Merge pull request #272 from cramertj/must-use

Set Future types as must_use

src/net/tcp.rs

@@ -25,6 +25,7 @@ pub struct TcpListener {
 
 /// Stream returned by the `TcpListener::incoming` function representing the
 /// stream of sockets received from a listener.
+#[must_use = "streams do nothing unless polled"]
 pub struct Incoming {
     inner: TcpListener,
 }
@@ -235,10 +236,12 @@ pub struct TcpStream {
 
 /// Future returned by `TcpStream::connect` which will resolve to a `TcpStream`
 /// when the stream is connected.
+#[must_use = "futures do nothing unless polled"]
 pub struct TcpStreamNew {
     inner: TcpStreamNewState,
 }
 
+#[must_use = "futures do nothing unless polled"]
 enum TcpStreamNewState {
     Waiting(TcpStream),
     Error(io::Error),