From 2c1d0f75c0e432fcb3123c09cfd374ad390a8ebe Mon Sep 17 00:00:00 2001
From: katelyn martin <kate@buoyant.io>
Date: Mon, 24 Feb 2025 00:00:00 +0000
Subject: [PATCH] chore(tls): remove redundant i/o bounds

this commit removes a redundant set of trait bounds from
`linkerd_tls::Client<L, C>`'s `tower::Service<T>` implementation.

this client type is generic over a `C`-typed `MakeConnection`. this
trait is effectively an alias for particular services, and already by
definition is prerequisite upon `Connection` responses that are
an asynchronous reader/writer.

see the definition of the trait, here:

```rust
// linkerd/stack/src/connect.rs

pub trait MakeConnection<T> {
    /// An I/O type that represents a connection to the remote endpoint.
    type Connection: AsyncRead + AsyncWrite;

    /// Metadata associated with the established connection.
    type Metadata;

    type Error: Into<Error>;

    type Future: Future<Output = Result<(Self::Connection, Self::Metadata), Self::Error>>;

    /// Determines whether the connector is ready to establish a connection.
    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>>;

    /// Establishes a connection.
    fn connect(&mut self, t: T) -> Self::Future;

    // contd...
}
```

thus, we can remove these bounds from the tls client. the connection is
already, by virtue of `C: MakeConnection`, an `AsyncRead + AsyncWrite`
type.

see https://github.com/linkerd/linkerd2/issues/8733.

Signed-off-by: katelyn martin <kate@buoyant.io>
---
 linkerd/tls/src/client.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linkerd/tls/src/client.rs b/linkerd/tls/src/client.rs
index ca07551208..642db8a618 100644
--- a/linkerd/tls/src/client.rs
+++ b/linkerd/tls/src/client.rs
@@ -102,7 +102,7 @@ where
     T: Param<ConditionalClientTls>,
     L: NewService<ClientTls, Service = H>,
     C: MakeConnection<T, Error = io::Error>,
-    C::Connection: io::AsyncRead + io::AsyncWrite + Send + Unpin,
+    C::Connection: Send + Unpin,
     C::Metadata: Send + Unpin,
     C::Future: Send + 'static,
     H: Service<C::Connection, Response = (I, Option<NegotiatedProtocol>), Error = io::Error>