Avoid lifetime inference errors

rust-lang · Sep 5, 2020 · c447e5e · c447e5e
1 parent 38db3c1
commit c447e5e
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Showing 2 changed files with 7 additions and 30 deletions.
diff --git a/futures-test/src/assert_unmoved.rs b/futures-test/src/assert_unmoved.rs
@@ -40,7 +40,7 @@ impl<T> AssertUnmoved<T> {
         }
     }
 
-    fn poll_with<U>(mut self: Pin<&mut Self>, f: impl FnOnce(Pin<&mut T>) -> U) -> U {
+    fn poll_with<'a, U>(mut self: Pin<&'a mut Self>, f: impl FnOnce(Pin<&'a mut T>) -> U) -> U {
         let cur_this = &*self as *const Self;
         if self.this_ptr.is_null() {
             // First time being polled
@@ -158,19 +158,8 @@ impl<S: AsyncSeek> AsyncSeek for AssertUnmoved<S> {
 }
 
 impl<R: AsyncBufRead> AsyncBufRead for AssertUnmoved<R> {
-    fn poll_fill_buf(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
-        // FIXME: We cannot use `poll_with` here because it causes a lifetime error.
-        let cur_this = &*self as *const Self;
-        if self.this_ptr.is_null() {
-            // First time being polled
-            *self.as_mut().project().this_ptr = cur_this;
-        } else {
-            assert_eq!(
-                self.this_ptr, cur_this,
-                "AssertUnmoved moved between poll calls"
-            );
-        }
-        self.project().inner.poll_fill_buf(cx)
+    fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
+        self.poll_with(|r| r.poll_fill_buf(cx))
     }
 
     fn consume(self: Pin<&mut Self>, amt: usize) {

diff --git a/futures-test/src/interleave_pending.rs b/futures-test/src/interleave_pending.rs
@@ -57,10 +57,10 @@ impl<T> InterleavePending<T> {
         self.inner
     }
 
-    fn poll_with<U>(
-        self: Pin<&mut Self>,
+    fn poll_with<'a, U>(
+        self: Pin<&'a mut Self>,
         cx: &mut Context<'_>,
-        f: impl FnOnce(Pin<&mut T>, &mut Context<'_>) -> Poll<U>,
+        f: impl FnOnce(Pin<&'a mut T>, &mut Context<'_>) -> Poll<U>,
     ) -> Poll<U> {
         let this = self.project();
         if *this.pended {
@@ -185,19 +185,7 @@ impl<S: AsyncSeek> AsyncSeek for InterleavePending<S> {
 
 impl<R: AsyncBufRead> AsyncBufRead for InterleavePending<R> {
     fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
-        // FIXME: We cannot use `poll_with` here because it causes a lifetime error.
-        let this = self.project();
-        if *this.pended {
-            let next = this.inner.poll_fill_buf(cx);
-            if next.is_ready() {
-                *this.pended = false;
-            }
-            next
-        } else {
-            cx.waker().wake_by_ref();
-            *this.pended = true;
-            Poll::Pending
-        }
+        self.poll_with(cx, R::poll_fill_buf)
     }
 
     fn consume(self: Pin<&mut Self>, amount: usize) {