Allow London blocks to contain pre-London uncles

In a combined rlp object for a block body.

Author: carver

eth/vm/forks/london/blocks.py

@@ -1,5 +1,6 @@
 import time
 from typing import (
+    List,
     Type,
     cast,
 )
@@ -25,6 +26,7 @@
 
 from eth.abc import (
     BlockHeaderAPI,
+    BlockHeaderSedesAPI,
     MiningHeaderAPI,
     ReceiptBuilderAPI,
     TransactionBuilderAPI,
@@ -37,6 +39,9 @@
     GENESIS_PARENT_HASH,
     BLANK_ROOT_HASH,
 )
+from eth.rlp.headers import (
+    BlockHeader,
+)
 from eth.rlp.sedes import (
     address,
     hash32,
@@ -160,11 +165,36 @@ def is_genesis(self) -> bool:
         return self.parent_hash == GENESIS_PARENT_HASH and self.block_number == 0
 
 
+class LondonBackwardsHeader(BlockHeaderSedesAPI):
+    """
+    An rlp sedes class for block headers.
+
+    It can serialize and deserialize *both* London and pre-London headers.
+    """
+
+    @classmethod
+    def serialize(cls, obj: BlockHeaderAPI) -> List[bytes]:
+        return obj.serialize(obj)
+
+    @classmethod
+    def deserialize(cls, encoded: List[bytes]) -> BlockHeaderAPI:
+        num_fields = len(encoded)
+        if num_fields == 16:
+            return LondonBlockHeader.deserialize(encoded)
+        elif num_fields == 15:
+            return BlockHeader.deserialize(encoded)
+        else:
+            raise ValueError(
+                "London & earlier can only handle headers of 15 or 16 fields. "
+                f"Got {num_fields} in {encoded!r}"
+            )
+
+
 class LondonBlock(BerlinBlock):
     transaction_builder: Type[TransactionBuilderAPI] = LondonTransactionBuilder
     receipt_builder: Type[ReceiptBuilderAPI] = LondonReceiptBuilder
     fields = [
         ('header', LondonBlockHeader),
         ('transactions', CountableList(transaction_builder)),
-        ('uncles', CountableList(LondonBlockHeader))
+        ('uncles', CountableList(LondonBackwardsHeader))
     ]

eth/vm/forks/london/headers.py

@@ -1,7 +1,6 @@
 from typing import (
     Any,
     Callable,
-    List,
     Optional,
 )
 
@@ -17,12 +16,8 @@
 )
 from eth.abc import (
     BlockHeaderAPI,
-    BlockHeaderSedesAPI,
 )
 from eth.constants import GENESIS_GAS_LIMIT
-from eth.rlp.headers import (
-    BlockHeader,
-)
 from eth.vm.forks.berlin.headers import (
     compute_berlin_difficulty,
     configure_header,
@@ -127,28 +122,3 @@ def create_header_from_parent(difficulty_fn: Callable[[BlockHeaderAPI, int], int
 )
 
 configure_london_header = configure_header(compute_london_difficulty)
-
-
-class LondonBackwardsHeader(BlockHeaderSedesAPI):
-    """
-    An rlp sedes class for block headers.
-
-    It can serialize and deserialize *both* London and pre-London headers.
-    """
-
-    @classmethod
-    def serialize(cls, obj: BlockHeaderAPI) -> List[bytes]:
-        return obj.serialize(obj)
-
-    @classmethod
-    def deserialize(cls, encoded: List[bytes]) -> BlockHeaderAPI:
-        num_fields = len(encoded)
-        if num_fields == 16:
-            return LondonBlockHeader.deserialize(encoded)
-        elif num_fields == 15:
-            return BlockHeader.deserialize(encoded)
-        else:
-            raise ValueError(
-                "London & earlier can only handle headers of 15 or 16 fields. "
-                f"Got {num_fields} in {encoded!r}"
-            )

eth/vm/header.py

@@ -1,4 +1,4 @@
-from eth.vm.forks.london.headers import LondonBackwardsHeader
+from eth.vm.forks.london.blocks import LondonBackwardsHeader
 
 HeaderSedes = LondonBackwardsHeader
 """