Issue #19833 has been reported by ksss (Yuki Kurihara). ---------------------------------------- Bug #19833: Superclass of BasicObject is broken. https://bugs.ruby-lang.org/issues/19833 * Author: ksss (Yuki Kurihara) * Status: Open * Priority: Normal * ruby -v: ruby 3.3.0dev (2023-08-08T00:21:45Z master 69292676a2) [arm64-darwin22] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- I encountered a phenomenon where a non-class object appeared in the superclass of BasicObject. The minimum reproduction code is below. ```rb module Mod end BasicObject.include Mod # or BasicObject.prepend Mod p BasicObject.superclass #=> 2431129 or false ``` I think it is a practical problem because I found it by running code that monitors `singleton_method_added` as follows. https://github.com/ksss/orthoses/blob/341019c78ba625bc5d36c0f359c7d88621990f... -- https://bugs.ruby-lang.org/