tokio-xmpp: simplify examples by requiring specific TLS features

tokio-xmpp/examples/echo_server.rs

@@ -1,7 +1,6 @@
 use futures::{SinkExt, StreamExt};
 use tokio::{self, io, net::TcpSocket};
 
-#[cfg(feature = "rustls-any-backend")]
 use tokio_xmpp::rustls;
 use tokio_xmpp::{
     minidom::Element,
@@ -9,24 +8,12 @@ use tokio_xmpp::{
     xmlstream::{accept_stream, StreamHeader, Timeouts},
 };
 
-#[cfg(all(
-    feature = "rustls-any-backend",
-    not(any(feature = "aws_lc_rs", feature = "ring"))
-))]
-compile_error!("using rustls (e.g. via the ktls feature) needs an enabled rustls backend feature (either aws_lc_rs or ring).");
-
 #[tokio::main]
 async fn main() -> Result<(), io::Error> {
-    #[cfg(all(feature = "aws_lc_rs", not(feature = "ring")))]
     rustls::crypto::aws_lc_rs::default_provider()
         .install_default()
         .expect("failed to install rustls crypto provider");
 
-    #[cfg(all(feature = "ring"))]
-    rustls::crypto::ring::default_provider()
-        .install_default()
-        .expect("failed to install rustls crypto provider");
-
     // TCP socket
     let address = "127.0.0.1:5222".parse().unwrap();
     let socket = TcpSocket::new_v4()?;