> On 13 Jan 2015, at 22:23, Allen Wirfs-Brock <allen at wirfs-brock.com> wrote:
> 
> Would those of you who consider yourselves RegExp experts take a look at https://bugs.ecmascript.org/show_bug.cgi?id=3519  Is this a bug? If so, what is the fix?
> 
> This construction for Identity Escape goes back to Norbert's original proposal http://norbertlindenberg.com/2012/05/ecmascript-supplementary-characters/index.html 
> 
> Perhaps we need to add a:
>   ClassAttom[U] :: [+U]  \-
> 
> production or some such to the pattern grammar.

I think it’s a bug — see https://codereview.chromium.org/788043005/diff/220001/src/parser.cc#newcode4354 for the discussion that led to this report.

Your change would allow developers to use an escaped `-` in a character class, e.g. `/[a-f\-A-Z]/u`, rather than having to move it to the beginning (i.e. `/[-a-fA-Z]/u` or end (`/[a-fA-Z-]/u`) of the character class, as is possible today without the `u` flag. That is a good thing IMHO.

I think it’s a bug — see https://codereview.chromium.org/788043005/diff/220001/src/parser.cc#newcode4354 for the discussion that led to this report.

Your change would allow developers to use an escaped `-` in a character class, e.g. `/[a-f\-A-Z]/u`, rather than having to move it to the beginning (i.e. `/[-a-fA-Z]/u` or end (`/[a-fA-Z-]/u`) of the character class, as is possible today without the `u` flag. That is a good thing IMHO.