Make Reflect safe to implement (#5010)

# Objective

Currently, `Reflect` is unsafe to implement because of a contract in which `any` and `any_mut` must return `self`, or `downcast` will cause UB. This PR makes `Reflect` safe, makes `downcast` not use unsafe, and eliminates this contract. 

## Solution

This PR adds a method to `Reflect`, `any`. It also renames the old `any` to `as_any`.
`any` now takes a `Box<Self>` and returns a `Box<dyn Any>`. 

---

## Changelog

### Added:
- `any()` method
- `represents()` method

### Changed:
- `Reflect` is now a safe trait
- `downcast()` is now safe
- The old `any` is now called `as_any`, and `any_mut` is now `as_mut_any`

## Migration Guide

- Reflect derives should not have to change anything
- Manual reflect impls will need to remove the `unsafe` keyword, add `any()` implementations, and rename the old `any` and `any_mut` to `as_any` and `as_mut_any`.
- Calls to `any`/`any_mut` must be changed to `as_any`/`as_mut_any`

## Points of discussion:

- Should renaming `any` be avoided and instead name the new method `any_box`?
- ~~Could there be a performance regression from avoiding the unsafe? I doubt it, but this change does seem to introduce redundant checks.~~
- ~~Could/should `is` and `type_id()` be implemented differently? For example, moving `is` onto `Reflect` as an `fn(&self, TypeId) -> bool`~~


Co-authored-by: PROMETHIA-27 <42193387+PROMETHIA-27@users.noreply.github.com>

crates/bevy_reflect/bevy_reflect_derive/src/container_attributes.rs

@@ -208,7 +208,7 @@ impl ReflectTraits {
         match &self.partial_eq {
             TraitImpl::Implemented => Some(quote! {
                 fn reflect_partial_eq(&self, value: &dyn #bevy_reflect_path::Reflect) -> Option<bool> {
-                    let value = value.any();
+                    let value = value.as_any();
                     if let Some(value) = value.downcast_ref::<Self>() {
                         Some(std::cmp::PartialEq::eq(self, value))
                     } else {

crates/bevy_reflect/bevy_reflect_derive/src/from_reflect.rs

@@ -26,7 +26,7 @@ pub(crate) fn impl_value(
     TokenStream::from(quote! {
         impl #impl_generics #bevy_reflect_path::FromReflect for #type_name #ty_generics #where_clause  {
             fn from_reflect(reflect: &dyn #bevy_reflect_path::Reflect) -> Option<Self> {
-                Some(reflect.any().downcast_ref::<#type_name #ty_generics>()?.clone())
+                Some(reflect.as_any().downcast_ref::<#type_name #ty_generics>()?.clone())
             }
         }
     })

crates/bevy_reflect/bevy_reflect_derive/src/impls.rs

@@ -125,8 +125,7 @@ pub(crate) fn impl_struct(derive_data: &ReflectDeriveData) -> TokenStream {
             }
         }
 
-        // SAFE: any and any_mut both return self
-        unsafe impl #impl_generics #bevy_reflect_path::Reflect for #struct_name #ty_generics #where_clause {
+        impl #impl_generics #bevy_reflect_path::Reflect for #struct_name #ty_generics #where_clause {
             #[inline]
             fn type_name(&self) -> &str {
                 std::any::type_name::<Self>()
@@ -138,11 +137,17 @@ pub(crate) fn impl_struct(derive_data: &ReflectDeriveData) -> TokenStream {
             }
 
             #[inline]
-            fn any(&self) -> &dyn std::any::Any {
+            fn into_any(self: Box<Self>) -> Box<dyn std::any::Any> {
                 self
             }
+
             #[inline]
-            fn any_mut(&mut self) -> &mut dyn std::any::Any {
+            fn as_any(&self) -> &dyn std::any::Any {
+                self
+            }
+
+            #[inline]
+            fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
                 self
             }
 
@@ -275,8 +280,7 @@ pub(crate) fn impl_tuple_struct(derive_data: &ReflectDeriveData) -> TokenStream
             }
         }
 
