feat: function call enums EthCall macro and more (#517)

* fix: do not sort event variants

* style: use deref over clone

* style: refactor some stuff

* feat: add ethcall trait

* feat: include in abigen

* feat: add bare bones eth call derive

* feat: impl EthCall derive

* feat: support enums

* feat: use abigen enum derive

* fix: concrete abi and map errors

* test: first call test

* rustfmt

* chore: use correct trait name on error

* feat: derive display for call structs

* feat: add from conversion

* test: add convert test

* chore: docs and test

* chore: update changelog

* cargo fix

* feat: add unit type derive support and more test

* chore: patch ethabi

* chore: rm ethabi patch

* feat: add encode/decode trait impls

* style: use AsRef<[u8]>

* Update ethers-contract/ethers-contract-abigen/src/contract/methods.rs

Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>

* style: reindent macro body

* test: add tuple event test

Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Unreleased
 
+- add `EthCall` trait and derive macro which generates matching structs for contract calls [#517](https://github.com/gakonst/ethers-rs/pull/517)
 - `abigen!` now generates `Display` for all events using the new `EthDisplay` macro [#513](https://github.com/gakonst/ethers-rs/pull/513)
 - `abigen!` now supports overloaded functions natively [#501](https://github.com/gakonst/ethers-rs/pull/501)
 - `abigen!` now supports multiple contracts [#498](https://github.com/gakonst/ethers-rs/pull/498)

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

@@ -29,6 +29,8 @@ pub struct ExpandedContract {
     pub contract: TokenStream,
     /// All event impls of the contract
     pub events: TokenStream,
+    /// All contract call struct related types
+    pub call_structs: TokenStream,
     /// The contract's internal structs
     pub abi_structs: TokenStream,
 }
@@ -41,6 +43,7 @@ impl ExpandedContract {
             imports,
             contract,
             events,
+            call_structs,
             abi_structs,
         } = self;
         quote! {
@@ -52,6 +55,7 @@ impl ExpandedContract {
                 #imports
                 #contract
                 #events
+                #call_structs
                 #abi_structs
             }
         }
@@ -111,8 +115,8 @@ impl Context {
         // 3. impl block for the event functions
         let contract_events = self.event_methods()?;
 
-        // 4. impl block for the contract methods
+        // 4. impl block for the contract methods and their corresponding types
-        let contract_methods = self.methods()?;
+        let (contract_methods, call_structs) = self.methods_and_call_structs()?;
 
         // 5. Declare the structs parsed from the human readable abi
         let abi_structs_decl = self.abi_structs()?;
@@ -146,6 +150,7 @@ impl Context {
             imports,
             contract,
             events: events_decl,
+            call_structs,
             abi_structs: abi_structs_decl,
         })
     }

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

@@ -5,7 +5,6 @@ use inflector::Inflector;
 use proc_macro2::{Ident, Literal, TokenStream};
 use quote::quote;
 use std::collections::BTreeMap;
-use syn::Path;
 
 impl Context {
     /// Expands each event to a struct + its impl Detokenize block
@@ -33,9 +32,10 @@ impl Context {
 
     /// Generate the event filter methods for the contract
     pub fn event_methods(&self) -> Result<TokenStream> {
-        let sorted_events: BTreeMap<_, _> = self.abi.events.clone().into_iter().collect();
+        let sorted_events: BTreeMap<_, _> = self.abi.events.iter().collect();
         let filter_methods = sorted_events
             .values()
+            .map(std::ops::Deref::deref)
             .flatten()
             .map(|event| self.expand_filter(event))
             .collect::<Vec<_>>();
@@ -51,9 +51,9 @@ impl Context {
 
     /// Generate an enum with a variant for each event
     fn expand_events_enum(&self) -> TokenStream {
-        let sorted_events: BTreeMap<_, _> = self.abi.events.clone().into_iter().collect();
+        let variants = self
-
+            .abi
-        let variants = sorted_events
+            .events
             .values()
             .flatten()
             .map(|e| expand_struct_name(e, self.event_aliases.get(&e.abi_signature()).cloned()))
@@ -65,33 +65,11 @@ impl Context {
         let ethers_contract = util::ethers_contract_crate();
 
         quote! {
-            #[derive(Debug, Clone, PartialEq, Eq)]
+            #[derive(Debug, Clone, PartialEq, Eq, #ethers_contract::EthAbiType)]
             pub enum #enum_name {
                 #(#variants(#variants)),*
             }
 
-             impl #ethers_core::abi::Tokenizable for #enum_name {
-
-                 fn from_token(token: #ethers_core::abi::Token) -> Result<Self, #ethers_core::abi::InvalidOutputType> where
-                     Self: Sized {
-                    #(
-                        if let Ok(decoded) = #variants::from_token(token.clone()) {
-                            return Ok(#enum_name::#variants(decoded))
-                        }
-                    )*
-                    Err(#ethers_core::abi::InvalidOutputType("Failed to decode all event variants".to_string()))
-                }
-
-                fn into_token(self) -> #ethers_core::abi::Token {
-                    match self {
-                        #(
-                            #enum_name::#variants(element) => element.into_token()
-                        ),*
-                    }
-                }
-             }
-             impl #ethers_core::abi::TokenizableItem for #enum_name { }
-
              impl #ethers_contract::EthLogDecode for #enum_name {
                 fn decode_log(log: &#ethers_core::abi::RawLog) -> Result<Self, #ethers_core::abi::Error>
                 where
@@ -153,8 +131,8 @@ impl Context {
 
     /// Expands an event property type.
     ///
-    /// Note that this is slightly different than an expanding a Solidity type as
+    /// Note that this is slightly different from expanding a Solidity type as
-    /// complex types like arrays and strings get emited as hashes when they are
+    /// complex types like arrays and strings get emitted as hashes when they are
     /// indexed.
     /// If a complex types matches with a struct previously parsed by the AbiParser,
     /// we can replace it
@@ -213,8 +191,8 @@ impl Context {
         })
     }
 
-    /// Expands an ABI event into name-type pairs for each of its parameters.
+    /// Expands the name-type pairs for the given inputs
-    fn expand_params(&self, event: &Event) -> Result<Vec<(TokenStream, TokenStream, bool)>> {
+    fn expand_event_params(&self, event: &Event) -> Result<Vec<(TokenStream, TokenStream, bool)>> {
         event
             .inputs
             .iter()
@@ -264,7 +242,7 @@ impl Context {
 
         let event_name = expand_struct_name(event, sig);
 
