fix: Remove Pin API related unsafe code

Author: k-nasa

src/future/future/delay.rs

@@ -2,21 +2,23 @@ use std::pin::Pin;
 use std::time::Duration;
 
 use futures_timer::Delay;
+use pin_project_lite::pin_project;
 
 use crate::future::Future;
 use crate::task::{Context, Poll};
 
+pin_project! {
 #[doc(hidden)]
 #[derive(Debug)]
-pub struct DelayFuture<F> {
-    future: F,
-    delay: Delay,
+    pub struct DelayFuture<F> {
+        #[pin]
+        future: F,
+        #[pin]
+        delay: Delay,
+    }
 }
 
 impl<F> DelayFuture<F> {
-    pin_utils::unsafe_pinned!(future: F);
-    pin_utils::unsafe_pinned!(delay: Delay);
-
     pub fn new(future: F, dur: Duration) -> DelayFuture<F> {
         let delay = Delay::new(dur);
 
@@ -27,10 +29,12 @@ impl<F> DelayFuture<F> {
 impl<F: Future> Future for DelayFuture<F> {
     type Output = F::Output;
 
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        match self.as_mut().delay().poll(cx) {
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = self.project();
+
+        match this.delay.poll(cx) {
             Poll::Pending => Poll::Pending,
-            Poll::Ready(_) => match self.future().poll(cx) {
+            Poll::Ready(_) => match this.future.poll(cx) {
                 Poll::Ready(v) => Poll::Ready(v),
                 Poll::Pending => Poll::Pending,
             },