-        // SAFE: any and any_mut both return self
-        unsafe impl #impl_generics #bevy_reflect_path::Reflect for #struct_name #ty_generics #where_clause {
+        impl #impl_generics #bevy_reflect_path::Reflect for #struct_name #ty_generics #where_clause {
             #[inline]
             fn type_name(&self) -> &str {
                 std::any::type_name::<Self>()
@@ -288,11 +292,17 @@ pub(crate) fn impl_tuple_struct(derive_data: &ReflectDeriveData) -> TokenStream
             }
 
             #[inline]
-            fn any(&self) -> &dyn std::any::Any {
+            fn into_any(self: Box<Self>) -> Box<dyn std::any::Any> {
                 self
             }
+
             #[inline]
-            fn any_mut(&mut self) -> &mut dyn std::any::Any {
+            fn as_any(&self) -> &dyn std::any::Any {
+                self
+            }
+
+            #[inline]
+            fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
                 self
             }
 
@@ -372,8 +382,7 @@ pub(crate) fn impl_value(
 
         #typed_impl
 
-        // SAFE: any and any_mut both return self
-        unsafe impl #impl_generics #bevy_reflect_path::Reflect for #type_name #ty_generics #where_clause  {
+        impl #impl_generics #bevy_reflect_path::Reflect for #type_name #ty_generics #where_clause  {
             #[inline]
             fn type_name(&self) -> &str {
                 std::any::type_name::<Self>()
@@ -385,12 +394,17 @@ pub(crate) fn impl_value(
             }
 
             #[inline]
-            fn any(&self) -> &dyn std::any::Any {
+            fn into_any(self: Box<Self>) -> Box<dyn std::any::Any> {
                 self
             }
 
             #[inline]
-            fn any_mut(&mut self) -> &mut dyn std::any::Any {
+            fn as_any(&self) -> &dyn std::any::Any {
+                self
+            }
+
+            #[inline]
+            fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
                 self
             }
 
@@ -411,7 +425,7 @@ pub(crate) fn impl_value(
 
             #[inline]
             fn apply(&mut self, value: &dyn #bevy_reflect_path::Reflect) {
-                let value = value.any();
+                let value = value.as_any();
                 if let Some(value) = value.downcast_ref::<Self>() {
                     *self = value.clone();
                 } else {

crates/bevy_reflect/src/array.rs

@@ -151,8 +151,7 @@ impl DynamicArray {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl Reflect for DynamicArray {
+impl Reflect for DynamicArray {
     #[inline]
     fn type_name(&self) -> &str {
         self.name.as_str()
@@ -164,12 +163,17 @@ unsafe impl Reflect for DynamicArray {
     }
 
     #[inline]
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
     #[inline]
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    #[inline]
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 

crates/bevy_reflect/src/impls/smallvec.rs

@@ -55,8 +55,7 @@ where
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl<T: smallvec::Array + Send + Sync + 'static> Reflect for SmallVec<T>
+impl<T: smallvec::Array + Send + Sync + 'static> Reflect for SmallVec<T>
 where
     T::Item: FromReflect + Clone,
 {
@@ -68,11 +67,15 @@ where
         <Self as Typed>::type_info()
     }
 
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 

crates/bevy_reflect/src/impls/std.rs

@@ -105,8 +105,7 @@ impl<T: FromReflect> List for Vec<T> {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl<T: FromReflect> Reflect for Vec<T> {
+impl<T: FromReflect> Reflect for Vec<T> {
     fn type_name(&self) -> &str {
         std::any::type_name::<Self>()
     }
@@ -115,11 +114,15 @@ unsafe impl<T: FromReflect> Reflect for Vec<T> {
         <Self as Typed>::type_info()
     }
 
