Reflect auto registration

Cargo.toml

@@ -130,6 +130,7 @@ default = [
   "hdr",
   "multi_threaded",
   "png",
+  "reflect_auto_register",
   "smaa_luts",
   "sysinfo_plugin",
   "tonemapping_luts",
@@ -454,6 +455,9 @@ track_change_detection = ["bevy_internal/track_change_detection"]
 # Enable function reflection
 reflect_functions = ["bevy_internal/reflect_functions"]
 
+# Enable automatic reflect registration
+reflect_auto_register = ["bevy_internal/reflect_auto_register"]
+
 # Enable winit custom cursor support
 custom_cursor = ["bevy_internal/custom_cursor"]
 

crates/bevy_app/Cargo.toml

@@ -18,6 +18,11 @@ reflect_functions = [
   "bevy_reflect/functions",
   "bevy_ecs/reflect_functions",
 ]
+reflect_auto_register = [
+  "bevy_reflect",
+  "bevy_reflect/auto_register",
+  "bevy_ecs/reflect_auto_register",
+]
 
 [dependencies]
 # bevy

crates/bevy_app/src/app.rs

@@ -91,9 +91,12 @@ impl Default for App {
         let mut app = App::empty();
         app.sub_apps.main.update_schedule = Some(Main.intern());
 
-        #[cfg(feature = "bevy_reflect")]
+        #[cfg(all(feature = "bevy_reflect", not(feature = "reflect_auto_register")))]
         app.init_resource::<AppTypeRegistry>();
 
+        #[cfg(feature = "reflect_auto_register")]
+        app.insert_resource(AppTypeRegistry::new_with_derived_types());
+
         #[cfg(feature = "reflect_functions")]
         app.init_resource::<AppFunctionRegistry>();
 

crates/bevy_ecs/Cargo.toml

@@ -18,6 +18,7 @@ bevy_debug_stepping = []
 serialize = ["dep:serde"]
 track_change_detection = []
 reflect_functions = ["bevy_reflect", "bevy_reflect/functions"]
+reflect_auto_register = ["bevy_reflect", "bevy_reflect/auto_register"]
 detailed_trace = []
 
 [dependencies]

crates/bevy_ecs/src/reflect/mod.rs

@@ -49,6 +49,18 @@ impl DerefMut for AppTypeRegistry {
     }
 }
 
+impl AppTypeRegistry {
+    /// Creates [`AppTypeRegistry`] and automatically registers all types deriving [`Reflect`].
+    ///
+    /// See [`TypeRegistry::register_derived_types`] for more details.
+    #[cfg(feature = "reflect_auto_register")]
+    pub fn new_with_derived_types() -> Self {
+        let app_registry = AppTypeRegistry::default();
+        app_registry.write().register_derived_types();
+        app_registry
+    }
+}
+
 /// A [`Resource`] storing [`FunctionRegistry`] for
 /// function registrations relevant to a whole app.
 ///

crates/bevy_internal/Cargo.toml

@@ -250,6 +250,12 @@ reflect_functions = [
   "bevy_app/reflect_functions",
   "bevy_ecs/reflect_functions",
 ]
+# Enable automatic reflect registration
+reflect_auto_register = [
+  "bevy_reflect/auto_register",
+  "bevy_app/reflect_auto_register",
+  "bevy_ecs/reflect_auto_register",
+]
 
 # Enable winit custom cursor support
 custom_cursor = ["bevy_winit/custom_cursor"]

crates/bevy_reflect/Cargo.toml

@@ -26,6 +26,12 @@ debug_stack = []
 documentation = ["bevy_reflect_derive/documentation"]
 # Enables function reflection
 functions = ["bevy_reflect_derive/functions"]
+# Enables automatic reflect registration
+auto_register = [
+  "bevy_reflect_derive/auto_register",
+  "dep:inventory",
+  "dep:wasm-init",
+]
 alloc = []
 
 [dependencies]
@@ -53,6 +59,13 @@ smol_str = { version = "0.2.0", features = ["serde"], optional = true }
 uuid = { version = "1.0", optional = true, features = ["v4", "serde"] }
 wgpu-types = { version = "23", features = ["serde"], optional = true }
 
+# deps for automatic type registration
+[target.'cfg(not(target_family = "wasm"))'.dependencies]
+inventory = { version = "0.3", optional = true }
+[target.'cfg(target_family = "wasm")'.dependencies]
+wasm-init = { version = "0.2", optional = true }
+
+
 [dev-dependencies]
 ron = "0.8.0"
 rmp-serde = "1.1"

crates/bevy_reflect/derive/Cargo.toml

@@ -17,6 +17,8 @@ default = []
 documentation = []
 # Enables macro logic related to function reflection
 functions = []
+# Enables automatic reflect registration
+auto_register = []
 
