Add #[track_caller] for better panic messages for fallible locks using lock_api.

lock_api/src/mutex.rs

@@ -219,6 +219,7 @@ impl<R: RawMutex, T: ?Sized> Mutex<R, T> {
     /// Attempts to lock a mutex in the thread which already holds the lock will
     /// result in a deadlock.
     #[inline]
+    #[track_caller]
     pub fn lock(&self) -> MutexGuard<'_, R, T> {
         self.raw.lock();
         // SAFETY: The lock is held, as required.
@@ -326,6 +327,7 @@ impl<R: RawMutex, T: ?Sized> Mutex<R, T> {
     /// and the resulting mutex guard has no lifetime requirements.
     #[cfg(feature = "arc_lock")]
     #[inline]
+    #[track_caller]
     pub fn lock_arc(self: &Arc<Self>) -> ArcMutexGuard<R, T> {
         self.raw.lock();
         // SAFETY: the locking guarantee is upheld

lock_api/src/remutex.rs

@@ -322,6 +322,7 @@ impl<R: RawMutex, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> {
     /// returned to allow scoped unlock of the lock. When the guard goes out of
     /// scope, the mutex will be unlocked.
     #[inline]
+    #[track_caller]
     pub fn lock(&self) -> ReentrantMutexGuard<'_, R, G, T> {
         self.raw.lock();
         // SAFETY: The lock is held, as required.
@@ -436,6 +437,7 @@ impl<R: RawMutex, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> {
     /// `Arc` and the resulting mutex guard has no lifetime requirements.
     #[cfg(feature = "arc_lock")]
     #[inline]
+    #[track_caller]
     pub fn lock_arc(self: &Arc<Self>) -> ArcReentrantMutexGuard<R, G, T> {
         self.raw.lock();
         // SAFETY: locking guarantee is upheld