## Proposed Changes
Set a minimum supported Rust version (MSRV) in the `Cargo.toml` for the Lighthouse binary so that attempts to compile it with an outdated compiler fail immediately with a clear error.
To ensure that the codebase builds with the MSRV I've also added a Github actions job that runs `cargo check` using the MSRV extracted from `Cargo.toml`. This will force us to keep it up to date.
I opted to use `cargo check` rather than Clippy because Clippy frequently introduces new lints that we adopt, so our MSRV for Clippy is usually the most recent Rust version, while the MSRV for building Lighthouse is older.
## Issue Addressed
As discussed on last-night's consensus call, the testnets next week will target the [Kiln Spec v2](https://hackmd.io/@n0ble/kiln-spec).
Presently, we support Kiln V1. V2 is backwards compatible, except for renaming `random` to `prev_randao` in:
- https://github.com/ethereum/execution-apis/pull/180
- https://github.com/ethereum/consensus-specs/pull/2835
With this PR we'll no longer be compatible with the existing Kintsugi and Kiln testnets, however we'll be ready for the testnets next week. I raised this breaking change in the call last night, we are all keen to move forward and break things.
We now target the [`merge-kiln-v2`](https://github.com/MariusVanDerWijden/go-ethereum/tree/merge-kiln-v2) branch for interop with Geth. This required adding the `--http.aauthport` to the tester to avoid a port conflict at startup.
### Changes to exec integration tests
There's some change in the `merge-kiln-v2` version of Geth that means it can't compile on a vanilla Github runner. Bumping the `go` version on the runner solved this issue.
Whilst addressing this, I refactored the `testing/execution_integration` crate to be a *binary* rather than a *library* with tests. This means that we don't need to run the `build.rs` and build Geth whenever someone runs `make lint` or `make test-release`. This is nice for everyday users, but it's also nice for CI so that we can have a specific runner for these tests and we don't need to ensure *all* runners support everything required to build all execution clients.
## More Info
- [x] ~~EF tests are failing since the rename has broken some tests that reference the old field name. I have been told there will be new tests released in the coming days (25/02/22 or 26/02/22).~~
## Issue Addressed
Timeouts due to Windows builds running for 2h 20m.
## Proposed Changes
* Increase Bors timeout to 3h
* Refine the target branch check so that it will pass when we make PRs to feature branches. This is just an extra change I've been meaning to sneak in for a while.
## Additional Info
* I think it would also be cool to try caching for CI again, but that's a separate issue and we'll still need the long timeout on a cache miss.
Attempt to prevent accidental merges to `stable` due to GitHub's default behaviour of opening PRs against it.
I've intentionally opened this PR against `stable` to test the functionality ;)
## Issue Addressed
N/A
## Proposed Changes
Remove the MacOs tests. They routinely fail, causing bors to retry and slowing down the whole merge process.
## Additional Info
N/A
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
