Issue #19533 has been updated by matz (Yukihiro Matsumoto). It is an unintentional behavior. I agree to fix `nil .. nil` case. Matz. ---------------------------------------- Bug #19533: Behavior of ===/include? on a beginless/endless range (nil..nil) changed in ruby 3.2 https://bugs.ruby-lang.org/issues/19533#change-102757 * Author: knu (Akinori MUSHA) * Status: Open * Priority: Normal * Target version: 3.2 * ruby -v: ruby 3.2.1 (2023-02-08 revision 31819e82c8) [x86_64-darwin22] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- Starting from Ruby 2.7.0 a range `nil..nil` used to match any value until 3.2.0-preview3, but 3.2.0-rc1 started to reject it. ``` % docker run -it --rm rubylang/all-ruby ./all-ruby -e 'p( (nil..nil) === 1 )' (snip) ruby-2.6.10 false ruby-2.7.0-preview1 true ... ruby-3.2.0-preview3 true ruby-3.2.0-rc1 -e:1:in `===': cannot determine inclusion in beginless/endless ranges (TypeError) p( (nil..nil) === 1 ) ^ from -e:1:in `<main>' exit 1 ... ruby-3.2.1 -e:1:in `===': cannot determine inclusion in beginless/endless ranges (TypeError) p( (nil..nil) === 1 ) ^ from -e:1:in `<main>' ``` The previous behavior was so useful because when you have optional lower and upper bounds `lbound..rbound` would always work regardless of each end being nil or not. There is no mention of this in doc/NEWS/NEWS-3.2.0.md, so I'm afraid it was caused unintentionally while fixing other problems. ``` % docker run -it --rm rubylang/all-ruby ./all-ruby -e 'p( (nil..nil).cover?(1) )' (snip) ruby-2.6.10 false ruby-2.7.0-preview1 true ... ruby-3.2.1 true ``` This was pointed out by the following blog article (written in Japanese) as a "pitfall" that you need to work around when upgrading Ruby from 3.0/3.1 to 3.2. https://blog.studysapuri.jp/entry/2023/03/16/ujihisa-ruby32#endless-range%E3... -- https://bugs.ruby-lang.org/