-        let params = self.expand_params(event)?;
+        let params = self.expand_event_params(event)?;
         // expand as a tuple if all fields are anonymous
         let all_anonymous_fields = event.inputs.iter().all(|input| input.name.is_empty());
         let data_type_definition = if all_anonymous_fields {
@@ -273,7 +251,7 @@ impl Context {
             expand_data_struct(&event_name, &params)
         };
 
-        let derives = expand_derives(&self.event_derives);
+        let derives = util::expand_derives(&self.event_derives);
 
         let ethers_contract = util::ethers_contract_crate();
 
@@ -323,16 +301,20 @@ fn expand_data_struct(name: &Ident, params: &[(TokenStream, TokenStream, bool)])
 fn expand_data_tuple(name: &Ident, params: &[(TokenStream, TokenStream, bool)]) -> TokenStream {
     let fields = params
         .iter()
-        .map(|(_, ty, _)| quote! { pub #ty })
+        .map(|(_, ty, indexed)| {
+            if *indexed {
+                quote! {
+                #[ethevent(indexed)] pub #ty }
+            } else {
+                quote! {
+                pub #ty }
+            }
+        })
         .collect::<Vec<_>>();
 
     quote! { struct #name( #( #fields ),* ); }
 }
 
-fn expand_derives(derives: &[Path]) -> TokenStream {
-    quote! {#(#derives),*}
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -450,7 +432,7 @@ mod tests {
         };
 
         let cx = test_context();
-        let params = cx.expand_params(&event).unwrap();
+        let params = cx.expand_event_params(&event).unwrap();
         let name = expand_struct_name(&event, None);
         let definition = expand_data_struct(&name, &params);
 
@@ -482,7 +464,7 @@ mod tests {
         };
 
         let cx = test_context_with_alias("Foo(bool,address)", "FooAliased");
-        let params = cx.expand_params(&event).unwrap();
+        let params = cx.expand_event_params(&event).unwrap();
         let alias = Some(util::ident("FooAliased"));
         let name = expand_struct_name(&event, alias);
         let definition = expand_data_struct(&name, &params);
@@ -515,7 +497,7 @@ mod tests {
         };
 
         let cx = test_context();
-        let params = cx.expand_params(&event).unwrap();
+        let params = cx.expand_event_params(&event).unwrap();
         let name = expand_struct_name(&event, None);
         let definition = expand_data_tuple(&name, &params);
 
@@ -544,7 +526,7 @@ mod tests {
         };
 
         let cx = test_context_with_alias("Foo(bool,address)", "FooAliased");
-        let params = cx.expand_params(&event).unwrap();
+        let params = cx.expand_event_params(&event).unwrap();
         let alias = Some(util::ident("FooAliased"));
         let name = expand_struct_name(&event, alias);
         let definition = expand_data_tuple(&name, &params);

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

@@ -18,32 +18,162 @@ use super::{types, util, Context};
 /// to the Solidity contract methods.
 impl Context {
     /// Expands all method implementations
-    pub(crate) fn methods(&self) -> Result<TokenStream> {
+    pub(crate) fn methods_and_call_structs(&self) -> Result<(TokenStream, TokenStream)> {
-        let mut aliases = self.get_method_aliases()?;
+        let aliases = self.get_method_aliases()?;
-        let sorted_functions: BTreeMap<_, _> = self.abi.functions.clone().into_iter().collect();
+        let sorted_functions: BTreeMap<_, _> = self.abi.functions.iter().collect();
         let functions = sorted_functions
             .values()
+            .map(std::ops::Deref::deref)
             .flatten()
             .map(|function| {
                 let signature = function.abi_signature();
-                self.expand_function(function, aliases.remove(&signature))
+                self.expand_function(function, aliases.get(&signature).cloned())
                     .with_context(|| format!("error expanding function '{}'", signature))
             })
             .collect::<Result<Vec<_>>>()?;
 
-        Ok(quote! { #( #functions )* })
+        let function_impls = quote! { #( #functions )* };
+        let call_structs = self.expand_call_structs(aliases)?;
+
+        Ok((function_impls, call_structs))
     }
 
