chore(tcp): remove async_std support

transports/tcp/Cargo.toml

@@ -23,6 +23,7 @@ tracing = { workspace = true }
 
 [features]
 tokio = ["dep:tokio", "if-watch/tokio"]
+# async-io feature is deprecated and will be removed in a future release
 async-io = ["dep:async-io", "if-watch/smol"]
 
 [dev-dependencies]

transports/tcp/src/lib.rs

@@ -25,6 +25,11 @@
 //! This crate provides a [`async_io::Transport`] and [`tokio::Transport`], depending on
 //! the enabled features, which implement the [`libp2p_core::Transport`] trait for use as a
 //! transport with `libp2p-core` or `libp2p-swarm`.
+//!
+//! This crate provides a [`async_io::Transport`] (deprecated) and [`tokio::Transport`],
+//! which implement the [`libp2p_core::Transport`] trait for use as a
+//! transport with `libp2p-core` or `libp2p-swarm`.
+//!
 
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 

transports/tcp/src/provider/async_io.rs

@@ -54,8 +54,16 @@ use super::{Incoming, Provider};
 /// println!("Listening on {addr}");
 /// # }
 /// ```
+#[deprecated(
+    since = "0.43.0",
+    note = "async_std has been discontinued. Please use the tokio feature instead."
+)]
 pub type Transport = crate::Transport<Tcp>;
 
+#[deprecated(
+    since = "0.43.0",
+    note = "async_std has been discontinued. Please use the tokio feature instead."
+)]
 #[derive(Copy, Clone)]
 #[doc(hidden)]
 pub enum Tcp {}