Merge pull request #3232 from ethereum/capella-fc-cleanup

Remove `is_merge_transition_block` check since Capella

specs/capella/fork-choice.md

@@ -14,6 +14,8 @@
     - [`notify_forkchoice_updated`](#notify_forkchoice_updated)
 - [Helpers](#helpers)
   - [Extended `PayloadAttributes`](#extended-payloadattributes)
+- [Updated fork-choice handlers](#updated-fork-choice-handlers)
+  - [`on_block`](#on_block)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->
@@ -60,3 +62,56 @@ class PayloadAttributes(object):
     suggested_fee_recipient: ExecutionAddress
     withdrawals: Sequence[Withdrawal]  # [New in Capella]
 ```
+
+## Updated fork-choice handlers
+
+### `on_block`
+
+*Note*: The only modification is the deletion of the verification of merge transition block conditions.
+
+```python
+def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
+    """
+    Run ``on_block`` upon receiving a new block.
+    """
+    block = signed_block.message
+    # Parent block must be known
+    assert block.parent_root in store.block_states
+    # Make a copy of the state to avoid mutability issues
+    pre_state = copy(store.block_states[block.parent_root])
+    # Blocks cannot be in the future. If they are, their consideration must be delayed until they are in the past.
+    assert get_current_slot(store) >= block.slot
+
+    # Check that block is later than the finalized epoch slot (optimization to reduce calls to get_ancestor)
+    finalized_slot = compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)
+    assert block.slot > finalized_slot
+    # Check block is a descendant of the finalized block at the checkpoint finalized slot
+    finalized_checkpoint_block = get_checkpoint_block(
+        store,
+        block.parent_root,
+        store.finalized_checkpoint.epoch,
+    )
+    assert store.finalized_checkpoint.root == finalized_checkpoint_block
+
+    # Check the block is valid and compute the post-state
+    state = pre_state.copy()
+    block_root = hash_tree_root(block)
+    state_transition(state, signed_block, True)
+
+    # Add new block to the store
+    store.blocks[block_root] = block
+    # Add new state for this block to the store
+    store.block_states[block_root] = state
+
+    # Add proposer score boost if the block is timely
+    time_into_slot = (store.time - store.genesis_time) % SECONDS_PER_SLOT
+    is_before_attesting_interval = time_into_slot < SECONDS_PER_SLOT // INTERVALS_PER_SLOT
+    if get_current_slot(store) == block.slot and is_before_attesting_interval:
+        store.proposer_boost_root = hash_tree_root(block)
+
+    # Update checkpoints in store if necessary
+    update_checkpoints(store, state.current_justified_checkpoint, state.finalized_checkpoint)
+
+    # Eagerly compute unrealized justification and finality.
+    compute_pulled_up_tip(store, block_root)
+```

specs/deneb/fork-choice.md

@@ -98,10 +98,6 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
     block_root = hash_tree_root(block)
     state_transition(state, signed_block, True)
 
-    # Check the merge transition
-    if is_merge_transition_block(pre_state, block.body):
-        validate_merge_block(block)
-
     # Add new block to the store
     store.blocks[block_root] = block
     # Add new state for this block to the store