Re: Change of Lisp syntax for "fancy" quotes in Emacs 27?

[Eli Zaretskii <eliz@gnu.org>]

> Cc: Eli Zaretskii <eliz@gnu.org>, Emacs developers <emacs-devel@gnu.org>,
>  Drew Adams <drew.adams@oracle.com>
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Tue, 9 Oct 2018 08:30:22 -0700
> 
> Noam Postavsky wrote:
> > deciding which characters are confusable and hence
> > require backslash escaping is based on a shifting mess of heuristics.
> 
> No more than the "shifting mess of heuristics" inevitable in any choice of 
> syntax. Quite possibly the confusables list from the Unicode consortium will do. 
> The list won't shift much once it's established.
> 
> We can start merely by warning about confusable characters and seeing how often 
> those warnings are triggered in real (as opposed to malicious or 
> purposely-tricky) code. If the warnings are quite rare, in a later Emacs version 
> we can change the manual from "confusable characters should be escaped" to 
> "confusable characters must be escaped".

Confusable characters are confusable only when they are surrounded by
ASCII characters or by characters that look like ASCII.  By
themselves, at least many of them, are entirely legitimate.  For
example, I see no reason to warn about a symbol named "сталин", even
though the characters с and а will be considered confusables if the
symbol would be named something like "саn".

So I think we cannot go by characters here, we need to examine the
context.

That is why I think we shouldn't link this particular issue, of quote
characters, with the more general problem: the latter is much more
complicated to solve correctly.