superstruct the AttesterSlashing (#5636)

* `superstruct` Attester Fork Variants

* Push a little further

* Deal with Encode / Decode of AttesterSlashing

* not so sure about this..

* Stop Encode/Decode Bounds from Propagating Out

* Tons of Changes..

* More Conversions to AttestationRef

* Add AsReference trait (#15)

* Add AsReference trait

* Fix some snafus

* Got it Compiling! :D

* Got Tests Building

* Get beacon chain tests compiling

---------

Co-authored-by: Michael Sproul <micsproul@gmail.com>

consensus/state_processing/src/per_block_processing/tests.rs

@@ -388,7 +388,12 @@ async fn invalid_attestation_no_committee_for_index() {
         .clone()
         .deconstruct()
         .0;
-    head_block.to_mut().body_mut().attestations_mut()[0]
+    head_block
+        .to_mut()
+        .body_mut()
+        .attestations_mut()
+        .next()
+        .unwrap()
         .data_mut()
         .index += 1;
     let mut ctxt = ConsensusContext::new(state.slot());
@@ -423,10 +428,21 @@ async fn invalid_attestation_wrong_justified_checkpoint() {
         .clone()
         .deconstruct()
         .0;
-    let old_justified_checkpoint = head_block.body().attestations()[0].data().source;
+    let old_justified_checkpoint = head_block
+        .body()
+        .attestations()
+        .next()
+        .unwrap()
+        .data()
+        .source;
     let mut new_justified_checkpoint = old_justified_checkpoint;
     new_justified_checkpoint.epoch += Epoch::new(1);
-    head_block.to_mut().body_mut().attestations_mut()[0]
+    head_block
+        .to_mut()
+        .body_mut()
+        .attestations_mut()
+        .next()
+        .unwrap()
         .data_mut()
         .source = new_justified_checkpoint;
 
@@ -467,7 +483,12 @@ async fn invalid_attestation_bad_aggregation_bitfield_len() {
         .clone()
         .deconstruct()
         .0;
-    *head_block.to_mut().body_mut().attestations_mut()[0]
+    *head_block
+        .to_mut()
+        .body_mut()
+        .attestations_mut()
+        .next()
+        .unwrap()
         .aggregation_bits_base_mut()
         .unwrap() = Bitfield::with_capacity(spec.target_committee_size).unwrap();
 
@@ -502,8 +523,13 @@ async fn invalid_attestation_bad_signature() {
         .clone()
         .deconstruct()
         .0;
-    *head_block.to_mut().body_mut().attestations_mut()[0].signature_mut() =
-        AggregateSignature::empty();
+    *head_block
+        .to_mut()
+        .body_mut()
+        .attestations_mut()
+        .next()
+        .unwrap()
+        .signature_mut() = AggregateSignature::empty();
 
     let mut ctxt = ConsensusContext::new(state.slot());
     let result = process_operations::process_attestations(
@@ -538,9 +564,14 @@ async fn invalid_attestation_included_too_early() {
         .clone()
         .deconstruct()
         .0;
-    let new_attesation_slot = head_block.body().attestations()[0].data().slot
+    let new_attesation_slot = head_block.body().attestations().next().unwrap().data().slot
         + Slot::new(MainnetEthSpec::slots_per_epoch());
-    head_block.to_mut().body_mut().attestations_mut()[0]
+    head_block
+        .to_mut()
+        .body_mut()
+        .attestations_mut()
+        .next()
+        .unwrap()
         .data_mut()
         .slot = new_attesation_slot;
 
@@ -581,9 +612,14 @@ async fn invalid_attestation_included_too_late() {
         .clone()
         .deconstruct()
         .0;
-    let new_attesation_slot = head_block.body().attestations()[0].data().slot
+    let new_attesation_slot = head_block.body().attestations().next().unwrap().data().slot
         - Slot::new(MainnetEthSpec::slots_per_epoch());
-    head_block.to_mut().body_mut().attestations_mut()[0]
+    head_block
+        .to_mut()
+        .body_mut()
+        .attestations_mut()
+        .next()
+        .unwrap()
         .data_mut()
         .slot = new_attesation_slot;
 
