Issue #21029 has been updated by S_H_ (Shun Hiraoka). I've fixed that defined? (x;) returns an expression when using parse.y. https://github.com/ruby/ruby/pull/13821 However, I have a little skeptical about whether this change is a good idea. If any other good suggestions, I would appreciate it if you could comment. ---------------------------------------- Bug #21029: Prism behavior for `defined? (;x)` differs https://bugs.ruby-lang.org/issues/21029#change-113959 * Author: qnighy (Masaki Hara) * Status: Closed * ruby -v: ruby 3.5.0dev (2025-01-11T03:21:57Z master 1b3037081e) +PRISM [x86_64-linux] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Prism has a different behavior for `(;expr)` when used in `defined?` predicate: ```console % ./miniruby --parser=prism -e "p defined? (;x)" nil % ./miniruby --parser=parse.y -e "p defined? (;x)" "expression" ``` Although not a significant difference, aligning either of them with the other would be better. -- https://bugs.ruby-lang.org/