-    fn expand_inputs_call_arg_with_structs(
+    /// Expands to the corresponding struct type based on the inputs of the given function
+    fn expand_call_struct(
         &self,
-        fun: &Function,
+        function: &Function,
-    ) -> Result<(TokenStream, TokenStream)> {
+        alias: Option<&Ident>,
+    ) -> Result<TokenStream> {
+        let call_name = expand_call_struct_name(function, alias);
+        let fields = self.expand_input_pairs(function)?;
+        // expand as a tuple if all fields are anonymous
+        let all_anonymous_fields = function.inputs.iter().all(|input| input.name.is_empty());
+        let call_type_definition = if all_anonymous_fields {
+            // expand to a tuple struct
+            expand_data_tuple(&call_name, &fields)
+        } else {
+            // expand to a struct
+            expand_data_struct(&call_name, &fields)
+        };
+        let function_name = &function.name;
+        let abi_signature = function.abi_signature();
+        let doc = format!(
+            "Container type for all input parameters for the `{}`function with signature `{}` and selector `{:?}`",
+            function.name,
+            abi_signature,
+            function.selector()
+        );
+        let abi_signature_doc = util::expand_doc(&doc);
+        let ethers_contract = util::ethers_contract_crate();
+        // use the same derives as for events
+        let derives = util::expand_derives(&self.event_derives);
+
+        Ok(quote! {
+            #abi_signature_doc
+            #[derive(Clone, Debug, Default, Eq, PartialEq, #ethers_contract::EthCall, #ethers_contract::EthDisplay, #derives)]
+            #[ethcall( name = #function_name, abi = #abi_signature )]
+            pub #call_type_definition
+        })
+    }
+
+    /// Expands all structs
+    fn expand_call_structs(&self, aliases: BTreeMap<String, Ident>) -> Result<TokenStream> {
+        let mut struct_defs = Vec::new();
+        let mut struct_names = Vec::new();
+        let mut variant_names = Vec::new();
+
+        for function in self.abi.functions.values().flatten() {
+            let signature = function.abi_signature();
+            let alias = aliases.get(&signature);
+            struct_defs.push(self.expand_call_struct(function, alias)?);
+            struct_names.push(expand_call_struct_name(function, alias));
+            variant_names.push(expand_call_struct_variant_name(function, alias));
+        }
+
+        let struct_def_tokens = quote! {
+            #(#struct_defs)*
+        };
+
+        if struct_defs.len() <= 1 {
+            // no need for an enum
+            return Ok(struct_def_tokens);
+        }
+
+        let ethers_core = util::ethers_core_crate();
+        let ethers_contract = util::ethers_contract_crate();
+
+        let enum_name = self.expand_calls_enum_name();
+        Ok(quote! {
+            #struct_def_tokens
+
+           #[derive(Debug, Clone, PartialEq, Eq, #ethers_contract::EthAbiType)]
+            pub enum #enum_name {
+                #(#variant_names(#struct_names)),*
+            }
+
+        impl  #ethers_contract::AbiDecode for #enum_name {
+            fn decode(data: impl AsRef<[u8]>) -> Result<Self, #ethers_contract::AbiError> {
+                 #(
+                    if let Ok(decoded) = <#struct_names as #ethers_contract::AbiDecode>::decode(data.as_ref()) {
+                        return Ok(#enum_name::#variant_names(decoded))
+                    }
+                )*
+                Err(#ethers_core::abi::Error::InvalidData.into())
+            }
+        }
+
+         impl  #ethers_contract::AbiEncode for #enum_name {
+            fn encode(self) -> Result<#ethers_core::types::Bytes, #ethers_contract::AbiError> {
+                match self {
+                    #(
+                        #enum_name::#variant_names(element) => element.encode()
+                    ),*
+                }
+            }
+        }
+
+        impl ::std::fmt::Display for #enum_name {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
+                match self {
+                    #(
+                        #enum_name::#variant_names(element) => element.fmt(f)
+                    ),*
+                }
+            }
+        }
+
+        #(
+            impl ::std::convert::From<#struct_names> for #enum_name {
+                fn from(var: #struct_names) -> Self {
+                    #enum_name::#variant_names(var)
+                }
+            }
+        )*
+
+        })
+    }
+
+    /// The name ident of the calls enum
+    fn expand_calls_enum_name(&self) -> Ident {
+        util::ident(&format!("{}Calls", self.contract_name.to_string()))
+    }
+
+    /// Expands to the `name : type` pairs of the function's inputs
+    fn expand_input_pairs(&self, fun: &Function) -> Result<Vec<(TokenStream, TokenStream)>> {
         let mut args = Vec::with_capacity(fun.inputs.len());
-        let mut call_args = Vec::with_capacity(fun.inputs.len());
+        for (idx, param) in fun.inputs.iter().enumerate() {
-        for (i, param) in fun.inputs.iter().enumerate() {
+            let name = util::expand_input_name(idx, &param.name);
-            let name = util::expand_input_name(i, &param.name);
             let ty = self.expand_input_param(fun, &param.name, &param.kind)?;
-            args.push(quote! { #name: #ty });
+            args.push((name, ty));
+        }
+        Ok(args)
+    }
+
+    /// Expands the arguments for the call that eventually calls the contract
+    fn expand_contract_call_args(&self, fun: &Function) -> Result<TokenStream> {
+        let mut call_args = Vec::with_capacity(fun.inputs.len());
+        for (idx, param) in fun.inputs.iter().enumerate() {
+            let name = util::expand_input_name(idx, &param.name);
             let call_arg = match param.kind {
                 // this is awkward edge case where the function inputs are a single struct
                 // we need to force this argument into a tuple so it gets expanded to `((#name,))`
@@ -59,14 +189,13 @@ impl Context {
             };
             call_args.push(call_arg);
         }
-        let args = quote! { #( , #args )* };
         let call_args = match call_args.len() {
             0 => quote! { () },
             1 => quote! { #( #call_args )* },
             _ => quote! { ( #(#call_args, )* ) },
         };
 
-        Ok((args, call_args))
+        Ok(call_args)
     }
 
     fn expand_input_param(
@@ -111,13 +240,16 @@ impl Context {
         // TODO use structs
         let outputs = expand_fn_outputs(&function.outputs)?;
 
-        let _ethers_core = util::ethers_core_crate();
-        let _ethers_providers = util::ethers_providers_crate();
         let ethers_contract = util::ethers_contract_crate();
 
         let result = quote! { #ethers_contract::builders::ContractCall<M, #outputs> };
 
-        let (input, arg) = self.expand_inputs_call_arg_with_structs(function)?;
+        let contract_args = self.expand_contract_call_args(function)?;
+        let function_params = self
+            .expand_input_pairs(function)?
+            .into_iter()
+            .map(|(name, ty)| quote! { #name: #ty });
+        let function_params = quote! { #( , #function_params )* };
 
         let doc = util::expand_doc(&format!(
             "Calls the contract's `{}` (0x{}) function",
@@ -127,8 +259,8 @@ impl Context {
         Ok(quote! {
 
             #doc
-            pub fn #name(&self #input) -> #result {
+            pub fn #name(&self #function_params) -> #result {
-                self.0.method_hash(#selector, #arg)
+                self.0.method_hash(#selector, #contract_args)
                     .expect("method not found (this should never happen)")
             }
         })
@@ -227,6 +359,55 @@ fn expand_selector(selector: Selector) -> TokenStream {
     quote! { [#( #bytes ),*] }
 }
 
+/// Expands to the name of the call struct
+fn expand_call_struct_name(function: &Function, alias: Option<&Ident>) -> Ident {
+    let name = if let Some(id) = alias {
+        format!("{}Call", id.to_string().to_pascal_case())
+    } else {
+        format!("{}Call", function.name.to_pascal_case())
+    };
+    util::ident(&name)
+}
+
+/// Expands to the name of the call struct
+fn expand_call_struct_variant_name(function: &Function, alias: Option<&Ident>) -> Ident {
+    let name = if let Some(id) = alias {
+        id.to_string().to_pascal_case()
+    } else {
+        function.name.to_pascal_case()
+    };
+    util::ident(&name)
+}
+
+/// Expands to the tuple struct definition
+fn expand_data_tuple(name: &Ident, params: &[(TokenStream, TokenStream)]) -> TokenStream {
+    let fields = params
+        .iter()
+        .map(|(_, ty)| {
+            quote! {
+            pub #ty }
+        })
+        .collect::<Vec<_>>();
+
+    if fields.is_empty() {
+        quote! { struct #name; }
+    } else {
+        quote! { struct #name( #( #fields ),* ); }
+    }
+}
+
+/// Expands to the struct definition of a call struct
+fn expand_data_struct(name: &Ident, params: &[(TokenStream, TokenStream)]) -> TokenStream {
+    let fields = params
+        .iter()
+        .map(|(name, ty)| {
+            quote! { pub #name: #ty }
+        })
+        .collect::<Vec<_>>();
+
+    quote! { struct #name { #( #fields, )* } }
+}
+
 #[cfg(test)]
 mod tests {
     use ethers_core::abi::ParamType;

