Subject: Re: bug#24542: 25.1.50; The symbol `@' and sexp scanning

From: [email-masked]
Date: Tue, 03 Jan 2017 08:03:54 -0500

Michael Heerdegen <[email-masked]> writes:
>> `@' has the prefix syntax flag, the elisp manual says `(elisp) Syntax Flags':
>>
>>    * `p' identifies an additional prefix character for Lisp syntax.
>>      These characters are treated as whitespace when they appear between
>>                           ^^^^^^^^^^^^^^^^^^^^^
>>      expressions.  When they appear within an expression, they are
>>      handled according to their usual syntax classes.
>>
>> So (eq element '@) acts the same as (eq element ' ).
>
> I don't agree with your interpretation.  `@' is an (textual
> representation of an) expression in the above example, so "these
> characters" don't "appear between expressions" in this case.  Could be
> that this wording led to a wrong implementation, however.

Well, it's a bit ambiguous whether a character sequence composed soley
of prefix characters should be considered an expression or not.
Obviously the end result is wrong for Lisp, i.e., does not correspond
with what `read' thinks.