refactor(contract): derive procedural macros (#2152)

* refactor: use Result<_, Error>

* fix: report both errors during parsing

* refactor: abigen derive results

* update Event derive

* refactor: derive utils

* fmt Display derive

* fmt Codec derive

* refactor: derives

* fix artifacts

* chore: clippy

Cargo.lock

@@ -1392,6 +1392,7 @@ version = "1.0.2"
 dependencies = [
  "ethers-contract-abigen",
  "ethers-core",
+ "eyre",
  "hex",
  "proc-macro2",
  "quote",

ethers-contract/ethers-contract-derive/Cargo.toml

@@ -20,12 +20,14 @@ proc-macro = true
 ethers-core = { version = "^1.0.0", path = "../../ethers-core" }
 ethers-contract-abigen = { version = "^1.0.0", path = "../ethers-contract-abigen", default-features = false }
 
-serde_json = "1.0.53"
-hex = { version = "0.4.3", default-features = false, features = ["std"] }
 proc-macro2 = "1.0"
 quote = "1.0"
 syn = "1.0.12"
 
+serde_json = "1.0.53"
+hex = { version = "0.4.3", default-features = false, features = ["std"] }
+eyre = "0.6"
+
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]

ethers-contract/ethers-contract-derive/src/abi_ty.rs

@@ -4,42 +4,32 @@ use crate::utils;
 use ethers_core::macros::ethers_core_crate;
 use proc_macro2::{Ident, Literal, TokenStream};
 use quote::{quote, quote_spanned};
-use syn::{parse::Error, spanned::Spanned as _, Data, DeriveInput, Fields, Variant};
+use syn::{parse::Error, spanned::Spanned, Data, DeriveInput, Fields, Variant};
 
 /// Generates the tokenize implementation
-pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream {
+pub fn derive_tokenizeable_impl(input: &DeriveInput) -> Result<TokenStream, Error> {
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
     let name = &input.ident;
-    let generic_params = input.generics.params.iter().map(|p| quote! { #p });
-    let generic_params = quote! { #(#generic_params,)* };
 
-    let generic_args = input.generics.type_params().map(|p| {
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
-        let name = &p.ident;
+    let generic_predicates = where_clause.map(|c| &c.predicates);
-        quote_spanned! { p.ident.span() => #name }
-    });
-
-    let generic_args = quote! { #(#generic_args,)* };
-
-    let generic_predicates = match input.generics.where_clause {
-        Some(ref clause) => {
-            let predicates = clause.predicates.iter().map(|p| quote! { #p });
-            quote! { #(#predicates,)* }
-        }
-        None => quote! {},
-    };
 
     let (tokenize_predicates, params_len, init_struct_impl, into_token_impl) = match input.data {
         Data::Struct(ref data) => match data.fields {
             Fields::Named(ref fields) => {
                 let tokenize_predicates = fields.named.iter().map(|f| {
                     let ty = &f.ty;
-                    quote_spanned! { f.span() => #ty: #core_crate::abi::Tokenize }
+                    quote_spanned! { f.span() => #ty: #ethers_core::abi::Tokenize }
                 });
                 let tokenize_predicates = quote! { #(#tokenize_predicates,)* };
 
                 let assignments = fields.named.iter().map(|f| {
                     let name = f.ident.as_ref().expect("Named fields have names");
-                    quote_spanned! { f.span() => #name: #core_crate::abi::Tokenizable::from_token(iter.next().expect("The iter is guaranteed to be something due to the size check"))? }
+                    quote_spanned! { f.span() =>
+                        #name: #ethers_core::abi::Tokenizable::from_token(
+                            iter.next().expect("The iter is guaranteed to be something due to the size check")
+                        )?
+                    }
                 });
                 let init_struct_impl = quote! { Self { #(#assignments,)* } };
 
@@ -54,12 +44,16 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
             Fields::Unnamed(ref fields) => {
                 let tokenize_predicates = fields.unnamed.iter().map(|f| {
                     let ty = &f.ty;
-                    quote_spanned! { f.span() => #ty: #core_crate::abi::Tokenize }
+                    quote_spanned! { f.span() => #ty: #ethers_core::abi::Tokenize }
                 });
                 let tokenize_predicates = quote! { #(#tokenize_predicates,)* };
 
                 let assignments = fields.unnamed.iter().map(|f| {
-                    quote_spanned! { f.span() => #core_crate::abi::Tokenizable::from_token(iter.next().expect("The iter is guaranteed to be something due to the size check"))? }
+                    quote_spanned! { f.span() =>
+                        #ethers_core::abi::Tokenizable::from_token(
+                            iter.next().expect("The iter is guaranteed to be something due to the size check")
+                        )?
+                    }
                 });
                 let init_struct_impl = quote! { Self(#(#assignments,)* ) };
 
@@ -71,17 +65,11 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
 
                 (tokenize_predicates, fields.unnamed.len(), init_struct_impl, into_token_impl)
             }
-            Fields::Unit => return tokenize_unit_type(&input.ident),
+            Fields::Unit => return Ok(tokenize_unit_type(&input.ident)),
         },
-        Data::Enum(ref data) => {
+        Data::Enum(ref data) => return tokenize_enum(name, data.variants.iter()),
-            return match tokenize_enum(name, data.variants.iter()) {
-                Ok(tokens) => tokens,
-                Err(err) => err.to_compile_error(),
-            }
-        }
         Data::Union(_) => {
-            return Error::new(input.span(), "EthAbiType cannot be derived for unions")
+            return Err(Error::new(input.span(), "EthAbiType cannot be derived for unions"))
-                .to_compile_error()
         }
     };
 
@@ -95,14 +83,14 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
             // can't encode an empty struct
             // TODO: panic instead?
             quote! {
-                #core_crate::abi::Token::Tuple(Vec::new())
+                #ethers_core::abi::Token::Tuple(Vec::new())
             },
         ),
         _ => {
             let from_token = quote! {
-                if let #core_crate::abi::Token::Tuple(tokens) = token {
+                if let #ethers_core::abi::Token::Tuple(tokens) = token {
                     if tokens.len() != #params_len {
-                        return Err(#core_crate::abi::InvalidOutputType(::std::format!(
+                        return Err(#ethers_core::abi::InvalidOutputType(::std::format!(
                             "Expected {} tokens, got {}: {:?}",
                             #params_len,
                             tokens.len(),
@@ -114,7 +102,7 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
 
