Fixed bounds for normal FromReflect derive

Author: MrGVSV

crates/bevy_reflect/bevy_reflect_derive/src/container_attributes.rs

@@ -170,7 +170,10 @@ pub(crate) struct ReflectTraits {
 }
 
 impl ReflectTraits {
-    pub fn from_metas(metas: Punctuated<Meta, Comma>) -> Result<Self, syn::Error> {
+    pub fn from_metas(
+        metas: Punctuated<Meta, Comma>,
+        is_from_reflect_derive: bool,
+    ) -> Result<Self, syn::Error> {
         let mut traits = ReflectTraits::default();
         for meta in &metas {
             match meta {
@@ -245,7 +248,14 @@ impl ReflectTraits {
                             syn::Expr::Lit(syn::ExprLit {
                                 lit: syn::Lit::Bool(lit),
                                 ..
-                            }) => Some(lit.clone()),
+                            }) => {
+                                // Overrride `lit` if this is a `FromReflect` derive.
+                                // This typically means a user is opting out of the default implementation
+                                // from the `Reflect` derive and using the `FromReflect` derive directly instead.
+                                is_from_reflect_derive
+                                    .then(|| LitBool::new(true, Span::call_site()))
+                                    .or_else(|| Some(lit.clone()))
+                            }
                             _ => {
                                 return Err(syn::Error::new(
                                     pair.value.span(),
@@ -366,7 +376,7 @@ impl ReflectTraits {
 
 impl Parse for ReflectTraits {
     fn parse(input: ParseStream) -> syn::Result<Self> {
-        ReflectTraits::from_metas(Punctuated::<Meta, Comma>::parse_terminated(input)?)
+        ReflectTraits::from_metas(Punctuated::<Meta, Comma>::parse_terminated(input)?, false)
     }
 }
 

crates/bevy_reflect/bevy_reflect_derive/src/derive_data.rs

@@ -134,7 +134,10 @@ enum ReflectMode {
 }
 
 impl<'a> ReflectDerive<'a> {
-    pub fn from_input(input: &'a DeriveInput) -> Result<Self, syn::Error> {
+    pub fn from_input(
+        input: &'a DeriveInput,
+        is_from_reflect_derive: bool,
+    ) -> Result<Self, syn::Error> {
         let mut traits = ReflectTraits::default();
         // Should indicate whether `#[reflect_value]` was used.
         let mut reflect_mode = None;
@@ -159,6 +162,7 @@ impl<'a> ReflectDerive<'a> {
                     reflect_mode = Some(ReflectMode::Normal);
                     let new_traits = ReflectTraits::from_metas(
                         meta_list.parse_args_with(Punctuated::<Meta, Comma>::parse_terminated)?,
+                        is_from_reflect_derive,
                     )?;
                     traits.merge(new_traits)?;
                 }
@@ -173,6 +177,7 @@ impl<'a> ReflectDerive<'a> {
                     reflect_mode = Some(ReflectMode::Value);
                     let new_traits = ReflectTraits::from_metas(
                         meta_list.parse_args_with(Punctuated::<Meta, Comma>::parse_terminated)?,
+                        is_from_reflect_derive,
                     )?;
                     traits.merge(new_traits)?;
                 }

crates/bevy_reflect/bevy_reflect_derive/src/lib.rs

@@ -156,7 +156,7 @@ pub(crate) static TYPE_NAME_ATTRIBUTE_NAME: &str = "type_name";
 pub fn derive_reflect(input: TokenStream) -> TokenStream {
     let ast = parse_macro_input!(input as DeriveInput);
 
-    let derive_data = match ReflectDerive::from_input(&ast) {
+    let derive_data = match ReflectDerive::from_input(&ast, false) {
         Ok(data) => data,
         Err(err) => return err.into_compile_error().into(),
     };
@@ -232,7 +232,7 @@ pub fn derive_reflect(input: TokenStream) -> TokenStream {
 pub fn derive_from_reflect(input: TokenStream) -> TokenStream {
     let ast = parse_macro_input!(input as DeriveInput);
 
