derive Debug for some structs

This facilitates e.g. `my_task::spawn(my_signal_reader).unwrap();`

rtic-common/src/waker_registration.rs

@@ -4,6 +4,7 @@ use core::cell::UnsafeCell;
 use core::task::Waker;
 
 /// A critical section based waker handler.
+#[derive(Debug)]
 pub struct CriticalSectionWakerRegistration {
     waker: UnsafeCell<Option<Waker>>,
 }

rtic-sync/src/signal.rs

@@ -5,13 +5,14 @@ use rtic_common::waker_registration::CriticalSectionWakerRegistration;
 
 /// Basically an Option but for indicating
 /// whether the store has been set or not
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 enum Store<T> {
     Set(T),
     Unset,
 }
 
 /// A "latest only" value store with unlimited writers and async waiting.
+#[derive(Debug)]
 pub struct Signal<T: Copy> {
     waker: CriticalSectionWakerRegistration,
     store: UnsafeCell<Store<T>>,
@@ -42,7 +43,7 @@ impl<T: Copy> Signal<T> {
 }
 
 /// Facilitates the writing of values to a Signal.
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct SignalWriter<'a, T: Copy> {
     parent: &'a Signal<T>,
 }
@@ -70,6 +71,7 @@ impl<'a, T: Copy> SignalWriter<'a, T> {
 }
 
 /// Facilitates the async reading of values from the Signal.
+#[derive(Debug)]
 pub struct SignalReader<'a, T: Copy> {
     parent: &'a Signal<T>,
 }