Merge AppBuilder into App (bevyengine#2531)

This is extracted out of eb8f973 and includes some additional changes to remove all references to AppBuilder and fix examples that still used App::build() instead of App::new(). In addition I didn't extract the sub app feature as it isn't ready yet.

You can use `git diff --diff-filter=M eb8f973` to find all differences in this PR. The `--diff-filtered=M` filters all files added in the original commit but not in this commit away.

Co-Authored-By: Carter Anderson <mcanders1@gmail.com>

Author: bjorn3

crates/bevy_app/src/app.rs

@@ -1,6 +1,6 @@
 use serde::Deserialize;
 
-use crate::{app::AppExit, AppBuilder};
+use crate::{app::AppExit, App};
 use bevy_ecs::system::IntoSystem;
 
 /// Configuration for automated testing on CI
@@ -23,7 +23,7 @@ fn ci_testing_exit_after(
     *current_frame += 1;
 }
 
-pub(crate) fn setup_app(app_builder: &mut AppBuilder) -> &mut AppBuilder {
+pub(crate) fn setup_app(app_builder: &mut App) -> &mut App {
     let filename =
         std::env::var("CI_TESTING_CONFIG").unwrap_or_else(|_| "ci_testing_config.ron".to_string());
     let config: CiTestingConfig = ron::from_str(

crates/bevy_app/src/app_builder.rs

@@ -1,5 +1,4 @@
 mod app;
-mod app_builder;
 mod plugin;
 mod plugin_group;
 mod schedule_runner;
@@ -8,7 +7,6 @@ mod schedule_runner;
 mod ci_testing;
 
 pub use app::*;
-pub use app_builder::*;
 pub use bevy_derive::DynamicPlugin;
 pub use bevy_ecs::event::*;
 pub use plugin::*;
@@ -17,10 +15,7 @@ pub use schedule_runner::*;
 
 pub mod prelude {
     #[doc(hidden)]
-    pub use crate::{
-        app::App, app_builder::AppBuilder, CoreStage, DynamicPlugin, Plugin, PluginGroup,
-        StartupStage,
-    };
+    pub use crate::{app::App, CoreStage, DynamicPlugin, Plugin, PluginGroup, StartupStage};
 }
 
 use bevy_ecs::schedule::StageLabel;

crates/bevy_app/src/ci_testing.rs

@@ -1,12 +1,12 @@
-use crate::AppBuilder;
+use crate::App;
 use std::any::Any;
 
 /// A collection of Bevy App logic and configuration
 ///
-/// Plugins use [AppBuilder] to configure an [App](crate::App). When an [App](crate::App) registers
+/// Plugins configure an [App](crate::App). When an [App](crate::App) registers
 /// a plugin, the plugin's [Plugin::build] function is run.
 pub trait Plugin: Any + Send + Sync {
-    fn build(&self, app: &mut AppBuilder);
+    fn build(&self, app: &mut App);
     fn name(&self) -> &str {
         std::any::type_name::<Self>()
     }

crates/bevy_app/src/lib.rs

@@ -1,4 +1,4 @@
-use crate::{AppBuilder, Plugin};
+use crate::{App, Plugin};
 use bevy_utils::{tracing::debug, HashMap};
 use std::any::TypeId;
 
@@ -96,7 +96,7 @@ impl PluginGroupBuilder {
         self
     }
 
-    pub fn finish(self, app: &mut AppBuilder) {
+    pub fn finish(self, app: &mut App) {
         for ty in self.order.iter() {
             if let Some(entry) = self.plugins.get(ty) {
                 if entry.enabled {

crates/bevy_app/src/plugin.rs

@@ -1,5 +1,8 @@
-use super::{App, AppBuilder};
-use crate::{app::AppExit, plugin::Plugin, ManualEventReader};
+use crate::{
+    app::{App, AppExit},
+    plugin::Plugin,
+    ManualEventReader,
+};
 use bevy_ecs::event::Events;
 use bevy_utils::{Duration, Instant};
 
