Event listeners with filtering, what is the expected behavior?

[markszente]

Hello,

I have discovered an interesting behavior in event listeners. To put it short, event parameters are not destructed when you apply filtering. For reference, the docs say

When adding event listeners for a named event, the event parameters are destructed for the listener.

So, from the examples, this would work as expected:

contract.on("Transfer", (from, to, _amount, event) => {
  const amount = formatEther(_amount, 18)
  console.log(`${ from } => ${ to }: ${ amount }`);

  // The `event.log` has the entire EventLog

  // Optionally, stop listening
  event.removeListener();
});

This, however, would not:

// Listen for any Transfer to "ethers.eth"
filter = contract.filters.Transfer("ethers.eth")
contract.on(filter, (from, to, amount, event) => {
  // `to` will always be equal to the address of "ethers.eth"
});

In the second example, from is actually the event object itself, with the rest of the arguments being undefined.

Tested it with 6.13.4, both on a local Hardhat network, and Ethereum mainnet with Alchemy.