examples: Use tracing macros instead of println!

This allows the examples to work a bit better in WASM and on iOS.

clippy.toml

@@ -1,4 +1,11 @@
 # Using allow-invalid because this is platform-specific code
+disallowed-macros = [
+    { path = "std::print", reason = "works badly on web", replacement = "tracing::info" },
+    { path = "std::println", reason = "works badly on web", replacement = "tracing::info" },
+    { path = "std::eprint", reason = "works badly on web", replacement = "tracing::error" },
+    { path = "std::eprintln", reason = "works badly on web", replacement = "tracing::error" },
+    { path = "std::dbg", reason = "leftover debugging aid, remove it or use tracing" },
+]
 disallowed-methods = [
     { allow-invalid = true, path = "objc2_app_kit::NSView::visibleRect", reason = "We expose a render target to the user, and visibility is not really relevant to that (and can break if you don't use the rectangle position as well). Use `frame` instead." },
     { allow-invalid = true, path = "objc2_app_kit::NSWindow::setFrameTopLeftPoint", reason = "Not sufficient when working with Winit's coordinate system, use `flip_window_screen_coordinates` instead" },

winit-common/src/event_handler.rs

@@ -79,6 +79,10 @@ impl EventHandler {
                         // Allowed, happens if the handler was cleared manually
                         // elsewhere (such as in `applicationWillTerminate:`).
                     },
+                    // We use `eprintln!` here over `tracing::error!`, since we're going to abort
+                    // immediately after this, and it'd be annoying for the user if they didn't get
+                    // any feedback on that if they don't have a tracing subscriber.
+                    #[allow(clippy::disallowed_macros)]
                     Err(_) => {
                         // Note: This is not expected to ever happen, this
                         // module generally controls the `RefCell`, and

winit-win32/src/keyboard_layout.rs

@@ -387,11 +387,7 @@ impl LayoutCache {
                 let unicode = Self::to_unicode_string(&key_state, vk, scancode, locale_id);
                 let key = match unicode {
                     ToUnicodeResult::Str(str) => Key::Character(SmolStr::new(str)),
-                    ToUnicodeResult::Dead(dead_char) => {
+                    ToUnicodeResult::Dead(dead_char) => Key::Dead(dead_char),
-                        // println!("{:?} - {:?} produced dead {:?}", key_code, mod_state,
-                        // dead_char);
-                        Key::Dead(dead_char)
-                    },
                     ToUnicodeResult::None => {
                         let has_alt = mod_state.contains(WindowsModifiers::ALT);
                         let has_ctrl = mod_state.contains(WindowsModifiers::CONTROL);

winit-x11/src/util/mod.rs

@@ -66,7 +66,6 @@ impl XConnection {
     // All util functions that abstract an async function will return a `Flusher`.
     pub fn flush_requests(&self) -> Result<(), XError> {
         unsafe { (self.xlib.XFlush)(self.display) };
-        // println!("XFlush");
         // This isn't necessarily a useful time to check for errors (since our request hasn't
         // necessarily been processed yet)
         self.check_errors()
@@ -74,7 +73,6 @@ impl XConnection {
 
     pub fn sync_with_server(&self) -> Result<(), XError> {
         unsafe { (self.xlib.XSync)(self.display, ffi::False) };
-        // println!("XSync");
         self.check_errors()
     }
 }

winit/build.rs

@@ -1,7 +1,9 @@
 use cfg_aliases::cfg_aliases;
 
+// Only relevant for examples and Winit, our usage of println! is fine here.
+#[allow(clippy::disallowed_macros)]
 fn main() {
-    // The script doesn't depend on our code.
+    // Dummy invocation to enable change-tracking in build scripts.
     println!("cargo:rerun-if-changed=build.rs");
 
     // Setup cfg aliases.

winit/examples/child_window.rs

@@ -3,6 +3,7 @@
 fn main() -> Result<(), impl std::error::Error> {
     use std::collections::HashMap;
 
