Make serial::Serial sealed (#274)

crates/prelude/CHANGELOG.md

@@ -86,4 +86,4 @@
 
 ## 0.1.0
 
-<!-- Increment to skip CHANGELOG.md test: 14 -->
+<!-- Increment to skip CHANGELOG.md test: 15 -->

crates/prelude/src/serial.rs

@@ -18,6 +18,8 @@ use alloc::boxed::Box;
 use core::cell::Cell;
 use core::fmt::Debug;
 
+use sealed::sealed;
+
 use crate::scheduling;
 
 /// Serial events to be notified.
@@ -31,6 +33,10 @@ pub enum Event {
 }
 
 /// Provides high-level serial API from low-level API.
+///
+/// This trait should only be implemented by the prelude and is thus sealed. Its purpose is to
+/// provide a unique interface to the different serials.
+#[sealed(pub(crate))]
 pub trait Serial {
     type Error: Clone + Debug;
 

crates/prelude/src/uart.rs

@@ -14,9 +14,10 @@
 
 //! Provides API for UART.
 
+use sealed::sealed;
 use wasefire_applet_api::uart as api;
 
-use crate::serial::{Event, Serial};
+use crate::serial::Event;
 
 /// UART error.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
@@ -31,7 +32,8 @@ pub fn count() -> usize {
 /// Implements the [`Serial`] interface for UART.
 pub struct Uart(pub usize);
 
-impl Serial for Uart {
+#[sealed]
+impl crate::serial::Serial for Uart {
     type Error = Error;
 
     fn read(&self, buffer: &mut [u8]) -> Result<usize, Error> {

crates/prelude/src/usb/serial.rs

@@ -14,15 +14,17 @@
 
 //! Provides API for USB serial.
 
+use sealed::sealed;
 use wasefire_applet_api::usb::serial as api;
 
-use crate::serial::{Event, Serial};
+use crate::serial::Event;
 use crate::usb::{convert, Error};
 
 /// Implements the [`Serial`] interface for the USB serial.
 pub struct UsbSerial;
 
-impl Serial for UsbSerial {
+#[sealed]
+impl crate::serial::Serial for UsbSerial {
     type Error = Error;
 
     fn read(&self, buffer: &mut [u8]) -> Result<usize, Error> {