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 
@@ -230,8 +233,7 @@ impl<K: Reflect + Eq + Hash, V: Reflect> Map for HashMap<K, V> {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl<K: Reflect + Eq + Hash, V: Reflect> Reflect for HashMap<K, V> {
+impl<K: Reflect + Eq + Hash, V: Reflect> Reflect for HashMap<K, V> {
     fn type_name(&self) -> &str {
         std::any::type_name::<Self>()
     }
@@ -240,11 +242,15 @@ unsafe impl<K: Reflect + Eq + Hash, V: Reflect> Reflect for HashMap<K, V> {
         <Self as Typed>::type_info()
     }
 
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 
@@ -350,8 +356,7 @@ impl<T: Reflect, const N: usize> Array for [T; N] {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl<T: Reflect, const N: usize> Reflect for [T; N] {
+impl<T: Reflect, const N: usize> Reflect for [T; N] {
     #[inline]
     fn type_name(&self) -> &str {
         std::any::type_name::<Self>()
@@ -362,12 +367,17 @@ unsafe impl<T: Reflect, const N: usize> Reflect for [T; N] {
     }
 
     #[inline]
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
     #[inline]
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    #[inline]
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 
@@ -465,8 +475,7 @@ impl_array_get_type_registration! {
     30 31 32
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl Reflect for Cow<'static, str> {
+impl Reflect for Cow<'static, str> {
     fn type_name(&self) -> &str {
         std::any::type_name::<Self>()
     }
@@ -475,11 +484,15 @@ unsafe impl Reflect for Cow<'static, str> {
         <Self as Typed>::type_info()
     }
 
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 
@@ -492,7 +505,7 @@ unsafe impl Reflect for Cow<'static, str> {
     }
 
     fn apply(&mut self, value: &dyn Reflect) {
-        let value = value.any();
+        let value = value.as_any();
         if let Some(value) = value.downcast_ref::<Self>() {
             *self = value.clone();
         } else {
@@ -525,7 +538,7 @@ unsafe impl Reflect for Cow<'static, str> {
     }
 
     fn reflect_partial_eq(&self, value: &dyn Reflect) -> Option<bool> {
-        let value = value.any();
+        let value = value.as_any();
         if let Some(value) = value.downcast_ref::<Self>() {
             Some(std::cmp::PartialEq::eq(self, value))
         } else {
@@ -552,7 +565,12 @@ impl GetTypeRegistration for Cow<'static, str> {
 
 impl FromReflect for Cow<'static, str> {
     fn from_reflect(reflect: &dyn crate::Reflect) -> Option<Self> {
-        Some(reflect.any().downcast_ref::<Cow<'static, str>>()?.clone())
+        Some(
+            reflect
+                .as_any()
+                .downcast_ref::<Cow<'static, str>>()?
+                .clone(),
+        )
     }
 }
 

crates/bevy_reflect/src/lib.rs

@@ -485,6 +485,42 @@ mod tests {
         assert!(foo.reflect_partial_eq(&dynamic_struct).unwrap());
     }
 
+    #[test]
+    fn reflect_downcast() {
+        #[derive(Reflect, Clone, Debug, PartialEq)]
+        struct Bar {
+            y: u8,
+            z: ::glam::Mat4,
+        }
+
+        #[derive(Reflect, Clone, Debug, PartialEq)]
+        struct Foo {
+            x: i32,
+            s: String,
+            b: Bar,
+            u: usize,
+            t: (Vec3, String),
+        }
+
+        let foo = Foo {
+            x: 123,
+            s: "String".to_string(),
+            b: Bar {
+                y: 255,
+                z: ::glam::Mat4::from_cols_array(&[
+                    0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0,
+                    15.0,
+                ]),
+            },
+            u: 1111111111111,
+            t: (Vec3::new(3.0, 2.0, 1.0), "Tuple String".to_string()),
+        };
+
+        let foo2: Box<dyn Reflect> = Box::new(foo.clone());
+
+        assert_eq!(foo, *foo2.downcast::<Foo>().unwrap());
+    }
+
     #[test]
     fn reflect_take() {
         #[derive(Reflect, Debug, PartialEq)]

crates/bevy_reflect/src/list.rs

@@ -163,8 +163,7 @@ impl List for DynamicList {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl Reflect for DynamicList {
+impl Reflect for DynamicList {
     #[inline]
     fn type_name(&self) -> &str {
         self.name.as_str()
@@ -176,12 +175,17 @@ unsafe impl Reflect for DynamicList {
     }
 
