bug#42904: [PATCH] Non-Unicode frame title crashes Emacs on macOS

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Thu, 20 Aug 2020 11:27:01 +0200
> Cc: Eli Zaretskii <eliz@gnu.org>, 42904@debbugs.gnu.org
> 
> There is a minor imperfection: the incoming name string can actually be 
> miscoded if it contains both non-ASCII characters and raw bytes. As an 
> example, consider
> 
>  (rename-buffer "aéb\300")
> 
> In xdisp.c:12497, the Lisp name string is created using make_string which 
> decides that the above multibyte string should really be unibyte, and that 
> confuses the converter. It is of no great consequence, but it makes the 
> result look messier than it should have: "a��b��c" instead of "aéb�c".

What would you like xdisp.c to do instead in this case?  If there's an
alternative way of dealing with such frame titles that is better in
some sense, we could either adopt it for all platforms, or only for
NS.