Only show id clash warnings in debug builds by default (#2930)

Change with `egui_ctx.options_mut(|opt| opt.warn_on_id_clash = true);`

crates/egui/src/context.rs

@@ -463,7 +463,13 @@ impl Context {
     /// because that's where the warning will be painted. If you don't know what size to pick, just pick [`Vec2::ZERO`].
     pub fn check_for_id_clash(&self, id: Id, new_rect: Rect, what: &str) {
         let prev_rect = self.frame_state_mut(move |state| state.used_ids.insert(id, new_rect));
-        if let Some(prev_rect) = prev_rect {
+
+        if !self.options(|opt| opt.warn_on_id_clash) {
+            return;
+        }
+
+        let Some(prev_rect) = prev_rect else { return };
+
         // it is ok to reuse the same ID for e.g. a frame around a widget,
         // or to check for interaction with the same widget twice:
         if prev_rect.expand(0.1).contains_rect(new_rect)
@@ -525,7 +531,6 @@ impl Context {
             show_error(new_rect, format!("Second use of {} ID {}", what, id_str));
         }
     }
-    }
 
     // ---------------------------------------------------------------------
 

crates/egui/src/frame_state.rs

@@ -21,7 +21,6 @@ pub(crate) struct AccessKitFrameState {
 #[derive(Clone)]
 pub(crate) struct FrameState {
     /// All [`Id`]s that were used this frame.
-    /// Used to debug [`Id`] clashes of widgets.
     pub(crate) used_ids: IdMap<Rect>,
 
     /// Starts off as the screen_rect, shrinks as panels are added.

crates/egui/src/memory.rs

@@ -121,6 +121,11 @@ pub struct Options {
     /// This can lead to fewer texture operations, but may use up the texture atlas quicker
     /// if you are changing [`Style::text_styles`], of have a lot of text styles.
     pub preload_font_glyphs: bool,
+
+    /// Check reusing of [`Id`]s, and show a visual warning on screen when one is found.
+    ///
+    /// By default this is `true` in debug builds.
+    pub warn_on_id_clash: bool,
 }
 
 impl Default for Options {
@@ -130,6 +135,7 @@ impl Default for Options {
             tessellation_options: Default::default(),
             screen_reader: false,
             preload_font_glyphs: true,
+            warn_on_id_clash: cfg!(debug_assertions),
         }
     }
 }

crates/egui_demo_lib/src/demo/tests.rs

@@ -48,6 +48,9 @@ impl super::Demo for IdTest {
 
 impl super::View for IdTest {
     fn ui(&mut self, ui: &mut egui::Ui) {
+        // Make sure the warnings are on (by default they are only on in debug builds).
+        ui.ctx().options_mut(|opt| opt.warn_on_id_clash = true);
+
         ui.heading("Name collision example");
 
         ui.label("\