unique_constraint_options

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 752
        def unique_constraint_options(table_name, column_name, options) # :nodoc:
          assert_valid_deferrable(options[:deferrable])

          if column_name && options[:using_index]
            raise ArgumentError, "Cannot specify both column_name and :using_index options."
          end

          options = options.dup
          options[:name] ||= unique_constraint_name(table_name, column: column_name, **options)
          options
        end