Fix problem with accessing constant proxy subclass

This commit fixes #36313.

After #32065 moved `SourceAnnotationExtractor` into `Rails` module, it
broke the ability to access `SourceAnnotationExtractor::Annotate`
directly as user would get this error:

    TypeError: Rails::SourceAnnotationExtractor is not a class/module

This commit fixes the issue by making `DeprecatedConstantProxy` to
inherit from `Module` and then defines `method_missing` and
`const_missing` to retain the previous functionality.

Thank you Matthew Draper for the idea of how to fix the issue!

[Prem Sichanugrist & Matthew Draper]

1 files changed, 17 insertions, 0 deletions

diff --git a/activesupport/test/deprecation_test.rb b/activesupport/test/deprecation_test.rb
index f25c704586..ae2f4a6e58 100644
--- a/activesupport/test/deprecation_test.rb
+++ b/activesupport/test/deprecation_test.rb
@@ -38,6 +38,11 @@ class Deprecatee
     C = 1
   end
   A = ActiveSupport::Deprecation::DeprecatedConstantProxy.new("Deprecatee::A", "Deprecatee::B::C")
+
+  module New
+    class Descendant; end
+  end
+  Old = ActiveSupport::Deprecation::DeprecatedConstantProxy.new("Deprecatee::Old", "Deprecatee::New")
 end
 
 class DeprecateeWithAccessor
@@ -210,6 +215,18 @@ class DeprecationTest < ActiveSupport::TestCase
     assert_not_deprecated { assert_equal Deprecatee::B::C.class, Deprecatee::A.class }
   end
 
+  def test_deprecated_constant_descendant
+    assert_not_deprecated { Deprecatee::New::Descendant }
+
+    assert_deprecated("Deprecatee::Old") do
+      assert_equal Deprecatee::Old::Descendant, Deprecatee::New::Descendant
+    end
+
+    assert_raises(NameError) do
+      assert_deprecated("Deprecatee::Old") { Deprecatee::Old::NON_EXISTENCE }
+    end
+  end
+
   def test_deprecated_constant_accessor
     assert_not_deprecated { DeprecateeWithAccessor::B::C }
     assert_deprecated("DeprecateeWithAccessor::A") { assert_equal DeprecateeWithAccessor::B::C, DeprecateeWithAccessor::A }