fix(ExportEnum): handle non-enum input

Author: Bogay

gdnative-derive/src/export_enum.rs

@@ -4,7 +4,12 @@ use syn::DeriveInput;
 pub(crate) fn derive_export_enum(input: &DeriveInput) -> syn::Result<TokenStream2> {
     let derived_enum = match &input.data {
         syn::Data::Enum(data) => data,
-        _ => todo!("return error"),
+        _ => {
+            return Err(syn::Error::new(
+                input.ident.span(),
+                "#[derive(ExportEnum)] can only use on enum",
+            ))
+        }
     };
 
     let to_variant_impl = impl_to_variant(&input.ident, derived_enum)?;
@@ -59,19 +64,26 @@ fn impl_from_variant(enum_ty: &syn::Ident, data: &syn::DataEnum) -> syn::Result<
     Ok(impl_block)
 }
 
-fn impl_export(enum_ty: &syn::Ident, _data: &syn::DataEnum) -> syn::Result<TokenStream2> {
+fn impl_export(enum_ty: &syn::Ident, data: &syn::DataEnum) -> syn::Result<TokenStream2> {
+    let mappings = data.variants.iter().map(|variant| {
+        let ident = &variant.ident;
+        let key = stringify!(ident);
+        let val = quote! { #enum_ty::#ident as i64 };
+        quote! { (#key.to_string(), #val) }
+    });
     let impl_block = quote! {
         impl ::gdnative::export::Export for #enum_ty {
             type Hint = ::gdnative::export::hint::IntHint<i64>;
             #[inline]
             fn export_info(hint: Option<Self::Hint>) -> ::gdnative::export::ExportInfo {
                 if let Some(hint) = hint {
-                    if matches!(hint, ::gdnative::export::hint::IntHint::<i64>::Enum(_)) {
-                        return hint.export_info();
-                    }
+                    return hint.export_info();
+                } else {
+                    let mappings = vec![ #(#mappings),* ];
+                    let enum_hint = ::gdnative::export::hint::EnumHint::with_numbers(mappings);
+                    return ::gdnative::export::hint::IntHint::<i64>::Enum(enum_hint).export_info();
                 }
 
-                ::gdnative::export::ExportInfo::new(::gdnative::core_types::VariantType::I64)
             }
         }
     };