deal with Array arguments to #order

activerecord/lib/active_record/relation/query_methods.rb

@@ -930,7 +930,19 @@ module ActiveRecord
 
       # Extract column names from arguments passed to #order or #reorder.
       def column_names_from_order_arguments(args)
-        args.flat_map { |arg| arg.is_a?(Hash) ? arg.keys : arg }
+        args.flat_map do |arg|
+          case arg
+          when Hash
+            # Tag.order(id: :desc)
+            arg.keys
+          when Array
+            # Tag.order([Arel.sql("field(id, ?)"), [1, 3, 2]])
+            arg.flatten
+          else
+            # Tag.order(:id)
+            arg
+          end
+        end
       end
 
       def assert_mutability!

activerecord/lib/active_record/sanitization.rb

@@ -63,6 +63,12 @@ module ActiveRecord
         #   # => "id ASC"
         def sanitize_sql_for_order(condition) # :doc:
           if condition.is_a?(Array) && condition.first.to_s.include?("?")
+            # Ensure we aren't dealing with a subclass of String that might
+            # override methods we use (eg. Arel::Nodes::SqlLiteral).
+            if condition.first.kind_of?(String) && !condition.first.instance_of?(String)
+              condition = [String.new(condition.first), *condition[1..-1]]
+            end
+
             sanitize_sql_array(condition)
           else
             condition

activerecord/test/cases/relations_test.rb

@@ -389,13 +389,13 @@ class RelationTest < ActiveRecord::TestCase
   end
 
   def test_finding_with_sanitized_order
-    query = Tag.order(["field(id, ?)", [1, 3, 2]]).to_sql
+    query = Tag.order([Arel.sql("field(id, ?)"), [1, 3, 2]]).to_sql
     assert_match(/field\(id, 1,3,2\)/, query)
 
-    query = Tag.order(["field(id, ?)", []]).to_sql
+    query = Tag.order([Arel.sql("field(id, ?)"), []]).to_sql
     assert_match(/field\(id, NULL\)/, query)
 
-    query = Tag.order(["field(id, ?)", nil]).to_sql
+    query = Tag.order([Arel.sql("field(id, ?)"), nil]).to_sql
     assert_match(/field\(id, NULL\)/, query)
   end