Switch to let-else and ok_or() to reduce nesting

src/backends/kms.rs

@@ -43,16 +43,15 @@ impl<D: HasDisplayHandle + ?Sized> ContextInterface<D> for Arc<KmsDisplayImpl<D>
     where
         D: Sized,
     {
-        let fd = match display.display_handle()?.as_raw() {
-            RawDisplayHandle::Drm(drm) => drm.fd,
-            _ => return Err(InitError::Unsupported(display)),
+        let RawDisplayHandle::Drm(drm) = display.display_handle()?.as_raw() else {
+            return Err(InitError::Unsupported(display));
         };
-        if fd == -1 {
+        if drm.fd == -1 {
             return Err(SoftBufferError::IncompleteDisplayHandle.into());
         }
 
         // SAFETY: Invariants guaranteed by the user.
-        let fd = unsafe { BorrowedFd::borrow_raw(fd) };
+        let fd = unsafe { BorrowedFd::borrow_raw(drm.fd) };
 
         Ok(Arc::new(KmsDisplayImpl {
             fd,
@@ -142,13 +141,12 @@ impl<D: HasDisplayHandle + ?Sized, W: HasWindowHandle> SurfaceInterface<D, W> fo
     /// Create a new KMS backend.
     fn new(window: W, display: &Arc<KmsDisplayImpl<D>>) -> Result<Self, InitError<W>> {
         // Make sure that the window handle is valid.
-        let plane_handle = match window.window_handle()?.as_raw() {
-            RawWindowHandle::Drm(drm) => match NonZeroU32::new(drm.plane) {
-                Some(handle) => plane::Handle::from(handle),
-                None => return Err(SoftBufferError::IncompleteWindowHandle.into()),
-            },
-            _ => return Err(InitError::Unsupported(window)),
+        let RawWindowHandle::Drm(drm) = window.window_handle()?.as_raw() else {
+            return Err(InitError::Unsupported(window));
         };
+        let plane_handle =
+            NonZeroU32::new(drm.plane).ok_or(SoftBufferError::IncompleteWindowHandle)?;
+        let plane_handle = plane::Handle::from(plane_handle);
 
         let plane_info = display
             .get_plane(plane_handle)

src/backends/orbital.rs

@@ -135,9 +135,8 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for Orbital
 
     fn new(window: W, _display: &D) -> Result<Self, InitError<W>> {
         let raw = window.window_handle()?.as_raw();
-        let handle = match raw {
-            RawWindowHandle::Orbital(handle) => handle,
-            _ => return Err(InitError::Unsupported(window)),
+        let RawWindowHandle::Orbital(handle) = raw else {
+            return Err(InitError::Unsupported(window));
         };
 
         Ok(Self {

src/backends/wayland/mod.rs

@@ -45,12 +45,11 @@ impl<D: HasDisplayHandle + ?Sized> ContextInterface<D> for Arc<WaylandDisplayImp
         D: Sized,
     {
         let raw = display.display_handle()?.as_raw();
-        let wayland_handle = match raw {
-            RawDisplayHandle::Wayland(w) => w.display,
-            _ => return Err(InitError::Unsupported(display)),
+        let RawDisplayHandle::Wayland(w) = raw else {
+            return Err(InitError::Unsupported(display));
         };
 
-        let backend = unsafe { Backend::from_foreign_display(wayland_handle.as_ptr().cast()) };
+        let backend = unsafe { Backend::from_foreign_display(w.display.as_ptr().cast()) };
         let conn = Connection::from_backend(backend);
         let (globals, event_queue) =
             registry_queue_init(&conn).swbuf_err("Failed to make round trip to server")?;
@@ -159,15 +158,14 @@ impl<D: HasDisplayHandle + ?Sized, W: HasWindowHandle> SurfaceInterface<D, W>
     fn new(window: W, display: &Arc<WaylandDisplayImpl<D>>) -> Result<Self, InitError<W>> {
         // Get the raw Wayland window.
         let raw = window.window_handle()?.as_raw();
-        let wayland_handle = match raw {
-            RawWindowHandle::Wayland(w) => w.surface,
-            _ => return Err(InitError::Unsupported(window)),
+        let RawWindowHandle::Wayland(w) = raw else {
+            return Err(InitError::Unsupported(window));
         };
 
