bug#5757: String literal parse problem in ruby-mode

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Could you help review Pål de Vibe's proposed fix to the following
> problem in Emacs ruby-mode?  Thanks.

His proposed fix is not correct: in ruby (like in Elisp) ?<char> is used
for chars (including ?' and ?") and $' and $" are also special vars, so
his fix just disables the special treatment of ?.
For Emacs-24, we use a different chunk of code which doesn't suffer from
this problem (mostly calling syntax-ppss to determine if we're inside
a string).


        Stefan


> Pål de Vibe <pauldevibe@yahoo.no> writes:

>>> ruby-mode will misunderstand a ruby double-quoted string literal which
>>> contains a single quote and ends with a question mark.  It thinks that
>>> the string literal is unterminated, which contaminates the syntax
>>> highlighting for the remainder of the buffer.
>>> 
>>> Example ruby code which will demonstrate the problem:
>>> 
>>> ["Is 'this' a string?"], [:something, :else]
>>> 
>>> If there's anything between the question mark and the terminating
>>> double-quote, the string will be correctly interpreted.
>> 
>> Line 1185:
>> ("\\(^\\|[^\\\\]\\)\\(\\\\\\\\\\)*[?$]\\([#\"'`]\\)" 3 (1 . nil))
>> 
>> A workaround (with, to me, uknown consequences) is to remove the
>> question mark from the line, like this:
>> 
>> ("\\(^\\|[^\\\\]\\)\\(\\\\\\\\\\)*[$]\\([#\"'`]\\)" 3 (1 . nil))