api: unify error handling

Make error infrastructure more backend agnostic and let backends
just forward the os errors opaquely.

examples/window.rs

@@ -17,7 +17,7 @@ use rwh_06::{DisplayHandle, HasDisplayHandle};
 use softbuffer::{Context, Surface};
 use winit::application::ApplicationHandler;
 use winit::dpi::{LogicalSize, PhysicalPosition, PhysicalSize};
-use winit::error::ExternalError;
+use winit::error::RequestError;
 use winit::event::{DeviceEvent, DeviceId, Ime, MouseButton, MouseScrollDelta, WindowEvent};
 use winit::event_loop::{ActiveEventLoop, EventLoop};
 use winit::keyboard::{Key, ModifiersState};
@@ -76,7 +76,7 @@ struct Application {
     receiver: Receiver<Action>,
     sender: Sender<Action>,
     /// Custom cursors assets.
-    custom_cursors: Result<Vec<CustomCursor>, ExternalError>,
+    custom_cursors: Result<Vec<CustomCursor>, RequestError>,
     /// Application icon.
     icon: Icon,
     windows: HashMap<WindowId, WindowState>,

src/error.rs

@@ -1,45 +1,40 @@
-use std::{error, fmt};
+use std::error::Error;
+use std::fmt::{self, Display};
 
-use crate::platform_impl;
+/// A general error that may occur while running or creating
-
+/// the event loop.
-// TODO: Rename
-/// An error that may be generated when requesting Winit state
-#[derive(Debug)]
-pub enum ExternalError {
-    /// The operation is not supported by the backend.
-    NotSupported(NotSupportedError),
-    /// The operation was ignored.
-    Ignored,
-    /// The OS cannot perform the operation.
-    Os(OsError),
-}
-
-/// The error type for when the requested operation is not supported by the backend.
-#[derive(Clone, Copy, Default, Eq, Hash, PartialEq)]
-#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-pub struct NotSupportedError {
-    _marker: (),
-}
-
-/// The error type for when the OS cannot perform the requested operation.
-#[derive(Debug)]
-pub struct OsError {
-    line: u32,
-    file: &'static str,
-    error: platform_impl::OsError,
-}
-
-/// A general error that may occur while running the Winit event loop
 #[derive(Debug)]
+#[non_exhaustive]
 pub enum EventLoopError {
-    /// The operation is not supported by the backend.
-    NotSupported(NotSupportedError),
-    /// The OS cannot perform the operation.
-    Os(OsError),
     /// The event loop can't be re-created.
     RecreationAttempt,
     /// Application has exit with an error status.
     ExitFailure(i32),
+    /// Got unspecified OS-specific error during the request.
+    Os(OsError),
+    /// Creating the event loop with the requested configuration is not supported.
+    NotSupported(NotSupportedError),
+}
+
+impl fmt::Display for EventLoopError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::RecreationAttempt => write!(f, "EventLoop can't be recreated"),
+            Self::Os(err) => err.fmt(f),
+            Self::ExitFailure(status) => write!(f, "Exit Failure: {status}"),
+            Self::NotSupported(err) => err.fmt(f),
+        }
+    }
+}
+
+impl Error for EventLoopError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        if let Self::Os(err) = self {
+            err.source()
+        } else {
+            None
+        }
+    }
 }
 
 impl From<OsError> for EventLoopError {
@@ -48,18 +43,102 @@ impl From<OsError> for EventLoopError {
     }
 }
 
-impl NotSupportedError {
+impl From<NotSupportedError> for EventLoopError {
-    #[inline]
+    fn from(value: NotSupportedError) -> Self {
-    #[allow(dead_code)]
+        Self::NotSupported(value)
-    pub(crate) fn new() -> NotSupportedError {
-        NotSupportedError { _marker: () }
     }
 }
 
+/// A general error that may occur during a request to the windowing system.
+#[derive(Debug)]
+#[non_exhaustive]
+pub enum RequestError {
+    /// The request is not supported.
+    NotSupported(NotSupportedError),
+    /// The request was ignored by the operating system.
+    Ignored,
+    /// Got unspecified OS specific error during the request.
+    Os(OsError),
+}
+
+impl Display for RequestError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::NotSupported(err) => err.fmt(f),
+            Self::Ignored => write!(f, "The request was ignored"),
+            Self::Os(err) => err.fmt(f),
+        }
+    }
+}
+impl Error for RequestError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        if let Self::Os(err) = self {
+            err.source()
+        } else {
+            None
+        }
+    }
+}
+
+impl From<NotSupportedError> for RequestError {
+    fn from(value: NotSupportedError) -> Self {
+        Self::NotSupported(value)
+    }
+}
+
+impl From<OsError> for RequestError {
+    fn from(value: OsError) -> Self {
+        Self::Os(value)
+    }
+}
+
+/// The requested operation is not supported.
+#[derive(Debug)]
+pub struct NotSupportedError {
+    /// The reason why a certain operation is not supported.
+    reason: &'static str,
+}
+
+impl NotSupportedError {
+    pub(crate) fn new(reason: &'static str) -> Self {
+        Self { reason }
+    }
+}
+
+impl fmt::Display for NotSupportedError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Operation is not supported: {}", self.reason)
+    }
+}
+impl Error for NotSupportedError {}
+
+/// Unclassified error from the OS.
+#[derive(Debug)]
+pub struct OsError {
+    line: u32,
+    file: &'static str,
+    error: Box<dyn Error + Send + Sync + 'static>,
+}
+
 impl OsError {
     #[allow(dead_code)]
-    pub(crate) fn new(line: u32, file: &'static str, error: platform_impl::OsError) -> OsError {
+    pub(crate) fn new(
-        OsError { line, file, error }
+        line: u32,
+        file: &'static str,
+        error: impl Into<Box<dyn Error + Send + Sync + 'static>>,
+    ) -> Self {
+        Self { line, file, error: error.into() }
+    }
+}
+
+impl Display for OsError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad(&format!("os error at {}:{}: {}", self.file, self.line, self.error))
+    }
+}
+impl Error for OsError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        Some(self.error.as_ref())
     }
 }
 
@@ -69,64 +148,3 @@ macro_rules! os_error {
         crate::error::OsError::new(line!(), file!(), $error)
     }};
 }
-
-impl fmt::Display for OsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        f.pad(&format!("os error at {}:{}: {}", self.file, self.line, self.error))
-    }
-}
-
-impl fmt::Display for ExternalError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        match self {
-            ExternalError::NotSupported(e) => e.fmt(f),
-            ExternalError::Ignored => write!(f, "Operation was ignored"),
-            ExternalError::Os(e) => e.fmt(f),
-        }
-    }
-}
-
-impl fmt::Debug for NotSupportedError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        f.debug_struct("NotSupportedError").finish()
-    }
-}
-
-impl fmt::Display for NotSupportedError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        f.pad("the requested operation is not supported by Winit")
-    }
-}
-
-impl fmt::Display for EventLoopError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        match self {
-            EventLoopError::RecreationAttempt => write!(f, "EventLoop can't be recreated"),
-            EventLoopError::NotSupported(e) => e.fmt(f),
-            EventLoopError::Os(e) => e.fmt(f),
-            EventLoopError::ExitFailure(status) => write!(f, "Exit Failure: {status}"),
-        }
-    }
-}
-
-impl error::Error for OsError {}
-impl error::Error for ExternalError {}
-impl error::Error for NotSupportedError {}
-impl error::Error for EventLoopError {}
-
-#[cfg(test)]
-#[allow(clippy::redundant_clone)]
-mod tests {
-    use super::*;
-
-    // Eat attributes for testing
-    #[test]
-    fn ensure_fmt_does_not_panic() {
-        let _ = format!("{:?}, {}", NotSupportedError::new(), NotSupportedError::new().clone());
-        let _ = format!(
-            "{:?}, {}",
-            ExternalError::NotSupported(NotSupportedError::new()),
-            ExternalError::NotSupported(NotSupportedError::new())
-        );
-    }
-}

src/event.rs

@@ -46,7 +46,7 @@ use smol_str::SmolStr;
 use web_time::Instant;
 
 use crate::dpi::{PhysicalPosition, PhysicalSize};
-use crate::error::ExternalError;
+use crate::error::RequestError;
 use crate::event_loop::AsyncRequestSerial;
 use crate::keyboard::{self, ModifiersKeyState, ModifiersKeys, ModifiersState};
 use crate::platform_impl;
@@ -1016,12 +1016,12 @@ impl SurfaceSizeWriter {
     pub fn request_surface_size(
         &mut self,
         new_surface_size: PhysicalSize<u32>,
-    ) -> Result<(), ExternalError> {
+    ) -> Result<(), RequestError> {
         if let Some(inner) = self.new_surface_size.upgrade() {
             *inner.lock().unwrap() = new_surface_size;
             Ok(())
         } else {
-            Err(ExternalError::Ignored)
+            Err(RequestError::Ignored)
         }
     }
 }

src/event_loop.rs

@@ -20,7 +20,7 @@ use std::time::{Duration, Instant};
 use web_time::{Duration, Instant};
 
 use crate::application::ApplicationHandler;
-use crate::error::{EventLoopError, ExternalError, OsError};
+use crate::error::{EventLoopError, RequestError};
 use crate::monitor::MonitorHandle;
 use crate::platform_impl;
 use crate::utils::AsAny;
@@ -268,7 +268,7 @@ impl EventLoop {
     pub fn create_custom_cursor(
         &self,
         custom_cursor: CustomCursorSource,
-    ) -> Result<CustomCursor, ExternalError> {
+    ) -> Result<CustomCursor, RequestError> {
         self.event_loop.window_target().create_custom_cursor(custom_cursor)
     }
 }
@@ -324,7 +324,7 @@ pub trait ActiveEventLoop: AsAny {
     fn create_window(
         &self,
         window_attributes: WindowAttributes,
-    ) -> Result<Box<dyn Window>, OsError>;
+    ) -> Result<Box<dyn Window>, RequestError>;
 
     /// Create custom cursor.
     ///
@@ -334,7 +334,7 @@ pub trait ActiveEventLoop: AsAny {
     fn create_custom_cursor(
         &self,
         custom_cursor: CustomCursorSource,
-    ) -> Result<CustomCursor, ExternalError>;
+    ) -> Result<CustomCursor, RequestError>;
 
     /// Returns the list of all the monitors available on the system.
     ///

src/platform/startup_notify.rs

@@ -23,7 +23,7 @@
 
 use std::env;
 
-use crate::error::NotSupportedError;
+use crate::error::{NotSupportedError, RequestError};
 use crate::event_loop::{ActiveEventLoop, AsyncRequestSerial};
 #[cfg(wayland_platform)]
 use crate::platform::wayland::ActiveEventLoopExtWayland;
@@ -46,7 +46,7 @@ pub trait WindowExtStartupNotify {
     /// Request a new activation token.
     ///
     /// The token will be delivered inside
-    fn request_activation_token(&self) -> Result<AsyncRequestSerial, NotSupportedError>;
+    fn request_activation_token(&self) -> Result<AsyncRequestSerial, RequestError>;
 }
 
 pub trait WindowAttributesExtStartupNotify {
@@ -73,7 +73,7 @@ impl EventLoopExtStartupNotify for dyn ActiveEventLoop + '_ {
 }
 
 impl WindowExtStartupNotify for dyn Window + '_ {
-    fn request_activation_token(&self) -> Result<AsyncRequestSerial, NotSupportedError> {
+    fn request_activation_token(&self) -> Result<AsyncRequestSerial, RequestError> {
         #[cfg(wayland_platform)]
         if let Some(window) = self.as_any().downcast_ref::<crate::platform_impl::wayland::Window>()
         {
@@ -87,7 +87,7 @@ impl WindowExtStartupNotify for dyn Window + '_ {
             return window.request_activation_token();
         }
 
-        Err(NotSupportedError::new())
+        Err(NotSupportedError::new("startup notify is not supported").into())
     }
 }
 

src/platform_impl/android/mod.rs

@@ -14,7 +14,7 @@ use tracing::{debug, trace, warn};
 use crate::application::ApplicationHandler;
 use crate::cursor::Cursor;
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{self, EventLoopError, ExternalError, NotSupportedError};
+use crate::error::{EventLoopError, NotSupportedError, RequestError};
 use crate::event::{self, Force, StartCause, SurfaceSizeWriter};
 use crate::event_loop::{
     ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents,
@@ -592,15 +592,15 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: WindowAttributes,
-    ) -> Result<Box<dyn CoreWindow>, error::OsError> {
+    ) -> Result<Box<dyn CoreWindow>, RequestError> {
         Ok(Box::new(Window::new(self, window_attributes)?))
     }
 
     fn create_custom_cursor(
         &self,
         _source: CustomCursorSource,
-    ) -> Result<CustomCursor, ExternalError> {
+    ) -> Result<CustomCursor, RequestError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("create_custom_cursor is not supported").into())
     }
 
     fn available_monitors(&self) -> Box<dyn Iterator<Item = RootMonitorHandle>> {
@@ -715,7 +715,7 @@ impl Window {
     pub(crate) fn new(
         el: &ActiveEventLoop,
         _window_attrs: window::WindowAttributes,
-    ) -> Result<Self, error::OsError> {
+    ) -> Result<Self, RequestError> {
         // FIXME this ignores requested window attributes
 
         Ok(Self { app: el.app.clone(), redraw_requester: el.redraw_requester.clone() })
@@ -796,12 +796,12 @@ impl CoreWindow for Window {
 
     fn pre_present_notify(&self) {}
 
-    fn inner_position(&self) -> Result<PhysicalPosition<i32>, error::NotSupportedError> {
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
-        Err(error::NotSupportedError::new())
+        Err(NotSupportedError::new("inner_position is not supported").into())
     }
 
-    fn outer_position(&self) -> Result<PhysicalPosition<i32>, error::NotSupportedError> {
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
-        Err(error::NotSupportedError::new())
+        Err(NotSupportedError::new("outer_position is not supported").into())
     }
 
     fn set_outer_position(&self, _position: Position) {
@@ -896,29 +896,29 @@ impl CoreWindow for Window {
 
     fn set_cursor(&self, _: Cursor) {}
 
-    fn set_cursor_position(&self, _: Position) -> Result<(), error::ExternalError> {
+    fn set_cursor_position(&self, _: Position) -> Result<(), RequestError> {
-        Err(error::ExternalError::NotSupported(error::NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_position is not supported").into())
     }
 
