bug#45428: 27.1; (quote (quote (quote ...))) unexpectedly works as anonymous face

[Eli Zaretskii]

> From: Markus Triska <triska@metalevel.at>
> Cc: Drew Adams <drew.adams@oracle.com>,  larsi@gnus.org,  stefan@marxist.se,  
> 45428@debbugs.gnu.org
> Date: Tue, 29 Dec 2020 17:40:38 +0100
> 
> In the original bug report, the property value has the form:
> 
>     (quote (quote (quote ...)))
> 
> I recognize that it is a list. However, I do not recognize that each of
> its elements is given "by any of the above forms", i.e., by any of:
> 
> >   . a face symbol
> >   . a property list of attribute/value pairs
> >   . a cons cell of the form (foreground-color . COLOR)
> >   . a cons cell of the form (background-color . COLOR)
> 
> Could you please clarify which of these forms match (quote (quote ...)) ?

It's a list, obviously.  And the face specification as a list can be
recursive, because it can be a list of any mix of any of the allowed
forms, including a list.