Remove Serial::split

CHANGELOG.md

@@ -24,6 +24,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   - Add `impl From<Toggle> for Switch` to reduce churn.
 - Fix undefined behavior in SPI implementation ([#346])
   - Add `num_traits::PrimInt` bounds to `Word`
+- Remove `Serial::split`, which possibly creates two mutable references two
+  one Serial instance, which could've caused UB. The use case of this function
+  was hard to find out anyway.
 
 ### Added
 

src/dma.rs

@@ -571,8 +571,6 @@ dma!( 2: { 1,2,3,4,5 } );
 /// Marker trait mapping DMA targets to their channels
 pub trait OnChannel<C: Channel>: Target + crate::private::Sealed {}
 
-use crate::serial::{RxPin, TxPin};
-
 macro_rules! on_channel {
     (
         $(
@@ -581,10 +579,6 @@ macro_rules! on_channel {
     ) => {
         $(
             $(
-                impl<Pin> crate::private::Sealed for serial::Tx<$USART, Pin> {}
-                impl<Pin> OnChannel<$dma::$TxChannel> for serial::Tx<$USART, Pin> where Pin: TxPin<$USART> {}
-                impl<Pin> crate::private::Sealed for serial::Rx<$USART, Pin> {}
-                impl<Pin> OnChannel<$dma::$RxChannel> for serial::Rx<$USART, Pin> where Pin: RxPin<$USART> {}
                 impl<Tx, Rx> crate::private::Sealed for serial::Serial<$USART, (Tx, Rx)> {}
                 impl<Tx, Rx> OnChannel<$dma::$TxChannel> for serial::Serial<$USART, (Tx, Rx)> {}
                 impl<Tx, Rx> OnChannel<$dma::$RxChannel> for serial::Serial<$USART, (Tx, Rx)> {}