Example:

x = [1,2,3,4]
y = [3,2,1]

def test x, y
  hash = {}
  x.zip(y) { |k,v| hash[k] = v }
  hash
end

def test2 x, y
  Hash[x.zip(y)]
end

def test3 x, y
  x.zip(y).each_with_object({}) { |(k,v),hash| hash[k] = v }
end

def stat num
  start = GC.stat(:total_allocated_object)
  num.times { yield }
  total_obj_count = GC.stat(:total_allocated_object) - start
  puts "#{total_obj_count / num} allocations per call"
end

stat(100) { test(x,y) }
stat(100) { test2(x,y) }
stat(100) { test3(x,y) }

__END__
2 allocations per call
7 allocations per call
8 allocations per call

Fix typo guides/source/active_support_instrumentation.md [ci-skip]

fixes in active record query for reorder in rails guides

Rename `oid_type` to `cast_type` to make PG columns consistent with abstract columns

Add missing nodoc

Fix serialized field returning serialized data after update_column

Conflicts:
	activerecord/CHANGELOG.md

This reverts commit 9a1abedc, reversing
changes made to c72d6c91.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/models/comment.rb

This change break integration with activerecord-deprecated_finders so
I'm reverting until we find a way to make it work with this gem.

fix formatting and text for ActionController::Redirecting doc

  - `extract_precision`, `extract_limit`, and `extract_default` probably need to follow.
  - would be good to remove the delegation `Column#extract_scale`.

/cc @sgrif

- Added assertions about the column. Specifically scale.
- Move record insertion from setup into test method.

Fix polymorphic eager load with foreign_key as String.

The foreign_key could be `String` and just doing `owners_map[owner_key]`
could return `nil`.
To prevent this bug, we should `to_s` both keys if their types are
different.

Fixes #14734.

Remove redundant code.

Hash#deep_*_keys(!) recurse into nested arrays.

Conflicts:
	activesupport/CHANGELOG.md

Fixes Issue #13466.

Conflicts:
	activerecord/CHANGELOG.md

Delegate `klass` to the injected type object

Making belongs_to: touch behaviour be consistent with save updating updated_at

This reverts commit e94e6c27.

Conflicts:
	activerecord/CHANGELOG.md

The original commit was reverted only to be safe since #14407 were reported.
We don't have any proof we added a regression with the original commit
so reverting it now will give us more problem.

Closes #14407

Put attr_reader in with all of the other instance methods

Delegate `type_cast_for_write` to injected type object