assert that the shard count is not 1 (#273)

* assert that the shard count is not 1

* lint

Author: xacrimon

src/lib.rs

@@ -270,7 +270,7 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> DashMap<K, V, S> {
         hasher: S,
         shard_amount: usize,
     ) -> Self {
-        assert!(shard_amount > 0);
+        assert!(shard_amount > 1);
         assert!(shard_amount.is_power_of_two());
 
         let shift = util::ptr_size_bits() - ncb(shard_amount);

src/mapref/entry.rs

@@ -159,9 +159,7 @@ impl<'a, K: Eq + Hash, V, S: BuildHasher> VacantEntry<'a, K, V, S> {
 
             let kptr: *const K = k;
             let vptr: *mut V = v.as_ptr();
-            let r = OccupiedEntry::new(self.shard, self.key, (kptr, vptr));
-
-            r
+            OccupiedEntry::new(self.shard, self.key, (kptr, vptr))
         }
     }