Waitgroup.done wont Panic?

[sperber...@googlemail.com]

Hi Folks,

Here:
https://play.golang.org/p/76AzuAiVGxL

I thougt If the waitgroup gets below 0 there should be a Panic.
I understand that the goroutine is canceled. So maybe the defer Statement is Not executed.
But why is there No warning at the end of Main that some goroutines Had to be canceled?

Thx
Yours
Stephan

[Jan Mercl]

wg.Wait at line 18 does not wait for anything and the program exists
before the goroutine executing func worker even starts. IOW, wg.Done
at line 10 is not executed hence no panic.

[Jake Montgomery]

To clarify what Jan said, a Go program exits when main() exits. Since `wg` has a count of 0, the call to wg.Wait() on like 18 doe not wat, so the program exits before your goroutine even has time to run. With slight modification, it does panic as expected: https://play.golang.org/p/ivcfhsu1N9K