@@ -621,7 +657,12 @@ async fn invalid_attestation_target_epoch_slot_mismatch() {
         .clone()
         .deconstruct()
         .0;
-    head_block.to_mut().body_mut().attestations_mut()[0]
+    head_block
+        .to_mut()
+        .body_mut()
+        .attestations_mut()
+        .next()
+        .unwrap()
         .data_mut()
         .target
         .epoch += Epoch::new(1);
@@ -657,7 +698,7 @@ async fn valid_insert_attester_slashing() {
     let mut ctxt = ConsensusContext::new(state.slot());
     let result = process_operations::process_attester_slashings(
         &mut state,
-        &[attester_slashing],
+        [attester_slashing.to_ref()].into_iter(),
         VerifySignatures::True,
         &mut ctxt,
         &spec,
@@ -673,13 +714,20 @@ async fn invalid_attester_slashing_not_slashable() {
     let harness = get_harness::<MainnetEthSpec>(EPOCH_OFFSET, VALIDATOR_COUNT).await;
 
     let mut attester_slashing = harness.make_attester_slashing(vec![1, 2]);
-    attester_slashing.attestation_1 = attester_slashing.attestation_2.clone();
+    match &mut attester_slashing {
+        AttesterSlashing::Base(ref mut attester_slashing) => {
+            attester_slashing.attestation_1 = attester_slashing.attestation_2.clone();
+        }
+        AttesterSlashing::Electra(ref mut attester_slashing) => {
+            attester_slashing.attestation_1 = attester_slashing.attestation_2.clone();
+        }
+    }
 
     let mut state = harness.get_current_state();
     let mut ctxt = ConsensusContext::new(state.slot());
     let result = process_operations::process_attester_slashings(
         &mut state,
-        &[attester_slashing],
+        [attester_slashing.to_ref()].into_iter(),
         VerifySignatures::True,
         &mut ctxt,
         &spec,
@@ -701,16 +749,20 @@ async fn invalid_attester_slashing_1_invalid() {
     let harness = get_harness::<MainnetEthSpec>(EPOCH_OFFSET, VALIDATOR_COUNT).await;
 
     let mut attester_slashing = harness.make_attester_slashing(vec![1, 2]);
-    *attester_slashing
-        .attestation_1
-        .attesting_indices_base_mut()
-        .unwrap() = VariableList::from(vec![2, 1]);
+    match &mut attester_slashing {
+        AttesterSlashing::Base(ref mut attester_slashing) => {
+            attester_slashing.attestation_1.attesting_indices = VariableList::from(vec![2, 1]);
+        }
+        AttesterSlashing::Electra(ref mut attester_slashing) => {
+            attester_slashing.attestation_1.attesting_indices = VariableList::from(vec![2, 1]);
+        }
+    }
 
     let mut state = harness.get_current_state();
     let mut ctxt = ConsensusContext::new(state.slot());
     let result = process_operations::process_attester_slashings(
         &mut state,
-        &[attester_slashing],
+        [attester_slashing.to_ref()].into_iter(),
         VerifySignatures::True,
         &mut ctxt,
         &spec,
@@ -735,16 +787,20 @@ async fn invalid_attester_slashing_2_invalid() {
     let harness = get_harness::<MainnetEthSpec>(EPOCH_OFFSET, VALIDATOR_COUNT).await;
 
     let mut attester_slashing = harness.make_attester_slashing(vec![1, 2]);
-    *attester_slashing
-        .attestation_2
-        .attesting_indices_base_mut()
-        .unwrap() = VariableList::from(vec![2, 1]);
+    match &mut attester_slashing {
+        AttesterSlashing::Base(ref mut attester_slashing) => {
+            attester_slashing.attestation_2.attesting_indices = VariableList::from(vec![2, 1]);
+        }
+        AttesterSlashing::Electra(ref mut attester_slashing) => {
+            attester_slashing.attestation_2.attesting_indices = VariableList::from(vec![2, 1]);
+        }
+    }
 
     let mut state = harness.get_current_state();
     let mut ctxt = ConsensusContext::new(state.slot());
     let result = process_operations::process_attester_slashings(
         &mut state,
-        &[attester_slashing],
+        [attester_slashing.to_ref()].into_iter(),
         VerifySignatures::True,
         &mut ctxt,
         &spec,