Address some issues found by rust-clippy.

src/aabbtree.rs

@@ -280,7 +280,7 @@ impl AABBTree {
         let children = {
             let node = self.node_mut(node_index);
             if node.split_rect.intersects(rect) {
-                if node.draw_list_group_segments.len() > 0 &&
+                if !node.draw_list_group_segments.is_empty() &&
                    node.actual_rect.intersects(rect) {
                     debug_assert!(node.children.is_none());
                     node.is_visible = true;
@@ -304,7 +304,7 @@ impl AABBTree {
         for node in &mut self.nodes {
             node.is_visible = false;
         }
-        if self.nodes.len() > 0 {
+        if !self.nodes.is_empty() {
             self.check_node_visibility(NodeIndex(0), &rect);
         }
     }

src/batch.rs

@@ -289,7 +289,7 @@ impl<'a> BatchBuilder<'a> {
         old_rect
     }
 
-    pub fn push_complex_clip(&mut self, clip: &Vec<ComplexClipRegion>) {
+    pub fn push_complex_clip(&mut self, clip: &[ComplexClipRegion]) {
         // TODO(gw): Handle nested complex clips!
         debug_assert!(clip.len() == 0 || clip.len() == 1);
         if clip.len() == 1 {

src/debug_render.rs

@@ -162,9 +162,9 @@ impl DebugRenderer {
     pub fn render(&mut self,
                   device: &mut Device,
                   viewport_size: &Size2D<u32>) {
-        if self.font_indices.len() > 0 ||
-           self.line_vertices.len() > 0 ||
-           self.tri_vertices.len() > 0 {
+        if !self.font_indices.is_empty() ||
+           !self.line_vertices.is_empty() ||
+           !self.tri_vertices.is_empty() {
             gl::disable(gl::DEPTH_TEST);
             gl::enable(gl::BLEND);
             gl::blend_equation(gl::FUNC_ADD);

src/frame.rs

@@ -181,7 +181,7 @@ impl RenderTarget {
                                         resource_cache: &mut ResourceCache,
                                         draw_list_groups: &HashMap<DrawListGroupId, DrawListGroup, BuildHasherDefault<FnvHasher>>,
                                         layers: &HashMap<ScrollLayerId, Layer, BuildHasherDefault<FnvHasher>>,
-                                        stacking_context_info: &Vec<StackingContextInfo>,
+                                        stacking_context_info: &[StackingContextInfo],
                                         device_pixel_ratio: f32) -> DrawLayer {
         let mut commands = vec![];
         for item in &self.items {
@@ -514,7 +514,7 @@ impl StackingContextHelpers for StackingContext {
         if self.needs_composition_operation_for_mix_blend_mode() {
             composition_operations.push(CompositionOp::MixBlend(self.mix_blend_mode));
         }
-        for filter in self.filters.iter() {
+        for filter in &self.filters {
             match *filter {
                 FilterOp::Blur(radius) => {
                     composition_operations.push(CompositionOp::Filter(LowLevelFilterOp::Blur(
@@ -776,7 +776,7 @@ impl Frame {
     }
 
     fn add_items_to_target(&mut self,
-                           scene_items: &Vec<SceneItem>,
+                           scene_items: &[SceneItem],
                            info: &FlattenInfo,
                            target: &mut RenderTarget,
                            context: &mut FlattenContext,

src/internal_types.rs

@@ -212,7 +212,7 @@ impl PackedVertexForQuad {
                muv: &RectUv<DevicePixel>,
                color_mode: PackedVertexColorMode)
                -> PackedVertexForQuad {
-        return PackedVertexForQuad {
+        PackedVertexForQuad {
             x: position.origin.x,
             y: position.origin.y,
             width: position.size.width,
@@ -244,7 +244,7 @@ impl PackedVertexForQuad {
                 PackedVertexColorMode::Gradient => 0x00,
                 PackedVertexColorMode::BorderCorner => 0x80,
             },
-        };
+        }
     }
 }
 

src/node_compiler.rs

@@ -19,7 +19,7 @@ pub trait NodeCompiler {
                resource_cache: &ResourceCache,
                frame_id: FrameId,
                device_pixel_ratio: f32,
-               stacking_context_info: &Vec<StackingContextInfo>,
+               stacking_context_info: &[StackingContextInfo],
                draw_list_groups: &HashMap<DrawListGroupId, DrawListGroup, BuildHasherDefault<FnvHasher>>);
 }
 
@@ -28,7 +28,7 @@ impl NodeCompiler for AABBTreeNode {
                resource_cache: &ResourceCache,
                frame_id: FrameId,
                device_pixel_ratio: f32,
-               stacking_context_info: &Vec<StackingContextInfo>,
+               stacking_context_info: &[StackingContextInfo],
                draw_list_groups: &HashMap<DrawListGroupId, DrawListGroup, BuildHasherDefault<FnvHasher>>) {
         let mut compiled_node = CompiledNode::new();
         let mut vertex_buffer = VertexBuffer::new();
@@ -134,7 +134,7 @@ impl NodeCompiler for AABBTreeNode {
             }
 
             let batches = builder.finalize();
-            if batches.len() > 0 {
+            if !batches.is_empty() {
                 compiled_node.batch_list.push(BatchList {
                     batches: batches,
                     draw_list_group_id: draw_list_group_segment.draw_list_group_id,

src/profiler.rs

@@ -239,7 +239,7 @@ impl ProfileGraph {
             stats.max_value = stats.max_value.max(*value);
         }
 
