regexp: simple Ruby regular expression doesn’t work

[gopherbot]

by blake.mizerany:

I’ve been slowly working on migrating more of Heroku’s codebase over to Go. One of
my more Ruby-centric coworkers just wasted several hours today on Go’s lack of support
for this regular expression:

    var validRequest = regexp.MustCompile(`^/customer/(\w+)/(\w+)?authas=\1(&.*)?`)

After tweaking, I’ve narrowed it down to this minimal repro case:

   var r = regexp.MustCompile(`^(a).+\1`)

That works fine in Ruby:

$ irb
>> "abba".match(/^(a).+\1/)
=> #<MatchData "abba" 1:"a">

Why doesn’t this work in Go?

Not to look a gift horse in the mouth, but I’ll have a harder time getting co-workers
to adopt Go if such basic things from Ruby aren’t even supported.

[bradfitz]

Comment 1:

Sorry!  Here's a fix: http://golang.org/cl/5971058/

[dsymonds]

Comment 2:

This is a little embarrassing, for sure. How can people take Go seriously?

Labels changed: added priority-asap, packagebug, expertneeded, performance, removed priority-triage.

Owner changed to @bradfitz.

Status changed to Started.

[rsc]

Comment 3:

Status changed to Fixed.

[bradfitz]

Comment 4:

I promised Blaked to update this bug, for the record, that he is not an idiot, and will
not be banned from the Go community.
Thanks for playing along, Blake!

Labels changed: added aprilfools.

[cznic]

Comment 5:

;-)