     #[inline]
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
     #[inline]
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    #[inline]
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 

crates/bevy_reflect/src/map.rs

@@ -212,8 +212,7 @@ impl Map for DynamicMap {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl Reflect for DynamicMap {
+impl Reflect for DynamicMap {
     fn type_name(&self) -> &str {
         &self.name
     }
@@ -223,11 +222,15 @@ unsafe impl Reflect for DynamicMap {
         <Self as Typed>::type_info()
     }
 
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 

crates/bevy_reflect/src/reflect.rs

@@ -2,7 +2,10 @@ use crate::{
     array_debug, list_debug, map_debug, serde::Serializable, struct_debug, tuple_debug,
     tuple_struct_debug, Array, List, Map, Struct, Tuple, TupleStruct, TypeInfo, Typed, ValueInfo,
 };
-use std::{any::Any, fmt::Debug};
+use std::{
+    any::{self, Any, TypeId},
+    fmt::Debug,
+};
 
 use crate::utility::NonGenericTypeInfoCell;
 pub use bevy_utils::AHasher as ReflectHasher;
@@ -46,15 +49,8 @@ pub enum ReflectMut<'a> {
 ///
 /// When using `#[derive(Reflect)]` with a struct or tuple struct, the suitable subtrait for that
 /// type (`Struct` or `TupleStruct`) is derived automatically.
-///
-/// # Safety
-/// Implementors _must_ ensure that [`Reflect::any`] and [`Reflect::any_mut`] both return the `self`
-/// value passed in. If this is not done, [`Reflect::downcast`](trait.Reflect.html#method.downcast)
-/// will be UB (and also just logically broken).
-pub unsafe trait Reflect: Any + Send + Sync {
-    /// Returns the [type name] of the underlying type.
-    ///
-    /// [type name]: std::any::type_name
+pub trait Reflect: Any + Send + Sync {
+    /// Returns the [type name][std::any::type_name] of the underlying type.
     fn type_name(&self) -> &str;
 
     /// Returns the [`TypeInfo`] of the underlying type.
@@ -67,11 +63,14 @@ pub unsafe trait Reflect: Any + Send + Sync {
     /// [`TypeRegistry::get_type_info`]: crate::TypeRegistry::get_type_info
     fn get_type_info(&self) -> &'static TypeInfo;
 
+    /// Returns the value as a [`Box<dyn Any>`][std::any::Any].
+    fn into_any(self: Box<Self>) -> Box<dyn Any>;
+
     /// Returns the value as a [`&dyn Any`][std::any::Any].
-    fn any(&self) -> &dyn Any;
+    fn as_any(&self) -> &dyn Any;
 
     /// Returns the value as a [`&mut dyn Any`][std::any::Any].
-    fn any_mut(&mut self) -> &mut dyn Any;
+    fn as_any_mut(&mut self) -> &mut dyn Any;
 
     /// Casts this type to a reflected value
     fn as_reflect(&self) -> &dyn Reflect;
@@ -210,18 +209,14 @@ impl Typed for dyn Reflect {
     }
 }
 
+#[deny(rustdoc::broken_intra_doc_links)]
 impl dyn Reflect {
     /// Downcasts the value to type `T`, consuming the trait object.
     ///
     /// If the underlying value is not of type `T`, returns `Err(self)`.
     pub fn downcast<T: Reflect>(self: Box<dyn Reflect>) -> Result<Box<T>, Box<dyn Reflect>> {
-        // SAFE?: Same approach used by std::any::Box::downcast. ReflectValue is always Any and type
-        // has been checked.
         if self.is::<T>() {
-            unsafe {
-                let raw: *mut dyn Reflect = Box::into_raw(self);
-                Ok(Box::from_raw(raw as *mut T))
-            }
+            Ok(self.into_any().downcast().unwrap())
         } else {
             Err(self)
         }
@@ -234,11 +229,26 @@ impl dyn Reflect {
         self.downcast::<T>().map(|value| *value)
     }
 
