Document what happens when Receiver::recv() is called on a closed channel when there are queued messages

[daboross]

http://doc.rust-lang.org/std/sync/mpsc/struct.Receiver.html#method.recv states that if the sender has disconnected, an Err result is returned. This is only partially true - recv() will first run on every message that was queued before the Sender disconnected, then return err.

Example of this: https://play.rust-lang.org/?gist=f9d9741f1e5ae5dca3c1&version=stable

I think the documentation deserves at least a mention of this behavior - as it is kind of ambiguous whether the receiver will return Err even if there are messages queued or not just reading the current documentation.

[steveklabnik]

cc @rust-lang/libs , is this the actual behavior we want? if so, I can document it

[aturon]

@steveklabnik Yes, this is the intended behavior.