Issue #19113 has been updated by matz (Yukihiro Matsumoto). I agree with @jeremyevans0 too. Matz. ---------------------------------------- Bug #19113: Inconsistency in retention of compare_by_identity flag in Hash methods https://bugs.ruby-lang.org/issues/19113#change-100764 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Priority: Normal * ruby -v: ruby 3.2.0dev (2022-11-07T17:29:28Z master 9001e53e68) [x86_64-openbsd7.2] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- `Hash.[]` and `Hash.ruby2_keywords_hash` retain the compare_by_identity flag for non-empty hashes, but do not retain it for empty hashes: ```ruby hs = [{}.compare_by_identity, {:a=>1}.compare_by_identity] hs.map{|h| Hash[h].compare_by_identity?} # => [false, true] hs.map{|h| Hash.ruby2_keywords_hash(h).compare_by_identity?} # => [false, true] ``` This inconsistency seems like a bug. `Hash#compact` always drops the compare_by_identity flag, but it is documented as returning a copy of self, implying the compare_by_identity flag is kept (since #dup and #clone retain the flag). ```ruby {}.compare_by_identity.compact.compare_by_identity? # => false ``` I'm not sure whether is a bug, because it is consistent, but I think retaining the flag makes more sense. I'll try to work on a fix for both of these issues tomorrow. -- https://bugs.ruby-lang.org/