+    /// Returns `true` if the underlying value represents a value of type `T`, or `false`
+    /// otherwise.
+    ///
+    /// Read `is` for more information on underlying values and represented types.
+    #[inline]
+    pub fn represents<T: Reflect>(&self) -> bool {
+        self.type_name() == any::type_name::<T>()
+    }
+
     /// Returns `true` if the underlying value is of type `T`, or `false`
     /// otherwise.
+    ///
+    /// The underlying value is the concrete type that is stored in this `dyn` object;
+    /// it can be downcasted to. In the case that this underlying value "represents"
+    /// a different type, like the Dynamic\*\*\* types do, you can call `represents`
+    /// to determine what type they represent. Represented types cannot be downcasted
+    /// to, but you can use [`FromReflect`] to create a value of the represented type from them.
     #[inline]
     pub fn is<T: Reflect>(&self) -> bool {
-        self.any().is::<T>()
+        self.type_id() == TypeId::of::<T>()
     }
 
     /// Downcasts the value to type `T` by reference.
@@ -246,7 +256,7 @@ impl dyn Reflect {
     /// If the underlying value is not of type `T`, returns `None`.
     #[inline]
     pub fn downcast_ref<T: Reflect>(&self) -> Option<&T> {
-        self.any().downcast_ref::<T>()
+        self.as_any().downcast_ref::<T>()
     }
 
     /// Downcasts the value to type `T` by mutable reference.
@@ -254,6 +264,6 @@ impl dyn Reflect {
     /// If the underlying value is not of type `T`, returns `None`.
     #[inline]
     pub fn downcast_mut<T: Reflect>(&mut self) -> Option<&mut T> {
-        self.any_mut().downcast_mut::<T>()
+        self.as_any_mut().downcast_mut::<T>()
     }
 }

crates/bevy_reflect/src/struct_trait.rs

@@ -337,8 +337,7 @@ impl Struct for DynamicStruct {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl Reflect for DynamicStruct {
+impl Reflect for DynamicStruct {
     #[inline]
     fn type_name(&self) -> &str {
         &self.name
@@ -350,12 +349,17 @@ unsafe impl Reflect for DynamicStruct {
     }
 
     #[inline]
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
     #[inline]
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    #[inline]
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 

crates/bevy_reflect/src/tuple.rs

@@ -267,8 +267,7 @@ impl Tuple for DynamicTuple {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl Reflect for DynamicTuple {
+impl Reflect for DynamicTuple {
     #[inline]
     fn type_name(&self) -> &str {
         self.name()
@@ -280,12 +279,17 @@ unsafe impl Reflect for DynamicTuple {
     }
 
     #[inline]
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
     #[inline]
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    #[inline]
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 
@@ -460,8 +464,7 @@ macro_rules! impl_reflect_tuple {
             }
         }
 
-        // SAFE: any and any_mut both return self
-        unsafe impl<$($name: Reflect),*> Reflect for ($($name,)*) {
+        impl<$($name: Reflect),*> Reflect for ($($name,)*) {
             fn type_name(&self) -> &str {
                 std::any::type_name::<Self>()
             }
@@ -470,11 +473,15 @@ macro_rules! impl_reflect_tuple {
                 <Self as Typed>::type_info()
             }
 
-            fn any(&self) -> &dyn Any {
+            fn into_any(self: Box<Self>) -> Box<dyn Any> {
                 self
             }
 
