chore: add more `Debug` impls to `embassy-sync`, particularly on `OnceLock`

All tests green

1 files changed, 10 insertions, 0 deletions

diff --git a/embassy-sync/src/once_lock.rs b/embassy-sync/src/once_lock.rs
index 1e848685a..73edfea9a 100644
--- a/embassy-sync/src/once_lock.rs
+++ b/embassy-sync/src/once_lock.rs
@@ -1,6 +1,7 @@
 //! Synchronization primitive for initializing a value once, allowing others to await a reference to the value.
 
 use core::cell::Cell;
+use core::fmt::{Debug, Formatter};
 use core::future::{poll_fn, Future};
 use core::mem::MaybeUninit;
 use core::sync::atomic::{AtomicBool, Ordering};
@@ -42,6 +43,15 @@ pub struct OnceLock<T> {
     data: Cell<MaybeUninit<T>>,
 }
 
+impl<T> Debug for OnceLock<T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        f.debug_struct("OnceLock")
+            .field("init", &self.init)
+            .field("data", &"Cell<MaybeUninit<{unprintable}>>")
+            .finish()
+    }
+}
+
 unsafe impl<T> Sync for OnceLock<T> where T: Sync {}
 
 impl<T> OnceLock<T> {