Fix further clippy lints

... and explicitly annotate crates as well.

futures/src/lib.rs

@@ -4,13 +4,19 @@
 #![doc(
     html_logo_url = "https://raw.githubusercontent.com/iced-rs/iced/9ab6923e943f784985e9ef9ca28b10278297225d/docs/logo.svg"
 )]
-#![deny(missing_docs)]
-#![deny(missing_debug_implementations)]
-#![deny(unused_results)]
-#![forbid(unsafe_code)]
-#![forbid(rust_2018_idioms)]
+#![deny(
+    missing_debug_implementations,
+    missing_docs,
+    unused_results,
+    clippy::extra_unused_lifetimes,
+    clippy::from_over_into,
+    clippy::needless_borrow,
+    clippy::new_without_default,
+    clippy::useless_conversion
+)]
+#![forbid(unsafe_code, rust_2018_idioms)]
+#![allow(clippy::inherent_to_string, clippy::type_complexity)]
 #![cfg_attr(docsrs, feature(doc_cfg))]
-
 pub use futures;
 
 mod command;

futures/src/runtime.rs

@@ -66,8 +66,6 @@ where
 
         let future = future.then(|message| async move {
             let _ = sender.send(message).await;
-
-            ()
         });
 
         self.executor.spawn(future);

futures/src/subscription/tracker.rs

@@ -156,3 +156,13 @@ where
             });
     }
 }
+
+impl<Hasher, Event> Default for Tracker<Hasher, Event>
+where
+    Hasher: std::hash::Hasher + Default,
+    Event: 'static + Send + Clone,
+{
+    fn default() -> Self {
+        Self::new()
+    }
+}