feat(tcw3): address clippy lints

- `clone_on_copy`
- `type_complexity` (threshold adjusted)
- `collapsible_if`
- `option_map_unit_fn`
- `identity_conversion`
- `iter_nth_zero`
- `eval_order_dependence` (ignored)
- `new_without_default` (adds `impl Default` for a public type)

Unaddressed:
- `len_zero` - This is a bug in clippy:
  <rust-lang/rust-clippy#3807>

.clippy.toml

@@ -0,0 +1 @@
+type-complexity-threshold = 500

tcw3/src/ui/editing/history.rs

@@ -175,16 +175,22 @@ impl<T: ?Sized + CoalescingCb<Text>, Text> CoalescingCb<Text> for &'_ mut T {
     }
 }
 
-impl<Text: TextTrait> CoalescingState<Text> {
-    /// Construct a `CoalescingState`.
-    pub fn new() -> Self {
+impl<Text> Default for CoalescingState<Text> {
+    fn default() -> Self {
         Self {
             composition_active: false,
             has_edit: false,
             num_coalescable_edits: 0,
             _phantom: std::marker::PhantomData,
         }
     }
+}
+
+impl<Text: TextTrait> CoalescingState<Text> {
+    /// Construct a `CoalescingState`.
+    pub fn new() -> Self {
+        Self::default()
+    }
 
     /// Resets the state of the algorithm.
     ///

tcw3/src/ui/scrolling/lineset.rs

@@ -273,7 +273,7 @@ impl Lineset {
             let (mut iter, range) = self
                 .line_grs
                 .range(range_by_key(LineOff::index, Floor(range.start)..));
-            (*iter.nth(0).unwrap(), range.start)
+            (*iter.next().unwrap(), range.start)
         };
 
         // Endpoints of the line group (pre-insertion)

tcw3/src/ui/theming/stylesheet.rs

@@ -411,7 +411,10 @@ macro_rules! rule {
         }
     ) => {{
         let start = $i;
-        $i += $crate::prop_count! { $($props)* };
+        // This lint misfires for `$i`
+        #[allow(clippy::eval_order_dependence)] {
+            $i += $crate::prop_count! { $($props)* };
+        }
         let end = $i;
 
         $crate::ui::theming::Rule {

tcw3/src/ui/theming/view.rs

@@ -215,13 +215,15 @@ impl StyledBox {
         let mut subelems = self.shared.subelems.borrow_mut();
 
         if let Some(i) = subelems.iter().position(|&(r, _)| r == role) {
+            // There's already a subelement with `role`. Replace or remove it
             self.shared.style_elem.remove_child(subelems[i].1);
             if let Some(helem) = helem {
                 subelems[i].1 = helem;
             } else {
                 subelems.swap_remove(i);
             }
         } else {
+            // There's no subelement with `role`
             if let Some(helem) = helem {
                 subelems.push((role, helem));
             }
@@ -452,7 +454,7 @@ impl AbsInnerLayout {
         Self {
             subview_layout: subviews
                 .clone()
-                .map(|&(role, _)| (role, (*props.subview_metrics(role)).clone()))
+                .map(|&(role, _)| (role, *props.subview_metrics(role)))
                 .collect(),
             subviews: subviews.map(|x| x.1.clone()).collect(),
             overrider,
@@ -522,7 +524,7 @@ impl Layout for AbsInnerLayout {
     fn arrange(&self, ctx: &mut LayoutCtx<'_>, size: Vector2<f32>) {
         for (&(role, ref metrics), sv) in self.subview_layout.iter().zip(self.subviews.iter()) {
             let sv_traits = ctx.subview_size_traits(sv.as_ref());
-            let container = box2! {top_left: [0.0, 0.0].into(), size: size.into()};
+            let container = box2! {top_left: [0.0, 0.0].into(), size: size};
 
             let mut frame = metrics.arrange(container, sv_traits.preferred);
 

tcw3/src/ui/views/entry.rs

@@ -1086,7 +1086,7 @@ impl ViewListener for EntryCoreListener {
             .update_layer(wm, view, ctx.hwnd(), visual_bounds, |draw_ctx| {
                 let c = &mut draw_ctx.canvas;
 
-                let mut sel_range = sel_range.clone();
+                let mut sel_range = *sel_range;
                 let text_layout = &text_layout_info.text_layout;
 
                 c.save();
@@ -1313,7 +1313,9 @@ impl pal::iface::TextInputCtxEdit<pal::Wm> for Edit<'_> {
     }
 
     fn set_composition_range(&mut self, range: Option<Range<usize>>) {
-        range.as_ref().map(|r| self.check_range(r));
+        if let Some(r) = &range {
+            self.check_range(r)
+        }
 
         let range = range.map(|r| [r.start, r.end]);
         if range == self.state.comp_range {

tcw3/src/ui/views/slider.rs

@@ -318,6 +318,7 @@ impl SliderRaw {
 
         for &(role, label) in children.iter() {
             if let Some((new_value, new_widget)) = label {
+                // Assign a label
                 let new_value = new_value as f32;
                 let wrap_view =
                     if let Some(label) = labels.iter_mut().find(|label| label.role == role) {
@@ -339,8 +340,8 @@ impl SliderRaw {
                     FillLayout::new(new_widget.view_ref().cloned()).with_margin(wrap_view_margin),
                 );
             } else {
+                // Remove a label if there's one for `role`
                 if let Some(i) = labels.iter().position(|label| label.role == role) {
-                    // Remove the label
                     let label = labels.swap_remove(i);
                     debug_assert_eq!(label.role, role);
                     labels_wrapper.set_subview(role, None);

tcw3/src/ui/views/split.rs

@@ -432,7 +432,7 @@ impl Layout for SplitLayout {
         );
 
         // Arrange the panels
-        let mut frame1 = box2! { top_left: [0.0, 0.0].into(), size: size.into() };
+        let mut frame1 = box2! { top_left: [0.0, 0.0].into(), size: size };
         let mut frame2 = frame1;
         let mut spl_frame = frame1;
 

tcw3/src/uicore/keybd.rs

@@ -182,10 +182,8 @@ impl HWndRef<'_> {
         // Does this window recognize the action?
         let listener = self.wnd.listener.borrow();
         let status = listener.validate_action(wm, self, action);
-        if status.contains(ActionStatus::VALID) {
-            if perform && status.contains(ActionStatus::ENABLED) {
-                listener.perform_action(wm, self, action);
-            }
+        if perform && status.contains(ActionStatus::VALID | ActionStatus::ENABLED) {
+            listener.perform_action(wm, self, action);
         }
         status
     }