-    fn set_cursor_grab(&self, _: CursorGrabMode) -> Result<(), error::ExternalError> {
+    fn set_cursor_grab(&self, _: CursorGrabMode) -> Result<(), RequestError> {
-        Err(error::ExternalError::NotSupported(error::NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_grab is not supported").into())
     }
 
     fn set_cursor_visible(&self, _: bool) {}
 
-    fn drag_window(&self) -> Result<(), error::ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
-        Err(error::ExternalError::NotSupported(error::NotSupportedError::new()))
+        Err(NotSupportedError::new("drag_window is not supported").into())
     }
 
-    fn drag_resize_window(&self, _direction: ResizeDirection) -> Result<(), error::ExternalError> {
+    fn drag_resize_window(&self, _direction: ResizeDirection) -> Result<(), RequestError> {
-        Err(error::ExternalError::NotSupported(error::NotSupportedError::new()))
+        Err(NotSupportedError::new("drag_resize_window").into())
     }
 
     #[inline]
     fn show_window_menu(&self, _position: Position) {}
 
-    fn set_cursor_hittest(&self, _hittest: bool) -> Result<(), error::ExternalError> {
+    fn set_cursor_hittest(&self, _hittest: bool) -> Result<(), RequestError> {
-        Err(error::ExternalError::NotSupported(error::NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_hittest is not supported").into())
     }
 
     fn set_theme(&self, _theme: Option<Theme>) {}

src/platform_impl/apple/appkit/cursor.rs

@@ -11,9 +11,8 @@ use objc2_foundation::{
     NSString,
 };
 
-use super::OsError;
 use crate::cursor::{CursorImage, OnlyCursorImageSource};
-use crate::error::ExternalError;
+use crate::error::RequestError;
 use crate::window::CursorIcon;
 
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
@@ -25,12 +24,12 @@ unsafe impl Send for CustomCursor {}
 unsafe impl Sync for CustomCursor {}
 
 impl CustomCursor {
-    pub(crate) fn new(cursor: OnlyCursorImageSource) -> Result<CustomCursor, ExternalError> {
+    pub(crate) fn new(cursor: OnlyCursorImageSource) -> Result<CustomCursor, RequestError> {
         cursor_from_image(&cursor.0).map(Self)
     }
 }
 
-pub(crate) fn cursor_from_image(cursor: &CursorImage) -> Result<Retained<NSCursor>, ExternalError> {
+pub(crate) fn cursor_from_image(cursor: &CursorImage) -> Result<Retained<NSCursor>, RequestError> {
     let width = cursor.width;
     let height = cursor.height;
 
@@ -48,7 +47,7 @@ pub(crate) fn cursor_from_image(cursor: &CursorImage) -> Result<Retained<NSCurso
             width as isize * 4,
             32,
         )
-    }.ok_or_else(|| ExternalError::Os(os_error!(OsError::CreationError("parent view should be installed in a window"))))?;
+    }.ok_or_else(|| os_error!("parent view should be installed in a window"))?;
     let bitmap_data = unsafe { slice::from_raw_parts_mut(bitmap.bitmapData(), cursor.rgba.len()) };
     bitmap_data.copy_from_slice(&cursor.rgba);
 

src/platform_impl/apple/appkit/event_loop.rs

@@ -29,7 +29,7 @@ use super::event::dummy_event;
 use super::monitor;
 use super::observer::setup_control_flow_observers;
 use crate::application::ApplicationHandler;
-use crate::error::{EventLoopError, ExternalError};
+use crate::error::{EventLoopError, RequestError};
 use crate::event_loop::{
     ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents,
     EventLoopProxy as RootEventLoopProxy, OwnedDisplayHandle as RootOwnedDisplayHandle,
@@ -103,14 +103,14 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: crate::window::WindowAttributes,
-    ) -> Result<Box<dyn crate::window::Window>, crate::error::OsError> {
+    ) -> Result<Box<dyn crate::window::Window>, RequestError> {
         Ok(Box::new(Window::new(self, window_attributes)?))
     }
 
     fn create_custom_cursor(
         &self,
         source: CustomCursorSource,
-    ) -> Result<RootCustomCursor, ExternalError> {
+    ) -> Result<RootCustomCursor, RequestError> {
         Ok(RootCustomCursor { inner: CustomCursor::new(source.inner)? })
     }
 

src/platform_impl/apple/appkit/mod.rs

@@ -14,8 +14,6 @@ mod view;
 mod window;
 mod window_delegate;
 
-use std::fmt;
-
 pub(crate) use self::cursor::CustomCursor as PlatformCustomCursor;
 pub(crate) use self::event::{physicalkey_to_scancode, scancode_to_physicalkey, KeyEventExtra};
 pub(crate) use self::event_loop::{
@@ -50,18 +48,3 @@ impl FingerId {
         FingerId
     }
 }
-
-#[derive(Debug)]
-pub enum OsError {
-    CGError(core_graphics::base::CGError),
-    CreationError(&'static str),
-}
-
-impl fmt::Display for OsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            OsError::CGError(e) => f.pad(&format!("CGError {e}")),
-            OsError::CreationError(e) => f.pad(e),
-        }
-    }
-}

src/platform_impl/apple/appkit/window.rs

@@ -8,7 +8,7 @@ use objc2_foundation::{MainThreadBound, MainThreadMarker, NSObject};
 
 use super::event_loop::ActiveEventLoop;
 use super::window_delegate::WindowDelegate;
-use crate::error::OsError as RootOsError;
+use crate::error::RequestError;
 use crate::monitor::MonitorHandle as CoreMonitorHandle;
 use crate::window::{
     Cursor, Fullscreen, Icon, ImePurpose, Theme, UserAttentionType, Window as CoreWindow,
@@ -25,7 +25,7 @@ impl Window {
     pub(crate) fn new(
         window_target: &ActiveEventLoop,
         attributes: WindowAttributes,
-    ) -> Result<Self, RootOsError> {
+    ) -> Result<Self, RequestError> {
         let mtm = window_target.mtm;
         let delegate =
             autoreleasepool(|_| WindowDelegate::new(&window_target.app_state, attributes, mtm))?;
@@ -111,16 +111,12 @@ impl CoreWindow for Window {
         self.maybe_wait_on_main(|delegate| delegate.reset_dead_keys());
     }
 
-    fn inner_position(
+    fn inner_position(&self) -> Result<dpi::PhysicalPosition<i32>, RequestError> {
-        &self,
+        Ok(self.maybe_wait_on_main(|delegate| delegate.inner_position()))
-    ) -> Result<dpi::PhysicalPosition<i32>, crate::error::NotSupportedError> {
-        self.maybe_wait_on_main(|delegate| delegate.inner_position())
     }
 
-    fn outer_position(
+    fn outer_position(&self) -> Result<dpi::PhysicalPosition<i32>, RequestError> {
-        &self,
+        Ok(self.maybe_wait_on_main(|delegate| delegate.outer_position()))
-    ) -> Result<dpi::PhysicalPosition<i32>, crate::error::NotSupportedError> {
-        self.maybe_wait_on_main(|delegate| delegate.outer_position())
     }
 
     fn set_outer_position(&self, position: Position) {
@@ -275,14 +271,11 @@ impl CoreWindow for Window {
         self.maybe_wait_on_main(|delegate| delegate.set_cursor(cursor));
     }
 
-    fn set_cursor_position(&self, position: Position) -> Result<(), crate::error::ExternalError> {
+    fn set_cursor_position(&self, position: Position) -> Result<(), RequestError> {
         self.maybe_wait_on_main(|delegate| delegate.set_cursor_position(position))
     }
 
-    fn set_cursor_grab(
+    fn set_cursor_grab(&self, mode: crate::window::CursorGrabMode) -> Result<(), RequestError> {
-        &self,
-        mode: crate::window::CursorGrabMode,
-    ) -> Result<(), crate::error::ExternalError> {
         self.maybe_wait_on_main(|delegate| delegate.set_cursor_grab(mode))
     }
 
@@ -290,23 +283,25 @@ impl CoreWindow for Window {
         self.maybe_wait_on_main(|delegate| delegate.set_cursor_visible(visible))
     }
 
-    fn drag_window(&self) -> Result<(), crate::error::ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
-        self.maybe_wait_on_main(|delegate| delegate.drag_window())
+        self.maybe_wait_on_main(|delegate| delegate.drag_window());
+        Ok(())
     }
 
     fn drag_resize_window(
         &self,
         direction: crate::window::ResizeDirection,
-    ) -> Result<(), crate::error::ExternalError> {
+    ) -> Result<(), RequestError> {
-        self.maybe_wait_on_main(|delegate| delegate.drag_resize_window(direction))
+        Ok(self.maybe_wait_on_main(|delegate| delegate.drag_resize_window(direction))?)
     }
 
     fn show_window_menu(&self, position: Position) {
         self.maybe_wait_on_main(|delegate| delegate.show_window_menu(position))
     }
 
-    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), crate::error::ExternalError> {
+    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), RequestError> {
-        self.maybe_wait_on_main(|delegate| delegate.set_cursor_hittest(hittest))
+        self.maybe_wait_on_main(|delegate| delegate.set_cursor_hittest(hittest));
+        Ok(())
     }
 
     fn current_monitor(&self) -> Option<CoreMonitorHandle> {

src/platform_impl/apple/appkit/window_delegate.rs

@@ -33,9 +33,9 @@ use super::monitor::{self, flip_window_screen_coordinates, get_display_id};
 use super::observer::RunLoop;
 use super::view::WinitView;
 use super::window::WinitWindow;
-use super::{ffi, Fullscreen, MonitorHandle, OsError, WindowId};
+use super::{ffi, Fullscreen, MonitorHandle, WindowId};
 use crate::dpi::{LogicalPosition, LogicalSize, PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{ExternalError, NotSupportedError, OsError as RootOsError};
+use crate::error::{NotSupportedError, RequestError};
 use crate::event::{SurfaceSizeWriter, WindowEvent};
 use crate::platform::macos::{OptionAsAlt, WindowExtMacOS};
 use crate::window::{
@@ -677,9 +677,9 @@ impl WindowDelegate {
         app_state: &Rc<AppState>,
         attrs: WindowAttributes,
         mtm: MainThreadMarker,
-    ) -> Result<Retained<Self>, RootOsError> {
+    ) -> Result<Retained<Self>, RequestError> {
         let window = new_window(app_state, &attrs, mtm)
-            .ok_or_else(|| os_error!(OsError::CreationError("couldn't create `NSWindow`")))?;
+            .ok_or_else(|| os_error!("couldn't create `NSWindow`"))?;
 
         #[cfg(feature = "rwh_06")]
         match attrs.parent_window.map(|handle| handle.0) {
@@ -688,9 +688,9 @@ impl WindowDelegate {
                 // Unwrap is fine, since the pointer comes from `NonNull`.
                 let parent_view: Retained<NSView> =
                     unsafe { Retained::retain(handle.ns_view.as_ptr().cast()) }.unwrap();
-                let parent = parent_view.window().ok_or_else(|| {
+                let parent = parent_view
-                    os_error!(OsError::CreationError("parent view should be installed in a window"))
+                    .window()
-                })?;
+                    .ok_or_else(|| os_error!("parent view should be installed in a window"))?;
 
                 // SAFETY: We know that there are no parent -> child -> parent cycles since the only
                 // place in `winit` where we allow making a window a child window is
@@ -925,15 +925,15 @@ impl WindowDelegate {
     #[inline]
     pub fn pre_present_notify(&self) {}
 
-    pub fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    pub fn outer_position(&self) -> PhysicalPosition<i32> {
         let position = flip_window_screen_coordinates(self.window().frame());
-        Ok(LogicalPosition::new(position.x, position.y).to_physical(self.scale_factor()))
+        LogicalPosition::new(position.x, position.y).to_physical(self.scale_factor())
     }
 
-    pub fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    pub fn inner_position(&self) -> PhysicalPosition<i32> {
         let content_rect = self.window().contentRectForFrameRect(self.window().frame());
         let position = flip_window_screen_coordinates(content_rect);
-        Ok(LogicalPosition::new(position.x, position.y).to_physical(self.scale_factor()))
+        LogicalPosition::new(position.x, position.y).to_physical(self.scale_factor())
     }
 
     pub fn set_outer_position(&self, position: Position) {
@@ -1125,18 +1125,18 @@ impl WindowDelegate {
     }
 
     #[inline]
-    pub fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    pub fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), RequestError> {
         let associate_mouse_cursor = match mode {
             CursorGrabMode::Locked => false,
             CursorGrabMode::None => true,
             CursorGrabMode::Confined => {
-                return Err(ExternalError::NotSupported(NotSupportedError::new()))
+                return Err(NotSupportedError::new("confined cursor is not supported").into())
             },
         };
 
         // TODO: Do this for real https://stackoverflow.com/a/40922095/5435443
         CGDisplay::associate_mouse_and_mouse_cursor_position(associate_mouse_cursor)
-            .map_err(|status| ExternalError::Os(os_error!(OsError::CGError(status))))
+            .map_err(|status| os_error!(format!("CGError {status}")).into())
     }
 
     #[inline]
@@ -1154,8 +1154,8 @@ impl WindowDelegate {
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, cursor_position: Position) -> Result<(), ExternalError> {
+    pub fn set_cursor_position(&self, cursor_position: Position) -> Result<(), RequestError> {
-        let physical_window_position = self.inner_position().unwrap();
+        let physical_window_position = self.inner_position();
         let scale_factor = self.scale_factor();
         let window_position = physical_window_position.to_logical::<CGFloat>(scale_factor);
         let logical_cursor_position = cursor_position.to_logical::<CGFloat>(scale_factor);
@@ -1164,33 +1164,31 @@ impl WindowDelegate {
             y: logical_cursor_position.y + window_position.y,
         };
         CGDisplay::warp_mouse_cursor_position(point)
-            .map_err(|e| ExternalError::Os(os_error!(OsError::CGError(e))))?;
+            .map_err(|status| os_error!(format!("CGError {status}")))?;
         CGDisplay::associate_mouse_and_mouse_cursor_position(true)
-            .map_err(|e| ExternalError::Os(os_error!(OsError::CGError(e))))?;
+            .map_err(|status| os_error!(format!("CGError {status}")))?;
 
