Remove ability to create AlreadyCancled instance

Author: Sh3Rm4n

CHANGELOG.md

@@ -46,6 +46,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   which resulted into the situtation, that BSD 0-clause was not affectivly
   0-clause as MIT conditions had to be met anyways. (🧂 IANAL). ([#309])
 - Renamed `Serial::raw_read` to `Serial::read_data_register`. ([#281])
+- Timer error type `AlreadyCancled` is no longer public constructable. ([#281])
 - Move ADC from a macro to a generic implementation, meaning that
   it is possible to obtain an ADC instance via `Adc::new` instead of
   `Adc::adc1`. ([#281])

src/timer.rs

@@ -294,7 +294,7 @@ where
 /// Error if a [`Cancel`]-ble [`Timer`] was cancled already or never been started.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
-pub struct AlreadyCancled;
+pub struct AlreadyCancled(pub(crate) ());
 
 impl<TIM> Cancel for Timer<TIM>
 where
@@ -304,7 +304,7 @@ where
     fn cancel(&mut self) -> Result<(), Self::Error> {
         // If timer is already stopped.
         if !self.tim.is_cr1_cen_set() {
-            return Err(AlreadyCancled);
+            return Err(AlreadyCancled(()));
         }
         self.stop();
         Ok(())