Issue #7298 has been updated by marcandre (Marc-Andre Lafortune). Status changed from Assigned to Closed Sorry, completely forgot to check rubyspec. Fixed. I'll take this occasion to open a new feature request sitting on my todo list for over a year... ---------------------------------------- Bug #7298: Behavior of Enumerator.new different between 1.9.3 and 2.0.0 https://bugs.ruby-lang.org/issues/7298#change-32537 Author: ayumin (Ayumu AIZAWA) Status: Closed Priority: Normal Assignee: marcandre (Marc-Andre Lafortune) Category: Target version: 2.0.0 ruby -v: ruby 2.0.0dev (2012-11-07 trunk 37528) [x86_64-darwin12.2.0] Under 1.9.3, when Enumerator.new was called with arguments and block, it return Enumerator object. But under trunk, it makes TypeError. $ ruby -v -e "p Enumerator.new([1,2,3]){|y|y.yield 4}" ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin11.4.2] #<Enumerator: [1, 2, 3]:each> $ ./ruby -v -e "p Enumerator.new([1,2,3]){|y|y.yield 4}" ruby 2.0.0dev (2012-11-07 trunk 37528) [x86_64-darwin12.2.0] -e:1:in `initialize': can't convert Array into Integer (TypeError) from -e:1:in `new' from -e:1:in `<main>' -- http://bugs.ruby-lang.org/