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

@@ -127,8 +127,7 @@ impl Context {
         let name = util::ident(name);
 
         // use the same derives as for events
-        let derives = &self.event_derives;
+        let derives = util::expand_derives(&self.event_derives);
-        let derives = quote! {#(#derives),*};
 
         let ethers_contract = util::ethers_contract_crate();
         Ok(quote! {

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

@@ -117,6 +117,10 @@ pub fn expand_doc(s: &str) -> TokenStream {
     }
 }
 
+pub fn expand_derives(derives: &[Path]) -> TokenStream {
+    quote! {#(#derives),*}
+}
+
 /// Parses the given address string
 pub fn parse_address<S>(address_str: S) -> Result<Address>
 where

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

@@ -1,9 +1,10 @@
 //! Helper functions for deriving `EthAbiType`
 
 use ethers_contract_abigen::ethers_core_crate;
+use proc_macro2::{Ident, TokenStream};
 use quote::{quote, quote_spanned};
 use syn::spanned::Spanned as _;
-use syn::{parse::Error, Data, DeriveInput, Fields};
+use syn::{parse::Error, Data, DeriveInput, Fields, Variant};
 
 /// Generates the tokenize implementation
 pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream {
@@ -80,17 +81,13 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
                     into_token_impl,
                 )
             }
-            Fields::Unit => {
+            Fields::Unit => return tokenize_unit_type(&input.ident),
-                return Error::new(
-                    input.span(),
-                    "EthAbiType cannot be derived for empty structs and unit",
-                )
-                .to_compile_error();
-            }
         },
-        Data::Enum(_) => {
+        Data::Enum(ref data) => {
-            return Error::new(input.span(), "EthAbiType cannot be derived for enums")
+            return match tokenize_enum(name, data.variants.iter()) {
-                .to_compile_error();
+                Ok(tokens) => tokens,
+                Err(err) => err.to_compile_error(),
+            }
         }
         Data::Union(_) => {
             return Error::new(input.span(), "EthAbiType cannot be derived for unions")
@@ -169,3 +166,86 @@ pub fn derive_tokenizeable_impl(input: &DeriveInput) -> proc_macro2::TokenStream
          { }
     }
 }
+
+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) -> Result<Self, #ethers_core::abi::InvalidOutputType> where
+                 Self: Sized {
+                if let #ethers_core::abi::Token::Tuple(tokens) = token {
+                    if !tokens.is_empty() {
+                         Err(#ethers_core::abi::InvalidOutputType(::std::format!(
+                        "Expected empty tuple, got {:?}",
+                        tokens
+                    )))
+                    } else {
+                        Ok(#name{})
+                    }
+                } else {
+                    Err(#ethers_core::abi::InvalidOutputType(::std::format!(
+                        "Expected Tuple, got {:?}",
+                        token
+                    )))
+                }
+            }
+
+            fn into_token(self) -> #ethers_core::abi::Token {
+               #ethers_core::abi::Token::Tuple(::std::vec::Vec::new())
+            }
+         }
+         impl #ethers_core::abi::TokenizableItem for #name { }
+    }
+}
+
+fn tokenize_enum<'a>(
+    enum_name: &Ident,
+    variants: impl Iterator<Item = &'a Variant> + 'a,
+) -> Result<TokenStream, Error> {
+    let ethers_core = ethers_core_crate();
+
+    let mut into_tokens = TokenStream::new();
+    let mut from_tokens = TokenStream::new();
+    for variant in variants {
+        if variant.fields.len() > 1 {
+            return Err(Error::new(
+                variant.span(),
+                "EthAbiType cannot be derived for enum variants with multiple fields",
+            ));
+        }
+        let var_ident = &variant.ident;
+        if let Some(field) = variant.fields.iter().next() {
+            let ty = &field.ty;
+            from_tokens.extend(quote! {
+                if let Ok(decoded) = #ty::from_token(token.clone()) {
+                    return Ok(#enum_name::#var_ident(decoded))
+                }
+            });
+            into_tokens.extend(quote! {
+                 #enum_name::#var_ident(element) => element.into_token(),
+            });
+        } else {
+            into_tokens.extend(quote! {
+                 #enum_name::#var_ident(element) => # ethers_core::abi::Token::Tuple(::std::vec::Vec::new()),
+            });
+        }
+    }
+
+    Ok(quote! {
+         impl #ethers_core::abi::Tokenizable for #enum_name {
+
+             fn from_token(token: #ethers_core::abi::Token) -> Result<Self, #ethers_core::abi::InvalidOutputType> where
+                 Self: Sized {
+                #from_tokens
+                Err(#ethers_core::abi::InvalidOutputType("Failed to decode all type variants".to_string()))
+            }
+
+            fn into_token(self) -> #ethers_core::abi::Token {
+                match self {
+                   #into_tokens
+                }
+            }
+         }
+         impl #ethers_core::abi::TokenizableItem for #enum_name { }
+    })
+}

