Bug #21030: Bug: #step with Range<ActiveSupport::Duration> behavior broken on Ruby 3.4.1

• Status: Closed
• Assignee: zverok (Victor Shepelev)
• Target version: -
• Backport: 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: REQUIRED

[johnnyshields (Johnny Shields)]

Issue also filed at: https://github.com/rails/rails/issues/54199

System configuration

Rails version: 7.1.5.1
Ruby version: 3.3.4 (works) vs 3.4.1 (broken)

What's broken

Calling #step then #to_a on a Range whose beginning/end values are the same is expected to return an Array wrapping the Range's singular value. In other words, (x..x).step(n).to_a should return [x] -- note this is also the same as (x..x).to_a

The following case breaks on Ruby 3.4.1 related to ActiveSupport::Duration class, where it returns an empty array. It works on Ruby 3.3. Both tested with Rails 7.1.5.1. It's very easy to reproduce.

I'm unsure if this is a Ruby bug or a Rails bug so I'm filing it in both places. The upgrade of Ruby is what produces the difference.

require 'active_support/all' # version 7.1.5.1

int = 100
dur = 100.seconds # ActiveSupport/Duration

# The bug

(dur..dur).step(10).to_a  # => Ruby 3.3 returns [100 seconds] - CORRECT
                          # => Ruby 3.4 returns [] - INCORRECT

(int..dur).step(10).to_a  # => Ruby 3.3 returns [100] - CORRECT
                          # => Ruby 3.4 returns [] - INCORRECT

# Note the following cases work correctly on both Ruby versions:
(int..int).step(10).to_a  #=> [100]
(int..dur).to_a           #=> [100]

# Range with non-equivalent values also works fine on different versions:
dur2 = 120.seconds
(dur..dur2).step(10).to_a  #=> [100 seconds, 110 seconds, 120 seconds]
(int..dur2).step(10).to_a  #=> [100, 110, 120]

[zverok (Victor Shepelev)]

• Assignee set to zverok (Victor Shepelev)
• Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN to 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: UNKNOWN

[zverok (Victor Shepelev)]

Confirmed, looking into it.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset git|f56f3eaae55cc6f8d9e79862ee73a9ffb53d6077.

---

[Bug #21030] Fix step for non-numeric range

When the end points of an inclusive range equal, Range#step should
yields the element once.

[johnnyshields (Johnny Shields)]

May I confirm this will be patched in Ruby 3.4.2?

[nobu (Nobuyoshi Nakada)]

3.4.2 is not scheduled yet.

[johnnyshields (Johnny Shields)]

May we mark this as 3.4 backport? I'm hesitant to upgrade my app to 3.4 without this fix.

[mame (Yusuke Endoh)]

• Related to Bug #21147: [Breaking changes or Bug] DateTime Range#to_a behaves different between 3.3.7 and 3.4.1 added

[jamesst20 (James St-Pierre)]

According to the changelogs for v3.4.2, this wasn't included?

https://github.com/ruby/ruby/releases/tag/v3_4_2

[Eregon (Benoit Daloze)]

• Backport changed from 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: UNKNOWN to 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: REQUIRED