Refactor revm_spec function to simplify hardfork detection logic

[cypherpepe]

Replaced individual hardfork checks in revm_spec with a loop-based approach using find. Moved hardfork-to-SpecId mapping logic to a separate helper function (map_hardfork_to_spec_id) for cleaner and more maintainable code.

[onbjerg]

please use forks_iter()

[onbjerg]

some of these are OptimismHardfork, which means we'd need dynamic dispatch. not really sure this is the way to go

[cypherpepe]

Given the issue with handling both EthereumHardfork and OptimismHardfork, would you recommend simplifying revm_spec by removing map_hardfork_to_spec_id altogether and directly matching on each fork type? Here’s what that would look like:

fn revm_spec(chain_spec: &ChainSpec, block: &Head) -> SpecId {
    chain_spec
        .forks_iter()
        .find(|(_, condition)| condition.active_at_head(block))
        .map_or_else(
            || {
                panic!(
                    "Invalid chainspec: expected at least one active hardfork, got {:?}",
                    chain_spec.hardforks
                );
            },
            |(fork, _)| {
                if let Some(eth_fork) = fork.downcast_ref::<EthereumHardfork>() {
                    match eth_fork {
                        EthereumHardfork::Prague => SpecId::OSAKA,
                        // (other EthereumHardfork mappings)
                    }
                } else if let Some(opt_fork) = fork.downcast_ref::<OptimismHardfork>() {
                    match opt_fork {
                        OptimismHardfork::Granite => SpecId::GRANITE,
                        // (other OptimismHardfork mappings)
                    }
                } else {
                    panic!("Unsupported hardfork: {:?}", fork);
                }
            }
        )
}

This approach would avoid dynamic dispatch and handle both fork types without additional casting. Do you think this is a better solution?

[onbjerg]

I guess, although I think it would be more readable with 2 mapping functions. I question if this is indeed more readable at that point though

[mattsse]

I find the if else chain easier to read/maintain

[cypherpepe]

Thank you for the feedback. I'll keep your suggestions in mind and continue looking for ways to support the team. Let's close this thread, as these changes are not the right fit.

[mattsse]

appreciate it