[Bug] sol! fails for structs with UDVT fields

[DaniPopes]

Component

sol! macro

What version of Alloy are you on?

Latest

Operating System

None

Describe the bug

The following code:

sol! {
    type Foo is uint256;
    struct Bar {
        Foo a;
    }
}

Fails with:

error[E0277]: the trait bound `Foo: SolStruct` is not satisfied
   --> crates/sol-types/tests/sol.rs:295:5
    |
295 | /     sol! {
296 | |         type Foo is uint256;
297 | |         struct Bar {
298 | |             Foo a;
299 | |         }
300 | |     }
    | |_____^ the trait `SolStruct` is not implemented for `Foo`
    |
    = note: this error originates in the macro `sol` (in Nightly builds, run with -Z macro-backtrace for more info)

---

The problem is here:

core/crates/sol-macro/src/expand/struct.rs

Lines 168 to 190 in 43a14af

	fn expand_eip712_components(fields: &ast::Parameters<syn::token::Semi>) -> TokenStream {
	let bits: Vec<TokenStream> = fields
	.iter()
	.filter(|f| f.ty.is_custom())
	.map(|field| {
	let ty = expand_type(&field.ty);
	quote! {
	components.push(<#ty as ::alloy_sol_types::SolStruct>::eip712_root_type());
	components.extend(<#ty as ::alloy_sol_types::SolStruct>::eip712_components());
	}
	})
	.collect();
	if bits.is_empty() {
	quote! { ::alloy_sol_types::private::Vec::with_capacity(0) }
	} else {
	quote! {
	let mut components = ::alloy_sol_types::private::Vec::new();
	#(#bits)*
	components
	}
	}
	}

#ty as SolStruct does not hold for UDVTs, which do not implement SolStruct.