                     Ok(#init_struct_impl)
                 } else {
-                    Err(#core_crate::abi::InvalidOutputType(::std::format!(
+                    Err(#ethers_core::abi::InvalidOutputType(::std::format!(
                         "Expected Tuple, got {:?}",
                         token
                     )))
@@ -122,7 +110,7 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
             };
 
             let into_token = quote! {
-                #core_crate::abi::Token::Tuple(
+                #ethers_core::abi::Token::Tuple(
                     ::std::vec![
                         #into_token_impl
                     ]
@@ -132,50 +120,51 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
         }
     };
 
-    let params = match utils::derive_param_type_with_abi_type(input, "EthAbiType") {
+    let params = utils::derive_param_type_with_abi_type(input, "EthAbiType")?;
-        Ok(params) => params,
-        Err(err) => return err.to_compile_error(),
-    };
-    quote! {
 
-        impl<#generic_params> #core_crate::abi::AbiType for #name<#generic_args>  {
+    Ok(quote! {
-            fn param_type() -> #core_crate::abi::ParamType {
+        impl #impl_generics #ethers_core::abi::AbiType for #name #ty_generics #where_clause {
+            fn param_type() -> #ethers_core::abi::ParamType {
                 #params
             }
         }
 
-       impl<#generic_params> #core_crate::abi::AbiArrayType for #name<#generic_args> {}
+        impl #impl_generics #ethers_core::abi::AbiArrayType for #name #ty_generics #where_clause {}
 
-         impl<#generic_params> #core_crate::abi::Tokenizable for #name<#generic_args>
+        impl #impl_generics #ethers_core::abi::Tokenizable for #name #ty_generics
         where
             #generic_predicates
             #tokenize_predicates
         {
-
+            fn from_token(token: #ethers_core::abi::Token) -> ::std::result::Result<Self, #ethers_core::abi::InvalidOutputType>
-             fn from_token(token: #core_crate::abi::Token) -> ::std::result::Result<Self, #core_crate::abi::InvalidOutputType> where
+            where
-                 Self: Sized {
+                Self: Sized,
+            {
                 #from_token_impl
             }
 
-             fn into_token(self) -> #core_crate::abi::Token {
+            fn into_token(self) -> #ethers_core::abi::Token {
                 #into_token_impl
             }
         }
 
-        impl<#generic_params> #core_crate::abi::TokenizableItem for #name<#generic_args>
+        impl #impl_generics #ethers_core::abi::TokenizableItem for #name #ty_generics
         where
             #generic_predicates
             #tokenize_predicates
         {}
-    }
+    })
 }
 
 fn tokenize_unit_type(name: &Ident) -> TokenStream {
     let ethers_core = ethers_core_crate();
+
     quote! {
         impl #ethers_core::abi::Tokenizable for #name {
-             fn from_token(token: #ethers_core::abi::Token) -> ::std::result::Result<Self, #ethers_core::abi::InvalidOutputType> where
+            fn from_token(token: #ethers_core::abi::Token) -> ::std::result::Result<Self, #ethers_core::abi::InvalidOutputType>
-                 Self: Sized {
+            where
+                Self: Sized,
+            {
                 if let #ethers_core::abi::Token::Tuple(tokens) = token {
                     if !tokens.is_empty() {
                         Err(#ethers_core::abi::InvalidOutputType(::std::format!(
@@ -197,6 +186,7 @@ fn tokenize_unit_type(name: &Ident) -> TokenStream {
                 #ethers_core::abi::Token::Tuple(::std::vec::Vec::new())
             }
         }
+
         impl #ethers_core::abi::TokenizableItem for #name {}
     }
 }
@@ -210,7 +200,7 @@ fn tokenize_unit_type(name: &Ident) -> TokenStream {
 fn tokenize_enum<'a>(
     enum_name: &Ident,
     variants: impl Iterator<Item = &'a Variant> + 'a,
-) -> ::std::result::Result<TokenStream, Error> {
+) -> Result<TokenStream, Error> {
     let ethers_core = ethers_core_crate();
 
     let mut into_tokens = TokenStream::new();
@@ -251,9 +241,10 @@ fn tokenize_enum<'a>(
 
     Ok(quote! {
         impl #ethers_core::abi::Tokenizable for #enum_name {
-
+            fn from_token(token: #ethers_core::abi::Token) -> ::std::result::Result<Self, #ethers_core::abi::InvalidOutputType>
-             fn from_token(token: #ethers_core::abi::Token) -> ::std::result::Result<Self, #ethers_core::abi::InvalidOutputType> where
+            where
-                 Self: Sized {
+                Self: Sized,
+            {
                 #from_tokens
                 Err(#ethers_core::abi::InvalidOutputType("Failed to decode all type variants".to_string()))
             }
@@ -264,6 +255,7 @@ fn tokenize_enum<'a>(
                 }
             }
         }
+
         impl #ethers_core::abi::TokenizableItem for #enum_name {}
     })
 }

ethers-contract/ethers-contract-derive/src/abigen.rs

@@ -8,14 +8,15 @@ use ethers_contract_abigen::{
     Abigen,
 };
 use ethers_core::abi::{Function, FunctionExt, Param, StateMutability};
+use eyre::Result;
 use proc_macro2::{Span, TokenStream as TokenStream2};
 use quote::ToTokens;
-use std::{collections::HashSet, error::Error};
+use std::collections::HashSet;
 use syn::{
     braced,
     ext::IdentExt,
     parenthesized,
-    parse::{Error as ParseError, Parse, ParseStream, Result as ParseResult},
+    parse::{Error, Parse, ParseStream, Result as ParseResult},
     Ident, LitStr, Path, Token,
 };
 
@@ -26,13 +27,13 @@ pub(crate) struct Contracts {
 }
 
 impl Contracts {
-    pub(crate) fn expand(self) -> ::std::result::Result<TokenStream2, syn::Error> {
+    pub(crate) fn expand(self) -> Result<TokenStream2, Error> {
         let mut expansions = Vec::with_capacity(self.inner.len());
 
         // expand all contracts
         for (span, contract) in self.inner {
-            let contract = Self::expand_contract(contract)
+            let contract =
-                .map_err(|err| syn::Error::new(span, err.to_string()))?;
+                Self::expand_contract(contract).map_err(|err| Error::new(span, err.to_string()))?;
             expansions.push(contract);
         }
 
