Auto merge of #7224 - Manishearth:clippy, r=Ms2ger

Integrate clippy into Servo; cleanup some of script

The integration is off by default for now. You can try it out with `./mach build --features "script/plugins/clippy"`.

We're using a branch of clippy with some of the lints changed to Allow, either because they don't apply to us, or because they're noisy and dwarf other warnings (but still should be fixed)

After going through the rest of Servo's warnings I'll figure out which lints we should be keeping.

There's a cargo bug with optional deps that makes it hard for this to work with Cargo.lock -- so this PR contains no changes to lockfiles (and running the build with clippy on may dirty the lockfile, though it gets fixed later)

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15 files changed, 67 insertions, 104 deletions

diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 72855380540..6ca62f181e3 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -264,7 +264,7 @@ impl LayoutDataRef {
 
     /// Borrows the layout data immutably. This function is *not* thread-safe.
     #[inline]
-    pub fn borrow<'a>(&'a self) -> Ref<'a, Option<LayoutData>> {
+    pub fn borrow(&self) -> Ref<Option<LayoutData>> {
         debug_assert!(task_state::get().is_layout());
         self.data_cell.borrow()
     }
@@ -275,7 +275,7 @@ impl LayoutDataRef {
     /// prevent CSS selector matching from mutably accessing nodes it's not supposed to and racing
     /// on it. This has already resulted in one bug!
     #[inline]
-    pub fn borrow_mut<'a>(&'a self) -> RefMut<'a, Option<LayoutData>> {
+    pub fn borrow_mut(&self) -> RefMut<Option<LayoutData>> {
         debug_assert!(task_state::get().is_layout());
         self.data_cell.borrow_mut()
     }
@@ -908,7 +908,7 @@ impl<'a> NodeHelpers for &'a Node {
         // Step 1.
         match parse_author_origin_selector_list_from_str(&selectors) {
             // Step 2.
-            Err(()) => return Err(Syntax),
+            Err(()) => Err(Syntax),
             // Step 3.
             Ok(ref selectors) => {
                 let root = self.ancestors().last();
@@ -1326,7 +1326,7 @@ impl Iterator for FollowingNodeIterator {
             }
         }
         self.current = None;
-        return None
+        None
     }
 }
 
@@ -1372,7 +1372,7 @@ impl Iterator for PrecedingNodeIterator {
         }
 
         self.current = None;
-        return None
+        None
     }
 }
 
@@ -1663,7 +1663,7 @@ impl Node {
         Node::insert(node, parent, reference_child, SuppressObserver::Unsuppressed);
 
         // Step 6.
-        return Ok(Root::from_ref(node))
+        Ok(Root::from_ref(node))
     }
 
     // https://dom.spec.whatwg.org/#concept-node-insert
@@ -2088,24 +2088,13 @@ impl<'a> NodeMethods for &'a Node {
 
     // https://dom.spec.whatwg.org/#dom-node-nodevalue
     fn GetNodeValue(self) -> Option<DOMString> {
-        match self.type_id {
-            NodeTypeId::CharacterData(..) => {
-                let chardata: &CharacterData = CharacterDataCast::to_ref(self).unwrap();
-                Some(chardata.Data())
-            }
-            _ => {
-                None
-            }
-        }
+        CharacterDataCast::to_ref(self).map(|c| c.Data())
     }
 
     // https://dom.spec.whatwg.org/#dom-node-nodevalue
     fn SetNodeValue(self, val: Option<DOMString>) {
-        match self.type_id {
-            NodeTypeId::CharacterData(..) => {
-                self.SetTextContent(val)
-            }
-            _ => {}
+        if let NodeTypeId::CharacterData(..) = self.type_id {
+            self.SetTextContent(val)
         }
     }
 
