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

[Paul Eggert <eggert@cs.ucla.edu>]

On 02/02/2018 02:24 PM, Noam Postavsky wrote:
> In Bug#30217, Drew Adams strongly objects to this change. I don't want
> to "sneak" this in, so I'm asking here for people's thoughts on this.

I see two main categories of users here, with different needs. 
Less-expert users are likely to run into problems with quotes and other 
characters (that's why we got bug reports), and appreciate diagnostics 
pinpointing the problems; also, programmers concerned about security are 
likely to want these confusing characters to be diagnosed, to prevent an 
attacker from sending code that is easily read one way but actually 
operates in a different way. On the other hand, programs that generate 
Elisp code might prefer not having to special-case these characters. So 
perhaps there should be a buffer-local variable that controls which 
behavior is selected. The default behavior should be the one that caters 
better to general users and is safer.

While we're on the topic, I suggest using the Unicode confusables list 
<http://www.unicode.org/Public/security/10.0.0/confusables.txt> to come 
up with a list of confusing alternatives for each character that has a 
special meaning in Emacs Lisp. This should be better than our trying to 
come up with our own, ad-hoc list. For example, U+A78C LATIN SMALL 
LETTER SALTILLO (ꞌ) looks almost exactly like an apostrophe on my screen 
and is in the confusables list, but is not a character that Emacs 
currently checks for.