Cleanup FromResources (#2601)

## Objective

- Clean up remaining references to the trait `FromResources`, which was replaced in favor of `FromWorld` during the ECS rework.

## Solution

- Remove the derive macro for `FromResources`
- Change doc references of `FromResources` to `FromWorld`

(this is the first item in #2576)

crates/bevy_app/src/app.rs

@@ -343,7 +343,7 @@ impl App {
     /// A resource in Bevy represents globally unique data. Resources must be added to Bevy Apps
     /// before using them. This happens with [`App::insert_resource`].
     ///
-    /// See also `init_resource` for resources that implement `Default` or [`FromResources`].
+    /// See also `init_resource` for resources that implement `Default` or [`FromWorld`].
     ///
     /// ## Example
     /// ```
@@ -390,7 +390,7 @@ impl App {
 
     /// Initialize a resource in the current [App], if it does not exist yet
     ///
-    /// Adds a resource that implements `Default` or [`FromResources`] trait.
+    /// Adds a resource that implements `Default` or [`FromWorld`] trait.
     /// If the resource already exists, `init_resource` does nothing.
     ///
     /// ## Example

crates/bevy_derive/src/lib.rs

@@ -7,18 +7,10 @@ mod enum_variant_meta;
 mod modules;
 mod render_resource;
 mod render_resources;
-mod resource;
 mod shader_defs;
 
 use proc_macro::TokenStream;
 
-/// Derives the FromResources trait. Each field must also implement the FromResources trait or this
-/// will fail. FromResources is automatically implemented for types that implement Default.
-#[proc_macro_derive(FromResources)]
-pub fn derive_from_resources(input: TokenStream) -> TokenStream {
-    resource::derive_from_resources(input)
-}
-
 /// Derives the Bytes trait. Each field must also implements Bytes or this will fail.
 #[proc_macro_derive(Bytes)]
 pub fn derive_bytes(input: TokenStream) -> TokenStream {

crates/bevy_derive/src/modules.rs

@@ -1,4 +1,3 @@
-pub const BEVY_APP: &str = "bevy_app";
 pub const BEVY_ASSET: &str = "bevy_asset";
 pub const BEVY_CORE: &str = "bevy_core";
 pub const BEVY_RENDER: &str = "bevy_render";

crates/bevy_derive/src/resource.rs

@@ -1,33 +0,0 @@
-use bevy_macro_utils::BevyManifest;
-use proc_macro::TokenStream;
-use quote::quote;
-use syn::{parse_macro_input, Data, DataStruct, DeriveInput, Fields};
-
-pub fn derive_from_resources(input: TokenStream) -> TokenStream {
-    let ast = parse_macro_input!(input as DeriveInput);
-    let fields = match &ast.data {
-        Data::Struct(DataStruct {
-            fields: Fields::Named(fields),
-            ..
-        }) => &fields.named,
-        _ => panic!("Expected a struct with named fields."),
-    };
-
-    let bevy_app_path = BevyManifest::default().get_path(crate::modules::BEVY_APP);
-    let field_types = fields.iter().map(|field| &field.ty);
-    let fields = fields.iter().map(|field| field.ident.as_ref().unwrap());
-    let generics = ast.generics;
-    let (impl_generics, ty_generics, _where_clause) = generics.split_for_impl();
-    let struct_name = &ast.ident;
-
-    TokenStream::from(quote! {
-        impl #impl_generics #bevy_app_path::FromResources for #struct_name#ty_generics {
-            fn from_resources(resources: &Resources) -> Self {
-                use #bevy_app_path::FromResources;
-                #struct_name {
-                    #(#fields: <#field_types>::from_resources(resources),)*
-                }
-            }
-        }
-    })
-}

crates/bevy_transform/src/components/parent.rs

@@ -52,7 +52,7 @@ impl MapEntities for PreviousParent {
     }
 }
 
-// TODO: Better handle this case see `impl FromResources for Parent`
+// TODO: Better handle this case see `impl FromWorld for Parent`
 impl FromWorld for PreviousParent {
     fn from_world(_world: &mut World) -> Self {
         PreviousParent(Entity::new(u32::MAX))

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/scene/scene.rs

@@ -13,12 +13,12 @@ fn main() {
         .run();
 }
 
-// Registered components must implement the `Reflect` and `FromResources` traits.
+// Registered components must implement the `Reflect` and `FromWorld` traits.
 // The `Reflect` trait enables serialization, deserialization, and dynamic property access.
 // `Reflect` enable a bunch of cool behaviors, so its worth checking out the dedicated `reflect.rs`
-// example. The `FromResources` trait determines how your component is constructed when it loads.
+// example. The `FromWorld` trait determines how your component is constructed when it loads.
 // For simple use cases you can just implement the `Default` trait (which automatically implements
-// FromResources). The simplest registered component just needs these two derives:
+// FromWorld). The simplest registered component just needs these two derives:
 #[derive(Reflect, Default)]
 #[reflect(Component)] // this tells the reflect derive to also reflect component behaviors
 struct ComponentA {
@@ -27,8 +27,8 @@ struct ComponentA {
 }
 
 // Some components have fields that cannot (or should not) be written to scene files. These can be
-// ignored with the #[reflect(ignore)] attribute. This is also generally where the `FromResources`
-// trait comes into play. `FromResources` gives you access to your App's current ECS `Resources`
+// ignored with the #[reflect(ignore)] attribute. This is also generally where the `FromWorld`
+// trait comes into play. `FromWorld` gives you access to your App's current ECS `Resources`
 // when you construct your component.
 #[derive(Reflect)]
 #[reflect(Component)]