@@ -2565,7 +2554,7 @@ pub fn window_from_node<T: NodeBase + Reflectable>(derived: &T) -> Root<Window>
 }
 
 impl<'a> VirtualMethods for &'a Node {
-    fn super_type<'b>(&'b self) -> Option<&'b VirtualMethods> {
+    fn super_type(&self) -> Option<&VirtualMethods> {
         let eventtarget: &&EventTarget = EventTargetCast::from_borrowed_ref(self);
         Some(eventtarget as &VirtualMethods)
     }
diff --git a/components/script/dom/nodeiterator.rs b/components/script/dom/nodeiterator.rs
index 7e641c83cfd..0958bfca992 100644
--- a/components/script/dom/nodeiterator.rs
+++ b/components/script/dom/nodeiterator.rs
@@ -138,7 +138,7 @@ impl<'a> NodeIteratorMethods for &'a NodeIterator {
             }
         }
 
-        return Ok(None);
+        Ok(None)
     }
 
     // https://dom.spec.whatwg.org/#dom-nodeiterator-previousnode
@@ -183,7 +183,7 @@ impl<'a> NodeIteratorMethods for &'a NodeIterator {
             }
         }
 
-        return Ok(None);
+        Ok(None)
     }
 
     // https://dom.spec.whatwg.org/#dom-nodeiterator-detach
diff --git a/components/script/dom/range.rs b/components/script/dom/range.rs
index b67ce2d60c8..78af618eff5 100644
--- a/components/script/dom/range.rs
+++ b/components/script/dom/range.rs
@@ -122,7 +122,7 @@ impl Range {
             return Err(HierarchyRequest);
         }
 
-        return Ok((first_contained_child, last_contained_child, contained_children));
+        Ok((first_contained_child, last_contained_child, contained_children))
     }
 }
 
@@ -338,17 +338,11 @@ impl<'a> RangeMethods for &'a Range {
         let end = &inner.end;
         let end_node = end.node();
         let end_offset = end.offset;
-        match (bp_position(parent.r(), offset + 1, start_node.r(), start_offset).unwrap(),
-               bp_position(parent.r(), offset, end_node.r(), end_offset).unwrap()) {
-            (Ordering::Greater, Ordering::Less) => {
-                // Step 5.
-                true
-            },
-            _ => {
-                // Step 6.
-                false
-            }
-        }
+        // Step 5.
+        Ordering::Greater == bp_position(parent.r(), offset + 1,
+                                         start_node.r(), start_offset).unwrap() &&
+        Ordering::Less == bp_position(parent.r(), offset,
+                                      end_node.r(), end_offset).unwrap()
     }
 
     // https://dom.spec.whatwg.org/#dom-range-clonecontents
diff --git a/components/script/dom/servohtmlparser.rs b/components/script/dom/servohtmlparser.rs
index e979e3f6610..b9ccd50632f 100644
--- a/components/script/dom/servohtmlparser.rs
+++ b/components/script/dom/servohtmlparser.rs
@@ -268,7 +268,7 @@ impl ServoHTMLParser {
     }
 
     #[inline]
-    pub fn tokenizer<'a>(&'a self) -> &'a DOMRefCell<Tokenizer> {
+    pub fn tokenizer(&self) -> &DOMRefCell<Tokenizer> {
         &self.tokenizer
     }
 }
diff --git a/components/script/dom/textencoder.rs b/components/script/dom/textencoder.rs
index 29a715a8ed1..1b76de05d0d 100644
--- a/components/script/dom/textencoder.rs
+++ b/components/script/dom/textencoder.rs
@@ -65,7 +65,7 @@ impl TextEncoder {
             }
             _ => {
                 debug!("Encoding Not UTF");
-                return Err(Range("The encoding must be utf-8, utf-16le, or utf-16be.".to_owned()))
+                Err(Range("The encoding must be utf-8, utf-16le, or utf-16be.".to_owned()))
             }
         }
     }
@@ -87,7 +87,7 @@ impl<'a> TextEncoderMethods for &'a TextEncoder {
 
