Merge pull request #910 from taiki-e/pin-project-lite

Update pin-project-lite to 0.2.0

Cargo.toml

@@ -71,7 +71,7 @@ log = { version = "0.4.8", features = ["kv_unstable"], optional = true }
 memchr = { version = "2.3.3", optional = true }
 num_cpus = { version = "1.12.0", optional = true }
 once_cell = { version = "1.3.1", optional = true }
-pin-project-lite = { version = "0.1.4", optional = true }
+pin-project-lite = { version = "0.2.0", optional = true }
 pin-utils = { version = "0.1.0-alpha.4", optional = true }
 slab = { version = "0.4.2", optional = true }
 

src/future/future/flatten.rs

@@ -1,26 +1,39 @@
+use pin_project_lite::pin_project;
 use std::future::Future;
 use std::pin::Pin;
 
 use crate::future::IntoFuture;
 use crate::task::{ready, Context, Poll};
 
-#[doc(hidden)]
-#[allow(missing_debug_implementations)]
-pub struct FlattenFuture<Fut1, Fut2> {
-    state: State<Fut1, Fut2>,
+pin_project! {
+    #[doc(hidden)]
+    #[allow(missing_debug_implementations)]
+    pub struct FlattenFuture<Fut1, Fut2> {
+        #[pin]
+        state: State<Fut1, Fut2>,
+    }
 }
 
-#[derive(Debug)]
-enum State<Fut1, Fut2> {
-    First(Fut1),
-    Second(Fut2),
-    Empty,
+pin_project! {
+    #[project = StateProj]
+    #[derive(Debug)]
+    enum State<Fut1, Fut2> {
+        First {
+            #[pin]
+            fut1: Fut1,
+        },
+        Second {
+            #[pin]
+            fut2: Fut2,
+        },
+        Empty,
+    }
 }
 
 impl<Fut1, Fut2> FlattenFuture<Fut1, Fut2> {
-    pub(crate) fn new(future: Fut1) -> FlattenFuture<Fut1, Fut2> {
+    pub(crate) fn new(fut1: Fut1) -> FlattenFuture<Fut1, Fut2> {
         FlattenFuture {
-            state: State::First(future),
+            state: State::First { fut1 },
         }
     }
 }
@@ -33,19 +46,19 @@ where
     type Output = <Fut1::Output as IntoFuture>::Output;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        let Self { state } = unsafe { self.get_unchecked_mut() };
+        let mut state = self.project().state;
         loop {
-            match state {
-                State::First(fut1) => {
-                    let fut2 = ready!(unsafe { Pin::new_unchecked(fut1) }.poll(cx)).into_future();
-                    *state = State::Second(fut2);
+            match state.as_mut().project() {
+                StateProj::First { fut1 } => {
+                    let fut2 = ready!(fut1.poll(cx)).into_future();
+                    state.set(State::Second { fut2 });
                 }
-                State::Second(fut2) => {
-                    let v = ready!(unsafe { Pin::new_unchecked(fut2) }.poll(cx));
-                    *state = State::Empty;
+                StateProj::Second { fut2 } => {
+                    let v = ready!(fut2.poll(cx));
+                    state.set(State::Empty);
                     return Poll::Ready(v);
                 }
-                State::Empty => panic!("polled a completed future"),
+                StateProj::Empty => panic!("polled a completed future"),
             }
         }
     }

src/net/addr.rs

@@ -68,6 +68,9 @@ pub enum ToSocketAddrsFuture<I> {
     Done,
 }
 
+// The field of `Self::Resolving` is `Unpin`, and the field of `Self::Ready` is never pinned.
+impl<I> Unpin for ToSocketAddrsFuture<I> {}
+
 /// Wrap `std::io::Error` with additional message
 ///
 /// Keeps the original error kind and stores the original I/O error as `source`.
@@ -84,7 +87,7 @@ impl<I: Iterator<Item = SocketAddr>> Future for ToSocketAddrsFuture<I> {
     type Output = io::Result<I>;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        let this = unsafe { self.get_unchecked_mut() };
+        let this = self.get_mut();
         let state = mem::replace(this, ToSocketAddrsFuture::Done);
 
         match state {