Add upstream bevy_ecs and prepare for custom-shaders merge (#2815)

This updates the `pipelined-rendering` branch to use the latest `bevy_ecs` from `main`. This accomplishes a couple of goals:

1. prepares for upcoming `custom-shaders` branch changes, which were what drove many of the recent bevy_ecs changes on `main`
2. prepares for the soon-to-happen merge of `pipelined-rendering` into `main`. By including bevy_ecs changes now, we make that merge simpler / easier to review. 

I split this up into 3 commits:

1. **add upstream bevy_ecs**: please don't bother reviewing this content. it has already received thorough review on `main` and is a literal copy/paste of the relevant folders (the old folders were deleted so the directories are literally exactly the same as `main`).
2. **support manual buffer application in stages**: this is used to enable the Extract step. we've already reviewed this once on the `pipelined-rendering` branch, but its worth looking at one more time in the new context of (1).
3. **support manual archetype updates in QueryState**: same situation as (2).

Cargo.toml

@@ -365,10 +365,6 @@ path = "examples/ecs/system_sets.rs"
 name = "timers"
 path = "examples/ecs/timers.rs"
 
-[[example]]
-name = "query_bundle"
-path = "examples/ecs/query_bundle.rs"
-
 # Games
 [[example]]
 name = "alien_cake_addict"

crates/bevy_ecs/Cargo.toml

@@ -2,10 +2,6 @@
 name = "bevy_ecs"
 version = "0.5.0"
 edition = "2018"
-authors = [
-    "Bevy Contributors <bevyengine@gmail.com>",
-    "Carter Anderson <mcanders1@gmail.com>",
-]
 description = "Bevy Engine's entity component system"
 homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"

crates/bevy_ecs/README.md

@@ -131,7 +131,7 @@ fn main() {
     // Add a Stage to our schedule. Each Stage in a schedule runs all of its systems
     // before moving on to the next Stage
     schedule.add_stage("update", SystemStage::parallel()
-        .with_system(movement.system())
+        .with_system(movement)
     );
 
     // Run the schedule once. If your app has a "loop", you would run this once per loop

crates/bevy_ecs/examples/change_detection.rs

@@ -24,15 +24,11 @@ fn main() {
 
     // Add systems to the Stage to execute our app logic
     // We can label our systems to force a specific run-order between some of them
-    update.add_system(spawn_entities.system().label(SimulationSystem::Spawn));
+    update.add_system(spawn_entities.label(SimulationSystem::Spawn));
-    update.add_system(
+    update.add_system(print_counter_when_changed.after(SimulationSystem::Spawn));
-        print_counter_when_changed
+    update.add_system(age_all_entities.label(SimulationSystem::Age));
-            .system()
+    update.add_system(remove_old_entities.after(SimulationSystem::Age));
-            .after(SimulationSystem::Spawn),
+    update.add_system(print_changed_entities.after(SimulationSystem::Age));
-    );
-    update.add_system(age_all_entities.system().label(SimulationSystem::Age));
-    update.add_system(remove_old_entities.system().after(SimulationSystem::Age));
-    update.add_system(print_changed_entities.system().after(SimulationSystem::Age));
     // Add the Stage with our systems to the Schedule
     schedule.add_stage("update", update);
 

crates/bevy_ecs/examples/component_storage.rs

@@ -22,7 +22,7 @@ fn main() {
     // Setup a schedule and stage to add a system querying for the just spawned entities
     let mut schedule = Schedule::default();
     let mut update = SystemStage::parallel();
-    update.add_system(query_entities.system());
+    update.add_system(query_entities);
     schedule.add_stage("update", update);
 
     schedule.run(&mut world);

crates/bevy_ecs/examples/events.rs

@@ -16,13 +16,13 @@ fn main() {
     // called "second". In "first" we update the events and in "second" we run our systems
     // sending and receiving events.
     let mut first = SystemStage::parallel();
-    first.add_system(Events::<MyEvent>::update_system.system());
+    first.add_system(Events::<MyEvent>::update_system);
     schedule.add_stage("first", first);
 
     // Add systems sending and receiving events to a "second" Stage
     let mut second = SystemStage::parallel();
-    second.add_system(sending_system.system().label(EventSystem::Sending));
+    second.add_system(sending_system.label(EventSystem::Sending));
-    second.add_system(receiving_system.system().after(EventSystem::Sending));
+    second.add_system(receiving_system.after(EventSystem::Sending));
 
     // Run the "second" Stage after the "first" Stage, so our Events always get updated before we use them
     schedule.add_stage_after("first", "second", second);
@@ -41,7 +41,6 @@ enum EventSystem {
 }
 
 // This is our event that we will send and receive in systems
-#[derive(Debug)]
 struct MyEvent {
     pub message: String,
     pub random_value: f32,
@@ -62,6 +61,9 @@ fn sending_system(mut event_writer: EventWriter<MyEvent>) {
 // If an event is received it will be printed to the console
 fn receiving_system(mut event_reader: EventReader<MyEvent>) {
     for my_event in event_reader.iter() {
-        println!("    Received: {:?}", *my_event);
+        println!(
+            "    Received message {:?}, with random value of {}",
+            my_event.message, my_event.random_value
+        );
     }
 }

crates/bevy_ecs/examples/resources.rs

@@ -16,8 +16,8 @@ fn main() {
     let mut update = SystemStage::parallel();
 
     // Add systems to increase the counter and to print out the current value
-    update.add_system(increase_counter.system().label(CounterSystem::Increase));
+    update.add_system(increase_counter.label(CounterSystem::Increase));
-    update.add_system(print_counter.system().after(CounterSystem::Increase));
+    update.add_system(print_counter.after(CounterSystem::Increase));
     schedule.add_stage("update", update);
 
     for iteration in 1..=10 {

crates/bevy_ecs/macros/src/lib.rs

@@ -1,16 +1,16 @@
 extern crate proc_macro;
 
-use bevy_macro_utils::{derive_label, BevyManifest};
+use bevy_macro_utils::BevyManifest;
 use proc_macro::TokenStream;
-use proc_macro2::Span;
+use proc_macro2::{Span, TokenStream as TokenStream2};
 use quote::{format_ident, quote};
 use syn::{
     parse::{Parse, ParseStream},
     parse_macro_input,
     punctuated::Punctuated,
     token::Comma,
-    Data, DataStruct, DeriveInput, Field, Fields, GenericParam, Ident, Index, Lifetime, LitInt,
+    Data, DataStruct, DeriveInput, Field, Fields, GenericParam, Ident, Index, LitInt, Path, Result,
-    Result, Token,
+    Token,
 };
 
 struct AllTuples {
@@ -110,15 +110,15 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
         .map(|field| &field.ty)
         .collect::<Vec<_>>();
 
-    let mut field_type_infos = Vec::new();
+    let mut field_component_ids = Vec::new();
     let mut field_get_components = Vec::new();
     let mut field_from_components = Vec::new();
     for ((field_type, is_bundle), field) in
         field_type.iter().zip(is_bundle.iter()).zip(field.iter())
     {
         if *is_bundle {
-            field_type_infos.push(quote! {
+            field_component_ids.push(quote! {
-                type_info.extend(<#field_type as #ecs_path::bundle::Bundle>::type_info());
+                component_ids.extend(<#field_type as #ecs_path::bundle::Bundle>::component_ids(components));
             });
             field_get_components.push(quote! {
                 self.#field.get_components(&mut func);
@@ -127,8 +127,8 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
                 #field: <#field_type as #ecs_path::bundle::Bundle>::from_components(&mut func),
             });
         } else {
-            field_type_infos.push(quote! {
+            field_component_ids.push(quote! {
-                type_info.push(#ecs_path::component::TypeInfo::of::<#field_type>());
+                component_ids.push(components.get_or_insert_id::<#field_type>());
             });
             field_get_components.push(quote! {
                 func((&mut self.#field as *mut #field_type).cast::<u8>());
@@ -147,10 +147,12 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
     TokenStream::from(quote! {
         /// SAFE: TypeInfo is returned in field-definition-order. [from_components] and [get_components] use field-definition-order
         unsafe impl #impl_generics #ecs_path::bundle::Bundle for #struct_name#ty_generics #where_clause {
-            fn type_info() -> Vec<#ecs_path::component::TypeInfo> {
+            fn component_ids(
-                let mut type_info = Vec::with_capacity(#field_len);
+                components: &mut #ecs_path::component::Components,
-                #(#field_type_infos)*
+            ) -> Vec<#ecs_path::component::ComponentId> {
-                type_info
+                let mut component_ids = Vec::with_capacity(#field_len);
+                #(#field_component_ids)*
+                component_ids
             }
 
             #[allow(unused_variables, unused_mut, non_snake_case)]
@@ -174,38 +176,26 @@ fn get_idents(fmt_string: fn(usize) -> String, count: usize) -> Vec<Ident> {
         .collect::<Vec<Ident>>()
 }
 
-fn get_lifetimes(fmt_string: fn(usize) -> String, count: usize) -> Vec<Lifetime> {
-    (0..count)
-        .map(|i| Lifetime::new(&fmt_string(i), Span::call_site()))
-        .collect::<Vec<Lifetime>>()
-}
-
 #[proc_macro]
 pub fn impl_query_set(_input: TokenStream) -> TokenStream {
     let mut tokens = TokenStream::new();
     let max_queries = 4;
     let queries = get_idents(|i| format!("Q{}", i), max_queries);
     let filters = get_idents(|i| format!("F{}", i), max_queries);
-    let lifetimes = get_lifetimes(|i| format!("'q{}", i), max_queries);
-    let state_lifetimes = get_lifetimes(|i| format!("'qs{}", i), max_queries);
-    let mut query_fns = Vec::new();
     let mut query_fn_muts = Vec::new();
     for i in 0..max_queries {
         let query = &queries[i];
         let filter = &filters[i];
-        let lifetime = &lifetimes[i];
-        let state_lifetime = &state_lifetimes[i];
         let fn_name = Ident::new(&format!("q{}", i), Span::call_site());
-        let fn_name_mut = Ident::new(&format!("q{}_mut", i), Span::call_site());
         let index = Index::from(i);
-        query_fns.push(quote! {
-            pub fn #fn_name(&self) -> &Query<#lifetime, #state_lifetime, #query, #filter> {
-                &self.0.#index
-            }
-        });
         query_fn_muts.push(quote! {
-            pub fn #fn_name_mut(&mut self) -> &mut Query<#lifetime, #state_lifetime, #query, #filter> {
+            pub fn #fn_name(&mut self) -> Query<'_, '_, #query, #filter> {
-                &mut self.0.#index
+                // SAFE: systems run without conflicts with other systems.
+                // Conflicting queries in QuerySet are not accessible at the same time
+                // QuerySets are guaranteed to not conflict with other SystemParams
+                unsafe {
+                    Query::new(self.world, &self.query_states.#index, self.last_change_tick, self.change_tick)
+                }
             }
         });
     }
@@ -213,12 +203,9 @@ pub fn impl_query_set(_input: TokenStream) -> TokenStream {
     for query_count in 1..=max_queries {
         let query = &queries[0..query_count];
         let filter = &filters[0..query_count];
-        let lifetime = &lifetimes[0..query_count];
-        let state_lifetime = &state_lifetimes[0..query_count];
-        let query_fn = &query_fns[0..query_count];
         let query_fn_mut = &query_fn_muts[0..query_count];
         tokens.extend(TokenStream::from(quote! {
-            impl<'s, #(#lifetime,)* #(#query: WorldQuery + 'static,)* #(#filter: WorldQuery + 'static,)*> SystemParam for QuerySet<(#(Query<#lifetime, 's, #query, #filter>,)*)>
+            impl<'w, 's, #(#query: WorldQuery + 'static,)* #(#filter: WorldQuery + 'static,)*> SystemParam for QuerySet<'w, 's, (#(QueryState<#query, #filter>,)*)>
                 where #(#filter::Fetch: FilterFetch,)*
             {
                 type Fetch = QuerySetState<(#(QueryState<#query, #filter>,)*)>;
@@ -271,10 +258,10 @@ pub fn impl_query_set(_input: TokenStream) -> TokenStream {
                 fn default_config() {}
             }
 
-            impl<'s, 'w, #(#query: WorldQuery + 'static,)* #(#filter: WorldQuery + 'static,)*> SystemParamFetch<'s, 'w> for QuerySetState<(#(QueryState<#query, #filter>,)*)>
+            impl<'w, 's, #(#query: WorldQuery + 'static,)* #(#filter: WorldQuery + 'static,)*> SystemParamFetch<'w, 's> for QuerySetState<(#(QueryState<#query, #filter>,)*)>
                 where #(#filter::Fetch: FilterFetch,)*
             {
-                type Item = QuerySet<(#(Query<'w, 's, #query, #filter>,)*)>;
+                type Item = QuerySet<'w, 's, (#(QueryState<#query, #filter>,)*)>;
 
                 #[inline]
                 unsafe fn get_param(
@@ -283,15 +270,18 @@ pub fn impl_query_set(_input: TokenStream) -> TokenStream {
                     world: &'w World,
                     change_tick: u32,
                 ) -> Self::Item {
-                    let (#(#query,)*) = &state.0;
+                    QuerySet {
-                    QuerySet((#(Query::new(world, #query, system_meta.last_change_tick, change_tick),)*))
+                        query_states: &state.0,
+                        world,
+                        last_change_tick: system_meta.last_change_tick,
+                        change_tick,
+                    }
                 }
             }
 
-            impl<#(#state_lifetime,)* #(#lifetime,)* #(#query: WorldQuery,)* #(#filter: WorldQuery,)*> QuerySet<(#(Query<#lifetime, #state_lifetime, #query, #filter>,)*)>
+            impl<'w, 's, #(#query: WorldQuery,)* #(#filter: WorldQuery,)*> QuerySet<'w, 's, (#(QueryState<#query, #filter>,)*)>
                 where #(#filter::Fetch: FilterFetch,)*
             {
-                #(#query_fn)*
                 #(#query_fn_mut)*
             }
         }));
@@ -385,7 +375,7 @@ pub fn derive_system_param(input: TokenStream) -> TokenStream {
 
     TokenStream::from(quote! {
         impl #impl_generics #path::system::SystemParam for #struct_name#ty_generics #where_clause {
-            type Fetch = #fetch_struct_name <(#(<#field_types as SystemParam>::Fetch,)*), #punctuated_generic_idents>;
+            type Fetch = #fetch_struct_name <(#(<#field_types as #path::system::SystemParam>::Fetch,)*), #punctuated_generic_idents>;
         }
 
         #[doc(hidden)]
@@ -416,7 +406,7 @@ pub fn derive_system_param(input: TokenStream) -> TokenStream {
             }
         }
 
-        impl #impl_generics #path::system::SystemParamFetch<'s, 'w> for #fetch_struct_name <(#(<#field_types as SystemParam>::Fetch,)*), #punctuated_generic_idents> {
+        impl #impl_generics #path::system::SystemParamFetch<'w, 's> for #fetch_struct_name <(#(<#field_types as #path::system::SystemParam>::Fetch,)*), #punctuated_generic_idents> {
             type Item = #struct_name#ty_generics;
             unsafe fn get_param(
                 state: &'s mut Self,
@@ -425,7 +415,7 @@ pub fn derive_system_param(input: TokenStream) -> TokenStream {
                 change_tick: u32,
             ) -> Self::Item {
                 #struct_name {
-                    #(#fields: <<#field_types as SystemParam>::Fetch as #path::system::SystemParamFetch>::get_param(&mut state.state.#field_indices, system_meta, world, change_tick),)*
+                    #(#fields: <<#field_types as #path::system::SystemParam>::Fetch as #path::system::SystemParamFetch>::get_param(&mut state.state.#field_indices, system_meta, world, change_tick),)*
                     #(#ignored_fields: <#ignored_field_types>::default(),)*
                 }
             }
@@ -436,43 +426,46 @@ pub fn derive_system_param(input: TokenStream) -> TokenStream {
 #[proc_macro_derive(SystemLabel)]
 pub fn derive_system_label(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-    let mut trait_path = bevy_ecs_path();
+
-    trait_path.segments.push(format_ident!("schedule").into());
+    derive_label(input, Ident::new("SystemLabel", Span::call_site())).into()
-    trait_path
-        .segments
-        .push(format_ident!("SystemLabel").into());
-    derive_label(input, trait_path)
 }
 
 #[proc_macro_derive(StageLabel)]
 pub fn derive_stage_label(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-    let mut trait_path = bevy_ecs_path();
+    derive_label(input, Ident::new("StageLabel", Span::call_site())).into()
-    trait_path.segments.push(format_ident!("schedule").into());
-    trait_path.segments.push(format_ident!("StageLabel").into());
-    derive_label(input, trait_path)
 }
 
 #[proc_macro_derive(AmbiguitySetLabel)]
 pub fn derive_ambiguity_set_label(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-    let mut trait_path = bevy_ecs_path();
+    derive_label(input, Ident::new("AmbiguitySetLabel", Span::call_site())).into()
-    trait_path.segments.push(format_ident!("schedule").into());
-    trait_path
-        .segments
-        .push(format_ident!("AmbiguitySetLabel").into());
-    derive_label(input, trait_path)
 }
 
 #[proc_macro_derive(RunCriteriaLabel)]
 pub fn derive_run_criteria_label(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-    let mut trait_path = bevy_ecs_path();
+    derive_label(input, Ident::new("RunCriteriaLabel", Span::call_site())).into()
-    trait_path.segments.push(format_ident!("schedule").into());
+}
-    trait_path
+
-        .segments
+fn derive_label(input: DeriveInput, label_type: Ident) -> TokenStream2 {
-        .push(format_ident!("RunCriteriaLabel").into());
+    let ident = input.ident;
-    derive_label(input, trait_path)
+    let ecs_path: Path = bevy_ecs_path();
+
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+    let mut where_clause = where_clause.cloned().unwrap_or_else(|| syn::WhereClause {
+        where_token: Default::default(),
+        predicates: Default::default(),
+    });
+    where_clause.predicates.push(syn::parse2(quote! { Self: Eq + ::std::fmt::Debug + ::std::hash::Hash + Clone + Send + Sync + 'static }).unwrap());
+
+    quote! {
+        impl #impl_generics #ecs_path::schedule::#label_type for #ident #ty_generics #where_clause {
+            fn dyn_clone(&self) -> Box<dyn #ecs_path::schedule::#label_type> {
+                Box::new(Clone::clone(self))
+            }
+        }
+    }
 }
 
 fn bevy_ecs_path() -> syn::Path {

crates/bevy_ecs/src/archetype.rs

@@ -15,26 +15,15 @@ use std::{
 pub struct ArchetypeId(usize);
 
 impl ArchetypeId {
+    pub const EMPTY: ArchetypeId = ArchetypeId(0);
+    pub const RESOURCE: ArchetypeId = ArchetypeId(1);
+    pub const INVALID: ArchetypeId = ArchetypeId(usize::MAX);
+
     #[inline]
     pub const fn new(index: usize) -> Self {
         ArchetypeId(index)
     }
 
-    #[inline]
-    pub const fn empty() -> ArchetypeId {
-        ArchetypeId(0)
-    }
-
-    #[inline]
-    pub const fn invalid() -> ArchetypeId {
-        ArchetypeId(usize::MAX)
-    }
-
-    #[inline]
-    pub const fn resource() -> ArchetypeId {
-        ArchetypeId(1)
-    }
-
     #[inline]
     pub fn index(self) -> usize {
         self.0
@@ -65,7 +54,7 @@ impl Edges {
     }
 
     #[inline]
-    pub fn set_add_bundle(
+    pub fn insert_add_bundle(
         &mut self,
         bundle_id: BundleId,
         archetype_id: ArchetypeId,
@@ -86,7 +75,7 @@ impl Edges {
     }
 
     #[inline]
-    pub fn set_remove_bundle(&mut self, bundle_id: BundleId, archetype_id: Option<ArchetypeId>) {
+    pub fn insert_remove_bundle(&mut self, bundle_id: BundleId, archetype_id: Option<ArchetypeId>) {
         self.remove_bundle.insert(bundle_id, archetype_id);
     }
 
@@ -99,7 +88,7 @@ impl Edges {
     }
 
     #[inline]
-    pub fn set_remove_bundle_intersection(
+    pub fn insert_remove_bundle_intersection(
         &mut self,
         bundle_id: BundleId,
         archetype_id: Option<ArchetypeId>,
@@ -115,8 +104,8 @@ struct TableInfo {
 }
 
 pub(crate) struct ArchetypeSwapRemoveResult {
-    pub swapped_entity: Option<Entity>,
+    pub(crate) swapped_entity: Option<Entity>,
-    pub table_row: usize,
+    pub(crate) table_row: usize,
 }
 
 pub(crate) struct ArchetypeComponentInfo {
@@ -387,7 +376,7 @@ impl Default for Archetypes {
         // adds the resource archetype. it is "special" in that it is inaccessible via a "hash",
         // which prevents entities from being added to it
         archetypes.archetypes.push(Archetype::new(
-            ArchetypeId::resource(),
+            ArchetypeId::RESOURCE,
             TableId::empty(),
             Cow::Owned(Vec::new()),
             Cow::Owned(Vec::new()),
@@ -412,7 +401,7 @@ impl Archetypes {
     #[inline]
     pub fn empty(&self) -> &Archetype {
         // SAFE: empty archetype always exists
-        unsafe { self.archetypes.get_unchecked(ArchetypeId::empty().index()) }
+        unsafe { self.archetypes.get_unchecked(ArchetypeId::EMPTY.index()) }
     }
 
     #[inline]
@@ -420,17 +409,14 @@ impl Archetypes {
         // SAFE: empty archetype always exists
         unsafe {
             self.archetypes
-                .get_unchecked_mut(ArchetypeId::empty().index())
+                .get_unchecked_mut(ArchetypeId::EMPTY.index())
         }
     }
 
     #[inline]
     pub fn resource(&self) -> &Archetype {
         // SAFE: resource archetype always exists
-        unsafe {
+        unsafe { self.archetypes.get_unchecked(ArchetypeId::RESOURCE.index()) }
-            self.archetypes
-                .get_unchecked(ArchetypeId::resource().index())
-        }
     }
 
     #[inline]
@@ -438,7 +424,7 @@ impl Archetypes {
         // SAFE: resource archetype always exists
         unsafe {
             self.archetypes
-                .get_unchecked_mut(ArchetypeId::resource().index())
+                .get_unchecked_mut(ArchetypeId::RESOURCE.index())
         }
     }
 

crates/bevy_ecs/src/bundle.rs

@@ -1,10 +1,10 @@
 pub use bevy_ecs_macros::Bundle;
 
 use crate::{
-    archetype::ComponentStatus,
+    archetype::{AddBundle, Archetype, ArchetypeId, Archetypes, ComponentStatus},
-    component::{Component, ComponentId, ComponentTicks, Components, StorageType, TypeInfo},
+    component::{Component, ComponentId, ComponentTicks, Components, StorageType},
-    entity::Entity,
+    entity::{Entities, Entity, EntityLocation},
-    storage::{SparseSetIndex, SparseSets, Table},
+    storage::{SparseSetIndex, SparseSets, Storages, Table},
 };
 use bevy_ecs_macros::all_tuples;
 use std::{any::TypeId, collections::HashMap};
@@ -12,8 +12,6 @@ use std::{any::TypeId, collections::HashMap};
 /// An ordered collection of components, commonly used for spawning entities, and adding and
 /// removing components in bulk.
 ///
-/// In order to query for components in a bundle use [crate::query::WithBundle].
-///
 /// Typically, you will simply use `#[derive(Bundle)]` when creating your own `Bundle`.
 /// The `Bundle` trait is automatically implemented for tuples of components:
 /// `(ComponentA, ComponentB)` is a very convenient shorthand when working with one-off collections
@@ -38,13 +36,13 @@ use std::{any::TypeId, collections::HashMap};
 /// ```
 ///
 /// # Safety
-/// [Bundle::type_info] must return the TypeInfo for each component type in the bundle, in the
+/// [Bundle::component_id] must return the ComponentId for each component type in the bundle, in the
 /// _exact_ order that [Bundle::get_components] is called.
-/// [Bundle::from_components] must call `func` exactly once for each [TypeInfo] returned by
+/// [Bundle::from_components] must call `func` exactly once for each [ComponentId] returned by
-/// [Bundle::type_info]
+/// [Bundle::component_id]
 pub unsafe trait Bundle: Send + Sync + 'static {
-    /// Gets this [Bundle]'s components type info, in the order of this bundle's Components
+    /// Gets this [Bundle]'s component ids, in the order of this bundle's Components
-    fn type_info() -> Vec<TypeInfo>;
+    fn component_ids(components: &mut Components) -> Vec<ComponentId>;
 
     /// Calls `func`, which should return data for each component in the bundle, in the order of
     /// this bundle's Components
@@ -66,8 +64,9 @@ macro_rules! tuple_impl {
     ($($name: ident),*) => {
         /// SAFE: TypeInfo is returned in tuple-order. [Bundle::from_components] and [Bundle::get_components] use tuple-order
         unsafe impl<$($name: Component),*> Bundle for ($($name,)*) {
-            fn type_info() -> Vec<TypeInfo> {
+            #[allow(unused_variables)]
-                vec![$(TypeInfo::of::<$name>()),*]
+            fn component_ids(components: &mut Components) -> Vec<ComponentId> {
+                vec![$(components.get_or_insert_id::<$name>()),*]
             }
 
             #[allow(unused_variables, unused_mut)]
@@ -123,19 +122,119 @@ pub struct BundleInfo {
 }
 
 impl BundleInfo {
-    /// # Safety
-    /// table row must exist, entity must be valid
-    #[allow(clippy::too_many_arguments)]
     #[inline]
-    pub(crate) unsafe fn write_components<T: Bundle>(
+    pub fn id(&self) -> BundleId {
-        &self,
+        self.id
-        sparse_sets: &mut SparseSets,
+    }
-        entity: Entity,
+
-        table: &mut Table,
+    #[inline]
-        table_row: usize,
+    pub fn components(&self) -> &[ComponentId] {
-        bundle_status: &[ComponentStatus],
+        &self.component_ids
-        bundle: T,
+    }
+
+    #[inline]
+    pub fn storage_types(&self) -> &[StorageType] {
+        &self.storage_types
+    }
+
+    pub(crate) fn get_bundle_inserter<'a, 'b>(
+        &'b self,
+        entities: &'a mut Entities,
+        archetypes: &'a mut Archetypes,
+        components: &mut Components,
+        storages: &'a mut Storages,
+        archetype_id: ArchetypeId,
         change_tick: u32,
+    ) -> BundleInserter<'a, 'b> {
+        let new_archetype_id =
+            self.add_bundle_to_archetype(archetypes, storages, components, archetype_id);
+        let archetypes_ptr = archetypes.archetypes.as_mut_ptr();
+        if new_archetype_id == archetype_id {
+            let archetype = &mut archetypes[archetype_id];
+            let table_id = archetype.table_id();
+            BundleInserter {
+                bundle_info: self,
+                archetype,
+                entities,
+                sparse_sets: &mut storages.sparse_sets,
+                table: &mut storages.tables[table_id],
+                archetypes_ptr,
+                change_tick,
+                result: InsertBundleResult::SameArchetype,
+            }
+        } else {
+            let (archetype, new_archetype) = archetypes.get_2_mut(archetype_id, new_archetype_id);
+            let table_id = archetype.table_id();
+            if table_id == new_archetype.table_id() {
+                BundleInserter {
+                    bundle_info: self,
+                    archetype,
+                    archetypes_ptr,
+                    entities,
+                    sparse_sets: &mut storages.sparse_sets,
+                    table: &mut storages.tables[table_id],
+                    change_tick,
+                    result: InsertBundleResult::NewArchetypeSameTable { new_archetype },
+                }
+            } else {
+                let (table, new_table) = storages
+                    .tables
+                    .get_2_mut(table_id, new_archetype.table_id());
+                BundleInserter {
+                    bundle_info: self,
+                    archetype,
+                    sparse_sets: &mut storages.sparse_sets,
+                    entities,
+                    archetypes_ptr,
+                    table,
+                    change_tick,
+                    result: InsertBundleResult::NewArchetypeNewTable {
+                        new_archetype,
+                        new_table,
+                    },
+                }
+            }
+        }
+    }
+
+    pub(crate) fn get_bundle_spawner<'a, 'b>(
+        &'b self,
+        entities: &'a mut Entities,
+        archetypes: &'a mut Archetypes,
+        components: &mut Components,
+        storages: &'a mut Storages,
+        change_tick: u32,
+    ) -> BundleSpawner<'a, 'b> {
+        let new_archetype_id =
+            self.add_bundle_to_archetype(archetypes, storages, components, ArchetypeId::EMPTY);
+        let (empty_archetype, archetype) =
+            archetypes.get_2_mut(ArchetypeId::EMPTY, new_archetype_id);
+        let table = &mut storages.tables[archetype.table_id()];
+        let add_bundle = empty_archetype.edges().get_add_bundle(self.id()).unwrap();
+        BundleSpawner {
+            archetype,
+            add_bundle,
+            bundle_info: self,
+            table,
+            entities,
+            sparse_sets: &mut storages.sparse_sets,
+            change_tick,
+        }
+    }
+
+    /// # Safety
+    /// `table` must be the "new" table for `entity`. `table_row` must have space allocated for the `entity`, `bundle` must match this BundleInfo's type
+    #[inline]
+    #[allow(clippy::too_many_arguments)]
+    unsafe fn write_components<T: Bundle>(
+        &self,
+        table: &mut Table,
+        sparse_sets: &mut SparseSets,
+        add_bundle: &AddBundle,
+        entity: Entity,
+        table_row: usize,
+        change_tick: u32,
+        bundle: T,
     ) {
         // NOTE: get_components calls this closure on each component in "bundle order".
         // bundle_info.component_ids are also in "bundle order"
@@ -145,7 +244,7 @@ impl BundleInfo {
             match self.storage_types[bundle_component] {
                 StorageType::Table => {
                     let column = table.get_column_mut(component_id).unwrap();
-                    match bundle_status.get_unchecked(bundle_component) {
+                    match add_bundle.bundle_status.get_unchecked(bundle_component) {
                         ComponentStatus::Added => {
                             column.initialize(
                                 table_row,
@@ -167,19 +266,277 @@ impl BundleInfo {
         });
     }
 
