async/tcp: switch to async-fn-in-trait

Author: Dirbaio

embedded-nal-async/Cargo.toml

@@ -18,4 +18,4 @@ categories = ["embedded", "hardware-support", "no-std", "network-programming", "
 no-std-net = "0.6"
 heapless = "^0.7"
 embedded-nal = { version = "0.6.0", path = "../" }
-embedded-io = { version = "0.3.0", default-features = false, features = ["async"] }
+embedded-io = { version = "0.4.0", default-features = false, features = ["async"] }

embedded-nal-async/src/dns.rs

@@ -1,4 +1,3 @@
-use core::future::Future;
 use embedded_nal::AddrType;
 use heapless::String;
 use no_std_net::IpAddr;
@@ -17,29 +16,19 @@ pub trait Dns {
 	/// The type returned when we have an error
 	type Error: core::fmt::Debug;
 
-	/// Future for get_host_by_name
-	type GetHostByNameFuture<'m>: Future<Output = Result<IpAddr, Self::Error>>
-	where
-		Self: 'm;
-
 	/// Resolve the first ip address of a host, given its hostname and a desired
 	/// address record type to look for
-	fn get_host_by_name<'m>(
-		&'m self,
-		host: &'m str,
+	async fn get_host_by_name<'m>(
+		&self,
+		host: &str,
 		addr_type: AddrType,
-	) -> Self::GetHostByNameFuture<'m>;
-
-	/// Future for get_host_by_address
-	type GetHostByAddressFuture<'m>: Future<Output = Result<String<256>, Self::Error>>
-	where
-		Self: 'm;
+	) -> Result<IpAddr, Self::Error>;
 
 	/// Resolve the hostname of a host, given its ip address
 	///
 	/// **Note**: A fully qualified domain name (FQDN), has a maximum length of
 	/// 255 bytes [`rfc1035`]
 	///
 	/// [`rfc1035`]: https://tools.ietf.org/html/rfc1035
-	fn get_host_by_address<'m>(&'m self, addr: IpAddr) -> Self::GetHostByAddressFuture<'m>;
+	async fn get_host_by_address(&self, addr: IpAddr) -> Result<String<256>, Self::Error>;
 }

embedded-nal-async/src/lib.rs

@@ -1,7 +1,8 @@
 //! # embedded-nal-async - An async Network Abstraction Layer for Embedded Systems
 
 #![no_std]
-#![feature(generic_associated_types)]
+#![feature(async_fn_in_trait, impl_trait_projections)]
+#![allow(incomplete_features)]
 #![deny(missing_docs)]
 #![deny(unsafe_code)]
 

embedded-nal-async/src/stack/tcp.rs

@@ -1,4 +1,3 @@
-use core::future::Future;
 use no_std_net::SocketAddr;
 
 /// This trait is implemented by TCP/IP stacks. The trait allows the underlying driver to
@@ -10,29 +9,29 @@ pub trait TcpConnect {
 	type Error: embedded_io::Error;
 
 	/// Type holding state of a TCP connection. Should close the connection when dropped.
-	type Connection<'m>: embedded_io::asynch::Read<Error = Self::Error>
+	type Connection<'a>: embedded_io::asynch::Read<Error = Self::Error>
 		+ embedded_io::asynch::Write<Error = Self::Error>
 	where
-		Self: 'm;
-	/// Future returned by `connect` function.
-	type ConnectFuture<'m>: Future<Output = Result<Self::Connection<'m>, Self::Error>> + 'm
-	where
-		Self: 'm;
+		Self: 'a;
 
 	/// Connect to the given remote host and port.
 	///
 	/// Returns `Ok` if the connection was successful.
-	fn connect<'m>(&'m self, remote: SocketAddr) -> Self::ConnectFuture<'m>;
+	async fn connect<'a>(&'a self, remote: SocketAddr) -> Result<Self::Connection<'a>, Self::Error>
+	// This bound is required due to an AFIT limitaton: https://github.com/rust-lang/rust/issues/104908
+	where
+		Self: 'a;
 }
 
 impl<T: TcpConnect> TcpConnect for &T {
 	type Error = T::Error;
 
-	type Connection<'m> = T::Connection<'m> where Self: 'm;
+	type Connection<'a> = T::Connection<'a> where Self: 'a;
 
-	type ConnectFuture<'m> = T::ConnectFuture<'m> where Self: 'm;
-
-	fn connect<'m>(&'m self, remote: SocketAddr) -> Self::ConnectFuture<'m> {
-		T::connect(self, remote)
+	async fn connect<'a>(&'a self, remote: SocketAddr) -> Result<Self::Connection<'a>, Self::Error>
+	where
+		Self: 'a,
+	{
+		T::connect(self, remote).await
 	}
 }