Add Default for all schedule labels (#18731)

# Objective

In `bevy_enhanced_input`, I'm trying to associate `Actions` with a
schedule. I can do this via an associated type on a trait, but there's
no way to construct the associated label except by requiring a `Default`
implementation. However, Bevy labels don't implement `Default`.

## Solution

Add `Default` to all built-in labels. I think it should be useful in
general.

crates/bevy_app/src/main_schedule.rs

@@ -52,31 +52,31 @@ use bevy_ecs::{
 /// [`RenderPlugin`]: https://docs.rs/bevy/latest/bevy/render/struct.RenderPlugin.html
 /// [`PipelinedRenderingPlugin`]: https://docs.rs/bevy/latest/bevy/render/pipelined_rendering/struct.PipelinedRenderingPlugin.html
 /// [`SubApp`]: crate::SubApp
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct Main;
 
 /// The schedule that runs before [`Startup`].
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct PreStartup;
 
 /// The schedule that runs once when the app starts.
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct Startup;
 
 /// The schedule that runs once after [`Startup`].
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct PostStartup;
 
 /// Runs first in the schedule.
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct First;
 
 /// The schedule that contains logic that must run before [`Update`]. For example, a system that reads raw keyboard
@@ -87,7 +87,7 @@ pub struct First;
 /// [`PreUpdate`] abstracts out "pre work implementation details".
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct PreUpdate;
 
 /// Runs the [`FixedMain`] schedule in a loop according until all relevant elapsed time has been "consumed".
@@ -99,21 +99,21 @@ pub struct PreUpdate;
 /// [`RunFixedMainLoop`] will *not* be parallelized between each other.
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct RunFixedMainLoop;
 
 /// Runs first in the [`FixedMain`] schedule.
 ///
 /// See the [`FixedMain`] schedule for details on how fixed updates work.
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct FixedFirst;
 
 /// The schedule that contains logic that must run before [`FixedUpdate`].
 ///
 /// See the [`FixedMain`] schedule for details on how fixed updates work.
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct FixedPreUpdate;
 
 /// The schedule that contains most gameplay logic, which runs at a fixed rate rather than every render frame.
@@ -128,7 +128,7 @@ pub struct FixedPreUpdate;
 /// See the [`Update`] schedule for examples of systems that *should not* use this schedule.
 /// See the [`FixedMain`] schedule for details on how fixed updates work.
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct FixedUpdate;
 
 /// The schedule that runs after the [`FixedUpdate`] schedule, for reacting
@@ -136,14 +136,14 @@ pub struct FixedUpdate;
 ///
 /// See the [`FixedMain`] schedule for details on how fixed updates work.
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct FixedPostUpdate;
 
 /// The schedule that runs last in [`FixedMain`]
 ///
 /// See the [`FixedMain`] schedule for details on how fixed updates work.
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct FixedLast;
 
 /// The schedule that contains systems which only run after a fixed period of time has elapsed.
@@ -155,7 +155,7 @@ pub struct FixedLast;
 /// See [this example](https://github.com/bevyengine/bevy/blob/latest/examples/time/time.rs).
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct FixedMain;
 
 /// The schedule that contains any app logic that must run once per render frame.
@@ -168,13 +168,13 @@ pub struct FixedMain;
 ///
 /// See the [`FixedUpdate`] schedule for examples of systems that *should not* use this schedule.
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct Update;
 
 /// The schedule that contains scene spawning.
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct SpawnScene;
 
 /// The schedule that contains logic that must run after [`Update`]. For example, synchronizing "local transforms" in a hierarchy
@@ -185,13 +185,13 @@ pub struct SpawnScene;
 /// [`PostUpdate`] abstracts out "implementation details" from users defining systems in [`Update`].
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct PostUpdate;
 
 /// Runs last in the schedule.
 ///
 /// See the [`Main`] schedule for some details about how schedules are run.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct Last;
 
 /// Animation system set. This exists in [`PostUpdate`].

crates/bevy_remote/src/lib.rs

@@ -558,7 +558,7 @@ impl Plugin for RemotePlugin {
 }
 
 /// Schedule that contains all systems to process Bevy Remote Protocol requests
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct RemoteLast;
 
 /// The systems sets of the [`RemoteLast`] schedule.

crates/bevy_render/src/lib.rs

@@ -190,7 +190,7 @@ pub enum RenderSet {
 }
 
 /// The main render schedule.
-#[derive(ScheduleLabel, Debug, Hash, PartialEq, Eq, Clone)]
+#[derive(ScheduleLabel, Debug, Hash, PartialEq, Eq, Clone, Default)]
 pub struct Render;
 
 impl Render {
@@ -246,7 +246,7 @@ impl Render {
 ///
 /// This schedule is run on the main world, but its buffers are not applied
 /// until it is returned to the render world.
-#[derive(ScheduleLabel, PartialEq, Eq, Debug, Clone, Hash)]
+#[derive(ScheduleLabel, PartialEq, Eq, Debug, Clone, Hash, Default)]
 pub struct ExtractSchedule;
 
 /// The simulation [`World`] of the application, stored as a resource.

crates/bevy_state/src/state/transitions.rs

@@ -12,13 +12,13 @@ use super::{resources::State, states::States};
 /// The label of a [`Schedule`] that **only** runs whenever [`State<S>`] enters the provided state.
 ///
 /// This schedule ignores identity transitions.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct OnEnter<S: States>(pub S);
 
 /// The label of a [`Schedule`] that **only** runs whenever [`State<S>`] exits the provided state.
 ///
 /// This schedule ignores identity transitions.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct OnExit<S: States>(pub S);
 
 /// The label of a [`Schedule`] that **only** runs whenever [`State<S>`]
@@ -27,7 +27,7 @@ pub struct OnExit<S: States>(pub S);
 /// Systems added to this schedule are always ran *after* [`OnExit`], and *before* [`OnEnter`].
 ///
 /// This schedule will run on identity transitions.
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct OnTransition<S: States> {
     /// The state being exited.
     pub exited: S,
@@ -52,7 +52,7 @@ pub struct OnTransition<S: States> {
 ///
 /// [`PreStartup`]: https://docs.rs/bevy/latest/bevy/prelude/struct.PreStartup.html
 /// [`PreUpdate`]: https://docs.rs/bevy/latest/bevy/prelude/struct.PreUpdate.html
-#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
 pub struct StateTransition;
 
 /// Event sent when any state transition of `S` happens.