+    /// Adds a bundle to the given archetype and returns the resulting archetype. This could be the same
+    /// [ArchetypeId], in the event that adding the given bundle does not result in an Archetype change.
+    /// Results are cached in the Archetype Graph to avoid redundant work.
+    pub(crate) fn add_bundle_to_archetype(
+        &self,
+        archetypes: &mut Archetypes,
+        storages: &mut Storages,
+        components: &mut Components,
+        archetype_id: ArchetypeId,
+    ) -> ArchetypeId {
+        if let Some(add_bundle) = archetypes[archetype_id].edges().get_add_bundle(self.id) {
+            return add_bundle.archetype_id;
+        }
+        let mut new_table_components = Vec::new();
+        let mut new_sparse_set_components = Vec::new();
+        let mut bundle_status = Vec::with_capacity(self.component_ids.len());
+
+        let current_archetype = &mut archetypes[archetype_id];
+        for component_id in self.component_ids.iter().cloned() {
+            if current_archetype.contains(component_id) {
+                bundle_status.push(ComponentStatus::Mutated);
+            } else {
+                bundle_status.push(ComponentStatus::Added);
+                // SAFE: component_id exists
+                let component_info = unsafe { components.get_info_unchecked(component_id) };
+                match component_info.storage_type() {
+                    StorageType::Table => new_table_components.push(component_id),
+                    StorageType::SparseSet => {
+                        storages.sparse_sets.get_or_insert(component_info);
+                        new_sparse_set_components.push(component_id)
+                    }
+                }
+            }
+        }
+
+        if new_table_components.is_empty() && new_sparse_set_components.is_empty() {
+            let edges = current_archetype.edges_mut();
+            // the archetype does not change when we add this bundle
+            edges.insert_add_bundle(self.id, archetype_id, bundle_status);
+            archetype_id
+        } else {
+            let table_id;
+            let table_components;
+            let sparse_set_components;
+            // the archetype changes when we add this bundle. prepare the new archetype and storages
+            {
+                let current_archetype = &archetypes[archetype_id];
+                table_components = if new_table_components.is_empty() {
+                    // if there are no new table components, we can keep using this table
+                    table_id = current_archetype.table_id();
+                    current_archetype.table_components().to_vec()
+                } else {
+                    new_table_components.extend(current_archetype.table_components());
+                    // sort to ignore order while hashing
+                    new_table_components.sort();
+                    // SAFE: all component ids in `new_table_components` exist
+                    table_id = unsafe {
+                        storages
+                            .tables
+                            .get_id_or_insert(&new_table_components, components)
+                    };
+
+                    new_table_components
+                };
+
+                sparse_set_components = if new_sparse_set_components.is_empty() {
+                    current_archetype.sparse_set_components().to_vec()
+                } else {
+                    new_sparse_set_components.extend(current_archetype.sparse_set_components());
+                    // sort to ignore order while hashing
+                    new_sparse_set_components.sort();
+                    new_sparse_set_components
+                };
+            };
+            let new_archetype_id =
+                archetypes.get_id_or_insert(table_id, table_components, sparse_set_components);
+            // add an edge from the old archetype to the new archetype
+            archetypes[archetype_id].edges_mut().insert_add_bundle(
+                self.id,
+                new_archetype_id,
+                bundle_status,
+            );
+            new_archetype_id
+        }
+    }
+}
+
+pub(crate) struct BundleInserter<'a, 'b> {
+    pub(crate) archetype: &'a mut Archetype,
+    pub(crate) entities: &'a mut Entities,
+    bundle_info: &'b BundleInfo,
+    table: &'a mut Table,
+    sparse_sets: &'a mut SparseSets,
+    result: InsertBundleResult<'a>,
+    archetypes_ptr: *mut Archetype,
+    change_tick: u32,
+}
+
+pub(crate) enum InsertBundleResult<'a> {
+    SameArchetype,
+    NewArchetypeSameTable {
+        new_archetype: &'a mut Archetype,
+    },
+    NewArchetypeNewTable {
+        new_archetype: &'a mut Archetype,
+        new_table: &'a mut Table,
+    },
+}
+
+impl<'a, 'b> BundleInserter<'a, 'b> {
+    /// # Safety
+    /// `entity` must currently exist in the source archetype for this inserter. `archetype_index` must be `entity`'s location in the archetype.
+    /// `T` must match this BundleInfo's type
     #[inline]
-    pub fn id(&self) -> BundleId {
+    pub unsafe fn insert<T: Bundle>(
-        self.id
+        &mut self,
+        entity: Entity,
+        archetype_index: usize,
+        bundle: T,
+    ) -> EntityLocation {
+        let location = EntityLocation {
+            index: archetype_index,
+            archetype_id: self.archetype.id(),
+        };
+        match &mut self.result {
+            InsertBundleResult::SameArchetype => {
+                // PERF: this could be looked up during Inserter construction and stored (but borrowing makes this nasty)
+                let add_bundle = self
+                    .archetype
+                    .edges()
+                    .get_add_bundle(self.bundle_info.id)
+                    .unwrap();
+                self.bundle_info.write_components(
+                    self.table,
+                    self.sparse_sets,
+                    add_bundle,
+                    entity,
+                    self.archetype.entity_table_row(archetype_index),
+                    self.change_tick,
+                    bundle,
+                );
+                location
+            }
+            InsertBundleResult::NewArchetypeSameTable { new_archetype } => {
+                let result = self.archetype.swap_remove(location.index);
+                if let Some(swapped_entity) = result.swapped_entity {
+                    self.entities.meta[swapped_entity.id as usize].location = location;
+                }
+                let new_location = new_archetype.allocate(entity, result.table_row);
+                self.entities.meta[entity.id as usize].location = new_location;
+
+                // PERF: this could be looked up during Inserter construction and stored (but borrowing makes this nasty)
+                let add_bundle = self
+                    .archetype
+                    .edges()
+                    .get_add_bundle(self.bundle_info.id)
+                    .unwrap();
+                self.bundle_info.write_components(
+                    self.table,
+                    self.sparse_sets,
+                    add_bundle,
+                    entity,
+                    result.table_row,
+                    self.change_tick,
+                    bundle,
+                );
+                new_location
+            }
+            InsertBundleResult::NewArchetypeNewTable {
+                new_archetype,
+                new_table,
+            } => {
+                let result = self.archetype.swap_remove(location.index);
+                if let Some(swapped_entity) = result.swapped_entity {
+                    self.entities.meta[swapped_entity.id as usize].location = location;
+                }
+                // PERF: store "non bundle" components in edge, then just move those to avoid
+                // redundant copies
+                let move_result = self
+                    .table
+                    .move_to_superset_unchecked(result.table_row, &mut *new_table);
+                let new_location = new_archetype.allocate(entity, move_result.new_row);
+                self.entities.meta[entity.id as usize].location = new_location;
+
+                // if an entity was moved into this entity's table spot, update its table row
+                if let Some(swapped_entity) = move_result.swapped_entity {
+                    let swapped_location = self.entities.get(swapped_entity).unwrap();
+                    let swapped_archetype = if self.archetype.id() == swapped_location.archetype_id
+                    {
+                        &mut *self.archetype
+                    } else if new_archetype.id() == swapped_location.archetype_id {
+                        &mut *new_archetype
+                    } else {
+                        // SAFE: the only two borrowed archetypes are above and we just did collision checks
+                        &mut *self
+                            .archetypes_ptr
+                            .add(swapped_location.archetype_id.index())
+                    };
+
+                    swapped_archetype
+                        .set_entity_table_row(swapped_location.index, result.table_row);
+                }
+
+                // PERF: this could be looked up during Inserter construction and stored (but borrowing makes this nasty)
+                let add_bundle = self
+                    .archetype
+                    .edges()
+                    .get_add_bundle(self.bundle_info.id)
+                    .unwrap();
+                self.bundle_info.write_components(
+                    new_table,
+                    self.sparse_sets,
+                    add_bundle,
+                    entity,
+                    move_result.new_row,
+                    self.change_tick,
+                    bundle,
+                );
+                new_location
+            }
+        }
+    }
+}
+
+pub(crate) struct BundleSpawner<'a, 'b> {
+    pub(crate) archetype: &'a mut Archetype,
+    pub(crate) entities: &'a mut Entities,
+    add_bundle: &'a AddBundle,
+    bundle_info: &'b BundleInfo,
+    table: &'a mut Table,
+    sparse_sets: &'a mut SparseSets,
+    change_tick: u32,
+}
+
+impl<'a, 'b> BundleSpawner<'a, 'b> {
+    pub fn reserve_storage(&mut self, additional: usize) {
+        self.archetype.reserve(additional);
+        self.table.reserve(additional);
+    }
+    /// # Safety
+    /// `entity` must be allocated (but non existent), `T` must match this BundleInfo's type
+    #[inline]
+    pub unsafe fn spawn_non_existent<T: Bundle>(
+        &mut self,
+        entity: Entity,
+        bundle: T,
+    ) -> EntityLocation {
+        let table_row = self.table.allocate(entity);
+        let location = self.archetype.allocate(entity, table_row);
+        self.bundle_info.write_components(
+            self.table,
+            self.sparse_sets,
+            self.add_bundle,
+            entity,
+            table_row,
+            self.change_tick,
+            bundle,
+        );
+        self.entities.meta[entity.id as usize].location = location;
+
+        location
     }
 
+    /// # Safety
+    /// `T` must match this BundleInfo's type
     #[inline]
-    pub fn components(&self) -> &[ComponentId] {
+    pub unsafe fn spawn<T: Bundle>(&mut self, bundle: T) -> Entity {
-        &self.component_ids
+        let entity = self.entities.alloc();
-    }
+        // SAFE: entity is allocated (but non-existent), `T` matches this BundleInfo's type
-
+        self.spawn_non_existent(entity, bundle);
-    #[inline]
+        entity
-    pub fn storage_types(&self) -> &[StorageType] {
-        &self.storage_types
     }
 }
 
@@ -206,10 +563,12 @@ impl Bundles {
     ) -> &'a BundleInfo {
         let bundle_infos = &mut self.bundle_infos;
         let id = self.bundle_ids.entry(TypeId::of::<T>()).or_insert_with(|| {
-            let type_info = T::type_info();
+            let component_ids = T::component_ids(components);
             let id = BundleId(bundle_infos.len());
-            let bundle_info =
+            // SAFE: T::component_id ensures info was created
-                initialize_bundle(std::any::type_name::<T>(), &type_info, id, components);
+            let bundle_info = unsafe {
+                initialize_bundle(std::any::type_name::<T>(), component_ids, id, components)
+            };
             bundle_infos.push(bundle_info);
             id
         });
@@ -218,21 +577,21 @@ impl Bundles {
     }
 }
 
-fn initialize_bundle(
+/// # Safety
+///
+/// `component_id` must be valid [ComponentId]'s
+unsafe fn initialize_bundle(
     bundle_type_name: &'static str,
-    type_info: &[TypeInfo],
+    component_ids: Vec<ComponentId>,
     id: BundleId,
     components: &mut Components,
 ) -> BundleInfo {
-    let mut component_ids = Vec::new();
     let mut storage_types = Vec::new();
 
-    for type_info in type_info {
+    for &component_id in &component_ids {
-        let component_id = components.get_or_insert_with(type_info.type_id(), || type_info.clone());
+        // SAFE: component_id exists and is therefore valid
-        // SAFE: get_with_type_info ensures info was created
+        let component_info = components.get_info_unchecked(component_id);
-        let info = unsafe { components.get_info_unchecked(component_id) };
+        storage_types.push(component_info.storage_type());
-        component_ids.push(component_id);
-        storage_types.push(info.storage_type());
     }
 
     let mut deduped = component_ids.clone();

crates/bevy_ecs/src/component.rs

@@ -1,7 +1,3 @@
-mod type_info;
-
-pub use type_info::*;
-
 use crate::storage::SparseSetIndex;
 use std::{
     alloc::Layout,
@@ -56,15 +52,8 @@ impl Default for StorageType {
 
 #[derive(Debug)]
 pub struct ComponentInfo {
-    name: String,
     id: ComponentId,
-    type_id: Option<TypeId>,
+    descriptor: ComponentDescriptor,
-    // SAFETY: This must remain private. It must only be set to "true" if this component is
-    // actually Send + Sync
-    is_send_and_sync: bool,
-    layout: Layout,
-    drop: unsafe fn(*mut u8),
-    storage_type: StorageType,
 }
 
 impl ComponentInfo {
@@ -75,44 +64,36 @@ impl ComponentInfo {
 
     #[inline]
     pub fn name(&self) -> &str {
-        &self.name
+        &self.descriptor.name
     }
 
     #[inline]
     pub fn type_id(&self) -> Option<TypeId> {
-        self.type_id
+        self.descriptor.type_id
     }
 
     #[inline]
     pub fn layout(&self) -> Layout {
-        self.layout
+        self.descriptor.layout
     }
 
     #[inline]
     pub fn drop(&self) -> unsafe fn(*mut u8) {
-        self.drop
+        self.descriptor.drop
     }
 
     #[inline]
     pub fn storage_type(&self) -> StorageType {
-        self.storage_type
+        self.descriptor.storage_type
     }
 
     #[inline]
     pub fn is_send_and_sync(&self) -> bool {
-        self.is_send_and_sync
+        self.descriptor.is_send_and_sync
     }
 
     fn new(id: ComponentId, descriptor: ComponentDescriptor) -> Self {
-        ComponentInfo {
+        ComponentInfo { id, descriptor }
-            id,
-            name: descriptor.name,
-            storage_type: descriptor.storage_type,
-            type_id: descriptor.type_id,
-            is_send_and_sync: descriptor.is_send_and_sync,
-            drop: descriptor.drop,
-            layout: descriptor.layout,
-        }
     }
 }
 
@@ -142,6 +123,7 @@ impl SparseSetIndex for ComponentId {
     }
 }
 
+#[derive(Debug)]
 pub struct ComponentDescriptor {
     name: String,
     storage_type: StorageType,
@@ -154,6 +136,11 @@ pub struct ComponentDescriptor {
 }
 
 impl ComponentDescriptor {
+    // SAFETY: The pointer points to a valid value of type `T` and it is safe to drop this value.
+    unsafe fn drop_ptr<T>(x: *mut u8) {
+        x.cast::<T>().drop_in_place()
+    }
+
     pub fn new<T: Component>(storage_type: StorageType) -> Self {
         Self {
             name: std::any::type_name::<T>().to_string(),
@@ -161,7 +148,18 @@ impl ComponentDescriptor {
             is_send_and_sync: true,
             type_id: Some(TypeId::of::<T>()),
             layout: Layout::new::<T>(),
-            drop: TypeInfo::drop_ptr::<T>,
+            drop: Self::drop_ptr::<T>,
+        }
+    }
+
+    fn new_non_send<T: Any>(storage_type: StorageType) -> Self {
+        Self {
+            name: std::any::type_name::<T>().to_string(),
+            storage_type,
+            is_send_and_sync: false,
+            type_id: Some(TypeId::of::<T>()),
+            layout: Layout::new::<T>(),
+            drop: Self::drop_ptr::<T>,
         }
     }
 
@@ -181,19 +179,6 @@ impl ComponentDescriptor {
     }
 }
 
-impl From<TypeInfo> for ComponentDescriptor {
-    fn from(type_info: TypeInfo) -> Self {
-        Self {
-            name: type_info.type_name().to_string(),
-            storage_type: StorageType::default(),
-            is_send_and_sync: type_info.is_send_and_sync(),
-            type_id: Some(type_info.type_id()),
-            drop: type_info.drop(),
-            layout: type_info.layout(),
-        }
-    }
-}
-
 #[derive(Debug, Default)]
 pub struct Components {
     components: Vec<ComponentInfo>,
@@ -231,7 +216,12 @@ impl Components {
 
     #[inline]
     pub fn get_or_insert_id<T: Component>(&mut self) -> ComponentId {
-        self.get_or_insert_with(TypeId::of::<T>(), TypeInfo::of::<T>)
+        // SAFE: The [`ComponentDescriptor`] matches the [`TypeId`]
+        unsafe {
+            self.get_or_insert_with(TypeId::of::<T>(), || {
+                ComponentDescriptor::new::<T>(StorageType::default())
+            })
+        }
     }
 
     #[inline]
@@ -279,42 +269,58 @@ impl Components {
 
     #[inline]
     pub fn get_or_insert_resource_id<T: Component>(&mut self) -> ComponentId {
-        self.get_or_insert_resource_with(TypeId::of::<T>(), TypeInfo::of::<T>)
+        // SAFE: The [`ComponentDescriptor`] matches the [`TypeId`]
+        unsafe {
+            self.get_or_insert_resource_with(TypeId::of::<T>(), || {
+                ComponentDescriptor::new::<T>(StorageType::default())
+            })
+        }
     }
 
     #[inline]
     pub fn get_or_insert_non_send_resource_id<T: Any>(&mut self) -> ComponentId {
-        self.get_or_insert_resource_with(TypeId::of::<T>(), TypeInfo::of_non_send_and_sync::<T>)
+        // SAFE: The [`ComponentDescriptor`] matches the [`TypeId`]
+        unsafe {
+            self.get_or_insert_resource_with(TypeId::of::<T>(), || {
+                ComponentDescriptor::new_non_send::<T>(StorageType::default())
+            })
+        }
     }
 
+    /// # Safety
+    ///
+    /// The [`ComponentDescriptor`] must match the [`TypeId`]
     #[inline]
-    fn get_or_insert_resource_with(
+    unsafe fn get_or_insert_resource_with(
         &mut self,
         type_id: TypeId,
-        func: impl FnOnce() -> TypeInfo,
+        func: impl FnOnce() -> ComponentDescriptor,
     ) -> ComponentId {
         let components = &mut self.components;
         let index = self.resource_indices.entry(type_id).or_insert_with(|| {
-            let type_info = func();
+            let descriptor = func();
             let index = components.len();
-            components.push(ComponentInfo::new(ComponentId(index), type_info.into()));
+            components.push(ComponentInfo::new(ComponentId(index), descriptor));
             index
         });
 
         ComponentId(*index)
     }
 
+    /// # Safety
+    ///
+    /// The [`ComponentDescriptor`] must match the [`TypeId`]
     #[inline]
-    pub(crate) fn get_or_insert_with(
+    pub(crate) unsafe fn get_or_insert_with(
         &mut self,
         type_id: TypeId,
-        func: impl FnOnce() -> TypeInfo,
+        func: impl FnOnce() -> ComponentDescriptor,
     ) -> ComponentId {
         let components = &mut self.components;
         let index = self.indices.entry(type_id).or_insert_with(|| {
-            let type_info = func();
+            let descriptor = func();
             let index = components.len();
-            components.push(ComponentInfo::new(ComponentId(index), type_info.into()));
+            components.push(ComponentInfo::new(ComponentId(index), descriptor));
             index
         });
 

crates/bevy_ecs/src/component/type_info.rs

@@ -1,63 +0,0 @@
-use std::{alloc::Layout, any::TypeId};
-
-/// Metadata required to store a component.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct TypeInfo {
-    type_id: TypeId,
-    layout: Layout,
-    drop: unsafe fn(*mut u8),
-    type_name: &'static str,
-    is_send_and_sync: bool,
-}
-
-impl TypeInfo {
-    /// Metadata for `T`.
-    pub fn of<T: Send + Sync + 'static>() -> Self {
-        Self {
-            type_id: TypeId::of::<T>(),
-            layout: Layout::new::<T>(),
-            is_send_and_sync: true,
-            drop: Self::drop_ptr::<T>,
-            type_name: core::any::type_name::<T>(),
-        }
-    }
-
-    pub fn of_non_send_and_sync<T: 'static>() -> Self {
-        Self {
-            type_id: TypeId::of::<T>(),
-            layout: Layout::new::<T>(),
-            is_send_and_sync: false,
-            drop: Self::drop_ptr::<T>,
-            type_name: core::any::type_name::<T>(),
-        }
-    }
-
-    #[inline]
-    pub fn type_id(&self) -> TypeId {
-        self.type_id
-    }
-
-    #[inline]
-    pub fn layout(&self) -> Layout {
-        self.layout
-    }
-
-    #[inline]
-    pub fn drop(&self) -> unsafe fn(*mut u8) {
-        self.drop
-    }
-
-    #[inline]
-    pub fn is_send_and_sync(&self) -> bool {
-        self.is_send_and_sync
-    }
-
-    #[inline]
-    pub fn type_name(&self) -> &'static str {
-        self.type_name
-    }
-
-    pub(crate) unsafe fn drop_ptr<T>(x: *mut u8) {
-        x.cast::<T>().drop_in_place()
-    }
-}

crates/bevy_ecs/src/entity/mod.rs

@@ -34,6 +34,11 @@ pub enum AllocAtWithoutReplacement {
 
 impl Entity {
     /// Creates a new entity reference with a generation of 0.
+    ///
+    /// # Note
+    /// Spawning a specific `entity` value is rarely the right choice. Most apps should favor [`Commands::spawn`].
+    /// This method should generally only be used for sharing entities across apps, and only when they have a
+    /// scheme worked out to share an ID space (which doesn't happen by default).
     pub fn new(id: u32) -> Entity {
         Entity { id, generation: 0 }
     }
@@ -168,6 +173,7 @@ pub struct Entities {
     /// Once `flush()` is done, `free_cursor` will equal `pending.len()`.
     pending: Vec<u32>,
     free_cursor: AtomicI64,
+    /// Stores the number of free entities for [`len`](Entities::len)
     len: u32,
 }
 
@@ -318,7 +324,7 @@ impl Entities {
             AllocAtWithoutReplacement::DidNotExist
         } else {
             let current_meta = &mut self.meta[entity.id as usize];
-            if current_meta.location.archetype_id == ArchetypeId::invalid() {
+            if current_meta.location.archetype_id == ArchetypeId::INVALID {
                 AllocAtWithoutReplacement::DidNotExist
             } else if current_meta.generation == entity.generation {
                 AllocAtWithoutReplacement::Exists(current_meta.location)
@@ -364,12 +370,12 @@ impl Entities {
         }
     }
 
+    /// Returns true if the [`Entities`] contains [`entity`](Entity).
+    // This will return false for entities which have been freed, even if
+    // not reallocated since the generation is incremented in `free`
     pub fn contains(&self, entity: Entity) -> bool {
-        // Note that out-of-range IDs are considered to be "contained" because
+        self.resolve_from_id(entity.id())
-        // they must be reserved IDs that we haven't flushed yet.
+            .map_or(false, |e| e.generation() == entity.generation)
-        self.meta
-            .get(entity.id as usize)
-            .map_or(true, |meta| meta.generation == entity.generation)
     }
 
     pub fn clear(&mut self) {
@@ -384,7 +390,7 @@ impl Entities {
         if (entity.id as usize) < self.meta.len() {
             let meta = &self.meta[entity.id as usize];
             if meta.generation != entity.generation
-                || meta.location.archetype_id == ArchetypeId::invalid()
+                || meta.location.archetype_id == ArchetypeId::INVALID
             {
                 return None;
             }
@@ -394,31 +400,23 @@ impl Entities {
         }
     }
 
-    /// Panics if the given id would represent an index outside of `meta`.
+    /// Get the [`Entity`] with a given id, if it exists in this [`Entities`] collection
+    /// Returns `None` if this [`Entity`] is outside of the range of currently reserved Entities
     ///
-    /// # Safety
+    /// Note: This method may return [`Entities`](Entity) which are currently free
-    ///
+    /// Note that [`contains`](Entities::contains) will correctly return false for freed
-    /// Must only be called for currently allocated `id`s.
+    /// entities, since it checks the generation
-    pub unsafe fn resolve_unknown_gen(&self, id: u32) -> Entity {
+    pub fn resolve_from_id(&self, id: u32) -> Option<Entity> {
-        let meta_len = self.meta.len();
+        let idu = id as usize;
-
+        if let Some(&EntityMeta { generation, .. }) = self.meta.get(idu) {
-        if meta_len > id as usize {
+            Some(Entity { generation, id })
-            let meta = &self.meta[id as usize];
-            Entity {
-                generation: meta.generation,
-                id,
-            }
         } else {
-            // See if it's pending, but not yet flushed.
+            // `id` is outside of the meta list - check whether it is reserved but not yet flushed.
             let free_cursor = self.free_cursor.load(Ordering::Relaxed);
-            let num_pending = std::cmp::max(-free_cursor, 0) as usize;
+            // If this entity was manually created, then free_cursor might be positive
-
+            // Returning None handles that case correctly
-            if meta_len + num_pending > id as usize {
+            let num_pending = usize::try_from(-free_cursor).ok()?;
-                // Pending entities will have generation 0.
+            (idu < self.meta.len() + num_pending).then(|| Entity { generation: 0, id })
-                Entity { generation: 0, id }
-            } else {
-                panic!("entity id is out of range");
-            }
         }
     }
 
@@ -431,7 +429,7 @@ impl Entities {
     ///
     /// # Safety
     /// Flush _must_ set the entity location to the correct ArchetypeId for the given Entity
-    /// each time init is called. This _can_ be ArchetypeId::invalid(), provided the Entity has
+    /// each time init is called. This _can_ be ArchetypeId::INVALID, provided the Entity has
     /// not been assigned to an Archetype.
     pub unsafe fn flush(&mut self, mut init: impl FnMut(Entity, &mut EntityLocation)) {
         let free_cursor = self.free_cursor.get_mut();
@@ -476,7 +474,7 @@ impl Entities {
     pub fn flush_as_invalid(&mut self) {
         unsafe {
             self.flush(|_entity, location| {
-                location.archetype_id = ArchetypeId::invalid();
+                location.archetype_id = ArchetypeId::INVALID;
             })
         }
     }
@@ -502,8 +500,8 @@ impl EntityMeta {
     const EMPTY: EntityMeta = EntityMeta {
         generation: 0,
         location: EntityLocation {
-            archetype_id: ArchetypeId::invalid(),
+            archetype_id: ArchetypeId::INVALID,
-            index: usize::max_value(), // dummy value, to be filled in
+            index: usize::MAX, // dummy value, to be filled in
         },
     };
 }

crates/bevy_ecs/src/event.rs

@@ -68,7 +68,7 @@ enum State {
 /// [`Events::update`] exactly once per update/frame.
 ///
 /// [`Events::update_system`] is a system that does this, typically intialized automatically using
-/// [`AppBuilder::add_event`]. [EventReader]s are expected to read events from this collection at
+/// [`App::add_event`]. [EventReader]s are expected to read events from this collection at
 /// least once per loop/frame.
 /// Events will persist across a single frame boundary and so ordering of event producers and
 /// consumers is not critical (although poorly-planned ordering may cause accumulating lag).
@@ -115,9 +115,9 @@ enum State {
 /// An alternative call pattern would be to call [Events::update] manually across frames to control
 /// when events are cleared.
 /// This complicates consumption and risks ever-expanding memory usage if not cleaned up,
-/// but can be done by adding your event as a resource instead of using [`AppBuilder::add_event`].
+/// but can be done by adding your event as a resource instead of using [`App::add_event`].
 ///
-/// [`AppBuilder::add_event`]: https://docs.rs/bevy/*/bevy/app/struct.AppBuilder.html#method.add_event
+/// [`App::add_event`]: https://docs.rs/bevy/*/bevy/app/struct.App.html#method.add_event
 #[derive(Debug)]
 pub struct Events<T> {
     events_a: Vec<EventInstance<T>>,
@@ -151,21 +151,20 @@ fn map_instance_event<T>(event_instance: &EventInstance<T>) -> &T {
 
 /// Reads events of type `T` in order and tracks which events have already been read.
 #[derive(SystemParam)]
-pub struct EventReader<'s, 'w, T: Component> {
+pub struct EventReader<'w, 's, T: Component> {
     last_event_count: Local<'s, (usize, PhantomData<T>)>,
     events: Res<'w, Events<T>>,
 }
 
 /// Sends events of type `T`.
 #[derive(SystemParam)]
-pub struct EventWriter<'s, 'w, T: Component> {
+pub struct EventWriter<'w, 's, T: Component> {
     events: ResMut<'w, Events<T>>,
-    // TODO: this isn't ideal ... maybe the SystemParam derive can be smarter about world and state lifetimes?
     #[system_param(ignore)]
     marker: PhantomData<&'s usize>,
 }
 
-impl<'s, 'w, T: Component> EventWriter<'s, 'w, T> {
+impl<'w, 's, T: Component> EventWriter<'w, 's, T> {
     pub fn send(&mut self, event: T) {
         self.events.send(event);
     }
@@ -255,7 +254,7 @@ fn internal_event_reader<'a, T>(
     }
 }
 
-impl<'s, 'w, T: Component> EventReader<'s, 'w, T> {
+impl<'w, 's, T: Component> EventReader<'w, 's, T> {
     /// Iterates over the events this EventReader has not seen yet. This updates the EventReader's
     /// event counter, which means subsequent event reads will not include events that happened
     /// before now.

crates/bevy_ecs/src/lib.rs

@@ -22,7 +22,7 @@ pub mod prelude {
         change_detection::DetectChanges,
         entity::Entity,
         event::{EventReader, EventWriter},
-        query::{Added, ChangeTrackers, Changed, Or, QueryState, With, WithBundle, Without},
+        query::{Added, ChangeTrackers, Changed, Or, QueryState, With, Without},
         schedule::{
             AmbiguitySetLabel, ExclusiveSystemDescriptorCoercion, ParallelSystemDescriptorCoercion,
             RunCriteria, RunCriteriaDescriptorCoercion, RunCriteriaLabel, RunCriteriaPiping,
@@ -41,7 +41,7 @@ mod tests {
     use crate as bevy_ecs;
     use crate::{
         bundle::Bundle,
-        component::{Component, ComponentDescriptor, ComponentId, StorageType, TypeInfo},
+        component::{Component, ComponentDescriptor, ComponentId, StorageType},
         entity::Entity,
         query::{
             Added, ChangeTrackers, Changed, FilterFetch, FilteredAccess, With, Without, WorldQuery,
@@ -60,7 +60,9 @@ mod tests {
 
     #[derive(Debug, PartialEq, Eq)]
     struct A(usize);
+    #[derive(Debug, PartialEq, Eq)]
     struct B(usize);
+    #[derive(Debug, PartialEq, Eq)]
     struct C;
 
     #[derive(Clone, Debug)]
@@ -102,21 +104,26 @@ mod tests {
 
     #[test]
     fn bundle_derive() {
+        let mut world = World::new();
+
         #[derive(Bundle, PartialEq, Debug)]
         struct Foo {
             x: &'static str,
             y: i32,
         }
 
-        assert_eq!(
-            <Foo as Bundle>::type_info(),
-            vec![TypeInfo::of::<&'static str>(), TypeInfo::of::<i32>(),]
-        );
-
-        let mut world = World::new();
         world
             .register_component(ComponentDescriptor::new::<i32>(StorageType::SparseSet))
             .unwrap();
+
+        assert_eq!(
+            <Foo as Bundle>::component_ids(world.components_mut()),
+            vec![
+                world.components_mut().get_or_insert_id::<&'static str>(),
+                world.components_mut().get_or_insert_id::<i32>(),
+            ]
+        );
+
         let e1 = world.spawn().insert_bundle(Foo { x: "abc", y: 123 }).id();
         let e2 = world.spawn().insert_bundle(("def", 456, true)).id();
         assert_eq!(*world.get::<&str>(e1).unwrap(), "abc");
@@ -146,12 +153,12 @@ mod tests {
         }
 
         assert_eq!(
-            <Nested as Bundle>::type_info(),
+            <Nested as Bundle>::component_ids(world.components_mut()),
             vec![
-                TypeInfo::of::<usize>(),
+                world.components_mut().get_or_insert_id::<usize>(),
-                TypeInfo::of::<&'static str>(),
+                world.components_mut().get_or_insert_id::<&'static str>(),
-                TypeInfo::of::<i32>(),
+                world.components_mut().get_or_insert_id::<i32>(),
-                TypeInfo::of::<u8>(),
+                world.components_mut().get_or_insert_id::<u8>(),
             ]
         );
 
@@ -1393,4 +1400,89 @@ mod tests {
             "space between original entities and high entities is used for new entity ids"
         );
     }
+
+    #[test]
+    fn insert_or_spawn_batch() {
+        let mut world = World::default();
+        let e0 = world.spawn().insert(A(0)).id();
+        let e1 = Entity::new(1);
+
+        let values = vec![(e0, (B(0), C)), (e1, (B(1), C))];
+
+        world.insert_or_spawn_batch(values).unwrap();
+
+        assert_eq!(
+            world.get::<A>(e0),
+            Some(&A(0)),
+            "existing component was preserved"
+        );
+        assert_eq!(
+            world.get::<B>(e0),
+            Some(&B(0)),
+            "pre-existing entity received correct B component"
+        );
+        assert_eq!(
+            world.get::<B>(e1),
+            Some(&B(1)),
+            "new entity was spawned and received correct B component"
+        );
+        assert_eq!(
+            world.get::<C>(e0),
+            Some(&C),
+            "pre-existing entity received C component"
+        );
+        assert_eq!(
+            world.get::<C>(e1),
+            Some(&C),
+            "new entity was spawned and received C component"
+        );
+    }
+
+    #[test]
+    fn insert_or_spawn_batch_invalid() {
+        let mut world = World::default();
+        let e0 = world.spawn().insert(A(0)).id();
+        let e1 = Entity::new(1);
+        let e2 = world.spawn().id();
+        let invalid_e2 = Entity {
+            generation: 1,
+            id: e2.id,
+        };
+
+        let values = vec![(e0, (B(0), C)), (e1, (B(1), C)), (invalid_e2, (B(2), C))];
+
+        let result = world.insert_or_spawn_batch(values);
+
+        assert_eq!(
+            result,
+            Err(vec![invalid_e2]),
+            "e2 failed to be spawned or inserted into"
+        );
+
+        assert_eq!(
+            world.get::<A>(e0),
+            Some(&A(0)),
+            "existing component was preserved"
+        );
+        assert_eq!(
+            world.get::<B>(e0),
+            Some(&B(0)),
+            "pre-existing entity received correct B component"
+        );
+        assert_eq!(
+            world.get::<B>(e1),
+            Some(&B(1)),
+            "new entity was spawned and received correct B component"
+        );
+        assert_eq!(
+            world.get::<C>(e0),
+            Some(&C),
+            "pre-existing entity received C component"
+        );
+        assert_eq!(
+            world.get::<C>(e1),
+            Some(&C),
+            "new entity was spawned and received C component"
+        );
+    }
 }

crates/bevy_ecs/src/query/fetch.rs

@@ -137,6 +137,7 @@ impl WorldQuery for Entity {
 }
 
 /// The [`Fetch`] of [`Entity`].
+#[derive(Clone)]
 pub struct EntityFetch {
     entities: *const Entity,
 }
@@ -573,6 +574,7 @@ impl<T: WorldQuery> WorldQuery for Option<T> {
 }
 
 /// The [`Fetch`] of `Option<T>`.
+#[derive(Clone)]
 pub struct OptionFetch<T> {
     fetch: T,
     matches: bool,
@@ -807,6 +809,21 @@ pub struct ChangeTrackersFetch<T> {
     change_tick: u32,
 }
 
+impl<T> Clone for ChangeTrackersFetch<T> {
+    fn clone(&self) -> Self {
+        Self {
+            storage_type: self.storage_type,
+            table_ticks: self.table_ticks,
+            entity_table_rows: self.entity_table_rows,
+            entities: self.entities,
+            sparse_set: self.sparse_set,
+            marker: self.marker,
+            last_change_tick: self.last_change_tick,
+            change_tick: self.change_tick,
+        }
+    }
+}
+
 /// SAFETY: access is read only
 unsafe impl<T> ReadOnlyFetch for ChangeTrackersFetch<T> {}
 

crates/bevy_ecs/src/query/filter.rs

@@ -1,6 +1,5 @@
 use crate::{
     archetype::{Archetype, ArchetypeComponentId},
-    bundle::Bundle,
     component::{Component, ComponentId, ComponentTicks, StorageType},
     entity::Entity,
     query::{Access, Fetch, FetchState, FilteredAccess, WorldQuery},
@@ -12,7 +11,7 @@ use std::{cell::UnsafeCell, marker::PhantomData, ptr};
 
 /// Extension trait for [`Fetch`] containing methods used by query filters.
 /// This trait exists to allow "short circuit" behaviors for relevant query filter fetches.
-pub trait FilterFetch: for<'world, 'state> Fetch<'world, 'state> {
+pub trait FilterFetch: for<'w, 's> Fetch<'w, 's> {
     /// # Safety
     ///
     /// Must always be called _after_ [`Fetch::set_archetype`]. `archetype_index` must be in the range
@@ -282,106 +281,6 @@ impl<'w, 's, T: Component> Fetch<'w, 's> for WithoutFetch<T> {
     }
 }
 
