Issue #22264 has been updated by jeremyevans0 (Jeremy Evans). I'm not sure whether it is desirable to warn for `{a: 1, **{a: 2}}`. I would guess that internally, this hits the same warning for `{a: 1, a: 2}` (which should warn), but for implementation details, it doesn't hit the warning for `{**{}, a: 1, **{a: 2}}`. I think we should only warn for keywords in the same hash, not keywords in a splatted hash, even if the splatted hash is a literal. For one, warnings are to help Ruby programmers, and `{a: 1, **{a: 2}}` is not something a typical Ruby programmer would write (while `{a: 1, a: 2}` is a fairly common mistake). There is no reason for a Ruby programmer to deliberately keyword splat a literal hash inside a another hash. ---------------------------------------- Bug #22264: Warning missing from parse.y hash literals https://bugs.ruby-lang.org/issues/22264#change-118659 * Author: kddnewton (Kevin Newton) * Status: Open * Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- $ ruby --parser=parse.y -cve '{**{}, a: 1, **{a: 2}}' ruby 4.1.0dev (2026-04-21T02:07:14Z aot be86d5704f) [arm64-darwin23] Syntax OK $ ruby --parser=parse.y -cve '{a: 1, **{a: 2}}' ruby 4.1.0dev (2026-04-21T02:07:14Z aot be86d5704f) [arm64-darwin23] -e:1: warning: key :a is duplicated and overwritten on line 1 Syntax OK -- https://bugs.ruby-lang.org/