From 00f9a28729e3c4c0c18efecb99d19dd647592bc4 Mon Sep 17 00:00:00 2001
From: Michael Herzog <mh@edelweissgames.com>
Date: Fri, 28 Nov 2025 15:51:19 +0100
Subject: [PATCH] Fixed HashSet compaction count after mid-compact growth

Ensure HashSetBase::Compact() preserves _elementsCount even when EnsureCapacity() triggers during compaction. The growth path resets the counter; we now cache the original count and restore it after moving all buckets so Count() stays correct in heavy-collision scenarios.
---
 Source/Engine/Core/Collections/HashSetBase.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Source/Engine/Core/Collections/HashSetBase.h b/Source/Engine/Core/Collections/HashSetBase.h
index 96adabf79..58f1702c2 100644
--- a/Source/Engine/Core/Collections/HashSetBase.h
+++ b/Source/Engine/Core/Collections/HashSetBase.h
@@ -408,6 +408,7 @@ protected:
         }
         else
         {
+            const int32 elementsCount = _elementsCount;
             // Rebuild entire table completely
             const int32 oldSize = _size;
             AllocationData oldAllocation;
@@ -437,6 +438,7 @@ protected:
             }
             for (int32 i = 0; i < oldSize; ++i)
                 oldData[i].Free();
+            _elementsCount = elementsCount;
         }
         _deletedCount = 0;
     }