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

@@ -0,0 +1,254 @@
+//! Helper functions for deriving `EthCall`
+
+use ethers_contract_abigen::{ethers_contract_crate, ethers_core_crate};
+use proc_macro2::{Span, TokenStream};
+use quote::quote;
+use syn::spanned::Spanned as _;
+use syn::{parse::Error, AttrStyle, DeriveInput, Lit, Meta, NestedMeta};
+
+use ethers_core::abi::{param_type::Reader, AbiParser, Function, FunctionExt, Param, ParamType};
+
+use crate::abi_ty;
+use crate::utils;
+
+/// Generates the `ethcall` trait support
+pub(crate) fn derive_eth_call_impl(input: DeriveInput) -> TokenStream {
+    // the ethers crates to use
+    let core_crate = ethers_core_crate();
+    let contract_crate = ethers_contract_crate();
+
+    let name = &input.ident;
+    let attributes = match parse_call_attributes(&input) {
+        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 {
+        // try to parse as solidity function
+        if let Ok(fun) = parse_function(&src) {
+            fun
+        } else {
+            // try as tuple
+            if let Some(inputs) = Reader::read(
+                src.trim_start_matches("function ")
+                    .trim_start()
+                    .trim_start_matches(&function_call_name),
+            )
+            .ok()
+            .and_then(|param| match param {
+                ParamType::Tuple(params) => Some(
+                    params
+                        .into_iter()
+                        .map(|kind| Param {
+                            name: "".to_string(),
+                            kind,
+                            internal_type: None,
+                        })
+                        .collect(),
+                ),
+                _ => None,
+            }) {
+                #[allow(deprecated)]
+                Function {
+                    name: function_call_name.clone(),
+                    inputs,
+                    outputs: vec![],
+                    constant: false,
+                    state_mutability: Default::default(),
+                }
+            } else {
+                return Error::new(span, format!("Unable to determine ABI: {}", src))
+                    .to_compile_error();
+            }
+        }
+    } else {
+        // // try to determine the abi from the fields
+        match derive_abi_function_from_fields(&input) {
+            Ok(event) => event,
+            Err(err) => return err.to_compile_error(),
+        }
+    };
+
+    function.name = function_call_name.clone();
+
+    let abi = function.abi_signature();
+    let selector = utils::selector(function.selector());
+
+    let decode_impl = derive_decode_impl(&function);
+
+    let ethcall_impl = quote! {
+        impl #contract_crate::EthCall for #name {
+
+            fn function_name() -> ::std::borrow::Cow<'static, str> {
+                #function_call_name.into()
+            }
+
+            fn selector() -> #core_crate::types::Selector {
+                #selector
+            }
+
+            fn abi_signature() -> ::std::borrow::Cow<'static, str> {
+                #abi.into()
+            }
+
+        }
+
+        impl  #contract_crate::AbiDecode for #name {
+            fn decode(bytes: impl AsRef<[u8]>) -> Result<Self, #contract_crate::AbiError> {
+                #decode_impl
+            }
+        }
+    };
+    let tokenize_impl = abi_ty::derive_tokenizeable_impl(&input);
+
+    quote! {
+        #tokenize_impl
+        #ethcall_impl
+    }
+}
+
+fn derive_decode_impl(function: &Function) -> TokenStream {
+    let core_crate = ethers_core_crate();
+    let contract_crate = ethers_contract_crate();
+    let data_types = function
+        .inputs
+        .iter()
+        .map(|input| utils::param_type_quote(&input.kind));
+
+    let data_types_init = quote! {let data_types = [#( #data_types ),*];};
+
+    quote! {
+        let bytes = bytes.as_ref();
+        if bytes.len() < 4 || bytes[..4] != <Self as #contract_crate::EthCall>::selector() {
+            return Err(#contract_crate::AbiError::WrongSelector);
+        }
+        #data_types_init
+        let data_tokens = #core_crate::abi::decode(&data_types, &bytes[4..])?;
+        Ok(<Self as #core_crate::abi::Tokenizable>::from_token( #core_crate::abi::Token::Tuple(data_tokens))?)
+    }
+}
+
+/// Determine the function's ABI by parsing the AST
+fn derive_abi_function_from_fields(input: &DeriveInput) -> Result<Function, Error> {
+    #[allow(deprecated)]
+    let function = Function {
+        name: "".to_string(),
+        inputs: utils::derive_abi_inputs_from_fields(input, "EthCall")?
+            .into_iter()
+            .map(|(name, kind)| Param {
+                name,
+                kind,
+                internal_type: None,
+            })
+            .collect(),
+        outputs: vec![],
+        constant: false,
+        state_mutability: Default::default(),
+    };
+    Ok(function)
+}
+
+/// All the attributes the `EthCall` macro supports
+#[derive(Default)]
+struct EthCallAttributes {
+    name: Option<(String, Span)>,
+    abi: Option<(String, Span)>,
+}
+
+/// extracts the attributes from the struct annotated with `EthCall`
+fn parse_call_attributes(input: &DeriveInput) -> Result<EthCallAttributes, TokenStream> {
+    let mut result = EthCallAttributes::default();
+    for a in input.attrs.iter() {
+        if let AttrStyle::Outer = a.style {
+            if let Ok(Meta::List(meta)) = a.parse_meta() {
+                if meta.path.is_ident("ethcall") {
+                    for n in meta.nested.iter() {
+                        if let NestedMeta::Meta(meta) = n {
+                            match meta {
+                                Meta::Path(path) => {
+                                    return Err(Error::new(
+                                        path.span(),
+                                        "unrecognized ethcall parameter",
+                                    )
+                                    .to_compile_error());
+                                }
+                                Meta::List(meta) => {
+                                    return Err(Error::new(
+                                        meta.path.span(),
+                                        "unrecognized ethcall parameter",
+                                    )
+                                    .to_compile_error());
+                                }
+                                Meta::NameValue(meta) => {
+                                    if meta.path.is_ident("name") {
+                                        if let Lit::Str(ref lit_str) = meta.lit {
+                                            if result.name.is_none() {
+                                                result.name =
+                                                    Some((lit_str.value(), lit_str.span()));
+                                            } else {
+                                                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 {
+                                            if result.abi.is_none() {
+                                                result.abi =
+                                                    Some((lit_str.value(), lit_str.span()));
+                                            } else {
+                                                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(),
+                                            "unrecognized ethcall parameter",
+                                        )
+                                        .to_compile_error());
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+    Ok(result)
+}
+
+fn parse_function(abi: &str) -> Result<Function, String> {
+    let abi = if !abi.trim_start().starts_with("function ") {
+        format!("function {}", abi)
+    } else {
+        abi.to_string()
+    };
+
+    AbiParser::default()
+        .parse_function(&abi)
+        .map_err(|err| format!("Failed to parse the function ABI: {:?}", err))
+}

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

@@ -133,7 +133,6 @@ pub(crate) fn derive_eth_event_impl(input: DeriveInput) -> TokenStream {
 
     let tokenize_impl = abi_ty::derive_tokenizeable_impl(&input);
 
-    // parse attributes abi into source
     quote! {
         #tokenize_impl
         #ethevent_impl
@@ -322,47 +321,11 @@ fn derive_decode_from_log_impl(
     })
 }
 
