From f434cc291892e826c675056bc5e770add7e004b3 Mon Sep 17 00:00:00 2001
From: Shawn Xu <xu107288696@gmail.com>
Date: Fri, 17 Oct 2025 15:53:49 -0700
Subject: [PATCH] Allow AccumulatorStack::size to point to one past the end

this is guaranteed to be correct since we access the last element with `size - 1`

closes https://github.com/official-stockfish/Stockfish/pull/6368

fixes https://github.com/official-stockfish/Stockfish/issues/6367

no functional change
---
 src/nnue/nnue_accumulator.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nnue/nnue_accumulator.cpp b/src/nnue/nnue_accumulator.cpp
index d13105aa4..3096758b9 100644
--- a/src/nnue/nnue_accumulator.cpp
+++ b/src/nnue/nnue_accumulator.cpp
@@ -75,7 +75,7 @@ void AccumulatorStack::reset() noexcept {
 }
 
 void AccumulatorStack::push(const DirtyPiece& dirtyPiece) noexcept {
-    assert(size + 1 < accumulators.size());
+    assert(size < accumulators.size());
     accumulators[size].reset(dirtyPiece);
     size++;
 }