-    let derive_data = match ReflectDerive::from_input(&ast) {
+    let derive_data = match ReflectDerive::from_input(&ast, true) {
         Ok(data) => data,
         Err(err) => return err.into_compile_error().into(),
     };
@@ -266,7 +266,7 @@ pub fn derive_from_reflect(input: TokenStream) -> TokenStream {
 #[proc_macro_derive(TypePath, attributes(type_path, type_name))]
 pub fn derive_type_path(input: TokenStream) -> TokenStream {
     let ast = parse_macro_input!(input as DeriveInput);
-    let derive_data = match ReflectDerive::from_input(&ast) {
+    let derive_data = match ReflectDerive::from_input(&ast, false) {
         Ok(data) => data,
         Err(err) => return err.into_compile_error().into(),
     };
@@ -434,7 +434,7 @@ pub fn impl_reflect_value(input: TokenStream) -> TokenStream {
 #[proc_macro]
 pub fn impl_reflect_struct(input: TokenStream) -> TokenStream {
     let ast = parse_macro_input!(input as DeriveInput);
-    let derive_data = match ReflectDerive::from_input(&ast) {
+    let derive_data = match ReflectDerive::from_input(&ast, false) {
         Ok(data) => data,
         Err(err) => return err.into_compile_error().into(),
     };

crates/bevy_reflect_compile_fail_tests/tests/reflect_derive/from_reflect.fail.rs

@@ -1,4 +1,4 @@
-use bevy_reflect::Reflect;
+use bevy_reflect::{FromReflect, Reflect};
 
 // Reason: Cannot have conflicting `from_reflect` attributes
 #[derive(Reflect)]
@@ -16,4 +16,10 @@ struct Bar {
     value: String,
 }
 
+// Reason: Conflicting `FromReflect` implementations
+#[derive(Reflect, FromReflect)]
+struct Baz {
+    value: String,
+}
+
 fn main() {}

crates/bevy_reflect_compile_fail_tests/tests/reflect_derive/from_reflect.fail.stderr

@@ -9,3 +9,13 @@ error: `from_reflect` already set to true
    |
 14 | #[reflect(from_reflect = false)]
    |                          ^^^^^
+
+error[E0119]: conflicting implementations of trait `FromReflect` for type `Baz`
+  --> tests/reflect_derive/from_reflect.fail.rs:20:19
+   |
+20 | #[derive(Reflect, FromReflect)]
+   |          -------  ^^^^^^^^^^^ conflicting implementation for `Baz`
+   |          |
+   |          first implementation here
+   |
+   = note: this error originates in the derive macro `FromReflect` (in Nightly builds, run with -Z macro-backtrace for more info)

crates/bevy_reflect_compile_fail_tests/tests/reflect_derive/from_reflect.pass.rs

@@ -1,4 +1,4 @@
-use bevy_reflect::Reflect;
+use bevy_reflect::{FromReflect, Reflect};
 
 #[derive(Reflect)]
 #[reflect(from_reflect = false)]
@@ -14,4 +14,10 @@ struct Bar {
     value: String,
 }
 
+#[derive(Reflect, FromReflect)]
+#[reflect(from_reflect = false)]
+struct Baz {
+    value: String,
+}
+
 fn main() {}

examples/reflection/reflection.rs

@@ -33,7 +33,7 @@ fn main() {
 /// To do this, you can either define a `#[reflect(default = "...")]` attribute on the ignored field, or
 /// opt-out of `FromReflect`'s auto-derive using the `#[reflect(from_reflect = false)]` attribute.
 #[derive(Reflect)]
-#[from_reflect(auto_derive = false)]
+#[reflect(from_reflect = false)]
 pub struct Foo {
     a: usize,
     nested: Bar,