         Ok(())
     }
 
     #[inline]
-    pub fn drag_window(&self) -> Result<(), ExternalError> {
+    pub fn drag_window(&self) {
         let mtm = MainThreadMarker::from(self);
         let event = NSApplication::sharedApplication(mtm).currentEvent().unwrap();
         self.window().performWindowDragWithEvent(&event);
-        Ok(())
     }
 
     #[inline]
-    pub fn drag_resize_window(&self, _direction: ResizeDirection) -> Result<(), ExternalError> {
+    pub fn drag_resize_window(&self, _direction: ResizeDirection) -> Result<(), NotSupportedError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("drag_resize_window is not supported"))
     }
 
     #[inline]
     pub fn show_window_menu(&self, _position: Position) {}
 
     #[inline]
-    pub fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError> {
+    pub fn set_cursor_hittest(&self, hittest: bool) {
         self.window().setIgnoresMouseEvents(!hittest);
-        Ok(())
     }
 
     pub(crate) fn is_zoomed(&self) -> bool {

src/platform_impl/apple/uikit/event_loop.rs

@@ -25,7 +25,7 @@ use super::super::notification_center::create_observer;
 use super::app_state::{send_occluded_event_for_all_windows, AppState, EventWrapper};
 use super::{app_state, monitor, MonitorHandle};
 use crate::application::ApplicationHandler;
-use crate::error::{EventLoopError, ExternalError, NotSupportedError, OsError};
+use crate::error::{EventLoopError, NotSupportedError, RequestError};
 use crate::event::Event;
 use crate::event_loop::{
     ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents,
@@ -49,15 +49,15 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: crate::window::WindowAttributes,
-    ) -> Result<Box<dyn CoreWindow>, OsError> {
+    ) -> Result<Box<dyn CoreWindow>, RequestError> {
         Ok(Box::new(Window::new(self, window_attributes)?))
     }
 
     fn create_custom_cursor(
         &self,
         _source: CustomCursorSource,
-    ) -> Result<CustomCursor, ExternalError> {
+    ) -> Result<CustomCursor, RequestError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("create_custom_cursor is not supported").into())
     }
 
     fn available_monitors(&self) -> Box<dyn Iterator<Item = RootMonitorHandle>> {

src/platform_impl/apple/uikit/window.rs

@@ -20,7 +20,7 @@ use super::view_controller::WinitViewController;
 use super::{app_state, monitor, ActiveEventLoop, Fullscreen, MonitorHandle};
 use crate::cursor::Cursor;
 use crate::dpi::{LogicalPosition, LogicalSize, PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{ExternalError, NotSupportedError, OsError as RootOsError};
+use crate::error::{NotSupportedError, RequestError};
 use crate::event::{Event, WindowEvent};
 use crate::icon::Icon;
 use crate::monitor::MonitorHandle as CoreMonitorHandle;
@@ -159,20 +159,20 @@ impl Inner {
 
     pub fn pre_present_notify(&self) {}
 
-    pub fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    pub fn inner_position(&self) -> PhysicalPosition<i32> {
         let safe_area = self.safe_area_screen_space();
         let position =
             LogicalPosition { x: safe_area.origin.x as f64, y: safe_area.origin.y as f64 };
         let scale_factor = self.scale_factor();
-        Ok(position.to_physical(scale_factor))
+        position.to_physical(scale_factor)
     }
 
-    pub fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    pub fn outer_position(&self) -> PhysicalPosition<i32> {
         let screen_frame = self.screen_frame();
         let position =
             LogicalPosition { x: screen_frame.origin.x as f64, y: screen_frame.origin.y as f64 };
         let scale_factor = self.scale_factor();
-        Ok(position.to_physical(scale_factor))
+        position.to_physical(scale_factor)
     }
 
     pub fn set_outer_position(&self, physical_position: Position) {
@@ -256,31 +256,31 @@ impl Inner {
         debug!("`Window::set_cursor` ignored on iOS")
     }
 
-    pub fn set_cursor_position(&self, _position: Position) -> Result<(), ExternalError> {
+    pub fn set_cursor_position(&self, _position: Position) -> Result<(), NotSupportedError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_position is not supported"))
     }
 
-    pub fn set_cursor_grab(&self, _: CursorGrabMode) -> Result<(), ExternalError> {
+    pub fn set_cursor_grab(&self, _: CursorGrabMode) -> Result<(), NotSupportedError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_grab is not supported"))
     }
 
     pub fn set_cursor_visible(&self, _visible: bool) {
         debug!("`Window::set_cursor_visible` is ignored on iOS")
     }
 
-    pub fn drag_window(&self) -> Result<(), ExternalError> {
+    pub fn drag_window(&self) -> Result<(), NotSupportedError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("drag_window is not supported"))
     }
 
-    pub fn drag_resize_window(&self, _direction: ResizeDirection) -> Result<(), ExternalError> {
+    pub fn drag_resize_window(&self, _direction: ResizeDirection) -> Result<(), NotSupportedError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("drag_resize_window is not supported"))
     }
 
     #[inline]
     pub fn show_window_menu(&self, _position: Position) {}
 
-    pub fn set_cursor_hittest(&self, _hittest: bool) -> Result<(), ExternalError> {
+    pub fn set_cursor_hittest(&self, _hittest: bool) -> Result<(), NotSupportedError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_hittest is not supported"))
     }
 
     pub fn set_minimized(&self, _minimized: bool) {
@@ -466,7 +466,7 @@ impl Window {
     pub(crate) fn new(
         event_loop: &ActiveEventLoop,
         window_attributes: WindowAttributes,
-    ) -> Result<Window, RootOsError> {
+    ) -> Result<Window, RequestError> {
         let mtm = event_loop.mtm;
 
         if window_attributes.min_surface_size.is_some() {
@@ -606,31 +606,27 @@ impl CoreWindow for Window {
         self.maybe_wait_on_main(|delegate| delegate.reset_dead_keys());
     }
 
-    fn inner_position(
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
-        &self,
+        Ok(self.maybe_wait_on_main(|delegate| delegate.inner_position()))
-    ) -> Result<dpi::PhysicalPosition<i32>, crate::error::NotSupportedError> {
-        self.maybe_wait_on_main(|delegate| delegate.inner_position())
     }
 
-    fn outer_position(
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
-        &self,
+        Ok(self.maybe_wait_on_main(|delegate| delegate.outer_position()))
-    ) -> Result<dpi::PhysicalPosition<i32>, crate::error::NotSupportedError> {
-        self.maybe_wait_on_main(|delegate| delegate.outer_position())
     }
 
     fn set_outer_position(&self, position: Position) {
         self.maybe_wait_on_main(|delegate| delegate.set_outer_position(position));
     }
 
-    fn surface_size(&self) -> dpi::PhysicalSize<u32> {
+    fn surface_size(&self) -> PhysicalSize<u32> {
         self.maybe_wait_on_main(|delegate| delegate.surface_size())
     }
 
-    fn request_surface_size(&self, size: Size) -> Option<dpi::PhysicalSize<u32>> {
+    fn request_surface_size(&self, size: Size) -> Option<PhysicalSize<u32>> {
         self.maybe_wait_on_main(|delegate| delegate.request_surface_size(size))
     }
 
-    fn outer_size(&self) -> dpi::PhysicalSize<u32> {
+    fn outer_size(&self) -> PhysicalSize<u32> {
         self.maybe_wait_on_main(|delegate| delegate.outer_size())
     }
 
@@ -642,7 +638,7 @@ impl CoreWindow for Window {
         self.maybe_wait_on_main(|delegate| delegate.set_max_surface_size(max_size));
     }
 
-    fn surface_resize_increments(&self) -> Option<dpi::PhysicalSize<u32>> {
+    fn surface_resize_increments(&self) -> Option<PhysicalSize<u32>> {
         self.maybe_wait_on_main(|delegate| delegate.surface_resize_increments())
     }
 
@@ -770,38 +766,35 @@ impl CoreWindow for Window {
         self.maybe_wait_on_main(|delegate| delegate.set_cursor(cursor));
     }
 
-    fn set_cursor_position(&self, position: Position) -> Result<(), crate::error::ExternalError> {
+    fn set_cursor_position(&self, position: Position) -> Result<(), RequestError> {
-        self.maybe_wait_on_main(|delegate| delegate.set_cursor_position(position))
+        Ok(self.maybe_wait_on_main(|delegate| delegate.set_cursor_position(position))?)
     }
 
-    fn set_cursor_grab(
+    fn set_cursor_grab(&self, mode: crate::window::CursorGrabMode) -> Result<(), RequestError> {
-        &self,
+        Ok(self.maybe_wait_on_main(|delegate| delegate.set_cursor_grab(mode))?)
-        mode: crate::window::CursorGrabMode,
-    ) -> Result<(), crate::error::ExternalError> {
-        self.maybe_wait_on_main(|delegate| delegate.set_cursor_grab(mode))
     }
 
     fn set_cursor_visible(&self, visible: bool) {
         self.maybe_wait_on_main(|delegate| delegate.set_cursor_visible(visible))
     }
 
-    fn drag_window(&self) -> Result<(), crate::error::ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
-        self.maybe_wait_on_main(|delegate| delegate.drag_window())
+        Ok(self.maybe_wait_on_main(|delegate| delegate.drag_window())?)
     }
 
     fn drag_resize_window(
         &self,
         direction: crate::window::ResizeDirection,
-    ) -> Result<(), crate::error::ExternalError> {
+    ) -> Result<(), RequestError> {
-        self.maybe_wait_on_main(|delegate| delegate.drag_resize_window(direction))
+        Ok(self.maybe_wait_on_main(|delegate| delegate.drag_resize_window(direction))?)
     }
 
     fn show_window_menu(&self, position: Position) {
         self.maybe_wait_on_main(|delegate| delegate.show_window_menu(position))
     }
 
-    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), crate::error::ExternalError> {
+    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), RequestError> {
-        self.maybe_wait_on_main(|delegate| delegate.set_cursor_hittest(hittest))
+        Ok(self.maybe_wait_on_main(|delegate| delegate.set_cursor_hittest(hittest))?)
     }
 
     fn current_monitor(&self) -> Option<CoreMonitorHandle> {

src/platform_impl/linux/mod.rs

@@ -3,25 +3,24 @@
 #[cfg(all(not(x11_platform), not(wayland_platform)))]
 compile_error!("Please select a feature to build for unix: `x11`, `wayland`");
 
+use std::env;
 use std::num::{NonZeroU16, NonZeroU32};
 use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
-use std::sync::Arc;
 use std::time::Duration;
-use std::{env, fmt};
 #[cfg(x11_platform)]
-use std::{ffi::CStr, mem::MaybeUninit, os::raw::*, sync::Mutex};
+use std::{ffi::CStr, mem::MaybeUninit, os::raw::*, sync::Arc, sync::Mutex};
 
 use smol_str::SmolStr;
 
 pub(crate) use self::common::xkb::{physicalkey_to_scancode, scancode_to_physicalkey};
 #[cfg(x11_platform)]
-use self::x11::{X11Error, XConnection, XError, XNotSupported};
+use self::x11::{XConnection, XError, XNotSupported};
 use crate::application::ApplicationHandler;
 pub(crate) use crate::cursor::OnlyCursorImageSource as PlatformCustomCursorSource;
 #[cfg(x11_platform)]
 use crate::dpi::Size;
 use crate::dpi::{PhysicalPosition, PhysicalSize};
-use crate::error::EventLoopError;
+use crate::error::{EventLoopError, NotSupportedError};
 use crate::event_loop::ActiveEventLoop;
 pub(crate) use crate::icon::RgbaIcon as PlatformIcon;
 use crate::keyboard::Key;
@@ -108,31 +107,6 @@ impl Default for PlatformSpecificWindowAttributes {
 pub(crate) static X11_BACKEND: Lazy<Mutex<Result<Arc<XConnection>, XNotSupported>>> =
     Lazy::new(|| Mutex::new(XConnection::new(Some(x_error_callback)).map(Arc::new)));
 
-#[derive(Debug, Clone)]
-pub enum OsError {
-    Misc(&'static str),
-    #[cfg(x11_platform)]
-    XNotSupported(XNotSupported),
-    #[cfg(x11_platform)]
-    XError(Arc<X11Error>),
-    #[cfg(wayland_platform)]
-    WaylandError(Arc<wayland::WaylandError>),
-}
-
-impl fmt::Display for OsError {
-    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        match *self {
-            OsError::Misc(e) => _f.pad(e),
-            #[cfg(x11_platform)]
-            OsError::XNotSupported(ref e) => fmt::Display::fmt(e, _f),
-            #[cfg(x11_platform)]
-            OsError::XError(ref e) => fmt::Display::fmt(e, _f),
-            #[cfg(wayland_platform)]
-            OsError::WaylandError(ref e) => fmt::Display::fmt(e, _f),
-        }
-    }
-}
-
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct WindowId(u64);
 
@@ -411,7 +385,7 @@ impl EventLoop {
                 } else {
                     "neither WAYLAND_DISPLAY nor WAYLAND_SOCKET nor DISPLAY is set."
                 };
-                return Err(EventLoopError::Os(os_error!(OsError::Misc(msg))));
+                return Err(NotSupportedError::new(msg).into());
             },
         };
 
@@ -433,9 +407,7 @@ impl EventLoop {
     fn new_x11_any_thread() -> Result<EventLoop, EventLoopError> {
         let xconn = match X11_BACKEND.lock().unwrap_or_else(|e| e.into_inner()).as_ref() {
             Ok(xconn) => xconn.clone(),
-            Err(err) => {
+            Err(err) => return Err(os_error!(err.clone()).into()),
-                return Err(EventLoopError::Os(os_error!(OsError::XNotSupported(err.clone()))))
-            },
         };
 
