From f8c283410e0465fe44d733a219019f77c418cc21 Mon Sep 17 00:00:00 2001
From: CPerezz <cperezz19@pm.me>
Date: Sun, 19 Apr 2026 22:15:01 +0200
Subject: [PATCH] trie/bintrie: drop unused freeInternals and freeStems

Only freeHashed is written to (via freeHashedNode); the internal and
stem lists are declared, consumed in alloc paths, and copied in
NodeStore.Copy, but no callsite ever appends to them. Under current
semantics (no delete, stem-split keeps the old stem deeper in the
tree) there is no path that would free an internal or stem slot, so
the recycle branch was dead code. Drop it to avoid misleading future
contributors; the infrastructure is easy to restore if a delete path
is ever added.
---
 trie/bintrie/node_store.go | 29 +++++------------------------
 1 file changed, 5 insertions(+), 24 deletions(-)

diff --git a/trie/bintrie/node_store.go b/trie/bintrie/node_store.go
index 8f19c00fc5..728436ac12 100644
--- a/trie/bintrie/node_store.go
+++ b/trie/bintrie/node_store.go
@@ -36,10 +36,11 @@ type NodeStore struct {
 
 	root nodeRef
 
-	// Free lists for recycling deleted node slots.
-	freeInternals []uint32
-	freeStems     []uint32
-	freeHashed    []uint32
+	// Free list for recycling hashed-node slots after resolve. Internal and
+	// stem nodes are never freed under current semantics (no delete path,
+	// stem-split keeps the old stem at a deeper position), so they don't
+	// have free lists.
+	freeHashed []uint32
 }
 
 func NewNodeStore() *NodeStore {
@@ -47,12 +48,6 @@ func NewNodeStore() *NodeStore {
 }
 
 func (s *NodeStore) allocInternal() uint32 {
-	if n := len(s.freeInternals); n > 0 {
-		idx := s.freeInternals[n-1]
-		s.freeInternals = s.freeInternals[:n-1]
-		*s.getInternal(idx) = InternalNode{}
-		return idx
-	}
 	idx := s.internalCount
 	chunkIdx := idx / storeChunkSize
 	if uint32(len(s.internalChunks)) <= chunkIdx {
@@ -82,12 +77,6 @@ func (s *NodeStore) newInternalRef(depth int) nodeRef {
 }
 
 func (s *NodeStore) allocStem() uint32 {
-	if n := len(s.freeStems); n > 0 {
-		idx := s.freeStems[n-1]
-		s.freeStems = s.freeStems[:n-1]
-		*s.getStem(idx) = StemNode{}
-		return idx
-	}
 	idx := s.stemCount
 	chunkIdx := idx / storeChunkSize
 	if uint32(len(s.stemChunks)) <= chunkIdx {
@@ -186,14 +175,6 @@ func (s *NodeStore) Copy() *NodeStore {
 		cp := *chunk
 		ns.hashedChunks[i] = &cp
 	}
-	if len(s.freeInternals) > 0 {
-		ns.freeInternals = make([]uint32, len(s.freeInternals))
-		copy(ns.freeInternals, s.freeInternals)
-	}
-	if len(s.freeStems) > 0 {
-		ns.freeStems = make([]uint32, len(s.freeStems))
-		copy(ns.freeStems, s.freeStems)
-	}
 	if len(s.freeHashed) > 0 {
 		ns.freeHashed = make([]uint32, len(s.freeHashed))
 		copy(ns.freeHashed, s.freeHashed)