fix more clippy warnings

src/liballoc/collections/binary_heap.rs

@@ -1269,7 +1269,7 @@ impl<'a, T: Ord> Drop for DrainSorted<'a, T> {
 
         impl<'r, 'a, T: Ord> Drop for DropGuard<'r, 'a, T> {
             fn drop(&mut self) {
-                while let Some(_) = self.0.inner.pop() {}
+                while self.0.inner.pop().is_some() {}
             }
         }
 

src/liballoc/collections/linked_list.rs

@@ -972,7 +972,7 @@ unsafe impl<#[may_dangle] T> Drop for LinkedList<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.
-                while let Some(_) = self.0.pop_front_node() {}
+                while self.0.pop_front_node().is_some() {}
             }
         }
 

src/librustc_driver/lib.rs

@@ -618,15 +618,15 @@ impl RustcDefaultCalls {
     ) -> Compilation {
         let r = matches.opt_strs("Z");
         if r.iter().any(|s| *s == "ls") {
-            match input {
-                &Input::File(ref ifile) => {
+            match *input {
+                Input::File(ref ifile) => {
                     let path = &(*ifile);
                     let mut v = Vec::new();
                     locator::list_file_metadata(&sess.target.target, path, metadata_loader, &mut v)
                         .unwrap();
                     println!("{}", String::from_utf8(v).unwrap());
                 }
-                &Input::Str { .. } => {
+                Input::Str { .. } => {
                     early_error(ErrorOutputType::default(), "cannot list metadata for stdin");
                 }
             }

src/librustc_interface/util.rs

@@ -625,8 +625,8 @@ impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
                     | ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
                     | ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
                     ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
-                    ast::TyKind::Path(_, ref path) => path.segments.iter().any(|seg| {
-                        match seg.args.as_ref().map(|generic_arg| &**generic_arg) {
+                    ast::TyKind::Path(_, ref path) => {
+                        path.segments.iter().any(|seg| match seg.args.as_deref() {
                             None => false,
                             Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
                                 data.args.iter().any(|arg| match arg {
@@ -647,8 +647,8 @@ impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
                                 any_involves_impl_trait(data.inputs.iter())
                                     || ReplaceBodyWithLoop::should_ignore_fn(&data.output)
                             }
-                        }
-                    }),
+                        })
+                    }
                     _ => false,
                 }
             }

src/librustc_metadata/rmeta/decoder/cstore_impl.rs

@@ -431,7 +431,7 @@ impl CStore {
                 ident,
                 id: ast::DUMMY_NODE_ID,
                 span,
-                attrs: attrs.iter().cloned().collect(),
+                attrs: attrs.to_vec(),
                 kind: ast::ItemKind::MacroDef(data.get_macro(id.index, sess)),
                 vis: source_map::respan(span.shrink_to_lo(), ast::VisibilityKind::Inherited),
                 tokens: None,

src/librustc_mir/transform/copy_prop.rs

@@ -246,7 +246,7 @@ impl<'tcx> Action<'tcx> {
     }
 
     fn constant(src_constant: &Constant<'tcx>) -> Option<Action<'tcx>> {
-        Some(Action::PropagateConstant((*src_constant).clone()))
+        Some(Action::PropagateConstant(*src_constant))
     }
 
     fn perform(
@@ -371,7 +371,7 @@ impl<'tcx> MutVisitor<'tcx> for ConstantPropagationVisitor<'tcx> {
             _ => return,
         }
 
-        *operand = Operand::Constant(box self.constant.clone());
+        *operand = Operand::Constant(box self.constant);
         self.uses_replaced += 1
     }
 }

src/librustc_mir_build/build/expr/as_rvalue.rs

@@ -292,7 +292,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             let of_fld = Field::new(1);
 
             let tcx = self.hir.tcx();
-            let val = tcx.mk_place_field(result_value.clone(), val_fld, ty);
+            let val = tcx.mk_place_field(result_value, val_fld, ty);
             let of = tcx.mk_place_field(result_value, of_fld, bool_ty);
 
             let err = AssertKind::Overflow(op);

src/libstd/sync/mpsc/stream.rs

@@ -329,7 +329,7 @@ impl<T> Packet<T> {
             );
             cnt != DISCONNECTED && cnt != steals
         } {
-            while let Some(_) = self.queue.pop() {
+            while self.queue.pop().is_some() {
                 steals += 1;
             }
         }