lighthouse/Cargo.toml
Paul Hauner fe52322088 Implement SSZ union type (#2579)
## Issue Addressed

NA

## Proposed Changes

Implements the "union" type from the SSZ spec for `ssz`, `ssz_derive`, `tree_hash` and `tree_hash_derive` so it may be derived for `enums`:

https://github.com/ethereum/consensus-specs/blob/v1.1.0-beta.3/ssz/simple-serialize.md#union

The union type is required for the merge, since the `Transaction` type is defined as a single-variant union `Union[OpaqueTransaction]`.

### Crate Updates

This PR will (hopefully) cause CI to publish new versions for the following crates:

- `eth2_ssz_derive`: `0.2.1` -> `0.3.0`
- `eth2_ssz`: `0.3.0` -> `0.4.0`
- `eth2_ssz_types`: `0.2.0` -> `0.2.1`
- `tree_hash`: `0.3.0` -> `0.4.0`
- `tree_hash_derive`: `0.3.0` -> `0.4.0`

These these crates depend on each other, I've had to add a workspace-level `[patch]` for these crates. A follow-up PR will need to remove this patch, ones the new versions are published.

### Union Behaviors

We already had SSZ `Encode` and `TreeHash` derive for enums, however it just did a "transparent" pass-through of the inner value. Since the "union" decoding from the spec is in conflict with the transparent method, I've required that all `enum` have exactly one of the following enum-level attributes:

#### SSZ

-  `#[ssz(enum_behaviour = "union")]`
    - matches the spec used for the merge
-  `#[ssz(enum_behaviour = "transparent")]`
    - maintains existing functionality
    - not supported for `Decode` (never was)
    
#### TreeHash

-  `#[tree_hash(enum_behaviour = "union")]`
    - matches the spec used for the merge
-  `#[tree_hash(enum_behaviour = "transparent")]`
    - maintains existing functionality

This means that we can maintain the existing transparent behaviour, but all existing users will get a compile-time error until they explicitly opt-in to being transparent.

### Legacy Option Encoding

Before this PR, we already had a union-esque encoding for `Option<T>`. However, this was with the *old* SSZ spec where the union selector was 4 bytes. During merge specification, the spec was changed to use 1 byte for the selector.

Whilst the 4-byte `Option` encoding was never used in the spec, we used it in our database. Writing a migrate script for all occurrences of `Option` in the database would be painful, especially since it's used in the `CommitteeCache`. To avoid the migrate script, I added a serde-esque `#[ssz(with = "module")]` field-level attribute to `ssz_derive` so that we can opt into the 4-byte encoding on a field-by-field basis.

The `ssz::legacy::four_byte_impl!` macro allows a one-liner to define the module required for the `#[ssz(with = "module")]` for some `Option<T> where T: Encode + Decode`.

Notably, **I have removed `Encode` and `Decode` impls for `Option`**. I've done this to force a break on downstream users. Like I mentioned, `Option` isn't used in the spec so I don't think it'll be *that* annoying. I think it's nicer than quietly having two different union implementations or quietly breaking the existing `Option` impl.

### Crate Publish Ordering

I've modified the order in which CI publishes crates to ensure that we don't publish a crate without ensuring we already published a crate that it depends upon.

## TODO

- [ ] Queue a follow-up `[patch]`-removing PR.
2021-09-25 05:58:36 +00:00

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2.2 KiB
TOML

[workspace]
members = [
"account_manager",
"beacon_node",
"beacon_node/beacon_chain",
"beacon_node/client",
"beacon_node/eth1",
"beacon_node/eth2_libp2p",
"beacon_node/http_api",
"beacon_node/http_metrics",
"beacon_node/network",
"beacon_node/store",
"beacon_node/timer",
"boot_node",
"common/account_utils",
"common/clap_utils",
"common/compare_fields",
"common/compare_fields_derive",
"common/deposit_contract",
"common/directory",
"common/eth2",
"common/eth2_config",
"common/eth2_interop_keypairs",
"common/eth2_network_config",
"common/eth2_wallet_manager",
"common/hashset_delay",
"common/lighthouse_metrics",
"common/lighthouse_version",
"common/lockfile",
"common/logging",
"common/lru_cache",
"common/malloc_utils",
"common/sensitive_url",
"common/slot_clock",
"common/task_executor",
"common/target_check",
"common/test_random_derive",
"common/validator_dir",
"common/warp_utils",
"common/fallback",
"common/monitoring_api",
"consensus/cached_tree_hash",
"consensus/int_to_bytes",
"consensus/fork_choice",
"consensus/proto_array",
"consensus/safe_arith",
"consensus/ssz",
"consensus/ssz_derive",
"consensus/ssz_types",
"consensus/serde_utils",
"consensus/state_processing",
"consensus/swap_or_not_shuffle",
"consensus/tree_hash",
"consensus/tree_hash_derive",
"crypto/bls",
"crypto/eth2_hashing",
"crypto/eth2_key_derivation",
"crypto/eth2_keystore",
"crypto/eth2_wallet",
"lcli",
"lighthouse",
"lighthouse/environment",
"slasher",
"slasher/service",
"testing/ef_tests",
"testing/eth1_test_rig",
"testing/node_test_rig",
"testing/simulator",
"testing/state_transition_vectors",
"testing/web3signer_tests",
"validator_client",
"validator_client/slashing_protection",
]
[patch]
[patch.crates-io]
eth2_ssz = { path = "consensus/ssz" }
eth2_ssz_types = { path = "consensus/ssz_types" }
eth2_ssz_derive = { path = "consensus/ssz_derive" }
tree_hash = { path = "consensus/tree_hash" }
tree_hash_derive = { path = "consensus/tree_hash_derive" }