From 8abc975c070c9def754fac7a1aa828d55a6ec412 Mon Sep 17 00:00:00 2001
From: Pasukhin Dmitry <dpasukhi@opencascade.com>
Date: Fri, 14 Aug 2026 14:20:54 +0100
Subject: [PATCH] Revert "Mesh - Fix iterator invalidation in Delaun
 triangle-kill cascade (#1450)" (#1459)

This reverts commit 7d2efad9c8a9a57ea96c4c8587134b34dd503cd8.
---
 .../TKMesh/BRepMesh/BRepMesh_Delaun.cxx       | 41 ++++---------------
 1 file changed, 8 insertions(+), 33 deletions(-)

diff --git a/src/ModelingAlgorithms/TKMesh/BRepMesh/BRepMesh_Delaun.cxx b/src/ModelingAlgorithms/TKMesh/BRepMesh/BRepMesh_Delaun.cxx
index 816177178d..faaa1abff7 100644
--- a/src/ModelingAlgorithms/TKMesh/BRepMesh/BRepMesh_Delaun.cxx
+++ b/src/ModelingAlgorithms/TKMesh/BRepMesh/BRepMesh_Delaun.cxx
@@ -142,19 +142,6 @@ public:
 private:
   NCollection_LinearVector<Frame> myFrames; // Container of frames.
 };
-
-//! Returns a snapshot of the neighbor link ids of the given node.
-NCollection_Array1<int> getSnapshotsOfNeighborLinkIds(
-  const IMeshData::ListOfInteger& theNeighborLinkIds)
-{
-  NCollection_Array1<int> aNeighborLinkIdsArray(theNeighborLinkIds.Size());
-  size_t                  anIndex = 0;
-  for (const auto& aLinkId : theNeighborLinkIds)
-  {
-    aNeighborLinkIdsArray.ChangeAt(anIndex++) = aLinkId;
-  }
-  return aNeighborLinkIdsArray;
-}
 } // anonymous namespace
 
 //=================================================================================================
@@ -1556,24 +1543,18 @@ void BRepMesh_Delaun::killTrianglesAroundVertex(
   IMeshData::MapOfIntegerInteger&     theLoopEdges,
   IMeshData::VectorOfInteger&         theVictimNodes)
 {
-  // Snapshot the neighbor link ids before iterating
-  const NCollection_Array1<int> aNeighborLinkIdsArray =
-    getSnapshotsOfNeighborLinkIds(myMeshData->LinksConnectedTo(theZombieNodeId));
+  IMeshData::ListOfInteger::Iterator aNeighborsIt = myMeshData->LinksConnectedTo(theZombieNodeId);
 
   // Try to infect neighbor nodes
-  for (const int aNeighborLinkId : aNeighborLinkIdsArray)
+  for (; aNeighborsIt.More(); aNeighborsIt.Next())
   {
+    const int& aNeighborLinkId = aNeighborsIt.Value();
     if (theSurvivedLinks.Contains(aNeighborLinkId))
     {
       continue;
     }
 
     const BRepMesh_Edge& aNeighborLink = GetEdge(aNeighborLinkId);
-    if (aNeighborLink.Movability() == BRepMesh_Deleted)
-    {
-      continue;
-    }
-
     if (aNeighborLink.Movability() == BRepMesh_Frontier)
     {
       // Though, if it lies onto the polygon boundary -
@@ -1702,19 +1683,13 @@ void BRepMesh_Delaun::killTrianglesOnIntersectingLinks(
 
   killLinkTriangles(theLinkToCheckId, theLoopEdges);
 
-  // Snapshot the neighbor link ids before iterating
-  const NCollection_Array1<int> aNeighborLinkIds =
-    getSnapshotsOfNeighborLinkIds(myMeshData->LinksConnectedTo(theEndPoint));
+  IMeshData::ListOfInteger::Iterator aNeighborsIt(myMeshData->LinksConnectedTo(theEndPoint));
 
-  for (const int aNeighborLinkId : aNeighborLinkIds)
+  for (; aNeighborsIt.More(); aNeighborsIt.Next())
   {
-    const BRepMesh_Edge& aNeighborLink = GetEdge(aNeighborLinkId);
-    if (aNeighborLink.Movability() == BRepMesh_Deleted)
-    {
-      continue;
-    }
-
-    int anOtherNode = aNeighborLink.FirstNode();
+    const int&           aNeighborLinkId = aNeighborsIt.Value();
+    const BRepMesh_Edge& aNeighborLink   = GetEdge(aNeighborLinkId);
+    int                  anOtherNode     = aNeighborLink.FirstNode();
     if (anOtherNode == theEndPoint)
     {
       anOtherNode = aNeighborLink.LastNode();