Use tracing macros in examples instead of println!

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

Author: madsmtm

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

@@ -388,8 +388,7 @@ impl LayoutCache {
                 let key = match unicode {
                     ToUnicodeResult::Str(str) => Key::Character(SmolStr::new(str)),
                     ToUnicodeResult::Dead(dead_char) => {
-                        // println!("{:?} - {:?} produced dead {:?}", key_code, mod_state,
-                        // dead_char);
+                        // trace!("{:?} - {:?} produced dead {:?}", key_code, mod_state, dead_char);
                         Key::Dead(dead_char)
                     },
                     ToUnicodeResult::None => {

winit-x11/src/util/mod.rs

@@ -66,15 +66,15 @@ 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");
+        // tracing::trace!("XFlush");
         // This isn't necessarily a useful time to check for errors (since our request hasn't
         // necessarily been processed yet)
         self.check_errors()
     }
 
     pub fn sync_with_server(&self) -> Result<(), XError> {
         unsafe { (self.xlib.XSync)(self.display, ffi::False) };
-        // println!("XSync");
+        // tracing::trace!("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.")
 }