Fix warning

backends/conrod_gfx/src/lib.rs

@@ -815,14 +815,6 @@ impl From<gfx::PipelineStateError<String>> for RendererCreationError {
     }
 }
 
-impl std::error::Error for RendererCreationError {
-    fn description(&self) -> &str {
-        match *self {
-            RendererCreationError::PipelineState(ref e) => std::error::Error::description(e),
-        }
-    }
-}
-
 impl std::fmt::Display for RendererCreationError {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
         match *self {

backends/conrod_glium/examples/graph.rs

@@ -184,16 +184,16 @@ fn set_widgets(ui: &mut conrod_core::UiCell, ids: &Ids, graph: &mut MyGraph, lay
             Event::Node(event) => match event {
                 // NodeEvent::Add(node_kind) => {
                 // },
-                NodeEvent::Remove(node_id) => {}
+                NodeEvent::Remove(_node_id) => {}
                 NodeEvent::Dragged { node_id, to, .. } => {
                     *layout.get_mut(&node_id).unwrap() = to;
                 }
             },
             Event::Edge(event) => match event {
-                EdgeEvent::AddStart(node_socket) => {}
-                EdgeEvent::Add { start, end } => {}
-                EdgeEvent::Cancelled(node_socket) => {}
-                EdgeEvent::Remove { start, end } => {}
+                EdgeEvent::AddStart(_node_socket) => {}
+                EdgeEvent::Add { start: _, end: _ } => {}
+                EdgeEvent::Cancelled(_node_socket) => {}
+                EdgeEvent::Remove { start: _, end: _ } => {}
             },
         }
     }

backends/conrod_glium/src/lib.rs

@@ -1020,15 +1020,6 @@ impl From<glium::program::ProgramChooserCreationError> for RendererCreationError
     }
 }
 
-impl std::error::Error for RendererCreationError {
-    fn description(&self) -> &str {
-        match *self {
-            RendererCreationError::Texture(ref e) => std::error::Error::description(e),
-            RendererCreationError::Program(ref e) => std::error::Error::description(e),
-        }
-    }
-}
-
 impl std::fmt::Display for RendererCreationError {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
         match *self {
@@ -1050,15 +1041,6 @@ impl From<glium::DrawError> for DrawError {
     }
 }
 
-impl std::error::Error for DrawError {
-    fn description(&self) -> &str {
-        match *self {
-            DrawError::Buffer(ref e) => std::error::Error::description(e),
-            DrawError::Draw(ref e) => std::error::Error::description(e),
-        }
-    }
-}
-
 impl std::fmt::Display for DrawError {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
         match *self {

conrod_core/src/position/mod.rs

@@ -145,10 +145,10 @@ pub enum Dimension {
 /// Thus, **Positionable** can be implemented for *all* types that implement **Widget**.
 pub trait Positionable: Sized {
     /// Build with the given **Position** along the *x* axis.
-    fn x_position(self, Position) -> Self;
+    fn x_position(self, _: Position) -> Self;
 
     /// Build with the given **Position** along the *y* axis.
-    fn y_position(self, Position) -> Self;
+    fn y_position(self, _: Position) -> Self;
 
     /// Get the **Position** along the *x* axis.
     fn get_x_position(&self, ui: &Ui) -> Position;

conrod_core/src/widget/list.rs

@@ -61,10 +61,10 @@ pub trait Direction {
     type Axis: widget::scrollbar::Axis;
 
     /// For some given `Rect`, returns the parallel and perpendicular ranges respectively.
-    fn ranges(Rect) -> (Range, Range);
+    fn ranges(_: Rect) -> (Range, Range);
 
     /// Begin building the scrollbar for the `List`.
-    fn scrollbar(widget::Id) -> widget::Scrollbar<Self::Axis>;
+    fn scrollbar(_: widget::Id) -> widget::Scrollbar<Self::Axis>;
 
     /// Borrow the scroll state associated with this `Direction`'s axis.
     fn common_scroll(common: &widget::CommonBuilder) -> Option<&widget::scroll::Scroll>;
@@ -105,8 +105,8 @@ pub trait Direction {
 pub trait ItemSize: Sized + Clone + Copy {
     /// Update the `List` widget.
     fn update_list<D>(
-        List<D, Self>,
-        widget::UpdateArgs<List<D, Self>>,
+        _: List<D, Self>,
+        _: widget::UpdateArgs<List<D, Self>>,
     ) -> <List<D, Self> as Widget>::Event
     where
         D: Direction;

conrod_core/src/widget/list_select.rs

@@ -48,24 +48,24 @@ pub trait Mode {
     /// Update the `PendingEvents` in accordance with the given `Click` event.
     fn click_selection<F, D, S>(
         &self,
-        event::Click,
+        _: event::Click,
         i: usize,
         num_items: usize,
-        &State,
+        _: &State,
         is_selected: F,
-        &mut PendingEvents<Self::Selection, D, S>,
+        _: &mut PendingEvents<Self::Selection, D, S>,
     ) where
         F: Fn(usize) -> bool;
 
     /// Update the `PendingEvents` in accordance with the given `KeyPress` event.
     fn key_selection<F, D, S>(
         &self,
-        event::KeyPress,
+        _: event::KeyPress,
         i: usize,
         num_items: usize,
-        &State,
+        _: &State,
         is_selected: F,
-        &mut PendingEvents<Self::Selection, D, S>,
+        _: &mut PendingEvents<Self::Selection, D, S>,
     ) where
         F: Fn(usize) -> bool,
         D: Direction;

conrod_core/src/widget/mod.rs

@@ -606,7 +606,7 @@ pub trait Widget: Common + Sized {
     ///
     /// The `Ui` will only call this once, immediately prior to the first time that
     /// **Widget::update** is first called.
-    fn init_state(&self, id::Generator) -> Self::State;
+    fn init_state(&self, _: id::Generator) -> Self::State;
 
     /// Return the styling of the widget.
     ///

conrod_core/src/widget/primitive/shape/triangles.rs

@@ -26,7 +26,7 @@ pub trait Vertex: Clone + Copy + PartialEq {
     /// The x y location of the vertex.
     fn point(&self) -> Point;
     /// Add the given vector onto the position of self and return the result.
-    fn add(self, Point) -> Self;
+    fn add(self, _: Point) -> Self;
 }
 
 /// Unique styling types for `Triangles`.

conrod_core/src/widget/scroll.rs

@@ -36,11 +36,11 @@ pub struct State<A> {
 /// Methods for distinguishing behaviour between both scroll axes at compile-time.
 pub trait Axis {
     /// The range of the given `Rect` that is parallel with this `Axis`.
-    fn parallel_range(Rect) -> Range;
+    fn parallel_range(_: Rect) -> Range;
     /// The range of the given `Rect` that is perpendicular with this `Axis`.
-    fn perpendicular_range(Rect) -> Range;
+    fn perpendicular_range(_: Rect) -> Range;
     /// Given some rectangular `Padding`, return the `Range` that corresponds with this `Axis`.
-    fn padding_range(Padding) -> Range;
+    fn padding_range(_: Padding) -> Range;
     /// The coordinate of the given mouse position that corresponds with this `Axis`.
     fn mouse_scalar(mouse_xy: Point) -> Scalar;
     /// A `Scalar` multiplier representing the direction in which positive offset shifts the