Allow GodotExt syntax to be used for virtuals

examples/dodge-the-creeps/rust/src/hud.rs

@@ -61,7 +61,7 @@ impl Hud {
 }
 
 #[godot_api]
-impl CanvasLayerVirtual for Hud {
+impl GodotExt for Hud {
     fn init(base: Base<Self::Base>) -> Self {
         Self { base }
     }

examples/dodge-the-creeps/rust/src/main_scene.rs

@@ -126,7 +126,7 @@ impl Main {
 }
 
 #[godot_api]
-impl NodeVirtual for Main {
+impl GodotExt for Main {
     fn init(base: Base<Node>) -> Self {
         Main {
             mob_scene: PackedScene::new(),

examples/dodge-the-creeps/rust/src/mob.rs

@@ -47,7 +47,7 @@ impl Mob {
 }
 
 #[godot_api]
-impl RigidBody2DVirtual for Mob {
+impl GodotExt for Mob {
     fn init(base: Base<RigidBody2D>) -> Self {
         Mob {
             min_speed: 150.0,

examples/dodge-the-creeps/rust/src/player.rs

@@ -42,7 +42,7 @@ impl Player {
 }
 
 #[godot_api]
-impl Area2DVirtual for Player {
+impl GodotExt for Player {
     fn init(base: Base<Area2D>) -> Self {
         Player {
             speed: 400.0,

godot-core/src/obj/traits.rs

@@ -50,6 +50,9 @@ pub trait Share {
     fn share(&self) -> Self;
 }
 
+// Marker trait that exists only for documentation purposes.
+// pub trait GodotExt : private::Sealed {}
+
 /// Non-strict inheritance relationship in the Godot class hierarchy.
 ///
 /// `Derived: Inherits<Base>` means that either `Derived` is a subclass of `Base`, or the class `Base` itself (hence "non-strict").
@@ -164,7 +167,7 @@ pub mod cap {
         fn __register_exports();
     }
 
-    /// Auto-implemented for `#[godot_api] impl ***Virtual for MyClass` blocks
+    /// Auto-implemented for `#[godot_api] impl GodotExt for MyClass` blocks
     pub trait ImplementsGodotVirtual: GodotClass {
         #[doc(hidden)]
         fn __virtual_call(_name: &str) -> sys::GDExtensionClassCallVirtual;

godot-macros/src/derive_godot_class.rs

@@ -22,6 +22,9 @@ pub fn transform(decl: Declaration) -> ParseResult<TokenStream> {
     let class_name = &class.name;
     let class_name_str = class.name.to_string();
     let inherits_macro = format_ident!("inherits_transitive_{}", base_ty);
+    let virtual_trait = format_ident!("{}Virtual", base_ty);
+    let virtual_impl_macro = format_ident!("__gdext_virtual_impl_{}", class_name);
+    let virtual_call_macro = format_ident!("__gdext_virtual_call_{}", class_name);
 
     let prv = quote! { ::godot::private };
     let deref_impl = make_deref_impl(class_name, &fields);
@@ -60,6 +63,28 @@ pub fn transform(decl: Declaration) -> ParseResult<TokenStream> {
         });
 
         #prv::class_macros::#inherits_macro!(#class_name);
+
+        #[allow(non_snake_case)]
+        macro_rules! #virtual_impl_macro {
+            ( impl GodotExt for $Class:ident { $($tt:tt)* } ) => {
+                impl #virtual_trait for $Class { $($tt)* }
+            };
+
+            ( impl $Trait:ident for $Class:ident { $($tt:tt)* } ) => {
+                impl $Trait for $Class { $($tt)* }
+            };
+        }
+
+        #[allow(non_snake_case)]
+        macro_rules! #virtual_call_macro {
+            ( <Self as GodotExt> :: $function:ident( $($args:expr)* ) ) => {
+                <Self as #virtual_trait> :: $function( $($args)* )
+            };
+
+            ( <Self as $Trait:ident> :: $function:ident( $($args:expr)* ) ) => {
+                <Self as $Trait> :: $function( $($args)* )
+            };
+        }
     })
 }
 

