Fixes a parsing issue of EIP712 chain_id (chain_id = 80001 parsed as chain_id = 0x80001)

[alexisrobert]

Motivation

When using the Eip712 derive macro for a contract on the Polygon chain, chain_ids seem to be not parsed correctly.

use ethers::contract::EthAbiType;
use ethers_derive_eip712::*;
use ethers::core::types::U256;
use ethers::core::types::transaction::eip712::Eip712;

#[derive(Debug, Clone, Eip712, EthAbiType)]
#[eip712(
    name = "TestContract",
    version = "0.1",
    chain_id = 80001,
    verifying_contract = "0x0000000000000000000000000000000000000001"
)]
pub struct TestRequest {
    pub nonce: U256,
}

fn main() {
    let msg = TestRequest {
        nonce: U256::from(1_u32),
    };

    println!("{:#?}", msg.domain().unwrap());
}

This outputs the following domain, with a chain_id that seems incorrect (and not validated by the Solidity contract) :

EIP712Domain {
    name: "TestContract",
    version: "0.1",
    chain_id: 524289,
    verifying_contract: 0x0000000000000000000000000000000000000001,
    salt: None,
}

The chain_id of 524289 is equal to 0x80001 where it should normally be 80001 in decimal.

Solution

I changed the parsing of domain.chain_id to be parsed into a u64, instead of directly to the U256 type.

After being parsed to u64, I convert it to U256.