fix: support eip712 domain chain ids as string (#1756)

* fix: support eip712 domain chain ids as string

* chore: add rustfmt.toml

ethers-core/src/types/serde_helpers.rs

@@ -254,3 +254,25 @@ where
     let num = <[LenientBlockNumber; 1]>::deserialize(deserializer)?[0].into();
     Ok(num)
 }
+
+#[cfg(test)]
+mod tests {
+
+    #[test]
+    #[cfg(feature = "eip712")]
+    fn test_deserialize_string_chain_id() {
+        use crate::types::transaction::eip712::EIP712Domain;
+
+        let val = serde_json::json!(
+                  {
+          "name": "Seaport",
+          "version": "1.1",
+          "chainId": "137",
+          "verifyingContract": "0x00000000006c3852cbEf3e08E8dF289169EdE581"
+        }
+              );
+
+        let domain: EIP712Domain = serde_json::from_value(val).unwrap();
+        assert_eq!(domain.chain_id, Some(137u64.into()));
+    }
+}

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

@@ -131,7 +131,7 @@ pub struct EIP712Domain {
     #[serde(
         default,
         skip_serializing_if = "Option::is_none",
-        deserialize_with = "crate::types::serde_helpers::deserialize_number_opt"
+        deserialize_with = "crate::types::serde_helpers::deserialize_stringified_numeric_opt"
     )]
     pub chain_id: Option<U256>,