[flyq]

Summary

Move the pinned compiler from nightly-2026-02-03 to nightly-2026-04-23, the first nightly with the fix for a closure-call code-generation bug (rust-lang/rust#155241, fixed by rust-lang/rust#155343).
mega-evm moved to the same nightly in megaeth-labs/mega-evm#411, and mega-reth follows in megaeth-labs/mega-reth#2561.

Why

With an affected compiler, a by-value argument larger than two words (a Vec, say) passed to a closure call can be the caller's own memory instead of a temporary copy, so the callee mutates it in place.
In optimized builds this shows as silently wrong values on 1.77–1.90 and as a double free from 1.91 on.
nightly-2026-02-03 is 1.95.0-nightly, inside that range, and every release binary is built with it, mega-evm included.
mega-evm#411 notes that a downstream build on an affected compiler needs its own pin update.

No impact has been observed: mega-evm replayed mainnet blocks under both compilers with byte-identical results, and mega-reth#2561 did the same through the stateless-core validation path.
A miscompile cannot be ruled out code path by code path, so the fix is the compiler.

Changes

• rust-toolchain.toml: nightly-2026-02-03 → nightly-2026-04-23 (1.97.0-nightly, LLVM 22.1.2).
• AGENTS.md (and so CLAUDE.md, a symlink to it): the documented toolchain.

No source changes: the new nightly brings no rustfmt or Clippy findings in either CI configuration.

Compatibility

• rust-version stays 1.94.
  mega-reth builds stateless-common, stateless-core and stateless-r2 with its own pinned compiler, and raising it would make mega-reth's 1.94.0-nightly refuse them.
• Those three crates still compile on mega-reth develop's nightly-2025-12-20 (cargo +nightly-2025-12-20 check --ignore-rust-version, with default features, --all-features and --no-default-features), so this lands independently of mega-reth#2561.
• coverage-replayer folds rustc -vV (release, commit hash, LLVM version) into its binary_id, so stores scanned with the old compiler do not carry over; carry the candidate pool across with inspect --dump-pool before the next scan.

Tests

On nightly-2026-04-23:

• cargo test --workspace: 622 passed, 0 failed, 40 ignored (the endpoint-backed debug-trace-server integration tests), the same as on the old compiler; the test profile is optimized, where the bug shows.
  This includes validate_block_mainnet_fixtures over all 63 mainnet fixture blocks and replays_mainnet_fixtures_with_header_sanity.
• cargo fmt --all --check, cargo sort --check, and both CI Clippy configurations: clean.

🤖 Generated with Claude Code

[mega-maxwell]

Claude review status

Living comment — rewritten in place. The review workflow keeps this single comment up to date instead of posting a new one each round, so it always describes the latest reviewed commit and the earlier text is intentionally gone. No reply is needed here; reply to a finding in its own review thread, and answer an open question in a reply on this PR. The next review round reconciles your answer.

🛠️ Review did not finish

Attempted head 99c6ed29 · updated 2026-11-03T09:17:46+00:00

This round did not publish: MODEL_ACTION_FAILED: The Claude review retry action failed.. Anything listed below is from the last round that did. Workflow run: https://github.com/megaeth-labs/stateless-validator/actions/runs/41609772022