Made NamedMutex !Send

Author: gurry

crates/cargo-wdk/src/actions/build/package_task.rs

@@ -556,10 +556,14 @@ impl<'a> PackageTask<'a> {
 /// An RAII wrapper over a Win API named mutex
 struct NamedMutex {
     handle: HANDLE,
+    // `ReleaseMutex` requires that it is called
+    // only by threads that own the mutex handle.
+    // Being `!Send` ensures that's always the case.
+    _not_send: std::marker::PhantomData<*const ()>,
 }
 
 impl NamedMutex {
-    /// Acquire named mutex
+    /// Acquires named mutex
     pub fn acquire(name: &CStr) -> Result<Self, WinError> {
         fn get_last_error() -> WinError {
             // SAFETY: We have to just assume this function is safe to call
@@ -593,7 +597,7 @@ impl Drop for NamedMutex {
         // because this type itself created it and it
         // was never exposed outside
         unsafe {
-            // This Cannot fail as the calling thread is guaranteed
+            // This cannot fail as the calling thread is guaranteed
             // to own the handle since we do not implement Send
             let _ = ReleaseMutex(self.handle);
 

crates/cargo-wdk/tests/test_utils/mod.rs

@@ -191,10 +191,14 @@ where
 /// An RAII wrapper over a Win API named mutex
 pub struct NamedMutex {
     handle: HANDLE,
+    // `ReleaseMutex` requires that it is called
+    // only by threads that own the mutex handle.
+    // Being `!Send` ensures that's always the case.
+    _not_send: std::marker::PhantomData<*const ()>,
 }
 
 impl NamedMutex {
-    /// Acquire named mutex
+    /// Acquires named mutex
     pub fn acquire(name: &CStr) -> Result<Self, WinError> {
         fn get_last_error() -> WinError {
             // SAFETY: We have to just assume this function is safe to call
@@ -228,7 +232,7 @@ impl Drop for NamedMutex {
         // because this type itself created it and it
         // was never exposed outside
         unsafe {
-            // This Cannot fail as the calling thread is guaranteed
+            // This cannot fail as the calling thread is guaranteed
             // to own the handle since we do not implement Send
             let _ = ReleaseMutex(self.handle);