@@ -40,10 +41,8 @@ impl Contracts {
         Ok(MultiExpansion::new(expansions).expand_inplace())
     }
 
-    fn expand_contract(
+    fn expand_contract(contract: ContractArgs) -> Result<(ExpandedContract, Context)> {
-        contract: ContractArgs,
+        contract.into_builder()?.expand()
-    ) -> Result<(ExpandedContract, Context), Box<dyn Error>> {
-        Ok(contract.into_builder()?.expand()?)
     }
 }
 
@@ -66,7 +65,7 @@ pub(crate) struct ContractArgs {
 }
 
 impl ContractArgs {
-    fn into_builder(self) -> Result<Abigen, Box<dyn Error>> {
+    fn into_builder(self) -> Result<Abigen> {
         let mut builder = Abigen::new(&self.name, &self.abi)?;
 
         for parameter in self.parameters.into_iter() {
@@ -151,13 +150,13 @@ impl Parse for Parameter {
                     let mut aliases = HashSet::new();
                     for method in parsed {
                         if !signatures.insert(method.signature.clone()) {
-                            return Err(ParseError::new(
+                            return Err(Error::new(
                                 method.span(),
                                 "duplicate method signature in `abigen!` macro invocation",
                             ))
                         }
                         if !aliases.insert(method.alias.clone()) {
-                            return Err(ParseError::new(
+                            return Err(Error::new(
                                 method.span(),
                                 "duplicate method alias in `abigen!` macro invocation",
                             ))
@@ -181,10 +180,7 @@ impl Parse for Parameter {
                 Parameter::Derives(derives)
             }
             _ => {
-                return Err(ParseError::new(
+                return Err(Error::new(name.span(), format!("unexpected named parameter `{name}`")))
-                    name.span(),
-                    format!("unexpected named parameter `{name}`"),
-                ))
             }
         };
 
@@ -211,7 +207,7 @@ impl Parse for Method {
                 .iter()
                 .map(|ident| {
                     let kind = serde_json::from_value(serde_json::json!(&ident.to_string()))
-                        .map_err(|err| ParseError::new(ident.span(), err))?;
+                        .map_err(|err| Error::new(ident.span(), err))?;
                     Ok(Param { name: "".into(), kind, internal_type: None })
                 })
                 .collect::<ParseResult<Vec<_>>>()?;

ethers-contract/ethers-contract-derive/src/call.rs

@@ -10,50 +10,40 @@ use quote::quote;
 use syn::{parse::Error, DeriveInput};
 
 /// Generates the `ethcall` trait support
-pub(crate) fn derive_eth_call_impl(input: DeriveInput) -> TokenStream {
+pub(crate) fn derive_eth_call_impl(input: DeriveInput) -> Result<TokenStream, Error> {
-    let attributes = match parse_calllike_attributes(&input, "ethcall") {
+    let attributes = parse_calllike_attributes(&input, "ethcall")?;
-        Ok(attributes) => attributes,
-        Err(errors) => return errors,
-    };
 
     let function_call_name =
         attributes.name.map(|(s, _)| s).unwrap_or_else(|| input.ident.to_string());
 
-    let mut function = if let Some((src, span)) = attributes.abi {
+    let mut function = if let Some((abi, span)) = attributes.abi {
-        let raw_function_sig = src.trim_start_matches("function ").trim_start();
+        let sig = abi.trim_start_matches("function ").trim_start();
         // try to parse as solidity function
-        if let Ok(fun) = HumanReadableParser::parse_function(&src) {
+        match HumanReadableParser::parse_function(&abi) {
-            fun
+            Ok(fun) => fun,
-        } else {
+            Err(parse_err) => {
-            // try to determine the abi by using its fields at runtime
+                return derive_trait_impls_with_abi_type(&input, &function_call_name, Some(sig))
-            return match derive_trait_impls_with_abi_type(
+                    .map_err(|e| {
-                &input,
+                        let mut error = Error::new(span, parse_err);
-                &function_call_name,
+                        error.combine(Error::new(span, e));
-                Some(raw_function_sig),
+                        error
-            ) {
+                    })
-                Ok(derived) => derived,
-                Err(err) => {
-                    Error::new(span, format!("Unable to determine ABI for `{src}` : {err}"))
-                        .to_compile_error()
-                }
             }
         }
     } else {
         // try to determine the abi by using its fields at runtime
-        return match derive_trait_impls_with_abi_type(&input, &function_call_name, None) {
+        return derive_trait_impls_with_abi_type(&input, &function_call_name, None)
-            Ok(derived) => derived,
-            Err(err) => err.to_compile_error(),
-        }
     };
     function.name = function_call_name.clone();
-    let abi = function.abi_signature();
+
+    let sig = function.abi_signature();
     let selector = utils::selector(function.selector());
     let decode_impl = derive_decode_impl_from_params(&function.inputs, ident("EthCall"));
 
     derive_trait_impls(
         &input,
         &function_call_name,
-        quote! {#abi.into()},
+        quote!(#sig.into()),
         Some(selector),
         decode_impl,
     )
@@ -65,17 +55,14 @@ fn derive_trait_impls_with_abi_type(
     function_call_name: &str,
     abi_signature: Option<&str>,
 ) -> Result<TokenStream, Error> {
-    let abi_signature = if let Some(abi) = abi_signature {
+    let mut abi_signature = if let Some(sig) = abi_signature {
-        quote! {#abi}
+        quote!(#sig)
     } else {
-        utils::derive_abi_signature_with_abi_type(input, function_call_name, "EthCall")?
+        utils::abi_signature_with_abi_type(input, function_call_name, "EthCall")?
-    };
-
-    let abi_signature = quote! {
-         #abi_signature.into()
     };
+    abi_signature.extend(quote!(.into()));
     let decode_impl = derive_decode_impl_with_abi_type(input, ident("EthCall"))?;
-    Ok(derive_trait_impls(input, function_call_name, abi_signature, None, decode_impl))
+    derive_trait_impls(input, function_call_name, abi_signature, None, decode_impl)
 }
 
