Merge pull request #4107 from rmosolgo/2.0.9-handle-array-prev_type

Fix #add_type for duplicate types with cyclical references

Author: rmosolgo

lib/graphql/schema/addition.rb

@@ -151,7 +151,7 @@ def add_type(type, owner:, late_types:, path:)
           um << owner
         end
 
-        if (prev_type = get_local_type(type.graphql_name)) && prev_type == type
+        if (prev_type = get_local_type(type.graphql_name)) && (prev_type == type || (prev_type.is_a?(Array) && prev_type.include?(type)))
           # No need to re-visit
         elsif type.is_a?(Class) && type < GraphQL::Schema::Directive
           @directives << type

spec/graphql/schema/addition_spec.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+require "spec_helper"
+
+describe GraphQL::Schema::Addition do
+  it "handles duplicate types with cycles" do
+    duplicate_types_schema = Class.new(GraphQL::Schema)
+    duplicate_types = 2.times.map {
+      Class.new(GraphQL::Schema::Object) do
+        graphql_name "Thing"
+        field :thing, self
+      end
+    }
+    duplicate_types_schema.orphan_types(duplicate_types)
+    assert_equal 2, duplicate_types_schema.send(:own_types)["Thing"].size
+  end
+end