             let js_object_data: *mut uint8_t = JS_GetUint8ArrayData(js_object, ptr::null());
             ptr::copy_nonoverlapping(encoded.as_ptr(), js_object_data, length as usize);
-            return js_object;
+            js_object
         }
     }
 }
diff --git a/components/script/dom/treewalker.rs b/components/script/dom/treewalker.rs
index b859a2f0277..b8271909505 100644
--- a/components/script/dom/treewalker.rs
+++ b/components/script/dom/treewalker.rs
@@ -104,12 +104,9 @@ impl<'a> TreeWalkerMethods for &'a TreeWalker {
                     node = n;
                     // "2. If node is not null and filtering node returns FILTER_ACCEPT,
                     //     then set the currentNode attribute to node, return node."
-                    match try!(self.accept_node(node.r())) {
-                        NodeFilterConstants::FILTER_ACCEPT => {
-                            self.current_node.set(JS::from_rooted(&node));
-                            return Ok(Some(node))
-                        },
-                        _ => {}
+                    if NodeFilterConstants::FILTER_ACCEPT == try!(self.accept_node(node.r())) {
+                        self.current_node.set(JS::from_rooted(&node));
+                        return Ok(Some(node))
                     }
                 },
                 None => break,
@@ -195,12 +192,9 @@ impl<'a> TreeWalkerMethods for &'a TreeWalker {
             }
             // "5. Filter node and if the return value is FILTER_ACCEPT, then
             //     set the currentNode attribute to node and return node."
-            match try!(self.accept_node(node.r())) {
-                NodeFilterConstants::FILTER_ACCEPT => {
-                    self.current_node.set(JS::from_rooted(&node));
-                    return Ok(Some(node))
-                },
-                _ => {}
+            if NodeFilterConstants::FILTER_ACCEPT == try!(self.accept_node(node.r())) {
+                self.current_node.set(JS::from_rooted(&node));
+                return Ok(Some(node))
             }
         }
         // "6. Return null."
@@ -217,9 +211,8 @@ impl<'a> TreeWalkerMethods for &'a TreeWalker {
         loop {
             // "1. While result is not FILTER_REJECT and node has a child, run these subsubsteps:"
             loop {
-                match result {
-                    NodeFilterConstants::FILTER_REJECT => break,
-                    _ => {}
+                if NodeFilterConstants::FILTER_REJECT == result {
+                    break;
                 }
                 match node.r().GetFirstChild() {
                     None => break,
@@ -230,12 +223,9 @@ impl<'a> TreeWalkerMethods for &'a TreeWalker {
                         result = try!(self.accept_node(node.r()));
                         // "3. If result is FILTER_ACCEPT, then
                         //     set the currentNode attribute to node and return node."
-                        match result {
-                            NodeFilterConstants::FILTER_ACCEPT => {
-                                self.current_node.set(JS::from_rooted(&node));
-                                return Ok(Some(node))
-                            },
-                            _ => {}
+                        if NodeFilterConstants::FILTER_ACCEPT == result {
+                            self.current_node.set(JS::from_rooted(&node));
+                            return Ok(Some(node))
                         }
                     }
                 }
@@ -251,12 +241,9 @@ impl<'a> TreeWalkerMethods for &'a TreeWalker {
                     result = try!(self.accept_node(node.r()));
                     // "4. If result is FILTER_ACCEPT, then
                     //     set the currentNode attribute to node and return node."
-                    match result {
-                        NodeFilterConstants::FILTER_ACCEPT => {
-                            self.current_node.set(JS::from_rooted(&node));
-                            return Ok(Some(node))
-                        },
-                        _ => {}
+                    if NodeFilterConstants::FILTER_ACCEPT == result {
+                        self.current_node.set(JS::from_rooted(&node));
+                        return Ok(Some(node))
                     }
                 }
             }
@@ -391,13 +378,11 @@ impl<'a> PrivateTreeWalkerHelpers for &'a TreeWalker {
                 let result = try!(self.accept_node(node.r()));
                 // "3. If result is FILTER_ACCEPT, then set the currentNode
                 //     attribute to node and return node."
-                match result {
-                    NodeFilterConstants::FILTER_ACCEPT => {
-                        self.current_node.set(JS::from_rooted(&node));
-                        return Ok(Some(node))
-                    },
-                    _ => {}
+                if NodeFilterConstants::FILTER_ACCEPT == result {
+                    self.current_node.set(JS::from_rooted(&node));
+                    return Ok(Some(node))
                 }
+
                 // "4. Set sibling to node's first child if type is next,
                 //     and node's last child if type is previous."
                 sibling_op = next_child(node.r());
@@ -418,9 +403,8 @@ impl<'a> PrivateTreeWalkerHelpers for &'a TreeWalker {
                 // "5. Filter node and if the return value is FILTER_ACCEPT, then return null."
                 Some(n) => {
                     node = n;
-                    match try!(self.accept_node(node.r())) {
-                        NodeFilterConstants::FILTER_ACCEPT => return Ok(None),
-                        _ => {}
+                    if NodeFilterConstants::FILTER_ACCEPT == try!(self.accept_node(node.r())) {
+                        return Ok(None)
                     }
                 }
             }
diff --git a/components/script/dom/url.rs b/components/script/dom/url.rs
index 9bbd0f1b5fc..d4a8b5a23ff 100644
--- a/components/script/dom/url.rs
+++ b/components/script/dom/url.rs
@@ -142,7 +142,7 @@ impl<'a> URLMethods for &'a URL {
     }
 }
 
