(lang_diagnostic_starter, lang_diagnostic_finalizer): New objects.
(error_module_changed, record_last_error_module,
error_function_changed, record_last_error_function): New functions.
(lang_diagnostic_starter, lang_diagnostic_finalizer): New objects.
(error_module_changed, record_last_error_module,
error_function_changed, record_last_error_function): New functions.