Try dropchk for AsyncProj

Author: juntyr

src/lib.rs

@@ -28,6 +28,7 @@
 #![feature(sync_unsafe_cell)]
 #![feature(never_type)]
 #![feature(layout_for_ptr)]
+#![feature(dropck_eyepatch)]
 #![feature(cfg_version)]
 #![cfg_attr(not(version("1.76.0")), feature(c_str_literals))]
 #![cfg_attr(not(version("1.76.0")), feature(ptr_from_ref))]

src/utils/async.rs

@@ -327,7 +327,7 @@ impl<'a, 'stream, T: BorrowMut<C::Completed>, C: Completion<T>> Async<'a, 'strea
             (
                 this.stream,
                 std::ptr::read(&this.value),
-                (std::ptr::read(&this.status)),
+                std::ptr::read(&this.status),
             )
         }
     }
@@ -481,6 +481,13 @@ pub struct AsyncProj<'a, 'stream, T: 'a> {
     use_callback: Option<Box<dyn FnMut() -> CudaResult<()> + 'a>>,
 }
 
+#[cfg(feature = "host")]
+unsafe impl<#[may_dangle] 'a, 'stream, T: 'a> Drop for AsyncProj<'a, 'stream, T> {
+    fn drop(&mut self) {
+        // no-op
+    }
+}
+
 #[cfg(feature = "host")]
 impl<'a, 'stream, T: 'a> AsyncProj<'a, 'stream, T> {
     #[must_use]
@@ -511,7 +518,8 @@ impl<'a, 'stream, T: 'a> AsyncProj<'a, 'stream, T> {
     /// computation out of smaller ones that have all been submitted to the
     /// same [`Stream`].
     pub(crate) unsafe fn unwrap_unchecked(self) -> T {
-        self.value
+        let (value, _use_callback) = self.unwrap_unchecked_with_use();
+        value
     }
 
     #[allow(clippy::type_complexity)]
@@ -527,7 +535,16 @@ impl<'a, 'stream, T: 'a> AsyncProj<'a, 'stream, T> {
     pub(crate) unsafe fn unwrap_unchecked_with_use(
         self,
     ) -> (T, Option<Box<dyn FnMut() -> CudaResult<()> + 'a>>) {
-        (self.value, self.use_callback)
+        let this = std::mem::ManuallyDrop::new(self);
+
+        // Safety: we destructure self into its droppable components,
+        //         value and use_callback, without dropping self itself
+        unsafe {
+            (
+                std::ptr::read(&this.value),
+                std::ptr::read(&this.use_callback),
+            )
+        }
     }
 }