 [dependencies]
 bevy_macro_utils = { path = "../../bevy_macro_utils", version = "0.15.0-dev" }

crates/bevy_reflect/derive/src/container_attributes.rs

@@ -24,6 +24,7 @@ mod kw {
     syn::custom_keyword!(PartialEq);
     syn::custom_keyword!(Hash);
     syn::custom_keyword!(no_field_bounds);
+    syn::custom_keyword!(no_auto_register);
     syn::custom_keyword!(opaque);
 }
 
@@ -188,6 +189,7 @@ pub(crate) struct ContainerAttributes {
     type_path_attrs: TypePathAttrs,
     custom_where: Option<WhereClause>,
     no_field_bounds: bool,
+    no_auto_register: bool,
     custom_attributes: CustomAttributes,
     is_opaque: bool,
     idents: Vec<Ident>,
@@ -242,6 +244,8 @@ impl ContainerAttributes {
             self.parse_opaque(input)
         } else if lookahead.peek(kw::no_field_bounds) {
             self.parse_no_field_bounds(input)
+        } else if lookahead.peek(kw::no_auto_register) {
+            self.parse_no_auto_register(input)
         } else if lookahead.peek(kw::Debug) {
             self.parse_debug(input)
         } else if lookahead.peek(kw::PartialEq) {
@@ -360,6 +364,16 @@ impl ContainerAttributes {
         Ok(())
     }
 
+    /// Parse `no_auto_register` attribute.
+    ///
+    /// Examples:
+    /// - `#[reflect(no_auto_register)]`
+    fn parse_no_auto_register(&mut self, input: ParseStream) -> syn::Result<()> {
+        input.parse::<kw::no_auto_register>()?;
+        self.no_auto_register = true;
+        Ok(())
+    }
+
     /// Parse `where` attribute.
     ///
     /// Examples:
@@ -543,6 +557,13 @@ impl ContainerAttributes {
         self.no_field_bounds
     }
 
+    /// Returns true if the `no_auto_register` attribute was found on this type.
+    // This is not feature-gated because derive macro shouldn't break if auto_register feature is disabled.
+    #[allow(dead_code)]
+    pub fn no_auto_register(&self) -> bool {
+        self.no_auto_register
+    }
+
     /// Returns true if the `opaque` attribute was found on this type.
     pub fn is_opaque(&self) -> bool {
         self.is_opaque

crates/bevy_reflect/derive/src/impls/common.rs

@@ -156,3 +156,28 @@ pub fn common_partial_reflect_methods(
         #debug_fn
     }
 }
+
+#[cfg(feature = "auto_register")]
+pub fn reflect_auto_registration(meta: &ReflectMeta) -> Option<proc_macro2::TokenStream> {
+    use quote::ToTokens;
+
+    if meta.attrs().no_auto_register() {
+        return None;
+    }
+
+    let bevy_reflect_path = meta.bevy_reflect_path();
+    let type_path = meta.type_path();
+    let generics = meta.type_path().generics();
+
+    if !generics.into_token_stream().is_empty() {
+        return None;
+    };
+
+    Some(quote! {
+        #bevy_reflect_path::__macro_exports::auto_register::auto_register_function!{
+            #bevy_reflect_path::__macro_exports::auto_register::AutomaticReflectRegistrations::add(
+                <#type_path as #bevy_reflect_path::__macro_exports::auto_register::RegisterForReflection>::__register
+            )
+        }
+    })
+}

crates/bevy_reflect/derive/src/impls/enums.rs

@@ -82,6 +82,11 @@ pub(crate) fn impl_enum(reflect_enum: &ReflectEnum) -> proc_macro2::TokenStream
     let (impl_generics, ty_generics, where_clause) =
         reflect_enum.meta().type_path().generics().split_for_impl();
 
+    #[cfg(not(feature = "auto_register"))]
+    let auto_register = None::<proc_macro2::TokenStream>;
+    #[cfg(feature = "auto_register")]
+    let auto_register = crate::impls::reflect_auto_registration(reflect_enum.meta());
+
     let where_reflect_clause = where_clause_options.extend_where_clause(where_clause);
 
     quote! {
@@ -95,6 +100,8 @@ pub(crate) fn impl_enum(reflect_enum: &ReflectEnum) -> proc_macro2::TokenStream
 