 /// Generates the EthCall implementation
@@ -85,26 +72,25 @@ pub fn derive_trait_impls(
     abi_signature: TokenStream,
     selector: Option<TokenStream>,
     decode_impl: TokenStream,
-) -> TokenStream {
+) -> Result<TokenStream, Error> {
     // the ethers crates to use
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
-    let contract_crate = ethers_contract_crate();
+    let ethers_contract = ethers_contract_crate();
     let struct_name = &input.ident;
 
     let selector = selector.unwrap_or_else(|| {
         quote! {
-             #core_crate::utils::id(Self::abi_signature())
+            #ethers_core::utils::id(Self::abi_signature())
         }
     });
 
     let ethcall_impl = quote! {
-        impl #contract_crate::EthCall for #struct_name {
+        impl #ethers_contract::EthCall for #struct_name {
-
             fn function_name() -> ::std::borrow::Cow<'static, str> {
                 #function_call_name.into()
             }
 
-            fn selector() -> #core_crate::types::Selector {
+            fn selector() -> #ethers_core::types::Selector {
                 #selector
             }
 
@@ -113,10 +99,10 @@ pub fn derive_trait_impls(
             }
         }
     };
-    let codec_impl = derive_codec_impls(input, decode_impl, ident("EthCall"));
+    let codec_impl = derive_codec_impls(input, decode_impl, ident("EthCall"))?;
 
-    quote! {
+    Ok(quote! {
         #ethcall_impl
         #codec_impl
-    }
+    })
 }

ethers-contract/ethers-contract-derive/src/calllike.rs

@@ -7,7 +7,7 @@ use ethers_core::{
 };
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::quote;
-use syn::{parse::Error, spanned::Spanned as _, AttrStyle, DeriveInput, Lit, Meta, NestedMeta};
+use syn::{parse::Error, spanned::Spanned, AttrStyle, DeriveInput, Lit, Meta, NestedMeta};
 
 /// All the attributes the `EthCall`/`EthError` macro supports
 #[derive(Default)]
@@ -20,7 +20,7 @@ pub struct EthCalllikeAttributes {
 pub fn parse_calllike_attributes(
     input: &DeriveInput,
     attr_name: &str,
-) -> Result<EthCalllikeAttributes, TokenStream> {
+) -> Result<EthCalllikeAttributes, Error> {
     let mut result = EthCalllikeAttributes::default();
     for a in input.attrs.iter() {
         if let AttrStyle::Outer = a.style {
@@ -33,15 +33,13 @@ pub fn parse_calllike_attributes(
                                     return Err(Error::new(
                                         path.span(),
                                         format!("unrecognized {attr_name} parameter"),
-                                    )
+                                    ))
-                                    .to_compile_error())
                                 }
                                 Meta::List(meta) => {
                                     return Err(Error::new(
                                         meta.path.span(),
                                         format!("unrecognized {attr_name} parameter"),
-                                    )
+                                    ))
-                                    .to_compile_error())
                                 }
                                 Meta::NameValue(meta) => {
                                     if meta.path.is_ident("name") {
@@ -53,15 +51,13 @@ pub fn parse_calllike_attributes(
                                                 return Err(Error::new(
                                                     meta.span(),
                                                     "name already specified",
-                                                )
+                                                ))
-                                                .to_compile_error())
                                             }
                                         } else {
                                             return Err(Error::new(
                                                 meta.span(),
                                                 "name must be a string",
-                                            )
+                                            ))
-                                            .to_compile_error())
                                         }
                                     } else if meta.path.is_ident("abi") {
                                         if let Lit::Str(ref lit_str) = meta.lit {
@@ -72,22 +68,19 @@ pub fn parse_calllike_attributes(
                                                 return Err(Error::new(
                                                     meta.span(),
                                                     "abi already specified",
-                                                )
+                                                ))
-                                                .to_compile_error())
                                             }
                                         } else {
                                             return Err(Error::new(
                                                 meta.span(),
                                                 "abi must be a string",
-                                            )
+                                            ))
-                                            .to_compile_error())
                                         }
                                     } else {
                                         return Err(Error::new(
                                             meta.span(),
                                             format!("unrecognized {attr_name} parameter"),
-                                        )
+                                        ))
-                                        .to_compile_error())
                                     }
                                 }
                             }
@@ -105,7 +98,7 @@ pub fn derive_decode_impl_with_abi_type(
     input: &DeriveInput,
     trait_ident: Ident,
 ) -> Result<TokenStream, Error> {
-    let datatypes_array = utils::derive_abi_parameters_array(input, &trait_ident.to_string())?;
+    let datatypes_array = utils::abi_parameters_array(input, &trait_ident.to_string())?;
     Ok(derive_decode_impl(datatypes_array, trait_ident))
 }
 
@@ -117,18 +110,18 @@ pub fn derive_decode_impl_from_params(params: &[Param], trait_ident: Ident) -> T
 }
 
 pub fn derive_decode_impl(datatypes_array: TokenStream, trait_ident: Ident) -> TokenStream {
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
-    let contract_crate = ethers_contract_crate();
+    let ethers_contract = ethers_contract_crate();
     let data_types_init = quote! {let data_types = #datatypes_array;};
 
     quote! {
         let bytes = bytes.as_ref();
-        if bytes.len() < 4 || bytes[..4] != <Self as #contract_crate::#trait_ident>::selector() {
+        if bytes.len() < 4 || bytes[..4] != <Self as #ethers_contract::#trait_ident>::selector() {
-            return Err(#contract_crate::AbiError::WrongSelector);
+            return Err(#ethers_contract::AbiError::WrongSelector);
         }
         #data_types_init
-        let data_tokens = #core_crate::abi::decode(&data_types, &bytes[4..])?;
+        let data_tokens = #ethers_core::abi::decode(&data_types, &bytes[4..])?;
-        Ok(<Self as #core_crate::abi::Tokenizable>::from_token( #core_crate::abi::Token::Tuple(data_tokens))?)
+        Ok(<Self as #ethers_core::abi::Tokenizable>::from_token(#ethers_core::abi::Token::Tuple(data_tokens))?)
     }
 }
 
@@ -137,25 +130,24 @@ pub fn derive_codec_impls(
     input: &DeriveInput,
     decode_impl: TokenStream,
     trait_ident: Ident,
-) -> TokenStream {
+) -> Result<TokenStream, Error> {
     // the ethers crates to use
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
-    let contract_crate = ethers_contract_crate();
+    let ethers_contract = ethers_contract_crate();
     let struct_name = &input.ident;
 
     let codec_impl = quote! {
-
+        impl #ethers_core::abi::AbiDecode for #struct_name {
-        impl #core_crate::abi::AbiDecode for #struct_name {
+            fn decode(bytes: impl AsRef<[u8]>) -> ::std::result::Result<Self, #ethers_core::abi::AbiError> {
-            fn decode(bytes: impl AsRef<[u8]>) -> ::std::result::Result<Self, #core_crate::abi::AbiError> {
                 #decode_impl
             }
         }
 
