-Xfrontend -report-errors-to-debugger になるぽい。 https://github.com/apple/swift/blob/master/include/swift/Option/FrontendOptions.td#L297-L298
def report_errors_to_debugger : Flag<["-"], "report-errors-to-debugger">, HelpText<"Invoke the debugger hook on fatalError calls">;