bug#15874: 24.3.50; exit! not properly font-locked in ruby-mode

[Dmitry Gutov]

Kevin Rodgers <kevin.d.rodgers@gmail.com> writes:

>> Any ideas for a regexp that matches (any) non-symbol character?
>
> `\sCODE'
> `\SCODE'

That doesn't really help, unless we want to enumerate all syntax classes
that we can accept.

Non-symbol character is a character that's not of class "symbol", nor of
class "word". "\\S_" matches words.