Remove some unnecessary .into() calls

Author: estebank

alloc/src/rc.rs

@@ -1789,7 +1789,7 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
     /// let x: Rc<&str> = Rc::new("Hello, world!");
     /// {
     ///     let s = String::from("Oh, no!");
-    ///     let mut y: Rc<&str> = x.clone().into();
+    ///     let mut y: Rc<&str> = x.clone();
     ///     unsafe {
     ///         // this is Undefined Behavior, because x's inner type
     ///         // is &'long str, not &'short str

alloc/src/sync.rs

@@ -2468,7 +2468,7 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
     /// let x: Arc<&str> = Arc::new("Hello, world!");
     /// {
     ///     let s = String::from("Oh, no!");
-    ///     let mut y: Arc<&str> = x.clone().into();
+    ///     let mut y: Arc<&str> = x.clone();
     ///     unsafe {
     ///         // this is Undefined Behavior, because x's inner type
     ///         // is &'long str, not &'short str

std/src/thread/mod.rs

@@ -502,7 +502,7 @@ impl Builder {
 
         let id = ThreadId::new();
         let my_thread = match name {
-            Some(name) => Thread::new(id, name.into()),
+            Some(name) => Thread::new(id, name),
             None => Thread::new_unnamed(id),
         };