         Ok(EventLoop::X(x11::EventLoop::new(xconn)))

src/platform_impl/linux/wayland/event_loop/mod.rs

@@ -8,19 +8,18 @@ use std::sync::atomic::Ordering;
 use std::sync::{Arc, Mutex};
 use std::time::{Duration, Instant};
 
-use sctk::reexports::calloop::Error as CalloopError;
 use sctk::reexports::calloop_wayland_source::WaylandSource;
 use sctk::reexports::client::{globals, Connection, QueueHandle};
 
 use crate::application::ApplicationHandler;
 use crate::cursor::OnlyCursorImage;
 use crate::dpi::LogicalSize;
-use crate::error::{EventLoopError, ExternalError, OsError as RootOsError};
+use crate::error::{EventLoopError, OsError, RequestError};
 use crate::event::{Event, StartCause, SurfaceSizeWriter, WindowEvent};
 use crate::event_loop::{ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents};
 use crate::platform::pump_events::PumpStatus;
 use crate::platform_impl::platform::min_timeout;
-use crate::platform_impl::{OsError, PlatformCustomCursor};
+use crate::platform_impl::PlatformCustomCursor;
 use crate::window::{CustomCursor as RootCustomCursor, CustomCursorSource, Theme};
 
 mod proxy;
@@ -31,7 +30,7 @@ use sink::EventSink;
 
 use super::state::{WindowCompositorUpdate, WinitState};
 use super::window::state::FrameCallbackState;
-use super::{logical_to_physical_rounded, DeviceId, WaylandError, WindowId};
+use super::{logical_to_physical_rounded, DeviceId, WindowId};
 
 type WaylandDispatcher = calloop::Dispatcher<'static, WaylandSource<WinitState>, WinitState>;
 
@@ -61,27 +60,20 @@ pub struct EventLoop {
 
 impl EventLoop {
     pub fn new() -> Result<EventLoop, EventLoopError> {
-        macro_rules! map_err {
+        let connection = Connection::connect_to_env().map_err(|err| os_error!(err))?;
-            ($e:expr, $err:expr) => {
-                $e.map_err(|error| os_error!($err(error).into()))
-            };
-        }
-
-        let connection = map_err!(Connection::connect_to_env(), WaylandError::Connection)?;
 
         let (globals, mut event_queue) =
-            map_err!(globals::registry_queue_init(&connection), WaylandError::Global)?;
+            globals::registry_queue_init(&connection).map_err(|err| os_error!(err))?;
         let queue_handle = event_queue.handle();
 
         let event_loop =
-            map_err!(calloop::EventLoop::<WinitState>::try_new(), WaylandError::Calloop)?;
+            calloop::EventLoop::<WinitState>::try_new().map_err(|err| os_error!(err))?;
 
-        let mut winit_state = WinitState::new(&globals, &queue_handle, event_loop.handle())
+        let mut winit_state = WinitState::new(&globals, &queue_handle, event_loop.handle())?;
-            .map_err(|error| os_error!(error))?;
 
         // NOTE: do a roundtrip after binding the globals to prevent potential
         // races with the server.
-        map_err!(event_queue.roundtrip(&mut winit_state), WaylandError::Dispatch)?;
+        event_queue.roundtrip(&mut winit_state).map_err(|err| os_error!(err))?;
 
         // Register Wayland source.
         let wayland_source = WaylandSource::new(connection.clone(), event_queue);
@@ -97,37 +89,32 @@ impl EventLoop {
                 result
             });
 
-        map_err!(
+        event_loop
-            event_loop.handle().register_dispatcher(wayland_dispatcher.clone()),
+            .handle()
-            WaylandError::Calloop
+            .register_dispatcher(wayland_dispatcher.clone())
-        )?;
+            .map_err(|err| os_error!(err))?;
 
         // Setup the user proxy.
         let (ping, ping_source) = calloop::ping::make_ping().unwrap();
-        let result = event_loop
+        event_loop
             .handle()
             .insert_source(ping_source, move |_, _, winit_state: &mut WinitState| {
                 winit_state.dispatched_events = true;
                 winit_state.proxy_wake_up = true;
             })
-            .map_err(|error| error.error);
+            .map_err(|err| os_error!(err))?;
-        map_err!(result, WaylandError::Calloop)?;
 
         // An event's loop awakener to wake up for window events from winit's windows.
-        let (event_loop_awakener, event_loop_awakener_source) = map_err!(
+        let (event_loop_awakener, event_loop_awakener_source) =
-            calloop::ping::make_ping()
+            calloop::ping::make_ping().map_err(|err| os_error!(err))?;
-                .map_err(|error| CalloopError::OtherError(Box::new(error).into())),
-            WaylandError::Calloop
-        )?;
 
-        let result = event_loop
+        event_loop
             .handle()
             .insert_source(event_loop_awakener_source, move |_, _, winit_state: &mut WinitState| {
                 // Mark that we have something to dispatch.
                 winit_state.dispatched_events = true;
             })
-            .map_err(|error| error.error);
+            .map_err(|err| os_error!(err))?;
-        map_err!(result, WaylandError::Calloop)?;
 
         let active_event_loop = ActiveEventLoop {
             connection: connection.clone(),
@@ -517,14 +504,12 @@ impl EventLoop {
         })
     }
 
-    fn roundtrip(&mut self) -> Result<usize, RootOsError> {
+    fn roundtrip(&mut self) -> Result<usize, OsError> {
         let state = &mut self.active_event_loop.state.get_mut();
 
         let mut wayland_source = self.wayland_dispatcher.as_source_mut();
         let event_queue = wayland_source.queue();
-        event_queue.roundtrip(state).map_err(|error| {
+        event_queue.roundtrip(state).map_err(|err| os_error!(err))
-            os_error!(OsError::WaylandError(Arc::new(WaylandError::Dispatch(error))))
-        })
     }
 
     fn control_flow(&self) -> ControlFlow {
@@ -614,7 +599,7 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_custom_cursor(
         &self,
         cursor: CustomCursorSource,
-    ) -> Result<RootCustomCursor, ExternalError> {
+    ) -> Result<RootCustomCursor, RequestError> {
         Ok(RootCustomCursor {
             inner: PlatformCustomCursor::Wayland(OnlyCursorImage(Arc::from(cursor.inner.0))),
         })
@@ -628,7 +613,7 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: crate::window::WindowAttributes,
-    ) -> Result<Box<dyn crate::window::Window>, RootOsError> {
+    ) -> Result<Box<dyn crate::window::Window>, RequestError> {
         let window = crate::platform_impl::wayland::Window::new(self, window_attributes)?;
         Ok(Box::new(window))
     }

src/platform_impl/linux/wayland/mod.rs

@@ -1,18 +1,14 @@
 //! Winit's Wayland backend.
 
-use std::fmt::Display;
-use std::sync::Arc;
-
 pub use event_loop::{ActiveEventLoop, EventLoop, EventLoopProxy};
 pub use output::{MonitorHandle, VideoModeHandle};
-use sctk::reexports::client::globals::{BindError, GlobalError};
 use sctk::reexports::client::protocol::wl_surface::WlSurface;
-use sctk::reexports::client::{self, ConnectError, DispatchError, Proxy};
+use sctk::reexports::client::Proxy;
 pub use window::Window;
 
 pub(super) use crate::cursor::OnlyCursorImage as CustomCursor;
 use crate::dpi::{LogicalSize, PhysicalSize};
-pub use crate::platform_impl::platform::{OsError, WindowId};
+pub use crate::platform_impl::platform::WindowId;
 
 mod event_loop;
 mod output;
@@ -21,46 +17,6 @@ mod state;
 mod types;
 mod window;
 
-#[derive(Debug)]
-pub enum WaylandError {
-    /// Error connecting to the socket.
-    Connection(ConnectError),
-
-    /// Error binding the global.
-    Global(GlobalError),
-
-    // Bind error.
-    Bind(BindError),
-
-    /// Error during the dispatching the event queue.
-    Dispatch(DispatchError),
-
-    /// Calloop error.
-    Calloop(calloop::Error),
-
-    /// Wayland
-    Wire(client::backend::WaylandError),
-}
-
-impl Display for WaylandError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            WaylandError::Connection(error) => error.fmt(f),
-            WaylandError::Global(error) => error.fmt(f),
-            WaylandError::Bind(error) => error.fmt(f),
-            WaylandError::Dispatch(error) => error.fmt(f),
-            WaylandError::Calloop(error) => error.fmt(f),
-            WaylandError::Wire(error) => error.fmt(f),
-        }
-    }
-}
-
-impl From<WaylandError> for OsError {
-    fn from(value: WaylandError) -> Self {
-        Self::WaylandError(Arc::new(value))
-    }
-}
-
 /// Dummy device id, since Wayland doesn't have device events.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct DeviceId;

src/platform_impl/linux/wayland/state.rs

@@ -21,6 +21,7 @@ use sctk::shm::slot::SlotPool;
 use sctk::shm::{Shm, ShmHandler};
 use sctk::subcompositor::SubcompositorState;
 
+use crate::error::OsError;
 use crate::platform_impl::wayland::event_loop::sink::EventSink;
 use crate::platform_impl::wayland::output::MonitorHandle;
 use crate::platform_impl::wayland::seat::{
@@ -32,8 +33,7 @@ use crate::platform_impl::wayland::types::wp_fractional_scaling::FractionalScali
 use crate::platform_impl::wayland::types::wp_viewporter::ViewporterState;
 use crate::platform_impl::wayland::types::xdg_activation::XdgActivationState;
 use crate::platform_impl::wayland::window::{WindowRequests, WindowState};
-use crate::platform_impl::wayland::{WaylandError, WindowId};
+use crate::platform_impl::wayland::WindowId;
-use crate::platform_impl::OsError;
 
 /// Winit's Wayland state.
 pub struct WinitState {
@@ -126,7 +126,7 @@ impl WinitState {
     ) -> Result<Self, OsError> {
         let registry_state = RegistryState::new(globals);
         let compositor_state =
-            CompositorState::bind(globals, queue_handle).map_err(WaylandError::Bind)?;
+            CompositorState::bind(globals, queue_handle).map_err(|err| os_error!(err))?;
         let subcompositor_state = match SubcompositorState::bind(
             compositor_state.wl_compositor().clone(),
             globals,
@@ -156,7 +156,7 @@ impl WinitState {
                 (None, None)
             };
 
-        let shm = Shm::bind(globals, queue_handle).map_err(WaylandError::Bind)?;
+        let shm = Shm::bind(globals, queue_handle).map_err(|err| os_error!(err))?;
         let custom_cursor_pool = Arc::new(Mutex::new(SlotPool::new(2, &shm).unwrap()));
 
         Ok(Self {
@@ -168,7 +168,7 @@ impl WinitState {
             shm,
             custom_cursor_pool,
 
-            xdg_shell: XdgShell::bind(globals, queue_handle).map_err(WaylandError::Bind)?,
+            xdg_shell: XdgShell::bind(globals, queue_handle).map_err(|err| os_error!(err))?,
             xdg_activation: XdgActivationState::bind(globals, queue_handle).ok(),
 
             windows: Default::default(),

src/platform_impl/linux/wayland/window/mod.rs

@@ -16,13 +16,13 @@ use super::event_loop::sink::EventSink;
 use super::output::MonitorHandle;
 use super::state::WinitState;
 use super::types::xdg_activation::XdgActivationTokenData;
-use super::{ActiveEventLoop, WaylandError, WindowId};
+use super::{ActiveEventLoop, WindowId};
 use crate::dpi::{LogicalSize, PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{ExternalError, NotSupportedError, OsError as RootOsError};
+use crate::error::{NotSupportedError, RequestError};
 use crate::event::{Ime, WindowEvent};
 use crate::event_loop::AsyncRequestSerial;
 use crate::monitor::MonitorHandle as CoreMonitorHandle;
-use crate::platform_impl::{Fullscreen, MonitorHandle as PlatformMonitorHandle, OsError};
+use crate::platform_impl::{Fullscreen, MonitorHandle as PlatformMonitorHandle};
 use crate::window::{
     Cursor, CursorGrabMode, Fullscreen as CoreFullscreen, ImePurpose, ResizeDirection, Theme,
     UserAttentionType, Window as CoreWindow, WindowAttributes, WindowButtons,
@@ -77,7 +77,7 @@ impl Window {
     pub(crate) fn new(
         event_loop_window_target: &ActiveEventLoop,
         attributes: WindowAttributes,
-    ) -> Result<Self, RootOsError> {
+    ) -> Result<Self, RequestError> {
         let queue_handle = event_loop_window_target.queue_handle.clone();
         let mut state = event_loop_window_target.state.borrow_mut();
 
@@ -190,15 +190,11 @@ impl Window {
         let event_queue = wayland_source.queue();
 
         // Do a roundtrip.
-        event_queue.roundtrip(&mut state).map_err(|error| {
+        event_queue.roundtrip(&mut state).map_err(|err| os_error!(err))?;
-            os_error!(OsError::WaylandError(Arc::new(WaylandError::Dispatch(error))))
-        })?;
 
         // XXX Wait for the initial configure to arrive.
         while !window_state.lock().unwrap().is_configured() {
-            event_queue.blocking_dispatch(&mut state).map_err(|error| {
+            event_queue.blocking_dispatch(&mut state).map_err(|err| os_error!(err))?;
-                os_error!(OsError::WaylandError(Arc::new(WaylandError::Dispatch(error))))
-            })?;
         }
 
         // Wake-up event loop, so it'll send initial redraw requested.
@@ -223,10 +219,10 @@ impl Window {
 }
 
 impl Window {
-    pub fn request_activation_token(&self) -> Result<AsyncRequestSerial, NotSupportedError> {
+    pub fn request_activation_token(&self) -> Result<AsyncRequestSerial, RequestError> {
         let xdg_activation = match self.xdg_activation.as_ref() {
             Some(xdg_activation) => xdg_activation,
-            None => return Err(NotSupportedError::new()),
+            None => return Err(NotSupportedError::new("xdg_activation_v1 is not available").into()),
         };
 
         let serial = AsyncRequestSerial::get();
@@ -309,12 +305,14 @@ impl CoreWindow for Window {
         crate::platform_impl::common::xkb::reset_dead_keys()
     }
 
