Issue #20871 has been updated by jeremyevans0 (Jeremy Evans). Status changed from Open to Feedback The example works as expected on Ruby 3.3.6. It seems unlikely the commit you are referencing is related, because the commits fixes an issue where the method cache is not updated on a change, it wouldn't cause the method not to show up at all. Are you able to provide a self-contained reproducible example for this issue? ---------------------------------------- Bug #20871: Including methods in Enumerable doesn't make them available in Array https://bugs.ruby-lang.org/issues/20871#change-110683 * Author: sanderd17 (Sander Deryckere) * Status: Feedback * ruby -v: 3.3.6 * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Today, our CI pipeline started failing after the automatic update from v3.3.5 to v3.3.6. After researching, it turned out that our core extensions to the `Array` class weren't loaded anymore. The core-extensions code looks like this: ```ruby module CoreExt module Enumerable def average sum(&:to_f) / count if any? end # def ... end end Enumerable.include CoreExt::Enumerable ``` After some debugging, it turned out that the `average` method was included in the `instance_methods` of `Enumerable`, but not in the `instance_methods` of `Array`. Explicitly adding `Array.include CoreExt::Enumerable` fixes CI for our case. The very strange thing is that it only happens on a release branch we are still maintaining. It doesn't happen on our main development branch (which also updated to v3.3.6 today). I have been unable to find the difference between both branches so far (they diverged a couple of months ago, but the base system is still regularly updated on both, and pretty similar). After some digging around, I assume this commit is related to our issue: https://github.com/ruby/ruby/commit/edeb0319f7a95dfe3f9b895bcf32371dd8514726 -- https://bugs.ruby-lang.org/