From cc6d88962e4a22170361b576534246bd57974d80 Mon Sep 17 00:00:00 2001
From: Etan Kissling <etan@nimbus.team>
Date: Thu, 15 Aug 2024 01:48:39 +0200
Subject: [PATCH] Treat putting empty data in hexary trie as deleting data
 (#720)

Other implementations of MPT delete entries when attempting to put empty
value, because empty value cannot exist in RLP. We should match the
behaviour.

- https://github.com/ethereum/py-trie/pull/109

Also cross-checked with Geth and Ethereumjs implementations.
---
 eth/trie/hexary.nim | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/eth/trie/hexary.nim b/eth/trie/hexary.nim
index ec9f638..2144111 100644
--- a/eth/trie/hexary.nim
+++ b/eth/trie/hexary.nim
@@ -653,6 +653,12 @@ proc mergeAt(self: var HexaryTrie, orig: Rlp, origHash: KeccakHash,
     return r.finish
 
 proc put*(self: var HexaryTrie; key, value: openArray[byte]) =
+  if value.len == 0:
+    # Empty nodes are not allowed as `[]` is not a valid RLP encoding
+    # https://github.com/ethereum/py-trie/pull/109
+    self.del key
+    return
+
   let root = self.root.hash
 
   var rootBytes = self.db.get(root.data)