-pub struct WithBundle<T: Bundle>(PhantomData<T>);
-
-impl<T: Bundle> WorldQuery for WithBundle<T> {
-    type Fetch = WithBundleFetch<T>;
-    type State = WithBundleState<T>;
-}
-
-pub struct WithBundleFetch<T: Bundle> {
-    is_dense: bool,
-    marker: PhantomData<T>,
-}
-
-pub struct WithBundleState<T: Bundle> {
-    component_ids: Vec<ComponentId>,
-    is_dense: bool,
-    marker: PhantomData<T>,
-}
-
-// SAFETY: no component access or archetype component access
-unsafe impl<T: Bundle> FetchState for WithBundleState<T> {
-    fn init(world: &mut World) -> Self {
-        let bundle_info = world.bundles.init_info::<T>(&mut world.components);
-        let components = &world.components;
-        Self {
-            component_ids: bundle_info.component_ids.clone(),
-            is_dense: !bundle_info.component_ids.iter().any(|id| unsafe {
-                components.get_info_unchecked(*id).storage_type() != StorageType::Table
-            }),
-            marker: PhantomData,
-        }
-    }
-
-    #[inline]
-    fn update_component_access(&self, access: &mut FilteredAccess<ComponentId>) {
-        for component_id in self.component_ids.iter().cloned() {
-            access.add_with(component_id);
-        }
-    }
-
-    #[inline]
-    fn update_archetype_component_access(
-        &self,
-        _archetype: &Archetype,
-        _access: &mut Access<ArchetypeComponentId>,
-    ) {
-    }
-
-    fn matches_archetype(&self, archetype: &Archetype) -> bool {
-        self.component_ids.iter().all(|id| archetype.contains(*id))
-    }
-
-    fn matches_table(&self, table: &Table) -> bool {
-        self.component_ids.iter().all(|id| table.has_column(*id))
-    }
-}
-
-impl<'w, 's, T: Bundle> Fetch<'w, 's> for WithBundleFetch<T> {
-    type Item = bool;
-    type State = WithBundleState<T>;
-
-    unsafe fn init(
-        _world: &World,
-        state: &Self::State,
-        _last_change_tick: u32,
-        _change_tick: u32,
-    ) -> Self {
-        Self {
-            is_dense: state.is_dense,
-            marker: PhantomData,
-        }
-    }
-
-    #[inline]
-    fn is_dense(&self) -> bool {
-        self.is_dense
-    }
-
-    #[inline]
-    unsafe fn set_table(&mut self, _state: &Self::State, _table: &Table) {}
-
-    #[inline]
-    unsafe fn set_archetype(
-        &mut self,
-        _state: &Self::State,
-        _archetype: &Archetype,
-        _tables: &Tables,
-    ) {
-    }
-
-    #[inline]
-    unsafe fn archetype_fetch(&mut self, _archetype_index: usize) -> bool {
-        true
-    }
-
-    #[inline]
-    unsafe fn table_fetch(&mut self, _table_row: usize) -> bool {
-        true
-    }
-}
-
 /// A filter that tests if any of the given filters apply.
 ///
 /// This is useful for example if a system with multiple components in a query only wants to run

crates/bevy_ecs/src/query/iter.rs

@@ -4,7 +4,7 @@ use crate::{
     storage::{TableId, Tables},
     world::World,
 };
-use std::{marker::PhantomData, mem::MaybeUninit};
+use std::mem::MaybeUninit;
 
 /// An [`Iterator`] over query results of a [`Query`](crate::system::Query).
 ///
@@ -217,7 +217,7 @@ where
     archetypes: &'w Archetypes,
     query_state: &'s QueryState<Q, F>,
     world: &'w World,
-    cursors: [QueryIterationCursor<'w, 's, Q, F>; K],
+    cursors: [QueryIterationCursor<'s, Q, F>; K],
 }
 
 impl<'w, 's, Q: WorldQuery, F: WorldQuery, const K: usize> QueryCombinationIter<'w, 's, Q, F, K>
@@ -239,7 +239,7 @@ where
         // There is no FromIterator on arrays, so instead initialize it manually with MaybeUninit
 
         // TODO: use MaybeUninit::uninit_array if it stabilizes
-        let mut cursors: [MaybeUninit<QueryIterationCursor<'w, 's, Q, F>>; K] =
+        let mut cursors: [MaybeUninit<QueryIterationCursor<'s, Q, F>>; K] =
             MaybeUninit::uninit().assume_init();
         for (i, cursor) in cursors.iter_mut().enumerate() {
             match i {
@@ -259,8 +259,8 @@ where
         }
 
         // TODO: use MaybeUninit::array_assume_init if it stabilizes
-        let cursors: [QueryIterationCursor<'w, 's, Q, F>; K] =
+        let cursors: [QueryIterationCursor<'s, Q, F>; K] =
-            (&cursors as *const _ as *const [QueryIterationCursor<'w, 's, Q, F>; K]).read();
+            (&cursors as *const _ as *const [QueryIterationCursor<'s, Q, F>; K]).read();
 
         QueryCombinationIter {
             world,
@@ -277,9 +277,9 @@ where
     /// references to the same component, leading to unique reference aliasing.
     ///.
     /// It is always safe for shared access.
-    unsafe fn fetch_next_aliased_unchecked(
+    unsafe fn fetch_next_aliased_unchecked<'a>(
         &mut self,
-    ) -> Option<[<Q::Fetch as Fetch<'w, 's>>::Item; K]>
+    ) -> Option<[<Q::Fetch as Fetch<'a, 's>>::Item; K]>
     where
         Q::Fetch: Clone,
         F::Fetch: Clone,
@@ -309,7 +309,7 @@ where
         }
 
         // TODO: use MaybeUninit::uninit_array if it stabilizes
-        let mut values: [MaybeUninit<<Q::Fetch as Fetch<'w, 's>>::Item>; K] =
+        let mut values: [MaybeUninit<<Q::Fetch as Fetch<'a, 's>>::Item>; K] =
             MaybeUninit::uninit().assume_init();
 
         for (value, cursor) in values.iter_mut().zip(&mut self.cursors) {
@@ -317,15 +317,15 @@ where
         }
 
         // TODO: use MaybeUninit::array_assume_init if it stabilizes
-        let values: [<Q::Fetch as Fetch<'w, 's>>::Item; K] =
+        let values: [<Q::Fetch as Fetch<'a, 's>>::Item; K] =
-            (&values as *const _ as *const [<Q::Fetch as Fetch<'w, 's>>::Item; K]).read();
+            (&values as *const _ as *const [<Q::Fetch as Fetch<'a, 's>>::Item; K]).read();
 
         Some(values)
     }
 
     /// Get next combination of queried components
     #[inline]
-    pub fn fetch_next(&mut self) -> Option<[<Q::Fetch as Fetch<'w, 's>>::Item; K]>
+    pub fn fetch_next(&mut self) -> Option<[<Q::Fetch as Fetch<'_, 's>>::Item; K]>
     where
         Q::Fetch: Clone,
         F::Fetch: Clone,
@@ -400,7 +400,7 @@ impl<'w, 's, Q: WorldQuery> ExactSizeIterator for QueryIter<'w, 's, Q, ()> {
     }
 }
 
-struct QueryIterationCursor<'w, 's, Q: WorldQuery, F: WorldQuery> {
+struct QueryIterationCursor<'s, Q: WorldQuery, F: WorldQuery> {
     table_id_iter: std::slice::Iter<'s, TableId>,
     archetype_id_iter: std::slice::Iter<'s, ArchetypeId>,
     fetch: Q::Fetch,
@@ -408,10 +408,9 @@ struct QueryIterationCursor<'w, 's, Q: WorldQuery, F: WorldQuery> {
     current_len: usize,
     current_index: usize,
     is_dense: bool,
-    marker: PhantomData<&'w usize>,
 }
 
-impl<'w, 's, Q: WorldQuery, F: WorldQuery> Clone for QueryIterationCursor<'w, 's, Q, F>
+impl<'s, Q: WorldQuery, F: WorldQuery> Clone for QueryIterationCursor<'s, Q, F>
 where
     Q::Fetch: Clone,
     F::Fetch: Clone,
@@ -425,12 +424,11 @@ where
             current_len: self.current_len,
             current_index: self.current_index,
             is_dense: self.is_dense,
-            marker: PhantomData,
         }
     }
 }
 
-impl<'w, 's, Q: WorldQuery, F: WorldQuery> QueryIterationCursor<'w, 's, Q, F>
+impl<'s, Q: WorldQuery, F: WorldQuery> QueryIterationCursor<'s, Q, F>
 where
     F::Fetch: FilterFetch,
 {
@@ -473,13 +471,12 @@ where
             archetype_id_iter: query_state.matched_archetype_ids.iter(),
             current_len: 0,
             current_index: 0,
-            marker: PhantomData,
         }
     }
 
     /// retrieve item returned from most recent `next` call again.
     #[inline]
-    unsafe fn peek_last(&mut self) -> Option<<Q::Fetch as Fetch<'w, 's>>::Item> {
+    unsafe fn peek_last<'w>(&mut self) -> Option<<Q::Fetch as Fetch<'w, 's>>::Item> {
         if self.current_index > 0 {
             if self.is_dense {
                 Some(self.fetch.table_fetch(self.current_index - 1))
@@ -495,7 +492,7 @@ where
     // QueryIter, QueryIterationCursor, QueryState::for_each_unchecked_manual, QueryState::par_for_each_unchecked_manual
     // We can't currently reuse QueryIterationCursor in QueryIter for performance reasons. See #1763 for context.
     #[inline(always)]
-    unsafe fn next(
+    unsafe fn next<'w>(
         &mut self,
         tables: &'w Tables,
         archetypes: &'w Archetypes,

crates/bevy_ecs/src/query/state.rs

@@ -13,6 +13,7 @@ use bevy_tasks::TaskPool;
 use fixedbitset::FixedBitSet;
 use thiserror::Error;
 
+/// Provides scoped access to a [`World`] state according to a given [`WorldQuery`] and query filter.
 pub struct QueryState<Q: WorldQuery, F: WorldQuery = ()>
 where
     F::Fetch: FilterFetch,
@@ -35,6 +36,7 @@ impl<Q: WorldQuery, F: WorldQuery> QueryState<Q, F>
 where
     F::Fetch: FilterFetch,
 {
+    /// Creates a new [`QueryState`] from a given [`World`] and inherits the result of `world.id()`.
     pub fn new(world: &mut World) -> Self {
         let fetch_state = <Q::State as FetchState>::init(world);
         let filter_state = <F::State as FetchState>::init(world);
@@ -68,6 +70,7 @@ where
         state
     }
 
+    /// Checks if the query is empty for the given [`World`], where the last change and current tick are given.
     #[inline]
     pub fn is_empty(&self, world: &World, last_change_tick: u32, change_tick: u32) -> bool {
         // SAFE: the iterator is instantly consumed via `none_remaining` and the implementation of
@@ -78,6 +81,12 @@ where
         }
     }
 
+    /// Takes a query for the given [`World`], checks if the given world is the same as the query, and
+    /// generates new archetypes for the given world.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `world.id()` does not equal the current [`QueryState`] internal id.
     pub fn update_archetypes(&mut self, world: &World) {
         self.validate_world(world);
         let archetypes = world.archetypes();
@@ -98,6 +107,7 @@ where
         }
     }
 
+    /// Creates a new [`Archetype`].
     pub fn new_archetype(&mut self, archetype: &Archetype) {
         if self.fetch_state.matches_archetype(archetype)
             && self.filter_state.matches_archetype(archetype)
@@ -121,6 +131,9 @@ where
         }
     }
 
+    /// Gets the query result for the given [`World`] and [`Entity`].
+    ///
+    /// This can only be called for read-only queries, see [`Self::get_mut`] for write-queries.
     #[inline]
     pub fn get<'w, 's>(
         &'s mut self,
@@ -134,6 +147,17 @@ where
         unsafe { self.get_unchecked(world, entity) }
     }
 
+    /// Gets the query result for the given [`World`] and [`Entity`].
+    #[inline]
+    pub fn get_mut<'w, 's>(
+        &'s mut self,
+        world: &'w mut World,
+        entity: Entity,
+    ) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QueryEntityError> {
+        // SAFETY: query has unique world access
+        unsafe { self.get_unchecked(world, entity) }
+    }
+
     #[inline]
     pub fn get_manual<'w, 's>(
         &'s self,
@@ -155,16 +179,8 @@ where
         }
     }
 
-    #[inline]
+    /// Gets the query result for the given [`World`] and [`Entity`].
-    pub fn get_mut<'w, 's>(
+    ///
-        &'s mut self,
-        world: &'w mut World,
-        entity: Entity,
-    ) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QueryEntityError> {
-        // SAFETY: query has unique world access
-        unsafe { self.get_unchecked(world, entity) }
-    }
-
     /// # Safety
     ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
@@ -184,7 +200,11 @@ where
         )
     }
 
+    /// Gets the query result for the given [`World`] and [`Entity`], where the last change and
+    /// the current change tick are given.
+    ///
     /// # Safety
+    ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
     /// have unique access to the components they query.
     pub unsafe fn get_unchecked_manual<'w, 's>(
@@ -219,6 +239,9 @@ where
         }
     }
 
+    /// Returns an [`Iterator`] over the query results for the given [`World`].
+    ///
+    /// This can only be called for read-only queries, see [`Self::iter_mut`] for write-queries.
     #[inline]
     pub fn iter<'w, 's>(&'s mut self, world: &'w World) -> QueryIter<'w, 's, Q, F>
     where
@@ -228,6 +251,13 @@ where
         unsafe { self.iter_unchecked(world) }
     }
 
+    /// Returns an [`Iterator`] over the query results for the given [`World`].
+    #[inline]
+    pub fn iter_mut<'w, 's>(&'s mut self, world: &'w mut World) -> QueryIter<'w, 's, Q, F> {
+        // SAFETY: query has unique world access
+        unsafe { self.iter_unchecked(world) }
+    }
+
     #[inline]
     pub fn iter_manual<'w, 's>(&'s self, world: &'w World) -> QueryIter<'w, 's, Q, F>
     where
@@ -240,12 +270,16 @@ where
         }
     }
 
-    #[inline]
+    /// Returns an [`Iterator`] over all possible combinations of `K` query results without repetition.
-    pub fn iter_mut<'w, 's>(&'s mut self, world: &'w mut World) -> QueryIter<'w, 's, Q, F> {
+    /// This can only be called for read-only queries.
-        // SAFETY: query has unique world access
+    ///
-        unsafe { self.iter_unchecked(world) }
+    ///  For permutations of size K of query returning N results, you will get:
-    }
+    /// - if K == N: one permutation of all query results
-
+    /// - if K < N: all possible K-sized combinations of query results, without repetition
+    /// - if K > N: empty set (no K-sized combinations exist)
+    ///
+    /// This can only be called for read-only queries, see [`Self::iter_combinations_mut`] for
+    /// write-queries.
     #[inline]
     pub fn iter_combinations<'w, 's, const K: usize>(
         &'s mut self,
@@ -258,6 +292,13 @@ where
         unsafe { self.iter_combinations_unchecked(world) }
     }
 
+    /// Iterates over all possible combinations of `K` query results for the given [`World`]
+    /// without repetition.
+    ///
+    ///  For permutations of size K of query returning N results, you will get:
+    /// - if K == N: one permutation of all query results
+    /// - if K < N: all possible K-sized combinations of query results, without repetition
+    /// - if K > N: empty set (no K-sized combinations exist)
     #[inline]
     pub fn iter_combinations_mut<'w, 's, const K: usize>(
         &'s mut self,
@@ -267,6 +308,8 @@ where
         unsafe { self.iter_combinations_unchecked(world) }
     }
 
+    /// Returns an [`Iterator`] over the query results for the given [`World`].
+    ///
     /// # Safety
     ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
@@ -280,6 +323,10 @@ where
         self.iter_unchecked_manual(world, world.last_change_tick(), world.read_change_tick())
     }
 
+    /// Returns an [`Iterator`] over all possible combinations of `K` query results for the
+    /// given [`World`] without repetition.
+    /// This can only be called for read-only queries.
+    ///
     /// # Safety
     ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
@@ -297,7 +344,11 @@ where
         )
     }
 
+    /// Returns an [`Iterator`] for the given [`World`], where the last change and
+    /// the current change tick are given.
+    ///
     /// # Safety
+    ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
     /// have unique access to the components they query.
     /// This does not validate that `world.id()` matches `self.world_id`. Calling this on a `world`
@@ -312,7 +363,12 @@ where
         QueryIter::new(world, self, last_change_tick, change_tick)
     }
 
+    /// Returns an [`Iterator`] over all possible combinations of `K` query results for the
+    /// given [`World`] without repetition.
+    /// This can only be called for read-only queries.
+    ///
     /// # Safety
+    ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
     /// have unique access to the components they query.
     /// This does not validate that `world.id()` matches `self.world_id`. Calling this on a `world`
@@ -327,6 +383,10 @@ where
         QueryCombinationIter::new(world, self, last_change_tick, change_tick)
     }
 
+    /// Runs `func` on each query result for the given [`World`]. This is faster than the equivalent
+    /// iter() method, but cannot be chained like a normal [`Iterator`].
+    ///
+    /// This can only be called for read-only queries, see [`Self::for_each_mut`] for write-queries.
     #[inline]
     pub fn for_each<'w, 's>(
         &'s mut self,
@@ -341,6 +401,8 @@ where
         }
     }
 
+    /// Runs `func` on each query result for the given [`World`]. This is faster than the equivalent
+    /// iter_mut() method, but cannot be chained like a normal [`Iterator`].
     #[inline]
     pub fn for_each_mut<'w, 's>(
         &'s mut self,
@@ -353,6 +415,11 @@ where
         }
     }
 
+    /// Runs `func` on each query result for the given [`World`]. This is faster than the equivalent
+    /// iter() method, but cannot be chained like a normal [`Iterator`].
+    ///
+    /// This can only be called for read-only queries.
+    ///
     /// # Safety
     ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
@@ -372,6 +439,10 @@ where
         );
     }
 
+    /// Runs `func` on each query result in parallel using the given `task_pool`.
+    ///
+    /// This can only be called for read-only queries, see [`Self::par_for_each_mut`] for
+    /// write-queries.
     #[inline]
     pub fn par_for_each<'w, 's>(
         &'s mut self,
@@ -388,6 +459,7 @@ where
         }
     }
 
+    /// Runs `func` on each query result in parallel using the given `task_pool`.
     #[inline]
     pub fn par_for_each_mut<'w, 's>(
         &'s mut self,
@@ -402,6 +474,10 @@ where
         }
     }
 
+    /// Runs `func` on each query result in parallel using the given `task_pool`.
+    ///
+    /// This can only be called for read-only queries.
+    ///
     /// # Safety
     ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
@@ -425,6 +501,10 @@ where
         );
     }
 
+    /// Runs `func` on each query result for the given [`World`], where the last change and
+    /// the current change tick are given. This is faster than the equivalent
+    /// iter() method, but cannot be chained like a normal [`Iterator`].
+    ///
     /// # Safety
     ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries
@@ -477,6 +557,10 @@ where
         }
     }
 
+    /// Runs `func` on each query result in parallel for the given [`World`], where the last change and
+    /// the current change tick are given. This is faster than the equivalent
+    /// iter() method, but cannot be chained like a normal [`Iterator`].
+    ///
     /// # Safety
     ///
     /// This does not check for mutable query correctness. To be safe, make sure mutable queries

crates/bevy_ecs/src/reflect.rs

@@ -10,6 +10,7 @@ use bevy_reflect::{impl_reflect_value, FromType, Reflect, ReflectDeserialize};
 pub struct ReflectComponent {
     add_component: fn(&mut World, Entity, &dyn Reflect),
     apply_component: fn(&mut World, Entity, &dyn Reflect),
+    remove_component: fn(&mut World, Entity),
     reflect_component: fn(&World, Entity) -> Option<&dyn Reflect>,
     reflect_component_mut: unsafe fn(&World, Entity) -> Option<ReflectMut>,
     copy_component: fn(&World, &mut World, Entity, Entity),
@@ -24,6 +25,10 @@ impl ReflectComponent {
         (self.apply_component)(world, entity, component);
     }
 
+    pub fn remove_component(&self, world: &mut World, entity: Entity) {
+        (self.remove_component)(world, entity);
+    }
+
     pub fn reflect_component<'a>(
         &self,
         world: &'a World,
@@ -83,6 +88,9 @@ impl<C: Component + Reflect + FromWorld> FromType<C> for ReflectComponent {
                 let mut component = world.get_mut::<C>(entity).unwrap();
                 component.apply(reflected_component);
             },
+            remove_component: |world, entity| {
+                world.entity_mut(entity).remove::<C>();
+            },
             copy_component: |source_world, destination_world, source_entity, destination_entity| {
                 let source_component = source_world.get::<C>(source_entity).unwrap();
                 let mut destination_component = C::from_world(destination_world);

crates/bevy_ecs/src/schedule/executor_parallel.rs

@@ -316,7 +316,7 @@ mod tests {
     use super::SchedulingEvent::{self, *};
     use crate::{
         schedule::{SingleThreadedExecutor, Stage, SystemStage},
-        system::{IntoSystem, NonSend, Query, Res, ResMut},
+        system::{NonSend, Query, Res, ResMut},
         world::World,
     };
     use async_channel::Receiver;
@@ -338,9 +338,9 @@ mod tests {
         let mut world = World::new();
         fn wants_for_nothing() {}
         let mut stage = SystemStage::parallel()
-            .with_system(wants_for_nothing.system())
+            .with_system(wants_for_nothing)
-            .with_system(wants_for_nothing.system())
+            .with_system(wants_for_nothing)
-            .with_system(wants_for_nothing.system());
+            .with_system(wants_for_nothing);
         stage.run(&mut world);
         stage.run(&mut world);
         assert_eq!(
@@ -356,24 +356,24 @@ mod tests {
         fn wants_mut(_: ResMut<usize>) {}
         fn wants_ref(_: Res<usize>) {}
         let mut stage = SystemStage::parallel()
-            .with_system(wants_mut.system())
+            .with_system(wants_mut)
-            .with_system(wants_mut.system());
+            .with_system(wants_mut);
         stage.run(&mut world);
         assert_eq!(
             receive_events(&world),
             vec![StartedSystems(1), StartedSystems(1),]
         );
         let mut stage = SystemStage::parallel()
-            .with_system(wants_mut.system())
+            .with_system(wants_mut)
-            .with_system(wants_ref.system());
+            .with_system(wants_ref);
         stage.run(&mut world);
         assert_eq!(
             receive_events(&world),
             vec![StartedSystems(1), StartedSystems(1),]
         );
         let mut stage = SystemStage::parallel()
-            .with_system(wants_ref.system())
+            .with_system(wants_ref)
-            .with_system(wants_ref.system());
+            .with_system(wants_ref);
         stage.run(&mut world);
         assert_eq!(receive_events(&world), vec![StartedSystems(2),]);
     }
@@ -385,24 +385,24 @@ mod tests {
         fn wants_mut(_: Query<&mut usize>) {}
         fn wants_ref(_: Query<&usize>) {}
         let mut stage = SystemStage::parallel()
-            .with_system(wants_mut.system())
+            .with_system(wants_mut)
-            .with_system(wants_mut.system());
+            .with_system(wants_mut);
         stage.run(&mut world);
         assert_eq!(
             receive_events(&world),
             vec![StartedSystems(1), StartedSystems(1),]
         );
         let mut stage = SystemStage::parallel()
-            .with_system(wants_mut.system())
+            .with_system(wants_mut)
-            .with_system(wants_ref.system());
+            .with_system(wants_ref);
         stage.run(&mut world);
         assert_eq!(
             receive_events(&world),
             vec![StartedSystems(1), StartedSystems(1),]
         );
         let mut stage = SystemStage::parallel()
-            .with_system(wants_ref.system())
+            .with_system(wants_ref)
-            .with_system(wants_ref.system());
+            .with_system(wants_ref);
         stage.run(&mut world);
         assert_eq!(receive_events(&world), vec![StartedSystems(2),]);
         let mut world = World::new();
@@ -410,8 +410,8 @@ mod tests {
         fn wants_mut_usize(_: Query<(&mut usize, &f32)>) {}
         fn wants_mut_u32(_: Query<(&mut u32, &f32)>) {}
         let mut stage = SystemStage::parallel()
-            .with_system(wants_mut_usize.system())
+            .with_system(wants_mut_usize)
-            .with_system(wants_mut_u32.system());
+            .with_system(wants_mut_u32);
         stage.run(&mut world);
         assert_eq!(receive_events(&world), vec![StartedSystems(2),]);
     }
@@ -426,12 +426,12 @@ mod tests {
         }
         fn empty() {}
         let mut stage = SystemStage::parallel()
-            .with_system(non_send.system())
+            .with_system(non_send)
-            .with_system(non_send.system())
+            .with_system(non_send)
-            .with_system(empty.system())
+            .with_system(empty)
-            .with_system(empty.system())
+            .with_system(empty)
-            .with_system(non_send.system())
+            .with_system(non_send)
-            .with_system(non_send.system());
+            .with_system(non_send);
         stage.run(&mut world);
         assert_eq!(
             receive_events(&world),

crates/bevy_ecs/src/schedule/label.rs

@@ -1,15 +1,115 @@
 pub use bevy_ecs_macros::{AmbiguitySetLabel, RunCriteriaLabel, StageLabel, SystemLabel};
 
-use bevy_utils::define_label;
+use std::{
+    any::Any,
+    borrow::Cow,
+    fmt::Debug,
+    hash::{Hash, Hasher},
+};
 
-define_label!(StageLabel);
+pub trait DynEq: Any {
+    fn as_any(&self) -> &dyn Any;
+
+    fn dyn_eq(&self, other: &dyn DynEq) -> bool;
+}
+
+impl<T> DynEq for T
+where
+    T: Any + Eq,
+{
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn dyn_eq(&self, other: &dyn DynEq) -> bool {
+        if let Some(other) = other.as_any().downcast_ref::<T>() {
+            return self == other;
+        }
+        false
+    }
+}
+
+pub trait DynHash: DynEq {
+    fn as_dyn_eq(&self) -> &dyn DynEq;
+
+    fn dyn_hash(&self, state: &mut dyn Hasher);
+}
+
+impl<T> DynHash for T
+where
+    T: DynEq + Hash,
+{
+    fn as_dyn_eq(&self) -> &dyn DynEq {
+        self
+    }
+
+    fn dyn_hash(&self, mut state: &mut dyn Hasher) {
+        T::hash(self, &mut state);
+        self.type_id().hash(&mut state);
+    }
+}
+
+pub trait StageLabel: DynHash + Debug + Send + Sync + 'static {
+    #[doc(hidden)]
+    fn dyn_clone(&self) -> Box<dyn StageLabel>;
+}
 pub(crate) type BoxedStageLabel = Box<dyn StageLabel>;
 
-define_label!(SystemLabel);
+pub trait SystemLabel: DynHash + Debug + Send + Sync + 'static {
+    #[doc(hidden)]
+    fn dyn_clone(&self) -> Box<dyn SystemLabel>;
+}
 pub(crate) type BoxedSystemLabel = Box<dyn SystemLabel>;
 
-define_label!(AmbiguitySetLabel);
+pub trait AmbiguitySetLabel: DynHash + Debug + Send + Sync + 'static {
+    #[doc(hidden)]
+    fn dyn_clone(&self) -> Box<dyn AmbiguitySetLabel>;
+}
 pub(crate) type BoxedAmbiguitySetLabel = Box<dyn AmbiguitySetLabel>;
 
-define_label!(RunCriteriaLabel);
+pub trait RunCriteriaLabel: DynHash + Debug + Send + Sync + 'static {
+    #[doc(hidden)]
+    fn dyn_clone(&self) -> Box<dyn RunCriteriaLabel>;
+}
 pub(crate) type BoxedRunCriteriaLabel = Box<dyn RunCriteriaLabel>;
+
+macro_rules! impl_label {
+    ($trait_name:ident) => {
+        impl PartialEq for dyn $trait_name {
+            fn eq(&self, other: &Self) -> bool {
+                self.dyn_eq(other.as_dyn_eq())
+            }
+        }
+
+        impl Eq for dyn $trait_name {}
+
+        impl Hash for dyn $trait_name {
+            fn hash<H: Hasher>(&self, state: &mut H) {
+                self.dyn_hash(state);
+            }
+        }
+
+        impl Clone for Box<dyn $trait_name> {
+            fn clone(&self) -> Self {
+                self.dyn_clone()
+            }
+        }
+
+        impl $trait_name for Cow<'static, str> {
+            fn dyn_clone(&self) -> Box<dyn $trait_name> {
+                Box::new(self.clone())
+            }
+        }
+
+        impl $trait_name for &'static str {
+            fn dyn_clone(&self) -> Box<dyn $trait_name> {
+                Box::new(<&str>::clone(self))
+            }
+        }
+    };
+}
+
+impl_label!(StageLabel);
+impl_label!(SystemLabel);
+impl_label!(AmbiguitySetLabel);
+impl_label!(RunCriteriaLabel);

crates/bevy_ecs/src/schedule/mod.rs

@@ -22,10 +22,7 @@ pub use system_set::*;
 
 use std::fmt::Debug;
 
-use crate::{
+use crate::{system::System, world::World};
-    system::{IntoSystem, System},
-    world::World,
-};
 use bevy_utils::HashMap;
 
 #[derive(Default)]
@@ -79,7 +76,7 @@ impl Schedule {
         &mut self,
         system: S,
     ) -> &mut Self {
-        self.run_criteria.set(Box::new(system.system()));
+        self.run_criteria.set(Box::new(system));
         self
     }
 

crates/bevy_ecs/src/schedule/run_criteria.rs

@@ -61,12 +61,12 @@ impl Default for BoxedRunCriteria {
 }
 
 impl BoxedRunCriteria {
-    pub fn set(&mut self, criteria_system: BoxedSystem<(), ShouldRun>) {
+    pub(crate) fn set(&mut self, criteria_system: BoxedSystem<(), ShouldRun>) {
         self.criteria_system = Some(criteria_system);
         self.initialized = false;
     }
 
-    pub fn should_run(&mut self, world: &mut World) -> ShouldRun {
+    pub(crate) fn should_run(&mut self, world: &mut World) -> ShouldRun {
         if let Some(ref mut run_criteria) = self.criteria_system {
             if !self.initialized {
                 run_criteria.initialize(world);
@@ -99,16 +99,16 @@ pub(crate) enum RunCriteriaInner {
 }
 
 pub(crate) struct RunCriteriaContainer {
-    pub should_run: ShouldRun,
+    pub(crate) should_run: ShouldRun,
-    pub inner: RunCriteriaInner,
+    pub(crate) inner: RunCriteriaInner,
-    pub label: Option<BoxedRunCriteriaLabel>,
+    pub(crate) label: Option<BoxedRunCriteriaLabel>,
-    pub before: Vec<BoxedRunCriteriaLabel>,
+    pub(crate) before: Vec<BoxedRunCriteriaLabel>,
-    pub after: Vec<BoxedRunCriteriaLabel>,
+    pub(crate) after: Vec<BoxedRunCriteriaLabel>,
     archetype_generation: ArchetypeGeneration,
 }
 
 impl RunCriteriaContainer {
-    pub fn from_descriptor(descriptor: RunCriteriaDescriptor) -> Self {
+    pub(crate) fn from_descriptor(descriptor: RunCriteriaDescriptor) -> Self {
         Self {
             should_run: ShouldRun::Yes,
             inner: match descriptor.system {
@@ -122,21 +122,21 @@ impl RunCriteriaContainer {
         }
     }
 
-    pub fn name(&self) -> Cow<'static, str> {
+    pub(crate) fn name(&self) -> Cow<'static, str> {
         match &self.inner {
             RunCriteriaInner::Single(system) => system.name(),
             RunCriteriaInner::Piped { system, .. } => system.name(),
         }
     }
 
-    pub fn initialize(&mut self, world: &mut World) {
+    pub(crate) fn initialize(&mut self, world: &mut World) {
         match &mut self.inner {
             RunCriteriaInner::Single(system) => system.initialize(world),
             RunCriteriaInner::Piped { system, .. } => system.initialize(world),
         }
     }
 
-    pub fn update_archetypes(&mut self, world: &World) {
+    pub(crate) fn update_archetypes(&mut self, world: &World) {
         let archetypes = world.archetypes();
         let new_generation = archetypes.generation();
         let old_generation = std::mem::replace(&mut self.archetype_generation, new_generation);

crates/bevy_ecs/src/schedule/stage.rs

@@ -1,5 +1,6 @@
 use crate::{
     component::ComponentId,
+    prelude::IntoSystem,
     schedule::{
         graph_utils::{self, DependencyGraphError},
         BoxedRunCriteria, BoxedRunCriteriaLabel, BoxedSystemLabel, DuplicateLabelStrategy,
@@ -8,7 +9,6 @@ use crate::{
         RunCriteriaDescriptor, RunCriteriaDescriptorOrLabel, RunCriteriaInner, ShouldRun,
         SingleThreadedExecutor, SystemContainer, SystemDescriptor, SystemSet,
     },
-    system::System,
     world::{World, WorldId},
 };
 use bevy_utils::{tracing::info, HashMap, HashSet};
@@ -26,7 +26,7 @@ pub trait Stage: Downcast + Send + Sync {
 
 impl_downcast!(Stage);
 
-/// When this resource is present in the `AppBuilder`'s `Resources`,
+/// When this resource is present in the `App`'s `Resources`,
 /// each `SystemStage` will log a report containing
 /// pairs of systems with ambiguous execution order.
 ///
@@ -83,6 +83,7 @@ pub struct SystemStage {
     uninitialized_parallel: Vec<usize>,
     /// Saves the value of the World change_tick during the last tick check
     last_tick_check: u32,
+    /// If true, buffers will be automatically applied at the end of the stage. If false, buffers must be manually applied.
     apply_buffers: bool,
 }
 