-    fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
-        Err(NotSupportedError::new())
+        Err(NotSupportedError::new("window position information is not available on Wayland")
+            .into())
     }
 
-    fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
-        Err(NotSupportedError::new())
+        Err(NotSupportedError::new("window position information is not available on Wayland")
+            .into())
     }
 
     fn set_outer_position(&self, _position: Position) {
@@ -576,7 +574,7 @@ impl CoreWindow for Window {
         }
     }
 
-    fn set_cursor_position(&self, position: Position) -> Result<(), ExternalError> {
+    fn set_cursor_position(&self, position: Position) -> Result<(), RequestError> {
         let scale_factor = self.scale_factor();
         let position = position.to_logical(scale_factor);
         self.window_state
@@ -587,7 +585,7 @@ impl CoreWindow for Window {
             .map(|_| self.request_redraw())
     }
 
-    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), RequestError> {
         self.window_state.lock().unwrap().set_cursor_grab(mode)
     }
 
@@ -595,11 +593,11 @@ impl CoreWindow for Window {
         self.window_state.lock().unwrap().set_cursor_visible(visible);
     }
 
-    fn drag_window(&self) -> Result<(), ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
         self.window_state.lock().unwrap().drag_window()
     }
 
-    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError> {
+    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), RequestError> {
         self.window_state.lock().unwrap().drag_resize_window(direction)
     }
 
@@ -609,16 +607,14 @@ impl CoreWindow for Window {
         self.window_state.lock().unwrap().show_window_menu(position);
     }
 
-    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError> {
+    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), RequestError> {
         let surface = self.window.wl_surface();
 
         if hittest {
             surface.set_input_region(None);
             Ok(())
         } else {
-            let region = Region::new(&*self.compositor).map_err(|_| {
+            let region = Region::new(&*self.compositor).map_err(|err| os_error!(err))?;
-                ExternalError::Os(os_error!(OsError::Misc("failed to set input region.")))
-            })?;
             region.add(0, 0, 0, 0);
             surface.set_input_region(Some(region.wl_region()));
             Ok(())

src/platform_impl/linux/wayland/window/state.rs

@@ -30,7 +30,7 @@ use wayland_protocols_plasma::blur::client::org_kde_kwin_blur::OrgKdeKwinBlur;
 
 use crate::cursor::CustomCursor as RootCustomCursor;
 use crate::dpi::{LogicalPosition, LogicalSize, PhysicalSize, Size};
-use crate::error::{ExternalError, NotSupportedError};
+use crate::error::{NotSupportedError, RequestError};
 use crate::platform_impl::wayland::logical_to_physical_rounded;
 use crate::platform_impl::wayland::seat::{
     PointerConstraintsState, WinitPointerData, WinitPointerDataExt, ZwpTextInputV3Ext,
@@ -388,7 +388,7 @@ impl WindowState {
     }
 
     /// Start interacting drag resize.
-    pub fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError> {
+    pub fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), RequestError> {
         let xdg_toplevel = self.window.xdg_toplevel();
 
         // TODO(kchibisov) handle touch serials.
@@ -402,7 +402,7 @@ impl WindowState {
     }
 
     /// Start the window drag.
-    pub fn drag_window(&self) -> Result<(), ExternalError> {
+    pub fn drag_window(&self) -> Result<(), RequestError> {
         let xdg_toplevel = self.window.xdg_toplevel();
         // TODO(kchibisov) handle touch serials.
         self.apply_on_pointer(|_, data| {
@@ -799,7 +799,7 @@ impl WindowState {
     }
 
     /// Set the cursor grabbing state on the top-level.
-    pub fn set_cursor_grab(&mut self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    pub fn set_cursor_grab(&mut self, mode: CursorGrabMode) -> Result<(), RequestError> {
         if self.cursor_grab_mode.user_grab_mode == mode {
             return Ok(());
         }
@@ -817,11 +817,15 @@ impl WindowState {
     }
 
     /// Set the grabbing state on the surface.
-    fn set_cursor_grab_inner(&mut self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    fn set_cursor_grab_inner(&mut self, mode: CursorGrabMode) -> Result<(), RequestError> {
         let pointer_constraints = match self.pointer_constraints.as_ref() {
             Some(pointer_constraints) => pointer_constraints,
             None if mode == CursorGrabMode::None => return Ok(()),
-            None => return Err(ExternalError::NotSupported(NotSupportedError::new())),
+            None => {
+                return Err(
+                    NotSupportedError::new("zwp_pointer_constraints is not available").into()
+                )
+            },
         };
 
         // Replace the current mode.
@@ -865,16 +869,17 @@ impl WindowState {
     }
 
     /// Set the position of the cursor.
-    pub fn set_cursor_position(&self, position: LogicalPosition<f64>) -> Result<(), ExternalError> {
+    pub fn set_cursor_position(&self, position: LogicalPosition<f64>) -> Result<(), RequestError> {
         if self.pointer_constraints.is_none() {
-            return Err(ExternalError::NotSupported(NotSupportedError::new()));
+            return Err(NotSupportedError::new("zwp_pointer_constraints is not available").into());
         }
 
         // Position can be set only for locked cursor.
         if self.cursor_grab_mode.current_grab_mode != CursorGrabMode::Locked {
-            return Err(ExternalError::Os(os_error!(crate::platform_impl::OsError::Misc(
+            return Err(NotSupportedError::new(
-                "cursor position can be set only for locked cursor."
+                "cursor position could only be changed for locked pointer",
-            ))));
+            )
+            .into());
         }
 
         self.apply_on_pointer(|_, data| {

src/platform_impl/linux/x11/ime/context.rs

@@ -1,7 +1,8 @@
+use std::error::Error;
 use std::ffi::CStr;
 use std::os::raw::c_short;
 use std::sync::Arc;
-use std::{mem, ptr};
+use std::{fmt, mem, ptr};
 
 use x11_dl::xlib::{XIMCallback, XIMPreeditCaretCallbackStruct, XIMPreeditDrawCallbackStruct};
 
@@ -19,6 +20,19 @@ pub enum ImeContextCreationError {
     Null,
 }
 
+impl fmt::Display for ImeContextCreationError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            ImeContextCreationError::XError(err) => err.fmt(f),
+            ImeContextCreationError::Null => {
+                write!(f, "got null pointer from Xlib without exact reason")
+            },
+        }
+    }
+}
+
+impl Error for ImeContextCreationError {}
+
 /// The callback used by XIM preedit functions.
 type XIMProcNonnull = unsafe extern "C" fn(ffi::XIM, ffi::XPointer, ffi::XPointer);
 

src/platform_impl/linux/x11/mod.rs

@@ -23,7 +23,7 @@ use x11rb::x11_utils::X11Error as LogicalError;
 use x11rb::xcb_ffi::ReplyOrIdError;
 
 use crate::application::ApplicationHandler;
-use crate::error::{EventLoopError, ExternalError, OsError as RootOsError};
+use crate::error::{EventLoopError, RequestError};
 use crate::event::{Event, StartCause, WindowEvent};
 use crate::event_loop::{
     ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents,
@@ -33,7 +33,7 @@ use crate::platform::pump_events::PumpStatus;
 use crate::platform_impl::common::xkb::Context;
 use crate::platform_impl::platform::{min_timeout, WindowId};
 use crate::platform_impl::x11::window::Window;
-use crate::platform_impl::{OsError, OwnedDisplayHandle, PlatformCustomCursor};
+use crate::platform_impl::{OwnedDisplayHandle, PlatformCustomCursor};
 use crate::window::{
     CustomCursor as RootCustomCursor, CustomCursorSource, Theme, Window as CoreWindow,
     WindowAttributes,
@@ -399,9 +399,11 @@ impl EventLoop {
         // `run_on_demand` calls but if they have only just dropped their
         // windows we need to make sure those last requests are sent to the
         // X Server.
-        self.event_processor.target.x_connection().sync_with_server().map_err(|x_err| {
+        self.event_processor
-            EventLoopError::Os(os_error!(OsError::XError(Arc::new(X11Error::Xlib(x_err)))))
+            .target
-        })?;
+            .x_connection()
+            .sync_with_server()
+            .map_err(|x_err| EventLoopError::Os(os_error!(X11Error::Xlib(x_err))))?;
 
         exit
     }
@@ -688,14 +690,14 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: WindowAttributes,
-    ) -> Result<Box<dyn CoreWindow>, RootOsError> {
+    ) -> Result<Box<dyn CoreWindow>, RequestError> {
         Ok(Box::new(Window::new(self, window_attributes)?))
     }
 
     fn create_custom_cursor(
         &self,
         custom_cursor: CustomCursorSource,
-    ) -> Result<RootCustomCursor, ExternalError> {
+    ) -> Result<RootCustomCursor, RequestError> {
         Ok(RootCustomCursor {
             inner: PlatformCustomCursor::X(CustomCursor::new(self, custom_cursor.inner)?),
         })

src/platform_impl/linux/x11/util/cursor.rs

@@ -9,8 +9,8 @@ use x11rb::protocol::xproto;
 
 use super::super::ActiveEventLoop;
 use super::*;
-use crate::error::ExternalError;
+use crate::error::RequestError;
-use crate::platform_impl::{OsError, PlatformCustomCursorSource};
+use crate::platform_impl::PlatformCustomCursorSource;
 use crate::window::CursorIcon;
 
 impl XConnection {
@@ -193,7 +193,7 @@ impl CustomCursor {
     pub(crate) fn new(
         event_loop: &ActiveEventLoop,
         mut cursor: PlatformCustomCursorSource,
-    ) -> Result<CustomCursor, ExternalError> {
+    ) -> Result<CustomCursor, RequestError> {
         // Reverse RGBA order to BGRA.
         cursor.0.rgba.chunks_mut(4).for_each(|chunk| {
             let chunk: &mut [u8; 4] = chunk.try_into().unwrap();
@@ -215,7 +215,7 @@ impl CustomCursor {
                 cursor.0.hotspot_y,
                 &cursor.0.rgba,
             )
-            .map_err(|err| ExternalError::Os(os_error!(OsError::XError(err.into()))))?;
+            .map_err(|err| os_error!(err))?;
 
         Ok(Self { inner: Arc::new(CustomCursorInner { xconn: event_loop.xconn.clone(), cursor }) })
     }

src/platform_impl/linux/x11/window.rs

@@ -22,7 +22,7 @@ use super::{
 };
 use crate::cursor::{Cursor, CustomCursor as RootCustomCursor};
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{ExternalError, NotSupportedError, OsError as RootOsError};
+use crate::error::{NotSupportedError, RequestError};
 use crate::event::{Event, SurfaceSizeWriter, WindowEvent};
 use crate::event_loop::AsyncRequestSerial;
 use crate::platform::x11::WindowType;
@@ -31,8 +31,8 @@ use crate::platform_impl::x11::{
     xinput_fp1616_to_float, MonitorHandle as X11MonitorHandle, WakeSender, X11Error,
 };
 use crate::platform_impl::{
-    common, Fullscreen, MonitorHandle as PlatformMonitorHandle, OsError, PlatformCustomCursor,
+    common, Fullscreen, MonitorHandle as PlatformMonitorHandle, PlatformCustomCursor, PlatformIcon,
-    PlatformIcon, VideoModeHandle as PlatformVideoModeHandle,
+    VideoModeHandle as PlatformVideoModeHandle,
 };
 use crate::window::{
     CursorGrabMode, ImePurpose, ResizeDirection, Theme, UserAttentionType, Window as CoreWindow,
@@ -54,7 +54,7 @@ impl Window {
     pub(crate) fn new(
         event_loop: &ActiveEventLoop,
         attribs: WindowAttributes,
-    ) -> Result<Self, RootOsError> {
+    ) -> Result<Self, RequestError> {
         let window = Arc::new(UnownedWindow::new(event_loop, attribs)?);
         event_loop.windows.borrow_mut().insert(window.id(), Arc::downgrade(&window));
         Ok(Window(window))
@@ -82,11 +82,11 @@ impl CoreWindow for Window {
         common::xkb::reset_dead_keys();
     }
 
-    fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         self.0.inner_position()
     }
 
-    fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         self.0.outer_position()
     }
 
@@ -242,11 +242,11 @@ impl CoreWindow for Window {
         self.0.set_cursor(cursor);
     }
 
-    fn set_cursor_position(&self, position: Position) -> Result<(), ExternalError> {
+    fn set_cursor_position(&self, position: Position) -> Result<(), RequestError> {
         self.0.set_cursor_position(position)
     }
 
-    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), RequestError> {
         self.0.set_cursor_grab(mode)
     }
 
@@ -254,11 +254,11 @@ impl CoreWindow for Window {
         self.0.set_cursor_visible(visible);
     }
 
-    fn drag_window(&self) -> Result<(), ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
         self.0.drag_window()
     }
 
-    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError> {
+    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), RequestError> {
         self.0.drag_resize_window(direction)
     }
 
@@ -266,7 +266,7 @@ impl CoreWindow for Window {
         self.0.show_window_menu(position);
     }
 
-    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError> {
+    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), RequestError> {
         self.0.set_cursor_hittest(hittest)
     }
 
@@ -427,13 +427,9 @@ pub struct UnownedWindow {
     redraw_sender: WakeSender<WindowId>,
     activation_sender: WakeSender<super::ActivationToken>,
 }
-
 macro_rules! leap {
     ($e:expr) => {
-        match $e {
+        $e.map_err(|err| os_error!(err))?
-            Ok(x) => x,
-            Err(err) => return Err(os_error!(OsError::XError(X11Error::from(err).into()))),
-        }
     };
 }
 
@@ -442,7 +438,7 @@ impl UnownedWindow {
     pub(crate) fn new(
         event_loop: &ActiveEventLoop,
         window_attrs: WindowAttributes,
-    ) -> Result<UnownedWindow, RootOsError> {
+    ) -> Result<UnownedWindow, RequestError> {
         let xconn = &event_loop.xconn;
         let atoms = xconn.atoms();
         #[cfg(feature = "rwh_06")]
@@ -527,10 +523,9 @@ impl UnownedWindow {
             match window_attrs.platform_specific.x11.visual_id {
                 Some(vi) => {
                     // Find this specific visual.
-                    let (visualtype, depth) =
+                    let (visualtype, depth) = all_visuals
-                        all_visuals.find(|(visual, _)| visual.visual_id == vi).ok_or_else(
+                        .find(|(visual, _)| visual.visual_id == vi)
-                            || os_error!(OsError::XError(X11Error::NoSuchVisual(vi).into())),
+                        .ok_or_else(|| os_error!(X11Error::NoSuchVisual(vi)))?;
-                        )?;
 
