Bug #17841: The first instance of SortedSet doesn't sort when rbtree is present

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.7.3p183 (2021-04-05 revision 6847ee089d) [x86_64-linux]
• Backport: 2.6: DONTNEED, 2.7: DONE, 3.0: DONTNEED

[joshc (Josh C)]

If the rbtree gem is present, then in ruby 2.7, the first instance of SortedSet will return entries in insertion order. Future instances of SortedSet correctly return sorted entries.

Given:

require 'rbtree'
require 'set'

descending = [2, 1]

s1 = SortedSet.new
descending.each { |i| s1.add(i) }

s2 = SortedSet.new
descending.each { |i| s2.add(i) }

puts s1.to_a == s1.sort.to_a
puts s2.to_a == s2.sort.to_a

It prints:

false
true

It should print:

true
true

The reason for this is because the SortedSet#initialize method monkey patches itself. So the first instance of SortedSet uses the default @hash = {} instead of @hash = RBTree.new, and it doesn't monkey patch the to_a method to sort the hash keys.

This is an issue for anyone adding the sorted_set gem dependency to support both ruby 2 and 3, since the sorted_set gem depends on rbtree

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed
• Backport changed from 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN to 2.6: DONTNEED, 2.7: REQUIRED, 3.0: DONTNEED

This is probably caused by the fix to #15830. Here's a pull request that should fix it: https://github.com/ruby/ruby/pull/4432, though I didn't test with rbtree. Closing and marking for backport.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.6: DONTNEED, 2.7: REQUIRED, 3.0: DONTNEED to 2.6: DONTNEED, 2.7: DONE, 3.0: DONTNEED

merged into ruby_2_7 at 2a7235421fcd59b449c84306d059f22b4c5f0865