Add committee_len to attestation data

eth2/types/src/attestation_duty.rs

@@ -6,5 +6,5 @@ pub struct AttestationDuty {
     pub slot: Slot,
     pub shard: Shard,
     pub committee_index: usize,
-    pub comittee_size: usize,
+    pub committee_len: usize,
 }

eth2/types/src/beacon_state/epoch_cache.rs

@@ -92,6 +92,7 @@ impl EpochCache {
                         slot,
                         shard,
                         committee_index: k,
+                        committee_len: crosslink_committee.committee.len(),
                     };
                     attestation_duties[*validator_index] = Some(attestation_duty)
                 }

eth2/utils/boolean-bitfield/src/lib.rs

@@ -33,9 +33,11 @@ impl BooleanBitfield {
     }
 
     /// Create a new bitfield with the given length `initial_len` and all values set to `bit`.
-    pub fn from_elem(inital_len: usize, bit: bool) -> Self {
+    pub fn from_elem(initial_len: usize, bit: bool) -> Self {
+        // BitVec can panic if we don't set the len to be a multiple of 8.
+        let len = ((initial_len + 7) / 8) * 8;
         Self {
-            0: BitVec::from_elem(inital_len, bit),
+            0: BitVec::from_elem(len, bit),
         }
     }