Simplifications from clippy

Author: Philippe-Cholet

src/lib.rs

@@ -2318,10 +2318,10 @@ pub trait Itertools: Iterator {
                 // estimate lower bound of capacity needed
                 let (lower, _) = self.size_hint();
                 let mut result = String::with_capacity(sep.len() * lower);
-                write!(&mut result, "{}", first_elt).unwrap();
+                write!(&mut result, "{first_elt}").unwrap();
                 self.for_each(|elt| {
                     result.push_str(sep);
-                    write!(&mut result, "{}", elt).unwrap();
+                    write!(&mut result, "{elt}").unwrap();
                 });
                 result
             }
@@ -4520,13 +4520,7 @@ where
                     (Some(a), Some(b)) => a == b,
                     _ => false,
                 };
-                assert!(
-                    equal,
-                    "Failed assertion {a:?} == {b:?} for iteration {i}",
-                    i = i,
-                    a = a,
-                    b = b
-                );
+                assert!(equal, "Failed assertion {a:?} == {b:?} for iteration {i}",);
                 i += 1;
             }
         }

src/process_results_impl.rs

@@ -62,8 +62,7 @@ where
 
 impl<'a, I, T, E> DoubleEndedIterator for ProcessResults<'a, I, E>
 where
-    I: Iterator<Item = Result<T, E>>,
-    I: DoubleEndedIterator,
+    I: DoubleEndedIterator<Item = Result<T, E>>,
 {
     fn next_back(&mut self) -> Option<Self::Item> {
         let item = self.iter.next_back();

src/repeatn.rs

@@ -34,7 +34,7 @@ where
     fn next(&mut self) -> Option<Self::Item> {
         if self.n > 1 {
             self.n -= 1;
-            self.elt.as_ref().cloned()
+            self.elt.clone()
         } else {
             self.n = 0;
             self.elt.take()