'type-of',

- PVEC_MISC_PTR and PVEC_OTHER I think should never be lisp-visible
- PVEC_SUB_CHAR_TABLE is definitely lisp-visible, so for completeness
  we could allow 'type-of' on it
- PVEC_FREE should not be visible, but Iʼm prepared to be wrong about
  that :-)

PVEC_XWIDGET and PVEC_XWIDGET_VIEW are easy enough to handle in
'type-of'. I can do PVEC_SUB_CHAR_TABLE as well if we decide itʼs the
right thing.

Robert