Merge pull request #24031 from samphilipd/sam/do_not_clobber_options_in_route_definitions

Do not destructively mutate passed options hash in route definitions

2 files changed, 14 insertions, 2 deletions

diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 5a747b5f17..ffd5b83ad3 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1,4 +1,3 @@
-require 'active_support/core_ext/hash/reverse_merge'
 require 'active_support/core_ext/hash/slice'
 require 'active_support/core_ext/enumerable'
 require 'active_support/core_ext/array/extract_options'
@@ -824,7 +823,7 @@ module ActionDispatch
               URL_OPTIONS.include?(k) && (v.is_a?(String) || v.is_a?(Fixnum))
             end
 
-            (options[:defaults] ||= {}).reverse_merge!(defaults)
+            options[:defaults] = defaults.merge(options[:defaults] || {})
           else
             block, options[:constraints] = options[:constraints], {}
           end
diff --git a/actionpack/test/dispatch/mapper_test.rb b/actionpack/test/dispatch/mapper_test.rb
index df27e41997..69098326b9 100644
--- a/actionpack/test/dispatch/mapper_test.rb
+++ b/actionpack/test/dispatch/mapper_test.rb
@@ -178,6 +178,19 @@ module ActionDispatch
           mapper.mount as: "exciting"
         end
       end
+
+      def test_scope_does_not_destructively_mutate_default_options
+        fakeset = FakeSet.new
+        mapper = Mapper.new fakeset
+
+        frozen = { foo: :bar }.freeze
+
+        assert_nothing_raised do
+          mapper.scope(defaults: frozen) do
+            # pass
+          end
+        end
+      end
     end
   end
 end