From 8cd8bc7b0604d03511bb318ab2dc4c050e214562 Mon Sep 17 00:00:00 2001
From: Laurent Rineau <laurent.rineau@cgal.org>
Date: Sun, 4 Jun 2023 20:49:02 +0200
Subject: [PATCH] another fix of a race-condition

---
 .../include/CGAL/Spatial_lock_grid_3.h        |  2 +-
 .../include/CGAL/Regular_triangulation_3.h    | 20 +++++++++++++------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/STL_Extension/include/CGAL/Spatial_lock_grid_3.h b/STL_Extension/include/CGAL/Spatial_lock_grid_3.h
index b50211b0199..58737d76191 100644
--- a/STL_Extension/include/CGAL/Spatial_lock_grid_3.h
+++ b/STL_Extension/include/CGAL/Spatial_lock_grid_3.h
@@ -209,7 +209,7 @@ public:
     int index_x = static_cast<int>( (CGAL::to_double(point.x()) - m_bbox.xmin()) * m_resolution_x);
     //index_x = std::max( 0, std::min(index_x, m_num_grid_cells_per_axis - 1) );
     index_x =
-      (index_x < 0 ?
+      (index_x < 0 ? /// @TODO: use std::clamp
         0
         : (index_x >= m_num_grid_cells_per_axis ?
             m_num_grid_cells_per_axis - 1
diff --git a/Triangulation_3/include/CGAL/Regular_triangulation_3.h b/Triangulation_3/include/CGAL/Regular_triangulation_3.h
index 072a3795e94..bc999c178a9 100644
--- a/Triangulation_3/include/CGAL/Regular_triangulation_3.h
+++ b/Triangulation_3/include/CGAL/Regular_triangulation_3.h
@@ -2584,8 +2584,17 @@ remove(Vertex_handle v, bool *could_lock_zone)
     if(!vertex_validity_check(v, tds()))
       return true; // vertex is already gone from the TDS, nothing to do
 
-    Vertex_handle hint = v->cell()->vertex(0) == v ? v->cell()->vertex(1) : v->cell()->vertex(0);
-
+#ifndef CGAL_LINKED_WITH_TBB
+    using Vertex_handle_and_point = Vertex_handle;
+#endif // not CGAL_LINKED_WITH_TBB
+    Vertex_handle_and_point hint_and_point{v->cell()->vertex(0) == v ? v->cell()->vertex(1) : v->cell()->vertex(0)};
+#ifdef CGAL_LINKED_WITH_TBB
+    const Vertex_handle& hint = hint_and_point.vh;
+    const Weighted_point& hint_point_mem = hint_and_point.wpt;
+#else // not CGAL_LINKED_WITH_TBB
+    const Vertex_handle& hint = hint_and_point;
+    const Weighted_point& hint_point_mem = hint_and_point->point();
+#endif // not CGAL_LINKED_WITH_TBB
     Self tmp;
     Vertex_remover<Self> remover(tmp);
     removed = Tr_Base::remove(v, remover, could_lock_zone);
@@ -2612,13 +2621,12 @@ remove(Vertex_handle v, bool *could_lock_zone)
           // the hint.
           if(!vertex_validity_check(hint, tds()))
           {
-            hint = finite_vertices_begin();
+            hint_and_point = finite_vertices_begin();
             continue;
           }
 
           // We need to make sure that while are locking the position P1 := hint->point(), 'hint'
           // does not get its position changed to P2 != P1.
-          const Weighted_point hint_point_mem = hint->point();
 
           if(this->try_lock_point(hint_point_mem) && this->try_lock_point(wp))
           {
@@ -2628,7 +2636,7 @@ remove(Vertex_handle v, bool *could_lock_zone)
             if(!vertex_validity_check(hint, tds()) ||
                hint->point() != hint_point_mem)
             {
-              hint = finite_vertices_begin();
+              hint_and_point = finite_vertices_begin();
               this->unlock_all_elements();
               continue;
             }
@@ -2639,7 +2647,7 @@ remove(Vertex_handle v, bool *could_lock_zone)
             {
               success = true;
               if(hv != Vertex_handle())
-                hint = hv;
+                hint_and_point = hv;
             }
           }