Merge pull request #690 from AstroHQ/dispatch_soundness_fix

fix(dispatch2): Add `'static` bound to `exec_async`

crates/dispatch2/CHANGELOG.md

@@ -59,6 +59,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Fixed
 - **BREAKING**: Use `extern "C-unwind"` instead of `extern "C"` in certain functions that required that.
 - **BREAKING**: Use `isize` instead of `usize` in certain functions where that is more correct.
+- **BREAKING**: An `F: 'static` bound was added to the following methods to make
+                sure any referenced values passed to them are borrowed for long
+                enough since they perform their `work` asynchronously (#689):
+  - `Group::exec_async`
+  - `Queue::exec_async`
+  - `Queue::barrier_async`
+  - `Queue::barrier_async_and_wait`
 
 
 ## 0.1.0 - 2022-10-02

crates/dispatch2/src/group.rs

@@ -38,7 +38,9 @@ impl Group {
     /// Submit a function to a [Queue] and associates it with the [Group].
     pub fn exec_async<F>(&self, queue: &Queue, work: F)
     where
-        F: Send + FnOnce(),
+        // We need `'static` to make sure any referenced values are borrowed for
+        // long enough since `work` will be performed asynchronously.
+        F: Send + FnOnce() + 'static,
     {
         let work_boxed = Box::into_raw(Box::new(work)).cast::<c_void>();
 

crates/dispatch2/src/queue.rs

@@ -226,7 +226,9 @@ impl Queue {
     /// Submit a function for asynchronous execution on the [Queue].
     pub fn exec_async<F>(&self, work: F)
     where
-        F: Send + FnOnce(),
+        // We need `'static` to make sure any referenced values are borrowed for
+        // long enough since `work` will be performed asynchronously.
+        F: Send + FnOnce() + 'static,
     {
         let work_boxed = Box::into_raw(Box::new(work)).cast();
 
@@ -254,7 +256,9 @@ impl Queue {
     /// Enqueue a barrier function for asynchronous execution on the [Queue] and return immediately.
     pub fn barrier_async<F>(&self, work: F)
     where
-        F: Send + FnOnce(),
+        // We need `'static` to make sure any referenced values are borrowed for
+        // long enough since `work` will be performed asynchronously.
+        F: Send + FnOnce() + 'static,
     {
         let work_boxed = Box::into_raw(Box::new(work)).cast();
 
@@ -276,7 +280,9 @@ impl Queue {
     /// Submit a function for synchronous execution and mark the function as a barrier for subsequent concurrent tasks.
     pub fn barrier_async_and_wait<F>(&self, work: F)
     where
-        F: Send + FnOnce(),
+        // We need `'static` to make sure any referenced values are borrowed for
+        // long enough since `work` will be performed asynchronously.
+        F: Send + FnOnce() + 'static,
     {
         let work_boxed = Box::into_raw(Box::new(work)).cast();