+    use tracing::info;
     use winit::application::ApplicationHandler;
     use winit::dpi::{LogicalPosition, LogicalSize, Position};
     use winit::event::{ElementState, KeyEvent, WindowEvent};
@@ -38,7 +39,7 @@ fn main() -> Result<(), impl std::error::Error> {
                 .with_position(Position::Logical(LogicalPosition::new(0.0, 0.0)))
                 .with_surface_size(LogicalSize::new(640.0f32, 480.0f32));
             let window = event_loop.create_window(attributes).unwrap();
-            println!("Parent window id: {:?})", window.id());
+            info!("Parent window id: {:?})", window.id());
             self.parent_window_id = Some(window.id());
 
             self.windows.insert(window.id(), WindowData::new(window, 0xffbbbbbb));
@@ -56,12 +57,12 @@ fn main() -> Result<(), impl std::error::Error> {
                     event_loop.exit();
                 },
                 WindowEvent::PointerEntered { device_id: _, .. } => {
-                    // On x11, println when the cursor entered in a window even if the child window
+                    // On x11, log when the cursor entered in a window even if the child window
                     // is created by some key inputs.
                     // the child windows are always placed at (0, 0) with size (200, 200) in the
                     // parent window, so we also can see this log when we move
                     // the cursor around (200, 200) in parent window.
-                    println!("cursor entered in the window {window_id:?}");
+                    info!("cursor entered in the window {window_id:?}");
                 },
                 WindowEvent::KeyboardInput {
                     event: KeyEvent { state: ElementState::Pressed, .. },
@@ -75,7 +76,7 @@ fn main() -> Result<(), impl std::error::Error> {
                     let child_window =
                         spawn_child_window(parent_window.window.as_ref(), event_loop, child_index);
                     let child_id = child_window.id();
-                    println!("Child window created with id: {child_id:?}");
+                    info!("Child window created with id: {child_id:?}");
                     self.windows.insert(child_id, WindowData::new(child_window, child_color));
                 },
                 WindowEvent::RedrawRequested => {

winit/examples/control_flow.rs

@@ -4,7 +4,7 @@ use std::thread;
 #[cfg(not(web_platform))]
 use std::time;
 
-use ::tracing::{info, warn};
+use tracing::{info, warn};
 #[cfg(web_platform)]
 use web_time as time;
 use winit::application::ApplicationHandler;

winit/examples/dnd.rs

@@ -1,5 +1,6 @@
 use std::error::Error;
 
+use tracing::info;
 use winit::application::ApplicationHandler;
 use winit::event::WindowEvent;
 use winit::event_loop::{ActiveEventLoop, EventLoop};
@@ -49,7 +50,7 @@ impl ApplicationHandler for Application {
             | WindowEvent::DragEntered { .. }
             | WindowEvent::DragMoved { .. }
             | WindowEvent::DragDropped { .. } => {
-                println!("{event:?}");
+                info!("{event:?}");
             },
             WindowEvent::RedrawRequested => {
                 let window = self.window.as_ref().unwrap();

winit/examples/ime.rs

@@ -76,7 +76,7 @@ impl ApplicationHandler for App {
         self.window = match event_loop.create_window(window_attributes) {
             Ok(window) => Some(window),
             Err(err) => {
-                eprintln!("error creating window: {err}");
+                error!("error creating window: {err}");
                 event_loop.exit();
                 return;
             },
@@ -346,7 +346,7 @@ fn main() -> Result<(), Box<dyn Error>> {
 
     let event_loop = EventLoop::new()?;
 
-    println!(
+    info!(
         r#"This showcases the use of an input method engine (IME) by emulating a text edit field.
 Use CTRL+i to toggle IME support.
 Use CTRL+p to cycle content purpose values.

winit/examples/pump_events.rs

@@ -7,6 +7,7 @@ fn main() -> std::process::ExitCode {
     use std::thread::sleep;
     use std::time::Duration;
 
+    use tracing::info;
     use winit::application::ApplicationHandler;
     use winit::event::WindowEvent;
     use winit::event_loop::pump_events::{EventLoopExtPumpEvents, PumpStatus};
@@ -33,7 +34,7 @@ fn main() -> std::process::ExitCode {
             _window_id: WindowId,
             event: WindowEvent,
         ) {
-            println!("{event:?}");
+            info!("{event:?}");
 
             let window = match self.window.as_ref() {
                 Some(window) => window,
@@ -69,12 +70,12 @@ fn main() -> std::process::ExitCode {
         //
         // Since `pump_events` doesn't block it will be important to
         // throttle the loop in the app somehow.
-        println!("Update()");
+        info!("Update()");
         sleep(Duration::from_millis(16));
     }
 }
 
