From: Nobuyoshi Nakada <nobu@...>
Date: 2008-02-20T21:59:37+09:00
Subject: Re: possible bug in regexp lexing

Hi,

At Tue, 19 Feb 2008 16:11:37 +0900,
Tanaka Akira wrote in [ruby-core:15602]:
> > % ./miniruby -ve 'p %r{\}}' 
> > ruby 1.8.6 (2008-02-05 patchlevel 5000) [i686-linux]
> > -e:1: warning: regexp has `}' without escape
> > /}/
> 
> More problems:
> 
> % ./miniruby -e 'p %r(\))'
> -e:1: unmatched ): /)/
> % ./miniruby -e 'p %r|\|| =~ "a"'
> 0
> % ./miniruby -e 'p %r?\??'
> -e:1: invalid regular expression; there's no previous pattern, to which '?' would define cardinality at 1: /?/

I think it ambiguous, whether it means an escaped terminator or
an escaped meta character, and unsafe.  We should define the
expected behavior for such cases first.

-- 
Nobu Nakada