         #function_impls
 
+        #auto_register
+
         impl #impl_generics #bevy_reflect_path::Enum for #enum_path #ty_generics #where_reflect_clause {
             fn field(&self, #ref_name: &str) -> #FQOption<&dyn #bevy_reflect_path::PartialReflect> {
                  match #match_this {

crates/bevy_reflect/derive/src/impls/mod.rs

@@ -9,6 +9,8 @@ mod tuple_structs;
 mod typed;
 
 pub(crate) use assertions::impl_assertions;
+#[cfg(feature = "auto_register")]
+pub(crate) use common::reflect_auto_registration;
 pub(crate) use common::{common_partial_reflect_methods, impl_full_reflect};
 pub(crate) use enums::impl_enum;
 #[cfg(feature = "functions")]

crates/bevy_reflect/derive/src/impls/opaque.rs

@@ -55,6 +55,11 @@ pub(crate) fn impl_opaque(meta: &ReflectMeta) -> proc_macro2::TokenStream {
     #[cfg(feature = "functions")]
     let function_impls = crate::impls::impl_function_traits(meta, &where_clause_options);
 
+    #[cfg(not(feature = "auto_register"))]
+    let auto_register = None::<proc_macro2::TokenStream>;
+    #[cfg(feature = "auto_register")]
+    let auto_register = crate::impls::reflect_auto_registration(meta);
+
     let (impl_generics, ty_generics, where_clause) = type_path.generics().split_for_impl();
     let where_reflect_clause = where_clause_options.extend_where_clause(where_clause);
     let get_type_registration_impl = meta.get_type_registration(&where_clause_options);
@@ -70,6 +75,8 @@ pub(crate) fn impl_opaque(meta: &ReflectMeta) -> proc_macro2::TokenStream {
 
         #function_impls
 
+        #auto_register
+
         impl #impl_generics #bevy_reflect_path::PartialReflect for #type_path #ty_generics #where_reflect_clause  {
             #[inline]
             fn get_represented_type_info(&self) -> #FQOption<&'static #bevy_reflect_path::TypeInfo> {

crates/bevy_reflect/derive/src/impls/structs.rs

@@ -62,6 +62,11 @@ pub(crate) fn impl_struct(reflect_struct: &ReflectStruct) -> proc_macro2::TokenS
         .generics()
         .split_for_impl();
 
+    #[cfg(not(feature = "auto_register"))]
+    let auto_register = None::<proc_macro2::TokenStream>;
+    #[cfg(feature = "auto_register")]
+    let auto_register = crate::impls::reflect_auto_registration(reflect_struct.meta());
+
     let where_reflect_clause = where_clause_options.extend_where_clause(where_clause);
 
     quote! {
@@ -75,6 +80,8 @@ pub(crate) fn impl_struct(reflect_struct: &ReflectStruct) -> proc_macro2::TokenS
 
         #function_impls
 
+        #auto_register
+
         impl #impl_generics #bevy_reflect_path::Struct for #struct_path #ty_generics #where_reflect_clause {
             fn field(&self, name: &str) -> #FQOption<&dyn #bevy_reflect_path::PartialReflect> {
                 match name {

crates/bevy_reflect/derive/src/impls/tuple_structs.rs

@@ -50,6 +50,11 @@ pub(crate) fn impl_tuple_struct(reflect_struct: &ReflectStruct) -> proc_macro2::
         .generics()
         .split_for_impl();
 
+    #[cfg(not(feature = "auto_register"))]
+    let auto_register = None::<proc_macro2::TokenStream>;
+    #[cfg(feature = "auto_register")]
+    let auto_register = crate::impls::reflect_auto_registration(reflect_struct.meta());
+
     let where_reflect_clause = where_clause_options.extend_where_clause(where_clause);
 
     quote! {
@@ -63,6 +68,8 @@ pub(crate) fn impl_tuple_struct(reflect_struct: &ReflectStruct) -> proc_macro2::
 
         #function_impls
 
+        #auto_register
+
         impl #impl_generics #bevy_reflect_path::TupleStruct for #struct_path #ty_generics #where_reflect_clause {
             fn field(&self, index: usize) -> #FQOption<&dyn #bevy_reflect_path::PartialReflect> {
                 match index {

crates/bevy_reflect/derive/src/lib.rs

@@ -315,6 +315,12 @@ fn match_reflect_impls(ast: DeriveInput, source: ReflectImplSource) -> TokenStre
 /// #[reflect(@Required, @EditorTooltip::new("An ID is required!"))]
 /// struct Id(u8);
 /// ```
+/// ## `#[reflect(no_auto_register)]`
+///
+/// This attribute will opt-out of the automatic reflect type registration.
+///
+/// All non-generic types annotated with `#[derive(Reflect)]` are usually automatically registered on app startup.
+/// If this behavior is not desired, this attribute may be used to disable it for the annotated type.
 ///
 /// # Field Attributes
 ///