From 894c83170bd5f638de020c97dc46efe4d8f97803 Mon Sep 17 00:00:00 2001
From: Toralf Wittner <tw@dtex.org>
Date: Thu, 12 Dec 2019 14:18:45 +0100
Subject: [PATCH] Bring back phantom types to yamux upgrade outputs.

---
 muxers/yamux/src/lib.rs | 94 ++++++++++++++++++++++++++---------------
 1 file changed, 59 insertions(+), 35 deletions(-)

diff --git a/muxers/yamux/src/lib.rs b/muxers/yamux/src/lib.rs
index c4745fd4..507a1bea 100644
--- a/muxers/yamux/src/lib.rs
+++ b/muxers/yamux/src/lib.rs
@@ -21,7 +21,7 @@
 //! Implements the Yamux multiplexing protocol for libp2p, see also the
 //! [specification](https://github.com/hashicorp/yamux/blob/master/spec.md).
 
-use futures::{future, prelude::*, ready};
+use futures::{future, prelude::*, ready, stream::{BoxStream, LocalBoxStream}};
 use libp2p_core::upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, Negotiated};
 use parking_lot::Mutex;
 use std::{fmt, io, iter, pin::Pin, task::Context};
@@ -49,17 +49,20 @@ struct Inner<S> {
 #[derive(Debug)]
 pub struct OpenSubstreamToken(());
 
-impl Yamux<Incoming> {
+impl<C> Yamux<Incoming<C>>
+where
+    C: AsyncRead + AsyncWrite + Send + Unpin + 'static
+{
     /// Create a new Yamux connection.
-    pub fn new<C>(io: C, mut cfg: yamux::Config, mode: yamux::Mode) -> Self
-    where
-        C: AsyncRead + AsyncWrite + Send + Unpin + 'static
-    {
+    pub fn new(io: C, mut cfg: yamux::Config, mode: yamux::Mode) -> Self {
         cfg.set_read_after_close(false);
         let conn = yamux::Connection::new(io, cfg, mode);
         let ctrl = conn.control();
         let inner = Inner {
-            incoming: Incoming(Box::pin(yamux::into_stream(conn).err_into())),
+            incoming: Incoming {
+                stream: yamux::into_stream(conn).err_into().boxed(),
+                _marker: std::marker::PhantomData
+            },
             control: ctrl,
             acknowledged: false
         };
@@ -67,17 +70,20 @@ impl Yamux<Incoming> {
     }
 }
 
-impl Yamux<LocalIncoming> {
+impl<C> Yamux<LocalIncoming<C>>
+where
+    C: AsyncRead + AsyncWrite + Unpin + 'static
+{
     /// Create a new Yamux connection (which is ![`Send`]).
-    pub fn local<C>(io: C, mut cfg: yamux::Config, mode: yamux::Mode) -> Self
-    where
-        C: AsyncRead + AsyncWrite + Unpin + 'static
-    {
+    pub fn local(io: C, mut cfg: yamux::Config, mode: yamux::Mode) -> Self {
         cfg.set_read_after_close(false);
         let conn = yamux::Connection::new(io, cfg, mode);
         let ctrl = conn.control();
         let inner = Inner {
-            incoming: LocalIncoming(Box::pin(yamux::into_stream(conn).err_into())),
+            incoming: LocalIncoming {
+                stream: yamux::into_stream(conn).err_into().boxed_local(),
+                _marker: std::marker::PhantomData
+            },
             control: ctrl,
             acknowledged: false
         };
@@ -199,9 +205,9 @@ impl<C> InboundUpgrade<C> for Config
 where
     C: AsyncRead + AsyncWrite + Send + Unpin + 'static
 {
-    type Output = Yamux<Incoming>;
+    type Output = Yamux<Incoming<Negotiated<C>>>;
     type Error = io::Error;
-    type Future = future::Ready<Result<Yamux<Incoming>, Self::Error>>;
+    type Future = future::Ready<Result<Self::Output, Self::Error>>;
 
