replace deprecated toSet(...) with toHashSet(...); replace implicit with more explicit default constructor for readability

beacon_chain/spec/crypto.nim

@@ -181,7 +181,7 @@ func bls_verify*(
     # TODO bls_verify_multiple(...) used to have this workaround, and now it
     # lives here. No matter the signature, there's also no meaningful way to
     # verify it -- it's a kind of vacuous truth. No pubkey/sig pairs.
-    if pubkey == ValidatorPubKey():
+    if pubkey == default(ValidatorPubKey):
       return true
 
     sig.blsValue.verify(msg, domain, pubkey.blsValue)

beacon_chain/spec/state_transition_block.nim

@@ -245,8 +245,8 @@ proc process_attester_slashing*(
     ## verify_indexed_attestation, but go by spec unless there
     ## is compelling perf evidence otherwise.
     for index in sorted(toSeq(intersection(
-        toSet(attestation_1.attesting_indices),
-        toSet(attestation_2.attesting_indices)).items), system.cmp):
+        toHashSet(attestation_1.attesting_indices),
+        toHashSet(attestation_2.attesting_indices)).items), system.cmp):
       if is_slashable_validator(
           state.validators[index.int], get_current_epoch(state)):
         slash_validator(state, index.ValidatorIndex, stateCache)
@@ -384,9 +384,9 @@ proc processBlock*(
 
   # Adds nontrivial additional computation, but only does so when metrics
   # enabled.
-  beacon_current_live_validators.set(toSet(
+  beacon_current_live_validators.set(toHashSet(
     mapIt(state.current_epoch_attestations, it.proposerIndex)).len.int64)
-  beacon_previous_live_validators.set(toSet(
+  beacon_previous_live_validators.set(toHashSet(
     mapIt(state.previous_epoch_attestations, it.proposerIndex)).len.int64)
 
   if not process_block_header(state, blck, flags, stateCache):

beacon_chain/spec/state_transition_epoch.nim

@@ -128,7 +128,7 @@ proc process_justification_and_finalization*(
 
   # This is a somewhat expensive approach
   let active_validator_indices =
-    toSet(mapIt(
+    toHashSet(mapIt(
       get_active_validator_indices(state, get_current_epoch(state)), it.int))
 
   let matching_target_attestations_previous =
@@ -147,11 +147,11 @@ proc process_justification_and_finalization*(
   trace "Non-attesting indices in previous epoch",
     missing_all_validators=
       difference(active_validator_indices,
-        toSet(mapIt(get_attesting_indices(state,
+        toHashSet(mapIt(get_attesting_indices(state,
           matching_target_attestations_previous, stateCache), it.int))),
     missing_unslashed_validators=
       difference(active_validator_indices,
-        toSet(mapIt(get_unslashed_attesting_indices(state,
+        toHashSet(mapIt(get_unslashed_attesting_indices(state,
           matching_target_attestations_previous, stateCache), it.int))),
     prev_attestations_len=len(state.previous_epoch_attestations),
     cur_attestations_len=len(state.current_epoch_attestations),