5aa520eac0
# Objective `#[derive(Reflect)]` derives `Typed` impls whose `type_info` methods contain useless calls to `with_custom_attributes` and `with_docs`, e.g.: ``` ::bevy::reflect::NamedField:🆕:<f32>("x") .with_custom_attributes( ::bevy::reflect::attributes::CustomAttributes::default() ) .with_docs(::core::option::Option::None), ``` This hurts compile times and makes the `cargo expand` output harder to read. It might also hurt runtime speed, depending on whether the compiler can optimize away the no-op methods. Avoiding this will help with #19873. ## Solution Check if the attributes/docs are empty before appending the method calls. ## Testing I used `cargo expand` to confirm the useless calls are no longer produced. `-Zmacro-stats` outputs tells me this reduces the size of the `Reflect` impls produced for `bevy_ui` from 1_544_696 bytes to 1_511_214 bytes, a 2.2% drop. Only a small improvement, but it's a start.
47 lines
1.2 KiB
Rust
47 lines
1.2 KiB
Rust
use proc_macro2::TokenStream;
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use quote::quote;
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use syn::{parse::ParseStream, Expr, Path, Token};
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#[derive(Default, Clone)]
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pub(crate) struct CustomAttributes {
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attributes: Vec<Expr>,
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}
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impl CustomAttributes {
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/// Generates a `TokenStream` for `CustomAttributes` construction.
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pub fn to_tokens(&self, bevy_reflect_path: &Path) -> TokenStream {
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let attributes = self.attributes.iter().map(|value| {
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quote! {
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.with_attribute(#value)
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}
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});
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quote! {
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#bevy_reflect_path::attributes::CustomAttributes::default()
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#(#attributes)*
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}
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}
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/// Inserts a custom attribute into the list.
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pub fn push(&mut self, value: Expr) -> syn::Result<()> {
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self.attributes.push(value);
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Ok(())
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}
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/// Is the collection empty?
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pub fn is_empty(&self) -> bool {
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self.attributes.is_empty()
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}
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/// Parse `@` (custom attribute) attribute.
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///
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/// Examples:
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/// - `#[reflect(@Foo))]`
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/// - `#[reflect(@Bar::baz("qux"))]`
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/// - `#[reflect(@0..256u8)]`
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pub fn parse_custom_attribute(&mut self, input: ParseStream) -> syn::Result<()> {
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input.parse::<Token![@]>()?;
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self.push(input.parse()?)
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}
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}
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