-        impl #core_crate::abi::AbiEncode for #struct_name {
+        impl #ethers_core::abi::AbiEncode for #struct_name {
             fn encode(self) -> ::std::vec::Vec<u8> {
-                let tokens =  #core_crate::abi::Tokenize::into_tokens(self);
+                let tokens =  #ethers_core::abi::Tokenize::into_tokens(self);
-                let selector = <Self as #contract_crate::#trait_ident>::selector();
+                let selector = <Self as #ethers_contract::#trait_ident>::selector();
-                let encoded = #core_crate::abi::encode(&tokens);
+                let encoded = #ethers_core::abi::encode(&tokens);
                 selector
                     .iter()
                     .copied()
@@ -165,10 +157,10 @@ pub fn derive_codec_impls(
         }
 
     };
-    let tokenize_impl = abi_ty::derive_tokenizeable_impl(input);
+    let tokenize_impl = abi_ty::derive_tokenizeable_impl(input)?;
 
-    quote! {
+    Ok(quote! {
         #tokenize_impl
         #codec_impl
-    }
+    })
 }

ethers-contract/ethers-contract-derive/src/codec.rs

@@ -1,32 +1,32 @@
 //! Helper functions for deriving `EthAbiType`
 
 use ethers_core::macros::ethers_core_crate;
-
 use quote::quote;
 use syn::DeriveInput;
 
 /// Generates the `AbiEncode` + `AbiDecode` implementation
 pub fn derive_codec_impl(input: &DeriveInput) -> proc_macro2::TokenStream {
     let name = &input.ident;
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
 
     quote! {
-        impl  #core_crate::abi::AbiDecode for #name {
+        impl #ethers_core::abi::AbiDecode for #name {
-            fn decode(bytes: impl AsRef<[u8]>) -> ::std::result::Result<Self, #core_crate::abi::AbiError> {
+            fn decode(bytes: impl AsRef<[u8]>) -> ::std::result::Result<Self, #ethers_core::abi::AbiError> {
-                if let #core_crate::abi::ParamType::Tuple(params) = <Self as #core_crate::abi::AbiType>::param_type() {
+                if let #ethers_core::abi::ParamType::Tuple(params) = <Self as #ethers_core::abi::AbiType>::param_type() {
-                  let tokens = #core_crate::abi::decode(&params, bytes.as_ref())?;
+                    let tokens = #ethers_core::abi::decode(&params, bytes.as_ref())?;
-                  Ok(<Self as #core_crate::abi::Tokenizable>::from_token(#core_crate::abi::Token::Tuple(tokens))?)
+                    Ok(<Self as #ethers_core::abi::Tokenizable>::from_token(#ethers_core::abi::Token::Tuple(tokens))?)
                 } else {
                     Err(
-                        #core_crate::abi::InvalidOutputType("Expected tuple".to_string()).into()
+                        #ethers_core::abi::InvalidOutputType("Expected tuple".to_string()).into()
                     )
                 }
             }
         }
-        impl #core_crate::abi::AbiEncode for #name {
+
+        impl #ethers_core::abi::AbiEncode for #name {
             fn encode(self) -> ::std::vec::Vec<u8> {
-                let tokens =  #core_crate::abi::Tokenize::into_tokens(self);
+                let tokens = #ethers_core::abi::Tokenize::into_tokens(self);
-                #core_crate::abi::encode(&tokens)
+                #ethers_core::abi::encode(&tokens)
             }
         }
     }

ethers-contract/ethers-contract-derive/src/display.rs

@@ -1,22 +1,18 @@
 //! Helper functions for deriving `Display`
 
+use crate::utils;
+use ethers_core::{abi::ParamType, macros::ethers_core_crate};
 use proc_macro2::TokenStream;
 use quote::quote;
-use syn::{parse::Error, spanned::Spanned as _, Data, DeriveInput, Fields, Index};
+use syn::{parse::Error, spanned::Spanned, Data, DeriveInput, Fields, Index};
-
-use ethers_core::{abi::ParamType, macros::ethers_core_crate};
-
-use crate::utils;
 
 /// Derive `fmt::Display` for the given type
 pub(crate) fn derive_eth_display_impl(input: DeriveInput) -> Result<TokenStream, Error> {
-    let fields: Vec<_> = match input.data {
+    let fields = match input.data {
         Data::Struct(ref data) => match data.fields {
             Fields::Named(ref fields) => fields.named.iter().collect(),
             Fields::Unnamed(ref fields) => fields.unnamed.iter().collect(),
-            Fields::Unit => {
+            Fields::Unit => vec![],
-                vec![]
-            }
         },
         Data::Enum(_) => {
             return Err(Error::new(input.span(), "Enum types are not supported by EthDisplay"))
@@ -25,8 +21,10 @@ pub(crate) fn derive_eth_display_impl(input: DeriveInput) -> Result<TokenStream,
             return Err(Error::new(input.span(), "Union types are not supported by EthDisplay"))
         }
     };
-    let core_crate = ethers_core_crate();
+
-    let hex_encode = quote! {#core_crate::utils::hex::encode};
+    let ethers_core = ethers_core_crate();
+    let hex_encode = quote! {#ethers_core::utils::hex::encode};
+
     let mut fmts = TokenStream::new();
     for (idx, field) in fields.iter().enumerate() {
         let ident = field.ident.clone().map(|id| quote! {#id}).unwrap_or_else(|| {
@@ -92,6 +90,7 @@ pub(crate) fn derive_eth_display_impl(input: DeriveInput) -> Result<TokenStream,
             fmts.extend(quote! { write!(f, ", ")?;});
         }
     }
+
     let name = &input.ident;
     Ok(quote! {
         impl ::std::fmt::Display for #name {

ethers-contract/ethers-contract-derive/src/error.rs

@@ -10,46 +10,45 @@ use quote::quote;
 use syn::{parse::Error, DeriveInput};
 
