dirFiles: dirFiles,
		pkgs:     make(map[string]*futurePackage),
	}

	start := time.Now()

	// Though we read files while parsing, type-checking is otherwise CPU bound.
	//
	// This doesn't achieve great CPU utilization as many packages may block
	// waiting for a common import, but in combination with the non-deterministic
	// map iteration below this should provide decent coverage of concurrent
	// type-checking (see golang/go#47729).