@@ -301,16 +302,19 @@ impl SystemStage {
         self
     }
 
-    pub fn with_run_criteria<S: System<In = (), Out = ShouldRun>>(mut self, system: S) -> Self {
+    pub fn with_run_criteria<Param, S: IntoSystem<(), ShouldRun, Param>>(
-        self.set_run_criteria(system);
+        mut self,
+        system: S,
+    ) -> Self {
+        self.set_run_criteria(system.system());
         self
     }
 
-    pub fn set_run_criteria<S: System<In = (), Out = ShouldRun>>(
+    pub fn set_run_criteria<Param, S: IntoSystem<(), ShouldRun, Param>>(
         &mut self,
         system: S,
     ) -> &mut Self {
-        self.stage_run_criteria.set(Box::new(system));
+        self.stage_run_criteria.set(Box::new(system.system()));
         self
     }
 
@@ -919,14 +923,8 @@ mod tests {
         move |world| world.get_resource_mut::<Vec<usize>>().unwrap().push(tag)
     }
 
-    // This is silly. https://github.com/bevyengine/bevy/issues/1029
+    fn make_parallel(tag: usize) -> impl FnMut(ResMut<Vec<usize>>) {
-    macro_rules! make_parallel {
+        move |mut resource: ResMut<Vec<usize>>| resource.push(tag)
-        ($tag:expr) => {{
-            fn parallel(mut resource: ResMut<Vec<usize>>) {
-                resource.push($tag)
-            }
-            parallel
-        }};
     }
 
     fn every_other_time(mut has_ran: Local<bool>) -> ShouldRun {
@@ -944,7 +942,7 @@ mod tests {
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
             .with_system(make_exclusive(0).exclusive_system().at_start())
-            .with_system(make_parallel!(1).system())
+            .with_system(make_parallel(1))
             .with_system(make_exclusive(2).exclusive_system().before_commands())
             .with_system(make_exclusive(3).exclusive_system().at_end());
         stage.run(&mut world);
@@ -963,7 +961,7 @@ mod tests {
         let mut stage = SystemStage::parallel()
             .with_system(make_exclusive(2).exclusive_system().before_commands())
             .with_system(make_exclusive(3).exclusive_system().at_end())
-            .with_system(make_parallel!(1).system())
+            .with_system(make_parallel(1))
             .with_system(make_exclusive(0).exclusive_system().at_start());
         stage.run(&mut world);
         assert_eq!(
@@ -979,10 +977,10 @@ mod tests {
 
         world.get_resource_mut::<Vec<usize>>().unwrap().clear();
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(2).exclusive_system().before_commands())
+            .with_system(make_parallel(2).exclusive_system().before_commands())
-            .with_system(make_parallel!(3).exclusive_system().at_end())
+            .with_system(make_parallel(3).exclusive_system().at_end())
-            .with_system(make_parallel!(1).system())
+            .with_system(make_parallel(1))
-            .with_system(make_parallel!(0).exclusive_system().at_start());
+            .with_system(make_parallel(0).exclusive_system().at_start());
         stage.run(&mut world);
         assert_eq!(
             *world.get_resource::<Vec<usize>>().unwrap(),
@@ -1239,9 +1237,9 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(1).system().after("0").label("1"))
+            .with_system(make_parallel(1).after("0").label("1"))
-            .with_system(make_parallel!(2).system().after("1"))
+            .with_system(make_parallel(2).after("1"))
-            .with_system(make_parallel!(0).system().label("0"));
+            .with_system(make_parallel(0).label("0"));
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
         stage.run(&mut world);
@@ -1256,9 +1254,9 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(1).system().label("1").before("2"))
+            .with_system(make_parallel(1).label("1").before("2"))
-            .with_system(make_parallel!(2).system().label("2"))
+            .with_system(make_parallel(2).label("2"))
-            .with_system(make_parallel!(0).system().before("1"));
+            .with_system(make_parallel(0).before("1"));
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
         stage.run(&mut world);
@@ -1273,11 +1271,11 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(2).system().label("2"))
+            .with_system(make_parallel(2).label("2"))
-            .with_system(make_parallel!(1).system().after("0").before("2"))
+            .with_system(make_parallel(1).after("0").before("2"))
-            .with_system(make_parallel!(0).system().label("0"))
+            .with_system(make_parallel(0).label("0"))
-            .with_system(make_parallel!(4).system().label("4"))
+            .with_system(make_parallel(4).label("4"))
-            .with_system(make_parallel!(3).system().after("2").before("4"));
+            .with_system(make_parallel(3).after("2").before("4"));
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
         stage.run(&mut world);
@@ -1292,9 +1290,9 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(1).system().label("first").after("0"))
+            .with_system(make_parallel(1).label("first").after("0"))
-            .with_system(make_parallel!(2).system().after("first"))
+            .with_system(make_parallel(2).after("first"))
-            .with_system(make_parallel!(0).system().label("first").label("0"));
+            .with_system(make_parallel(0).label("first").label("0"));
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
         stage.run(&mut world);
@@ -1305,11 +1303,11 @@ mod tests {
 
         world.get_resource_mut::<Vec<usize>>().unwrap().clear();
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(2).system().after("01").label("2"))
+            .with_system(make_parallel(2).after("01").label("2"))
-            .with_system(make_parallel!(1).system().label("01").after("0"))
+            .with_system(make_parallel(1).label("01").after("0"))
-            .with_system(make_parallel!(0).system().label("01").label("0"))
+            .with_system(make_parallel(0).label("01").label("0"))
-            .with_system(make_parallel!(4).system().label("4"))
+            .with_system(make_parallel(4).label("4"))
-            .with_system(make_parallel!(3).system().after("2").before("4"));
+            .with_system(make_parallel(3).after("2").before("4"));
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
         stage.run(&mut world);
@@ -1320,17 +1318,11 @@ mod tests {
 
         world.get_resource_mut::<Vec<usize>>().unwrap().clear();
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(2).system().label("234").label("2"))
+            .with_system(make_parallel(2).label("234").label("2"))
-            .with_system(make_parallel!(1).system().before("234").after("0"))
+            .with_system(make_parallel(1).before("234").after("0"))
-            .with_system(make_parallel!(0).system().label("0"))
+            .with_system(make_parallel(0).label("0"))
-            .with_system(make_parallel!(4).system().label("234").label("4"))
+            .with_system(make_parallel(4).label("234").label("4"))
-            .with_system(
+            .with_system(make_parallel(3).label("234").after("2").before("4"));
-                make_parallel!(3)
-                    .system()
-                    .label("234")
-                    .after("2")
-                    .before("4"),
-            );
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
         stage.run(&mut world);
@@ -1346,24 +1338,22 @@ mod tests {
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
             .with_system(
-                make_parallel!(2)
+                make_parallel(2)
-                    .system()
                     .label("2")
                     .after("1")
                     .before("3")
                     .before("3"),
             )
             .with_system(
-                make_parallel!(1)
+                make_parallel(1)
-                    .system()
                     .label("1")
                     .after("0")
                     .after("0")
                     .before("2"),
             )
-            .with_system(make_parallel!(0).system().label("0").before("1"))
+            .with_system(make_parallel(0).label("0").before("1"))
-            .with_system(make_parallel!(4).system().label("4").after("3"))
+            .with_system(make_parallel(4).label("4").after("3"))
-            .with_system(make_parallel!(3).system().label("3").after("2").before("4"));
+            .with_system(make_parallel(3).label("3").after("2").before("4"));
         stage.run(&mut world);
         for container in stage.parallel.iter() {
             assert!(container.dependencies().len() <= 1);
@@ -1381,14 +1371,14 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(2).system().label("2"))
+            .with_system(make_parallel(2).label("2"))
             .with_system_set(
                 SystemSet::new()
-                    .with_system(make_parallel!(0).system().label("0"))
+                    .with_system(make_parallel(0).label("0"))
-                    .with_system(make_parallel!(4).system().label("4"))
+                    .with_system(make_parallel(4).label("4"))
-                    .with_system(make_parallel!(3).system().after("2").before("4")),
+                    .with_system(make_parallel(3).after("2").before("4")),
             )
-            .with_system(make_parallel!(1).system().after("0").before("2"));
+            .with_system(make_parallel(1).after("0").before("2"));
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
         stage.run(&mut world);
@@ -1405,12 +1395,11 @@ mod tests {
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
             .with_system(
-                make_parallel!(0)
+                make_parallel(0)
-                    .system()
                     .label("0")
                     .with_run_criteria(every_other_time),
             )
-            .with_system(make_parallel!(1).system().after("0"));
+            .with_system(make_parallel(1).after("0"));
         stage.run(&mut world);
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
@@ -1423,13 +1412,13 @@ mod tests {
 
         world.get_resource_mut::<Vec<usize>>().unwrap().clear();
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(0).system().before("1"))
+            .with_system(make_parallel(0).before("1"))
             .with_system_set(
                 SystemSet::new()
-                    .with_run_criteria(every_other_time.system())
+                    .with_run_criteria(every_other_time)
-                    .with_system(make_parallel!(1).system().label("1")),
+                    .with_system(make_parallel(1).label("1")),
             )
-            .with_system(make_parallel!(2).system().after("1"));
+            .with_system(make_parallel(2).after("1"));
         stage.run(&mut world);
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
@@ -1444,21 +1433,19 @@ mod tests {
         world.get_resource_mut::<Vec<usize>>().unwrap().clear();
         let mut stage = SystemStage::parallel()
             .with_system_run_criteria(every_other_time.label("every other time"))
-            .with_system(make_parallel!(0).system().before("1"))
+            .with_system(make_parallel(0).before("1"))
             .with_system(
-                make_parallel!(1)
+                make_parallel(1)
-                    .system()
                     .label("1")
                     .with_run_criteria("every other time"),
             )
             .with_system(
-                make_parallel!(2)
+                make_parallel(2)
-                    .system()
                     .label("2")
                     .after("1")
                     .with_run_criteria("every other time"),
             )
-            .with_system(make_parallel!(3).system().after("2"));
+            .with_system(make_parallel(3).after("2"));
         stage.run(&mut world);
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
@@ -1480,34 +1467,26 @@ mod tests {
             }
         }
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(0).system().label("0"))
+            .with_system(make_parallel(0).label("0"))
             .with_system(
-                make_parallel!(1)
+                make_parallel(1)
-                    .system()
                     .label("1")
                     .after("0")
-                    .with_run_criteria(every_other_time.system().label("every other time")),
+                    .with_run_criteria(every_other_time.label("every other time")),
             )
             .with_system(
-                make_parallel!(2)
+                make_parallel(2)
-                    .system()
                     .label("2")
                     .after("1")
                     .with_run_criteria(RunCriteria::pipe("every other time", eot_piped.system())),
             )
             .with_system(
-                make_parallel!(3)
+                make_parallel(3)
-                    .system()
                     .label("3")
                     .after("2")
                     .with_run_criteria("every other time".pipe(eot_piped.system()).label("piped")),
             )
-            .with_system(
+            .with_system(make_parallel(4).after("3").with_run_criteria("piped"));
-                make_parallel!(4)
-                    .system()
-                    .after("3")
-                    .with_run_criteria("piped"),
-            );
         for _ in 0..4 {
             stage.run(&mut world);
         }
@@ -1523,27 +1502,16 @@ mod tests {
 
         // Discarding extra criteria with matching labels.
         world.get_resource_mut::<Vec<usize>>().unwrap().clear();
-        let mut stage = SystemStage::parallel()
+        let mut stage =
-            .with_system(make_parallel!(0).system().before("1"))
+            SystemStage::parallel()
-            .with_system(
+                .with_system(make_parallel(0).before("1"))
-                make_parallel!(1).system().label("1").with_run_criteria(
+                .with_system(make_parallel(1).label("1").with_run_criteria(
-                    every_other_time
+                    every_other_time.label_discard_if_duplicate("every other time"),
-                        .system()
+                ))
-                        .label_discard_if_duplicate("every other time"),
+                .with_system(make_parallel(2).label("2").after("1").with_run_criteria(
-                ),
+                    every_other_time.label_discard_if_duplicate("every other time"),
-            )
+                ))
-            .with_system(
+                .with_system(make_parallel(3).after("2"));
-                make_parallel!(2)
-                    .system()
-                    .label("2")
-                    .after("1")
-                    .with_run_criteria(
-                        every_other_time
-                            .system()
-                            .label_discard_if_duplicate("every other time"),
-                    ),
-            )
-            .with_system(make_parallel!(3).system().after("2"));
         stage.run(&mut world);
         stage.run(&mut world);
         stage.set_executor(Box::new(SingleThreadedExecutor::default()));
@@ -1561,8 +1529,8 @@ mod tests {
     fn duplicate_run_criteria_label_panic() {
         let mut world = World::new();
         let mut stage = SystemStage::parallel()
-            .with_system_run_criteria(every_other_time.system().label("every other time"))
+            .with_system_run_criteria(every_other_time.label("every other time"))
-            .with_system_run_criteria(every_other_time.system().label("every other time"));
+            .with_system_run_criteria(every_other_time.label("every other time"));
         stage.run(&mut world);
     }
 
@@ -1571,8 +1539,7 @@ mod tests {
     fn parallel_cycle_1() {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
-        let mut stage =
+        let mut stage = SystemStage::parallel().with_system(make_parallel(0).label("0").after("0"));
-            SystemStage::parallel().with_system(make_parallel!(0).system().label("0").after("0"));
         stage.run(&mut world);
     }
 
@@ -1582,8 +1549,8 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(0).system().label("0").after("1"))
+            .with_system(make_parallel(0).label("0").after("1"))
-            .with_system(make_parallel!(1).system().label("1").after("0"));
+            .with_system(make_parallel(1).label("1").after("0"));
         stage.run(&mut world);
     }
 
@@ -1594,9 +1561,9 @@ mod tests {
 
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(make_parallel!(0).system().label("0"))
+            .with_system(make_parallel(0).label("0"))
-            .with_system(make_parallel!(1).system().after("0").before("2"))
+            .with_system(make_parallel(1).after("0").before("2"))
-            .with_system(make_parallel!(2).system().label("2").before("0"));
+            .with_system(make_parallel(2).label("2").before("0"));
         stage.run(&mut world);
     }
 
@@ -1625,21 +1592,21 @@ mod tests {
         let mut world = World::new();
 
         let mut stage = SystemStage::parallel()
-            .with_system(empty.system().label("0"))
+            .with_system(empty.label("0"))
-            .with_system(empty.system().label("1").after("0"))
+            .with_system(empty.label("1").after("0"))
-            .with_system(empty.system().label("2"))
+            .with_system(empty.label("2"))
-            .with_system(empty.system().label("3").after("2").before("4"))
+            .with_system(empty.label("3").after("2").before("4"))
-            .with_system(empty.system().label("4"));
+            .with_system(empty.label("4"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         assert_eq!(find_ambiguities(&stage.parallel).len(), 0);
 
         let mut stage = SystemStage::parallel()
-            .with_system(empty.system().label("0"))
+            .with_system(empty.label("0"))
-            .with_system(component.system().label("1").after("0"))
+            .with_system(component.label("1").after("0"))
-            .with_system(empty.system().label("2"))
+            .with_system(empty.label("2"))
-            .with_system(empty.system().label("3").after("2").before("4"))
+            .with_system(empty.label("3").after("2").before("4"))
-            .with_system(component.system().label("4"));
+            .with_system(component.label("4"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1650,11 +1617,11 @@ mod tests {
         assert_eq!(ambiguities.len(), 1);
 
         let mut stage = SystemStage::parallel()
-            .with_system(empty.system().label("0"))
+            .with_system(empty.label("0"))
-            .with_system(resource.system().label("1").after("0"))
+            .with_system(resource.label("1").after("0"))
-            .with_system(empty.system().label("2"))
+            .with_system(empty.label("2"))
-            .with_system(empty.system().label("3").after("2").before("4"))
+            .with_system(empty.label("3").after("2").before("4"))
-            .with_system(resource.system().label("4"));
+            .with_system(resource.label("4"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1665,21 +1632,21 @@ mod tests {
         assert_eq!(ambiguities.len(), 1);
 
         let mut stage = SystemStage::parallel()
-            .with_system(empty.system().label("0"))
+            .with_system(empty.label("0"))
-            .with_system(resource.system().label("1").after("0"))
+            .with_system(resource.label("1").after("0"))
-            .with_system(empty.system().label("2"))
+            .with_system(empty.label("2"))
-            .with_system(empty.system().label("3").after("2").before("4"))
+            .with_system(empty.label("3").after("2").before("4"))
-            .with_system(component.system().label("4"));
+            .with_system(component.label("4"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         assert_eq!(find_ambiguities(&stage.parallel).len(), 0);
 
         let mut stage = SystemStage::parallel()
-            .with_system(component.system().label("0"))
+            .with_system(component.label("0"))
-            .with_system(resource.system().label("1").after("0"))
+            .with_system(resource.label("1").after("0"))
-            .with_system(empty.system().label("2"))
+            .with_system(empty.label("2"))
-            .with_system(component.system().label("3").after("2").before("4"))
+            .with_system(component.label("3").after("2").before("4"))
-            .with_system(resource.system().label("4"));
+            .with_system(resource.label("4"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1694,17 +1661,11 @@ mod tests {
         assert_eq!(ambiguities.len(), 2);
 
         let mut stage = SystemStage::parallel()
-            .with_system(component.system().label("0"))
+            .with_system(component.label("0"))
-            .with_system(
+            .with_system(resource.label("1").after("0").in_ambiguity_set("a"))
-                resource
+            .with_system(empty.label("2"))
-                    .system()
+            .with_system(component.label("3").after("2").before("4"))
-                    .label("1")
+            .with_system(resource.label("4").in_ambiguity_set("a"));
-                    .after("0")
-                    .in_ambiguity_set("a"),
-            )
-            .with_system(empty.system().label("2"))
-            .with_system(component.system().label("3").after("2").before("4"))
-            .with_system(resource.system().label("4").in_ambiguity_set("a"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1715,9 +1676,9 @@ mod tests {
         assert_eq!(ambiguities.len(), 1);
 
         let mut stage = SystemStage::parallel()
-            .with_system(component.system().label("0").before("2"))
+            .with_system(component.label("0").before("2"))
-            .with_system(component.system().label("1").before("2"))
+            .with_system(component.label("1").before("2"))
-            .with_system(component.system().label("2"));
+            .with_system(component.label("2"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1728,9 +1689,9 @@ mod tests {
         assert_eq!(ambiguities.len(), 1);
 
         let mut stage = SystemStage::parallel()
-            .with_system(component.system().label("0"))
+            .with_system(component.label("0"))
-            .with_system(component.system().label("1").after("0"))
+            .with_system(component.label("1").after("0"))
-            .with_system(component.system().label("2").after("0"));
+            .with_system(component.label("2").after("0"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1741,10 +1702,10 @@ mod tests {
         assert_eq!(ambiguities.len(), 1);
 
         let mut stage = SystemStage::parallel()
-            .with_system(component.system().label("0").before("1").before("2"))
+            .with_system(component.label("0").before("1").before("2"))
-            .with_system(component.system().label("1"))
+            .with_system(component.label("1"))
-            .with_system(component.system().label("2"))
+            .with_system(component.label("2"))
-            .with_system(component.system().label("3").after("1").after("2"));
+            .with_system(component.label("3").after("1").after("2"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1755,20 +1716,20 @@ mod tests {
         assert_eq!(ambiguities.len(), 1);
 
         let mut stage = SystemStage::parallel()
-            .with_system(component.system().label("0").before("1").before("2"))
+            .with_system(component.label("0").before("1").before("2"))
-            .with_system(component.system().label("1").in_ambiguity_set("a"))
+            .with_system(component.label("1").in_ambiguity_set("a"))
-            .with_system(component.system().label("2").in_ambiguity_set("a"))
+            .with_system(component.label("2").in_ambiguity_set("a"))
-            .with_system(component.system().label("3").after("1").after("2"));
+            .with_system(component.label("3").after("1").after("2"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
         assert_eq!(ambiguities.len(), 0);
 
         let mut stage = SystemStage::parallel()
-            .with_system(component.system().label("0").before("1").before("2"))
+            .with_system(component.label("0").before("1").before("2"))
-            .with_system(component.system().label("1").in_ambiguity_set("a"))
+            .with_system(component.label("1").in_ambiguity_set("a"))
-            .with_system(component.system().label("2").in_ambiguity_set("b"))
+            .with_system(component.label("2").in_ambiguity_set("b"))
-            .with_system(component.system().label("3").after("1").after("2"));
+            .with_system(component.label("3").after("1").after("2"));
         stage.initialize_systems(&mut world);
         stage.rebuild_orders_and_dependencies();
         let ambiguities = find_ambiguities_first_labels(&stage.parallel);
@@ -1781,20 +1742,18 @@ mod tests {
         let mut stage = SystemStage::parallel()
             .with_system(
                 component
-                    .system()
                     .label("0")
                     .before("1")
                     .before("2")
                     .before("3")
                     .before("4"),
             )
-            .with_system(component.system().label("1"))
+            .with_system(component.label("1"))
-            .with_system(component.system().label("2"))
+            .with_system(component.label("2"))
-            .with_system(component.system().label("3"))
+            .with_system(component.label("3"))
-            .with_system(component.system().label("4"))
+            .with_system(component.label("4"))
             .with_system(
                 component
-                    .system()
                     .label("5")
                     .after("1")
                     .after("2")
@@ -1833,20 +1792,18 @@ mod tests {
         let mut stage = SystemStage::parallel()
             .with_system(
                 component
-                    .system()
                     .label("0")
                     .before("1")
                     .before("2")
                     .before("3")
                     .before("4"),
             )
-            .with_system(component.system().label("1").in_ambiguity_set("a"))
+            .with_system(component.label("1").in_ambiguity_set("a"))
-            .with_system(component.system().label("2").in_ambiguity_set("a"))
+            .with_system(component.label("2").in_ambiguity_set("a"))
-            .with_system(component.system().label("3").in_ambiguity_set("a"))
+            .with_system(component.label("3").in_ambiguity_set("a"))
-            .with_system(component.system().label("4").in_ambiguity_set("a"))
+            .with_system(component.label("4").in_ambiguity_set("a"))
             .with_system(
                 component
-                    .system()
                     .label("5")
                     .after("1")
                     .after("2")
@@ -1861,26 +1818,23 @@ mod tests {
         let mut stage = SystemStage::parallel()
             .with_system(
                 component
-                    .system()
                     .label("0")
                     .before("1")
                     .before("2")
                     .before("3")
                     .before("4"),
             )
-            .with_system(component.system().label("1").in_ambiguity_set("a"))
+            .with_system(component.label("1").in_ambiguity_set("a"))
-            .with_system(component.system().label("2").in_ambiguity_set("a"))
+            .with_system(component.label("2").in_ambiguity_set("a"))
             .with_system(
                 component
-                    .system()
                     .label("3")
                     .in_ambiguity_set("a")
                     .in_ambiguity_set("b"),
             )
-            .with_system(component.system().label("4").in_ambiguity_set("b"))
+            .with_system(component.label("4").in_ambiguity_set("b"))
             .with_system(
                 component
-                    .system()
                     .label("5")
                     .after("1")
                     .after("2")
@@ -2011,7 +1965,7 @@ mod tests {
 
         let mut world = World::new();
         world.insert_resource(0_usize);
-        let mut stage = SystemStage::single(query_count_system.system());
+        let mut stage = SystemStage::single(query_count_system);
 
         let entity = world.spawn().insert_bundle(()).id();
         stage.run(&mut world);
@@ -2034,7 +1988,7 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(0_usize);
         let mut stage = SystemStage::parallel();
-        stage.add_system(query_count_system.system());
+        stage.add_system(query_count_system);
 
         let entity = world.spawn().insert_bundle(()).id();
         stage.run(&mut world);
@@ -2056,7 +2010,7 @@ mod tests {
 
         let mut stage = SystemStage::parallel();
         fn work() {}
-        stage.add_system(work.system());
+        stage.add_system(work);
 
         // Overflow twice
         for _ in 0..10 {
@@ -2134,11 +2088,11 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(spawn_entity.system().label("spawn"))
+            .with_system(spawn_entity.label("spawn"))
             .with_system_set(
                 SystemSet::new()
-                    .with_run_criteria(even_number_of_entities_critiera.system())
+                    .with_run_criteria(even_number_of_entities_critiera)
-                    .with_system(count_entities.system().before("spawn")),
+                    .with_system(count_entities.before("spawn")),
             );
         stage.run(&mut world);
         stage.run(&mut world);
@@ -2169,10 +2123,10 @@ mod tests {
 
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
-        let mut stage_spawn = SystemStage::parallel().with_system(spawn_entity.system());
+        let mut stage_spawn = SystemStage::parallel().with_system(spawn_entity);
         let mut stage_count = SystemStage::parallel()
-            .with_run_criteria(even_number_of_entities_critiera.system())
+            .with_run_criteria(even_number_of_entities_critiera)
-            .with_system(count_entities.system());
+            .with_system(count_entities);
         stage_count.run(&mut world);
         stage_spawn.run(&mut world);
         stage_count.run(&mut world);

crates/bevy_ecs/src/schedule/state.rs

@@ -4,7 +4,7 @@ use crate::{
         RunCriteriaDescriptor, RunCriteriaDescriptorCoercion, RunCriteriaLabel, ShouldRun,
         SystemSet,
     },
-    system::{In, IntoChainSystem, IntoSystem, Local, Res, ResMut},
+    system::{ConfigurableSystem, In, IntoChainSystem, Local, Res, ResMut},
 };
 use std::{any::TypeId, fmt::Debug, hash::Hash};
 use thiserror::Error;
@@ -97,9 +97,8 @@ where
         (|state: Res<State<T>>, pred: Local<Option<T>>| {
             state.stack.last().unwrap() == pred.as_ref().unwrap() && state.transition.is_none()
         })
-        .system()
         .config(|(_, pred)| *pred = Some(Some(s.clone())))
-        .chain(should_run_adapter::<T>.system())
+        .chain(should_run_adapter::<T>)
         .after(DriverLabel::of::<T>())
         .label_discard_if_duplicate(StateCallback::Update.into_label(s))
     }
@@ -118,9 +117,8 @@ where
             Some(_) => false,
             None => *is_inactive,
         })
-        .system()
         .config(|(_, _, pred)| *pred = Some(Some(s.clone())))
-        .chain(should_run_adapter::<T>.system())
+        .chain(should_run_adapter::<T>)
         .after(DriverLabel::of::<T>())
         .label_discard_if_duplicate(StateCallback::InactiveUpdate.into_label(s))
     }
@@ -151,9 +149,8 @@ where
             Some(_) => false,
             None => *is_in_stack,
         })
-        .system()
         .config(|(_, _, pred)| *pred = Some(Some(s.clone())))
-        .chain(should_run_adapter::<T>.system())
+        .chain(should_run_adapter::<T>)
         .after(DriverLabel::of::<T>())
         .label_discard_if_duplicate(StateCallback::InStackUpdate.into_label(s))
     }
@@ -171,9 +168,8 @@ where
                     _ => false,
                 })
         })
-        .system()
         .config(|(_, pred)| *pred = Some(Some(s.clone())))
-        .chain(should_run_adapter::<T>.system())
+        .chain(should_run_adapter::<T>)
         .after(DriverLabel::of::<T>())
         .label_discard_if_duplicate(StateCallback::Enter.into_label(s))
     }
@@ -189,9 +185,8 @@ where
                     _ => false,
                 })
         })
-        .system()
         .config(|(_, pred)| *pred = Some(Some(s.clone())))
-        .chain(should_run_adapter::<T>.system())
+        .chain(should_run_adapter::<T>)
         .after(DriverLabel::of::<T>())
         .label_discard_if_duplicate(StateCallback::Exit.into_label(s))
     }
@@ -206,9 +201,8 @@ where
                     _ => false,
                 })
         })
-        .system()
         .config(|(_, pred)| *pred = Some(Some(s.clone())))
-        .chain(should_run_adapter::<T>.system())
+        .chain(should_run_adapter::<T>)
         .after(DriverLabel::of::<T>())
         .label_discard_if_duplicate(StateCallback::Pause.into_label(s))
     }
@@ -223,9 +217,8 @@ where
                     _ => false,
                 })
         })
-        .system()
         .config(|(_, pred)| *pred = Some(Some(s.clone())))
-        .chain(should_run_adapter::<T>.system())
+        .chain(should_run_adapter::<T>)
         .after(DriverLabel::of::<T>())
         .label_discard_if_duplicate(StateCallback::Resume.into_label(s))
     }
@@ -259,8 +252,7 @@ where
     /// Important note: this set must be inserted **before** all other state-dependant sets to work
     /// properly!
     pub fn get_driver() -> SystemSet {
-        SystemSet::default()
+        SystemSet::default().with_run_criteria(state_cleaner::<T>.label(DriverLabel::of::<T>()))
-            .with_run_criteria(state_cleaner::<T>.system().label(DriverLabel::of::<T>()))
     }
 
     pub fn new(initial: T) -> Self {
@@ -516,81 +508,63 @@ mod test {
         stage
             .add_system_set(
                 State::on_enter_set(MyState::S1)
-                    .with_system((|mut r: ResMut<Vec<&'static str>>| r.push("startup")).system()),
+                    .with_system(|mut r: ResMut<Vec<&'static str>>| r.push("startup")),
-            )
-            .add_system_set(
-                State::on_update_set(MyState::S1).with_system(
-                    (|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
-                        r.push("update S1");
-                        s.overwrite_replace(MyState::S2).unwrap();
-                    })
-                    .system(),
-                ),
             )
+            .add_system_set(State::on_update_set(MyState::S1).with_system(
+                |mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
+                    r.push("update S1");
+                    s.overwrite_replace(MyState::S2).unwrap();
+                },
+            ))
             .add_system_set(
                 State::on_enter_set(MyState::S2)
-                    .with_system((|mut r: ResMut<Vec<&'static str>>| r.push("enter S2")).system()),
+                    .with_system(|mut r: ResMut<Vec<&'static str>>| r.push("enter S2")),
-            )
-            .add_system_set(
-                State::on_update_set(MyState::S2).with_system(
-                    (|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
-                        r.push("update S2");
-                        s.overwrite_replace(MyState::S3).unwrap();
-                    })
-                    .system(),
-                ),
             )
+            .add_system_set(State::on_update_set(MyState::S2).with_system(
+                |mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
+                    r.push("update S2");
+                    s.overwrite_replace(MyState::S3).unwrap();
+                },
+            ))
             .add_system_set(
                 State::on_exit_set(MyState::S2)
-                    .with_system((|mut r: ResMut<Vec<&'static str>>| r.push("exit S2")).system()),
+                    .with_system(|mut r: ResMut<Vec<&'static str>>| r.push("exit S2")),
             )
             .add_system_set(
                 State::on_enter_set(MyState::S3)
-                    .with_system((|mut r: ResMut<Vec<&'static str>>| r.push("enter S3")).system()),
+                    .with_system(|mut r: ResMut<Vec<&'static str>>| r.push("enter S3")),
-            )
-            .add_system_set(
-                State::on_update_set(MyState::S3).with_system(
-                    (|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
-                        r.push("update S3");
-                        s.overwrite_push(MyState::S4).unwrap();
-                    })
-                    .system(),
-                ),
             )
+            .add_system_set(State::on_update_set(MyState::S3).with_system(
+                |mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
+                    r.push("update S3");
+                    s.overwrite_push(MyState::S4).unwrap();
+                },
+            ))
             .add_system_set(
                 State::on_pause_set(MyState::S3)
-                    .with_system((|mut r: ResMut<Vec<&'static str>>| r.push("pause S3")).system()),
+                    .with_system(|mut r: ResMut<Vec<&'static str>>| r.push("pause S3")),
-            )
-            .add_system_set(
-                State::on_update_set(MyState::S4).with_system(
-                    (|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
-                        r.push("update S4");
-                        s.overwrite_push(MyState::S5).unwrap();
-                    })
-                    .system(),
-                ),
-            )
-            .add_system_set(
-                State::on_inactive_update_set(MyState::S4).with_system(
-                    (|mut r: ResMut<Vec<&'static str>>| r.push("inactive S4"))
-                        .system()
-                        .label("inactive s4"),
-                ),
             )
+            .add_system_set(State::on_update_set(MyState::S4).with_system(
+                |mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
+                    r.push("update S4");
+                    s.overwrite_push(MyState::S5).unwrap();
+                },
+            ))
+            .add_system_set(State::on_inactive_update_set(MyState::S4).with_system(
+                (|mut r: ResMut<Vec<&'static str>>| r.push("inactive S4")).label("inactive s4"),
+            ))
             .add_system_set(
                 State::on_update_set(MyState::S5).with_system(
                     (|mut r: ResMut<Vec<&'static str>>, mut s: ResMut<State<MyState>>| {
                         r.push("update S5");
                         s.overwrite_push(MyState::S6).unwrap();
                     })
-                    .system()
                     .after("inactive s4"),
                 ),
             )
             .add_system_set(
                 State::on_inactive_update_set(MyState::S5).with_system(
                     (|mut r: ResMut<Vec<&'static str>>| r.push("inactive S5"))
-                        .system()
                         .label("inactive s5")
                         .after("inactive s4"),
                 ),
@@ -601,17 +575,16 @@ mod test {
                         r.push("update S6");
                         s.overwrite_push(MyState::Final).unwrap();
                     })
-                    .system()
                     .after("inactive s5"),
                 ),
             )
             .add_system_set(
                 State::on_resume_set(MyState::S4)
-                    .with_system((|mut r: ResMut<Vec<&'static str>>| r.push("resume S4")).system()),
+                    .with_system(|mut r: ResMut<Vec<&'static str>>| r.push("resume S4")),
             )
             .add_system_set(
                 State::on_exit_set(MyState::S5)
-                    .with_system((|mut r: ResMut<Vec<&'static str>>| r.push("exit S4")).system()),
+                    .with_system(|mut r: ResMut<Vec<&'static str>>| r.push("exit S4")),
             );
 
         const EXPECTED: &[&str] = &[
@@ -671,7 +644,7 @@ mod test {
         world.insert_resource(State::new(AppState::Main));
         world.insert_resource(false);
         world.insert_resource("control");
-        let mut stage = SystemStage::parallel().with_system(should_run_once.system());
+        let mut stage = SystemStage::parallel().with_system(should_run_once);
         stage.run(&mut world);
         assert!(*world.get_resource::<bool>().unwrap(), "after control");
 
