Bug #12884: Using a HashWithIndifferentAccess with a default value in a function with a keyword parameter converts it to a Hash.

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.3.1
• Backport: 2.1: DONTNEED, 2.2: DONE, 2.3: DONE, 2.4: DONE

[mderelle (Mathieu Derelle)]

A strange bug that broke our production when migrating from 2.1.9 to 2.2.5 (still present in 2.3.1)
It involves HashWithIndifferentAccess from active support. The version used is 3.2.22.4 (against all ruby versions)

Here's a bit of code to reproduce it :

def test(params = HashWithIndifferentAccess.new, disrupter: nil)
	params.class
end

x = HashWithIndifferentAccess.new
x[:foo] = 'bar'
test x
# 2.3.1 => Hash
# 2.2.5 => Hash
# 2.1.9 => HashWithIndifferentAccess

But this only happens if there is a keyword parameter AND a default value for your HashWithIndifferentAccess parameter :

Not using a keyword parameter doesn't change the type

def test(params = HashWithIndifferentAccess.new, disrupter = nil)
	params.class
end

x = HashWithIndifferentAccess.new
x[:foo] = 'bar'
test x
# 2.3.1 => HashWithIndifferentAccess
# 2.2.5 => HashWithIndifferentAccess
# 2.1.9 => HashWithIndifferentAccess

Not using a default value don't change the type

def test(params, disrupter: nil)
	params.class
end

x = HashWithIndifferentAccess.new
x[:foo] = 'bar'
test x
# 2.3.1 => HashWithIndifferentAccess
# 2.2.5 => HashWithIndifferentAccess
# 2.1.9 => HashWithIndifferentAccess

[shyouhei (Shyouhei Urabe)]

(Just to be clear) It has nothing to do with HWIA. I can reproduce the situation without it.

class X < Hash; end

def test(params = X.new, disrupter: nil)
  return params
end

x = X.new
x['foo'] = 'bar'
p test(x).class

[shyouhei (Shyouhei Urabe)]

• Is duplicate of Bug #12821: Object converted to Hash unexpectedly under certain method call added

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r57360.

---

class.c: non-keyword hash class

• class.c (rb_extract_keywords): keep the class of non-keyword
  elements hash as the original. [ruby-core:77813] [Bug #12884]

[naruse (Yui NARUSE)]

• Backport changed from 2.1: DONTNEED, 2.2: REQUIRED, 2.3: REQUIRED to 2.1: DONTNEED, 2.2: REQUIRED, 2.3: REQUIRED, 2.4: DONE

ruby_2_4 r57861 merged revision(s) 57360.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.1: DONTNEED, 2.2: REQUIRED, 2.3: REQUIRED, 2.4: DONE to 2.1: DONTNEED, 2.2: DONE, 2.3: REQUIRED, 2.4: DONE

ruby_2_2 r58092 merged revision(s) 57360.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.1: DONTNEED, 2.2: DONE, 2.3: REQUIRED, 2.4: DONE to 2.1: DONTNEED, 2.2: DONE, 2.3: DONE, 2.4: DONE

ruby_2_3 r58167 merged revision(s) 57360.