 /// Generates the `EthError` trait support
-pub(crate) fn derive_eth_error_impl(input: DeriveInput) -> TokenStream {
+pub(crate) fn derive_eth_error_impl(input: DeriveInput) -> Result<TokenStream, Error> {
-    let attributes = match parse_calllike_attributes(&input, "etherror") {
+    let attributes = parse_calllike_attributes(&input, "etherror")?;
-        Ok(attributes) => attributes,
-        Err(errors) => return errors,
-    };
 
     let error_name = attributes.name.map(|(s, _)| s).unwrap_or_else(|| input.ident.to_string());
 
     let mut error = if let Some((src, span)) = attributes.abi {
         let raw_function_sig = src.trim_start_matches("error ").trim_start();
         // try to parse as solidity error
-        if let Ok(fun) = HumanReadableParser::parse_error(&src) {
+        match HumanReadableParser::parse_error(&src) {
-            fun
+            Ok(solidity_error) => solidity_error,
-        } else {
+            Err(parse_err) => {
-            // try to determine the abi by using its fields at runtime
                 return match derive_trait_impls_with_abi_type(
                     &input,
                     &error_name,
                     Some(raw_function_sig),
                 ) {
-                Ok(derived) => derived,
+                    Ok(derived) => Ok(derived),
                     Err(err) => {
-                    Error::new(span, format!("Unable to determine ABI for `{src}` : {err}"))
+                        Err(Error::new(span, format!("Unable to determine ABI for `{src}`: {err}")))
-                        .to_compile_error()
+                    }
+                    .map_err(|e| {
+                        let mut error = Error::new(span, parse_err);
+                        error.combine(Error::new(span, e));
+                        error
+                    }),
                 }
             }
         }
     } else {
         // try to determine the abi by using its fields at runtime
-        return match derive_trait_impls_with_abi_type(&input, &error_name, None) {
+        return derive_trait_impls_with_abi_type(&input, &error_name, None)
-            Ok(derived) => derived,
-            Err(err) => err.to_compile_error(),
-        }
     };
     error.name = error_name.clone();
-    let abi = error.abi_signature();
+
+    let sig = error.abi_signature();
     let selector = utils::selector(error.selector());
     let decode_impl = derive_decode_impl_from_params(&error.inputs, ident("EthError"));
 
-    derive_trait_impls(&input, &error_name, quote! {#abi.into()}, Some(selector), decode_impl)
+    derive_trait_impls(&input, &error_name, quote!(#sig.into()), Some(selector), decode_impl)
 }
 
 /// Use the `AbiType` trait to determine the correct `ParamType` and signature at runtime
@@ -58,17 +57,14 @@ fn derive_trait_impls_with_abi_type(
     function_call_name: &str,
     abi_signature: Option<&str>,
 ) -> Result<TokenStream, Error> {
-    let abi_signature = if let Some(abi) = abi_signature {
+    let mut abi_signature = if let Some(sig) = abi_signature {
-        quote! {#abi}
+        quote!(#sig)
     } else {
-        utils::derive_abi_signature_with_abi_type(input, function_call_name, "EthError")?
+        utils::abi_signature_with_abi_type(input, function_call_name, "EthError")?
-    };
-
-    let abi_signature = quote! {
-         #abi_signature.into()
     };
+    abi_signature.extend(quote!(.into()));
     let decode_impl = derive_decode_impl_with_abi_type(input, ident("EthError"))?;
-    Ok(derive_trait_impls(input, function_call_name, abi_signature, None, decode_impl))
+    derive_trait_impls(input, function_call_name, abi_signature, None, decode_impl)
 }
 
 /// Generates the EthError implementation
@@ -78,26 +74,25 @@ pub fn derive_trait_impls(
     abi_signature: TokenStream,
     selector: Option<TokenStream>,
     decode_impl: TokenStream,
-) -> TokenStream {
+) -> Result<TokenStream, Error> {
     // the ethers crates to use
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
-    let contract_crate = ethers_contract_crate();
+    let ethers_contract = ethers_contract_crate();
     let struct_name = &input.ident;
 
     let selector = selector.unwrap_or_else(|| {
         quote! {
-             #core_crate::utils::id(Self::abi_signature())
+            #ethers_core::utils::id(Self::abi_signature())
         }
     });
 
     let etherror_impl = quote! {
-        impl #contract_crate::EthError for #struct_name {
+        impl #ethers_contract::EthError for #struct_name {
-
             fn error_name() -> ::std::borrow::Cow<'static, str> {
                 #function_call_name.into()
             }
 
-            fn selector() -> #core_crate::types::Selector {
+            fn selector() -> #ethers_core::types::Selector {
                 #selector
             }
 
@@ -105,12 +100,11 @@ pub fn derive_trait_impls(
                 #abi_signature
             }
         }
-
     };
-    let codec_impl = derive_codec_impls(input, decode_impl, ident("EthError"));
+    let codec_impl = derive_codec_impls(input, decode_impl, ident("EthError"))?;
 
-    quote! {
+    Ok(quote! {
         #etherror_impl
         #codec_impl
-    }
+    })
 }

ethers-contract/ethers-contract-derive/src/event.rs

@@ -4,7 +4,7 @@ use ethers_contract_abigen::Source;
 use proc_macro2::{Span, TokenStream};
 use quote::quote;
 use syn::{
-    parse::Error, spanned::Spanned as _, AttrStyle, Data, DeriveInput, Field, Fields, Lit, Meta,
+    parse::Error, spanned::Spanned, AttrStyle, Data, DeriveInput, Field, Fields, Lit, Meta,
     NestedMeta,
 };
 
@@ -42,8 +42,9 @@ pub(crate) fn derive_eth_event_impl(input: DeriveInput) -> Result<TokenStream, E
                     }
                     Err(source_err) => {
                         // Return both error messages
-                        let message = format!("Failed parsing ABI: {parse_err} ({source_err})");
+                        let mut error = Error::new(span, parse_err);
-                        Err(Error::new(span, message))
+                        error.combine(Error::new(span, source_err));
+                        Err(error)
                     }
                 }
             }
@@ -102,7 +103,7 @@ pub(crate) fn derive_eth_event_impl(input: DeriveInput) -> Result<TokenStream, E
         }
     };
 
-    let tokenize_impl = abi_ty::derive_tokenizeable_impl(&input);
+    let tokenize_impl = abi_ty::derive_tokenizeable_impl(&input)?;
 
