Fix previous_epoch_participation and current_epoch_participation initialization

specs/lightclient/beacon-chain.md

@@ -34,6 +34,7 @@
       - [`get_inactivity_penalty_deltas`](#get_inactivity_penalty_deltas)
   - [Block processing](#block-processing)
     - [New `process_attestation`](#new-process_attestation)
+    - [New `process_deposit`](#new-process_deposit)
     - [Sync committee processing](#sync-committee-processing)
   - [Epoch processing](#epoch-processing)
     - [New `process_justification_and_finalization`](#new-process_justification_and_finalization)
@@ -368,6 +369,51 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
     assert is_valid_indexed_attestation(state, get_indexed_attestation(state, attestation))
 ```
 
+
+#### New `process_deposit`
+
+*Note*: The function `process_deposit` is modified to initialize `previous_epoch_participation` and `current_epoch_participation`.
+
+```python
+def process_deposit(state: BeaconState, deposit: Deposit) -> None:
+    # Verify the Merkle branch
+    assert is_valid_merkle_branch(
+        leaf=hash_tree_root(deposit.data),
+        branch=deposit.proof,
+        depth=DEPOSIT_CONTRACT_TREE_DEPTH + 1,  # Add 1 for the List length mix-in
+        index=state.eth1_deposit_index,
+        root=state.eth1_data.deposit_root,
+    )
+
+    # Deposits must be processed in order
+    state.eth1_deposit_index += 1
+
+    pubkey = deposit.data.pubkey
+    amount = deposit.data.amount
+    validator_pubkeys = [v.pubkey for v in state.validators]
+    if pubkey not in validator_pubkeys:
+        # Verify the deposit signature (proof of possession) which is not checked by the deposit contract
+        deposit_message = DepositMessage(
+            pubkey=deposit.data.pubkey,
+            withdrawal_credentials=deposit.data.withdrawal_credentials,
+            amount=deposit.data.amount,
+        )
+        domain = compute_domain(DOMAIN_DEPOSIT)  # Fork-agnostic domain since deposits are valid across forks
+        signing_root = compute_signing_root(deposit_message, domain)
+        if not bls.Verify(pubkey, signing_root, deposit.data.signature):
+            return
+
+        # Add validator and balance entries
+        state.validators.append(get_validator_from_deposit(state, deposit))
+        state.balances.append(amount)
+        state.previous_epoch_participation.append(Bitvector[PARTICIPATION_FLAGS_LENGTH]())
+        state.current_epoch_participation.append(Bitvector[PARTICIPATION_FLAGS_LENGTH]())
+    else:
+        # Increase balance by deposit amount
+        index = ValidatorIndex(validator_pubkeys.index(pubkey))
+        increase_balance(state, index, amount)
+```
+
 #### Sync committee processing
 
 ```python
@@ -502,4 +548,4 @@ def process_final_updates(state: BeaconState) -> None:
         state.historical_roots.append(hash_tree_root(historical_batch))
     # Rotate current/previous epoch participation flags
     state.previous_epoch_participation = state.current_epoch_participation
-    state.current_epoch_participation = []
+    state.current_epoch_participation = [Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(state.validators))]

specs/lightclient/lightclient-fork.md

@@ -67,10 +67,8 @@ def upgrade_to_lightclient_patch(pre: phase0.BeaconState) -> BeaconState:
         # Slashings
         slashings=pre.slashings,
         # Attestations
-        # previous_epoch_attestations is cleared on upgrade. 
-        previous_epoch_participation=List[Bitvector[PARTICIPATION_FLAGS_LENGTH], VALIDATOR_REGISTRY_LIMIT](),
-        # empty in pre state, since the upgrade is performed just after an epoch boundary.
-        current_epoch_participation=List[Bitvector[PARTICIPATION_FLAGS_LENGTH], VALIDATOR_REGISTRY_LIMIT](),
+        previous_epoch_participation=[Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(pre.validators))],
+        current_epoch_participation=[Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(pre.validators))],
         # Finality
         justification_bits=pre.justification_bits,
         previous_justified_checkpoint=pre.previous_justified_checkpoint,

tests/core/pyspec/eth2spec/test/helpers/attestations.py

@@ -2,7 +2,7 @@ from lru import LRU
 
 from typing import List
 
-from eth2spec.test.context import expect_assertion_error, PHASE1
+from eth2spec.test.context import expect_assertion_error, PHASE1, LIGHTCLIENT_PATCH
 from eth2spec.test.helpers.state import state_transition_and_sign_block, next_epoch, next_slot
 from eth2spec.test.helpers.block import build_empty_block_for_next_slot
 from eth2spec.test.helpers.shard_transitions import get_shard_transition_of_committee
@@ -30,17 +30,25 @@ def run_attestation_processing(spec, state, attestation, valid=True):
         yield 'post', None
         return
 
-    current_epoch_count = len(state.current_epoch_attestations)
-    previous_epoch_count = len(state.previous_epoch_attestations)
+    if spec.fork != LIGHTCLIENT_PATCH:
+        current_epoch_count = len(state.current_epoch_attestations)
+        previous_epoch_count = len(state.previous_epoch_attestations)
 
     # process attestation
     spec.process_attestation(state, attestation)
 
     # Make sure the attestation has been processed
-    if attestation.data.target.epoch == spec.get_current_epoch(state):
-        assert len(state.current_epoch_attestations) == current_epoch_count + 1
+    if spec.fork != LIGHTCLIENT_PATCH:
+        if attestation.data.target.epoch == spec.get_current_epoch(state):
+            assert len(state.current_epoch_attestations) == current_epoch_count + 1
+        else:
+            assert len(state.previous_epoch_attestations) == previous_epoch_count + 1
     else:
-        assert len(state.previous_epoch_attestations) == previous_epoch_count + 1
+        for index in spec.get_attesting_indices(state, attestation.data, attestation.aggregation_bits):
+            if attestation.data.target.epoch == spec.get_current_epoch(state):
+                assert state.current_epoch_participation[index][spec.TIMELY_TARGET_FLAG]
+            else:
+                assert state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG]
 
     # yield post-state
     yield 'post', state