-fn parser_with_base<'a>(base: Option<&'a Url>) -> UrlParser<'a> {
+fn parser_with_base(base: Option<&Url>) -> UrlParser {
     let mut parser = UrlParser::new();
     if let Some(base) = base {
         parser.base_url(base);
diff --git a/components/script/dom/urlhelper.rs b/components/script/dom/urlhelper.rs
index cff468574b2..4376a85e390 100644
--- a/components/script/dom/urlhelper.rs
+++ b/components/script/dom/urlhelper.rs
@@ -84,7 +84,7 @@ impl UrlHelper {
         if urlA.port() != urlB.port() {
             return false
         }
-        return true
+        true
     }
 
     // https://url.spec.whatwg.org/#dom-urlutils-search
diff --git a/components/script/dom/virtualmethods.rs b/components/script/dom/virtualmethods.rs
index b67cbb69d4f..437f39422c6 100644
--- a/components/script/dom/virtualmethods.rs
+++ b/components/script/dom/virtualmethods.rs
@@ -48,7 +48,7 @@ use string_cache::Atom;
 pub trait VirtualMethods {
     /// Returns self as the superclass of the implementation for this trait,
     /// if any.
-    fn super_type<'b>(&'b self) -> Option<&'b VirtualMethods>;
+    fn super_type(&self) -> Option<&VirtualMethods>;
 
     /// Called when changing or adding attributes, after the attribute's value
     /// has been updated.
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 0b6fa7b3869..4acf36256c8 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -514,15 +514,13 @@ impl<'a> WebGLRenderingContextMethods for &'a WebGLRenderingContext {
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.10
     fn VertexAttribPointer(self, attrib_id: u32, size: i32, data_type: u32,
                            normalized: bool, stride: i32, offset: i64) {
-        match data_type {
-            constants::FLOAT => {
-               let msg = CanvasMsg::WebGL(
-                   CanvasWebGLMsg::VertexAttribPointer2f(attrib_id, size, normalized, stride, offset));
-                self.ipc_renderer.send(msg).unwrap()
-            }
-            _ => panic!("VertexAttribPointer: Data Type not supported")
+        if let constants::FLOAT = data_type {
+           let msg = CanvasMsg::WebGL(
+               CanvasWebGLMsg::VertexAttribPointer2f(attrib_id, size, normalized, stride, offset));
+            self.ipc_renderer.send(msg).unwrap()
+        } else {
+            panic!("VertexAttribPointer: Data Type not supported")
         }
-
     }
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.4
diff --git a/components/script/dom/websocket.rs b/components/script/dom/websocket.rs
index 7855c3e453b..1e00a9e507a 100644
--- a/components/script/dom/websocket.rs
+++ b/components/script/dom/websocket.rs
@@ -277,7 +277,7 @@ impl<'a> WebSocketMethods for &'a WebSocket {
         let mut other_sender = self.sender.borrow_mut();
         let my_sender = other_sender.as_mut().unwrap();
         let _ = my_sender.lock().unwrap().send_message(Message::Text(data.unwrap().0));
-        return Ok(())
+        Ok(())
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-websocket-close
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 43e4ca6e642..82e3247dc8e 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -269,19 +269,19 @@ impl Window {
         (box SendableMainThreadScriptChan(tx), box rx)
     }
 
