[Feature] custom deserde impl for executionpayload

[siosw]

Component

rpc

Describe the feature you would like

as described in #2004

alloy/crates/rpc-types-engine/src/payload.rs

Lines 827 to 832 in 0fbc37d

	/// An execution payload, which can be either [ExecutionPayloadV1], [ExecutionPayloadV2], or
	/// [ExecutionPayloadV3].
	#[derive(Clone, Debug, PartialEq, Eq)]
	#[cfg_attr(feature = "serde", derive(serde::Serialize))]
	#[cfg_attr(feature = "serde", serde(untagged))]
	pub enum ExecutionPayload {

right now if we have a ExecutionPayloadV3 json, we can still do:
let payload: ExecutionPayloadV2 = serde_json::from_str(json).unwrap();

and extra fields just implicitly get ignored. but obv you can no longer roundtrip then.

Originally posted by @siosw in #2004

a custom deserde impl could enforce that executionpayload can only be deserialized into the correct version

Additional context

@mattsse i think i have a PR that fixes this but it adds a lot of boilerplate, maybe there is a better way to do it

[siosw]

closed by #2017