                     (Some(visualtype), depth, true)
                 },
@@ -828,7 +823,7 @@ impl UnownedWindow {
                     &mut supported_ptr,
                 );
                 if supported_ptr == ffi::False {
-                    return Err(os_error!(OsError::Misc("`XkbSetDetectableAutoRepeat` failed")));
+                    return Err(os_error!("`XkbSetDetectableAutoRepeat` failed").into());
                 }
             }
 
@@ -848,14 +843,16 @@ impl UnownedWindow {
 
             // Try to create input context for the window.
             if let Some(ime) = event_loop.ime.as_ref() {
-                let result = ime.borrow_mut().create_context(window.xwindow as ffi::Window, false);
+                ime.borrow_mut()
-                leap!(result);
+                    .create_context(window.xwindow as ffi::Window, false)
+                    .map_err(|err| os_error!(err))?;
             }
 
             // These properties must be set after mapping
             if window_attrs.maximized {
                 leap!(window.set_maximized_inner(window_attrs.maximized)).ignore_error();
             }
+
             if window_attrs.fullscreen.is_some() {
                 if let Some(flusher) =
                     leap!(window
@@ -888,7 +885,7 @@ impl UnownedWindow {
     }
 
     /// Embed this window into a parent window.
-    pub(super) fn embed_window(&self) -> Result<(), RootOsError> {
+    pub(super) fn embed_window(&self) -> Result<(), RequestError> {
         let atoms = self.xconn.atoms();
         leap!(leap!(self.xconn.change_property(
             self.xwindow,
@@ -1500,7 +1497,7 @@ impl UnownedWindow {
     }
 
     #[inline]
-    pub fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    pub fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         let extents = self.shared_state_lock().frame_extents.clone();
         if let Some(extents) = extents {
             let (x, y) = self.inner_position_physical();
@@ -1521,7 +1518,7 @@ impl UnownedWindow {
     }
 
     #[inline]
-    pub fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    pub fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         Ok(self.inner_position_physical().into())
     }
 
@@ -1815,7 +1812,7 @@ impl UnownedWindow {
     }
 
     #[inline]
-    pub fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    pub fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), RequestError> {
         let mut grabbed_lock = self.cursor_grabbed_mode.lock().unwrap();
         if mode == *grabbed_lock {
             return Ok(());
@@ -1829,9 +1826,10 @@ impl UnownedWindow {
             .expect_then_ignore_error("Failed to call `xcb_ungrab_pointer`");
 
         let result = match mode {
-            CursorGrabMode::None => self.xconn.flush_requests().map_err(|err| {
+            CursorGrabMode::None => self
-                ExternalError::Os(os_error!(OsError::XError(X11Error::Xlib(err).into())))
+                .xconn
-            }),
+                .flush_requests()
+                .map_err(|err| RequestError::Os(os_error!(X11Error::Xlib(err)))),
             CursorGrabMode::Confined => {
                 let result = {
                     self.xconn
@@ -1878,10 +1876,12 @@ impl UnownedWindow {
                     },
                     _ => unreachable!(),
                 }
-                .map_err(|err| ExternalError::Os(os_error!(OsError::Misc(err))))
+                .map_err(|err| RequestError::Os(os_error!(err)))
             },
             CursorGrabMode::Locked => {
-                return Err(ExternalError::NotSupported(NotSupportedError::new()));
+                return Err(
+                    NotSupportedError::new("locked cursor is not implemented on X11").into()
+                );
             },
         };
 
@@ -1923,28 +1923,23 @@ impl UnownedWindow {
         self.shared_state_lock().last_monitor.scale_factor
     }
 
-    pub fn set_cursor_position_physical(&self, x: i32, y: i32) -> Result<(), ExternalError> {
+    pub fn set_cursor_position_physical(&self, x: i32, y: i32) -> Result<(), RequestError> {
-        {
+        self.xconn
-            self.xconn
+            .xcb_connection()
-                .xcb_connection()
+            .warp_pointer(x11rb::NONE, self.xwindow, 0, 0, 0, 0, x as _, y as _)
-                .warp_pointer(x11rb::NONE, self.xwindow, 0, 0, 0, 0, x as _, y as _)
+            .map_err(|err| os_error!(X11Error::from(err)))?;
-                .map_err(|e| {
+        self.xconn.flush_requests().map_err(|err| os_error!(X11Error::Xlib(err)))?;
-                    ExternalError::Os(os_error!(OsError::XError(X11Error::from(e).into())))
+        Ok(())
-                })?;
-            self.xconn.flush_requests().map_err(|e| {
-                ExternalError::Os(os_error!(OsError::XError(X11Error::Xlib(e).into())))
-            })
-        }
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, position: Position) -> Result<(), ExternalError> {
+    pub fn set_cursor_position(&self, position: Position) -> Result<(), RequestError> {
         let (x, y) = position.to_physical::<i32>(self.scale_factor()).into();
         self.set_cursor_position_physical(x, y)
     }
 
     #[inline]
-    pub fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError> {
+    pub fn set_cursor_hittest(&self, hittest: bool) -> Result<(), RequestError> {
         let mut rectangles: Vec<Rectangle> = Vec::new();
         if hittest {
             let size = self.surface_size();
@@ -1956,17 +1951,17 @@ impl UnownedWindow {
             })
         }
         let region = RegionWrapper::create_region(self.xconn.xcb_connection(), &rectangles)
-            .map_err(|_e| ExternalError::Ignored)?;
+            .map_err(|_e| RequestError::Ignored)?;
         self.xconn
             .xcb_connection()
             .xfixes_set_window_shape_region(self.xwindow, SK::INPUT, 0, 0, region.region())
-            .map_err(|_e| ExternalError::Ignored)?;
+            .map_err(|_e| RequestError::Ignored)?;
         self.shared_state_lock().cursor_hittest = Some(hittest);
         Ok(())
     }
 
     /// Moves the window while it is being dragged.
-    pub fn drag_window(&self) -> Result<(), ExternalError> {
+    pub fn drag_window(&self) -> Result<(), RequestError> {
         self.drag_initiate(util::MOVERESIZE_MOVE)
     }
 
@@ -1974,7 +1969,7 @@ impl UnownedWindow {
     pub fn show_window_menu(&self, _position: Position) {}
 
     /// Resizes the window while it is being dragged.
-    pub fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError> {
+    pub fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), RequestError> {
         self.drag_initiate(match direction {
             ResizeDirection::East => util::MOVERESIZE_RIGHT,
             ResizeDirection::North => util::MOVERESIZE_TOP,
@@ -1988,13 +1983,13 @@ impl UnownedWindow {
     }
 
     /// Initiates a drag operation while the left mouse button is pressed.
-    fn drag_initiate(&self, action: isize) -> Result<(), ExternalError> {
+    fn drag_initiate(&self, action: isize) -> Result<(), RequestError> {
         let pointer = self
             .xconn
             .query_pointer(self.xwindow, util::VIRTUAL_CORE_POINTER)
-            .map_err(|err| ExternalError::Os(os_error!(OsError::XError(err.into()))))?;
+            .map_err(|err| os_error!(err))?;
 
-        let window = self.inner_position().map_err(ExternalError::NotSupported)?;
+        let window_position = self.inner_position()?;
 
         let atoms = self.xconn.atoms();
         let message = atoms[_NET_WM_MOVERESIZE];
@@ -2005,13 +2000,9 @@ impl UnownedWindow {
         self.xconn
             .xcb_connection()
             .ungrab_pointer(x11rb::CURRENT_TIME)
-            .map_err(|err| {
+            .map_err(|err| os_error!(X11Error::from(err)))?
-                ExternalError::Os(os_error!(OsError::XError(X11Error::from(err).into())))
-            })?
             .ignore_error();
-        self.xconn.flush_requests().map_err(|err| {
+        self.xconn.flush_requests().map_err(|err| os_error!(X11Error::Xlib(err)))?;
-            ExternalError::Os(os_error!(OsError::XError(X11Error::Xlib(err).into())))
-        })?;
         *grabbed_lock = CursorGrabMode::None;
 
         // we keep the lock until we are done
@@ -2025,18 +2016,18 @@ impl UnownedWindow {
                         | xproto::EventMask::SUBSTRUCTURE_NOTIFY,
                 ),
                 [
-                    (window.x + xinput_fp1616_to_float(pointer.win_x) as i32) as u32,
+                    (window_position.x + xinput_fp1616_to_float(pointer.win_x) as i32) as u32,
-                    (window.y + xinput_fp1616_to_float(pointer.win_y) as i32) as u32,
+                    (window_position.y + xinput_fp1616_to_float(pointer.win_y) as i32) as u32,
                     action.try_into().unwrap(),
                     1, // Button 1
                     1,
                 ],
             )
-            .map_err(|err| ExternalError::Os(os_error!(OsError::XError(err.into()))))?;
+            .map_err(|err| os_error!(err))?;
 
-        self.xconn.flush_requests().map_err(|err| {
+        self.xconn.flush_requests().map_err(|err| os_error!(X11Error::Xlib(err)))?;
-            ExternalError::Os(os_error!(OsError::XError(X11Error::Xlib(err).into())))
+
-        })
+        Ok(())
     }
 
     #[inline]
@@ -2135,7 +2126,7 @@ impl UnownedWindow {
     }
 
     #[inline]
-    pub fn request_activation_token(&self) -> Result<AsyncRequestSerial, NotSupportedError> {
+    pub fn request_activation_token(&self) -> Result<AsyncRequestSerial, RequestError> {
         let serial = AsyncRequestSerial::get();
         self.activation_sender.send((self.id(), serial));
         Ok(serial)

src/platform_impl/orbital/event_loop.rs

@@ -12,11 +12,11 @@ use orbclient::{
 use smol_str::SmolStr;
 
 use super::{
-    DeviceId, KeyEventExtra, MonitorHandle, OsError, PlatformSpecificEventLoopAttributes,
+    DeviceId, KeyEventExtra, MonitorHandle, PlatformSpecificEventLoopAttributes, RedoxSocket,
-    RedoxSocket, TimeSocket, WindowId, WindowProperties,
+    TimeSocket, WindowId, WindowProperties,
 };
 use crate::application::ApplicationHandler;
-use crate::error::{EventLoopError, ExternalError, NotSupportedError};
+use crate::error::{EventLoopError, NotSupportedError, RequestError};
 use crate::event::{self, Ime, Modifiers, StartCause};
 use crate::event_loop::{self, ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents};
 use crate::keyboard::{
@@ -284,17 +284,11 @@ impl EventLoop {
         // events.
         let (user_events_sender, user_events_receiver) = mpsc::sync_channel(1);
 
-        let event_socket = Arc::new(
+        let event_socket =
-            RedoxSocket::event()
+            Arc::new(RedoxSocket::event().map_err(|error| os_error!(format!("{error}")))?);
-                .map_err(OsError::new)
-                .map_err(|error| EventLoopError::Os(os_error!(error)))?,
-        );
 
-        let wake_socket = Arc::new(
+        let wake_socket =
-            TimeSocket::open()
+            Arc::new(TimeSocket::open().map_err(|error| os_error!(format!("{error}")))?);
-                .map_err(OsError::new)
-                .map_err(|error| EventLoopError::Os(os_error!(error)))?,
-        );
 
         event_socket
             .write(&syscall::Event {
@@ -302,8 +296,7 @@ impl EventLoop {
                 flags: syscall::EventFlags::EVENT_READ,
                 data: wake_socket.0.fd,
             })
-            .map_err(OsError::new)
+            .map_err(|error| os_error!(format!("{error}")))?;
-            .map_err(|error| EventLoopError::Os(os_error!(error)))?;
 
         Ok(Self {
             windows: Vec::new(),
@@ -731,15 +724,15 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: crate::window::WindowAttributes,
-    ) -> Result<Box<dyn CoreWindow>, crate::error::OsError> {
+    ) -> Result<Box<dyn CoreWindow>, RequestError> {
         Ok(Box::new(Window::new(self, window_attributes)?))
     }
 
     fn create_custom_cursor(
         &self,
         _: CustomCursorSource,
-    ) -> Result<RootCustomCursor, ExternalError> {
+    ) -> Result<RootCustomCursor, RequestError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("create_custom_cursor is not supported").into())
     }
 
     fn available_monitors(&self) -> Box<dyn Iterator<Item = crate::monitor::MonitorHandle>> {

src/platform_impl/orbital/mod.rs

@@ -1,9 +1,7 @@
 #![cfg(target_os = "redox")]
 
-use std::fmt::{self, Display, Formatter};
 use std::num::{NonZeroU16, NonZeroU32};
-use std::str;
+use std::{fmt, str};
-use std::sync::Arc;
 
 use smol_str::SmolStr;
 
@@ -15,6 +13,11 @@ mod event_loop;
 pub use self::window::Window;
 mod window;
 
+pub(crate) use crate::cursor::{
+    NoCustomCursor as PlatformCustomCursor, NoCustomCursor as PlatformCustomCursorSource,
+};
+pub(crate) use crate::icon::NoIcon as PlatformIcon;
+
 struct RedoxSocket {
     fd: usize,
 }
@@ -173,26 +176,6 @@ impl<'a> fmt::Display for WindowProperties<'a> {
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct OsError(Arc<syscall::Error>);
-
-impl OsError {
-    fn new(error: syscall::Error) -> Self {
-        Self(Arc::new(error))
-    }
-}
-
-impl Display for OsError {
-    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result<(), fmt::Error> {
-        self.0.fmt(fmt)
-    }
-}
-
-pub(crate) use crate::cursor::{
-    NoCustomCursor as PlatformCustomCursor, NoCustomCursor as PlatformCustomCursorSource,
-};
-pub(crate) use crate::icon::NoIcon as PlatformIcon;
-
 #[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct MonitorHandle;
 

src/platform_impl/orbital/window.rs

@@ -1,12 +1,10 @@
 use std::collections::VecDeque;
 use std::sync::{Arc, Mutex};
 
-use super::{
+use super::{ActiveEventLoop, MonitorHandle, RedoxSocket, TimeSocket, WindowId, WindowProperties};
-    ActiveEventLoop, MonitorHandle, OsError, RedoxSocket, TimeSocket, WindowId, WindowProperties,
-};
 use crate::cursor::Cursor;
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error;
+use crate::error::{NotSupportedError, RequestError};
 use crate::monitor::MonitorHandle as CoreMonitorHandle;
 use crate::window::{self, Fullscreen, ImePurpose, Window as CoreWindow, WindowId as CoreWindowId};
 
@@ -32,7 +30,7 @@ impl Window {
     pub(crate) fn new(
         el: &ActiveEventLoop,
         attrs: window::WindowAttributes,
-    ) -> Result<Self, error::OsError> {
+    ) -> Result<Self, RequestError> {
         let scale = MonitorHandle.scale_factor();
 
         let (x, y) = if let Some(pos) = attrs.position {
@@ -125,20 +123,17 @@ impl Window {
         })
     }
 
-    fn get_flag(&self, flag: char) -> Result<bool, error::ExternalError> {
+    fn get_flag(&self, flag: char) -> Result<bool, RequestError> {
         let mut buf: [u8; 4096] = [0; 4096];
-        let path = self
+        let path = self.window_socket.fpath(&mut buf).map_err(|err| os_error!(format!("{err}")))?;
-            .window_socket
-            .fpath(&mut buf)
-            .map_err(|err| error::ExternalError::Os(os_error!(OsError::new(err))))?;
         let properties = WindowProperties::new(path);
         Ok(properties.flags.contains(flag))
     }
 
-    fn set_flag(&self, flag: char, value: bool) -> Result<(), error::ExternalError> {
+    fn set_flag(&self, flag: char, value: bool) -> Result<(), RequestError> {
         self.window_socket
             .write(format!("F,{flag},{}", if value { 1 } else { 0 }).as_bytes())
-            .map_err(|err| error::ExternalError::Os(os_error!(OsError::new(err))))?;
+            .map_err(|err| os_error!(format!("{err}")))?;
         Ok(())
     }
 
@@ -204,7 +199,7 @@ impl CoreWindow for Window {
     }
 
     #[inline]
-    fn inner_position(&self) -> Result<PhysicalPosition<i32>, error::NotSupportedError> {
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         let mut buf: [u8; 4096] = [0; 4096];
         let path = self.window_socket.fpath(&mut buf).expect("failed to read properties");
         let properties = WindowProperties::new(path);
@@ -212,7 +207,7 @@ impl CoreWindow for Window {
     }
 
     #[inline]
-    fn outer_position(&self) -> Result<PhysicalPosition<i32>, error::NotSupportedError> {
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         // TODO: adjust for window decorations
         self.inner_position()
     }
@@ -372,12 +367,12 @@ impl CoreWindow for Window {
     fn set_cursor(&self, _: Cursor) {}
 
     #[inline]
-    fn set_cursor_position(&self, _: Position) -> Result<(), error::ExternalError> {
+    fn set_cursor_position(&self, _: Position) -> Result<(), RequestError> {
-        Err(error::ExternalError::NotSupported(error::NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_position is not supported").into())
     }
 
     #[inline]
-    fn set_cursor_grab(&self, mode: window::CursorGrabMode) -> Result<(), error::ExternalError> {
+    fn set_cursor_grab(&self, mode: window::CursorGrabMode) -> Result<(), RequestError> {
         let (grab, relative) = match mode {
             window::CursorGrabMode::None => (false, false),
             window::CursorGrabMode::Confined => (true, false),
@@ -385,10 +380,10 @@ impl CoreWindow for Window {
         };
         self.window_socket
             .write(format!("M,G,{}", if grab { 1 } else { 0 }).as_bytes())
-            .map_err(|err| error::ExternalError::Os(os_error!(OsError::new(err))))?;
+            .map_err(|err| os_error!(format!("{err}")))?;
         self.window_socket
             .write(format!("M,R,{}", if relative { 1 } else { 0 }).as_bytes())
-            .map_err(|err| error::ExternalError::Os(os_error!(OsError::new(err))))?;
+            .map_err(|err| os_error!(format!("{err}")))?;
         Ok(())
     }
 
@@ -398,18 +393,13 @@ impl CoreWindow for Window {
     }
 
     #[inline]
-    fn drag_window(&self) -> Result<(), error::ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
-        self.window_socket
+        self.window_socket.write(b"D").map_err(|err| os_error!(format!("{err}")))?;
-            .write(b"D")
-            .map_err(|err| error::ExternalError::Os(os_error!(OsError::new(err))))?;
         Ok(())
     }
 
     #[inline]
-    fn drag_resize_window(
+    fn drag_resize_window(&self, direction: window::ResizeDirection) -> Result<(), RequestError> {
-        &self,
-        direction: window::ResizeDirection,
-    ) -> Result<(), error::ExternalError> {
         let arg = match direction {
             window::ResizeDirection::East => "R",
             window::ResizeDirection::North => "T",
@@ -422,7 +412,7 @@ impl CoreWindow for Window {
         };
         self.window_socket
             .write(format!("D,{}", arg).as_bytes())
-            .map_err(|err| error::ExternalError::Os(os_error!(OsError::new(err))))?;
+            .map_err(|err| os_error!(format!("{err}")))?;
         Ok(())
     }
 
@@ -430,8 +420,8 @@ impl CoreWindow for Window {
     fn show_window_menu(&self, _position: Position) {}
 
     #[inline]
-    fn set_cursor_hittest(&self, _hittest: bool) -> Result<(), error::ExternalError> {
+    fn set_cursor_hittest(&self, _hittest: bool) -> Result<(), RequestError> {
-        Err(error::ExternalError::NotSupported(error::NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_hittest is not supported").into())
     }
 
     #[inline]

src/platform_impl/web/event_loop/window_target.rs

@@ -11,7 +11,7 @@ use super::event::DeviceId;
 use super::runner::{EventWrapper, WeakShared};
 use super::window::WindowId;
 use super::{backend, runner, EventLoopProxy};
-use crate::error::{ExternalError, NotSupportedError};
+use crate::error::{NotSupportedError, RequestError};
 use crate::event::{
     DeviceId as RootDeviceId, ElementState, Event, FingerId as RootFingerId, KeyEvent, Touch,
     TouchPhase, WindowEvent,
@@ -606,7 +606,10 @@ impl ActiveEventLoop {
     }
 
     pub(crate) fn has_multiple_screens(&self) -> Result<bool, NotSupportedError> {
-        self.runner.monitor().is_extended().ok_or(NotSupportedError::new())
+        self.runner
+            .monitor()
+            .is_extended()
+            .ok_or(NotSupportedError::new("has_multiple_screens is not supported"))
     }
 
     pub(crate) fn request_detailed_monitor_permission(&self) -> MonitorPermissionFuture {
@@ -631,7 +634,7 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: crate::window::WindowAttributes,
-    ) -> Result<Box<dyn crate::window::Window>, crate::error::OsError> {
+    ) -> Result<Box<dyn crate::window::Window>, RequestError> {
         let window = Window::new(self, window_attributes)?;
         Ok(Box::new(window))
     }
@@ -639,7 +642,7 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_custom_cursor(
         &self,
         source: CustomCursorSource,
-    ) -> Result<RootCustomCursor, ExternalError> {
+    ) -> Result<RootCustomCursor, RequestError> {
         Ok(RootCustomCursor { inner: CustomCursor::new(self, source.inner) })
     }
 

src/platform_impl/web/mod.rs

@@ -37,7 +37,6 @@ pub(crate) use cursor::{
     CustomCursorSource as PlatformCustomCursorSource,
 };
 
-pub use self::error::OsError;
 pub use self::event::{DeviceId, FingerId};
 pub(crate) use self::event_loop::{
     ActiveEventLoop, EventLoop, EventLoopProxy, OwnedDisplayHandle,

src/platform_impl/web/web_sys/canvas.rs

@@ -22,10 +22,10 @@ use super::media_query_handle::MediaQueryListHandle;
 use super::pointer::PointerHandler;
 use super::{event, fullscreen, ButtonsState, ResizeScaleHandle};
 use crate::dpi::{LogicalPosition, PhysicalPosition, PhysicalSize};
-use crate::error::OsError as RootOE;
+use crate::error::RequestError;
 use crate::event::{Force, MouseButton, MouseScrollDelta, SurfaceSizeWriter};
 use crate::keyboard::{Key, KeyLocation, ModifiersState, PhysicalKey};
-use crate::platform_impl::{Fullscreen, OsError};
+use crate::platform_impl::Fullscreen;
 use crate::window::{WindowAttributes, WindowId as RootWindowId};
 
 #[allow(dead_code)]
@@ -83,13 +83,13 @@ impl Canvas {
         navigator: Navigator,
         document: Document,
         attr: WindowAttributes,
-    ) -> Result<Self, RootOE> {
+    ) -> Result<Self, RequestError> {
         let canvas = match attr.platform_specific.canvas.map(Arc::try_unwrap) {
             Some(Ok(canvas)) => canvas.into_inner(main_thread),
             Some(Err(canvas)) => canvas.get(main_thread).clone(),
             None => document
                 .create_element("canvas")
-                .map_err(|_| os_error!(OsError("Failed to create canvas element".to_owned())))?
+                .map_err(|_| os_error!("Failed to create canvas element"))?
                 .unchecked_into(),
         };
 
@@ -109,7 +109,7 @@ impl Canvas {
         if attr.platform_specific.focusable {
             canvas
                 .set_attribute("tabindex", "0")
-                .map_err(|_| os_error!(OsError("Failed to set a tabindex".to_owned())))?;
+                .map_err(|_| os_error!("Failed to set a tabindex"))?;
         }
 
         let style = Style::new(&window, &canvas);

src/platform_impl/web/window.rs

@@ -9,7 +9,7 @@ use super::monitor::MonitorHandler;
 use super::r#async::Dispatcher;
 use super::{backend, lock, ActiveEventLoop};
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{ExternalError, NotSupportedError, OsError as RootOE};
+use crate::error::{NotSupportedError, RequestError};
 use crate::icon::Icon;
 use crate::monitor::MonitorHandle as RootMonitorHandle;
 use crate::window::{
@@ -31,7 +31,10 @@ pub struct Inner {
 }
 
 impl Window {
-    pub(crate) fn new(target: &ActiveEventLoop, attr: WindowAttributes) -> Result<Self, RootOE> {
+    pub(crate) fn new(
+        target: &ActiveEventLoop,
+        attr: WindowAttributes,
+    ) -> Result<Self, RequestError> {
         let id = target.generate_id();
 
         let window = target.runner.window();
@@ -106,13 +109,13 @@ impl RootWindow for Window {
         // Not supported
     }
 
-    fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         // Note: the canvas element has no window decorations, so this is equal to `outer_position`.
         self.outer_position()
     }
 
-    fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
-        self.inner.queue(|inner| Ok(inner.canvas.position().to_physical(inner.scale_factor())))
+        Ok(self.inner.queue(|inner| inner.canvas.position().to_physical(inner.scale_factor())))
     }
 
     fn set_outer_position(&self, position: Position) {
@@ -315,12 +318,12 @@ impl RootWindow for Window {
         self.inner.dispatch(move |inner| inner.canvas.cursor.set_cursor(cursor))
     }
 
-    fn set_cursor_position(&self, _: Position) -> Result<(), ExternalError> {
+    fn set_cursor_position(&self, _: Position) -> Result<(), RequestError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_position is not supported").into())
     }
 
-    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), RequestError> {
-        self.inner.queue(|inner| {
+        Ok(self.inner.queue(|inner| {
             match mode {
                 CursorGrabMode::None => inner.canvas.document().exit_pointer_lock(),
                 CursorGrabMode::Locked => lock::request_pointer_lock(
@@ -329,30 +332,30 @@ impl RootWindow for Window {
                     inner.canvas.raw(),
                 ),
                 CursorGrabMode::Confined => {
-                    return Err(ExternalError::NotSupported(NotSupportedError::new()))
+                    return Err(NotSupportedError::new("confined cursor mode is not supported"))
                 },
             }
 
             Ok(())
-        })
+        })?)
     }
 
     fn set_cursor_visible(&self, visible: bool) {
         self.inner.dispatch(move |inner| inner.canvas.cursor.set_cursor_visible(visible))
     }
 
-    fn drag_window(&self) -> Result<(), ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("drag_window is not supported").into())
     }
 