-            fn any_mut(&mut self) -> &mut dyn Any {
+            fn as_any(&self) -> &dyn Any {
+                self
+            }
+
+            fn as_any_mut(&mut self) -> &mut dyn Any {
                 self
             }
 

crates/bevy_reflect/src/tuple_struct.rs

@@ -251,8 +251,7 @@ impl TupleStruct for DynamicTupleStruct {
     }
 }
 
-// SAFE: any and any_mut both return self
-unsafe impl Reflect for DynamicTupleStruct {
+impl Reflect for DynamicTupleStruct {
     #[inline]
     fn type_name(&self) -> &str {
         self.name.as_str()
@@ -264,12 +263,17 @@ unsafe impl Reflect for DynamicTupleStruct {
     }
 
     #[inline]
-    fn any(&self) -> &dyn Any {
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
         self
     }
 
     #[inline]
-    fn any_mut(&mut self) -> &mut dyn Any {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    #[inline]
+    fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
 

crates/bevy_reflect/src/type_info.rs

@@ -45,11 +45,12 @@ use std::any::{Any, TypeId};
 /// }
 ///
 /// #
-/// # unsafe impl Reflect for MyStruct {
+/// # impl Reflect for MyStruct {
 /// #   fn type_name(&self) -> &str { todo!() }
 /// #   fn get_type_info(&self) -> &'static TypeInfo { todo!() }
-/// #   fn any(&self) -> &dyn Any { todo!() }
-/// #   fn any_mut(&mut self) -> &mut dyn Any { todo!() }
+/// #   fn into_any(self: Box<Self>) -> Box<dyn Any> { todo!() }
+/// #   fn as_any(&self) -> &dyn Any { todo!() }
+/// #   fn as_any_mut(&mut self) -> &mut dyn Any { todo!() }
 /// #   fn as_reflect(&self) -> &dyn Reflect { todo!() }
 /// #   fn as_reflect_mut(&mut self) -> &mut dyn Reflect { todo!() }
 /// #   fn apply(&mut self, value: &dyn Reflect) { todo!() }

crates/bevy_reflect/src/utility.rs

@@ -34,11 +34,12 @@ use std::any::{Any, TypeId};
 ///   }
 /// }
 /// #
-/// # unsafe impl Reflect for Foo {
+/// # impl Reflect for Foo {
 /// #   fn type_name(&self) -> &str { todo!() }
 /// #   fn get_type_info(&self) -> &'static TypeInfo { todo!() }
-/// #   fn any(&self) -> &dyn Any { todo!() }
-/// #   fn any_mut(&mut self) -> &mut dyn Any { todo!() }
+/// #   fn into_any(self: Box<Self>) -> Box<dyn Any> { todo!() }
+/// #   fn as_any(&self) -> &dyn Any { todo!() }
+/// #   fn as_any_mut(&mut self) -> &mut dyn Any { todo!() }
 /// #   fn as_reflect(&self) -> &dyn Reflect { todo!() }
 /// #   fn as_reflect_mut(&mut self) -> &mut dyn Reflect { todo!() }
 /// #   fn apply(&mut self, value: &dyn Reflect) { todo!() }
@@ -94,11 +95,12 @@ impl NonGenericTypeInfoCell {
 ///   }
 /// }
 /// #
-/// # unsafe impl<T: Reflect> Reflect for Foo<T> {
+/// # impl<T: Reflect> Reflect for Foo<T> {
 /// #   fn type_name(&self) -> &str { todo!() }
 /// #   fn get_type_info(&self) -> &'static TypeInfo { todo!() }
-/// #   fn any(&self) -> &dyn Any { todo!() }
-/// #   fn any_mut(&mut self) -> &mut dyn Any { todo!() }
+/// #   fn into_any(self: Box<Self>) -> Box<dyn Any> { todo!() }
+/// #   fn as_any(&self) -> &dyn Any { todo!() }
+/// #   fn as_any_mut(&mut self) -> &mut dyn Any { todo!() }
 /// #   fn as_reflect(&self) -> &dyn Reflect { todo!() }
 /// #   fn as_reflect_mut(&mut self) -> &mut dyn Reflect { todo!() }
 /// #   fn apply(&mut self, value: &dyn Reflect) { todo!() }