-        if self.values.len() > 0 {
+        if !self.values.is_empty() {
             stats.mean_value = stats.mean_value / self.values.len() as f32;
         }
 

src/render_backend.rs

@@ -57,7 +57,7 @@ impl RenderBackend {
                                                 device_pixel_ratio,
                                                 enable_aa);
 
-        let backend = RenderBackend {
+        RenderBackend {
             thread_pool: thread_pool,
             api_rx: api_rx,
             result_tx: result_tx,
@@ -70,9 +70,7 @@ impl RenderBackend {
             webrender_context_handle: webrender_context_handle,
             webgl_contexts: HashMap::new(),
             current_bound_webgl_context_id: None,
-        };
-
-        backend
+        }
     }
 
     pub fn run(&mut self) {
@@ -295,7 +293,7 @@ impl RenderBackend {
                                      self.device_pixel_ratio);
 
         let pending_update = self.resource_cache.pending_updates();
-        if pending_update.updates.len() > 0 {
+        if !pending_update.updates.is_empty() {
             self.result_tx.send(ResultMsg::UpdateTextureCache(pending_update)).unwrap();
         }
 

src/renderer.rs

@@ -894,7 +894,7 @@ impl Renderer {
                                    f: F)
                                    where F: Fn(&Rect<f32>) -> [PackedVertexForTextureCacheUpdate; 4] {
         // FIXME(pcwalton): Use a hash table if this linear search shows up in the profile.
-        for batch in self.raster_batches.iter_mut() {
+        for batch in &mut self.raster_batches {
             if batch.add_rect_if_possible(dest_texture_id,
                                           color_texture_id,
                                           program_id,
@@ -932,7 +932,7 @@ impl Renderer {
 
     fn flush_raster_batches(&mut self) {
         let batches = mem::replace(&mut self.raster_batches, vec![]);
-        if batches.len() > 0 {
+        if !batches.is_empty() {
             //println!("flushing {:?} raster batches", batches.len());
 
             gl::disable(gl::DEPTH_TEST);
@@ -1201,7 +1201,7 @@ impl Renderer {
                     self.device.bind_program(self.quad_program_id,
                                              &projection);
 
-                    if info.offset_palette.len() > 0 {
+                    if !info.offset_palette.is_empty() {
                         // TODO(gw): Avoid alloc here...
                         let mut floats = Vec::new();
                         for vec in &info.offset_palette {
@@ -1313,7 +1313,7 @@ impl Renderer {
                                 draw_call.first_instance);
                             self.device.bind_vao(vao_id);
 
-                            if draw_call.tile_params.len() > 0 {
+                            if !draw_call.tile_params.is_empty() {
                                 // TODO(gw): Avoid alloc here...
                                 let mut floats = Vec::new();
                                 for vec in &draw_call.tile_params {
@@ -1327,7 +1327,7 @@ impl Renderer {
                                                                    &floats);
                             }
 
-                            if draw_call.clip_rects.len() > 0 {
+                            if !draw_call.clip_rects.is_empty() {
                                 // TODO(gw): Avoid alloc here...
                                 let mut floats = Vec::new();
                                 for rect in &draw_call.clip_rects {

src/resource_cache.rs

@@ -94,7 +94,7 @@ impl<K,V> ResourceClassCache<K,V> where K: Clone + Hash + Eq + Debug, V: Resourc
 
     fn expire_old_resources(&mut self, texture_cache: &mut TextureCache, frame_id: FrameId) {
         let mut resources_to_destroy = vec![];
-        for (key, this_frame_id) in self.last_access_times.iter() {
+        for (key, this_frame_id) in &self.last_access_times {
             if *this_frame_id < frame_id {
                 resources_to_destroy.push((*key).clone())
             }

src/resource_list.rs

@@ -160,7 +160,7 @@ impl BuildRequiredResources for AABBTreeNode {
                     let display_item = &draw_list.items[index as usize];
 
                     // Handle border radius for complex clipping regions.
-                    for complex_clip_region in display_item.clip.complex.iter() {
+                    for complex_clip_region in &display_item.clip.complex {
                         resource_list.add_radius_raster_for_border_radii(&complex_clip_region.radii);
                     }
 

src/texture_cache.rs

@@ -822,7 +822,7 @@ impl TextureCache {
                         }
                     }
 
-                    for update in self.pending_updates.updates.iter_mut() {
+                    for update in &mut self.pending_updates.updates {
                         if update.id == old_texture_id {
                             update.id = new_texture_id
                         }

src/util.rs

@@ -49,7 +49,7 @@ impl MatrixHelpers for Matrix4 {
         let bottom_right = self.transform_point(&rect.bottom_right());
         let (mut min_x, mut min_y) = (top_left.x.clone(), top_left.y.clone());
         let (mut max_x, mut max_y) = (min_x.clone(), min_y.clone());
-        for point in [ top_right, bottom_left, bottom_right ].iter() {
+        for point in &[ top_right, bottom_left, bottom_right ] {
             if point.x < min_x {
                 min_x = point.x.clone()
             }