@@ -48,9 +51,9 @@ impl ScheduleRunnerSettings {
 pub struct ScheduleRunnerPlugin {}
 
 impl Plugin for ScheduleRunnerPlugin {
-    fn build(&self, app: &mut AppBuilder) {
+    fn build(&self, app: &mut App) {
         let settings = app
-            .world_mut()
+            .world
             .get_resource_or_insert_with(ScheduleRunnerSettings::default)
             .to_owned();
         app.set_runner(move |mut app: App| {

crates/bevy_app/src/plugin_group.rs

@@ -2,7 +2,7 @@ use crate::{
     update_asset_storage_system, Asset, AssetLoader, AssetServer, AssetStage, Handle, HandleId,
     RefChange,
 };
-use bevy_app::{AppBuilder, EventWriter, Events};
+use bevy_app::{App, EventWriter, Events};
 use bevy_ecs::{
     system::{IntoSystem, ResMut},
     world::FromWorld,
@@ -193,7 +193,7 @@ impl<T: Asset> Assets<T> {
     }
 }
 
-/// [AppBuilder] extension methods for adding new asset types
+/// [App] extension methods for adding new asset types
 pub trait AddAsset {
     fn add_asset<T>(&mut self) -> &mut Self
     where
@@ -206,13 +206,13 @@ pub trait AddAsset {
         T: AssetLoader;
 }
 
-impl AddAsset for AppBuilder {
+impl AddAsset for App {
     fn add_asset<T>(&mut self) -> &mut Self
     where
         T: Asset,
     {
         let assets = {
-            let asset_server = self.world().get_resource::<AssetServer>().unwrap();
+            let asset_server = self.world.get_resource::<AssetServer>().unwrap();
             asset_server.register_asset_type::<T>()
         };
 
@@ -233,15 +233,15 @@ impl AddAsset for AppBuilder {
     where
         T: AssetLoader + FromWorld,
     {
-        let result = T::from_world(self.world_mut());
+        let result = T::from_world(&mut self.world);
         self.add_asset_loader(result)
     }
 
     fn add_asset_loader<T>(&mut self, loader: T) -> &mut Self
     where
         T: AssetLoader,
     {
-        self.world_mut()
+        self.world
             .get_resource_mut::<AssetServer>()
             .expect("AssetServer does not exist. Consider adding it as a resource.")
             .add_loader(loader);

crates/bevy_app/src/schedule_runner.rs

@@ -17,7 +17,7 @@ impl<T: Asset> Default for AssetCountDiagnosticsPlugin<T> {
 }
 
 impl<T: Asset> Plugin for AssetCountDiagnosticsPlugin<T> {
-    fn build(&self, app: &mut AppBuilder) {
+    fn build(&self, app: &mut App) {
         app.add_startup_system(Self::setup_system.system())
             .add_system(Self::diagnostic_system.system());
     }

crates/bevy_asset/src/assets.rs

@@ -26,7 +26,7 @@ pub use io::*;
 pub use loader::*;
 pub use path::*;
 
-use bevy_app::{prelude::Plugin, AppBuilder};
+use bevy_app::{prelude::Plugin, App};
 use bevy_ecs::{
     schedule::{StageLabel, SystemStage},
     system::IntoSystem,
@@ -61,9 +61,9 @@ impl Default for AssetServerSettings {
 ///
 /// This is useful when providing a custom `AssetIo` instance that needs to
 /// delegate to the default `AssetIo` for the platform.
-pub fn create_platform_default_asset_io(app: &mut AppBuilder) -> Box<dyn AssetIo> {
+pub fn create_platform_default_asset_io(app: &mut App) -> Box<dyn AssetIo> {
     let settings = app
-        .world_mut()
+        .world
         .get_resource_or_insert_with(AssetServerSettings::default);
 
     #[cfg(all(not(target_arch = "wasm32"), not(target_os = "android")))]
@@ -77,10 +77,10 @@ pub fn create_platform_default_asset_io(app: &mut AppBuilder) -> Box<dyn AssetIo
 }
 
 impl Plugin for AssetPlugin {
-    fn build(&self, app: &mut AppBuilder) {
-        if app.world().get_resource::<AssetServer>().is_none() {
+    fn build(&self, app: &mut App) {
+        if app.world.get_resource::<AssetServer>().is_none() {
             let task_pool = app
-                .world()
+                .world
                 .get_resource::<IoTaskPool>()
                 .expect("`IoTaskPool` resource not found.")
                 .0