Make Require an unsafe trait

Discourages users from implementing it themselves, since it is purely for documentation purposes.

Co-Authored-By: JoshValjosh <[email protected]>

Author: bushrat011899

crates/bevy_ecs/macros/src/component.rs

@@ -220,7 +220,7 @@ pub fn derive_component(input: TokenStream) -> TokenStream {
                 quote! {
                     /// If not already present, the required component will be inserted using
                     #[doc = #insertion_info]
-                    impl #impl_generics #bevy_ecs_path::component::Require<#path> for #struct_name #type_generics #where_clause {}
+                    unsafe impl #impl_generics #bevy_ecs_path::component::Require<#path> for #struct_name #type_generics #where_clause {}
                 }
             });
 

crates/bevy_ecs/src/component.rs

@@ -456,7 +456,13 @@ pub trait Component: Send + Sync + 'static {
 }
 
 /// Indicates this [`Component`] requires another [`Component`] `C`.
-pub trait Require<C: Component>: Component {}
+/// This trait is similar to [`Eq`] in the sense that it is up to the implementer to ensure `C` is
+/// appropriately registered as a required component.
+///
+/// # Safety
+///
+/// Implementing this trait must be done in tandem with updating the implementation of [`Component::register_required_components`].
+pub unsafe trait Require<C: Component>: Component {}
 
 mod private {
     pub trait Seal {}