Add must_use to futures, deny missing docs (#171)

src/frame/reason.rs

@@ -1,25 +1,56 @@
 use std::fmt;
 
 
+/// HTTP2 Error codes
+///
+/// See [Error Codes in the spec][spec].
+///
+/// [spec}: http://httpwg.org/specs/rfc7540.html#ErrorCodes
 #[derive(PartialEq, Eq, Clone, Copy)]
 pub struct Reason(u32);
 
 impl Reason {
+    /// The associated condition is not a result of an error.
+    ///
+    /// For example, a GOAWAY might include this code to indicate graceful
+    /// shutdown of a connection.
     pub const NO_ERROR: Reason = Reason(0);
+    /// The endpoint detected an unspecific protocol error.
+    ///
+    /// This error is for use when a more specific error code is not available.
     pub const PROTOCOL_ERROR: Reason = Reason(1);
+    /// The endpoint encountered an unexpected internal error.
     pub const INTERNAL_ERROR: Reason = Reason(2);
+    /// The endpoint detected that its peer violated the flow-control protocol.
     pub const FLOW_CONTROL_ERROR: Reason = Reason(3);
+    /// The endpoint sent a SETTINGS frame but did not receive a response in
+    /// a timely manner.
     pub const SETTINGS_TIMEOUT: Reason = Reason(4);
+    /// The endpoint received a frame after a stream was half-closed.
     pub const STREAM_CLOSED: Reason = Reason(5);
+    /// The endpoint received a frame with an invalid size.
     pub const FRAME_SIZE_ERROR: Reason = Reason(6);
+    /// The endpoint refused the stream prior to performing any application
+    /// processing.
     pub const REFUSED_STREAM: Reason = Reason(7);
+    /// Used by the endpoint to indicate that the stream is no longer needed.
     pub const CANCEL: Reason = Reason(8);
+    /// The endpoint is unable to maintain the header compression context for
+    /// the connection.
     pub const COMPRESSION_ERROR: Reason = Reason(9);
+    /// The connection established in response to a CONNECT request was reset
+    /// or abnormally closed.
     pub const CONNECT_ERROR: Reason = Reason(10);
+    /// The endpoint detected that its peer is exhibiting a behavior that might
+    /// be generating excessive load.
     pub const ENHANCE_YOUR_CALM: Reason = Reason(11);
+    /// The underlying transport has properties that do not meet minimum
+    /// security requirements.
     pub const INADEQUATE_SECURITY: Reason = Reason(12);
-    pub const HTTP11_REQUIRED: Reason = Reason(13);
+    /// The endpoint requires that HTTP/1.1 be used instead of HTTP/2.
+    pub const HTTP_1_1_REQUIRED: Reason = Reason(13);
 
+    /// Get a string description of the error code.
     pub fn description(&self) -> &str {
         match self.0 {
             0 => "not a result of an error",