     fn upgrade_inbound(self, io: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ready(Ok(Yamux::new(io, self.0, yamux::Mode::Server)))
@@ -212,9 +218,9 @@ impl<C> InboundUpgrade<C> for LocalConfig
 where
     C: AsyncRead + AsyncWrite + Unpin + 'static
 {
-    type Output = Yamux<LocalIncoming>;
+    type Output = Yamux<LocalIncoming<Negotiated<C>>>;
     type Error = io::Error;
-    type Future = future::Ready<Result<Yamux<LocalIncoming>, Self::Error>>;
+    type Future = future::Ready<Result<Self::Output, Self::Error>>;
 
     fn upgrade_inbound(self, io: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ready(Ok(Yamux::local(io, (self.0).0, yamux::Mode::Server)))
@@ -225,9 +231,9 @@ impl<C> OutboundUpgrade<C> for Config
 where
     C: AsyncRead + AsyncWrite + Send + Unpin + 'static
 {
-    type Output = Yamux<Incoming>;
+    type Output = Yamux<Incoming<Negotiated<C>>>;
     type Error = io::Error;
-    type Future = future::Ready<Result<Yamux<Incoming>, Self::Error>>;
+    type Future = future::Ready<Result<Self::Output, Self::Error>>;
 
     fn upgrade_outbound(self, io: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ready(Ok(Yamux::new(io, self.0, yamux::Mode::Client)))
@@ -238,9 +244,9 @@ impl<C> OutboundUpgrade<C> for LocalConfig
 where
     C: AsyncRead + AsyncWrite + Unpin + 'static
 {
-    type Output = Yamux<LocalIncoming>;
+    type Output = Yamux<LocalIncoming<Negotiated<C>>>;
     type Error = io::Error;
-    type Future = future::Ready<Result<Yamux<LocalIncoming>, Self::Error>>;
+    type Future = future::Ready<Result<Self::Output, Self::Error>>;
 
     fn upgrade_outbound(self, io: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ready(Ok(Yamux::local(io, (self.0).0, yamux::Mode::Client)))
@@ -259,31 +265,49 @@ impl Into<io::Error> for YamuxError {
 }
 
 /// The [`futures::stream::Stream`] of incoming substreams.
-pub struct Incoming(Pin<Box<dyn Stream<Item = Result<yamux::Stream, YamuxError>> + Send>>);
+pub struct Incoming<T> {
+    stream: BoxStream<'static, Result<yamux::Stream, YamuxError>>,
+    _marker: std::marker::PhantomData<T>
+}
+
+impl<T> fmt::Debug for Incoming<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("Incoming")
+    }
+}
 
 /// The [`futures::stream::Stream`] of incoming substreams (`!Send`).
-pub struct LocalIncoming(Pin<Box<dyn Stream<Item = Result<yamux::Stream, YamuxError>>>>);
+pub struct LocalIncoming<T> {
+    stream: LocalBoxStream<'static, Result<yamux::Stream, YamuxError>>,
+    _marker: std::marker::PhantomData<T>
+}
 
-impl Stream for Incoming {
-    type Item = Result<yamux::Stream, YamuxError>;
-
-    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> std::task::Poll<Option<Self::Item>> {
-        self.0.poll_next_unpin(cx)
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.0.size_hint()
+impl<T> fmt::Debug for LocalIncoming<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("LocalIncoming")
     }
 }
 
-impl Stream for LocalIncoming {
+impl<T: Unpin> Stream for Incoming<T> {
     type Item = Result<yamux::Stream, YamuxError>;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> std::task::Poll<Option<Self::Item>> {
-        self.0.poll_next_unpin(cx)
+        self.stream.as_mut().poll_next_unpin(cx)
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        self.0.size_hint()
+        self.stream.size_hint()
+    }
+}
+
+impl<T: Unpin> Stream for LocalIncoming<T> {
+    type Item = Result<yamux::Stream, YamuxError>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> std::task::Poll<Option<Self::Item>> {
+        self.stream.as_mut().poll_next_unpin(cx)
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.stream.size_hint()
     }
 }