runtime/race: Race detector does not detect len(c) / {send,recv}(c) race

[randall77]

The race detector should report a race when one goroutine is reading the length of a channel and another is reading or writing to the channel.

func main() {
    res := make(chan int, 1)
    ch := make(chan bool, 1)
    go func() { ch <- true }()
    go func() { res <- len(ch) }()
    fmt.Println(<-res)
}

@dvyukov

[bradfitz]

Thread: https://groups.google.com/forum/#!topic/golang-dev/GRreaKlQSjc

[dvyukov]

http://golang.org/ref/spec#Channel_types

A single channel may be used in send statements, receive operations, and calls to the built-in functions cap and len by any number of goroutines without further synchronization.