The list of warnings below should NEVER grow. It should gradually shrink to 0.
-CHECK: Warnings without flags (158):
+CHECK: Warnings without flags (159):
CHECK-NEXT: pp_include_next_absolute_path
CHECK-NEXT: pp_include_next_in_primary
CHECK-NEXT: pp_invalid_string_literal
CHECK-NEXT: warn_drv_pch_not_first_include
CHECK-NEXT: warn_drv_preprocessed_input_file_unused
CHECK-NEXT: warn_dup_category_def
+CHECK-NEXT: warn_duplicate_attribute
CHECK-NEXT: warn_duplicate_protocol_def
CHECK-NEXT: warn_enum_too_large
CHECK-NEXT: warn_enum_value_overflow