From 93e8257255d32ae79c1d2a0f077f111ee46d6392 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Loriot?= <sebastien.loriot@cgal.org>
Date: Thu, 3 Apr 2025 11:56:06 +0200
Subject: [PATCH] workaround possible optimisation that would alter the value
 of the erase_counter

The code is still not legal but works in practise.

fix similar to 5853673267
---
 STL_Extension/include/CGAL/Compact_container.h | 18 ++++++++++++++++++
 .../CGAL/Concurrent_compact_container.h        | 18 ++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/STL_Extension/include/CGAL/Compact_container.h b/STL_Extension/include/CGAL/Compact_container.h
index 9b6cb202e93..be4ff0f757c 100644
--- a/STL_Extension/include/CGAL/Compact_container.h
+++ b/STL_Extension/include/CGAL/Compact_container.h
@@ -177,6 +177,8 @@ namespace internal {
     template <typename Element>
     static void set_erase_counter(Element &, unsigned int) {}
     template <typename Element>
+    static void restore_erase_counter(Element*, unsigned int) {}
+    template <typename Element>
     static void increment_erase_counter(Element &) {}
   };
 
@@ -192,12 +194,24 @@ namespace internal {
       return e.erase_counter();
     }
 
+    template <typename Element>
+    static unsigned int erase_counter(Element* e)
+    {
+      return e->erase_counter();
+    }
+
     template <typename Element>
     static void set_erase_counter(Element &e, unsigned int c)
     {
       e.set_erase_counter(c);
     }
 
+    template <typename Element>
+    static void restore_erase_counter(Element* e, unsigned int c)
+    {
+      e->set_erase_counter(c);
+    }
+
     template <typename Element>
     static void increment_erase_counter(Element &e)
     {
@@ -402,9 +416,11 @@ public:
     pointer ret = free_list;
     free_list = clean_pointee(ret);
     const auto ts = Time_stamper::time_stamp(ret);
+    const auto ec = EraseCounterStrategy<T>::erase_counter(ret);
     new (ret) value_type(std::forward<Args>(args)...);
     Time_stamper::restore_timestamp(ret, ts);
     Time_stamper::set_time_stamp(ret, time_stamp);
+    EraseCounterStrategy<T>::restore_erase_counter(ret, ec);
     CGAL_assertion(type(ret) == USED);
     ++size_;
     return iterator(ret, 0);
@@ -435,8 +451,10 @@ public:
     CGAL_precondition(type(ptr) == USED);
     EraseCounterStrategy<T>::increment_erase_counter(*x);
     const auto ts = Time_stamper::time_stamp(ptr);
+    const auto ec = EraseCounterStrategy<T>::erase_counter(*x);
     std::allocator_traits<allocator_type>::destroy(alloc, ptr);
     Time_stamper::restore_timestamp(ptr, ts);
+    EraseCounterStrategy<T>::restore_erase_counter(ptr, ec);
 
     put_on_free_list(ptr);
     --size_;
diff --git a/STL_Extension/include/CGAL/Concurrent_compact_container.h b/STL_Extension/include/CGAL/Concurrent_compact_container.h
index 653ea056e74..0672e8b8117 100644
--- a/STL_Extension/include/CGAL/Concurrent_compact_container.h
+++ b/STL_Extension/include/CGAL/Concurrent_compact_container.h
@@ -80,6 +80,8 @@ namespace CCC_internal {
     template <typename Element>
     static void set_erase_counter(Element &, unsigned int) {}
     template <typename Element>
+    static void restore_erase_counter(Element*, unsigned int) {}
+    template <typename Element>
     static void increment_erase_counter(Element &) {}
   };
 
@@ -95,12 +97,24 @@ namespace CCC_internal {
       return e.erase_counter();
     }
 
+    template <typename Element>
+    static unsigned int erase_counter(Element* e)
+    {
+      return e->erase_counter();
+    }
+
     template <typename Element>
     static void set_erase_counter(Element &e, unsigned int c)
     {
       e.set_erase_counter(c);
     }
 
+    template <typename Element>
+    static void restore_erase_counter(Element* e, unsigned int c)
+    {
+      e->set_erase_counter(c);
+    }
+
     template <typename Element>
     static void increment_erase_counter(Element &e)
     {
@@ -353,9 +367,11 @@ public:
     pointer ret = init_insert(fl);
     auto erase_counter = EraseCounterStrategy<T>::erase_counter(*ret);
     const auto ts = Time_stamper::time_stamp(ret);
+    const auto ec = EraseCounterStrategy<T>::erase_counter(ret);
     new (ret) value_type(std::forward<Args>(args)...);
     Time_stamper::restore_timestamp(ret, ts);
     EraseCounterStrategy<T>::set_erase_counter(*ret, erase_counter);
+    EraseCounterStrategy<T>::restore_erase_counter(ret, ec);
     return finalize_insert(ret, fl);
   }
 
@@ -386,8 +402,10 @@ private:
 
     auto ptr = &*x;
     const auto ts = Time_stamper::time_stamp(ptr);
+    const auto ec = EraseCounterStrategy<T>::erase_counter(*x);
     std::allocator_traits<allocator_type>::destroy(m_alloc, &*x);
     Time_stamper::restore_timestamp(ptr, ts);
+    EraseCounterStrategy<T>::restore_erase_counter(ptr, ec);
 
     put_on_free_list(&*x, fl);
   }