-    pub fn image_cache_task<'a>(&'a self) -> &'a ImageCacheTask {
+    pub fn image_cache_task(&self) -> &ImageCacheTask {
         &self.image_cache_task
     }
 
-    pub fn compositor<'a>(&'a self) -> &'a IpcSender<ScriptToCompositorMsg> {
+    pub fn compositor(&self) -> &IpcSender<ScriptToCompositorMsg> {
         &self.compositor
     }
 
-    pub fn browsing_context<'a>(&'a self) -> Ref<'a, Option<BrowsingContext>> {
+    pub fn browsing_context(&self) -> Ref<Option<BrowsingContext>> {
         self.browsing_context.borrow()
     }
 
-    pub fn page<'a>(&'a self) -> &'a Page {
+    pub fn page(&self) -> &Page {
         &*self.page
     }
 
diff --git a/components/script/dom/workerglobalscope.rs b/components/script/dom/workerglobalscope.rs
index 70477846627..468de091271 100644
--- a/components/script/dom/workerglobalscope.rs
+++ b/components/script/dom/workerglobalscope.rs
@@ -143,11 +143,11 @@ impl WorkerGlobalScope {
         self.runtime.cx()
     }
 
-    pub fn resource_task<'a>(&'a self) -> &'a ResourceTask {
+    pub fn resource_task(&self) -> &ResourceTask {
         &self.resource_task
     }
 
-    pub fn get_url<'a>(&'a self) -> &'a Url {
+    pub fn get_url(&self) -> &Url {
         &self.worker_url
     }
 
diff --git a/components/script/dom/xmlhttprequest.rs b/components/script/dom/xmlhttprequest.rs
index e28482e3f16..577416fe700 100644
--- a/components/script/dom/xmlhttprequest.rs
+++ b/components/script/dom/xmlhttprequest.rs
@@ -784,19 +784,17 @@ impl<'a> PrivateXMLHttpRequestHelpers for &'a XMLHttpRequest {
 
     fn process_headers_available(self, cors_request: Option<CORSRequest>,
                                  gen_id: GenerationId, metadata: Metadata) -> Result<(), Error> {
-        match cors_request {
-            Some(ref req) => {
-                match metadata.headers {
-                    Some(ref h) if allow_cross_origin_request(req, h) => {},
-                    _ => {
-                        self.process_partial_response(XHRProgress::Errored(gen_id, Network));
-                        return Err(Network);
-                    }
+
+        if let Some(ref req) = cors_request {
+            match metadata.headers {
+                Some(ref h) if allow_cross_origin_request(req, h) => {},
+                _ => {
+                    self.process_partial_response(XHRProgress::Errored(gen_id, Network));
+                    return Err(Network);
                 }
-            },
+            }
+        }
 
-            _ => {}
-        };
         // XXXManishearth Clear cache entries in case of a network error
         self.process_partial_response(XHRProgress::HeadersReceived(gen_id,
                                                                    metadata.headers,
diff --git a/components/script/dom/xmlhttprequesteventtarget.rs b/components/script/dom/xmlhttprequesteventtarget.rs
index d93746fed0f..3bf1aa408b0 100644
--- a/components/script/dom/xmlhttprequesteventtarget.rs
+++ b/components/script/dom/xmlhttprequesteventtarget.rs
@@ -28,7 +28,7 @@ impl XMLHttpRequestEventTarget {
     }
 
     #[inline]
-    pub fn eventtarget<'a>(&'a self) -> &'a EventTarget {
+    pub fn eventtarget(&self) -> &EventTarget {
         &self.eventtarget
     }
 }