     Ok(quote! {
         #tokenize_impl

ethers-contract/ethers-contract-derive/src/lib.rs

@@ -112,7 +112,11 @@ pub fn abigen(input: TokenStream) -> TokenStream {
 #[proc_macro_derive(EthAbiType)]
 pub fn derive_abi_type(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-    TokenStream::from(abi_ty::derive_tokenizeable_impl(&input))
+    match abi_ty::derive_tokenizeable_impl(&input) {
+        Ok(tokens) => tokens,
+        Err(err) => err.to_compile_error(),
+    }
+    .into()
 }
 
 /// Derives the `AbiEncode`, `AbiDecode` and traits for the labeled type.
@@ -174,9 +178,10 @@ pub fn derive_abi_codec(input: TokenStream) -> TokenStream {
 pub fn derive_eth_display(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
     match display::derive_eth_display_impl(input) {
-        Ok(tokens) => TokenStream::from(tokens),
+        Ok(tokens) => tokens,
-        Err(err) => err.to_compile_error().into(),
+        Err(err) => err.to_compile_error(),
     }
+    .into()
 }
 
 /// Derives the `EthEvent` and `Tokenizeable` trait for the labeled type.
@@ -225,9 +230,10 @@ pub fn derive_eth_display(input: TokenStream) -> TokenStream {
 pub fn derive_abi_event(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
     match event::derive_eth_event_impl(input) {
-        Ok(tokens) => TokenStream::from(tokens),
+        Ok(tokens) => tokens,
-        Err(err) => err.to_compile_error().into(),
+        Err(err) => err.to_compile_error(),
     }
+    .into()
 }
 
 /// Derives the `EthCall` and `Tokenizeable` trait for the labeled type.
@@ -291,7 +297,11 @@ pub fn derive_abi_event(input: TokenStream) -> TokenStream {
 #[proc_macro_derive(EthCall, attributes(ethcall))]
 pub fn derive_abi_call(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-    TokenStream::from(call::derive_eth_call_impl(input))
+    match call::derive_eth_call_impl(input) {
+        Ok(tokens) => tokens,
+        Err(err) => err.to_compile_error(),
+    }
+    .into()
 }
 
 /// Derives the `EthError` and `Tokenizeable` trait for the labeled type.
@@ -328,5 +338,9 @@ pub fn derive_abi_call(input: TokenStream) -> TokenStream {
 #[proc_macro_derive(EthError, attributes(etherror))]
 pub fn derive_abi_error(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
-    TokenStream::from(error::derive_eth_error_impl(input))
+    match error::derive_eth_error_impl(input) {
+        Ok(tokens) => tokens,
+        Err(err) => err.to_compile_error(),
+    }
+    .into()
 }

ethers-contract/ethers-contract-derive/src/utils.rs

@@ -1,8 +1,8 @@
 use ethers_core::{abi::ParamType, macros::ethers_core_crate, types::Selector};
-use proc_macro2::{Ident, Literal, Span};
+use proc_macro2::{Ident, Literal, Span, TokenStream};
 use quote::{quote, quote_spanned};
 use syn::{
-    parse::Error, spanned::Spanned as _, Data, DeriveInput, Expr, Fields, GenericArgument, Lit,
+    parse::Error, spanned::Spanned, Data, DeriveInput, Expr, Fields, GenericArgument, Lit,
     PathArguments, Type,
 };
 
@@ -10,26 +10,29 @@ pub fn ident(name: &str) -> Ident {
     Ident::new(name, Span::call_site())
 }
 
-pub fn signature(hash: &[u8]) -> proc_macro2::TokenStream {
+pub fn signature(hash: &[u8]) -> TokenStream {
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
     let bytes = hash.iter().copied().map(Literal::u8_unsuffixed);
-    quote! {#core_crate::types::H256([#( #bytes ),*])}
+    quote! {#ethers_core::types::H256([#( #bytes ),*])}
 }
 
-pub fn selector(selector: Selector) -> proc_macro2::TokenStream {
+pub fn selector(selector: Selector) -> TokenStream {
     let bytes = selector.iter().copied().map(Literal::u8_unsuffixed);
     quote! {[#( #bytes ),*]}
 }
 
 /// Parses an int type from its string representation
 pub fn parse_int_param_type(s: &str) -> Option<ParamType> {
-    let size = s.chars().skip(1).collect::<String>().parse::<usize>().ok()?;
+    match s.chars().next() {
-    if s.starts_with('u') {
+        Some(c @ 'u') | Some(c @ 'i') => {
+            let size = s[1..].parse::<usize>().ok()?;
+            if c == 'u' {
                 Some(ParamType::Uint(size))
-    } else if s.starts_with('i') {
-        Some(ParamType::Int(size))
             } else {
-        None
+                Some(ParamType::Int(size))
+            }
+        }
+        _ => None,
     }
 }
 
@@ -37,64 +40,58 @@ pub fn parse_int_param_type(s: &str) -> Option<ParamType> {
 // This applies to strings, arrays, structs and bytes to follow the encoding of
 // these indexed param types according to
 // <https://solidity.readthedocs.io/en/develop/abi-spec.html#encoding-of-indexed-event-parameters>
-pub fn topic_param_type_quote(kind: &ParamType) -> proc_macro2::TokenStream {
+pub fn topic_param_type_quote(kind: &ParamType) -> TokenStream {
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
     match kind {
         ParamType::String |
         ParamType::Bytes |
         ParamType::Array(_) |
         ParamType::FixedArray(_, _) |
-        ParamType::Tuple(_) => quote! {#core_crate::abi::ParamType::FixedBytes(32)},
+        ParamType::Tuple(_) => quote! {#ethers_core::abi::ParamType::FixedBytes(32)},
         ty => param_type_quote(ty),
     }
 }
 