+/// Determine the event's ABI by parsing the AST
 fn derive_abi_event_from_fields(input: &DeriveInput) -> Result<Event, Error> {
-    let fields: Vec<_> = 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 => {
-                return Err(Error::new(
-                    input.span(),
-                    "EthEvent cannot be derived for empty structs and unit",
-                ))
-            }
-        },
-        Data::Enum(_) => {
-            return Err(Error::new(
-                input.span(),
-                "EthEvent cannot be derived for enums",
-            ));
-        }
-        Data::Union(_) => {
-            return Err(Error::new(
-                input.span(),
-                "EthEvent cannot be derived for unions",
-            ));
-        }
-    };
-
-    let inputs = fields
-        .iter()
-        .map(|f| {
-            let name = f
-                .ident
-                .as_ref()
-                .map(|name| name.to_string())
-                .unwrap_or_else(|| "".to_string());
-            utils::find_parameter_type(&f.ty).map(|ty| (name, ty))
-        })
-        .collect::<Result<Vec<_>, _>>()?;
-
     let event = Event {
         name: "".to_string(),
-        inputs: inputs
+        inputs: utils::derive_abi_inputs_from_fields(input, "EthEvent")?
             .into_iter()
             .map(|(name, kind)| EventParam {
                 name,

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

@@ -9,6 +9,7 @@ use abigen::Contracts;
 
 pub(crate) mod abi_ty;
 mod abigen;
+mod call;
 mod display;
 mod event;
 mod spanned;
@@ -111,6 +112,9 @@ pub fn derive_abi_type(input: TokenStream) -> TokenStream {
 /// # Example
 ///
 /// ```ignore
+/// use ethers_contract::EthDisplay;
+/// use ethers_core::types::*;
+///
 /// #[derive(Debug, Clone, EthAbiType, EthDisplay)]
 /// struct MyStruct {
 ///     addr: Address,
@@ -161,7 +165,8 @@ pub fn derive_eth_display(input: TokenStream) -> TokenStream {
 ///
 /// # Example
 /// ```ignore
-/// # use ethers_core::types::Address;
+/// use ethers_contract::EthCall;
+/// use ethers_core::types::Address;
 ///
 /// #[derive(Debug, EthAbiType)]
 /// struct Inner {
@@ -183,3 +188,70 @@ pub fn derive_abi_event(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
     TokenStream::from(event::derive_eth_event_impl(input))
 }
+
+/// Derives the `EthCall` and `Tokenizeable` trait for the labeled type.
+///
+/// Additional arguments can be specified using the `#[ethcall(...)]`
+/// attribute:
+///
+/// For the struct:
+///
+/// - `name`, `name = "..."`: Overrides the generated `EthCall` function name, default
+///   is the
+///  struct's name.
+/// - `abi`, `abi = "..."`: The ABI signature for the function this call's data
+///   corresponds to.
+///
+///  NOTE: in order to successfully parse the `abi` (`<name>(<args>,...)`) the `<name`>
+///   must match either the struct name or the name attribute: `#[ethcall(name ="<name>"]`
+///
+/// # Example
+///
+/// ```ignore
+/// use ethers_contract::EthCall;
+///
+/// #[derive(Debug, Clone, EthCall)]
+/// #[ethcall(name ="my_call")]
+/// struct MyCall {
+///     addr: Address,
+///     old_value: String,
+///     new_value: String,
+/// }
+/// assert_eq!(
+///     MyCall::abi_signature().as_ref(),
+///     "my_call(address,string,string)"
+/// );
+/// ```
+///
+/// # Example
+///
+/// Call with struct inputs
+///
+/// ```ignore
+/// use ethers_core::abi::Address;
+///
+/// #[derive(Debug, Clone, PartialEq, EthAbiType)]
+/// struct SomeType {
+///     inner: Address,
+///     msg: String,
+/// }
+///
+/// #[derive(Debug, PartialEq, EthCall)]
+/// #[ethcall(name = "foo", abi = "foo(address,(address,string),string)")]
+/// struct FooCall {
+///     old_author: Address,
+///     inner: SomeType,
+///     new_value: String,
+/// }
+///
+/// assert_eq!(
+///     FooCall::abi_signature().as_ref(),
+///     "foo(address,(address,string),string)"
+/// );
+/// ```
+///
+#[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))
+}

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

@@ -1,9 +1,12 @@
 use ethers_contract_abigen::ethers_core_crate;
 use ethers_core::abi::ParamType;
+use ethers_core::types::Selector;
 use proc_macro2::Literal;
 use quote::quote;
 use syn::spanned::Spanned as _;
-use syn::{parse::Error, Expr, GenericArgument, Lit, PathArguments, Type};
+use syn::{
+    parse::Error, Data, DeriveInput, Expr, Fields, GenericArgument, Lit, PathArguments, Type,
+};
 
 pub fn signature(hash: &[u8]) -> proc_macro2::TokenStream {
     let core_crate = ethers_core_crate();
@@ -11,6 +14,11 @@ pub fn signature(hash: &[u8]) -> proc_macro2::TokenStream {
     quote! {#core_crate::types::H256([#( #bytes ),*])}
 }
 
+pub fn selector(selector: Selector) -> proc_macro2::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
@@ -158,3 +166,49 @@ pub fn find_parameter_type(ty: &Type) -> Result<ParamType, Error> {
         )),
     }
 }
+
+/// Attempts to determine the ABI Paramtypes from the type's AST
+pub fn derive_abi_inputs_from_fields(
+    input: &DeriveInput,
+    trait_name: &str,
+) -> Result<Vec<(String, ParamType)>, Error> {
+    let fields: Vec<_> = 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 => {
+                return Err(Error::new(
+                    input.span(),
+                    format!(
+                        "{} cannot be derived for empty structs and unit",
+                        trait_name
+                    ),
+                ))
+            }
+        },
+        Data::Enum(_) => {
+            return Err(Error::new(
+                input.span(),
+                format!("{} cannot be derived for enums", trait_name),
+            ));
+        }
+        Data::Union(_) => {
+            return Err(Error::new(
+                input.span(),
+                format!("{} cannot be derived for unions", trait_name),
+            ));
+        }
+    };
+
+    fields
+        .iter()
+        .map(|f| {
+            let name = f
+                .ident
+                .as_ref()
+                .map(|name| name.to_string())
+                .unwrap_or_else(|| "".to_string());
+            find_parameter_type(&f.ty).map(|ty| (name, ty))
+        })
+        .collect()
+}

ethers-contract/src/call.rs

@@ -7,10 +7,43 @@ use ethers_core::{
 };
 use ethers_providers::{Middleware, PendingTransaction, ProviderError};
 
+use std::borrow::Cow;
 use std::{fmt::Debug, marker::PhantomData, sync::Arc};
 
+use crate::{AbiDecode, AbiEncode};
+use ethers_core::abi::{Tokenizable, Tokenize};
+use ethers_core::types::Selector;
+use ethers_core::utils::id;
 use thiserror::Error as ThisError;
 