         let surface_id = unsafe {
             ObjectId::from_ptr(
                 wl_surface::WlSurface::interface(),
-                wayland_handle.as_ptr().cast(),
+                w.surface.as_ptr().cast(),
             )
         }
         .swbuf_err("Failed to create proxy for surface ID.")?;

src/backends/web.rs

@@ -26,10 +26,9 @@ pub struct WebDisplayImpl<D> {
 impl<D: HasDisplayHandle> ContextInterface<D> for WebDisplayImpl<D> {
     fn new(display: D) -> Result<Self, InitError<D>> {
         let raw = display.display_handle()?.as_raw();
-        match raw {
-            RawDisplayHandle::Web(..) => {}
-            _ => return Err(InitError::Unsupported(display)),
-        }
+        let RawDisplayHandle::Web(..) = raw else {
+            return Err(InitError::Unsupported(display));
+        };
 
         let document = web_sys::window()
             .swbuf_err("`Window` is not present in this runtime")?

src/backends/win32.rs

@@ -216,9 +216,8 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for Win32Im
     /// Create a new `Win32Impl` from a `Win32WindowHandle`.
     fn new(window: W, _display: &D) -> Result<Self, crate::error::InitError<W>> {
         let raw = window.window_handle()?.as_raw();
-        let handle = match raw {
-            RawWindowHandle::Win32(handle) => handle,
-            _ => return Err(crate::InitError::Unsupported(window)),
+        let RawWindowHandle::Win32(handle) = raw else {
+            return Err(crate::InitError::Unsupported(window));
         };
 
         // Get the handle to the device context.

src/backends/x11.rs

@@ -196,10 +196,8 @@ impl<D: HasDisplayHandle + ?Sized, W: HasWindowHandle> SurfaceInterface<D, W> fo
         let window_handle = match raw {
             RawWindowHandle::Xcb(xcb) => xcb,
             RawWindowHandle::Xlib(xlib) => {
-                let window = match NonZeroU32::new(xlib.window as u32) {
-                    Some(window) => window,
-                    None => return Err(SoftBufferError::IncompleteWindowHandle.into()),
-                };
+                let window = NonZeroU32::new(xlib.window as u32)
+                    .ok_or(SoftBufferError::IncompleteWindowHandle)?;
                 let mut xcb_window_handle = XcbWindowHandle::new(window);
                 xcb_window_handle.visual_id = NonZeroU32::new(xlib.visual_id as u32);
                 xcb_window_handle
@@ -705,26 +703,21 @@ impl ShmSegment {
         id.set_len(size as u64)?;
 
         // Map the shared memory to our file descriptor space.
-        let ptr = unsafe {
-            let ptr = mm::mmap(
+        let ptr = NonNull::new(unsafe {
+            mm::mmap(
                 null_mut(),
                 size,
                 mm::ProtFlags::READ | mm::ProtFlags::WRITE,
                 mm::MapFlags::SHARED,
                 &id,
                 0,
-            )?;
-
-            match NonNull::new(ptr.cast()) {
-                Some(ptr) => ptr,
-                None => {
-                    return Err(io::Error::new(
-                        io::ErrorKind::Other,
-                        "unexpected null when mapping SHM segment",
-                    ));
-                }
-            }
-        };
+            )?
+        })
+        .ok_or(io::Error::new(
+            io::ErrorKind::Other,
+            "unexpected null when mapping SHM segment",
+        ))?
+        .cast();
 
         Ok(Self {
             id,