 #[cfg(any(ios_platform, web_platform, orbital_platform))]
 fn main() {
-    println!("This platform doesn't support pump_events.");
+    panic!("This platform doesn't support pump_events.")
 }

winit/examples/run_on_demand.rs

@@ -5,6 +5,7 @@
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     use std::time::Duration;
 
+    use tracing::info;
     use winit::application::ApplicationHandler;
     use winit::event::WindowEvent;
     use winit::event_loop::run_on_demand::EventLoopExtRunOnDemand;
@@ -44,10 +45,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             event: WindowEvent,
         ) {
             if event == WindowEvent::Destroyed && self.window_id == Some(window_id) {
-                println!(
+                info!("Window {} Destroyed", self.idx);
-                    "--------------------------------------------------------- Window {} Destroyed",
-                    self.idx
-                );
                 self.window_id = None;
                 event_loop.exit();
                 return;
@@ -60,11 +58,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
             match event {
                 WindowEvent::CloseRequested => {
-                    println!(
+                    info!("Window {} CloseRequested", self.idx);
-                        "--------------------------------------------------------- Window {} \
-                         CloseRequested",
-                        self.idx
-                    );
                     fill::cleanup_window(window.as_ref());
                     self.window = None;
                 },
@@ -83,13 +77,13 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut app = App { idx: 1, ..Default::default() };
     event_loop.run_app_on_demand(&mut app)?;
 
-    println!("--------------------------------------------------------- Finished first loop");
+    info!("Finished first loop");
-    println!("--------------------------------------------------------- Waiting 5 seconds");
+    info!("Waiting 5 seconds");
     std::thread::sleep(Duration::from_secs(5));
 
     app.idx += 1;
     event_loop.run_app_on_demand(&mut app)?;
-    println!("--------------------------------------------------------- Finished second loop");
+    info!("Finished second loop");
     Ok(())
 }
 
@@ -101,5 +95,5 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     orbital_platform
 )))]
 fn main() {
-    println!("This example is not supported on this platform");
+    panic!("This example is not supported on this platform")
 }

winit/examples/util/tracing.rs

@@ -23,3 +23,6 @@ pub fn init() {
         )
         .init();
 }
+
+#[allow(unused_imports)]
+pub use ::tracing::*;

winit/examples/window.rs

@@ -2,6 +2,7 @@
 
 use std::error::Error;
 
+use tracing::{error, info};
 use winit::application::ApplicationHandler;
 use winit::event::WindowEvent;
 use winit::event_loop::{ActiveEventLoop, EventLoop};
@@ -29,7 +30,7 @@ impl ApplicationHandler for App {
         self.window = match event_loop.create_window(window_attributes) {
             Ok(window) => Some(window),
             Err(err) => {
-                eprintln!("error creating window: {err}");
+                error!("error creating window: {err}");
                 event_loop.exit();
                 return;
             },
@@ -37,10 +38,10 @@ impl ApplicationHandler for App {
     }
 
     fn window_event(&mut self, event_loop: &dyn ActiveEventLoop, _: WindowId, event: WindowEvent) {
-        println!("{event:?}");
+        info!("{event:?}");
         match event {
             WindowEvent::CloseRequested => {
-                println!("Close was requested; stopping");
+                info!("Close was requested; stopping");
                 event_loop.exit();
             },
             WindowEvent::SurfaceResized(_) => {

winit/examples/x11_embed.rs

@@ -66,6 +66,5 @@ fn main() -> Result<(), Box<dyn Error>> {
 
 #[cfg(not(x11_platform))]
 fn main() -> Result<(), Box<dyn Error>> {
-    println!("This example is only supported on X11 platforms.");
+    panic!("This example is only supported on X11 platforms.")
-    Ok(())
 }