+/// A helper trait for types that represent all call input parameters of a specific function
+pub trait EthCall: Tokenizable + AbiDecode + Send + Sync {
+    /// The name of the function
+    fn function_name() -> Cow<'static, str>;
+
+    /// Retrieves the ABI signature for the call
+    fn abi_signature() -> Cow<'static, str>;
+
+    /// The selector of the function
+    fn selector() -> Selector {
+        id(Self::abi_signature())
+    }
+}
+
+impl<T: EthCall> AbiEncode for T {
+    fn encode(self) -> Result<Bytes, AbiError> {
+        let tokens = self.into_tokens();
+        let selector = Self::selector();
+        let encoded = ethers_core::abi::encode(&tokens);
+        let encoded: Vec<_> = selector
+            .iter()
+            .copied()
+            .chain(encoded.into_iter())
+            .collect();
+        Ok(encoded.into())
+    }
+}
+
 #[derive(ThisError, Debug)]
 /// An Error which is thrown when interacting with a smart contract
 pub enum ContractError<M: Middleware> {

ethers-contract/src/codec.rs

@@ -0,0 +1,14 @@
+use crate::AbiError;
+use ethers_core::types::Bytes;
+
+/// Trait for ABI encoding
+pub trait AbiEncode {
+    /// ABI encode the type
+    fn encode(self) -> Result<Bytes, AbiError>;
+}
+
+/// Trait for ABI decoding
+pub trait AbiDecode: Sized {
+    /// Decodes the ABI encoded data
+    fn decode(bytes: impl AsRef<[u8]>) -> Result<Self, AbiError>;
+}

ethers-contract/src/lib.rs

@@ -20,7 +20,7 @@ mod base;
 pub use base::{decode_function_data, encode_function_data, AbiError, BaseContract};
 
 mod call;
-pub use call::ContractError;
+pub use call::{ContractError, EthCall};
 
 mod factory;
 pub use factory::ContractFactory;
@@ -31,6 +31,9 @@ pub use event::EthEvent;
 mod log;
 pub use log::{decode_logs, EthLogDecode, LogMeta};
 
+mod codec;
+pub use codec::{AbiDecode, AbiEncode};
+
 mod stream;
 
 mod multicall;
@@ -50,7 +53,7 @@ pub use ethers_contract_abigen::Abigen;
 
 #[cfg(any(test, feature = "abigen"))]
 #[cfg_attr(docsrs, doc(cfg(feature = "abigen")))]
-pub use ethers_contract_derive::{abigen, EthAbiType, EthDisplay, EthEvent};
+pub use ethers_contract_derive::{abigen, EthAbiType, EthCall, EthDisplay, EthEvent};
 
 // Hide the Lazy re-export, it's just for convenience
 #[doc(hidden)]

ethers-contract/tests/abigen.rs

@@ -1,6 +1,6 @@
 #![cfg(feature = "abigen")]
 //! Test cases to validate the `abigen!` macro
-use ethers_contract::{abigen, EthEvent};
+use ethers_contract::{abigen, AbiDecode, AbiEncode, EthEvent};
 use ethers_core::abi::{Address, Tokenizable};
 use ethers_core::types::U256;
 use ethers_providers::Provider;
@@ -163,6 +163,8 @@ fn can_gen_human_readable_with_structs() {
         r#"[
         struct Foo { uint256 x; }
         function foo(Foo memory x)
+        function bar(uint256 x, uint256 y, address addr)
+        yeet(uint256,uint256,address)
     ]"#,
         event_derives(serde::Deserialize, serde::Serialize)
     );
@@ -172,6 +174,33 @@ fn can_gen_human_readable_with_structs() {
     let contract = SimpleContract::new(Address::default(), Arc::new(client));
     let f = Foo { x: 100u64.into() };
     let _ = contract.foo(f);
+
+    let call = BarCall {
+        x: 1u64.into(),
+        y: 0u64.into(),
+        addr: Address::random(),
+    };
+    let encoded_call = contract.encode("bar", (call.x, call.y, call.addr)).unwrap();
+    assert_eq!(encoded_call, call.clone().encode().unwrap());
+    let decoded_call = BarCall::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(call, decoded_call);
+
+    let contract_call = SimpleContractCalls::Bar(call);
+    let decoded_enum = SimpleContractCalls::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(contract_call, decoded_enum);
+    assert_eq!(encoded_call, contract_call.encode().unwrap());
+
+    let call = YeetCall(1u64.into(), 0u64.into(), Address::zero());
+    let encoded_call = contract.encode("yeet", (call.0, call.1, call.2)).unwrap();
+    assert_eq!(encoded_call, call.clone().encode().unwrap());
+    let decoded_call = YeetCall::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(call, decoded_call);
+
+    let contract_call = SimpleContractCalls::Yeet(call.clone());
+    let decoded_enum = SimpleContractCalls::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(contract_call, decoded_enum);
+    assert_eq!(contract_call, call.into());
+    assert_eq!(encoded_call, contract_call.encode().unwrap());
 }
 
 #[test]
@@ -192,4 +221,48 @@ fn can_handle_overloaded_functions() {
     let _ = contract.get_value();
     let _ = contract.get_value_with_other_value(1337u64.into());
     let _ = contract.get_value_with_other_value_and_addr(1337u64.into(), Address::zero());
+
+    let call = GetValueCall;
+
+    let encoded_call = contract.encode("getValue", ()).unwrap();
+    assert_eq!(encoded_call, call.clone().encode().unwrap());
+    let decoded_call = GetValueCall::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(call, decoded_call);
+
+    let contract_call = SimpleContractCalls::GetValue(call);
+    let decoded_enum = SimpleContractCalls::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(contract_call, decoded_enum);
+    assert_eq!(encoded_call, contract_call.encode().unwrap());
+
+    let call = GetValueWithOtherValueCall {
+        other_value: 420u64.into(),
+    };
+
+    let encoded_call = contract
+        .encode_with_selector([15, 244, 201, 22], call.other_value)
+        .unwrap();
+    assert_eq!(encoded_call, call.clone().encode().unwrap());
+    let decoded_call = GetValueWithOtherValueCall::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(call, decoded_call);
+
+    let contract_call = SimpleContractCalls::GetValueWithOtherValue(call);
+    let decoded_enum = SimpleContractCalls::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(contract_call, decoded_enum);
+    assert_eq!(encoded_call, contract_call.encode().unwrap());
+
+    let call = GetValueWithOtherValueAndAddrCall {
+        other_value: 420u64.into(),
+        addr: Address::random(),
+    };
+
+    let encoded_call = contract
+        .encode_with_selector([14, 97, 29, 56], (call.other_value, call.addr))
+        .unwrap();
+    let decoded_call = GetValueWithOtherValueAndAddrCall::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(call, decoded_call);
+
+    let contract_call = SimpleContractCalls::GetValueWithOtherValueAndAddr(call);
+    let decoded_enum = SimpleContractCalls::decode(encoded_call.as_ref()).unwrap();
+    assert_eq!(contract_call, decoded_enum);
+    assert_eq!(encoded_call, contract_call.encode().unwrap());
 }

