Mark extensible enums in winit-core as #[non_exhaustive]

Event, input source, error, data transfer, native key, IME request,
scroll delta and fullscreen enums can now gain variants without a
breaking change. Backends and examples get wildcard arms where they
matched exhaustively; unknown IME requests are reported as
ImeRequestError::NotSupported and unknown fullscreen modes behave
like Fullscreen::Borderless(None).

winit-core/src/cursor.rs

@@ -111,6 +111,7 @@ impl_dyn_casting!(CustomCursorProvider);
 ///
 /// See [`CustomCursor`] for more details.
 #[derive(Debug, Clone, Eq, Hash, PartialEq)]
+#[non_exhaustive]
 pub enum CustomCursorSource {
     /// Cursor that is backed by RGBA image.
     ///
@@ -167,6 +168,7 @@ impl CustomCursorSource {
 /// An error produced when using [`CustomCursorSource::from_rgba`] with invalid arguments.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[non_exhaustive]
 pub enum BadImage {
     /// Produced when the image dimensions are larger than [`MAX_CURSOR_SIZE`]. This doesn't
     /// guarantee that the cursor will work, but should avoid many platform and device specific
@@ -217,6 +219,7 @@ impl Error for BadImage {}
 /// An error produced when using [`CustomCursorSource::from_animation`] with invalid arguments.
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[non_exhaustive]
 pub enum BadAnimation {
     /// Produced when no cursors were supplied.
     Empty,

winit-core/src/data_transfer.rs

@@ -127,6 +127,7 @@ impl DataTransferId {
 
 /// The set of types supported cross-platform.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+#[non_exhaustive]
 pub enum TypeHint {
     /// Plain UTF-8 text (see [`TypedData::try_as_string`]).
     ///
@@ -381,6 +382,7 @@ impl_dyn_casting!(DataTransfer);
 /// different encoding on different platforms. To allow this to be represented, we allow
 /// supplying strings and URIs separately from binary blobs.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[non_exhaustive]
 pub enum SendData {
     /// List of URIs.
     ///

winit-core/src/event.rs

@@ -20,6 +20,7 @@ use crate::window::{ActivationToken, Theme};
 
 /// Describes the reason the event loop is resuming.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[non_exhaustive]
 pub enum StartCause {
     /// Sent if the time specified by [`ControlFlow::WaitUntil`] has been reached. Contains the
     /// moment the timeout was requested and the requested resume time. The actual resume time is
@@ -44,6 +45,7 @@ pub enum StartCause {
 
 /// Describes an event from a [`Window`].
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub enum WindowEvent {
     /// The activation token was delivered back and now could be used.
     ActivationTokenDone { serial: AsyncRequestSerial, token: ActivationToken },
@@ -531,6 +533,7 @@ pub enum WindowEvent {
 /// **Wayland/X11:** [`Unknown`](Self::Unknown) device types are converted to known variants by the
 /// system.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+#[non_exhaustive]
 pub enum PointerKind {
     Mouse,
     /// See [`PointerSource::Touch`] for more details.
@@ -548,6 +551,7 @@ pub enum PointerKind {
 /// **Wayland/X11:** [`Unknown`](Self::Unknown) device types are converted to known variants by the
 /// system.
 #[derive(Clone, Debug, PartialEq)]
+#[non_exhaustive]
 pub enum PointerSource {
     Mouse,
     /// Represents a touch event.
@@ -616,6 +620,7 @@ impl From<PointerSource> for PointerKind {
 /// **Wayland/X11:** [`Unknown`](Self::Unknown) device types are converted to known variants by the
 /// system.
 #[derive(Clone, Debug, PartialEq)]
+#[non_exhaustive]
 pub enum ButtonSource {
     /// ## Platform-specific
     ///
@@ -730,6 +735,7 @@ impl FingerId {
 ///
 /// [window events]: WindowEvent
 #[derive(Clone, Copy, Debug, PartialEq)]
+#[non_exhaustive]
 pub enum DeviceEvent {
     /// Change in physical position of a pointing device.
     ///
@@ -1052,6 +1058,7 @@ impl From<ModifiersState> for Modifiers {
 /// ```
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[non_exhaustive]
 pub enum Ime {
     /// Notifies when the IME was enabled.
     ///
@@ -1576,6 +1583,7 @@ impl From<TabletToolButton> for Option<MouseButton> {
 /// Describes a difference in the mouse scroll wheel state.
 #[derive(Debug, Clone, Copy, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[non_exhaustive]
 pub enum MouseScrollDelta {
     /// Amount in lines or rows to scroll in the horizontal
     /// and vertical directions.

winit-core/src/event_loop/mod.rs

@@ -282,6 +282,7 @@ impl From<Icon> for DragIcon {
 /// are expected to provide some kind of order of preference.
 #[repr(u8)]
 #[derive(Debug, Clone, Copy, PartialEq)]
+#[non_exhaustive]
 pub enum DndAction {
     /// Move the dragged item from the source to the destination.
     ///

winit-core/src/icon.rs

@@ -26,6 +26,7 @@ impl_dyn_casting!(IconProvider);
 
 #[derive(Debug)]
 /// An error produced when using [`RgbaIcon::new`] with invalid arguments.
+#[non_exhaustive]
 pub enum BadIcon {
     /// Produced when the length of the `rgba` argument isn't divisible by 4, thus `rgba` can't be
     /// safely interpreted as 32bpp RGBA pixels.

winit-core/src/keyboard.rs

@@ -19,6 +19,7 @@ pub use smol_str::SmolStr;
 /// - On non-Web platforms, support assigning keybinds to virtually any key through a UI.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[non_exhaustive]
 pub enum NativeKeyCode {
     Unidentified,
     /// An Android "scancode".
@@ -78,6 +79,7 @@ impl std::fmt::Debug for NativeKeyCode {
 /// define keybinds which work in the presence of identifiers we haven't mapped for you yet.
 #[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[non_exhaustive]
 pub enum NativeKey {
     Unidentified,
     /// An Android "keycode", which is similar to a "virtual-key code" on Windows.

winit-core/src/monitor.rs

@@ -183,6 +183,7 @@ impl fmt::Display for VideoMode {
 
 /// Fullscreen modes.
 #[derive(Clone, Debug, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum Fullscreen {
     Exclusive(MonitorHandle, VideoMode),
 

winit-core/src/window.rs

@@ -1756,6 +1756,7 @@ bitflags! {
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Hash)]
+#[non_exhaustive]
 pub enum ImeSurroundingTextError {
     /// Text exceeds 4000 bytes
     TextTooLong,
@@ -1868,6 +1869,7 @@ impl ImeSurroundingText {
 
 /// Request to send to IME.
 #[derive(Debug, PartialEq, Clone)]
+#[non_exhaustive]
 pub enum ImeRequest {
     /// Enable the IME with the [`ImeCapabilities`] and [`ImeRequestData`] as initial state. When
     /// the [`ImeRequestData`] is **not** matching capabilities fully, the default values will be