Issue #20930 has been updated by Eregon (Benoit Daloze). 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) ``` Which is still inconsistent between `it` and `_1`. ---------------------------------------- Bug #20930: Different semantics for nested `it` and `_1` https://bugs.ruby-lang.org/issues/20930#change-110852 * 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 ---------------------------------------- ``` $ 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) ``` --- 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 ``` -- https://bugs.ruby-lang.org/