Cleanup default_runtime method

quinn/src/runtime.rs

@@ -70,7 +70,8 @@ pub trait AsyncUdpSocket: Send + Sync + Debug + 'static {
 ///
 /// If `runtime-tokio` is enabled and this function is called from within a Tokio runtime context,
 /// then `TokioRuntime` is returned. Otherwise, if `runtime-async-std` is enabled, `AsyncStdRuntime`
-/// is returned. Otherwise, `None` is returned.
+/// is returned. Otherwise, if `runtime-smol` is enabled, `SmolRuntime` is returned.
+/// Otherwise, `None` is returned.
 pub fn default_runtime() -> Option<Arc<dyn Runtime>> {
     #[cfg(feature = "runtime-tokio")]
     {
@@ -89,7 +90,6 @@ pub fn default_runtime() -> Option<Arc<dyn Runtime>> {
         return Some(Arc::new(SmolRuntime));
     }
 
-    #[cfg(not(feature = "runtime-async-std"))]
     None
 }