Issue #20223 has been reported by mjflynt (Jeffrey Flynt). ---------------------------------------- Bug #20223: For simple objects each_cons appears to work as I expect, but for other objects it seems to fail to terminate iterations when I would expect. https://bugs.ruby-lang.org/issues/20223 * Author: mjflynt (Jeffrey Flynt) * Status: Open * Priority: Normal * ruby -v: ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [aarch64-linux] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Reproduce process: ``` ruby p `ruby -v` class X include Enumerable attr_accessor :obj def initialize = @obj = (1..5).to_a def each(&block) = yield @obj.each(&block) end wtf = X.new (1..5).each_cons(3) { |g| p g } p '~' * 20 (1..5).to_a.each_cons(3) { |g| p g } p '~' * 20 ('a'..'e').each_cons(3) { |g| p g } p '~' * 20 wtf.each_cons(3) { |g| p g } ``` Result of reproduce process ``` "ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [aarch64-linux]\n" [1, 2, 3] [2, 3, 4] [3, 4, 5] "~~~~~~~~~~~~~~~~~~~~" [1, 2, 3] [2, 3, 4] [3, 4, 5] "~~~~~~~~~~~~~~~~~~~~" ["a", "b", "c"] ["b", "c", "d"] ["c", "d", "e"] "~~~~~~~~~~~~~~~~~~~~" [1, 2, 3] [2, 3, 4] [3, 4, 5] [4, 5, [1, 2, 3, 4, 5]] [Done] exited with code=0 in 0.173 seconds ``` Expected result and the reason why you expect I expect the results to not include the last line of output "[4, 5, [1, 2, 3, 4, 5]]" because my understanding is each_cons ends its iteration over the collection before it runs out of elements. In this case, this fourth row does not have enough elements to do three consecutive elements, but it is doing so anyway, appearing to use the original array as the third element before it completes. -- https://bugs.ruby-lang.org/