Issue #20930 has been updated by mame (Yusuke Endoh). Discussed at the dev meeting, and matz confirmed that the current master's behavior is good. ---------------------------------------- Bug #20930: Different semantics for nested `it` and `_1` https://bugs.ruby-lang.org/issues/20930#change-110970 * Author: Eregon (Benoit Daloze) * Status: Open * ruby -v: ruby 3.4.0dev (2024-12-04T19:29:24Z master 3c91a1e5fd) +PRISM [x86_64-linux] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- With --parser=parse.y: ``` $ ruby --parser=parse.y -ve '[1].each { p it; [5].each { p it } }' ruby 3.4.0dev (2024-12-04T19:29:24Z master 3c91a1e5fd) [x86_64-linux] 1 5 $ ruby --parser=parse.y -ve '[1].each { p _1; [5].each { p _1 } }' ruby 3.4.0dev (2024-12-04T19:29:24Z master 3c91a1e5fd) [x86_64-linux] -e:1: numbered parameter is already used in -e:1: outer block here [1].each { p _1; [5].each { p _1 } } ruby: compile error (SyntaxError) ``` The behavior is inconsistent between it and _1. --- <details> <summary>Side note about mixing `_1` and `it`, which seems good</summary> As an aside, mixing `_1` and `it` is allowed, I think this is [good](https://bsky.app/profile/eregon.bsky.social/post/3lcg4fjcf7225), they are different things so there is not much confusion there: ``` $ ruby -ve '[1].each { p _1; [5].each { p it } }' ruby 3.4.0dev (2024-12-04T19:29:24Z master 3c91a1e5fd) +PRISM [x86_64-linux] 1 5 $ ruby -ve '[1].each { p it; [5].each { p _1 } }' ruby 3.4.0dev (2024-12-04T19:29:24Z master 3c91a1e5fd) +PRISM [x86_64-linux] 1 5 ``` </details> --- <details> <summary>Prism's bug, moved to: https://github.com/ruby/prism/issues/3291</summary> ``` $ ruby -ve '[1].each { p it; [5].each { p it } }' ruby 3.4.0dev (2024-12-04T19:29:24Z master 3c91a1e5fd) +PRISM [x86_64-linux] 1 5 $ ruby -ve '[1].each { p _1; [5].each { p _1 } }' ruby 3.4.0dev (2024-12-04T19:29:24Z master 3c91a1e5fd) +PRISM [x86_64-linux] 1 1 ``` Notice the inconsistency, `it` uses the innermost block, `_1` uses the outermost block. I think `_1` semantics are slightly better, at least `_1` behaves like a normal local variable declared in the outer block then. Note that on 3.3.5 it was forbidden to nest `_1` which I think might be good for clarity/avoiding ambiguity: ``` $ ruby -ve '[1].each { p _1; [5].each { p _1 } }' ruby 3.3.5 (2024-09-03 revision ef084cc8f4) [x86_64-linux] -e:1: numbered parameter is already used in -e:1: outer block here [1].each { p _1; [5].each { p _1 } } ruby: compile error (SyntaxError) ``` </details> -- https://bugs.ruby-lang.org/