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Refactor bundle derive #19749

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Merged
merged 4 commits into from
Jun 20, 2025
Merged

Refactor bundle derive #19749

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fc5a0dd
refactor Bundle derive implementation
SkiFire13 Jun 19, 2025
81a8c64
fix bug with multiple ignored fields in Bundle
SkiFire13 Jun 19, 2025
eff1277
Add reason for unused annotation
SkiFire13 Jun 20, 2025
616da83
Replace allow with expect
SkiFire13 Jun 20, 2025
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124 changes: 52 additions & 72 deletions crates/bevy_ecs/macros/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ use crate::{
use bevy_macro_utils::{derive_label, ensure_no_collision, get_struct_fields, BevyManifest};
use proc_macro::TokenStream;
use proc_macro2::{Ident, Span};
use quote::{format_ident, quote};
use quote::{format_ident, quote, ToTokens};
use syn::{
parse_macro_input, parse_quote, punctuated::Punctuated, spanned::Spanned, token::Comma,
ConstParam, Data, DataStruct, DeriveInput, GenericParam, Index, TypeParam,
Expand Down Expand Up @@ -79,14 +79,16 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
let mut field_kind = Vec::with_capacity(named_fields.len());

for field in named_fields {
let mut kind = BundleFieldKind::Component;

for attr in field
.attrs
.iter()
.filter(|a| a.path().is_ident(BUNDLE_ATTRIBUTE_NAME))
{
if let Err(error) = attr.parse_nested_meta(|meta| {
if meta.path.is_ident(BUNDLE_ATTRIBUTE_IGNORE_NAME) {
field_kind.push(BundleFieldKind::Ignore);
kind = BundleFieldKind::Ignore;
Ok(())
} else {
Err(meta.error(format!(
Expand All @@ -98,7 +100,7 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
}
}

field_kind.push(BundleFieldKind::Component);
field_kind.push(kind);
}

let field = named_fields
Expand All @@ -111,82 +113,33 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
.map(|field| &field.ty)
.collect::<Vec<_>>();

let mut field_component_ids = Vec::new();
let mut field_get_component_ids = Vec::new();
let mut field_get_components = Vec::new();
let mut field_from_components = Vec::new();
let mut field_required_components = Vec::new();
let mut active_field_types = Vec::new();
let mut active_field_tokens = Vec::new();
let mut inactive_field_tokens = Vec::new();
for (((i, field_type), field_kind), field) in field_type
.iter()
.enumerate()
.zip(field_kind.iter())
.zip(field.iter())
{
let field_tokens = match field {
Some(field) => field.to_token_stream(),
None => Index::from(i).to_token_stream(),
};
match field_kind {
BundleFieldKind::Component => {
field_component_ids.push(quote! {
<#field_type as #ecs_path::bundle::Bundle>::component_ids(components, &mut *ids);
});
field_required_components.push(quote! {
<#field_type as #ecs_path::bundle::Bundle>::register_required_components(components, required_components);
});
field_get_component_ids.push(quote! {
<#field_type as #ecs_path::bundle::Bundle>::get_component_ids(components, &mut *ids);
});
match field {
Some(field) => {
field_get_components.push(quote! {
self.#field.get_components(&mut *func);
});
field_from_components.push(quote! {
#field: <#field_type as #ecs_path::bundle::BundleFromComponents>::from_components(ctx, &mut *func),
});
}
None => {
let index = Index::from(i);
field_get_components.push(quote! {
self.#index.get_components(&mut *func);
});
field_from_components.push(quote! {
#index: <#field_type as #ecs_path::bundle::BundleFromComponents>::from_components(ctx, &mut *func),
});
}
}
active_field_types.push(field_type);
active_field_tokens.push(field_tokens);
}

