feat: substitute overloaded functions (#501)

* feat: substitute overloaded functions

* chore: update changelog

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Unreleased
 
+- `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)
 - Use rust types as contract function inputs for human readable abi [#482](https://github.com/gakonst/ethers-rs/pull/482)
 - Add EIP-712 `sign_typed_data` signer method; add ethers-core type `Eip712` trait and derive macro in ethers-derive-eip712 [#481](https://github.com/gakonst/ethers-rs/pull/481)

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

@@ -1,21 +1,25 @@
-use super::{types, util, Context};
+use std::collections::BTreeMap;
+
 use anyhow::{Context as _, Result};
+use inflector::Inflector;
+use proc_macro2::{Literal, TokenStream};
+use quote::quote;
+use syn::Ident;
+
 use ethers_core::abi::ParamType;
 use ethers_core::{
     abi::{Function, FunctionExt, Param},
     types::Selector,
 };
-use inflector::Inflector;
-use proc_macro2::{Literal, TokenStream};
-use quote::quote;
-use std::collections::BTreeMap;
-use syn::Ident;
+
+use super::{types, util, Context};
 
 /// Expands a context into a method struct containing all the generated bindings
 /// to the Solidity contract methods.
 impl Context {
+    /// Expands all method implementations
     pub(crate) fn methods(&self) -> Result<TokenStream> {
-        let mut aliases = self.method_aliases.clone();
+        let mut aliases = self.get_method_aliases()?;
         let sorted_functions: BTreeMap<_, _> = self.abi.functions.clone().into_iter().collect();
         let functions = sorted_functions
             .values()
@@ -43,8 +47,10 @@ impl Context {
             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,))`
-                // this is currently necessary because internally `flatten_tokens` is called which removes the outermost `tuple` level
-                // and since `((#name))` is not a rust tuple it doesn't get wrapped into another tuple that will be peeled off by `flatten_tokens`
+                // this is currently necessary because internally `flatten_tokens` is called which
+                // removes the outermost `tuple` level and since `((#name))` is not
+                // a rust tuple it doesn't get wrapped into another tuple that will be peeled off by
+                // `flatten_tokens`
                 ParamType::Tuple(_) if fun.inputs.len() == 1 => {
                     // make sure the tuple gets converted to `Token::Tuple`
                     quote! {(#name,)}
@@ -97,16 +103,16 @@ impl Context {
         }
     }
 
-    #[allow(unused)]
+    /// Expands a single function with the given alias
     fn expand_function(&self, function: &Function, alias: Option<Ident>) -> Result<TokenStream> {
         let name = alias.unwrap_or_else(|| util::safe_ident(&function.name.to_snake_case()));
         let selector = expand_selector(function.selector());
 
         // 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_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> };
@@ -127,6 +133,79 @@ impl Context {
             }
         })
     }
+
+    /// Returns the method aliases, either configured by the user or determined
+    /// based on overloaded functions.
+    ///
+    /// In case of overloaded functions we would follow rust's general
+    /// convention of suffixing the function name with _with
+    // The first function or the function with the least amount of arguments should
+    // be named as in the ABI, the following functions suffixed with _with_ +
+    // additional_params[0].name + (_and_(additional_params[1+i].name))*
+    fn get_method_aliases(&self) -> Result<BTreeMap<String, Ident>> {
+        let mut aliases = self.method_aliases.clone();
+        // find all duplicates, where no aliases where provided
+        for functions in self.abi.functions.values() {
+            if functions
+                .iter()
+                .filter(|f| !aliases.contains_key(&f.abi_signature()))
+                .count()
+                <= 1
+            {
+                // no conflicts
+                continue;
+            }
+
+            // sort functions by number of inputs asc
+            let mut functions = functions.iter().collect::<Vec<_>>();
+            functions.sort_by(|f1, f2| f1.inputs.len().cmp(&f2.inputs.len()));
+            let prev = functions[0];
+            for duplicate in functions.into_iter().skip(1) {
+                // attempt to find diff in the input arguments
+                let diff = duplicate
+                    .inputs
+                    .iter()
+                    .filter(|i1| prev.inputs.iter().all(|i2| *i1 != i2))
+                    .collect::<Vec<_>>();
+
+                let alias = match diff.len() {
+                    0 => {
+                        // this should not happen since functions with same name and input are
+                        // illegal
+                        anyhow::bail!(
+                            "Function with same name and parameter types defined twice: {}",
+                            duplicate.name
+                        );
+                    }
+                    1 => {
+                        // single additional input params
+                        format!(
+                            "{}_with_{}",
+                            duplicate.name.to_snake_case(),
+                            diff[0].name.to_snake_case()
+                        )
+                    }
+                    _ => {
+                        // 1 + n additional input params
+                        let and = diff
+                            .iter()
+                            .skip(1)
+                            .map(|i| i.name.to_snake_case())
+                            .collect::<Vec<_>>()
+                            .join("_and_");
+                        format!(
+                            "{}_with_{}_and_{}",
+                            duplicate.name.to_snake_case(),
+                            diff[0].name.to_snake_case(),
+                            and
+                        )
+                    }
+                };
+                aliases.insert(duplicate.abi_signature(), util::safe_ident(&alias));
+            }
+        }
+        Ok(aliases)
+    }
 }
 
 fn expand_fn_outputs(outputs: &[Param]) -> Result<TokenStream> {
@@ -150,9 +229,10 @@ fn expand_selector(selector: Selector) -> TokenStream {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use ethers_core::abi::ParamType;
 
+    use super::*;
+
     // packs the argument in a tuple to be used for the contract call
     fn expand_inputs_call_arg(inputs: &[Param]) -> TokenStream {
         let names = inputs
@@ -162,9 +242,12 @@ mod tests {
                 let name = util::expand_input_name(i, &param.name);
                 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,))`
-                    // this is currently necessary because internally `flatten_tokens` is called which removes the outermost `tuple` level
-                    // and since `((#name))` is not a rust tuple it doesn't get wrapped into another tuple that will be peeled off by `flatten_tokens`
+                    // we need to force this argument into a tuple so it gets expanded to
+                    // `((#name,))` this is currently necessary because
+                    // internally `flatten_tokens` is called which removes the outermost `tuple`
+                    // level and since `((#name))` is not a rust tuple it
+                    // doesn't get wrapped into another tuple that will be peeled off by
+                    // `flatten_tokens`
                     ParamType::Tuple(_) if inputs.len() == 1 => {
                         // make sure the tuple gets converted to `Token::Tuple`
                         quote! {(#name,)}

ethers-contract/tests/abigen.rs

@@ -173,3 +173,23 @@ fn can_gen_human_readable_with_structs() {
     let f = Foo { x: 100u64.into() };
     let _ = contract.foo(f);
 }
+
+#[test]
+fn can_handle_overloaded_functions() {
+    abigen!(
+        SimpleContract,
+        r#"[
+        getValue() (uint256)
+        getValue(uint256 otherValue) (uint256)
+        getValue(uint256 otherValue, address addr) (uint256)
+    ]"#
+    );
+
+    let (provider, _) = Provider::mocked();
+    let client = Arc::new(provider);
+    let contract = SimpleContract::new(Address::zero(), client);
+    // ensure both functions are callable
+    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());
+}