ethers-contract/tests/common/derive.rs

@@ -1,9 +1,12 @@
 use ethers_contract::EthLogDecode;
-use ethers_contract::{abigen, EthAbiType, EthDisplay, EthEvent};
+use ethers_contract::{abigen, AbiDecode, EthAbiType, EthCall, EthDisplay, EthEvent};
 use ethers_core::abi::{RawLog, Tokenizable};
 use ethers_core::types::Address;
 use ethers_core::types::{H160, H256, I256, U128, U256};
 
+fn assert_tokenizeable<T: Tokenizable>() {}
+fn assert_ethcall<T: EthCall>() {}
+
 #[derive(Debug, Clone, PartialEq, EthAbiType)]
 struct ValueChanged {
     old_author: Address,
@@ -42,6 +45,22 @@ fn can_detokenize_struct() {
     assert_eq!(value, ValueChanged::from_token(token).unwrap());
 }
 
+#[test]
+fn can_derive_abi_type_empty_struct() {
+    #[derive(Debug, Clone, PartialEq, EthAbiType)]
+    struct Call();
+
+    #[derive(Debug, Clone, PartialEq, EthAbiType)]
+    struct Call2 {};
+
+    #[derive(Debug, Clone, PartialEq, EthAbiType)]
+    struct Call3;
+
+    assert_tokenizeable::<Call>();
+    assert_tokenizeable::<Call2>();
+    assert_tokenizeable::<Call3>();
+}
+
 #[test]
 fn can_detokenize_nested_structs() {
     let value = ValueChangedWrapper {
@@ -319,6 +338,27 @@ fn can_decode_event_single_param() {
     assert_eq!(event.param1, 123u64.into());
 }
 
+#[test]
+fn can_decode_event_tuple_single_param() {
+    #[derive(Debug, PartialEq, EthEvent)]
+    struct OneParam(#[ethevent(indexed)] U256);
+
+    let log = RawLog {
+        topics: vec![
+            "bd9bb67345a2fcc8ef3b0857e7e2901f5a0dcfc7fe5e3c10dc984f02842fb7ba"
+                .parse()
+                .unwrap(),
+            "000000000000000000000000000000000000000000000000000000000000007b"
+                .parse()
+                .unwrap(),
+        ],
+        data: vec![],
+    };
+
+    let event = <OneParam as EthLogDecode>::decode_log(&log).unwrap();
+    assert_eq!(event.0, 123u64.into());
+}
+
 #[test]
 fn can_decode_event_with_no_params() {
     #[derive(Debug, PartialEq, EthEvent)]
@@ -389,3 +429,61 @@ fn eth_display_works_for_human_readable() {
     };
     assert_eq!("abc".to_string(), format!("{}", log));
 }
+
+#[test]
+fn can_derive_ethcall() {
+    #[derive(Debug, Clone, EthCall, EthDisplay)]
+    struct MyStruct {
+        addr: Address,
+        old_value: String,
+        new_value: String,
+        h: H256,
+        i: I256,
+        arr_u8: [u8; 32],
+        arr_u16: [u16; 32],
+        v: Vec<u8>,
+    }
+
+    assert_tokenizeable::<MyStruct>();
+    assert_ethcall::<MyStruct>();
+
+    #[derive(Debug, Clone, EthCall, EthDisplay)]
+    #[ethcall(name = "my_call")]
+    struct MyCall {
+        addr: Address,
+        old_value: String,
+        new_value: String,
+    }
+    assert_eq!(
+        MyCall::abi_signature().as_ref(),
+        "my_call(address,string,string)"
+    );
+
+    assert_tokenizeable::<MyCall>();
+    assert_ethcall::<MyCall>();
+}
+
+#[test]
+fn can_derive_ethcall_with_nested_structs() {
+    #[derive(Debug, Clone, PartialEq, EthAbiType)]
+    struct SomeType {
+        inner: Address,
+        msg: String,
+    }
+
+    #[derive(Debug, PartialEq, EthCall)]
+    #[ethcall(name = "foo", abi = "foo(address,(address,string),string)")]
+    struct FooCall {
+        old_author: Address,
+        inner: SomeType,
+        new_value: String,
+    }
+
+    assert_eq!(
+        FooCall::abi_signature().as_ref(),
+        "foo(address,(address,string),string)"
+    );
+
+    assert_tokenizeable::<FooCall>();
+    assert_ethcall::<FooCall>();
+}

ethers-core/src/abi/human_readable.rs

@@ -337,14 +337,16 @@ impl AbiParser {
 
         let state_mutability = modifiers.map(detect_state_mutability).unwrap_or_default();
 
+        Ok(
             #[allow(deprecated)]
-        Ok(Function {
+            Function {
                 name,
                 inputs,
                 outputs,
                 state_mutability,
                 constant: false,
-        })
+            },
+        )
     }
 
     fn parse_params(&self, s: &str) -> Result<Vec<(Param, Option<String>)>> {

ethers-core/src/types/i256.rs

@@ -59,9 +59,7 @@ fn twos_complement(u: U256) -> U256 {
 fn handle_overflow<T>((result, overflow): (T, bool)) -> T {
     #[cfg(debug_assertions)]
     {
-        if overflow {
+        assert!(!overflow, "overflow");
-            panic!("overflow");
-        }
     }
 
     let _ = overflow;

ethers-core/src/types/transaction/eip712.rs

@@ -483,7 +483,7 @@ pub fn find_parameter_type(ty: &Type) -> Result<ParamType, TokenStream> {
             let params = ty
                 .elems
                 .iter()
-                .map(|t| find_parameter_type(t))
+                .map(find_parameter_type)
                 .collect::<Result<Vec<_>, _>>()?;
             Ok(ParamType::Tuple(params))
         }