Simple derive macro for better struct support

stylus-proc/src/abi.rs

@@ -0,0 +1,18 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, ItemStruct};
+
+pub fn derive_abi_type(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as ItemStruct);
+    let name = &input.ident;
+    let name_str = name.to_string();
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
+    quote! {
+        impl #impl_generics stylus_sdk::abi::AbiType for #name #ty_generics #where_clause {
+            type SolType = Self;
+            const ABI: stylus_sdk::abi::ConstString = stylus_sdk::abi::ConstString::new(#name_str);
+        }
+    }
+    .into()
+}

stylus-proc/src/lib.rs

@@ -30,6 +30,7 @@ macro_rules! error {
     }};
 }
 
+mod abi;
 mod calls;
 mod methods;
 mod storage;
@@ -565,3 +566,20 @@ pub fn public(attr: TokenStream, input: TokenStream) -> TokenStream {
 pub fn external(attr: TokenStream, input: TokenStream) -> TokenStream {
     public(attr, input)
 }
+
+/// Implements the AbiType for arbitrary structs, allowing them to be used in external method
+/// return types and parameters. This derive is intended to be used within the
+/// [alloy_sol_types::sol] macro.
+///
+/// ```ignore
+/// sol! {
+///     #[derive(AbiType)]
+///     pub struct Foo {
+///         u256 bar;
+///     }
+/// }
+/// ```
+#[proc_macro_derive(AbiType)]
+pub fn derive_abi_type(input: TokenStream) -> TokenStream {
+    abi::derive_abi_type(input)
+}