suggestions

tokio/src/sync/once_cell.rs

@@ -263,10 +263,10 @@ impl<T> OnceCell<T> {
     /// Moves the value out of the cell and drops the cell afterwards.
     ///
     /// Returns `None` if the cell is uninitialized.
-    pub fn into_inner(self) -> Option<T> {
+    pub fn into_inner(mut self) -> Option<T> {
         if self.initialized() {
             // Set to uninitialized for the destructor of `OnceCell` to work properly
-            self.value_set.store(false, Ordering::Release);
+            *self.value_set.get_mut() = false;
             Some(unsafe { self.value.with(|ptr| ptr::read(ptr).assume_init()) })
         } else {
             None

tokio/tests/sync_once_cell.rs

@@ -1,6 +1,7 @@
 #![warn(rust_2018_idioms)]
 #![cfg(feature = "full")]
 
+use std::mem;
 use std::ops::Drop;
 use std::sync::atomic::{AtomicU32, Ordering};
 use std::time::Duration;
@@ -181,7 +182,10 @@ fn drop_into_inner() {
 
     let once_cell = OnceCell::new();
     let _ = once_cell.set(fooer);
-    let _v = once_cell.into_inner();
+    let fooer = once_cell.into_inner();
     let count = NUM_DROPS.load(Ordering::Acquire);
     assert!(count == 0);
+    mem::drop(fooer);
+    let count = NUM_DROPS.load(Ordering::Acquire);
+    assert(count == 1);
 }