chore: remove tokio-futures facade crate (#1327)

This switches from using the tokio-futures facade to referencing
futures-* crates directly.

tokio-sync/Cargo.toml

@@ -22,13 +22,13 @@ categories = ["asynchronous"]
 publish = false
 
 [features]
-async-traits = ["tokio-futures"]
+async-traits = ["futures-sink-preview"]
 
 [dependencies]
 async-util = { git = "https://github.com/tokio-rs/async" }
-tokio-futures = { path = "../tokio-futures", optional = true }
 fnv = "1.0.6"
 futures-core-preview = { version = "0.3.0-alpha.17" }
+futures-sink-preview = { version = "0.3.0-alpha.17", optional = true }
 
 [dev-dependencies]
 env_logger = { version = "0.5", default-features = false }

tokio-sync/src/mpsc/bounded.rs

@@ -214,7 +214,7 @@ impl<T> Sender<T> {
 }
 
 #[cfg(feature = "async-traits")]
-impl<T> tokio_futures::Sink<T> for Sender<T> {
+impl<T> futures_sink::Sink<T> for Sender<T> {
     type Error = SendError;
 
     fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {

tokio-sync/src/mpsc/unbounded.rs

@@ -130,7 +130,7 @@ impl<T> UnboundedSender<T> {
 }
 
 #[cfg(feature = "async-traits")]
-impl<T> tokio_futures::Sink<T> for UnboundedSender<T> {
+impl<T> futures_sink::Sink<T> for UnboundedSender<T> {
     type Error = UnboundedSendError;
 
     fn poll_ready(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {

tokio-sync/src/watch.rs

@@ -368,7 +368,7 @@ impl<T> Sender<T> {
 }
 
 #[cfg(feature = "async-traits")]
-impl<T> tokio_futures::Sink<T> for Sender<T> {
+impl<T> futures_sink::Sink<T> for Sender<T> {
     type Error = error::SendError<T>;
 
     fn poll_ready(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {

tokio-sync/tests/mpsc.rs

@@ -57,8 +57,8 @@ async fn async_send_recv_with_buffer() {
 #[cfg(feature = "async-traits")]
 fn send_sink_recv_with_buffer() {
     use futures_core::Stream;
+    use futures_sink::Sink;
     use pin_utils::pin_mut;
-    use tokio_futures::Sink;
 
     let mut t1 = MockTask::new();
 
@@ -170,8 +170,8 @@ async fn async_send_recv_unbounded() {
 #[cfg(feature = "async-traits")]
 fn sink_send_recv_unbounded() {
     use futures_core::Stream;
+    use futures_sink::Sink;
     use pin_utils::pin_mut;
-    use tokio_futures::Sink;
 
     let mut t1 = MockTask::new();