Bug #12863: Hash#compact! behavior different from the Active Support Hash#compact!

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[cha1tanya (Prathamesh Sonpatki)]

Hash#compact and Hash#compact! were added in https://bugs.ruby-lang.org/issues/11818 but the Hash#compact! is different from Active Support. Please check following snippet:

# Active Support
>> hash = { a: true, b: false, c: nil }
=> {:a=>true, :b=>false, :c=>nil}
>> hash.compact!
=> {:a=>true, :b=>false}
>> hash.compact!
=> nil

# Ruby dev

>> hash = { a: true, b: false, c: nil }
=> {:a=>true, :b=>false, :c=>nil}
>> hash.compact!
=> {:a=>true, :b=>false}
>> hash.compact!
=> {:a=>true, :b=>false}
>> 

@nobu (Nobuyoshi Nakada) Was it intentional to not return nil in case of compact! when none of the values are nil?

[zverok (Victor Shepelev)]

What is the reason of returning nil in that case? I believe in standard containers all bang-versions always return self?

[zverok (Victor Shepelev)]

Hm, looks like returning nil (if nothing was dropped) is standard behavior of Hash#reject!. Weird.

[nobu (Nobuyoshi Nakada)]

• Tracker changed from Misc to Bug
• Backport set to 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r56473.

---

hash.c: fix Hash#compact! return value

• hash.c (rb_hash_compact_bang): should return nil if no elements
  is deleted. [ruby-core:77709] [Bug #12863]