Add a trait to get the vtable for a type

helper_crates/vtable/macro/macro.rs

@@ -449,13 +449,16 @@ pub fn vtable(_attr: TokenStream, item: TokenStream) -> TokenStream {
         #vis use #module_name::*;
 
         #[macro_export]
+        /// Implements HasStaticVTable<XXXVTable> for the given type
         macro_rules! #static_vtable_macro_name {
             ($ty:ty) => {
-                    {
+                unsafe impl ::vtable::HasStaticVTable<#vtable_name> for $ty {
+                    const VTABLE: #vtable_name = {
                         type T = $ty;
                         #vtable_name {
                             #(#vtable_ctor)*
                         }
+                    };
                 }
             }
         }
@@ -463,3 +466,46 @@ pub fn vtable(_attr: TokenStream, item: TokenStream) -> TokenStream {
     //     println!("{}", result);
     result.into()
 }
+/*
+#[proc_macro_attribute]
+pub fn static_vtable(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let mut input = parse_macro_input!(item as ItemStatic);
+
+    let ty = parse_macro_input!(attr as Type);
+
+    let input_ty = &input.ty;
+
+    let vtable_type = if let Type::Path(pat) = &**input_ty {
+        if let Some(seg) = pat.path.segments.last() {
+            seg.ident.clone()
+        } else {
+            return Error::new(proc_macro2::Span::call_site(), "Could not find the VTableType")
+                .to_compile_error()
+                .into();
+        }
+    } else {
+        return Error::new(proc_macro2::Span::call_site(), "Could not find the VTableType")
+            .to_compile_error()
+            .into();
+    };
+
+    if !vtable_type.to_string().ends_with("VTable") {
+        return Error::new(input.ident.span(), "The type does not ends in 'VTable'")
+            .to_compile_error()
+            .into();
+    }
+
+    let mac = quote::format_ident!("{}_static", vtable_type);
+    input.expr =
+        Box::new(parse2(quote!(<#ty as ::vtable::HasStaticVTable<#input_ty>>::VTABLE)).unwrap());
+
+    quote!(
+        #input
+        unsafe impl ::vtable::HasStaticVTable<#input_ty> for #ty
+        {
+            const VTABLE : <#input_ty as ::vtable::VTableMeta>::VTable =  #mac!(#ty);
+        }
+    )
+    .into()
+}
+*/

helper_crates/vtable/src/lib.rs

@@ -19,6 +19,16 @@ pub trait VTableMetaDrop: VTableMeta {
     unsafe fn drop(ptr: *mut Self::Target);
 }
 
+/// Allow to associate a VTable to a type.
+pub unsafe trait HasStaticVTable<VT>
+where
+    VT: ?Sized + VTableMeta,
+    VT::VTable: 'static,
+{
+    /// Savety: must be a valid VTable for Self
+    const VTABLE: VT::VTable;
+}
+
 #[derive(Copy, Clone)]
 /// The inner structure of VRef, VRefMut, and VBox.
 ///

helper_crates/vtable/tests/test_vtable.rs

@@ -39,7 +39,8 @@ impl HelloConsts for SomeStruct {
     const CONSTANT: usize = 88;
 }
 
-static SOME_STRUCT_TYPE: HelloVTable = HelloVTable_static!(SomeStruct);
+HelloVTable_static!(SomeStruct);
+static SOME_STRUCT_TYPE: HelloVTable = SomeStruct::VTABLE;
 
 #[test]
 fn test() {

sixtyfps_runtime/corelib/abi/datastructures.rs

@@ -293,10 +293,5 @@ pub static QT_BUTTON_VTABLE: ItemVTable = ItemVTable {
 };
 */
 
-#[allow(non_upper_case_globals)]
-#[no_mangle]
-pub static RectangleVTable: ItemVTable = ItemVTable_static!(crate::abi::primitives::Rectangle);
-
-#[allow(non_upper_case_globals)]
-#[no_mangle]
-pub static ImageVTable: ItemVTable = ItemVTable_static!(crate::abi::primitives::Image);
+ItemVTable_static!(crate::abi::primitives::Image);
+ItemVTable_static!(crate::abi::primitives::Rectangle);

sixtyfps_runtime/corelib/abi/primitives.rs

@@ -1,6 +1,9 @@
 #![allow(non_upper_case_globals)]
 
-use super::datastructures::{CachedRenderingData, Item, ItemConsts, LayoutInfo, RenderingInfo};
+use super::datastructures::{
+    CachedRenderingData, Item, ItemConsts, ItemVTable, LayoutInfo, RenderingInfo,
+};
+use vtable::HasStaticVTable;
 
 /// FIXME:  more properties
 #[repr(C)]
@@ -80,4 +83,8 @@ impl ItemConsts for Image {
         Image::field_offsets().cached_rendering_data as isize;
 }
 
-pub use super::datastructures::{ImageVTable, RectangleVTable};
+#[no_mangle]
+pub static RectangleVTable: ItemVTable = Image::VTABLE;
+
+#[no_mangle]
+pub static ImageVTable: ItemVTable = Rectangle::VTABLE;