 /// Returns the rust type for the given parameter
-pub fn param_type_quote(kind: &ParamType) -> proc_macro2::TokenStream {
+pub fn param_type_quote(kind: &ParamType) -> TokenStream {
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
     match kind {
         ParamType::Address => {
-            quote! {#core_crate::abi::ParamType::Address}
+            quote! {#ethers_core::abi::ParamType::Address}
         }
         ParamType::Bytes => {
-            quote! {#core_crate::abi::ParamType::Bytes}
+            quote! {#ethers_core::abi::ParamType::Bytes}
         }
         ParamType::Int(size) => {
             let size = Literal::usize_suffixed(*size);
-            quote! {#core_crate::abi::ParamType::Int(#size)}
+            quote! {#ethers_core::abi::ParamType::Int(#size)}
         }
         ParamType::Uint(size) => {
             let size = Literal::usize_suffixed(*size);
-            quote! {#core_crate::abi::ParamType::Uint(#size)}
+            quote! {#ethers_core::abi::ParamType::Uint(#size)}
         }
         ParamType::Bool => {
-            quote! {#core_crate::abi::ParamType::Bool}
+            quote! {#ethers_core::abi::ParamType::Bool}
         }
         ParamType::String => {
-            quote! {#core_crate::abi::ParamType::String}
+            quote! {#ethers_core::abi::ParamType::String}
         }
         ParamType::Array(ty) => {
             let ty = param_type_quote(ty);
-            quote! {#core_crate::abi::ParamType::Array(Box::new(#ty))}
+            quote! {#ethers_core::abi::ParamType::Array(Box::new(#ty))}
         }
         ParamType::FixedBytes(size) => {
             let size = Literal::usize_suffixed(*size);
-            quote! {#core_crate::abi::ParamType::FixedBytes(#size)}
+            quote! {#ethers_core::abi::ParamType::FixedBytes(#size)}
         }
         ParamType::FixedArray(ty, size) => {
             let ty = param_type_quote(ty);
             let size = Literal::usize_suffixed(*size);
-            quote! {#core_crate::abi::ParamType::FixedArray(Box::new(#ty),#size)}
+            quote! {#ethers_core::abi::ParamType::FixedArray(Box::new(#ty), #size)}
         }
         ParamType::Tuple(tuple) => {
             let elements = tuple.iter().map(param_type_quote);
-            quote! {
+            quote!(#ethers_core::abi::ParamType::Tuple(::std::vec![#( #elements ),*]))
-                #core_crate::abi::ParamType::Tuple(
-                    ::std::vec![
-                        #( #elements ),*
-                    ]
-                )
-            }
         }
     }
 }
@@ -120,8 +117,8 @@ pub fn find_parameter_type(ty: &Type) -> Result<ParamType, Error> {
                 if let PathArguments::AngleBracketed(ref args) = ty.path.segments[0].arguments {
                     if args.args.len() == 1 {
                         if let GenericArgument::Type(ref ty) = args.args.iter().next().unwrap() {
-                            let kind = find_parameter_type(ty)?;
+                            return find_parameter_type(ty)
-                            return Ok(ParamType::Array(Box::new(kind)))
+                                .map(|kind| ParamType::Array(Box::new(kind)))
                         }
                     }
                 }
@@ -148,10 +145,12 @@ pub fn find_parameter_type(ty: &Type) -> Result<ParamType, Error> {
             }
             Err(Error::new(ty.span(), "Failed to derive proper ABI from fields"))
         }
-        Type::Tuple(ty) => {
+        Type::Tuple(ty) => ty
-            let params = ty.elems.iter().map(find_parameter_type).collect::<Result<Vec<_>, _>>()?;
+            .elems
-            Ok(ParamType::Tuple(params))
+            .iter()
-        }
+            .map(find_parameter_type)
+            .collect::<Result<Vec<_>, _>>()
+            .map(ParamType::Tuple),
         _ => Err(Error::new(ty.span(), "Failed to derive proper ABI from fields")),
     }
 }
@@ -200,22 +199,22 @@ pub fn derive_abi_inputs_from_fields(
 pub fn derive_param_type_with_abi_type(
     input: &DeriveInput,
     trait_name: &str,
-) -> Result<proc_macro2::TokenStream, Error> {
+) -> Result<TokenStream, Error> {
-    let core_crate = ethers_core_crate();
+    let ethers_core = ethers_core_crate();
-    let params = derive_abi_parameters_array(input, trait_name)?;
+    let params = abi_parameters_array(input, trait_name)?;
     Ok(quote! {
-        #core_crate::abi::ParamType::Tuple(::std::vec!#params)
+        #ethers_core::abi::ParamType::Tuple(::std::vec!#params)
     })
 }
 
 /// Use `AbiType::param_type` fo each field to construct the whole signature `<name>(<params,>*)` as
-/// `String`
+/// `String`.
-pub fn derive_abi_signature_with_abi_type(
+pub fn abi_signature_with_abi_type(
     input: &DeriveInput,
     function_name: &str,
     trait_name: &str,
-) -> Result<proc_macro2::TokenStream, Error> {
+) -> Result<TokenStream, Error> {
-    let params = derive_abi_parameters_array(input, trait_name)?;
+    let params = abi_parameters_array(input, trait_name)?;
     Ok(quote! {
         {
             let params: String = #params
@@ -231,30 +230,13 @@ pub fn derive_abi_signature_with_abi_type(
 
 /// Use `AbiType::param_type` fo each field to construct the signature's parameters as runtime array
 /// `[param1, param2,...]`
-pub fn derive_abi_parameters_array(
+pub fn abi_parameters_array(input: &DeriveInput, trait_name: &str) -> Result<TokenStream, Error> {
-    input: &DeriveInput,
+    let ethers_core = ethers_core_crate();
-    trait_name: &str,
-) -> Result<proc_macro2::TokenStream, Error> {
-    let core_crate = ethers_core_crate();
 
-    let param_types: Vec<_> = match input.data {
+    let fields = match input.data {
         Data::Struct(ref data) => match data.fields {
-            Fields::Named(ref fields) => fields
+            Fields::Named(ref fields) => &fields.named,
-                .named
+            Fields::Unnamed(ref fields) => &fields.unnamed,
-                .iter()
-                .map(|f| {
-                    let ty = &f.ty;
-                    quote_spanned! { f.span() => <#ty as #core_crate::abi::AbiType>::param_type() }
-                })
-                .collect(),
-            Fields::Unnamed(ref fields) => fields
-                .unnamed
-                .iter()
-                .map(|f| {
-                    let ty = &f.ty;
-                    quote_spanned! { f.span() => <#ty as #core_crate::abi::AbiType>::param_type() }
-                })
-                .collect(),
             Fields::Unit => {
                 return Err(Error::new(
                     input.span(),
@@ -276,7 +258,12 @@ pub fn derive_abi_parameters_array(
         }
     };
 
+    let iter = fields.iter().map(|f| {
+        let ty = &f.ty;
+        quote_spanned!(f.span() => <#ty as #ethers_core::abi::AbiType>::param_type())
+    });
+
     Ok(quote! {
-        [#( #param_types ),*]
+        [#( #iter ),*]
     })
 }