godot-macros/src/godot_api.rs

@@ -6,9 +6,9 @@
 
 use crate::util;
 use crate::util::bail;
-use proc_macro2::{Ident, TokenStream};
-use quote::quote;
-use venial::{AttributeValue, Declaration, Error, Function, Impl, ImplMember};
+use proc_macro2::{Ident, TokenStream, TokenTree};
+use quote::{format_ident, quote};
+use venial::{AttributeValue, Declaration, Error, Function, Impl, ImplMember, TyExpr};
 
 pub fn transform(input_decl: Declaration) -> Result<TokenStream, Error> {
     let decl = match input_decl {
@@ -211,8 +211,13 @@ fn extract_attributes(method: &Function) -> Result<Option<BoundAttr>, Error> {
 // ----------------------------------------------------------------------------------------------------------------------------------------------
 
 /// Codegen for `#[godot_api] impl GodotExt for MyType`
-fn transform_trait_impl(original_impl: Impl) -> Result<TokenStream, Error> {
+fn transform_trait_impl(mut original_impl: Impl) -> Result<TokenStream, Error> {
     let (class_name, trait_name) = util::validate_trait_impl_virtual(&original_impl, "godot_api")?;
+    original_impl.trait_ty = Some(TyExpr {
+        tokens: vec![TokenTree::Ident(trait_name.clone())],
+    });
+    let original_impl = original_impl; // de-mutate
+
     let class_name_str = class_name.to_string();
 
     let mut godot_init_impl = TokenStream::new();
@@ -225,6 +230,8 @@ fn transform_trait_impl(original_impl: Impl) -> Result<TokenStream, Error> {
 
     let mut virtual_methods = vec![];
     let mut virtual_method_names = vec![];
+    let virtual_impl_macro = format_ident!("__gdext_virtual_impl_{}", class_name);
+    let virtual_call_macro = format_ident!("__gdext_virtual_call_{}", class_name);
 
     let prv = quote! { ::godot::private };
 
@@ -241,21 +248,23 @@ fn transform_trait_impl(original_impl: Impl) -> Result<TokenStream, Error> {
                 register_class_impl = quote! {
                     impl ::godot::obj::cap::GodotRegisterClass for #class_name {
                         fn __godot_register_class(builder: &mut ::godot::builder::GodotBuilder<Self>) {
-                            <Self as #trait_name>::register_class(builder)
+                             #virtual_call_macro! { <Self as #trait_name>::register_class(builder) }
                         }
                     }
                 };
 
-                register_fn = quote! { Some(#prv::ErasedRegisterFn {
-                    raw: #prv::callbacks::register_class_by_builder::<#class_name>
-                }) };
+                register_fn = quote! {
+                    Some(#prv::ErasedRegisterFn {
+                        raw: #prv::callbacks::register_class_by_builder::<#class_name>
+                    })
+                };
             }
 
             "init" => {
                 godot_init_impl = quote! {
                     impl ::godot::obj::cap::GodotInit for #class_name {
                         fn __godot_init(base: ::godot::obj::Base<Self::Base>) -> Self {
-                            <Self as #trait_name>::init(base)
+                            #virtual_call_macro! { <Self as #trait_name>::init(base) }
                         }
                     }
                 };
@@ -266,7 +275,7 @@ fn transform_trait_impl(original_impl: Impl) -> Result<TokenStream, Error> {
                 to_string_impl = quote! {
                     impl ::godot::obj::cap::GodotToString for #class_name {
                         fn __godot_to_string(&self) -> ::godot::builtin::GodotString {
-                            <Self as #trait_name>::to_string(self)
+                            #virtual_call_macro! { <Self as #trait_name>::to_string(self) }
                         }
                     }
                 };
@@ -297,7 +306,9 @@ fn transform_trait_impl(original_impl: Impl) -> Result<TokenStream, Error> {
     }
 
     let result = quote! {
-        #original_impl
+        #[doc(hidden)]
+        #virtual_impl_macro!(#original_impl);
+
         #godot_init_impl
         #to_string_impl
         #register_class_impl

godot-macros/src/lib.rs

@@ -21,6 +21,8 @@ pub fn derive_native_class(input: TokenStream) -> TokenStream {
     translate(input, derive_godot_class::transform)
 }
 
