From ce987c4a64d392af1b6c33d4ec010cda4e10a42c Mon Sep 17 00:00:00 2001
From: Hsiao-Wei Wang <hsiaowei.eth@gmail.com>
Date: Fri, 27 Jan 2023 09:12:39 +0100
Subject: [PATCH] Delete `is_merge_transition_block` check from Capella

---
 specs/capella/fork-choice.md | 55 ++++++++++++++++++++++++++++++++++++
 specs/eip4844/fork-choice.md |  4 ---
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/specs/capella/fork-choice.md b/specs/capella/fork-choice.md
index 0e0a393c3..c08be1c3f 100644
--- a/specs/capella/fork-choice.md
+++ b/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
+    assert get_ancestor(store, block.parent_root, finalized_slot) == store.finalized_checkpoint.root
+
+    # Check the block is valid and compute the post-state
+    state = pre_state.copy()
+    state_transition(state, signed_block, True)
+
+    # Add new block to the store
+    store.blocks[hash_tree_root(block)] = block
+    # Add new state for this block to the store
+    store.block_states[hash_tree_root(block)] = 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 justified checkpoint
+    if state.current_justified_checkpoint.epoch > store.justified_checkpoint.epoch:
+        if state.current_justified_checkpoint.epoch > store.best_justified_checkpoint.epoch:
+            store.best_justified_checkpoint = state.current_justified_checkpoint
+        if should_update_justified_checkpoint(store, state.current_justified_checkpoint):
+            store.justified_checkpoint = state.current_justified_checkpoint
+
+    # Update finalized checkpoint
+    if state.finalized_checkpoint.epoch > store.finalized_checkpoint.epoch:
+        store.finalized_checkpoint = state.finalized_checkpoint
+        store.justified_checkpoint = state.current_justified_checkpoint
+```
diff --git a/specs/eip4844/fork-choice.md b/specs/eip4844/fork-choice.md
index 8dea28ded..865443e04 100644
--- a/specs/eip4844/fork-choice.md
+++ b/specs/eip4844/fork-choice.md
@@ -108,10 +108,6 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
     state = pre_state.copy()
     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[hash_tree_root(block)] = block
     # Add new state for this block to the store