## Proposed Changes
Update test vectors for v0.12.3, and introduced configurable `proportional_slashing_multiplier`.
Also makes `YamlConfig` a bit safer by making every field access in `apply_to_chain_spec` explicit, and removing the `#[serde(default)]` attribute, which would instantiate missing fields to type defaults! Risky!
## Issue Addressed
Resolves#1100
## Proposed Changes
* Implement the `SafeArith` trait for `Slot` and `Epoch`, so that methods like `safe_add` become available.
* Tweak the `SafeArith` trait to allow a different `Rhs` type (analagous to `std::ops::Add`, etc).
* Add a `legacy-arith` feature to `types` and `state_processing` that conditionally enables implementations of
the `std` ops with saturating semantics.
* Check compilation of `types` and `state_processing` _without_ `legacy-arith` on CI,
thus guaranteeing that they only use the `SafeArith` primitives 🎉
## Additional Info
The `legacy-arith` feature gets turned on by all higher-level crates that depend on `state_processing` or `types`, thus allowing the beacon chain, networking, and other components to continue to rely on the availability of ops like `+`, `-`, `*`, etc.
**This is a consensus-breaking change**, but brings us in line with the spec, and our incompatibilities shouldn't have been reachable with any valid configuration of Eth2 parameters.
## Issue Addressed
- Resolves#1080
## Proposed Changes
- Call `update_pubkey_cache` only in the `build_all_caches` method and `get_validator_index` method.
## Additional Info
This does reduce the number of places the cache is updated, making it simpler. But the `get_validator_index` method is used a couple times when we are iterating through the entire validator registry (or set of active validators). Before, we would only call `update_pubkey_cache` once before iterating through all validators. So I'm not _totally_ sure this change is worth it.
## Issue Addressed
Closes#1098
## Proposed Changes
Add a `SafeArithIter` trait with a `safe_sum` method, and use it in `state_processing`. This seems to be the only place in `consensus` where it is relevant -- i.e. where we were using `sum` and the integer_arith lint is enabled.
## Additional Info
This PR doesn't include any Clippy linting to prevent `sum` from being called. It seems there is no existing Clippy lint that suits our purpose, but I'm going to look into that and maybe schedule writing one as a lower-priority task.
This theoretically _is_ a consensus breaking change, but it shouldn't impact Medalla (or any other testnet) because `slashings` shouldn't overflow!
## Issue Addressed
Closes#1076
## Proposed Changes
Remove an extra unnecessary decompression of the deposit public key from `process_deposit`. The key is decompressed and used to verify the signature in `verify_deposit_signature`, making this initial decompression redundant.
## Additional Info
This is _not_ a consensus-breaking change because keys which previously failed the early decompression check will not be found in the pubkey cache (they are invalid), and will be checked and rejected as part of `verify_deposit_signature`.
## Issue Addressed
NA
## Proposed Changes
- Refactor the `bls` crate to support multiple BLS "backends" (e.g., milagro, blst, etc).
- Removes some duplicate, unused code in `common/rest_types/src/validator.rs`.
- Removes the old "upgrade legacy keypairs" functionality (these were unencrypted keys that haven't been supported for a few testnets, no one should be using them anymore).
## Additional Info
Most of the files changed are just inconsequential changes to function names.
## TODO
- [x] Optimization levels
- [x] Infinity point: https://github.com/supranational/blst/issues/11
- [x] Ensure milagro *and* blst are tested via CI
- [x] What to do with unsafe code?
- [x] Test infinity point in signature sets
* Process exits and slashings off the network
* Fix rest_api tests
* Add op verification tests
* Add tests for pruning of slashings in the op pool
* Address Paul's review comments
* Update state processing for v0.12
* Fix EF test runners for v0.12
* Fix some tests
* Fix broken attestation verification test
* More test fixes
* Fix typo found in review
