update get_crosslink_committee(...) to 0.8.0 and fix https://github.com/status-im/nim-beacon-chain/issues/307

beacon_chain/beacon_node.nim

@@ -469,7 +469,7 @@ proc handleAttestations(node: BeaconNode, head: BlockRef, slot: Slot) =
   node.blockPool.withState(node.stateCache, attestationHead):
     var cache = get_empty_per_epoch_cache()
     let epoch = compute_epoch_of_slot(slot)
-    for committee_index in 0'u64 ..< get_epoch_committee_count(state, epoch):
+    for committee_index in 0'u64 ..< get_committee_count(state, epoch):
       ## TODO verify that this is the correct mapping; it's consistent with
       ## other code
       let

beacon_chain/spec/beaconstate.nim

@@ -268,7 +268,7 @@ func get_attestation_data_slot*(state: BeaconState,
 func get_attestation_data_slot*(state: BeaconState,
     data: AttestationData): Slot =
   get_attestation_data_slot(
-    state, data, get_epoch_committee_count(state, data.target_epoch))
+    state, data, get_committee_count(state, data.target_epoch))
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.8.0/specs/core/0_beacon-chain.md#get_block_root_at_slot
 func get_block_root_at_slot*(state: BeaconState,

beacon_chain/spec/helpers.nim

@@ -80,8 +80,8 @@ func get_active_validator_indices*(state: BeaconState, epoch: Epoch):
     if is_active_validator(val, epoch):
       result.add idx.ValidatorIndex
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#get_epoch_committee_count
-func get_epoch_committee_count*(state: BeaconState, epoch: Epoch): uint64 =
+# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#get_committee_count
+func get_committee_count*(state: BeaconState, epoch: Epoch): uint64 =
   # Return the number of committees at ``epoch``.
   let active_validator_indices = get_active_validator_indices(state, epoch)
   clamp(
@@ -174,8 +174,8 @@ func get_domain*(
 func get_domain*(state: BeaconState, domain_type: DomainType): Domain =
   get_domain(state, domain_type, get_current_epoch(state))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#generate_seed
-func generate_seed*(state: BeaconState, epoch: Epoch): Eth2Digest =
+# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#get_seed
+func get_seed*(state: BeaconState, epoch: Epoch): Eth2Digest =
   # Generate a seed for the given ``epoch``.
 
   var seed_input : array[32*3, byte]

beacon_chain/spec/state_transition_block.nim

@@ -261,7 +261,7 @@ proc processAttestations(
       committee_count = if epoch in committee_count_cache:
           committee_count_cache[epoch]
         else:
-          get_epoch_committee_count(state, epoch)
+          get_committee_count(state, epoch)
     committee_count_cache[epoch] = committee_count
 
     # Spec content

beacon_chain/spec/state_transition_epoch.nim

@@ -219,7 +219,7 @@ func process_crosslinks(state: var BeaconState, stateCache: var StateCache) =
     # This issue comes up regularly -- iterating means an int type,
     # which then needs re-conversion back to specialized type.
     let epoch = epoch_int.Epoch
-    for offset in 0'u64 ..< get_epoch_committee_count(state, epoch):
+    for offset in 0'u64 ..< get_committee_count(state, epoch):
       let
         shard = (get_start_shard(state, epoch) + offset) mod SHARD_COUNT
         crosslink_committee =
@@ -325,7 +325,7 @@ func get_crosslink_deltas(state: BeaconState, cache: var StateCache):
     rewards = repeat(0'u64, len(state.validators))
     penalties = repeat(0'u64, len(state.validators))
   let epoch = get_previous_epoch(state)
-  for offset in 0'u64 ..< get_epoch_committee_count(state, epoch):
+  for offset in 0'u64 ..< get_committee_count(state, epoch):
     let
       shard = (get_start_shard(state, epoch) + offset) mod SHARD_COUNT
       crosslink_committee =

beacon_chain/spec/validator.nim

@@ -92,7 +92,7 @@ func get_previous_epoch*(state: BeaconState): Epoch =
 func get_shard_delta*(state: BeaconState, epoch: Epoch): uint64 =
   ## Return the number of shards to increment ``state.start_shard``
   ## during ``epoch``.
-  min(get_epoch_committee_count(state, epoch),
+  min(get_committee_count(state, epoch),
     (SHARD_COUNT - SHARD_COUNT div SLOTS_PER_EPOCH).uint64)
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.8.0/specs/core/0_beacon-chain.md#get_start_shard
@@ -136,14 +136,13 @@ func compute_committee(indices: seq[ValidatorIndex], seed: Eth2Digest,
     start.int .. (endIdx.int-1),
     indices[stateCache.crosslink_committee_cache[key][it]])
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#get_crosslink_committee
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.0/specs/core/0_beacon-chain.md#get_crosslink_committee
 func get_crosslink_committee*(state: BeaconState, epoch: Epoch, shard: Shard,
     stateCache: var StateCache): seq[ValidatorIndex] =
 
   doAssert shard >= 0'u64
   # This seems to be required, basically, to be true? But I'm not entirely sure
   #doAssert shard >= get_start_shard(state, epoch)
-  doAssert shard < SHARD_COUNT
 
   ## This is a somewhat more fragile, but high-ROI, caching setup --
   ## get_active_validator_indices() is slow to run in a loop and only
@@ -154,9 +153,9 @@ func get_crosslink_committee*(state: BeaconState, epoch: Epoch, shard: Shard,
 
   compute_committee(
     stateCache.active_validator_indices_cache[epoch],
-    generate_seed(state, epoch),
+    get_seed(state, epoch),
     (shard + SHARD_COUNT - get_start_shard(state, epoch)) mod SHARD_COUNT,
-    get_epoch_committee_count(state, epoch),
+    get_committee_count(state, epoch),
     stateCache
   )
 
@@ -177,11 +176,11 @@ func get_beacon_proposer_index*(state: BeaconState, stateCache: var StateCache):
   let
     epoch = get_current_epoch(state)
     committees_per_slot =
-      get_epoch_committee_count(state, epoch) div SLOTS_PER_EPOCH
+      get_committee_count(state, epoch) div SLOTS_PER_EPOCH
     offset = committees_per_slot * (state.slot mod SLOTS_PER_EPOCH)
     shard = (get_start_shard(state, epoch) + offset) mod SHARD_COUNT
     first_committee = get_crosslink_committee(state, epoch, shard, stateCache)
-    seed = generate_seed(state, epoch)
+    seed = get_seed(state, epoch)
 
   var
     i = 0

research/state_sim.nim

@@ -104,7 +104,7 @@ cli do(slots = 448,
         epoch = compute_epoch_of_slot(state.slot)
         scass = withTimerRet(timers[tShuffle]):
           mapIt(
-            0'u64 .. (get_epoch_committee_count(state, epoch) - 1),
+            0'u64 .. (get_committee_count(state, epoch) - 1),
             get_crosslink_committee(state, epoch,
               (it + get_start_shard(state, epoch)) mod SHARD_COUNT,
               cache))

tests/testutil.nim

@@ -145,7 +145,7 @@ proc find_shard_committee(
     state: BeaconState, validator_index: ValidatorIndex): auto =
   let epoch = compute_epoch_of_slot(state.slot)
   var cache = get_empty_per_epoch_cache()
-  for shard in 0'u64 ..< get_epoch_committee_count(state, epoch):
+  for shard in 0'u64 ..< get_committee_count(state, epoch):
     let committee = get_crosslink_committee(state, epoch,
       (shard + get_start_shard(state, epoch)) mod SHARD_COUNT, cache)
     if validator_index in committee: