Make Application and Sandbox return a Result

winit/src/application.rs

@@ -1,7 +1,9 @@
 //! Create interactive, native cross-platform applications.
+use crate::conversion;
+use crate::mouse;
 use crate::{
-    conversion, mouse, Clipboard, Color, Command, Debug, Executor, Mode, Proxy,
-    Runtime, Settings, Size, Subscription,
+    Clipboard, Color, Command, Debug, Error, Executor, Mode, Proxy, Runtime,
+    Settings, Size, Subscription,
 };
 use iced_graphics::window;
 use iced_graphics::Viewport;
@@ -108,7 +110,8 @@ pub trait Application: Program {
 pub fn run<A, E, C>(
     settings: Settings<A::Flags>,
     compositor_settings: C::Settings,
-) where
+) -> Result<(), Error>
+where
     A: Application + 'static,
     E: Executor + 'static,
     C: window::Compositor<Renderer = A::Renderer> + 'static,
@@ -123,7 +126,7 @@ pub fn run<A, E, C>(
 
     let event_loop = EventLoop::with_user_event();
     let mut runtime = {
-        let executor = E::new().expect("Create executor");
+        let executor = E::new().map_err(Error::ExecutorCreationFailed)?;
         let proxy = Proxy::new(event_loop.create_proxy());
 
         Runtime::new(executor, proxy)
@@ -145,7 +148,7 @@ pub fn run<A, E, C>(
         .window
         .into_builder(&title, mode, event_loop.primary_monitor())
         .build(&event_loop)
-        .expect("Open window");
+        .map_err(Error::WindowCreationFailed)?;
 
     let clipboard = Clipboard::new(&window);
     // TODO: Encode cursor availability in the type-system
@@ -160,7 +163,7 @@ pub fn run<A, E, C>(
     );
     let mut resized = false;
 
-    let (mut compositor, mut renderer) = C::new(compositor_settings);
+    let (mut compositor, mut renderer) = C::new(compositor_settings)?;
 
     let surface = compositor.create_surface(&window);
 

winit/src/error.rs

@@ -0,0 +1,27 @@
+use iced_futures::futures;
+
+/// An error that occurred while running an application.
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    /// The futures executor could not be created.
+    #[error("the futures executor could not be created")]
+    ExecutorCreationFailed(futures::io::Error),
+
+    /// The application window could not be created.
+    #[error("the application window could not be created")]
+    WindowCreationFailed(winit::error::OsError),
+
+    /// A suitable graphics adapter or device could not be found.
+    #[error("a suitable graphics adapter or device could not be found")]
+    GraphicsAdapterNotFound,
+}
+
+impl From<iced_graphics::Error> for Error {
+    fn from(error: iced_graphics::Error) -> Error {
+        match error {
+            iced_graphics::Error::AdapterNotFound => {
+                Error::GraphicsAdapterNotFound
+            }
+        }
+    }
+}

winit/src/lib.rs

@@ -30,11 +30,13 @@ pub mod conversion;
 pub mod settings;
 
 mod clipboard;
+mod error;
 mod mode;
 mod proxy;
 
 pub use application::Application;
 pub use clipboard::Clipboard;
+pub use error::Error;
 pub use mode::Mode;
 pub use proxy::Proxy;
 pub use settings::Settings;