@@ -679,7 +652,7 @@ mod test {
         world.insert_resource("test");
         let mut stage = SystemStage::parallel()
             .with_system_set(State::<AppState>::get_driver())
-            .with_system(should_run_once.system());
+            .with_system(should_run_once);
         stage.run(&mut world);
         assert!(*world.get_resource::<bool>().unwrap(), "after test");
     }

crates/bevy_ecs/src/schedule/system_container.rs

@@ -36,7 +36,7 @@ pub(super) struct ExclusiveSystemContainer {
 }
 
 impl ExclusiveSystemContainer {
-    pub fn from_descriptor(descriptor: ExclusiveSystemDescriptor) -> Self {
+    pub(super) fn from_descriptor(descriptor: ExclusiveSystemDescriptor) -> Self {
         ExclusiveSystemContainer {
             system: descriptor.system,
             run_criteria_index: None,
@@ -49,7 +49,7 @@ impl ExclusiveSystemContainer {
         }
     }
 
-    pub fn system_mut(&mut self) -> &mut Box<dyn ExclusiveSystem> {
+    pub(super) fn system_mut(&mut self) -> &mut Box<dyn ExclusiveSystem> {
         &mut self.system
     }
 }

crates/bevy_ecs/src/schedule/system_descriptor.rs

@@ -30,8 +30,8 @@ use crate::{
 /// struct Something;
 ///
 /// SystemStage::parallel()
-///     .with_system(do_something.system().label(Something))
+///     .with_system(do_something.label(Something))
-///     .with_system(do_the_other_thing.system().after(Something))
+///     .with_system(do_the_other_thing.after(Something))
 ///     .with_system(do_something_else.exclusive_system().at_end());
 /// ```
 pub enum SystemDescriptor {
@@ -60,6 +60,12 @@ where
     }
 }
 
+impl IntoSystemDescriptor<()> for SystemDescriptor {
+    fn into_descriptor(self) -> SystemDescriptor {
+        self
+    }
+}
+
 impl IntoSystemDescriptor<()> for BoxedSystem<(), ()> {
     fn into_descriptor(self) -> SystemDescriptor {
         new_parallel_descriptor(self).into_descriptor()

crates/bevy_ecs/src/storage/blob_vec.rs

@@ -267,9 +267,13 @@ const fn padding_needed_for(layout: &Layout, align: usize) -> usize {
 #[cfg(test)]
 mod tests {
     use super::BlobVec;
-    use crate::component::TypeInfo;
     use std::{alloc::Layout, cell::RefCell, rc::Rc};
 
+    // SAFETY: The pointer points to a valid value of type `T` and it is safe to drop this value.
+    unsafe fn drop_ptr<T>(x: *mut u8) {
+        x.cast::<T>().drop_in_place()
+    }
+
     /// # Safety
     ///
     /// `blob_vec` must have a layout that matches Layout::new::<T>()
@@ -300,7 +304,7 @@ mod tests {
     #[test]
     fn resize_test() {
         let item_layout = Layout::new::<usize>();
-        let drop = TypeInfo::drop_ptr::<usize>;
+        let drop = drop_ptr::<usize>;
         let mut blob_vec = BlobVec::new(item_layout, drop, 64);
         unsafe {
             for i in 0..1_000 {
@@ -330,7 +334,7 @@ mod tests {
         let drop_counter = Rc::new(RefCell::new(0));
         {
             let item_layout = Layout::new::<Foo>();
-            let drop = TypeInfo::drop_ptr::<Foo>;
+            let drop = drop_ptr::<Foo>;
             let mut blob_vec = BlobVec::new(item_layout, drop, 2);
             assert_eq!(blob_vec.capacity(), 2);
             unsafe {
@@ -390,7 +394,7 @@ mod tests {
     #[test]
     fn blob_vec_drop_empty_capacity() {
         let item_layout = Layout::new::<Foo>();
-        let drop = TypeInfo::drop_ptr::<Foo>;
+        let drop = drop_ptr::<Foo>;
         let _ = BlobVec::new(item_layout, drop, 0);
     }
 }

crates/bevy_ecs/src/storage/table.rs

@@ -522,17 +522,12 @@ impl IndexMut<TableId> for Tables {
 
 #[cfg(test)]
 mod tests {
-    use crate::{
+    use crate::{component::Components, entity::Entity, storage::Table};
-        component::{Components, TypeInfo},
-        entity::Entity,
-        storage::Table,
-    };
 
     #[test]
     fn table() {
         let mut components = Components::default();
-        let type_info = TypeInfo::of::<usize>();
+        let component_id = components.get_or_insert_id::<usize>();
-        let component_id = components.get_or_insert_with(type_info.type_id(), || type_info);
         let columns = &[component_id];
         let mut table = Table::with_capacity(0, columns.len());
         table.add_column(components.get_info(component_id).unwrap());

crates/bevy_ecs/src/system/commands/mod.rs

@@ -6,7 +6,7 @@ use crate::{
     entity::{Entities, Entity},
     world::World,
 };
-use bevy_utils::tracing::debug;
+use bevy_utils::tracing::{error, warn};
 pub use command_queue::CommandQueue;
 use std::marker::PhantomData;
 
@@ -16,12 +16,12 @@ pub trait Command: Send + Sync + 'static {
 }
 
 /// A list of commands that will be run to modify a [`World`].
-pub struct Commands<'s, 'w> {
+pub struct Commands<'w, 's> {
     queue: &'s mut CommandQueue,
     entities: &'w Entities,
 }
 
-impl<'s, 'w> Commands<'s, 'w> {
+impl<'w, 's> Commands<'w, 's> {
     /// Create a new `Commands` from a queue and a world.
     pub fn new(queue: &'s mut CommandQueue, world: &'w World) -> Self {
         Self {
@@ -50,7 +50,7 @@ impl<'s, 'w> Commands<'s, 'w> {
     /// }
     /// # example_system.system();
     /// ```
-    pub fn spawn(&mut self) -> EntityCommands<'s, 'w, '_> {
+    pub fn spawn<'a>(&'a mut self) -> EntityCommands<'w, 's, 'a> {
         let entity = self.entities.reserve_entity();
         EntityCommands {
             entity,
@@ -58,7 +58,14 @@ impl<'s, 'w> Commands<'s, 'w> {
         }
     }
 
-    pub fn get_or_spawn(&mut self, entity: Entity) -> EntityCommands<'s, 'w, '_> {
+    /// Returns an [EntityCommands] for the given `entity` (if it exists) or spawns one if it doesn't exist.
+    /// This will return [None] if the `entity` exists with a different generation.
+    ///
+    /// # Note
+    /// Spawning a specific `entity` value is rarely the right choice. Most apps should favor [`Commands::spawn`].
+    /// This method should generally only be used for sharing entities across apps, and only when they have a
+    /// scheme worked out to share an ID space (which doesn't happen by default).
+    pub fn get_or_spawn<'a>(&'a mut self, entity: Entity) -> EntityCommands<'w, 's, 'a> {
         self.add(GetOrSpawn { entity });
         EntityCommands {
             entity,
@@ -66,9 +73,8 @@ impl<'s, 'w> Commands<'s, 'w> {
         }
     }
 
-    // TODO: this is a hack to work around the "multiple worlds" limitations:
+    /// Spawns a [Bundle] without pre-allocating an [Entity]. The [Entity] will be allocated when
-    // Right now Commands must allocate entities from their "scheduled" world, but Commands might be applied to other worlds,
+    /// this [Command] is applied.
-    // such as the "render world"
     pub fn spawn_and_forget(&mut self, bundle: impl Bundle) {
         self.queue.push(Spawn { bundle })
     }
@@ -113,7 +119,7 @@ impl<'s, 'w> Commands<'s, 'w> {
     /// }
     /// # example_system.system();
     /// ```
-    pub fn spawn_bundle<T: Bundle>(&mut self, bundle: T) -> EntityCommands<'s, 'w, '_> {
+    pub fn spawn_bundle<'a, T: Bundle>(&'a mut self, bundle: T) -> EntityCommands<'w, 's, 'a> {
         let mut e = self.spawn();
         e.insert_bundle(bundle);
         e
@@ -138,7 +144,13 @@ impl<'s, 'w> Commands<'s, 'w> {
     /// }
     /// # example_system.system();
     /// ```
-    pub fn entity(&mut self, entity: Entity) -> EntityCommands<'s, 'w, '_> {
+    #[track_caller]
+    pub fn entity<'a>(&'a mut self, entity: Entity) -> EntityCommands<'w, 's, 'a> {
+        assert!(
+            self.entities.contains(entity),
+            "Attempting to create an EntityCommands for entity {:?}, which doesn't exist.",
+            entity
+        );
         EntityCommands {
             entity,
             commands: self,
@@ -155,6 +167,23 @@ impl<'s, 'w> Commands<'s, 'w> {
         self.queue.push(SpawnBatch { bundles_iter });
     }
 
+    /// For a given batch of ([Entity], [Bundle]) pairs, either spawns each [Entity] with the given
+    /// bundle (if the entity does not exist), or inserts the [Bundle] (if the entity already exists).
+    /// This is faster than doing equivalent operations one-by-one.
+    ///
+    /// # Note
+    /// Spawning a specific `entity` value is rarely the right choice. Most apps should use [`Commands::spawn_batch`].
+    /// This method should generally only be used for sharing entities across apps, and only when they have a scheme
+    /// worked out to share an ID space (which doesn't happen by default).
+    pub fn insert_or_spawn_batch<I, B>(&mut self, bundles_iter: I)
+    where
+        I: IntoIterator + Send + Sync + 'static,
+        I::IntoIter: Iterator<Item = (Entity, B)>,
+        B: Bundle,
+    {
+        self.queue.push(InsertOrSpawnBatch { bundles_iter });
+    }
+
     /// See [`World::insert_resource`].
     pub fn insert_resource<T: Component>(&mut self, resource: T) {
         self.queue.push(InsertResource { resource })
@@ -174,12 +203,12 @@ impl<'s, 'w> Commands<'s, 'w> {
 }
 
 /// A list of commands that will be run to modify an [`Entity`].
-pub struct EntityCommands<'s, 'w, 'a> {
+pub struct EntityCommands<'w, 's, 'a> {
     entity: Entity,
-    commands: &'a mut Commands<'s, 'w>,
+    commands: &'a mut Commands<'w, 's>,
 }
 
-impl<'s, 'w, 'a> EntityCommands<'s, 'w, 'a> {
+impl<'w, 's, 'a> EntityCommands<'w, 's, 'a> {
     /// Retrieves the current entity's unique [`Entity`] id.
     #[inline]
     pub fn id(&self) -> Entity {
@@ -267,7 +296,7 @@ impl<'s, 'w, 'a> EntityCommands<'s, 'w, 'a> {
     }
 
     /// Returns the underlying `[Commands]`.
-    pub fn commands(&mut self) -> &mut Commands<'s, 'w> {
+    pub fn commands(&mut self) -> &mut Commands<'w, 's> {
         self.commands
     }
 }
@@ -314,6 +343,32 @@ where
     }
 }
 
+pub struct InsertOrSpawnBatch<I, B>
+where
+    I: IntoIterator + Send + Sync + 'static,
+    B: Bundle,
+    I::IntoIter: Iterator<Item = (Entity, B)>,
+{
+    pub bundles_iter: I,
+}
+
+impl<I, B> Command for InsertOrSpawnBatch<I, B>
+where
+    I: IntoIterator + Send + Sync + 'static,
+    B: Bundle,
+    I::IntoIter: Iterator<Item = (Entity, B)>,
+{
+    fn write(self, world: &mut World) {
+        if let Err(invalid_entities) = world.insert_or_spawn_batch(self.bundles_iter) {
+            error!(
+                "Failed to 'insert or spawn' bundle of type {} into the following invalid entities: {:?}",
+                std::any::type_name::<B>(),
+                invalid_entities
+            );
+        }
+    }
+}
+
 #[derive(Debug)]
 pub struct Despawn {
     pub entity: Entity,
@@ -322,7 +377,9 @@ pub struct Despawn {
 impl Command for Despawn {
     fn write(self, world: &mut World) {
         if !world.despawn(self.entity) {
-            debug!("Failed to despawn non-existent entity {:?}", self.entity);
+            warn!("Could not despawn entity {:?} because it doesn't exist in this World.\n\
+                    If this command was added to a newly spawned entity, ensure that you have not despawned that entity within the same stage.\n\
+                    This may have occurred due to system order ambiguity, or if the spawning system has multiple command buffers", self.entity);
         }
     }
 }
@@ -337,7 +394,13 @@ where
     T: Bundle + 'static,
 {
     fn write(self, world: &mut World) {
-        world.entity_mut(self.entity).insert_bundle(self.bundle);
+        if let Some(mut entity) = world.get_entity_mut(self.entity) {
+            entity.insert_bundle(self.bundle);
+        } else {
+            panic!("Could not insert a bundle (of type `{}`) for entity {:?} because it doesn't exist in this World.\n\
+                    If this command was added to a newly spawned entity, ensure that you have not despawned that entity within the same stage.\n\
+                    This may have occurred due to system order ambiguity, or if the spawning system has multiple command buffers", std::any::type_name::<T>(), self.entity);
+        }
     }
 }
 
@@ -352,7 +415,13 @@ where
     T: Component,
 {
     fn write(self, world: &mut World) {
-        world.entity_mut(self.entity).insert(self.component);
+        if let Some(mut entity) = world.get_entity_mut(self.entity) {
+            entity.insert(self.component);
+        } else {
+            panic!("Could not add a component (of type `{}`) to entity {:?} because it doesn't exist in this World.\n\
+                    If this command was added to a newly spawned entity, ensure that you have not despawned that entity within the same stage.\n\
+                    This may have occurred due to system order ambiguity, or if the spawning system has multiple command buffers", std::any::type_name::<T>(), self.entity);
+        }
     }
 }
 

crates/bevy_ecs/src/system/exclusive_system.rs

@@ -96,6 +96,7 @@ impl ExclusiveSystem for ExclusiveSystemCoerced {
         for archetype in archetypes.archetypes[archetype_index_range].iter() {
             self.system.new_archetype(archetype);
         }
+
         self.system.run((), world);
         self.system.apply_buffers(world);
     }
@@ -127,7 +128,7 @@ mod tests {
         entity::Entity,
         query::With,
         schedule::{Stage, SystemStage},
-        system::{Commands, IntoExclusiveSystem, IntoSystem, Query, ResMut},
+        system::{Commands, IntoExclusiveSystem, Query, ResMut},
         world::World,
     };
     #[test]
@@ -145,7 +146,7 @@ mod tests {
             }
         }
 
-        let mut stage = SystemStage::parallel().with_system(removal.system());
+        let mut stage = SystemStage::parallel().with_system(removal);
         world.spawn().insert(0.0f32);
         world.insert_resource(0usize);
         stage.run(&mut world);
@@ -175,7 +176,7 @@ mod tests {
         let mut world = World::new();
         world.insert_resource(Vec::<usize>::new());
         let mut stage = SystemStage::parallel()
-            .with_system(spawn_entity.system())
+            .with_system(spawn_entity)
             .with_system(count_entities.exclusive_system());
         stage.run(&mut world);
         stage.run(&mut world);

crates/bevy_ecs/src/system/function_system.rs

@@ -24,7 +24,7 @@ pub struct SystemMeta {
 }
 
 impl SystemMeta {
-    pub fn new<T>() -> Self {
+    fn new<T>() -> Self {
         Self {
             name: std::any::type_name::<T>().into(),
             archetype_component_access: Access::default(),
@@ -87,10 +87,10 @@ impl<Param: SystemParam> SystemState<Param> {
 
     /// Retrieve the [`SystemParam`] values. This can only be called when all parameters are read-only.
     #[inline]
-    pub fn get<'s, 'w>(
+    pub fn get<'w, 's>(
         &'s mut self,
         world: &'w World,
-    ) -> <Param::Fetch as SystemParamFetch<'s, 'w>>::Item
+    ) -> <Param::Fetch as SystemParamFetch<'w, 's>>::Item
     where
         Param::Fetch: ReadOnlySystemParamFetch,
     {
@@ -101,10 +101,10 @@ impl<Param: SystemParam> SystemState<Param> {
 
     /// Retrieve the mutable [`SystemParam`] values.
     #[inline]
-    pub fn get_mut<'s, 'w>(
+    pub fn get_mut<'w, 's>(
         &'s mut self,
         world: &'w mut World,
-    ) -> <Param::Fetch as SystemParamFetch<'s, 'w>>::Item {
+    ) -> <Param::Fetch as SystemParamFetch<'w, 's>>::Item {
         self.validate_world_and_update_archetypes(world);
         // SAFE: World is uniquely borrowed and matches the World this SystemState was created with.
         unsafe { self.get_unchecked_manual(world) }
@@ -145,10 +145,10 @@ impl<Param: SystemParam> SystemState<Param> {
     /// access is safe in the context of global [`World`] access. The passed-in [`World`] _must_ be the [`World`] the [`SystemState`] was
     /// created with.   
     #[inline]
-    pub unsafe fn get_unchecked_manual<'s, 'w>(
+    pub unsafe fn get_unchecked_manual<'w, 's>(
         &'s mut self,
         world: &'w World,
-    ) -> <Param::Fetch as SystemParamFetch<'s, 'w>>::Item {
+    ) -> <Param::Fetch as SystemParamFetch<'w, 's>>::Item {
         let change_tick = world.increment_change_tick();
         let param = <Param::Fetch as SystemParamFetch>::get_param(
             &mut self.param_state,
@@ -228,7 +228,7 @@ pub struct InputMarker;
 ///
 /// You get this by calling [`IntoSystem::system`]  on a function that only accepts
 /// [`SystemParam`]s. The output of the system becomes the functions return type, while the input
-/// becomes the functions [`In`] tagged parameter or `()` if no such paramater exists.
+/// becomes the functions [`In`] tagged parameter or `()` if no such parameter exists.
 pub struct FunctionSystem<In, Out, Param, Marker, F>
 where
     Param: SystemParam,
@@ -254,7 +254,7 @@ impl<In, Out, Param: SystemParam, Marker, F> FunctionSystem<In, Out, Param, Mark
     /// fn local_is_42(local: Local<usize>) {
     ///     assert_eq!(*local, 42);
     /// }
-    /// let mut system = local_is_42.system().config(|config| config.0 = Some(42));
+    /// let mut system = local_is_42.config(|config| config.0 = Some(42));
     /// system.initialize(world);
     /// system.run((), world);
     /// ```

crates/bevy_ecs/src/system/mod.rs

@@ -24,11 +24,11 @@ mod tests {
         bundle::Bundles,
         component::Components,
         entity::{Entities, Entity},
-        query::{Added, Changed, Or, With, Without},
+        query::{Added, Changed, Or, QueryState, With, Without},
         schedule::{Schedule, Stage, SystemStage},
         system::{
-            ConfigurableSystem, IntoExclusiveSystem, IntoSystem, Local, Query, QuerySet,
+            ConfigurableSystem, IntoExclusiveSystem, IntoSystem, Local, NonSend, NonSendMut, Query,
-            RemovedComponents, Res, ResMut, System, SystemState,
+            QuerySet, RemovedComponents, Res, ResMut, System, SystemState,
         },
         world::{FromWorld, World},
     };
@@ -60,7 +60,7 @@ mod tests {
         system.run((), &mut world);
     }
 
-    fn run_system<S: System<In = (), Out = ()>>(world: &mut World, system: S) {
+    fn run_system<Param, S: IntoSystem<(), (), Param>>(world: &mut World, system: S) {
         let mut schedule = Schedule::default();
         let mut update = SystemStage::parallel();
         update.add_system(system);
@@ -121,7 +121,7 @@ mod tests {
         world.spawn().insert_bundle((A, C));
         world.spawn().insert_bundle((A, D));
 
-        run_system(&mut world, query_system.system());
+        run_system(&mut world, query_system);
 
         assert!(*world.get_resource::<bool>().unwrap(), "system ran");
     }
@@ -131,9 +131,9 @@ mod tests {
         // Regression test for issue #762
         fn query_system(
             mut ran: ResMut<bool>,
-            set: QuerySet<(
+            mut set: QuerySet<(
-                Query<(), Or<(Changed<A>, Changed<B>)>>,
+                QueryState<(), Or<(Changed<A>, Changed<B>)>>,
-                Query<(), Or<(Added<A>, Added<B>)>>,
+                QueryState<(), Or<(Added<A>, Added<B>)>>,
             )>,
         ) {
             let changed = set.q0().iter().count();
@@ -149,7 +149,7 @@ mod tests {
         world.insert_resource(false);
         world.spawn().insert_bundle((A, B));
 
-        run_system(&mut world, query_system.system());
+        run_system(&mut world, query_system);
 
         assert!(*world.get_resource::<bool>().unwrap(), "system ran");
     }
@@ -179,7 +179,7 @@ mod tests {
 
         let mut schedule = Schedule::default();
         let mut update = SystemStage::parallel();
-        update.add_system(incr_e_on_flip.system());
+        update.add_system(incr_e_on_flip);
         schedule.add_stage("update", update);
         schedule.add_stage(
             "clear_trackers",
@@ -206,7 +206,7 @@ mod tests {
         fn sys(_q1: Query<&mut A>, _q2: Query<&mut A>) {}
 
         let mut world = World::default();
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[test]
@@ -214,7 +214,7 @@ mod tests {
         fn sys(_q1: Query<&mut A, With<B>>, _q2: Query<&mut A, Without<B>>) {}
 
         let mut world = World::default();
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[test]
@@ -222,7 +222,7 @@ mod tests {
         fn sys(_q1: Query<(&mut A, &B)>, _q2: Query<&mut A, Without<B>>) {}
 
         let mut world = World::default();
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[test]
@@ -231,32 +231,36 @@ mod tests {
         fn sys(_q1: Query<&A>, _q2: Query<&mut A>) {}
 
         let mut world = World::default();
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[test]
     fn query_set_system() {
-        fn sys(mut _set: QuerySet<(Query<&mut A>, Query<&A>)>) {}
+        fn sys(mut _set: QuerySet<(QueryState<&mut A>, QueryState<&A>)>) {}
         let mut world = World::default();
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[test]
     #[should_panic]
     fn conflicting_query_with_query_set_system() {
-        fn sys(_query: Query<&mut A>, _set: QuerySet<(Query<&mut A>, Query<&B>)>) {}
+        fn sys(_query: Query<&mut A>, _set: QuerySet<(QueryState<&mut A>, QueryState<&B>)>) {}
 
         let mut world = World::default();
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[test]
     #[should_panic]
     fn conflicting_query_sets_system() {
-        fn sys(_set_1: QuerySet<(Query<&mut A>,)>, _set_2: QuerySet<(Query<&mut A>, Query<&B>)>) {}
+        fn sys(
+            _set_1: QuerySet<(QueryState<&mut A>,)>,
+            _set_2: QuerySet<(QueryState<&mut A>, QueryState<&B>)>,
+        ) {
+        }
 
         let mut world = World::default();
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[derive(Default)]
@@ -264,39 +268,39 @@ mod tests {
         _buffer: Vec<u8>,
     }
 
-    fn test_for_conflicting_resources<S: System<In = (), Out = ()>>(sys: S) {
+    fn test_for_conflicting_resources<Param, S: IntoSystem<(), (), Param>>(sys: S) {
         let mut world = World::default();
         world.insert_resource(BufferRes::default());
         world.insert_resource(A);
         world.insert_resource(B);
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
     }
 
     #[test]
     #[should_panic]
     fn conflicting_system_resources() {
         fn sys(_: ResMut<BufferRes>, _: Res<BufferRes>) {}
-        test_for_conflicting_resources(sys.system())
+        test_for_conflicting_resources(sys)
     }
 
     #[test]
     #[should_panic]
     fn conflicting_system_resources_reverse_order() {
         fn sys(_: Res<BufferRes>, _: ResMut<BufferRes>) {}
-        test_for_conflicting_resources(sys.system())
+        test_for_conflicting_resources(sys)
     }
 
     #[test]
     #[should_panic]
     fn conflicting_system_resources_multiple_mutable() {
         fn sys(_: ResMut<BufferRes>, _: ResMut<BufferRes>) {}
-        test_for_conflicting_resources(sys.system())
+        test_for_conflicting_resources(sys)
     }
 
     #[test]
     fn nonconflicting_system_resources() {
         fn sys(_: Local<BufferRes>, _: ResMut<BufferRes>, _: Local<A>, _: ResMut<A>) {}
-        test_for_conflicting_resources(sys.system())
+        test_for_conflicting_resources(sys)
     }
 
     #[test]
@@ -321,12 +325,54 @@ mod tests {
             *modified = true;
         }
 
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
 
         // ensure the system actually ran
         assert!(*world.get_resource::<bool>().unwrap());
     }
 
+    #[test]
+    fn non_send_option_system() {
+        let mut world = World::default();
+
+        world.insert_resource(false);
+        struct NotSend1(std::rc::Rc<i32>);
+        struct NotSend2(std::rc::Rc<i32>);
+        world.insert_non_send(NotSend1(std::rc::Rc::new(0)));
+
+        fn sys(
+            op: Option<NonSend<NotSend1>>,
+            mut _op2: Option<NonSendMut<NotSend2>>,
+            mut run: ResMut<bool>,
+        ) {
+            op.expect("NonSend should exist");
+            *run = true;
+        }
+
+        run_system(&mut world, sys);
+        // ensure the system actually ran
+        assert!(*world.get_resource::<bool>().unwrap());
+    }
+
+    #[test]
+    fn non_send_system() {
+        let mut world = World::default();
+
+        world.insert_resource(false);
+        struct NotSend1(std::rc::Rc<i32>);
+        struct NotSend2(std::rc::Rc<i32>);
+
+        world.insert_non_send(NotSend1(std::rc::Rc::new(1)));
+        world.insert_non_send(NotSend2(std::rc::Rc::new(2)));
+
+        fn sys(_op: NonSend<NotSend1>, mut _op2: NonSendMut<NotSend2>, mut run: ResMut<bool>) {
+            *run = true;
+        }
+
+        run_system(&mut world, sys);
+        assert!(*world.get_resource::<bool>().unwrap());
+    }
+
     #[test]
     fn remove_tracking() {
         let mut world = World::new();
@@ -352,7 +398,7 @@ mod tests {
             *ran = true;
         }
 
-        run_system(&mut world, validate_removed.system());
+        run_system(&mut world, validate_removed);
         assert!(*world.get_resource::<bool>().unwrap(), "system ran");
     }
 
@@ -365,18 +411,10 @@ mod tests {
             *modified = true;
         }
 
-        run_system(
+        run_system(&mut world, sys.config(|config| config.0 = Some(42)));
-            &mut world,
-            sys.system().config(|config| config.0 = Some(42)),
-        );
 
         // ensure the system actually ran
         assert!(*world.get_resource::<bool>().unwrap());
-
-        // Now do the same with omitted `.system()`.
-        world.insert_resource(false);
-        run_system(&mut world, sys.config(|config| config.0 = Some(42)));
-        assert!(*world.get_resource::<bool>().unwrap());
     }
 
     #[test]
@@ -417,7 +455,7 @@ mod tests {
             *modified = true;
         }
 
-        run_system(&mut world, sys.system());
+        run_system(&mut world, sys);
 
         // ensure the system actually ran
         assert!(*world.get_resource::<bool>().unwrap());
@@ -528,12 +566,15 @@ mod tests {
         world.insert_resource(A(42));
         world.spawn().insert(B(7));
 
-        let mut system_state: SystemState<(Res<A>, Query<&B>, QuerySet<(Query<&C>, Query<&D>)>)> =
+        let mut system_state: SystemState<(
-            SystemState::new(&mut world);
+            Res<A>,
+            Query<&B>,
+            QuerySet<(QueryState<&C>, QueryState<&D>)>,
+        )> = SystemState::new(&mut world);
         let (a, query, _) = system_state.get(&world);
         assert_eq!(*a, A(42), "returned resource matches initial value");
         assert_eq!(
-            *query.single().unwrap(),
+            *query.single(),
             B(7),
             "returned component matches initial value"
         );
@@ -560,7 +601,7 @@ mod tests {
         let (a, mut query) = system_state.get_mut(&mut world);
         assert_eq!(*a, A(42), "returned resource matches initial value");
         assert_eq!(
-            *query.single_mut().unwrap(),
+            *query.single_mut(),
             B(7),
             "returned component matches initial value"
         );
@@ -577,18 +618,18 @@ mod tests {
         let mut system_state: SystemState<Query<&A, Changed<A>>> = SystemState::new(&mut world);
         {
             let query = system_state.get(&world);
-            assert_eq!(*query.single().unwrap(), A(1));
+            assert_eq!(*query.single(), A(1));
         }
 
         {
             let query = system_state.get(&world);
-            assert!(query.single().is_err());
+            assert!(query.get_single().is_err());
         }
 
         world.entity_mut(entity).get_mut::<A>().unwrap().0 = 2;
         {
             let query = system_state.get(&world);
-            assert_eq!(*query.single().unwrap(), A(2));
+            assert_eq!(*query.single(), A(2));
         }
     }
 
@@ -632,4 +673,199 @@ mod tests {
             );
         }
     }
+
+    /// this test exists to show that read-only world-only queries can return data that lives as long as 'world
+    #[test]
+    #[allow(unused)]
+    fn long_life_test() {
+        struct Holder<'w> {
+            value: &'w A,
+        }
+
+        struct State {
+            state: SystemState<Res<'static, A>>,
+            state_q: SystemState<Query<'static, 'static, &'static A>>,
+        }
+
+        impl State {
+            fn hold_res<'w>(&mut self, world: &'w World) -> Holder<'w> {
+                let a = self.state.get(world);
+                Holder {
+                    value: a.into_inner(),
+                }
+            }
+            fn hold_component<'w>(&mut self, world: &'w World, entity: Entity) -> Holder<'w> {
+                let q = self.state_q.get(world);
+                let a = q.get(entity).unwrap();
+                Holder { value: a }
+            }
+            fn hold_components<'w>(&mut self, world: &'w World) -> Vec<Holder<'w>> {
+                let mut components = Vec::new();
+                let q = self.state_q.get(world);
+                for a in q.iter() {
+                    components.push(Holder { value: a });
+                }
+                components
+            }
+        }
+    }
 }
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// struct A(usize);
+/// fn system(mut query: Query<&mut A>, e: Res<Entity>) {
+///     let mut iter = query.iter_mut();
+///     let a = &mut *iter.next().unwrap();
+///
+///     let mut iter2 = query.iter_mut();
+///     let b = &mut *iter2.next().unwrap();
+///
+///     // this should fail to compile
+///     println!("{}", a.0);
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_query_iter_lifetime_safety_test() {}
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// struct A(usize);
+/// fn system(mut query: Query<&mut A>, e: Res<Entity>) {
+///     let mut a1 = query.get_mut(*e).unwrap();
+///     let mut a2 = query.get_mut(*e).unwrap();
+///     // this should fail to compile
+///     println!("{} {}", a1.0, a2.0);
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_query_get_lifetime_safety_test() {}
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// struct A(usize);
+/// fn query_set(mut queries: QuerySet<(QueryState<&mut A>, QueryState<&A>)>, e: Res<Entity>) {
+///     let mut q2 = queries.q0();
+///     let mut iter2 = q2.iter_mut();
+///     let mut b = iter2.next().unwrap();
+///
+///     let q1 = queries.q1();
+///     let mut iter = q1.iter();
+///     let a = &*iter.next().unwrap();
+///
+///     // this should fail to compile
+///     b.0 = a.0
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_query_set_iter_lifetime_safety_test() {}
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// struct A(usize);
+/// fn query_set(mut queries: QuerySet<(QueryState<&mut A>, QueryState<&A>)>, e: Res<Entity>) {
+///     let q1 = queries.q1();
+///     let mut iter = q1.iter();
+///     let a = &*iter.next().unwrap();
+///
+///     let mut q2 = queries.q0();
+///     let mut iter2 = q2.iter_mut();
+///     let mut b = iter2.next().unwrap();
+///
+///     // this should fail to compile
+///     b.0 = a.0;
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_query_set_iter_flip_lifetime_safety_test() {}
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// struct A(usize);
+/// fn query_set(mut queries: QuerySet<(QueryState<&mut A>, QueryState<&A>)>, e: Res<Entity>) {
+///     let mut q2 = queries.q0();
+///     let mut b = q2.get_mut(*e).unwrap();
+///
+///     let q1 = queries.q1();
+///     let a = q1.get(*e).unwrap();
+///
+///     // this should fail to compile
+///     b.0 = a.0
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_query_set_get_lifetime_safety_test() {}
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// struct A(usize);
+/// fn query_set(mut queries: QuerySet<(QueryState<&mut A>, QueryState<&A>)>, e: Res<Entity>) {
+///     let q1 = queries.q1();
+///     let a = q1.get(*e).unwrap();
+///
+///     let mut q2 = queries.q0();
+///     let mut b = q2.get_mut(*e).unwrap();
+///     // this should fail to compile
+///     b.0 = a.0
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_query_set_get_flip_lifetime_safety_test() {}
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// use bevy_ecs::system::SystemState;
+/// struct A(usize);
+/// struct B(usize);
+/// struct State {
+///     state_r: SystemState<Query<'static, 'static, &'static A>>,
+///     state_w: SystemState<Query<'static, 'static, &'static mut A>>,
+/// }
+///
+/// impl State {
+///     fn get_component<'w>(&mut self, world: &'w mut World, entity: Entity) {
+///         let q1 = self.state_r.get(&world);
+///         let a1 = q1.get(entity).unwrap();
+///
+///         let mut q2 = self.state_w.get_mut(world);
+///         let a2 = q2.get_mut(entity).unwrap();
+///
+///         // this should fail to compile
+///         println!("{}", a1.0);
+///     }
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_state_get_lifetime_safety_test() {}
+
+/// ```compile_fail
+/// use bevy_ecs::prelude::*;
+/// use bevy_ecs::system::SystemState;
+/// struct A(usize);
+/// struct B(usize);
+/// struct State {
+///     state_r: SystemState<Query<'static, 'static, &'static A>>,
+///     state_w: SystemState<Query<'static, 'static, &'static mut A>>,
+/// }
+///
+/// impl State {
+///     fn get_components<'w>(&mut self, world: &'w mut World) {
+///         let q1 = self.state_r.get(&world);
+///         let a1 = q1.iter().next().unwrap();
+///         let mut q2 = self.state_w.get_mut(world);
+///         let a2 = q2.iter_mut().next().unwrap();
+///         // this should fail to compile
+///         println!("{}", a1.0);
+///     }
+/// }
+/// ```
+#[allow(unused)]
+#[cfg(doc)]
+fn system_state_iter_lifetime_safety_test() {}

crates/bevy_ecs/src/system/param_state.rs

@@ -1,36 +0,0 @@
-use crate::system::{SystemParam, SystemParamFetch, SystemParamState, SystemState};
-use crate::world::World;
-
-pub struct ParamState<Param: SystemParam> {
-    state: SystemState,
-    param_state: <Param as SystemParam>::Fetch,
-    change_tick: u32,
-}
-
-impl<Param: SystemParam> ParamState<Param> {
-    pub fn new(world: &mut World) -> Self {
-        let mut state = SystemState::new::<Param>();
-        let config = <Param::Fetch as SystemParamState>::default_config();
-        let param_state = <Param::Fetch as SystemParamState>::init(world, &mut state, config);
-        Self {
-            state,
-            param_state,
-            change_tick: 0,
-        }
-    }
-
-    // TODO: THIS IS SUPER UNSAFE PLEASE DON'T MERGE UNTIL IT IS CONSTRAINED TO READ-ONLY PARAMS
-    pub fn get<'a>(&'a mut self, world: &'a World) -> <Param::Fetch as SystemParamFetch<'a>>::Item {
-        let change_tick = world.increment_change_tick();
-        self.change_tick = change_tick;
-        // TODO: add/implement ReadOnlySystemParam and constrain param here
-        unsafe {
-            <Param::Fetch as SystemParamFetch>::get_param(
-                &mut self.param_state,
-                &mut self.state,
-                world,
-                change_tick,
-            )
-        }
-    }
-}

crates/bevy_ecs/src/system/query.rs

@@ -107,12 +107,12 @@ use thiserror::Error;
 ///
 /// This touches all the basics of queries, make sure to check out all the [`WorldQueries`](WorldQuery)
 /// bevy has to offer.
-pub struct Query<'w, 's, Q: WorldQuery, F: WorldQuery = ()>
+pub struct Query<'world, 'state, Q: WorldQuery, F: WorldQuery = ()>
 where
     F::Fetch: FilterFetch,
 {
-    pub(crate) world: &'w World,
+    pub(crate) world: &'world World,
-    pub(crate) state: &'s QueryState<Q, F>,
+    pub(crate) state: &'state QueryState<Q, F>,
     pub(crate) last_change_tick: u32,
     pub(crate) change_tick: u32,
 }
@@ -146,7 +146,7 @@ where
     ///
     /// This can only be called for read-only queries, see [`Self::iter_mut`] for write-queries.
     #[inline]
-    pub fn iter(&self) -> QueryIter<'w, 's, Q, F>
+    pub fn iter(&'s self) -> QueryIter<'w, 's, Q, F>
     where
         Q::Fetch: ReadOnlyFetch,
     {
@@ -158,6 +158,17 @@ where
         }
     }
 