-    fn drag_resize_window(&self, _: ResizeDirection) -> Result<(), ExternalError> {
+    fn drag_resize_window(&self, _: ResizeDirection) -> Result<(), RequestError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("drag_resize_window is not supported").into())
     }
 
     fn show_window_menu(&self, _: Position) {}
 
-    fn set_cursor_hittest(&self, _: bool) -> Result<(), ExternalError> {
+    fn set_cursor_hittest(&self, _: bool) -> Result<(), RequestError> {
-        Err(ExternalError::NotSupported(NotSupportedError::new()))
+        Err(NotSupportedError::new("set_cursor_hittest is not supported").into())
     }
 
     fn current_monitor(&self) -> Option<RootMonitorHandle> {

src/platform_impl/windows/event_loop.rs

@@ -56,7 +56,7 @@ use super::window::set_skip_taskbar;
 use super::SelectedCursor;
 use crate::application::ApplicationHandler;
 use crate::dpi::{PhysicalPosition, PhysicalSize};
-use crate::error::{EventLoopError, ExternalError, OsError};
+use crate::error::{EventLoopError, RequestError};
 use crate::event::{
     Event, FingerId as RootFingerId, Force, Ime, RawKeyEvent, SurfaceSizeWriter, Touch, TouchPhase,
     WindowEvent,
@@ -521,14 +521,14 @@ impl RootActiveEventLoop for ActiveEventLoop {
     fn create_window(
         &self,
         window_attributes: WindowAttributes,
-    ) -> Result<Box<dyn CoreWindow>, OsError> {
+    ) -> Result<Box<dyn CoreWindow>, RequestError> {
         Ok(Box::new(Window::new(self, window_attributes)?))
     }
 
     fn create_custom_cursor(
         &self,
         source: CustomCursorSource,
-    ) -> Result<RootCustomCursor, ExternalError> {
+    ) -> Result<RootCustomCursor, RequestError> {
         Ok(RootCustomCursor { inner: WinCursor::new(&source.inner.0)? })
     }
 

src/platform_impl/windows/icon.rs

@@ -17,7 +17,7 @@ use windows_sys::Win32::UI::WindowsAndMessaging::{
 use super::util;
 use crate::cursor::CursorImage;
 use crate::dpi::PhysicalSize;
-use crate::error::ExternalError;
+use crate::error::RequestError;
 use crate::icon::*;
 
 impl Pixel {
@@ -179,7 +179,7 @@ impl Default for SelectedCursor {
 pub struct WinCursor(pub(super) Arc<RaiiCursor>);
 
 impl WinCursor {
-    pub(crate) fn new(image: &CursorImage) -> Result<Self, ExternalError> {
+    pub(crate) fn new(image: &CursorImage) -> Result<Self, RequestError> {
         let mut bgra = image.rgba.clone();
         bgra.chunks_exact_mut(4).for_each(|chunk| chunk.swap(0, 2));
 
@@ -189,16 +189,16 @@ impl WinCursor {
         unsafe {
             let hdc_screen = GetDC(0);
             if hdc_screen == 0 {
-                return Err(ExternalError::Os(os_error!(io::Error::last_os_error())));
+                return Err(os_error!(io::Error::last_os_error()).into());
             }
             let hbm_color = CreateCompatibleBitmap(hdc_screen, w, h);
             ReleaseDC(0, hdc_screen);
             if hbm_color == 0 {
-                return Err(ExternalError::Os(os_error!(io::Error::last_os_error())));
+                return Err(os_error!(io::Error::last_os_error()).into());
             }
             if SetBitmapBits(hbm_color, bgra.len() as u32, bgra.as_ptr() as *const c_void) == 0 {
                 DeleteObject(hbm_color);
-                return Err(ExternalError::Os(os_error!(io::Error::last_os_error())));
+                return Err(os_error!(io::Error::last_os_error()).into());
             };
 
             // Mask created according to https://learn.microsoft.com/en-us/windows/win32/api/wingdi/nf-wingdi-createbitmap#parameters
@@ -206,7 +206,7 @@ impl WinCursor {
             let hbm_mask = CreateBitmap(w, h, 1, 1, mask_bits.as_ptr() as *const _);
             if hbm_mask == 0 {
                 DeleteObject(hbm_color);
-                return Err(ExternalError::Os(os_error!(io::Error::last_os_error())));
+                return Err(os_error!(io::Error::last_os_error()).into());
             }
 
             let icon_info = ICONINFO {
@@ -221,7 +221,7 @@ impl WinCursor {
             DeleteObject(hbm_color);
             DeleteObject(hbm_mask);
             if handle == 0 {
-                return Err(ExternalError::Os(os_error!(io::Error::last_os_error())));
+                return Err(os_error!(io::Error::last_os_error()).into());
             }
 
             Ok(Self(Arc::new(RaiiCursor { handle })))

src/platform_impl/windows/mod.rs

@@ -103,8 +103,6 @@ fn wrap_device_id(id: u32) -> RootDeviceId {
     RootDeviceId(DeviceId(id))
 }
 
-pub type OsError = std::io::Error;
-
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub struct KeyEventExtra {
     pub text_with_all_modifiers: Option<SmolStr>,

src/platform_impl/windows/window.rs

@@ -47,7 +47,7 @@ use windows_sys::Win32::UI::WindowsAndMessaging::{
 
 use crate::cursor::Cursor;
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{ExternalError, NotSupportedError, OsError as RootOsError};
+use crate::error::{NotSupportedError, RequestError};
 use crate::icon::Icon;
 use crate::monitor::MonitorHandle as CoreMonitorHandle;
 use crate::platform::windows::{BackdropType, Color, CornerPreference};
@@ -89,7 +89,7 @@ impl Window {
     pub(crate) fn new(
         event_loop: &ActiveEventLoop,
         w_attr: WindowAttributes,
-    ) -> Result<Window, RootOsError> {
+    ) -> Result<Window, RequestError> {
         // We dispatch an `init` function because of code style.
         // First person to remove the need for cloning here gets a cookie!
         //
@@ -411,7 +411,7 @@ impl CoreWindow for Window {
 
     fn pre_present_notify(&self) {}
 
-    fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         util::WindowArea::Outer
             .get_rect(self.hwnd())
             .map(|rect| Ok(PhysicalPosition::new(rect.left, rect.top)))
@@ -421,7 +421,7 @@ impl CoreWindow for Window {
             )
     }
 
-    fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError> {
         let mut position: POINT = unsafe { mem::zeroed() };
         if unsafe { ClientToScreen(self.hwnd(), &mut position) } == false.into() {
             panic!(
@@ -588,12 +588,12 @@ impl CoreWindow for Window {
         }
     }
 
-    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), ExternalError> {
+    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), RequestError> {
         let confine = match mode {
             CursorGrabMode::None => false,
             CursorGrabMode::Confined => true,
             CursorGrabMode::Locked => {
-                return Err(ExternalError::NotSupported(NotSupportedError::new()))
+                return Err(NotSupportedError::new("locked cursor is not supported").into())
             },
         };
 
@@ -608,9 +608,10 @@ impl CoreWindow for Window {
                 .unwrap()
                 .mouse
                 .set_cursor_flags(window, |f| f.set(CursorFlags::GRABBED, confine))
-                .map_err(|e| ExternalError::Os(os_error!(e)));
+                .map_err(|err| os_error!(err).into());
             let _ = tx.send(result);
         });
+
         rx.recv().unwrap()
     }
 
@@ -636,23 +637,23 @@ impl CoreWindow for Window {
         self.window_state_lock().scale_factor
     }
 
-    fn set_cursor_position(&self, position: Position) -> Result<(), ExternalError> {
+    fn set_cursor_position(&self, position: Position) -> Result<(), RequestError> {
         let scale_factor = self.scale_factor();
         let (x, y) = position.to_physical::<i32>(scale_factor).into();
 
         let mut point = POINT { x, y };
         unsafe {
             if ClientToScreen(self.hwnd(), &mut point) == false.into() {
-                return Err(ExternalError::Os(os_error!(io::Error::last_os_error())));
+                return Err(os_error!(io::Error::last_os_error()).into());
             }
             if SetCursorPos(point.x, point.y) == false.into() {
-                return Err(ExternalError::Os(os_error!(io::Error::last_os_error())));
+                return Err(os_error!(io::Error::last_os_error()).into());
             }
         }
         Ok(())
     }
 
-    fn drag_window(&self) -> Result<(), ExternalError> {
+    fn drag_window(&self) -> Result<(), RequestError> {
         unsafe {
             self.handle_os_dragging(HTCAPTION as WPARAM);
         }
@@ -660,7 +661,7 @@ impl CoreWindow for Window {
         Ok(())
     }
 
-    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError> {
+    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), RequestError> {
         unsafe {
             self.handle_os_dragging(match direction {
                 ResizeDirection::East => HTRIGHT,
@@ -683,7 +684,7 @@ impl CoreWindow for Window {
         }
     }
 
-    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError> {
+    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), RequestError> {
         let window = self.window;
         let window_state = Arc::clone(&self.window_state);
         self.thread_executor.execute_in_thread(move || {
@@ -1249,7 +1250,7 @@ impl<'a> InitData<'a> {
 unsafe fn init(
     attributes: WindowAttributes,
     event_loop: &ActiveEventLoop,
-) -> Result<Window, RootOsError> {
+) -> Result<Window, RequestError> {
     let title = util::encode_wide(&attributes.title);
 
     let class_name = util::encode_wide(&attributes.platform_specific.class_name);
@@ -1332,7 +1333,7 @@ unsafe fn init(
     }
 
     if handle == 0 {
-        return Err(os_error!(io::Error::last_os_error()));
+        return Err(os_error!(io::Error::last_os_error()).into());
     }
 
     // If the handle is non-null, then window creation must have succeeded, which means

src/window.rs

@@ -8,7 +8,7 @@ use serde::{Deserialize, Serialize};
 
 pub use crate::cursor::{BadImage, Cursor, CustomCursor, CustomCursorSource, MAX_CURSOR_SIZE};
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
-use crate::error::{ExternalError, NotSupportedError};
+use crate::error::RequestError;
 pub use crate::icon::{BadIcon, Icon};
 use crate::monitor::{MonitorHandle, VideoModeHandle};
 use crate::platform_impl::{self, PlatformSpecificWindowAttributes};
@@ -601,10 +601,10 @@ pub trait Window: AsAny + Send + Sync {
     ///   coordinate system.
     /// - **Web:** Returns the top-left coordinates relative to the viewport. _Note: this returns
     ///   the same value as [`Window::outer_position`]._
-    /// - **Android / Wayland:** Always returns [`NotSupportedError`].
+    /// - **Android / Wayland:** Always returns [`RequestError::NotSupported`].
     ///
     /// [safe area]: https://developer.apple.com/documentation/uikit/uiview/2891103-safeareainsets?language=objc
-    fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError>;
+    fn inner_position(&self) -> Result<PhysicalPosition<i32>, RequestError>;
 
     /// Returns the position of the top-left hand corner of the window relative to the
     /// top-left hand corner of the desktop.
@@ -621,8 +621,8 @@ pub trait Window: AsAny + Send + Sync {
     /// - **iOS:** Returns the top left coordinates of the window in the screen space coordinate
     ///   system.
     /// - **Web:** Returns the top-left coordinates relative to the viewport.
-    /// - **Android / Wayland:** Always returns [`NotSupportedError`].
+    /// - **Android / Wayland:** Always returns [`RequestError::NotSupported`].
-    fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError>;
+    fn outer_position(&self) -> Result<PhysicalPosition<i32>, RequestError>;
 
     /// Modifies the position of the window.
     ///
@@ -1160,8 +1160,8 @@ pub trait Window: AsAny + Send + Sync {
     /// ## Platform-specific
     ///
     /// - **Wayland**: Cursor must be in [`CursorGrabMode::Locked`].
-    /// - **iOS / Android / Web / Orbital:** Always returns an [`ExternalError::NotSupported`].
+    /// - **iOS / Android / Web / Orbital:** Always returns an [`RequestError::NotSupported`].
-    fn set_cursor_position(&self, position: Position) -> Result<(), ExternalError>;
+    fn set_cursor_position(&self, position: Position) -> Result<(), RequestError>;
 
     /// Set grabbing [mode][CursorGrabMode] on the cursor preventing it from leaving the window.
     ///
@@ -1178,7 +1178,7 @@ pub trait Window: AsAny + Send + Sync {
     ///     .unwrap();
     /// # }
     /// ```
-    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), ExternalError>;
+    fn set_cursor_grab(&self, mode: CursorGrabMode) -> Result<(), RequestError>;
 
     /// Modifies the cursor's visibility.
     ///
@@ -1204,8 +1204,8 @@ pub trait Window: AsAny + Send + Sync {
     /// - **X11:** Un-grabs the cursor.
     /// - **Wayland:** Requires the cursor to be inside the window to be dragged.
     /// - **macOS:** May prevent the button release event to be triggered.
-    /// - **iOS / Android / Web:** Always returns an [`ExternalError::NotSupported`].
+    /// - **iOS / Android / Web:** Always returns an [`RequestError::NotSupported`].
-    fn drag_window(&self) -> Result<(), ExternalError>;
+    fn drag_window(&self) -> Result<(), RequestError>;
 
     /// Resizes the window with the left mouse button until the button is released.
     ///
@@ -1214,9 +1214,9 @@ pub trait Window: AsAny + Send + Sync {
     ///
     /// ## Platform-specific
     ///
-    /// - **macOS:** Always returns an [`ExternalError::NotSupported`]
+    /// - **macOS:** Always returns an [`RequestError::NotSupported`]
-    /// - **iOS / Android / Web:** Always returns an [`ExternalError::NotSupported`].
+    /// - **iOS / Android / Web:** Always returns an [`RequestError::NotSupported`].
-    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError>;
+    fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), RequestError>;
 
     /// Show [window menu] at a specified position .
     ///
@@ -1237,8 +1237,8 @@ pub trait Window: AsAny + Send + Sync {
     ///
     /// ## Platform-specific
     ///
-    /// - **iOS / Android / Web / Orbital:** Always returns an [`ExternalError::NotSupported`].
+    /// - **iOS / Android / Web / Orbital:** Always returns an [`RequestError::NotSupported`].
-    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError>;
+    fn set_cursor_hittest(&self, hittest: bool) -> Result<(), RequestError>;
 
     /// Returns the monitor on which the window currently resides.
     ///
@@ -1345,8 +1345,8 @@ pub enum CursorGrabMode {
     ///
     /// ## Platform-specific
     ///
-    /// - **macOS:** Not implemented. Always returns [`ExternalError::NotSupported`] for now.
+    /// - **macOS:** Not implemented. Always returns [`RequestError::NotSupported`] for now.
-    /// - **iOS / Android / Web:** Always returns an [`ExternalError::NotSupported`].
+    /// - **iOS / Android / Web:** Always returns an [`RequestError::NotSupported`].
     Confined,
 
     /// The cursor is locked inside the window area to the certain position.
@@ -1356,9 +1356,9 @@ pub enum CursorGrabMode {
     ///
     /// ## Platform-specific
     ///
-    /// - **X11 / Windows:** Not implemented. Always returns [`ExternalError::NotSupported`] for
+    /// - **X11 / Windows:** Not implemented. Always returns [`RequestError::NotSupported`] for
     ///   now.
-    /// - **iOS / Android:** Always returns an [`ExternalError::NotSupported`].
+    /// - **iOS / Android:** Always returns an [`RequestError::NotSupported`].
     Locked,
 }