chore: stale FIXME in evm-node says the Arc chain spec is not defined yet (it is, and is used throughout)

[mehmetkr-31]

Summary

crates/evm-node/src/node.rs carries a FIXME saying the Arc chain spec still needs to be defined:

// FIXME use the ethereum chain spec temporary, we need to define Arc chain spec
// original traits for ChainSpec in this file `Hardforks + EthereumHardforks + EthExecutorSpec`

The Arc chain spec already exists, and this file already uses it — confirmed two ways:

1. ArcChainSpec is defined in crates/execution-config/src/chainspec.rs, and node.rs imports it and binds ChainSpec = ArcChainSpec throughout (type ChainSpec = ArcChainSpec;, and in every NodeTypes<ChainSpec = ArcChainSpec, ...> bound).
2. It was already true in the first public commit, a1235c0 (2026-04-06): node.rs used ArcChainSpec 10 times there and the struct was already defined. So the FIXME has been stale since the day it landed.

Why this is worth fixing

A FIXME saying "we need to define Arc chain spec" in a file that is built entirely around ArcChainSpec points the next reader at work that was finished before the repo went public. Two-line removal.

Note

The second line records the ChainSpec trait bounds of the upstream reth file node.rs was forked from. It only reads sensibly as a continuation of the FIXME, so I would remove both — but it is a porting hint, and if keeping it as a standalone note is preferred that is an easy change.

[osr21]

Confirmed. This is a valid stale-comment cleanup, not a missing implementation.

On current main, crates/evm-node/src/node.rs imports arc_execution_config::chainspec::ArcChainSpec, defines impl NodeTypes for ArcNode { type ChainSpec = ArcChainSpec; }, and repeats NodeTypes<ChainSpec = ArcChainSpec, ...> in the relevant bounds. ArcChainSpec is defined in crates/execution-config/src/chainspec.rs with its Arc-specific chain configuration and hardfork behavior.

The historical check is especially useful: the same import, type ChainSpec = ArcChainSpec, and FIXME are already present at commit a1235c0. So the comment has been stale since the first public version; this is not evidence of a recent regression or unfinished chain-spec migration.

I also found no current EthereumChainSpec, EthereumHardforks, or EthExecutorSpec reference in this node implementation that would make the FIXME actionable. Removing both lines is therefore behavior-neutral and removes a misleading porting note. If maintainers want to preserve the trait context, it should be rewritten as an accurate standalone note about the traits ArcChainSpec satisfies, not left in the form "we need to define Arc chain spec."

This should not require a special test beyond the repository's normal formatting/check workflow: the proposed change only deletes comments and does not alter the chain-spec type, bounds, or runtime behavior.

Disclosure: I'm an external community contributor, not affiliated with Circle, with no write access to this repository. Advisory review only, not an approval.