+    /// Returns an [`Iterator`] over the query results.
+    #[inline]
+    pub fn iter_mut(&mut self) -> QueryIter<'_, '_, Q, F> {
+        // SAFE: system runs without conflicts with other systems.
+        // same-system queries have runtime borrow checks when they conflict
+        unsafe {
+            self.state
+                .iter_unchecked_manual(self.world, self.last_change_tick, self.change_tick)
+        }
+    }
+
     /// Returns an [`Iterator`] over all possible combinations of `K` query results without repetition.
     /// This can only be called for read-only queries
     ///
@@ -166,7 +177,7 @@ where
     /// - if K < N: all possible K-sized combinations of query results, without repetition
     /// - if K > N: empty set (no K-sized combinations exist)
     #[inline]
-    pub fn iter_combinations<const K: usize>(&self) -> QueryCombinationIter<'w, 's, Q, F, K>
+    pub fn iter_combinations<const K: usize>(&self) -> QueryCombinationIter<'_, '_, Q, F, K>
     where
         Q::Fetch: ReadOnlyFetch,
     {
@@ -181,17 +192,6 @@ where
         }
     }
 
-    /// Returns an [`Iterator`] over the query results.
-    #[inline]
-    pub fn iter_mut(&mut self) -> QueryIter<'w, 's, Q, F> {
-        // SAFE: system runs without conflicts with other systems.
-        // same-system queries have runtime borrow checks when they conflict
-        unsafe {
-            self.state
-                .iter_unchecked_manual(self.world, self.last_change_tick, self.change_tick)
-        }
-    }
-
     /// Iterates over all possible combinations of `K` query results without repetition.
     ///
     /// The returned value is not an `Iterator`, because that would lead to aliasing of mutable references.
@@ -216,7 +216,7 @@ where
     #[inline]
     pub fn iter_combinations_mut<const K: usize>(
         &mut self,
-    ) -> QueryCombinationIter<'w, 's, Q, F, K> {
+    ) -> QueryCombinationIter<'_, '_, Q, F, K> {
         // SAFE: system runs without conflicts with other systems.
         // same-system queries have runtime borrow checks when they conflict
         unsafe {
@@ -235,7 +235,7 @@ where
     /// This function makes it possible to violate Rust's aliasing guarantees. You must make sure
     /// this call does not result in multiple mutable references to the same component
     #[inline]
-    pub unsafe fn iter_unsafe(&self) -> QueryIter<'w, 's, Q, F> {
+    pub unsafe fn iter_unsafe(&self) -> QueryIter<'_, '_, Q, F> {
         // SEMI-SAFE: system runs without conflicts with other systems.
         // same-system queries have runtime borrow checks when they conflict
         self.state
@@ -251,7 +251,7 @@ where
     #[inline]
     pub unsafe fn iter_combinations_unsafe<const K: usize>(
         &self,
-    ) -> QueryCombinationIter<'w, 's, Q, F, K> {
+    ) -> QueryCombinationIter<'_, '_, Q, F, K> {
         // SEMI-SAFE: system runs without conflicts with other systems.
         // same-system queries have runtime borrow checks when they conflict
         self.state.iter_combinations_unchecked_manual(
@@ -266,7 +266,7 @@ where
     ///
     /// This can only be called for read-only queries, see [`Self::for_each_mut`] for write-queries.
     #[inline]
-    pub fn for_each(&self, f: impl FnMut(<Q::Fetch as Fetch<'w, 's>>::Item))
+    pub fn for_each(&'s self, f: impl FnMut(<Q::Fetch as Fetch<'w, 's>>::Item))
     where
         Q::Fetch: ReadOnlyFetch,
     {
@@ -285,7 +285,7 @@ where
     /// Runs `f` on each query result. This is faster than the equivalent iter() method, but cannot
     /// be chained like a normal [`Iterator`].
     #[inline]
-    pub fn for_each_mut(&mut self, f: impl FnMut(<Q::Fetch as Fetch<'w, 's>>::Item)) {
+    pub fn for_each_mut<'a>(&'a mut self, f: impl FnMut(<Q::Fetch as Fetch<'a, 'a>>::Item)) {
         // SAFE: system runs without conflicts with other systems. same-system queries have runtime
         // borrow checks when they conflict
         unsafe {
@@ -304,7 +304,7 @@ where
     /// write-queries.
     #[inline]
     pub fn par_for_each(
-        &self,
+        &'s self,
         task_pool: &TaskPool,
         batch_size: usize,
         f: impl Fn(<Q::Fetch as Fetch<'w, 's>>::Item) + Send + Sync + Clone,
@@ -327,11 +327,11 @@ where
 
     /// Runs `f` on each query result in parallel using the given task pool.
     #[inline]
-    pub fn par_for_each_mut(
+    pub fn par_for_each_mut<'a>(
-        &mut self,
+        &'a mut self,
         task_pool: &TaskPool,
         batch_size: usize,
-        f: impl Fn(<Q::Fetch as Fetch<'w, 's>>::Item) + Send + Sync + Clone,
+        f: impl Fn(<Q::Fetch as Fetch<'a, 'a>>::Item) + Send + Sync + Clone,
     ) {
         // SAFE: system runs without conflicts with other systems. same-system queries have runtime
         // borrow checks when they conflict
@@ -351,7 +351,10 @@ where
     ///
     /// This can only be called for read-only queries, see [`Self::get_mut`] for write-queries.
     #[inline]
-    pub fn get(&self, entity: Entity) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QueryEntityError>
+    pub fn get(
+        &'s self,
+        entity: Entity,
+    ) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QueryEntityError>
     where
         Q::Fetch: ReadOnlyFetch,
     {
@@ -372,7 +375,7 @@ where
     pub fn get_mut(
         &mut self,
         entity: Entity,
-    ) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QueryEntityError> {
+    ) -> Result<<Q::Fetch as Fetch>::Item, QueryEntityError> {
         // SAFE: system runs without conflicts with other systems.
         // same-system queries have runtime borrow checks when they conflict
         unsafe {
@@ -393,7 +396,7 @@ where
     /// this call does not result in multiple mutable references to the same component
     #[inline]
     pub unsafe fn get_unchecked(
-        &'s self,
+        &self,
         entity: Entity,
     ) -> Result<<Q::Fetch as Fetch>::Item, QueryEntityError> {
         // SEMI-SAFE: system runs without conflicts with other systems.
@@ -442,7 +445,7 @@ where
     pub fn get_component_mut<T: Component>(
         &mut self,
         entity: Entity,
-    ) -> Result<Mut<'w, T>, QueryComponentError> {
+    ) -> Result<Mut<'_, T>, QueryComponentError> {
         // SAFE: unique access to query (preventing aliased access)
         unsafe { self.get_component_unchecked_mut(entity) }
     }
@@ -459,7 +462,7 @@ where
     pub unsafe fn get_component_unchecked_mut<T: Component>(
         &self,
         entity: Entity,
-    ) -> Result<Mut<'w, T>, QueryComponentError> {
+    ) -> Result<Mut<'_, T>, QueryComponentError> {
         let world = self.world;
         let entity_ref = world
             .get_entity(entity)
@@ -485,6 +488,33 @@ where
         }
     }
 
+    /// Gets the result of a single-result query.
+    ///
+    /// Assumes this query has only one result and panics if there are no or multiple results.
+    /// Use [`Self::get_single`] to handle the error cases explicitly
+    ///
+    /// # Example
+    ///
+    /// ```
+    ///  # use bevy_ecs::prelude::{IntoSystem, Query, With};
+    /// struct Player;
+    /// struct Position(f32, f32);
+    /// fn player_system(query: Query<&Position, With<Player>>) {
+    ///     let player_position = query.single();
+    ///     // do something with player_position
+    /// }
+    /// # let _check_that_its_a_system = player_system.system();
+    /// ```
+    ///
+    /// This can only be called for read-only queries, see [`Self::single_mut`] for write-queries.
+    #[track_caller]
+    pub fn single(&'s self) -> <Q::Fetch as Fetch<'w, 's>>::Item
+    where
+        Q::Fetch: ReadOnlyFetch,
+    {
+        self.get_single().unwrap()
+    }
+
     /// Gets the result of a single-result query.
     ///
     /// If the query has exactly one result, returns the result inside `Ok`
@@ -494,27 +524,28 @@ where
     /// # Examples
     ///
     /// ```
+    ///  # use bevy_ecs::prelude::{IntoSystem, With};
     ///  # use bevy_ecs::system::{Query, QuerySingleError};
-    ///  # use bevy_ecs::prelude::IntoSystem;
+    /// struct Player;
-    /// struct PlayerScore(i32);
+    /// struct Position(f32, f32);
-    /// fn player_scoring_system(query: Query<&PlayerScore>) {
+    /// fn player_system(query: Query<&Position, With<Player>>) {
-    ///     match query.single() {
+    ///     match query.get_single() {
-    ///         Ok(PlayerScore(score)) => {
+    ///         Ok(position) => {
-    ///             // do something with score
+    ///             // do something with position
     ///         }
     ///         Err(QuerySingleError::NoEntities(_)) => {
-    ///             // no PlayerScore
+    ///             // no position with Player
     ///         }
     ///         Err(QuerySingleError::MultipleEntities(_)) => {
-    ///             // multiple PlayerScore
+    ///             // multiple position with Player
     ///         }
     ///     }
     /// }
-    /// # let _check_that_its_a_system = player_scoring_system.system();
+    /// # let _check_that_its_a_system = player_system.system();
     /// ```
     ///
-    /// This can only be called for read-only queries, see [`Self::single_mut`] for write-queries.
+    /// This can only be called for read-only queries, see [`Self::get_single_mut`] for write-queries.
-    pub fn single(&self) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QuerySingleError>
+    pub fn get_single(&'s self) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QuerySingleError>
     where
         Q::Fetch: ReadOnlyFetch,
     {
@@ -531,9 +562,18 @@ where
         }
     }
 
+    /// Gets the query result if it is only a single result, otherwise panics
+    /// If you want to handle the error case yourself you can use the [`Self::get_single_mut`] variant.
+    #[track_caller]
+    pub fn single_mut(&mut self) -> <Q::Fetch as Fetch<'_, '_>>::Item {
+        self.get_single_mut().unwrap()
+    }
+
     /// Gets the query result if it is only a single result, otherwise returns a
     /// [`QuerySingleError`].
-    pub fn single_mut(&mut self) -> Result<<Q::Fetch as Fetch<'w, 's>>::Item, QuerySingleError> {
+    pub fn get_single_mut(
+        &mut self,
+    ) -> Result<<Q::Fetch as Fetch<'_, '_>>::Item, QuerySingleError> {
         let mut query = self.iter_mut();
         let first = query.next();
         let extra = query.next().is_some();

crates/bevy_ecs/src/system/system.rs

@@ -24,7 +24,7 @@ impl SystemId {
 ///
 /// Systems are functions with all arguments implementing [SystemParam](crate::system::SystemParam).
 ///
-/// Systems are added to an application using `AppBuilder::add_system(my_system.system())`
+/// Systems are added to an application using `App::add_system(my_system)`
 /// or similar methods, and will generally run once per pass of the main loop.
 ///
 /// Systems are executed in parallel, in opportunistic order; data access is managed automatically.

crates/bevy_ecs/src/system/system_param.rs

@@ -27,13 +27,12 @@ use std::{
 ///
 /// ```
 /// # use bevy_ecs::prelude::*;
-/// # use std::marker::PhantomData;
+/// use std::marker::PhantomData;
 /// use bevy_ecs::system::SystemParam;
 ///
 /// #[derive(SystemParam)]
-/// struct MyParam<'s, 'w> {
+/// struct MyParam<'w, 's> {
 ///     foo: Res<'w, usize>,
-///     // TODO: this isn't ideal ... maybe the SystemParam derive can be smarter about world and state lifetimes?
 ///     #[system_param(ignore)]
 ///     marker: PhantomData<&'s usize>,
 /// }
@@ -45,7 +44,7 @@ use std::{
 /// # my_system.system();
 /// ```
 pub trait SystemParam: Sized {
-    type Fetch: for<'s, 'w> SystemParamFetch<'s, 'w>;
+    type Fetch: for<'w, 's> SystemParamFetch<'w, 's>;
 }
 
 /// The state of a [`SystemParam`].
@@ -84,21 +83,21 @@ pub unsafe trait SystemParamState: Send + Sync + 'static {
 /// This must only be implemented for [`SystemParamFetch`] impls that exclusively read the World passed in to [`SystemParamFetch::get_param`]
 pub unsafe trait ReadOnlySystemParamFetch {}
 
-pub trait SystemParamFetch<'s, 'w>: SystemParamState {
+pub trait SystemParamFetch<'world, 'state>: SystemParamState {
     type Item;
     /// # Safety
     ///
     /// This call might access any of the input parameters in an unsafe way. Make sure the data
     /// access is safe in the context of the system scheduler.
     unsafe fn get_param(
-        state: &'s mut Self,
+        state: &'state mut Self,
         system_meta: &SystemMeta,
-        world: &'w World,
+        world: &'world World,
         change_tick: u32,
     ) -> Self::Item;
 }
 
-impl<'s, 'w, Q: WorldQuery + 'static, F: WorldQuery + 'static> SystemParam for Query<'w, 's, Q, F>
+impl<'w, 's, Q: WorldQuery + 'static, F: WorldQuery + 'static> SystemParam for Query<'w, 's, Q, F>
 where
     F::Fetch: FilterFetch,
 {
@@ -150,7 +149,7 @@ where
     fn default_config() {}
 }
 
-impl<'s, 'w, Q: WorldQuery + 'static, F: WorldQuery + 'static> SystemParamFetch<'s, 'w>
+impl<'w, 's, Q: WorldQuery + 'static, F: WorldQuery + 'static> SystemParamFetch<'w, 's>
     for QueryState<Q, F>
 where
     F::Fetch: FilterFetch,
@@ -189,7 +188,13 @@ fn assert_component_access_compatibility(
                 query_type, filter_type, system_name, accesses);
 }
 
-pub struct QuerySet<T>(T);
+pub struct QuerySet<'w, 's, T> {
+    query_states: &'s T,
+    world: &'w World,
+    last_change_tick: u32,
+    change_tick: u32,
+}
+
 pub struct QuerySetState<T>(T);
 
 impl_query_set!();
@@ -254,7 +259,7 @@ impl<'w, T: Component> AsRef<T> for Res<'w, T> {
     }
 }
 
-/// The [`SystemParamState`] of [`Res`].
+/// The [`SystemParamState`] of [`Res<T>`].
 pub struct ResState<T> {
     component_id: ComponentId,
     marker: PhantomData<T>,
@@ -295,7 +300,7 @@ unsafe impl<T: Component> SystemParamState for ResState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for ResState<T> {
+impl<'w, 's, T: Component> SystemParamFetch<'w, 's> for ResState<T> {
     type Item = Res<'w, T>;
 
     #[inline]
@@ -323,7 +328,8 @@ impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for ResState<T> {
     }
 }
 
-/// The [`SystemParamState`] of `Option<Res<T>>`.
+/// The [`SystemParamState`] of [`Option<Res<T>>`].
+/// See: [`Res<T>`]
 pub struct OptionResState<T>(ResState<T>);
 
 impl<'a, T: Component> SystemParam for Option<Res<'a, T>> {
@@ -343,7 +349,7 @@ unsafe impl<T: Component> SystemParamState for OptionResState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for OptionResState<T> {
+impl<'w, 's, T: Component> SystemParamFetch<'w, 's> for OptionResState<T> {
     type Item = Option<Res<'w, T>>;
 
     #[inline]
@@ -364,7 +370,7 @@ impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for OptionResState<T> {
     }
 }
 
-/// The [`SystemParamState`] of [`ResMut`].
+/// The [`SystemParamState`] of [`ResMut<T>`].
 pub struct ResMutState<T> {
     component_id: ComponentId,
     marker: PhantomData<T>,
@@ -409,7 +415,7 @@ unsafe impl<T: Component> SystemParamState for ResMutState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for ResMutState<T> {
+impl<'w, 's, T: Component> SystemParamFetch<'w, 's> for ResMutState<T> {
     type Item = ResMut<'w, T>;
 
     #[inline]
@@ -439,7 +445,8 @@ impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for ResMutState<T> {
     }
 }
 
-/// The [`SystemParamState`] of `Option<ResMut<T>>`.
+/// The [`SystemParamState`] of [`Option<ResMut<T>>`].
+/// See: [`ResMut<T>`]
 pub struct OptionResMutState<T>(ResMutState<T>);
 
 impl<'a, T: Component> SystemParam for Option<ResMut<'a, T>> {
@@ -456,7 +463,7 @@ unsafe impl<T: Component> SystemParamState for OptionResMutState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for OptionResMutState<T> {
+impl<'w, 's, T: Component> SystemParamFetch<'w, 's> for OptionResMutState<T> {
     type Item = Option<ResMut<'w, T>>;
 
     #[inline]
@@ -479,7 +486,7 @@ impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for OptionResMutState<T> {
     }
 }
 
-impl<'s, 'w> SystemParam for Commands<'s, 'w> {
+impl<'w, 's> SystemParam for Commands<'w, 's> {
     type Fetch = CommandQueue;
 }
 
@@ -501,8 +508,8 @@ unsafe impl SystemParamState for CommandQueue {
     fn default_config() {}
 }
 
-impl<'s, 'w> SystemParamFetch<'s, 'w> for CommandQueue {
+impl<'w, 's> SystemParamFetch<'w, 's> for CommandQueue {
-    type Item = Commands<'s, 'w>;
+    type Item = Commands<'w, 's>;
 
     #[inline]
     unsafe fn get_param(
@@ -571,7 +578,7 @@ impl<'a, T: Component> DerefMut for Local<'a, T> {
     }
 }
 
-/// The [`SystemParamState`] of [`Local`].
+/// The [`SystemParamState`] of [`Local<T>`].
 pub struct LocalState<T: Component>(T);
 
 impl<'a, T: Component + FromWorld> SystemParam for Local<'a, T> {
@@ -591,7 +598,7 @@ unsafe impl<T: Component + FromWorld> SystemParamState for LocalState<T> {
     }
 }
 
-impl<'s, 'w, T: Component + FromWorld> SystemParamFetch<'s, 'w> for LocalState<T> {
+impl<'w, 's, T: Component + FromWorld> SystemParamFetch<'w, 's> for LocalState<T> {
     type Item = Local<'s, T>;
 
     #[inline]
@@ -639,7 +646,7 @@ impl<'a, T> RemovedComponents<'a, T> {
 // SAFE: Only reads World components
 unsafe impl<T: Component> ReadOnlySystemParamFetch for RemovedComponentsState<T> {}
 
-/// The [`SystemParamState`] of [`RemovedComponents`].
+/// The [`SystemParamState`] of [`RemovedComponents<T>`].
 pub struct RemovedComponentsState<T> {
     component_id: ComponentId,
     marker: PhantomData<T>,
@@ -664,7 +671,7 @@ unsafe impl<T: Component> SystemParamState for RemovedComponentsState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: Component> SystemParamFetch<'s, 'w> for RemovedComponentsState<T> {
+impl<'w, 's, T: Component> SystemParamFetch<'w, 's> for RemovedComponentsState<T> {
     type Item = RemovedComponents<'w, T>;
 
     #[inline]
@@ -736,7 +743,7 @@ impl<'w, T: 'static> Deref for NonSend<'w, T> {
     }
 }
 
-/// The [`SystemParamState`] of [`NonSend`].
+/// The [`SystemParamState`] of [`NonSend<T>`].
 pub struct NonSendState<T> {
     component_id: ComponentId,
     marker: PhantomData<fn() -> T>,
@@ -779,7 +786,7 @@ unsafe impl<T: 'static> SystemParamState for NonSendState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: 'static> SystemParamFetch<'s, 'w> for NonSendState<T> {
+impl<'w, 's, T: 'static> SystemParamFetch<'w, 's> for NonSendState<T> {
     type Item = NonSend<'w, T>;
 
     #[inline]
@@ -809,10 +816,11 @@ impl<'s, 'w, T: 'static> SystemParamFetch<'s, 'w> for NonSendState<T> {
     }
 }
 
-/// The [`SystemParamState`] of `Option<NonSend<T>>`.
+/// The [`SystemParamState`] of [`Option<NonSend<T>>`].
+/// See: [`NonSend<T>`]
 pub struct OptionNonSendState<T>(NonSendState<T>);
 
-impl<'a, T: Component> SystemParam for Option<NonSend<'a, T>> {
+impl<'w, T: 'static> SystemParam for Option<NonSend<'w, T>> {
     type Fetch = OptionNonSendState<T>;
 }
 
@@ -829,7 +837,7 @@ unsafe impl<T: 'static> SystemParamState for OptionNonSendState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: 'static> SystemParamFetch<'s, 'w> for OptionNonSendState<T> {
+impl<'w, 's, T: 'static> SystemParamFetch<'w, 's> for OptionNonSendState<T> {
     type Item = Option<NonSend<'w, T>>;
 
     #[inline]
@@ -851,7 +859,7 @@ impl<'s, 'w, T: 'static> SystemParamFetch<'s, 'w> for OptionNonSendState<T> {
     }
 }
 
-/// The [`SystemParamState`] of [`NonSendMut`].
+/// The [`SystemParamState`] of [`NonSendMut<T>`].
 pub struct NonSendMutState<T> {
     component_id: ComponentId,
     marker: PhantomData<fn() -> T>,
@@ -869,7 +877,7 @@ unsafe impl<T: 'static> SystemParamState for NonSendMutState<T> {
     fn init(world: &mut World, system_meta: &mut SystemMeta, _config: Self::Config) -> Self {
         system_meta.set_non_send();
 
-        let component_id = world.components.get_or_insert_non_send_resource_id::<T>();
+        let component_id = world.initialize_non_send_resource::<T>();
         let combined_access = system_meta.component_access_set.combined_access_mut();
         if combined_access.has_write(component_id) {
             panic!(
@@ -898,7 +906,7 @@ unsafe impl<T: 'static> SystemParamState for NonSendMutState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: 'static> SystemParamFetch<'s, 'w> for NonSendMutState<T> {
+impl<'w, 's, T: 'static> SystemParamFetch<'w, 's> for NonSendMutState<T> {
     type Item = NonSendMut<'w, T>;
 
     #[inline]
@@ -929,7 +937,8 @@ impl<'s, 'w, T: 'static> SystemParamFetch<'s, 'w> for NonSendMutState<T> {
     }
 }
 
-/// The [`SystemParamState`] of `Option<NonSendMut<T>>`.
+/// The [`SystemParamState`] of [`Option<NonSendMut<T>>`].
+/// See: [`NonSendMut<T>`]
 pub struct OptionNonSendMutState<T>(NonSendMutState<T>);
 
 impl<'a, T: 'static> SystemParam for Option<NonSendMut<'a, T>> {
@@ -946,7 +955,7 @@ unsafe impl<T: 'static> SystemParamState for OptionNonSendMutState<T> {
     fn default_config() {}
 }
 
-impl<'s, 'w, T: 'static> SystemParamFetch<'s, 'w> for OptionNonSendMutState<T> {
+impl<'w, 's, T: 'static> SystemParamFetch<'w, 's> for OptionNonSendMutState<T> {
     type Item = Option<NonSendMut<'w, T>>;
 
     #[inline]
@@ -991,7 +1000,7 @@ unsafe impl SystemParamState for ArchetypesState {
     fn default_config() {}
 }
 
-impl<'s, 'w> SystemParamFetch<'s, 'w> for ArchetypesState {
+impl<'w, 's> SystemParamFetch<'w, 's> for ArchetypesState {
     type Item = &'w Archetypes;
 
     #[inline]
@@ -1026,7 +1035,7 @@ unsafe impl SystemParamState for ComponentsState {
     fn default_config() {}
 }
 
-impl<'s, 'w> SystemParamFetch<'s, 'w> for ComponentsState {
+impl<'w, 's> SystemParamFetch<'w, 's> for ComponentsState {
     type Item = &'w Components;
 
     #[inline]
@@ -1061,7 +1070,7 @@ unsafe impl SystemParamState for EntitiesState {
     fn default_config() {}
 }
 
-impl<'s, 'w> SystemParamFetch<'s, 'w> for EntitiesState {
+impl<'w, 's> SystemParamFetch<'w, 's> for EntitiesState {
     type Item = &'w Entities;
 
     #[inline]
@@ -1096,7 +1105,7 @@ unsafe impl SystemParamState for BundlesState {
     fn default_config() {}
 }
 
-impl<'s, 'w> SystemParamFetch<'s, 'w> for BundlesState {
+impl<'w, 's> SystemParamFetch<'w, 's> for BundlesState {
     type Item = &'w Bundles;
 
     #[inline]
@@ -1123,7 +1132,7 @@ impl SystemParam for SystemChangeTick {
     type Fetch = SystemChangeTickState;
 }
 
-/// The [`SystemParamState`] of [`SystemChangeTickState`].
+/// The [`SystemParamState`] of [`SystemChangeTick`].
 pub struct SystemChangeTickState {}
 
 unsafe impl SystemParamState for SystemChangeTickState {
@@ -1136,7 +1145,7 @@ unsafe impl SystemParamState for SystemChangeTickState {
     fn default_config() {}
 }
 
-impl<'s, 'w> SystemParamFetch<'s, 'w> for SystemChangeTickState {
+impl<'w, 's> SystemParamFetch<'w, 's> for SystemChangeTickState {
     type Item = SystemChangeTick;
 
     unsafe fn get_param(
@@ -1163,7 +1172,7 @@ macro_rules! impl_system_param_tuple {
 
         #[allow(unused_variables)]
         #[allow(non_snake_case)]
-        impl<'s, 'w, $($param: SystemParamFetch<'s, 'w>),*> SystemParamFetch<'s, 'w> for ($($param,)*) {
+        impl<'w, 's, $($param: SystemParamFetch<'w, 's>),*> SystemParamFetch<'w, 's> for ($($param,)*) {
             type Item = ($($param::Item,)*);
 
             #[inline]

crates/bevy_ecs/src/world/entity_ref.rs

@@ -1,5 +1,5 @@
 use crate::{
-    archetype::{Archetype, ArchetypeId, Archetypes, ComponentStatus},
+    archetype::{Archetype, ArchetypeId, Archetypes},
     bundle::{Bundle, BundleInfo},
     change_detection::Ticks,
     component::{Component, ComponentId, ComponentTicks, Components, StorageType},
@@ -189,112 +189,29 @@ impl<'w> EntityMut<'w> {
             })
     }
 
-    /// # Safety:
-    /// Partially moves the entity to a new archetype based on the provided bundle info
-    /// You must handle the other part of moving the entity yourself
-    unsafe fn get_insert_bundle_info<'a>(
-        entities: &mut Entities,
-        archetypes: &'a mut Archetypes,
-        components: &mut Components,
-        storages: &mut Storages,
-        bundle_info: &BundleInfo,
-        current_location: EntityLocation,
-        entity: Entity,
-    ) -> (&'a Archetype, &'a Vec<ComponentStatus>, EntityLocation) {
-        // SAFE: component ids in `bundle_info` and self.location are valid
-        let new_archetype_id = add_bundle_to_archetype(
-            archetypes,
-            storages,
-            components,
-            current_location.archetype_id,
-            bundle_info,
-        );
-        if new_archetype_id == current_location.archetype_id {
-            let archetype = &archetypes[current_location.archetype_id];
-            let edge = archetype.edges().get_add_bundle(bundle_info.id).unwrap();
-            (archetype, &edge.bundle_status, current_location)
-        } else {
-            let (old_table_row, old_table_id) = {
-                let old_archetype = &mut archetypes[current_location.archetype_id];
-                let result = old_archetype.swap_remove(current_location.index);
-                if let Some(swapped_entity) = result.swapped_entity {
-                    entities.meta[swapped_entity.id as usize].location = current_location;
-                }
-                (result.table_row, old_archetype.table_id())
-            };
-
-            let new_table_id = archetypes[new_archetype_id].table_id();
-
-            let new_location = if old_table_id == new_table_id {
-                archetypes[new_archetype_id].allocate(entity, old_table_row)
-            } else {
-                let (old_table, new_table) = storages.tables.get_2_mut(old_table_id, new_table_id);
-                // PERF: store "non bundle" components in edge, then just move those to avoid
-                // redundant copies
-                let move_result = old_table.move_to_superset_unchecked(old_table_row, new_table);
-
-                let new_location =
-                    archetypes[new_archetype_id].allocate(entity, move_result.new_row);
-                // if an entity was moved into this entity's table spot, update its table row
-                if let Some(swapped_entity) = move_result.swapped_entity {
-                    let swapped_location = entities.get(swapped_entity).unwrap();
-                    archetypes[swapped_location.archetype_id]
-                        .set_entity_table_row(swapped_location.index, old_table_row);
-                }
-                new_location
-            };
-
-            entities.meta[entity.id as usize].location = new_location;
-            let (old_archetype, new_archetype) =
-                archetypes.get_2_mut(current_location.archetype_id, new_archetype_id);
-            let edge = old_archetype
-                .edges()
-                .get_add_bundle(bundle_info.id)
-                .unwrap();
-            (&*new_archetype, &edge.bundle_status, new_location)
-
-            // Sparse set components are intentionally ignored here. They don't need to move
-        }
-    }
-
-    // TODO: move relevant methods to World (add/remove bundle)
     pub fn insert_bundle<T: Bundle>(&mut self, bundle: T) -> &mut Self {
         let change_tick = self.world.change_tick();
         let bundle_info = self
             .world
             .bundles
             .init_info::<T>(&mut self.world.components);
-
+        let mut bundle_inserter = bundle_info.get_bundle_inserter(
-        let (archetype, bundle_status, new_location) = unsafe {
+            &mut self.world.entities,
-            Self::get_insert_bundle_info(
+            &mut self.world.archetypes,
-                &mut self.world.entities,
+            &mut self.world.components,
-                &mut self.world.archetypes,
+            &mut self.world.storages,
-                &mut self.world.components,
+            self.location.archetype_id,
-                &mut self.world.storages,
+            change_tick,
-                bundle_info,
+        );
-                self.location,
+        // SAFE: location matches current entity. `T` matches `bundle_info`
-                self.entity,
-            )
-        };
-        self.location = new_location;
-
-        let table = &mut self.world.storages.tables[archetype.table_id()];
-        let table_row = archetype.entity_table_row(new_location.index);
-        // SAFE: table row is valid
         unsafe {
-            bundle_info.write_components(
+            self.location = bundle_inserter.insert(self.entity, self.location.index, bundle);
-                &mut self.world.storages.sparse_sets,
+        }
-                self.entity,
+
-                table,
-                table_row,
-                bundle_status,
-                bundle,
-                change_tick,
-            )
-        };
         self
     }
 
