fails to flag ineffectual reassignment after usage of waitgroups/errorgroups

[wkalt]

This program ineffectually reassigns a value after modification within a waitgroup:

func test() error {
	var sharedValue int
	mtx := &sync.Mutex{}
	wg := &sync.WaitGroup{}
	for i := 0; i < 3; i++ {
		wg.Add(1)
		go func() {
			mtx.Lock()
			sharedValue++
			mtx.Unlock()
			wg.Done()
		}()
	}

	wg.Wait()

	// should be flagged
	sharedValue = 0

	return nil
}

The commented reassignment seems like it should be flagged. I suspect the rationale for not flagging it may be that it is modified within a goroutine, and therefor could be reused. However due to the usage of a waitgroup, this assignment is in fact ineffectual.

The same issue can exist with errgroups and with goroutines coordinated over a channel. Is this a bug?

[gordonklaus]

You are correct: Any variable accessed in another goroutine is thereafter ignored by the tool. In general, it may be arbitrarily complex to determine in what order such a variable is accessed.