Issue #20307 has been updated by byroot (Jean Boussier). ignore me, I misunderstood the reproduction script. `h` is not compared by identity. ---------------------------------------- Bug #20307: `Hash#update` from compare_by_identity hash can have unfrozen string keys https://bugs.ruby-lang.org/issues/20307#change-107116 * Author: nobu (Nobuyoshi Nakada) * Status: Open * Backport: 3.0: REQUIRED, 3.1: REQUIRED, 3.2: REQUIRED, 3.3: REQUIRED ---------------------------------------- I don't think this behavior is expected. ```ruby i = Hash.new.compare_by_identity k = "a" i[k] = 0 h = {}.update(i) p h.compare_by_identity? # => false p h["a"] # => 0 k.upcase! # `k` is still in `h`. p h.keys.include?(k) # => true # but not found. p((h.fetch(k) rescue $!)) # => #<KeyError: key not found: "A"> h["A"] = 1 p h # => {"A"=>0, "A"=>1} ``` I expect `h` to still have `"a"=>0` entry. -- https://bugs.ruby-lang.org/