feat(Export): report compile error for all non-fieldless enum variants

gdnative-derive/src/export.rs

@@ -7,7 +7,7 @@ pub(crate) fn derive_export(input: &DeriveInput) -> syn::Result<TokenStream2> {
  _ => {
  return Err(syn::Error::new(
  input.ident.span(),
- "#[derive(Export)] can only use on enum",
+ "#[derive(Export)] only supports fieldless enums",
  ))
  }
  };
@@ -17,23 +17,35 @@ pub(crate) fn derive_export(input: &DeriveInput) -> syn::Result<TokenStream2> {
 }
 
 fn impl_export(enum_ty: &syn::Ident, data: &syn::DataEnum) -> syn::Result<TokenStream2> {
- let mappings = {
- let mut m = Vec::with_capacity(data.variants.len());
-
- for variant in &data.variants {
- if !matches!(variant.fields, Fields::Unit) {
- return Err(syn::Error::new(
+ let err = data
+ .variants
+ .iter()
+ .filter_map(|variant| {
+ (!matches!(variant.fields, Fields::Unit)).then(|| {
+ syn::Error::new(
  variant.ident.span(),
  "#[derive(Export)] only supports fieldless enums",
- ));
- }
+ )
+ })
+ })
+ .reduce(|mut acc, err| {
+ acc.combine(err);
+ acc
+ });
+ if let Some(err) = err {
+ return Err(err);
+ }
+
+ let mappings = data
+ .variants
+ .iter()
+ .map(|variant| {
  let key = &variant.ident;
  let val = quote! { #enum_ty::#key as i64 };
- m.push(quote! { (stringify!(#key).to_string(), #val) });
- }
+ quote! { (stringify!(#key).to_string(), #val) }
+ })
+ .collect::<Vec<_>>();
 
- m
- };
  let impl_block = quote! {
  impl ::gdnative::export::Export for #enum_ty {
  type Hint = ::gdnative::export::hint::IntHint<i64>;

gdnative/tests/ui/export_fail_01.rs

@@ -3,6 +3,7 @@ use gdnative::prelude::*;
 #[derive(Export, ToVariant)]
 pub enum Foo {
  Bar(String),
+ Baz { a: i32, b: u32 },
 }
 
 fn main() {}

gdnative/tests/ui/export_fail_01.stderr

@@ -3,3 +3,9 @@ error: #[derive(Export)] only supports fieldless enums
  |
 5 | Bar(String),
  | ^^^
+
+error: #[derive(Export)] only supports fieldless enums
+ --> tests/ui/export_fail_01.rs:6:5
+ |
+6 | Baz { a: i32, b: u32 },
+ | ^^^