BundleFieldKind::Ignore => {
field_from_components.push(quote! {
#field: ::core::default::Default::default(),
});
}
BundleFieldKind::Ignore => inactive_field_tokens.push(field_tokens),
}
}
let generics = ast.generics;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let struct_name = &ast.ident;

let from_components = attributes.impl_from_components.then(|| quote! {
// SAFETY:
// - ComponentId is returned in field-definition-order. [from_components] uses field-definition-order
#[allow(deprecated)]
unsafe impl #impl_generics #ecs_path::bundle::BundleFromComponents for #struct_name #ty_generics #where_clause {
#[allow(unused_variables, non_snake_case)]
unsafe fn from_components<__T, __F>(ctx: &mut __T, func: &mut __F) -> Self
where
__F: FnMut(&mut __T) -> #ecs_path::ptr::OwningPtr<'_>
{
Self{
#(#field_from_components)*
}
}
}
});

let attribute_errors = &errors;

TokenStream::from(quote! {
#(#attribute_errors)*

let bundle_impl = quote! {
// SAFETY:
// - ComponentId is returned in field-definition-order. [get_components] uses field-definition-order
// - `Bundle::get_components` is exactly once for each member. Rely's on the Component -> Bundle implementation to properly pass
Expand All @@ -196,27 +149,27 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
fn component_ids(
components: &mut #ecs_path::component::ComponentsRegistrator,
ids: &mut impl FnMut(#ecs_path::component::ComponentId)
){
#(#field_component_ids)*
) {
#(<#active_field_types as #ecs_path::bundle::Bundle>::component_ids(components, ids);)*
}

fn get_component_ids(
components: &#ecs_path::component::Components,
ids: &mut impl FnMut(Option<#ecs_path::component::ComponentId>)
){
#(#field_get_component_ids)*
) {
#(<#active_field_types as #ecs_path::bundle::Bundle>::get_component_ids(components, &mut *ids);)*
}

fn register_required_components(
components: &mut #ecs_path::component::ComponentsRegistrator,
required_components: &mut #ecs_path::component::RequiredComponents
){
#(#field_required_components)*
) {
#(<#active_field_types as #ecs_path::bundle::Bundle>::register_required_components(components, required_components);)*
}
}
};

#from_components

let dynamic_bundle_impl = quote! {
#[allow(deprecated)]
impl #impl_generics #ecs_path::bundle::DynamicBundle for #struct_name #ty_generics #where_clause {
type Effect = ();
Expand All @@ -226,9 +179,36 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
self,
func: &mut impl FnMut(#ecs_path::component::StorageType, #ecs_path::ptr::OwningPtr<'_>)
) {
#(#field_get_components)*
#(<#active_field_types as #ecs_path::bundle::DynamicBundle>::get_components(self.#active_field_tokens, &mut *func);)*
}
}
};

let from_components_impl = attributes.impl_from_components.then(|| quote! {
// SAFETY:
// - ComponentId is returned in field-definition-order. [from_components] uses field-definition-order
#[allow(deprecated)]
unsafe impl #impl_generics #ecs_path::bundle::BundleFromComponents for #struct_name #ty_generics #where_clause {
#[allow(unused_variables, non_snake_case)]
unsafe fn from_components<__T, __F>(ctx: &mut __T, func: &mut __F) -> Self
where
__F: FnMut(&mut __T) -> #ecs_path::ptr::OwningPtr<'_>
{
Self {
#(#active_field_tokens: <#active_field_types as #ecs_path::bundle::BundleFromComponents>::from_components(ctx, &mut *func),)*
#(#inactive_field_tokens: ::core::default::Default::default(),)*
}
}
}
});

let attribute_errors = &errors;

TokenStream::from(quote! {
#(#attribute_errors)*
#bundle_impl
#from_components_impl
#dynamic_bundle_impl
})
}

Expand Down
9 changes: 9 additions & 0 deletions crates/bevy_ecs/src/bundle.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2397,4 +2397,13 @@ mod tests {

assert_eq!(world.resource::<Count>().0, 3);
}

#[derive(Bundle)]
#[expect(unused, reason = "tests the output of the derive macro is valid")]
struct Ignore {
#[bundle(ignore)]
foo: i32,
#[bundle(ignore)]
bar: i32,
}
}