Warn on exhaustive exported enums

Enable clippy::exhaustive_enums in every crate so new exported enums
are either #[non_exhaustive] or explicitly allowed as a closed set.

winit-core/src/cursor.rs

@@ -17,6 +17,7 @@ const PIXEL_SIZE: usize = 4;
 
 /// See [`Window::set_cursor()`][crate::window::Window::set_cursor] for more details.
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
+#[allow(clippy::exhaustive_enums)]
 pub enum Cursor {
     Icon(CursorIcon),
     Custom(CustomCursor),

winit-core/src/event.rs

@@ -1107,6 +1107,7 @@ pub enum Ime {
 /// Describes touch-screen input state.
 #[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum TouchPhase {
     /// Initial touch contact or gesture start, for example when one or more fingers touch the
     /// screen or touchpad.
@@ -1126,6 +1127,7 @@ pub enum TouchPhase {
 #[derive(Debug, Clone, Copy, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[doc(alias = "Pressure")]
+#[allow(clippy::exhaustive_enums)]
 pub enum Force {
     /// On iOS, the force is calibrated so that the same number corresponds to
     /// roughly the same amount of pressure on the screen regardless of the
@@ -1436,6 +1438,7 @@ impl TabletToolAngle {
 /// Describes the input state of a key.
 #[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum ElementState {
     Pressed,
     Released,
@@ -1466,6 +1469,7 @@ impl ElementState {
 #[derive(Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[repr(u8)]
+#[allow(clippy::exhaustive_enums)]
 pub enum MouseButton {
     /// The primary (usually left) button
     Left = 0,
@@ -1561,6 +1565,7 @@ impl MouseButton {
 /// Describes a button of a tool, e.g. a pen.
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum TabletToolButton {
     Contact,
     Barrel,

winit-core/src/event_loop/mod.rs

@@ -415,6 +415,7 @@ impl Eq for OwnedDisplayHandle {}
 /// [`Wait`]: Self::Wait
 /// [`about_to_wait`]: crate::application::ApplicationHandler::about_to_wait
 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, Hash)]
+#[allow(clippy::exhaustive_enums)]
 pub enum ControlFlow {
     /// When the current loop iteration finishes, immediately begin a new iteration regardless of
     /// whether or not new events are available to process.
@@ -454,6 +455,7 @@ impl ControlFlow {
 /// Control when device events are captured.
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Default)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum DeviceEvents {
     /// Report device events regardless of window focus.
     Always,

winit-core/src/event_loop/pump_events.rs

@@ -108,6 +108,7 @@ pub trait EventLoopExtPumpEvents {
 
 /// The return status for `pump_events`
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+#[allow(clippy::exhaustive_enums)]
 pub enum PumpStatus {
     /// Continue running external loop.
     Continue,

winit-core/src/keyboard.rs

@@ -169,6 +169,7 @@ impl PartialEq<NativeKeyCode> for NativeKey {
 /// emit [`PhysicalKey::Unidentified`] with additional data about the key.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum PhysicalKey {
     /// A known key code
     Code(KeyCode),
@@ -250,6 +251,7 @@ impl PartialEq<PhysicalKey> for NativeKeyCode {
 /// [`KeyboardEvent.key`]: https://w3c.github.io/uievents-key/
 #[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum Key<Str = SmolStr> {
     /// A simple (unparameterised) action
     Named(NamedKey),
@@ -447,6 +449,7 @@ impl ModifiersState {
 /// [^2]: platform-dependent
 #[derive(Default, Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum ModifiersKeyState {
     /// The particular modifier is active or logically, but not necessarily physically, pressed.
     Pressed,

winit-core/src/lib.rs

@@ -7,6 +7,12 @@
 //!
 //! [`winit`]: https://docs.rs/winit
 
+// Every newly exported enum should either be `#[non_exhaustive]`, or carry an `#[allow]` of
+// this lint when the set of variants can never grow.
+// `clippy::exhaustive_structs` is deliberately not enabled: event structs must stay
+// constructible by the backend crates, which `#[non_exhaustive]` would forbid.
+#![warn(clippy::exhaustive_enums)]
+
 #[macro_use]
 pub mod as_any;
 pub mod cursor;

winit-core/src/window.rs

@@ -1544,6 +1544,7 @@ impl rwh_06::HasWindowHandle for dyn Window + '_ {
 /// Use this enum with [`Window::set_cursor_grab`] to grab the cursor.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum CursorGrabMode {
     /// No grabbing of the cursor is performed.
     None,
@@ -1574,6 +1575,7 @@ pub enum CursorGrabMode {
 /// Defines the orientation that a window resize will be performed.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum ResizeDirection {
     East,
     North,
@@ -1604,6 +1606,7 @@ impl From<ResizeDirection> for CursorIcon {
 /// The theme variant to use.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum Theme {
     /// Use the light variant.
     Light,
@@ -1621,6 +1624,7 @@ pub enum Theme {
 /// [`Informational`]: Self::Informational
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum UserAttentionType {
     /// ## Platform-specific
     ///
@@ -1656,6 +1660,7 @@ bitflags::bitflags! {
 /// - **iOS / Android / Web / Wayland:** Unsupported.
 #[derive(Debug, Default, PartialEq, Eq, Clone, Copy, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[allow(clippy::exhaustive_enums)]
 pub enum WindowLevel {
     /// The window will always be below normal windows.
     ///