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

[Noam Postavsky]

On Fri, 5 Oct 2018 at 19:02, Paul Eggert <address@hidden> wrote:
>
> On 10/5/18 1:43 AM, Eli Zaretskii wrote:
> > the commonly accepted mechanism of
> > pointing out potentially wrong constructs is by visual cues and
> > warning messages
>
> If we decide that Elisp source code must be able to abuse confusable
> characters, then of course we should allow such abuse and support it as
> best we can, including selective highlighting and whatnot to try to warn
> readers of the abuse. Such support won't work outside Emacs, but people
> using non-Emacs programs to look at Elisp code will simply be out of luck.

The problem is that deciding which characters are confusable and hence
require backslash escaping is based on a shifting mess of heuristics.
So I don't think it's workable to signal a hard error for this. Both
in terms of false positives which could mean possibly breaking code,
and false negatives which means we would be giving a false sense of
security. That's why I proposed adding highlighting and enhancing
existing error messages instead. Of course adding warnings would also
make sense.

By the way, your EN SPACE example already gives a compile warning:

Warning: Unused lexical variable ‘data data’