Merge pull request #16357 from gchan/hwia-respects-to-hash-default

`HashWithIndifferentAccess.new` respects the default value or proc on
objects that respond to `#to_hash`

activesupport/CHANGELOG.md

+*   `HashWithIndifferentAccess.new` respects the default value or proc on objects
+    that respond to `#to_hash`. `.new_from_hash_copying_default` simply invokes `.new`.
+    All calls to `.new_from_hash_copying_default` are replaced with `.new`.
+
+    *Gordon Chan*
+
 *   Change Integer#year to return a Fixnum instead of a Float to improve
     consistency.
 

activesupport/lib/active_support/core_ext/hash/indifferent_access.rb

@@ -6,7 +6,7 @@ class Hash
   #
   #   { a: 1 }.with_indifferent_access['a'] # => 1
   def with_indifferent_access
-    ActiveSupport::HashWithIndifferentAccess.new_from_hash_copying_default(self)
+    ActiveSupport::HashWithIndifferentAccess.new(self)
   end
 
   # Called when object is nested under an object that receives

activesupport/lib/active_support/hash_with_indifferent_access.rb

@@ -59,6 +59,10 @@ def initialize(constructor = {})
       if constructor.respond_to?(:to_hash)
         super()
         update(constructor)
+
+        hash = constructor.to_hash
+        self.default = hash.default if hash.default
+        self.default_proc = hash.default_proc if hash.default_proc
       else
         super(constructor)
       end
@@ -73,11 +77,7 @@ def default(key = nil)
     end
 
     def self.new_from_hash_copying_default(hash)
-      hash = hash.to_hash
-      new(hash).tap do |new_hash|
-        new_hash.default = hash.default
-        new_hash.default_proc = hash.default_proc if hash.default_proc
-      end
+      new(hash)
     end
 
     def self.[](*args)
@@ -206,7 +206,7 @@ def merge(hash, &block)
     #   hash['a'] = nil
     #   hash.reverse_merge(a: 0, b: 1) # => {"a"=>nil, "b"=>1}
     def reverse_merge(other_hash)
-      super(self.class.new_from_hash_copying_default(other_hash))
+      super(self.class.new(other_hash))
     end
 
     # Same semantics as +reverse_merge+ but modifies the receiver in-place.
@@ -219,7 +219,7 @@ def reverse_merge!(other_hash)
     #   h = { "a" => 100, "b" => 200 }
     #   h.replace({ "c" => 300, "d" => 400 }) # => {"c"=>300, "d"=>400}
     def replace(other_hash)
-      super(self.class.new_from_hash_copying_default(other_hash))
+      super(self.class.new(other_hash))
     end
 
     # Removes the specified key from the hash.

activesupport/test/core_ext/hash_ext_test.rb

@@ -1044,6 +1044,24 @@ def test_new_from_hash_copying_default_should_not_raise_when_default_proc_does
 
     assert_nothing_raised { HashWithIndifferentAccess.new_from_hash_copying_default(hash) }
   end
+
+  def test_new_with_to_hash_conversion_copies_default
+    normal_hash = Hash.new(3)
+    normal_hash[:a] = 1
+
+    hash = HashWithIndifferentAccess.new(HashByConversion.new(normal_hash))
+    assert_equal 1, hash[:a]
+    assert_equal 3, hash[:b]
+  end
+
+  def test_new_with_to_hash_conversion_copies_default_proc
+    normal_hash = Hash.new { 1 + 2 }
+    normal_hash[:a] = 1
+
+    hash = HashWithIndifferentAccess.new(HashByConversion.new(normal_hash))
+    assert_equal 1, hash[:a]
+    assert_equal 3, hash[:b]
+  end
 end
 
 class IWriteMyOwnXML