Change WhereClauseOptions::active_fields to active_types

This could have been part of #19876, which deduplicated the fields. It's
also simpler and more efficient to keep the (short-lived) active types
as an `IndexSet<Type>`, and avoid converting them to a `Vec<Type>` and
then a `Box<[Type]>`.

Author: nnethercote

crates/bevy_reflect/derive/src/derive_data.rs

@@ -607,13 +607,11 @@ impl<'a> ReflectStruct<'a> {
     }
 
     /// Get a collection of types which are exposed to the reflection API
-    pub fn active_types(&self) -> Vec<Type> {
-        // Collect via `IndexSet` to eliminate duplicate types.
+    pub fn active_types(&self) -> IndexSet<Type> {
+        // Collect into an `IndexSet` to eliminate duplicate types.
         self.active_fields()
             .map(|field| field.reflected_type().clone())
             .collect::<IndexSet<_>>()
-            .into_iter()
-            .collect::<Vec<_>>()
     }
 
     /// Get an iterator of fields which are exposed to the reflection API.
@@ -636,7 +634,7 @@ impl<'a> ReflectStruct<'a> {
     }
 
     pub fn where_clause_options(&self) -> WhereClauseOptions {
-        WhereClauseOptions::new_with_fields(self.meta(), self.active_types().into_boxed_slice())
+        WhereClauseOptions::new_with_types(self.meta(), self.active_types())
     }
 
     /// Generates a `TokenStream` for `TypeInfo::Struct` or `TypeInfo::TupleStruct` construction.
@@ -854,13 +852,11 @@ impl<'a> ReflectEnum<'a> {
     }
 
     /// Get a collection of types which are exposed to the reflection API
-    pub fn active_types(&self) -> Vec<Type> {
-        // Collect via `IndexSet` to eliminate duplicate types.
+    pub fn active_types(&self) -> IndexSet<Type> {
+        // Collect into an `IndexSet` to eliminate duplicate types.
         self.active_fields()
             .map(|field| field.reflected_type().clone())
             .collect::<IndexSet<_>>()
-            .into_iter()
-            .collect::<Vec<_>>()
     }
 
     /// Get an iterator of fields which are exposed to the reflection API
@@ -869,7 +865,7 @@ impl<'a> ReflectEnum<'a> {
     }
 
     pub fn where_clause_options(&self) -> WhereClauseOptions {
-        WhereClauseOptions::new_with_fields(self.meta(), self.active_types().into_boxed_slice())
+        WhereClauseOptions::new_with_types(self.meta(), self.active_types())
     }
 
     /// Returns the `GetTypeRegistration` impl as a `TokenStream`.

crates/bevy_reflect/derive/src/where_clause_options.rs

@@ -1,28 +1,26 @@
 use crate::derive_data::ReflectMeta;
 use bevy_macro_utils::fq_std::{FQAny, FQSend, FQSync};
+use indexmap::IndexSet;
 use proc_macro2::TokenStream;
 use quote::{quote, ToTokens};
 use syn::{punctuated::Punctuated, Token, Type, WhereClause};
 
 /// Options defining how to extend the `where` clause for reflection.
 pub(crate) struct WhereClauseOptions<'a, 'b> {
     meta: &'a ReflectMeta<'b>,
-    active_fields: Box<[Type]>,
+    active_types: IndexSet<Type>,
 }
 
 impl<'a, 'b> WhereClauseOptions<'a, 'b> {
     pub fn new(meta: &'a ReflectMeta<'b>) -> Self {
         Self {
             meta,
-            active_fields: Box::new([]),
+            active_types: IndexSet::new(),
         }
     }
 
-    pub fn new_with_fields(meta: &'a ReflectMeta<'b>, active_fields: Box<[Type]>) -> Self {
-        Self {
-            meta,
-            active_fields,
-        }
+    pub fn new_with_types(meta: &'a ReflectMeta<'b>, active_types: IndexSet<Type>) -> Self {
+        Self { meta, active_types }
     }
 
     /// Extends the `where` clause for a type with additional bounds needed for the reflection impls.
@@ -157,7 +155,7 @@ impl<'a, 'b> WhereClauseOptions<'a, 'b> {
             // construct `NamedField` and `UnnamedField` instances for the `Typed` impl.
             // Likewise, `GetTypeRegistration` is always required for active fields since
             // they are used to register the type's dependencies.
-            Some(self.active_fields.iter().map(move |ty| {
+            Some(self.active_types.iter().map(move |ty| {
                 quote!(
                     #ty : #reflect_bound
                         + #bevy_reflect_path::TypePath