+    // TODO: move to BundleInfo
     pub fn remove_bundle<T: Bundle>(&mut self) -> Option<T> {
         let archetypes = &mut self.world.archetypes;
         let storages = &mut self.world.storages;
@@ -340,6 +257,42 @@ impl<'w> EntityMut<'w> {
             })
         };
 
+        unsafe {
+            Self::move_entity_from_remove::<false>(
+                entity,
+                &mut self.location,
+                old_location.archetype_id,
+                old_location,
+                entities,
+                archetypes,
+                storages,
+                new_archetype_id,
+            );
+        }
+
+        Some(result)
+    }
+
+    /// Safety: `new_archetype_id` must have the same or a subset of the components
+    /// in `old_archetype_id`. Probably more safety stuff too, audit a call to
+    /// this fn as if the code here was written inline
+    ///
+    /// when DROP is true removed components will be dropped otherwise they will be forgotten
+    ///
+    // We use a const generic here so that we are less reliant on
+    // inlining for rustc to optimize out the `match DROP`
+    #[allow(clippy::too_many_arguments)]
+    unsafe fn move_entity_from_remove<const DROP: bool>(
+        entity: Entity,
+        self_location: &mut EntityLocation,
+        old_archetype_id: ArchetypeId,
+        old_location: EntityLocation,
+        entities: &mut Entities,
+        archetypes: &mut Archetypes,
+        storages: &mut Storages,
+        new_archetype_id: ArchetypeId,
+    ) {
+        let old_archetype = &mut archetypes[old_archetype_id];
         let remove_result = old_archetype.swap_remove(old_location.index);
         if let Some(swapped_entity) = remove_result.swapped_entity {
             entities.meta[swapped_entity.id as usize].location = old_location;
@@ -349,36 +302,37 @@ impl<'w> EntityMut<'w> {
         let new_archetype = &mut archetypes[new_archetype_id];
 
         let new_location = if old_table_id == new_archetype.table_id() {
-            unsafe { new_archetype.allocate(entity, old_table_row) }
+            new_archetype.allocate(entity, old_table_row)
         } else {
             let (old_table, new_table) = storages
                 .tables
                 .get_2_mut(old_table_id, new_archetype.table_id());
 
-            // SAFE: table_row exists. All "missing" components have been extracted into the bundle
+            // SAFE: old_table_row exists
-            // above and the caller takes ownership
+            let move_result = if DROP {
-            let move_result =
+                old_table.move_to_and_drop_missing_unchecked(old_table_row, new_table)
-                unsafe { old_table.move_to_and_forget_missing_unchecked(old_table_row, new_table) };
+            } else {
+                old_table.move_to_and_forget_missing_unchecked(old_table_row, new_table)
+            };
 
-            // SAFE: new_table_row is a valid position in new_archetype's table
+            // SAFE: move_result.new_row is a valid position in new_archetype's table
-            let new_location = unsafe { new_archetype.allocate(entity, move_result.new_row) };
+            let new_location = new_archetype.allocate(entity, move_result.new_row);
 
             // if an entity was moved into this entity's table spot, update its table row
             if let Some(swapped_entity) = move_result.swapped_entity {
                 let swapped_location = entities.get(swapped_entity).unwrap();
-                let archetype = &mut archetypes[swapped_location.archetype_id];
+                archetypes[swapped_location.archetype_id]
-                archetype.set_entity_table_row(swapped_location.index, old_table_row);
+                    .set_entity_table_row(swapped_location.index, old_table_row);
             }
 
             new_location
         };
 
-        self.location = new_location;
+        *self_location = new_location;
-        entities.meta[self.entity.id as usize].location = new_location;
+        entities.meta[entity.id as usize].location = new_location;
-
-        Some(result)
     }
 
+    // TODO: move to BundleInfo
     /// Remove any components in the bundle that the entity has.
     pub fn remove_bundle_intersection<T: Bundle>(&mut self) {
         let archetypes = &mut self.world.archetypes;
@@ -425,40 +379,18 @@ impl<'w> EntityMut<'w> {
             }
         }
 
-        let remove_result = old_archetype.swap_remove(old_location.index);
+        unsafe {
-        if let Some(swapped_entity) = remove_result.swapped_entity {
+            Self::move_entity_from_remove::<true>(
-            entities.meta[swapped_entity.id as usize].location = old_location;
+                entity,
+                &mut self.location,
+                old_location.archetype_id,
+                old_location,
+                entities,
+                archetypes,
+                storages,
+                new_archetype_id,
+            )
         }
-        let old_table_row = remove_result.table_row;
-        let old_table_id = old_archetype.table_id();
-        let new_archetype = &mut archetypes[new_archetype_id];
-
-        let new_location = if old_table_id == new_archetype.table_id() {
-            unsafe { new_archetype.allocate(entity, old_table_row) }
-        } else {
-            let (old_table, new_table) = storages
-                .tables
-                .get_2_mut(old_table_id, new_archetype.table_id());
-
-            // SAFE: table_row exists
-            let move_result =
-                unsafe { old_table.move_to_and_drop_missing_unchecked(old_table_row, new_table) };
-
-            // SAFE: new_table_row is a valid position in new_archetype's table
-            let new_location = unsafe { new_archetype.allocate(entity, move_result.new_row) };
-
-            // if an entity was moved into this entity's table spot, update its table row
-            if let Some(swapped_entity) = move_result.swapped_entity {
-                let swapped_location = entities.get(swapped_entity).unwrap();
-                archetypes[swapped_location.archetype_id]
-                    .set_entity_table_row(swapped_location.index, old_table_row);
-            }
-
-            new_location
-        };
-
-        self.location = new_location;
-        entities.meta[self.entity.id as usize].location = new_location;
     }
 
     pub fn insert<T: Component>(&mut self, value: T) -> &mut Self {
@@ -531,6 +463,7 @@ impl<'w> EntityMut<'w> {
     }
 }
 
+// TODO: move to Storages?
 /// # Safety
 /// `entity_location` must be within bounds of the given archetype and `entity` must exist inside
 /// the archetype
@@ -560,6 +493,7 @@ unsafe fn get_component(
     }
 }
 
+// TODO: move to Storages?
 /// # Safety
 /// Caller must ensure that `component_id` is valid
 #[inline]
@@ -590,6 +524,7 @@ unsafe fn get_component_and_ticks(
     }
 }
 
+// TODO: move to Storages?
 /// Moves component data out of storage.
 ///
 /// This function leaves the underlying memory unchanged, but the component behind
@@ -671,95 +606,6 @@ fn contains_component_with_id(
     world.archetypes[location.archetype_id].contains(component_id)
 }
 
-/// Adds a bundle to the given archetype and returns the resulting archetype. This could be the same
-/// [ArchetypeId], in the event that adding the given bundle does not result in an Archetype change.
-/// Results are cached in the Archetype Graph to avoid redundant work.
-///
-/// # Safety
-/// components in `bundle_info` must exist
-pub(crate) unsafe fn add_bundle_to_archetype(
-    archetypes: &mut Archetypes,
-    storages: &mut Storages,
-    components: &mut Components,
-    archetype_id: ArchetypeId,
-    bundle_info: &BundleInfo,
-) -> ArchetypeId {
-    if let Some(add_bundle) = archetypes[archetype_id]
-        .edges()
-        .get_add_bundle(bundle_info.id)
-    {
-        return add_bundle.archetype_id;
-    }
-    let mut new_table_components = Vec::new();
-    let mut new_sparse_set_components = Vec::new();
-    let mut bundle_status = Vec::with_capacity(bundle_info.component_ids.len());
-
-    let current_archetype = &mut archetypes[archetype_id];
-    for component_id in bundle_info.component_ids.iter().cloned() {
-        if current_archetype.contains(component_id) {
-            bundle_status.push(ComponentStatus::Mutated);
-        } else {
-            bundle_status.push(ComponentStatus::Added);
-            let component_info = components.get_info_unchecked(component_id);
-            match component_info.storage_type() {
-                StorageType::Table => new_table_components.push(component_id),
-                StorageType::SparseSet => {
-                    storages.sparse_sets.get_or_insert(component_info);
-                    new_sparse_set_components.push(component_id)
-                }
-            }
-        }
-    }
-
-    if new_table_components.is_empty() && new_sparse_set_components.is_empty() {
-        let edges = current_archetype.edges_mut();
-        // the archetype does not change when we add this bundle
-        edges.set_add_bundle(bundle_info.id, archetype_id, bundle_status);
-        archetype_id
-    } else {
-        let table_id;
-        let table_components;
-        let sparse_set_components;
-        // the archetype changes when we add this bundle. prepare the new archetype and storages
-        {
-            let current_archetype = &archetypes[archetype_id];
-            table_components = if new_table_components.is_empty() {
-                // if there are no new table components, we can keep using this table
-                table_id = current_archetype.table_id();
-                current_archetype.table_components().to_vec()
-            } else {
-                new_table_components.extend(current_archetype.table_components());
-                // sort to ignore order while hashing
-                new_table_components.sort();
-                // SAFE: all component ids in `new_table_components` exist
-                table_id = storages
-                    .tables
-                    .get_id_or_insert(&new_table_components, components);
-
-                new_table_components
-            };
-
-            sparse_set_components = if new_sparse_set_components.is_empty() {
-                current_archetype.sparse_set_components().to_vec()
-            } else {
-                new_sparse_set_components.extend(current_archetype.sparse_set_components());
-                // sort to ignore order while hashing
-                new_sparse_set_components.sort();
-                new_sparse_set_components
-            };
-        };
-        let new_archetype_id =
-            archetypes.get_id_or_insert(table_id, table_components, sparse_set_components);
-        // add an edge from the old archetype to the new archetype
-        archetypes[archetype_id].edges_mut().set_add_bundle(
-            bundle_info.id,
-            new_archetype_id,
-            bundle_status,
-        );
-        new_archetype_id
-    }
-}
-
 /// Removes a bundle from the given archetype and returns the resulting archetype (or None if the
 /// removal was invalid). in the event that adding the given bundle does not result in an Archetype
 /// change. Results are cached in the Archetype Graph to avoid redundant work.
@@ -814,7 +660,7 @@ unsafe fn remove_bundle_from_archetype(
                     // graph
                     current_archetype
                         .edges_mut()
-                        .set_remove_bundle(bundle_info.id, None);
+                        .insert_remove_bundle(bundle_info.id, None);
                     return None;
                 }
             }
@@ -853,11 +699,11 @@ unsafe fn remove_bundle_from_archetype(
     if intersection {
         current_archetype
             .edges_mut()
-            .set_remove_bundle_intersection(bundle_info.id, result);
+            .insert_remove_bundle_intersection(bundle_info.id, result);
     } else {
         current_archetype
             .edges_mut()
-            .set_remove_bundle(bundle_info.id, result);
+            .insert_remove_bundle(bundle_info.id, result);
     }
     result
 }

crates/bevy_ecs/src/world/mod.rs

@@ -1,16 +1,15 @@
 mod entity_ref;
-mod pointer;
 mod spawn_batch;
 mod world_cell;
 
+pub use crate::change_detection::Mut;
 pub use entity_ref::*;
-pub use pointer::*;
 pub use spawn_batch::*;
 pub use world_cell::*;
 
 use crate::{
     archetype::{ArchetypeComponentId, ArchetypeComponentInfo, ArchetypeId, Archetypes},
-    bundle::{Bundle, Bundles},
+    bundle::{Bundle, BundleInserter, BundleSpawner, Bundles},
     change_detection::Ticks,
     component::{
         Component, ComponentDescriptor, ComponentId, ComponentTicks, Components, ComponentsError,
@@ -221,8 +220,13 @@ impl World {
         self.get_entity_mut(entity).expect("Entity does not exist")
     }
 
-    /// Returns an EntityMut for an existing entity or creates one if it doesn't exist.
+    /// Returns an [EntityMut] for the given `entity` (if it exists) or spawns one if it doesn't exist.
-    /// This will return `None` if the entity exists with a different generation.
+    /// This will return [None] if the `entity` exists with a different generation.
+    ///
+    /// # Note
+    /// Spawning a specific `entity` value is rarely the right choice. Most apps should favor [`World::spawn`].
+    /// This method should generally only be used for sharing entities across apps, and only when they have a
+    /// scheme worked out to share an ID space (which doesn't happen by default).
     #[inline]
     pub fn get_or_spawn(&mut self, entity: Entity) -> Option<EntityMut> {
         self.flush();
@@ -379,6 +383,7 @@ impl World {
     ///     .id();
     /// let position = world.get::<Position>(entity).unwrap();
     /// assert_eq!(position.x, 0.0);
+    /// ```
     #[inline]
     pub fn get<T: Component>(&self, entity: Entity) -> Option<&T> {
         self.get_entity(entity)?.get()
@@ -400,6 +405,7 @@ impl World {
     ///     .id();
     /// let mut position = world.get_mut::<Position>(entity).unwrap();
     /// position.x = 1.0;
+    /// ```
     #[inline]
     pub fn get_mut<T: Component>(&mut self, entity: Entity) -> Option<Mut<T>> {
         self.get_entity_mut(entity)?.get_mut()
@@ -699,6 +705,127 @@ impl World {
         self.get_non_send_unchecked_mut_with_id(component_id)
     }
 
+    /// For a given batch of ([Entity], [Bundle]) pairs, either spawns each [Entity] with the given
+    /// bundle (if the entity does not exist), or inserts the [Bundle] (if the entity already exists).
+    /// This is faster than doing equivalent operations one-by-one.
+    /// Returns [Ok] if all entities were successfully inserted into or spawned. Otherwise it returns an [Err]
+    /// with a list of entities that could not be spawned or inserted into. A "spawn or insert" operation can
+    /// only fail if an [Entity] is passed in with an "invalid generation" that conflicts with an existing [Entity].
+    ///
+    /// # Note
+    /// Spawning a specific `entity` value is rarely the right choice. Most apps should use [`World::spawn_batch`].
+    /// This method should generally only be used for sharing entities across apps, and only when they have a scheme
+    /// worked out to share an ID space (which doesn't happen by default).
+    ///
+    /// ```
+    /// use bevy_ecs::{entity::Entity, world::World};
+    ///
+    /// let mut world = World::new();
+    /// let e0 = world.spawn().id();
+    /// let e1 = world.spawn().id();
+    /// world.insert_or_spawn_batch(vec![
+    ///   (e0, ("a", 0.0)), // the first entity
+    ///   (e1, ("b", 1.0)), // the second entity
+    /// ]);
+    ///
+    /// assert_eq!(world.get::<f64>(e0), Some(&0.0));
+    /// ```
+    pub fn insert_or_spawn_batch<I, B>(&mut self, iter: I) -> Result<(), Vec<Entity>>
+    where
+        I: IntoIterator,
+        I::IntoIter: Iterator<Item = (Entity, B)>,
+        B: Bundle,
+    {
+        self.flush();
+
+        let iter = iter.into_iter();
+        let change_tick = *self.change_tick.get_mut();
+
+        let bundle_info = self.bundles.init_info::<B>(&mut self.components);
+        enum SpawnOrInsert<'a, 'b> {
+            Spawn(BundleSpawner<'a, 'b>),
+            Insert(BundleInserter<'a, 'b>, ArchetypeId),
+        }
+
+        impl<'a, 'b> SpawnOrInsert<'a, 'b> {
+            fn entities(&mut self) -> &mut Entities {
+                match self {
+                    SpawnOrInsert::Spawn(spawner) => spawner.entities,
+                    SpawnOrInsert::Insert(inserter, _) => inserter.entities,
+                }
+            }
+        }
+        let mut spawn_or_insert = SpawnOrInsert::Spawn(bundle_info.get_bundle_spawner(
+            &mut self.entities,
+            &mut self.archetypes,
+            &mut self.components,
+            &mut self.storages,
+            change_tick,
+        ));
+
+        let mut invalid_entities = Vec::new();
+        for (entity, bundle) in iter {
+            match spawn_or_insert
+                .entities()
+                .alloc_at_without_replacement(entity)
+            {
+                AllocAtWithoutReplacement::Exists(location) => {
+                    match spawn_or_insert {
+                        SpawnOrInsert::Insert(ref mut inserter, archetype)
+                            if location.archetype_id == archetype =>
+                        {
+                            // SAFE: `entity` is valid, `location` matches entity, bundle matches inserter
+                            unsafe { inserter.insert(entity, location.index, bundle) };
+                        }
+                        _ => {
+                            let mut inserter = bundle_info.get_bundle_inserter(
+                                &mut self.entities,
+                                &mut self.archetypes,
+                                &mut self.components,
+                                &mut self.storages,
+                                location.archetype_id,
+                                change_tick,
+                            );
+                            // SAFE: `entity` is valid, `location` matches entity, bundle matches inserter
+                            unsafe { inserter.insert(entity, location.index, bundle) };
+                            spawn_or_insert =
+                                SpawnOrInsert::Insert(inserter, location.archetype_id);
+                        }
+                    };
+                }
+                AllocAtWithoutReplacement::DidNotExist => {
+                    match spawn_or_insert {
+                        SpawnOrInsert::Spawn(ref mut spawner) => {
+                            // SAFE: `entity` is allocated (but non existent), bundle matches inserter
+                            unsafe { spawner.spawn_non_existent(entity, bundle) };
+                        }
+                        _ => {
+                            let mut spawner = bundle_info.get_bundle_spawner(
+                                &mut self.entities,
+                                &mut self.archetypes,
+                                &mut self.components,
+                                &mut self.storages,
+                                change_tick,
+                            );
+                            // SAFE: `entity` is valid, `location` matches entity, bundle matches inserter
+                            unsafe { spawner.spawn_non_existent(entity, bundle) };
+                            spawn_or_insert = SpawnOrInsert::Spawn(spawner);
+                        }
+                    };
+                }
+                AllocAtWithoutReplacement::ExistsWithWrongGeneration => {
+                    invalid_entities.push(entity);
+                }
+            }
+        }
+
+        if invalid_entities.is_empty() {
+            Ok(())
+        } else {
+            Err(invalid_entities)
+        }
+    }
+
     /// Temporarily removes the requested resource from this [World], then re-adds it before
     /// returning. This enables safe mutable access to a resource while still providing mutable
     /// world access
@@ -838,7 +965,7 @@ impl World {
         let resource_archetype = self
             .archetypes
             .archetypes
-            .get_unchecked_mut(ArchetypeId::resource().index());
+            .get_unchecked_mut(ArchetypeId::RESOURCE.index());
         let resource_archetype_components = &mut resource_archetype.components;
         let archetype_component_count = &mut self.archetypes.archetype_component_count;
         let components = &self.components;

crates/bevy_ecs/src/world/pointer.rs

@@ -1 +0,0 @@
-pub use crate::change_detection::Mut;

crates/bevy_ecs/src/world/spawn_batch.rs

@@ -1,9 +1,7 @@
 use crate::{
-    archetype::{Archetype, ArchetypeId, ComponentStatus},
+    bundle::{Bundle, BundleSpawner},
-    bundle::{Bundle, BundleInfo},
+    entity::Entity,
-    entity::{Entities, Entity},
+    world::World,
-    storage::{SparseSets, Table},
-    world::{add_bundle_to_archetype, World},
 };
 
 pub struct SpawnBatchIter<'w, I>
@@ -12,13 +10,7 @@ where
     I::Item: Bundle,
 {
     inner: I,
-    entities: &'w mut Entities,
+    spawner: BundleSpawner<'w, 'w>,
-    archetype: &'w mut Archetype,
-    table: &'w mut Table,
-    sparse_sets: &'w mut SparseSets,
-    bundle_info: &'w BundleInfo,
-    bundle_status: &'w [ComponentStatus],
-    change_tick: u32,
 }
 
 impl<'w, I> SpawnBatchIter<'w, I>
@@ -33,40 +25,22 @@ where
         world.flush();
 
         let (lower, upper) = iter.size_hint();
+        let length = upper.unwrap_or(lower);
 
         let bundle_info = world.bundles.init_info::<I::Item>(&mut world.components);
-
-        let length = upper.unwrap_or(lower);
-        // SAFE: empty archetype exists and bundle components were initialized above
-        let archetype_id = unsafe {
-            add_bundle_to_archetype(
-                &mut world.archetypes,
-                &mut world.storages,
-                &mut world.components,
-                ArchetypeId::empty(),
-                bundle_info,
-            )
-        };
-        let (empty_archetype, archetype) = world
-            .archetypes
-            .get_2_mut(ArchetypeId::empty(), archetype_id);
-        let table = &mut world.storages.tables[archetype.table_id()];
-        archetype.reserve(length);
-        table.reserve(length);
         world.entities.reserve(length as u32);
-        let edge = empty_archetype
+        let mut spawner = bundle_info.get_bundle_spawner(
-            .edges()
+            &mut world.entities,
-            .get_add_bundle(bundle_info.id())
+            &mut world.archetypes,
-            .unwrap();
+            &mut world.components,
+            &mut world.storages,
+            *world.change_tick.get_mut(),
+        );
+        spawner.reserve_storage(length);
+
         Self {
             inner: iter,
-            entities: &mut world.entities,
+            spawner,
-            archetype,
-            table,
-            sparse_sets: &mut world.storages.sparse_sets,
-            bundle_info,
-            change_tick: *world.change_tick.get_mut(),
-            bundle_status: &edge.bundle_status,
         }
     }
 }
@@ -90,24 +64,8 @@ where
 
     fn next(&mut self) -> Option<Entity> {
         let bundle = self.inner.next()?;
-        let entity = self.entities.alloc();
+        // SAFE: bundle matches spawner type
-        // SAFE: component values are immediately written to relevant storages (which have been
+        unsafe { Some(self.spawner.spawn(bundle)) }
-        // allocated)
-        unsafe {
-            let table_row = self.table.allocate(entity);
-            let location = self.archetype.allocate(entity, table_row);
-            self.bundle_info.write_components(
-                self.sparse_sets,
-                entity,
-                self.table,
-                table_row,
-                self.bundle_status,
-                bundle,
-                self.change_tick,
-            );
-            self.entities.meta[entity.id as usize].location = location;
-        }
-        Some(entity)
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {

crates/bevy_ecs/src/world/world_cell.rs

@@ -296,7 +296,7 @@ mod tests {
             .components
             .get_resource_id(TypeId::of::<u32>())
             .unwrap();
-        let resource_archetype = world.archetypes.get(ArchetypeId::resource()).unwrap();
+        let resource_archetype = world.archetypes.get(ArchetypeId::RESOURCE).unwrap();
         let u32_archetype_component_id = resource_archetype
             .get_archetype_component_id(u32_component_id)
             .unwrap();

crates/bevy_render/Cargo.toml

@@ -2,10 +2,6 @@
 name = "bevy_render"
 version = "0.5.0"
 edition = "2018"
-authors = [
-    "Bevy Contributors <bevyengine@gmail.com>",
-    "Carter Anderson <mcanders1@gmail.com>",
-]
 description = "Provides rendering functionality for Bevy Engine"
 homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"

crates/bevy_render/src/camera/camera.rs

@@ -4,9 +4,10 @@ use bevy_ecs::{
     component::Component,
     entity::Entity,
     event::EventReader,
+    prelude::QueryState,
     query::Added,
     reflect::ReflectComponent,
-    system::{Query, QuerySet, Res},
+    system::{QuerySet, Res},
 };
 use bevy_math::{Mat4, Vec2, Vec3};
 use bevy_reflect::{Reflect, ReflectDeserialize};
@@ -70,8 +71,8 @@ pub fn camera_system<T: CameraProjection + Component>(
     mut window_created_events: EventReader<WindowCreated>,
     windows: Res<Windows>,
     mut queries: QuerySet<(
-        Query<(Entity, &mut Camera, &mut T)>,
+        QueryState<(Entity, &mut Camera, &mut T)>,
-        Query<Entity, Added<Camera>>,
+        QueryState<Entity, Added<Camera>>,
     )>,
 ) {
     let mut changed_window_ids = Vec::new();
@@ -99,7 +100,7 @@ pub fn camera_system<T: CameraProjection + Component>(
     for entity in &mut queries.q1().iter() {
         added_cameras.push(entity);
     }
-    for (entity, mut camera, mut camera_projection) in queries.q0_mut().iter_mut() {
+    for (entity, mut camera, mut camera_projection) in queries.q0().iter_mut() {
         if let Some(window) = windows.get(camera.window) {
             if changed_window_ids.contains(&window.id())
                 || added_cameras.contains(&entity)

crates/bevy_render/src/color.rs

@@ -10,6 +10,7 @@ use bevy_math::{Vec3, Vec4};
 use bevy_reflect::{Reflect, ReflectDeserialize};
 use serde::{Deserialize, Serialize};
 use std::ops::{Add, AddAssign, Mul, MulAssign};
+use thiserror::Error;
 
 #[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize, Reflect)]
 #[reflect(PartialEq, Serialize, Deserialize)]
@@ -1070,10 +1071,12 @@ impl Bytes for Color {
 
 impl_render_resource_bytes!(Color);
 
-#[derive(Debug)]
+#[derive(Debug, Error)]
 pub enum HexColorError {
+    #[error("Unexpected length of hex string")]
     Length,
-    Hex(hex::FromHexError),
+    #[error("Error parsing hex value")]
+    Hex(#[from] hex::FromHexError),
 }
 
 fn decode_rgb(data: &[u8]) -> Result<Color, HexColorError> {

crates/bevy_render/src/draw.rs

@@ -164,7 +164,7 @@ pub enum DrawError {
 }
 
 #[derive(SystemParam)]
-pub struct DrawContext<'s, 'w> {
+pub struct DrawContext<'w, 's> {
     pub pipelines: ResMut<'w, Assets<PipelineDescriptor>>,
     pub shaders: ResMut<'w, Assets<Shader>>,
     pub asset_render_resource_bindings: ResMut<'w, AssetRenderResourceBindings>,
@@ -177,7 +177,7 @@ pub struct DrawContext<'s, 'w> {
     marker: PhantomData<&'s usize>,
 }
 
-impl<'s, 'w> DrawContext<'s, 'w> {
+impl<'w, 's> DrawContext<'w, 's> {
     pub fn get_uniform_buffer<T: RenderResource>(
         &mut self,
         render_resource: &T,

crates/bevy_render/src/lib.rs

@@ -14,7 +14,7 @@ pub mod wireframe;
 
 use bevy_ecs::{
     schedule::{ParallelSystemDescriptorCoercion, SystemStage},
-    system::{IntoExclusiveSystem, IntoSystem, Res},
+    system::{IntoExclusiveSystem, Res},
 };
 use bevy_transform::TransformSystem;
 use bevy_utils::tracing::warn;
@@ -174,58 +174,38 @@ impl Plugin for RenderPlugin {
         .init_resource::<RenderResourceBindings>()
         .init_resource::<AssetRenderResourceBindings>()
         .init_resource::<ActiveCameras>()
-        .add_startup_system_to_stage(
+        .add_startup_system_to_stage(StartupStage::PreStartup, check_for_render_resource_context)
-            StartupStage::PreStartup,
+        .add_system_to_stage(CoreStage::PreUpdate, draw::clear_draw_system)
-            check_for_render_resource_context.system(),
+        .add_system_to_stage(CoreStage::PostUpdate, camera::active_cameras_system)
-        )
-        .add_system_to_stage(CoreStage::PreUpdate, draw::clear_draw_system.system())
         .add_system_to_stage(
             CoreStage::PostUpdate,
-            camera::active_cameras_system.system(),
+            camera::camera_system::<OrthographicProjection>.before(RenderSystem::VisibleEntities),
         )
         .add_system_to_stage(
             CoreStage::PostUpdate,
-            camera::camera_system::<OrthographicProjection>
+            camera::camera_system::<PerspectiveProjection>.before(RenderSystem::VisibleEntities),
-                .system()
-                .before(RenderSystem::VisibleEntities),
-        )
-        .add_system_to_stage(
-            CoreStage::PostUpdate,
-            camera::camera_system::<PerspectiveProjection>
-                .system()
-                .before(RenderSystem::VisibleEntities),
         )
         .add_system_to_stage(
             CoreStage::PostUpdate,
             camera::visible_entities_system
-                .system()
                 .label(RenderSystem::VisibleEntities)
                 .after(TransformSystem::TransformPropagate),
         )
+        .add_system_to_stage(RenderStage::RenderResource, shader::shader_update_system)
         .add_system_to_stage(
             RenderStage::RenderResource,
-            shader::shader_update_system.system(),
+            mesh::mesh_resource_provider_system,
         )
         .add_system_to_stage(
             RenderStage::RenderResource,
-            mesh::mesh_resource_provider_system.system(),
+            Texture::texture_resource_system,
-        )
-        .add_system_to_stage(
-            RenderStage::RenderResource,
-            Texture::texture_resource_system.system(),
         )
         .add_system_to_stage(
             RenderStage::RenderGraphSystems,
             render_graph::render_graph_schedule_executor_system.exclusive_system(),
         )
-        .add_system_to_stage(
+        .add_system_to_stage(RenderStage::Draw, pipeline::draw_render_pipelines_system)
-            RenderStage::Draw,
+        .add_system_to_stage(RenderStage::PostRender, shader::clear_shader_defs_system);
-            pipeline::draw_render_pipelines_system.system(),
-        )
-        .add_system_to_stage(
-            RenderStage::PostRender,
-            shader::clear_shader_defs_system.system(),
-        );
 
         if let Some(ref config) = self.base_render_graph_config {
             crate::base::add_base_graph(config, &mut app.world);

crates/bevy_render/src/mesh/mesh.rs

@@ -9,8 +9,9 @@ use bevy_core::cast_slice;
 use bevy_ecs::{
     entity::Entity,
     event::EventReader,
+    prelude::QueryState,
     query::{Changed, With},
-    system::{Local, Query, QuerySet, Res},
+    system::{Local, QuerySet, Res},
     world::Mut,
 };
 use bevy_math::*;
@@ -512,8 +513,8 @@ pub fn mesh_resource_provider_system(
     meshes: Res<Assets<Mesh>>,
     mut mesh_events: EventReader<AssetEvent<Mesh>>,
     mut queries: QuerySet<(
-        Query<&mut RenderPipelines, With<Handle<Mesh>>>,
+        QueryState<&mut RenderPipelines, With<Handle<Mesh>>>,
-        Query<(Entity, &Handle<Mesh>, &mut RenderPipelines), Changed<Handle<Mesh>>>,
+        QueryState<(Entity, &Handle<Mesh>, &mut RenderPipelines), Changed<Handle<Mesh>>>,
     )>,
 ) {
     let mut changed_meshes = HashSet::default();
@@ -573,7 +574,7 @@ pub fn mesh_resource_provider_system(
 
             if let Some(mesh_entities) = state.mesh_entities.get_mut(changed_mesh_handle) {
                 for entity in mesh_entities.entities.iter() {
-                    if let Ok(render_pipelines) = queries.q0_mut().get_mut(*entity) {
+                    if let Ok(render_pipelines) = queries.q0().get_mut(*entity) {
                         update_entity_mesh(
                             render_resource_context,
                             mesh,
@@ -587,7 +588,7 @@ pub fn mesh_resource_provider_system(
     }
 
