Fix beta Clippy warnings

clippy 0.1.83 (88c1c3c1102 2024-10-18)

src/common/deque.rs

@@ -70,7 +70,7 @@ impl<T> Drop for Deque<T> {
     fn drop(&mut self) {
         struct DropGuard<'a, T>(&'a mut Deque<T>);
 
-        impl<'a, T> Drop for DropGuard<'a, T> {
+        impl<T> Drop for DropGuard<'_, T> {
             fn drop(&mut self) {
                 // Continue the same loop we do below. This only runs when a destructor has
                 // panicked. If another one panics this will abort.

src/sync/base_cache.rs

@@ -219,6 +219,10 @@ where
     }
 }
 
+// Clippy beta 0.1.83 (f41c7ed9889 2024-10-31) warns about unused lifetimes on 'a.
+// This seems a false positive. The lifetimes are used in the trait bounds.
+// https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
+#[allow(clippy::extra_unused_lifetimes)]
 impl<'a, K, V, S> BaseCache<K, V, S>
 where
     K: 'a + Eq + Hash,
@@ -620,6 +624,10 @@ impl<K, V, S> Inner<K, V, S> {
     }
 }
 
+// Clippy beta 0.1.83 (f41c7ed9889 2024-10-31) warns about unused lifetimes on 'a.
+// This seems a false positive. The lifetimes are used in the trait bounds.
+// https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
+#[allow(clippy::extra_unused_lifetimes)]
 impl<'a, K, V, S> Inner<K, V, S>
 where
     K: 'a + Eq + Hash,

src/sync/cache.rs

@@ -493,6 +493,10 @@ where
     }
 }
 
+// Clippy beta 0.1.83 (f41c7ed9889 2024-10-31) warns about unused lifetimes on 'a.
+// This seems a false positive. The lifetimes are used in the trait bounds.
+// https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
+#[allow(clippy::extra_unused_lifetimes)]
 impl<'a, K, V, S> Cache<K, V, S>
 where
     K: 'a + Eq + Hash,

src/sync/iter.rs

@@ -39,15 +39,23 @@ where
     }
 }
 
-unsafe impl<'a, 'i, K, V, S> Send for Iter<'i, K, V, S>
+// Clippy beta 0.1.83 (f41c7ed9889 2024-10-31) warns about unused lifetimes on 'a.
+// This seems a false positive. The lifetimes are used in the trait bounds.
+// https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
+#[allow(clippy::extra_unused_lifetimes)]
+unsafe impl<'a, K, V, S> Send for Iter<'_, K, V, S>
 where
     K: 'a + Eq + Hash + Send,
     V: 'a + Send,
     S: 'a + BuildHasher + Clone,
 {
 }
 
-unsafe impl<'a, 'i, K, V, S> Sync for Iter<'i, K, V, S>
+// Clippy beta 0.1.83 (f41c7ed9889 2024-10-31) warns about unused lifetimes on 'a.
+// This seems a false positive. The lifetimes are used in the trait bounds.
+// https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
+#[allow(clippy::extra_unused_lifetimes)]
+unsafe impl<'a, K, V, S> Sync for Iter<'_, K, V, S>
 where
     K: 'a + Eq + Hash + Sync,
     V: 'a + Sync,

src/sync/mapref.rs

@@ -8,7 +8,7 @@ type DashMapRef<'a, K, V> =
 
 pub struct EntryRef<'a, K, V>(DashMapRef<'a, K, V>);
 
-unsafe impl<'a, K, V> Sync for EntryRef<'a, K, V>
+unsafe impl<K, V> Sync for EntryRef<'_, K, V>
 where
     K: Eq + Hash + Send + Sync,
     V: Send + Sync,
@@ -36,7 +36,7 @@ where
     }
 }
 
-impl<'a, K, V> std::ops::Deref for EntryRef<'a, K, V>
+impl<K, V> std::ops::Deref for EntryRef<'_, K, V>
 where
     K: Eq + Hash,
 {

src/unsync/cache.rs

@@ -427,7 +427,8 @@ where
     /// Like the `invalidate` method, this method does not clear the historic
     /// popularity estimator of keys so that it retains the client activities of
     /// trying to retrieve an item.
-
+    // -----------------------------------------------------------------------
+    // (The followings are not doc comments)
     // We need this #[allow(...)] to avoid a false Clippy warning about needless
     // collect to create keys_to_invalidate.
     // clippy 0.1.52 (9a1dfd2dc5c 2021-04-30) in Rust 1.52.0-beta.7