+/// Attribute to annotate `impl` blocks.
+#[doc(alias = "GodotExt")]
 #[proc_macro_attribute]
 pub fn godot_api(_meta: TokenStream, input: TokenStream) -> TokenStream {
     translate(input, godot_api::transform)

godot-macros/src/util.rs

@@ -380,8 +380,9 @@ pub(crate) fn validate_impl(
     validate_self(original_impl, attr)
 }
 
-/// Validates that the declaration is the of the form `impl Trait for
-/// SomeType`, where the name of `Trait` ends in `Virtual`.
+/// Validates that the declaration is the of the form `impl Trait for SomeType`, where the name of `Trait` ends in `Virtual`.
+///
+/// Returns (class_name, trait_name).
 pub(crate) fn validate_trait_impl_virtual(
     original_impl: &Impl,
     attr: &str,
@@ -390,10 +391,9 @@ pub(crate) fn validate_trait_impl_virtual(
     let typename = extract_typename(trait_name);
 
     // Validate trait
-    if !typename
-        .as_ref()
-        .map_or(false, |seg| seg.ident.to_string().ends_with("Virtual"))
-    {
+    if !typename.as_ref().map_or(false, |seg| {
+        seg.ident == "GodotExt" || seg.ident.to_string().ends_with("Virtual")
+    }) {
         return bail(
             format!("#[{attr}] for trait impls requires a virtual method trait (trait name should end in 'Virtual')"),
             original_impl,
@@ -407,6 +407,9 @@ pub(crate) fn validate_trait_impl_virtual(
     })
 }
 
+/// Check the `MyType` (self) part of `impl Trait for MyType`.
+///
+/// Returns the type name of `Self`, or error.
 fn validate_self(original_impl: &Impl, attr: &str) -> ParseResult<Ident> {
     if let Some(segment) = extract_typename(&original_impl.self_ty) {
         if segment.generic_args.is_none() {

itest/rust/src/codegen_test.rs

@@ -60,7 +60,7 @@ pub struct TestBaseRenamed {
 }
 
 #[godot_api]
-impl HttpRequestVirtual for TestBaseRenamed {
+impl GodotExt for TestBaseRenamed {
     fn init(base: Base<HttpRequest>) -> Self {
         TestBaseRenamed { base }
     }

itest/rust/src/export_test.rs

@@ -75,7 +75,7 @@ impl HasProperty {
 }
 
 #[godot_api]
-impl NodeVirtual for HasProperty {
+impl GodotExt for HasProperty {
     fn init(base: Base<Node>) -> Self {
         HasProperty {
             int_val: 0,

itest/rust/src/object_test.rs

@@ -637,7 +637,7 @@ pub struct ObjPayload {
 }
 
 #[godot_api]
-impl RefCountedVirtual for ObjPayload {
+impl GodotExt for ObjPayload {
     fn init(_base: Base<Self::Base>) -> Self {
         Self { value: 111 }
     }

itest/rust/src/virtual_methods_test.rs

@@ -35,7 +35,7 @@ struct VirtualMethodTest {
 impl VirtualMethodTest {}
 
 #[godot_api]
-impl RefCountedVirtual for VirtualMethodTest {
+impl GodotExt for VirtualMethodTest {
     fn to_string(&self) -> GodotString {
         format!("VirtualMethodTest[integer={}]", self.integer).into()
     }
@@ -50,7 +50,7 @@ struct ReadyVirtualTest {
 }
 
 #[godot_api]
-impl Node2DVirtual for ReadyVirtualTest {
+impl GodotExt for ReadyVirtualTest {
     fn init(base: Base<Node2D>) -> Self {
         ReadyVirtualTest {
             some_base: base,
@@ -73,7 +73,7 @@ struct TreeVirtualTest {
 }
 
 #[godot_api]
-impl Node2DVirtual for TreeVirtualTest {
+impl GodotExt for TreeVirtualTest {
     fn init(base: Base<Node2D>) -> Self {
         TreeVirtualTest {
             some_base: base,