     // handover buffers to pipeline
-    for (entity, handle, render_pipelines) in queries.q1_mut().iter_mut() {
+    for (entity, handle, render_pipelines) in queries.q1().iter_mut() {
         let mesh_entities = state
             .mesh_entities
             .entry(handle.clone_weak())

crates/bevy_render/src/render_graph/nodes/camera_node.rs

@@ -8,7 +8,7 @@ use crate::{
 };
 use bevy_core::bytes_of;
 use bevy_ecs::{
-    system::{BoxedSystem, IntoSystem, Local, Query, Res, ResMut},
+    system::{BoxedSystem, ConfigurableSystem, Local, Query, Res, ResMut},
     world::World,
 };
 use bevy_transform::prelude::*;
@@ -46,7 +46,7 @@ impl Node for CameraNode {
 
 impl SystemNode for CameraNode {
     fn get_system(&self) -> BoxedSystem {
-        let system = camera_node_system.system().config(|config| {
+        let system = camera_node_system.config(|config| {
             config.0 = Some(CameraNodeState {
                 camera_name: self.camera_name.clone(),
                 command_queue: self.command_queue.clone(),

crates/bevy_render/src/render_graph/nodes/render_resources_node.rs

@@ -13,8 +13,9 @@ use bevy_app::EventReader;
 use bevy_asset::{Asset, AssetEvent, Assets, Handle, HandleId};
 use bevy_ecs::{
     entity::Entity,
+    prelude::QueryState,
     query::{Changed, Or, With},
-    system::{BoxedSystem, IntoSystem, Local, Query, QuerySet, RemovedComponents, Res, ResMut},
+    system::{BoxedSystem, ConfigurableSystem, Local, QuerySet, RemovedComponents, Res, ResMut},
     world::World,
 };
 use bevy_utils::HashMap;
@@ -400,7 +401,7 @@ where
     T: renderer::RenderResources,
 {
     fn get_system(&self) -> BoxedSystem {
-        let system = render_resources_node_system::<T>.system().config(|config| {
+        let system = render_resources_node_system::<T>.config(|config| {
             config.0 = Some(RenderResourcesNodeState {
                 command_queue: self.command_queue.clone(),
                 uniform_buffer_arrays: UniformBufferArrays::<Entity, T>::default(),
@@ -435,8 +436,11 @@ fn render_resources_node_system<T: RenderResources>(
     render_resource_context: Res<Box<dyn RenderResourceContext>>,
     removed: RemovedComponents<T>,
     mut queries: QuerySet<(
-        Query<(Entity, &T, &Visible, &mut RenderPipelines), Or<(Changed<T>, Changed<Visible>)>>,
+        QueryState<
-        Query<(Entity, &T, &Visible, &mut RenderPipelines)>,
+            (Entity, &T, &Visible, &mut RenderPipelines),
+            Or<(Changed<T>, Changed<Visible>)>,
+        >,
+        QueryState<(Entity, &T, &Visible, &mut RenderPipelines)>,
     )>,
 ) {
     let state = state.deref_mut();
@@ -444,7 +448,7 @@ fn render_resources_node_system<T: RenderResources>(
     let render_resource_context = &**render_resource_context;
     uniform_buffer_arrays.begin_update();
     // initialize uniform buffer arrays using the first RenderResources
-    if let Some((_, first, _, _)) = queries.q0_mut().iter_mut().next() {
+    if let Some((_, first, _, _)) = queries.q0().iter_mut().next() {
         uniform_buffer_arrays.initialize(first, render_resource_context);
     }
 
@@ -454,8 +458,7 @@ fn render_resources_node_system<T: RenderResources>(
 
     // handle entities that were waiting for texture loads on the last update
     for entity in std::mem::take(&mut *entities_waiting_for_textures) {
-        if let Ok((entity, uniforms, _visible, mut render_pipelines)) =
+        if let Ok((entity, uniforms, _visible, mut render_pipelines)) = queries.q1().get_mut(entity)
-            queries.q1_mut().get_mut(entity)
         {
             if !setup_uniform_texture_resources::<T>(
                 uniforms,
@@ -467,7 +470,7 @@ fn render_resources_node_system<T: RenderResources>(
         }
     }
 
-    for (entity, uniforms, visible, mut render_pipelines) in queries.q0_mut().iter_mut() {
+    for (entity, uniforms, visible, mut render_pipelines) in queries.q0().iter_mut() {
         if !visible.is_visible {
             continue;
         }
@@ -496,8 +499,7 @@ fn render_resources_node_system<T: RenderResources>(
                 // if the buffer array was resized, write all entities to the new buffer, otherwise
                 // only write changes
                 if resized {
-                    for (entity, uniforms, visible, mut render_pipelines) in
+                    for (entity, uniforms, visible, mut render_pipelines) in queries.q1().iter_mut()
-                        queries.q1_mut().iter_mut()
                     {
                         if !visible.is_visible {
                             continue;
@@ -513,8 +515,7 @@ fn render_resources_node_system<T: RenderResources>(
                         );
                     }
                 } else {
-                    for (entity, uniforms, visible, mut render_pipelines) in
+                    for (entity, uniforms, visible, mut render_pipelines) in queries.q0().iter_mut()
-                        queries.q0_mut().iter_mut()
                     {
                         if !visible.is_visible {
                             continue;
@@ -583,15 +584,13 @@ where
     T: renderer::RenderResources + Asset,
 {
     fn get_system(&self) -> BoxedSystem {
-        let system = asset_render_resources_node_system::<T>
+        let system = asset_render_resources_node_system::<T>.config(|config| {
-            .system()
+            config.0 = Some(RenderResourcesNodeState {
-            .config(|config| {
+                command_queue: self.command_queue.clone(),
-                config.0 = Some(RenderResourcesNodeState {
+                uniform_buffer_arrays: UniformBufferArrays::<HandleId, T>::default(),
-                    command_queue: self.command_queue.clone(),
+                dynamic_uniforms: self.dynamic_uniforms,
-                    uniform_buffer_arrays: UniformBufferArrays::<HandleId, T>::default(),
+            })
-                    dynamic_uniforms: self.dynamic_uniforms,
+        });
-                })
-            });
 
         Box::new(system)
     }
@@ -621,8 +620,8 @@ fn asset_render_resources_node_system<T: RenderResources + Asset>(
     render_resource_context: Res<Box<dyn RenderResourceContext>>,
     removed_handles: RemovedComponents<Handle<T>>,
     mut queries: QuerySet<(
-        Query<(&Handle<T>, &mut RenderPipelines), Changed<Handle<T>>>,
+        QueryState<(&Handle<T>, &mut RenderPipelines), Changed<Handle<T>>>,
-        Query<&mut RenderPipelines, With<Handle<T>>>,
+        QueryState<&mut RenderPipelines, With<Handle<T>>>,
     )>,
 ) {
     let state = state.deref_mut();
@@ -752,7 +751,7 @@ fn asset_render_resources_node_system<T: RenderResources + Asset>(
 
     // update removed entity asset mapping
     for entity in removed_handles.iter() {
-        if let Ok(mut render_pipelines) = queries.q1_mut().get_mut(entity) {
+        if let Ok(mut render_pipelines) = queries.q1().get_mut(entity) {
             render_pipelines
                 .bindings
                 .remove_asset_with_type(TypeId::of::<T>())
@@ -760,7 +759,7 @@ fn asset_render_resources_node_system<T: RenderResources + Asset>(
     }
 
     // update changed entity asset mapping
-    for (asset_handle, mut render_pipelines) in queries.q0_mut().iter_mut() {
+    for (asset_handle, mut render_pipelines) in queries.q0().iter_mut() {
         render_pipelines
             .bindings
             .remove_asset_with_type(TypeId::of::<T>());

crates/bevy_render/src/shader/shader_reflect.rs

@@ -151,7 +151,19 @@ fn reflect_binding(
                 filtering: true,
             },
         ),
-        _ => panic!("Unsupported bind type {:?}.", binding.descriptor_type),
+        _ => {
+            let ReflectDescriptorBinding {
+                descriptor_type,
+                name,
+                set,
+                binding,
+                ..
+            } = binding;
+            panic!(
+                "Unsupported shader bind type {:?} (name '{}', set {}, binding {})",
+                descriptor_type, name, set, binding
+            );
+        }
     };
 
     let shader_stage = match shader_stage {

crates/bevy_render/src/wireframe/mod.rs

@@ -8,9 +8,9 @@ use crate::{
 use bevy_app::prelude::*;
 use bevy_asset::{Assets, Handle, HandleUntyped};
 use bevy_ecs::{
-    query::With,
+    query::{QueryState, With},
     reflect::ReflectComponent,
-    system::{IntoSystem, Query, QuerySet, Res},
+    system::{QuerySet, Res},
     world::Mut,
 };
 use bevy_reflect::{Reflect, TypeUuid};
@@ -27,7 +27,7 @@ pub struct WireframePlugin;
 impl Plugin for WireframePlugin {
     fn build(&self, app: &mut App) {
         app.init_resource::<WireframeConfig>()
-            .add_system_to_stage(crate::RenderStage::Draw, draw_wireframes_system.system());
+            .add_system_to_stage(crate::RenderStage::Draw, draw_wireframes_system);
         let world = app.world.cell();
         let mut shaders = world.get_resource_mut::<Assets<Shader>>().unwrap();
         let mut pipelines = world
@@ -62,8 +62,8 @@ pub fn draw_wireframes_system(
     meshes: Res<Assets<Mesh>>,
     wireframe_config: Res<WireframeConfig>,
     mut query: QuerySet<(
-        Query<(&mut Draw, &mut RenderPipelines, &Handle<Mesh>, &Visible)>,
+        QueryState<(&mut Draw, &mut RenderPipelines, &Handle<Mesh>, &Visible)>,
-        Query<(&mut Draw, &mut RenderPipelines, &Handle<Mesh>, &Visible), With<Wireframe>>,
+        QueryState<(&mut Draw, &mut RenderPipelines, &Handle<Mesh>, &Visible), With<Wireframe>>,
     )>,
 ) {
     let iterator = |(mut draw, mut render_pipelines, mesh_handle, visible): (
@@ -123,8 +123,8 @@ pub fn draw_wireframes_system(
     };
 
     if wireframe_config.global {
-        query.q0_mut().iter_mut().for_each(iterator);
+        query.q0().iter_mut().for_each(iterator);
     } else {
-        query.q1_mut().iter_mut().for_each(iterator);
+        query.q1().iter_mut().for_each(iterator);
     }
 }

crates/bevy_text/Cargo.toml

@@ -2,10 +2,6 @@
 name = "bevy_text"
 version = "0.5.0"
 edition = "2018"
-authors = [
-    "Bevy Contributors <bevyengine@gmail.com>",
-    "Carter Anderson <mcanders1@gmail.com>",
-]
 description = "Provides text functionality for Bevy Engine"
 homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"

crates/bevy_text/src/lib.rs

@@ -29,7 +29,7 @@ pub mod prelude {
 
 use bevy_app::prelude::*;
 use bevy_asset::AddAsset;
-use bevy_ecs::{entity::Entity, system::IntoSystem};
+use bevy_ecs::entity::Entity;
 use bevy_render::RenderStage;
 
 pub type DefaultTextPipeline = TextPipeline<Entity>;
@@ -43,7 +43,7 @@ impl Plugin for TextPlugin {
             .add_asset::<FontAtlasSet>()
             .init_asset_loader::<FontLoader>()
             .insert_resource(DefaultTextPipeline::default())
-            .add_system_to_stage(CoreStage::PostUpdate, text2d_system.system())
+            .add_system_to_stage(CoreStage::PostUpdate, text2d_system)
-            .add_system_to_stage(RenderStage::Draw, text2d::draw_text2d_system.system());
+            .add_system_to_stage(RenderStage::Draw, text2d::draw_text2d_system);
     }
 }

crates/bevy_text/src/text2d.rs

@@ -2,7 +2,7 @@ use bevy_asset::Assets;
 use bevy_ecs::{
     bundle::Bundle,
     entity::Entity,
-    query::{Changed, With, Without},
+    query::{Changed, QueryState, With, Without},
     system::{Local, Query, QuerySet, Res, ResMut},
 };
 use bevy_math::{Size, Vec3};
@@ -136,12 +136,12 @@ pub fn text2d_system(
     mut font_atlas_set_storage: ResMut<Assets<FontAtlasSet>>,
     mut text_pipeline: ResMut<DefaultTextPipeline>,
     mut text_queries: QuerySet<(
-        Query<Entity, (With<MainPass>, Changed<Text>)>,
+        QueryState<Entity, (With<MainPass>, Changed<Text>)>,
-        Query<(&Text, &mut Text2dSize), With<MainPass>>,
+        QueryState<(&Text, &mut Text2dSize), With<MainPass>>,
     )>,
 ) {
     // Adds all entities where the text or the style has changed to the local queue
-    for entity in text_queries.q0_mut().iter_mut() {
+    for entity in text_queries.q0().iter_mut() {
         queued_text.entities.push(entity);
     }
 
@@ -157,7 +157,7 @@ pub fn text2d_system(
 
     // Computes all text in the local queue
     let mut new_queue = Vec::new();
-    let query = text_queries.q1_mut();
+    let mut query = text_queries.q1();
     for entity in queued_text.entities.drain(..) {
         if let Ok((text, mut calculated_size)) = query.get_mut(entity) {
             match text_pipeline.queue_text(

crates/bevy_ui/Cargo.toml

@@ -2,10 +2,6 @@
 name = "bevy_ui"
 version = "0.5.0"
 edition = "2018"
-authors = [
-    "Bevy Contributors <bevyengine@gmail.com>",
-    "Carter Anderson <mcanders1@gmail.com>",
-]
 description = "A custom ECS-driven UI framework built specifically for Bevy Engine"
 homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"

crates/bevy_ui/src/flex/convert.rs

@@ -114,8 +114,8 @@ impl From<Direction> for stretch::style::Direction {
     fn from(value: Direction) -> Self {
         match value {
             Direction::Inherit => stretch::style::Direction::Inherit,
-            Direction::Ltr => stretch::style::Direction::LTR,
+            Direction::LeftToRight => stretch::style::Direction::LTR,
-            Direction::Rtl => stretch::style::Direction::RTL,
+            Direction::RightToLeft => stretch::style::Direction::RTL,
         }
     }
 }

crates/bevy_ui/src/lib.rs

@@ -22,10 +22,7 @@ pub mod prelude {
 }
 
 use bevy_app::prelude::*;
-use bevy_ecs::{
+use bevy_ecs::schedule::{ParallelSystemDescriptorCoercion, SystemLabel};
-    schedule::{ParallelSystemDescriptorCoercion, SystemLabel},
-    system::IntoSystem,
-};
 use bevy_input::InputSystem;
 use bevy_math::{Rect, Size};
 use bevy_render::RenderStage;
@@ -62,35 +59,30 @@ impl Plugin for UiPlugin {
             .register_type::<Val>()
             .add_system_to_stage(
                 CoreStage::PreUpdate,
-                ui_focus_system
+                ui_focus_system.label(UiSystem::Focus).after(InputSystem),
-                    .system()
-                    .label(UiSystem::Focus)
-                    .after(InputSystem),
             )
             // add these stages to front because these must run before transform update systems
             .add_system_to_stage(
                 CoreStage::PostUpdate,
-                widget::text_system.system().before(UiSystem::Flex),
+                widget::text_system.before(UiSystem::Flex),
             )
             .add_system_to_stage(
                 CoreStage::PostUpdate,
-                widget::image_node_system.system().before(UiSystem::Flex),
+                widget::image_node_system.before(UiSystem::Flex),
             )
             .add_system_to_stage(
                 CoreStage::PostUpdate,
                 flex_node_system
-                    .system()
                     .label(UiSystem::Flex)
                     .before(TransformSystem::TransformPropagate),
             )
             .add_system_to_stage(
                 CoreStage::PostUpdate,
                 ui_z_system
-                    .system()
                     .after(UiSystem::Flex)
                     .before(TransformSystem::TransformPropagate),
             )
-            .add_system_to_stage(RenderStage::Draw, widget::draw_text_system.system());
+            .add_system_to_stage(RenderStage::Draw, widget::draw_text_system);
 
         crate::render::add_ui_graph(&mut app.world);
     }

crates/bevy_ui/src/ui_node.rs

@@ -155,8 +155,8 @@ impl Default for AlignContent {
 #[reflect_value(PartialEq, Serialize, Deserialize)]
 pub enum Direction {
     Inherit,
-    Ltr,
+    LeftToRight,
-    Rtl,
+    RightToLeft,
 }
 
 impl Default for Direction {

crates/bevy_ui/src/update.rs

@@ -54,7 +54,7 @@ fn update_hierarchy(
 mod tests {
     use bevy_ecs::{
         schedule::{Schedule, Stage, SystemStage},
-        system::{CommandQueue, Commands, IntoSystem},
+        system::{CommandQueue, Commands},
         world::World,
     };
     use bevy_transform::{components::Transform, hierarchy::BuildChildren};
@@ -122,7 +122,7 @@ mod tests {
 
         let mut schedule = Schedule::default();
         let mut update_stage = SystemStage::parallel();
-        update_stage.add_system(ui_z_system.system());
+        update_stage.add_system(ui_z_system);
         schedule.add_stage("update", update_stage);
         schedule.run(&mut world);
 

crates/bevy_ui/src/widget/text.rs

@@ -2,7 +2,7 @@ use crate::{CalculatedSize, Node, Style, Val};
 use bevy_asset::Assets;
 use bevy_ecs::{
     entity::Entity,
-    query::{Changed, Or, With, Without},
+    query::{Changed, Or, QueryState, With, Without},
     system::{Local, Query, QuerySet, Res, ResMut},
 };
 use bevy_math::Size;
@@ -53,9 +53,9 @@ pub fn text_system(
     mut font_atlas_set_storage: ResMut<Assets<FontAtlasSet>>,
     mut text_pipeline: ResMut<DefaultTextPipeline>,
     mut text_queries: QuerySet<(
-        Query<Entity, Or<(Changed<Text>, Changed<Style>)>>,
+        QueryState<Entity, Or<(Changed<Text>, Changed<Style>)>>,
-        Query<Entity, (With<Text>, With<Style>)>,
+        QueryState<Entity, (With<Text>, With<Style>)>,
-        Query<(&Text, &Style, &mut CalculatedSize)>,
+        QueryState<(&Text, &Style, &mut CalculatedSize)>,
     )>,
 ) {
     let scale_factor = if let Some(window) = windows.get_primary() {
@@ -86,7 +86,7 @@ pub fn text_system(
 
     // Computes all text in the local queue
     let mut new_queue = Vec::new();
-    let query = text_queries.q2_mut();
+    let mut query = text_queries.q2();
     for entity in queued_text.entities.drain(..) {
         if let Ok((text, style, mut calculated_size)) = query.get_mut(entity) {
             let node_size = Size::new(

examples/2d/many_sprites.rs

@@ -2,6 +2,7 @@ use bevy::{
     diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
     math::Quat,
     prelude::*,
+    render::camera::Camera,
     sprite::SpriteSettings,
 };
 
@@ -9,9 +10,6 @@ use rand::Rng;
 
 const CAMERA_SPEED: f32 = 1000.0;
 
-pub struct PrintTimer(Timer);
-pub struct Position(Transform);
-
 /// This example is for performance testing purposes.
 /// See https://github.com/bevyengine/bevy/pull/1492
 fn main() {
@@ -24,8 +22,8 @@ fn main() {
         })
         .add_plugins(DefaultPlugins)
         .add_startup_system(setup)
-        .add_system(tick.system().label("Tick"))
+        .add_system(tick_system.label("Tick"))
-        .add_system(move_camera.system().after("Tick"))
+        .add_system(move_camera_system.after("Tick"))
         .run()
 }
 
@@ -44,14 +42,15 @@ fn setup(
 
     let sprite_handle = materials.add(assets.load("branding/icon.png").into());
 
+    // Spawns the camera
     commands
         .spawn()
         .insert_bundle(OrthographicCameraBundle::new_2d())
-        .insert(PrintTimer(Timer::from_seconds(1.0, true)))
+        .insert(Timer::from_seconds(1.0, true))
-        .insert(Position(Transform::from_translation(Vec3::new(
+        .insert(Transform::from_xyz(0.0, 0.0, 1000.0));
-            0.0, 0.0, 1000.0,
-        ))));
 
+    // Builds and spawns the sprites
+    let mut sprites = vec![];
     for y in -half_y..half_y {
         for x in -half_x..half_x {
             let position = Vec2::new(x as f32, y as f32);
@@ -59,7 +58,7 @@ fn setup(
             let rotation = Quat::from_rotation_z(rng.gen::<f32>());
             let scale = Vec3::splat(rng.gen::<f32>() * 2.0);
 
-            commands.spawn().insert_bundle(SpriteBundle {
+            sprites.push(SpriteBundle {
                 material: sprite_handle.clone(),
                 transform: Transform {
                     translation,
@@ -71,26 +70,23 @@ fn setup(
             });
         }
     }
+    commands.spawn_batch(sprites);
 }
 
-fn move_camera(time: Res<Time>, mut query: Query<(&mut Transform, &mut Position)>) {
+// System for rotating and translating the camera
-    for (mut transform, mut position) in query.iter_mut() {
+fn move_camera_system(time: Res<Time>, mut camera_query: Query<&mut Transform, With<Camera>>) {
-        position
+    let mut camera_transform = camera_query.single_mut();
-            .0
+    camera_transform.rotate(Quat::from_rotation_z(time.delta_seconds() * 0.5));
-            .rotate(Quat::from_rotation_z(time.delta_seconds() * 0.5));
+    *camera_transform = *camera_transform
-        position.0 =
+        * Transform::from_translation(Vec3::X * CAMERA_SPEED * time.delta_seconds());
-            position.0 * Transform::from_translation(Vec3::X * CAMERA_SPEED * time.delta_seconds());
+}
-        transform.translation = position.0.translation;
+
-        transform.rotation *= Quat::from_rotation_z(time.delta_seconds() / 2.0);
+// System for printing the number of sprites on every tick of the timer
-    }
+fn tick_system(time: Res<Time>, sprites_query: Query<&Sprite>, mut timer_query: Query<&mut Timer>) {
-}
+    let mut timer = timer_query.single_mut();
-
+    timer.tick(time.delta());
-fn tick(time: Res<Time>, sprites: Query<&Sprite>, mut query: Query<&mut PrintTimer>) {
+
-    for mut timer in query.iter_mut() {
+    if timer.just_finished() {
-        timer.0.tick(time.delta());
+        info!("Sprites: {}", sprites_query.iter().count(),);
-
-        if timer.0.just_finished() {
-            info!("Sprites: {}", sprites.iter().count(),);
-        }
     }
 }

examples/2d/sprite.rs

@@ -9,13 +9,13 @@ fn main() {
 
 fn setup(
     mut commands: Commands,
-    _asset_server: Res<AssetServer>,
+    asset_server: Res<AssetServer>,
-    // mut materials: ResMut<Assets<ColorMaterial>>,
+    mut materials: ResMut<Assets<ColorMaterial>>,
 ) {
-    // let texture_handle = asset_server.load("branding/icon.png");
+    let texture_handle = asset_server.load("branding/icon.png");
     commands.spawn_bundle(OrthographicCameraBundle::new_2d());
     commands.spawn_bundle(SpriteBundle {
-        // material: materials.add(texture_handle.into()),
+        material: materials.add(texture_handle.into()),
         ..Default::default()
     });
 }

examples/3d/3d_scene.rs

@@ -4,7 +4,7 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/3d/load_gltf.rs

@@ -8,8 +8,8 @@ fn main() {
         })
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(rotator_system.system())
+        .add_system(rotator_system)
         .run();
 }
 

examples/3d/msaa.rs

@@ -8,7 +8,7 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/3d/orthographic.rs

@@ -4,7 +4,7 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/3d/parenting.rs

@@ -6,8 +6,8 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(rotator_system.system())
+        .add_system(rotator_system)
         .run();
 }
 

examples/3d/pbr.rs

@@ -5,7 +5,7 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/3d/render_to_texture.rs

@@ -226,8 +226,8 @@ fn setup(
 fn main() {
     let mut app = App::new();
     app.add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(cube_rotator_system.system())
+        .add_system(cube_rotator_system)
-        .add_system(rotator_system.system())
+        .add_system(rotator_system)
         .run();
 }

examples/3d/shadow_caster_receiver_pipelined.rs

@@ -154,11 +154,11 @@ fn toggle_light(
 fn toggle_shadows(
     mut commands: Commands,
     input: Res<Input<KeyCode>>,
-    queries: QuerySet<(
+    mut queries: QuerySet<(
-        Query<Entity, (With<Handle<Mesh>>, With<NotShadowCaster>)>,
+        QueryState<Entity, (With<Handle<Mesh>>, With<NotShadowCaster>)>,
-        Query<Entity, (With<Handle<Mesh>>, With<NotShadowReceiver>)>,
+        QueryState<Entity, (With<Handle<Mesh>>, With<NotShadowReceiver>)>,
-        Query<Entity, (With<Handle<Mesh>>, Without<NotShadowCaster>)>,
+        QueryState<Entity, (With<Handle<Mesh>>, Without<NotShadowCaster>)>,
-        Query<Entity, (With<Handle<Mesh>>, Without<NotShadowReceiver>)>,
+        QueryState<Entity, (With<Handle<Mesh>>, Without<NotShadowReceiver>)>,
     )>,
 ) {
     if input.just_pressed(KeyCode::C) {

examples/3d/spawner.rs

@@ -17,8 +17,8 @@ fn main() {
         .add_plugins(DefaultPlugins)
         .add_plugin(FrameTimeDiagnosticsPlugin::default())
         .add_plugin(LogDiagnosticsPlugin::default())
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(move_cubes.system())
+        .add_system(move_cubes)
         .run();
 }
 

examples/3d/texture.rs

@@ -4,7 +4,7 @@ use bevy::prelude::*;
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/3d/update_gltf_scene.rs

@@ -4,10 +4,10 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .insert_resource(SceneInstance::default())
+        .init_resource::<SceneInstance>()
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(scene_update.system())
+        .add_system(scene_update)
-        .add_system(move_scene_entities.system())
+        .add_system(move_scene_entities)
         .run();
 }
 

examples/3d/wireframe.rs

@@ -16,7 +16,7 @@ fn main() {
         })
         .add_plugins(DefaultPlugins)
         .add_plugin(WireframePlugin)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/3d/z_sort_debug.rs

@@ -11,9 +11,9 @@ use bevy::{
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(rotator_system.system())
+        .add_system(rotator_system)
-        .add_system(camera_order_color_system.system())
+        .add_system(camera_order_color_system)
         .run();
 }
 

examples/README.md

@@ -171,7 +171,6 @@ Example | File | Description
 `hierarchy` | [`ecs/hierarchy.rs`](./ecs/hierarchy.rs) | Creates a hierarchy of parents and children entities
 `iter_combinations` | [`ecs/iter_combinations.rs`](./ecs/iter_combinations.rs) | Shows how to iterate over combinations of query results.
 `parallel_query` | [`ecs/parallel_query.rs`](./ecs/parallel_query.rs) | Illustrates parallel queries with `ParallelIterator`
-`query_bundle` | [`ecs/query_bundle.rs`](./ecs/query_bundle.rs) | Shows how to query entities that contain components in a `Bundle`
 `removal_detection` | [`ecs/removal_detection.rs`](./ecs/removal_detection.rs) | Query for entities that had a specific component removed in a previous stage during the current frame.
 `startup_system` | [`ecs/startup_system.rs`](./ecs/startup_system.rs) | Demonstrates a startup system (one that runs once when the app starts up)
 `state` | [`ecs/state.rs`](./ecs/state.rs) | Illustrates how to use States to control transitioning from a Menu state to an InGame state

examples/android/android.rs

@@ -6,7 +6,7 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 2 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/app/custom_loop.rs

@@ -24,6 +24,6 @@ fn main() {
     App::new()
         .insert_resource(Input(String::new()))
         .set_runner(my_runner)
-        .add_system(print_system.system())
+        .add_system(print_system)
         .run();
 }

examples/app/drag_and_drop.rs

@@ -3,7 +3,7 @@ use bevy::prelude::*;
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_system(file_drag_and_drop_system.system())
+        .add_system(file_drag_and_drop_system)
         .run();
 }
 

examples/app/headless.rs

@@ -13,7 +13,7 @@ fn main() {
     App::new()
         .insert_resource(ScheduleRunnerSettings::run_once())
         .add_plugins(MinimalPlugins)
-        .add_system(hello_world_system.system())
+        .add_system(hello_world_system)
         .run();
 
     // this app loops forever at 60 fps
@@ -22,7 +22,7 @@ fn main() {
             1.0 / 60.0,
         )))
         .add_plugins(MinimalPlugins)
-        .add_system(counter.system())
+        .add_system(counter)
         .run();
 }
 

examples/app/logs.rs

@@ -9,7 +9,7 @@ fn main() {
         //     filter: "wgpu=warn,bevy_ecs=info".to_string(),
         // })
         .add_plugins(DefaultPlugins)
-        .add_system(log_system.system())
+        .add_system(log_system)
         .run();
 }
 

examples/app/plugin.rs

@@ -28,8 +28,7 @@ impl Plugin for PrintMessagePlugin {
             message: self.message.clone(),
             timer: Timer::new(self.wait_duration, true),
         };
-        app.insert_resource(state)
+        app.insert_resource(state).add_system(print_message_system);
-            .add_system(print_message_system.system());
     }
 }
 

examples/app/plugin_group.rs

@@ -29,7 +29,7 @@ pub struct PrintHelloPlugin;
 
 impl Plugin for PrintHelloPlugin {
     fn build(&self, app: &mut App) {
-        app.add_system(print_hello_system.system());
+        app.add_system(print_hello_system);
     }
 }
 
@@ -41,7 +41,7 @@ pub struct PrintWorldPlugin;
 
 impl Plugin for PrintWorldPlugin {
     fn build(&self, app: &mut App) {
-        app.add_system(print_world_system.system());
+        app.add_system(print_world_system);
     }
 }
 

examples/app/return_after_run.rs

@@ -8,7 +8,7 @@ fn main() {
         })
         .insert_resource(ClearColor(Color::rgb(0.2, 0.2, 0.8)))
         .add_plugins(DefaultPlugins)
-        .add_system(system1.system())
+        .add_system(system1)
         .run();
     println!("Running another App.");
     App::new()
@@ -19,7 +19,7 @@ fn main() {
         .add_plugins_with(DefaultPlugins, |group| {
             group.disable::<bevy::log::LogPlugin>()
         })
-        .add_system(system2.system())
+        .add_system(system2)
         .run();
     println!("Done.");
 }

examples/asset/asset_loading.rs

@@ -5,7 +5,7 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/asset/custom_asset.rs

@@ -39,8 +39,8 @@ fn main() {
         .init_resource::<State>()
         .add_asset::<CustomAsset>()
         .init_asset_loader::<CustomAssetLoader>()
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(print_on_load.system())
+        .add_system(print_on_load)
         .run();
 }
 

examples/asset/custom_asset_io.rs

@@ -85,7 +85,7 @@ fn main() {
             // asset system are initialized correctly.
             group.add_before::<bevy::asset::AssetPlugin, _>(CustomAssetIoPlugin)
         })
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/asset/hot_asset_reloading.rs

@@ -6,7 +6,7 @@ use bevy::prelude::*;
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/async_tasks/async_compute.rs

@@ -12,10 +12,10 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup_env.system())
+        .add_startup_system(setup_env)
-        .add_startup_system(add_assets.system())
+        .add_startup_system(add_assets)
-        .add_startup_system(spawn_tasks.system())
+        .add_startup_system(spawn_tasks)
-        .add_system(handle_tasks.system())
+        .add_system(handle_tasks)
         .run();
 }
 

examples/audio/audio.rs

@@ -4,7 +4,7 @@ use bevy::prelude::*;
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
         .run();
 }
 

examples/diagnostics/custom_diagnostic.rs

@@ -10,8 +10,8 @@ fn main() {
         // The "print diagnostics" plugin is optional. It just visualizes our diagnostics in the
         // console
         .add_plugin(LogDiagnosticsPlugin::default())
-        .add_startup_system(setup_diagnostic_system.system())
+        .add_startup_system(setup_diagnostic_system)
-        .add_system(my_system.system())
+        .add_system(my_system)
         .run();
 }
 

examples/ecs/component_change_detection.rs

@@ -5,10 +5,10 @@ use rand::Rng;
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(change_component.system())
+        .add_system(change_component)
-        .add_system(change_detection.system())
+        .add_system(change_detection)
-        .add_system(tracker_monitoring.system())
+        .add_system(tracker_monitoring)
         .run();
 }
 

examples/ecs/ecs_guide.rs

@@ -272,7 +272,7 @@ fn main() {
         // that :) The plugin below runs our app's "system schedule" once every 5 seconds
         // (configured above).
         .add_plugin(ScheduleRunnerPlugin::default())
-        // Resources that implement the Default or FromResources trait can be added like this:
+        // Resources that implement the Default or FromWorld trait can be added like this:
         .init_resource::<GameState>()
         // Startup systems run exactly once BEFORE all other systems. These are generally used for
         // app initialization code (ex: adding entities and resources)

examples/ecs/event.rs

@@ -7,8 +7,8 @@ fn main() {
         .add_plugins(DefaultPlugins)
         .add_event::<MyEvent>()
         .init_resource::<EventTriggerState>()
-        .add_system(event_trigger_system.system())
+        .add_system(event_trigger_system)
-        .add_system(event_listener_system.system())
+        .add_system(event_listener_system)
         .run();
 }
 

examples/ecs/fixed_timestep.rs

@@ -12,7 +12,7 @@ fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
         // this system will run once every update (it should match your screen's refresh rate)
-        .add_system(frame_update.system())
+        .add_system(frame_update)
         // add a new stage that runs twice a second
         .add_stage_after(
             CoreStage::Update,
@@ -24,7 +24,7 @@ fn main() {
                         // FixedTimestep state from within a system
                         .with_label(LABEL),
                 )
-                .with_system(fixed_update.system()),
+                .with_system(fixed_update),
         )
         .run();
 }

examples/ecs/hierarchy.rs

@@ -3,8 +3,8 @@ use bevy::prelude::*;
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_startup_system(setup.system())
+        .add_startup_system(setup)
-        .add_system(rotate.system())
+        .add_system(rotate)
         .run();
 }
 

examples/ecs/iter_combinations.rs

@@ -10,14 +10,14 @@ fn main() {
     App::new()
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
-        .add_startup_system(generate_bodies.system())
+        .add_startup_system(generate_bodies)
         .add_stage_after(
             CoreStage::Update,
             FixedUpdateStage,
             SystemStage::parallel()
                 .with_run_criteria(FixedTimestep::step(DELTA_TIME))
-                .with_system(interact_bodies.system())
+                .with_system(interact_bodies)
-                .with_system(integrate.system()),
+                .with_system(integrate),
         )
         .run();
 }

examples/ecs/parallel_query.rs

@@ -70,8 +70,8 @@ fn bounce_system(
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
-        .add_startup_system(spawn_system.system())
+        .add_startup_system(spawn_system)
-        .add_system(move_system.system())
+        .add_system(move_system)
-        .add_system(bounce_system.system())
+        .add_system(bounce_system)
         .run();
 }