Add subtrait for reborrowing QueryData types

crates/bevy_ecs/macros/src/query_data.rs

@@ -275,6 +275,22 @@ pub fn derive_query_data_impl(input: TokenStream) -> TokenStream {
                     }
                 }
 
+                impl #user_impl_generics #path::query::ReborrowQueryData
+                for #read_only_struct_name #user_ty_generics #user_where_clauses
+                // Make these HRTBs with an unused lifetime parameter to allow trivial constraints
+                // See https://github.com/rust-lang/rust/issues/48214
+                where #(for<'__a> #field_types: #path::query::QueryData<ReadOnly: #path::query::ReborrowQueryData>,)* {
+                    fn reborrow<'wlong: 'short, 'slong: 'short, 'short>(
+                        item: &'short mut Self::Item<'wlong, 'slong>,
+                    ) -> Self::Item<'short, 'short> {
+                        #read_only_item_struct_name {
+                            #(
+                                #field_members: <#read_only_field_types>::reborrow(&mut item.#field_members),
+                            )*
+                        }
+                    }
+                }
+
                 impl #user_impl_generics #path::query::ReleaseStateQueryData
                 for #read_only_struct_name #user_ty_generics #user_where_clauses
                 // Make these HRTBs with an unused lifetime parameter to allow trivial constraints
@@ -346,6 +362,22 @@ pub fn derive_query_data_impl(input: TokenStream) -> TokenStream {
                 }
             }
 
+            impl #user_impl_generics #path::query::ReborrowQueryData
+            for #struct_name #user_ty_generics #user_where_clauses
+            // Make these HRTBs with an unused lifetime parameter to allow trivial constraints
+            // See https://github.com/rust-lang/rust/issues/48214
+            where #(for<'__a> #field_types: #path::query::ReborrowQueryData,)* {
+                fn reborrow<'wlong: 'short, 'slong: 'short, 'short>(
+                    item: &'short mut Self::Item<'wlong, 'slong>,
+                ) -> Self::Item<'short, 'short> {
+                    #item_struct_name {
+                        #(
+                            #field_members: <#field_types>::reborrow(&mut item.#field_members),
+                        )*
+                    }
+                }
+            }
+
             impl #user_impl_generics #path::query::ReleaseStateQueryData
             for #struct_name #user_ty_generics #user_where_clauses
             // Make these HRTBs with an unused lifetime parameter to allow trivial constraints

crates/bevy_ecs/src/change_detection/params.rs

@@ -360,6 +360,21 @@ impl<'w, T: ?Sized> Ref<'w, T> {
         self.ticks.last_run = last_run;
         self.ticks.this_run = this_run;
     }
+
+    /// Returns a `Mut<>` with a smaller lifetime.
+    /// This is useful if you have `&Ref<T>`, but you need a `Ref<T>`.
+    pub fn reborrow(&self) -> Ref<'_, T> {
+        Ref {
+            value: self.value,
+            ticks: ComponentTicksRef {
+                added: self.ticks.added,
+                changed: self.ticks.changed,
+                changed_by: self.ticks.changed_by,
+                last_run: self.ticks.last_run,
+                this_run: self.ticks.this_run,
+            },
+        }
+    }
 }
 
 impl<'w, 'a, T> IntoIterator for &'a Ref<'w, T>