What happens when writing to an uninitialized (nil) channel?

In Go, writing to an uninitialized (nil) channel causes the goroutine to block forever, because a nil channel is not ready to send or receive data.

Example:

var ch chan int // ch == nil

func main() {
    ch <- 1 // blocks forever, because the channel is nil
}

This behavior is sometimes used for dynamically enabling/disabling channels in select statements, since operations on a nil channel never execute and block the goroutine.