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* [gcc r13-8570] libstdc++: Destroy allocators in re-inserted container nodes [PR114401]
@ 2024-04-03 10:46 Jonathan Wakely
  0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2024-04-03 10:46 UTC (permalink / raw)
  To: gcc-cvs, libstdc++-cvs

https://gcc.gnu.org/g:47ebdbe5bf71d9eb260359b6aceb5cb071d97acd

commit r13-8570-g47ebdbe5bf71d9eb260359b6aceb5cb071d97acd
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Mar 21 13:25:15 2024 +0000

    libstdc++: Destroy allocators in re-inserted container nodes [PR114401]
    
    The allocator objects in container node handles were not being destroyed
    after the node was re-inserted into a container. They are stored in a
    union and so need to be explicitly destroyed when the node becomes
    empty. The containers were zeroing the node handle's pointer, which
    makes it empty, causing the handle's destructor to think there's nothing
    to clean up.
    
    Add a new member function to the node handle which destroys the
    allocator and zeros the pointer. Change the containers to call that
    instead of just changing the pointer manually.
    
    We can also remove the _M_empty member of the union which is not
    necessary.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/114401
            * include/bits/hashtable.h (_Hashtable::_M_reinsert_node): Call
            release() on node handle instead of just zeroing its pointer.
            (_Hashtable::_M_reinsert_node_multi): Likewise.
            (_Hashtable::_M_merge_unique): Likewise.
            (_Hashtable::_M_merge_multi): Likewise.
            * include/bits/node_handle.h (_Node_handle_common::release()):
            New member function.
            (_Node_handle_common::_Optional_alloc::_M_empty): Remove
            unnecessary union member.
            (_Node_handle_common): Declare _Hashtable as a friend.
            * include/bits/stl_tree.h (_Rb_tree::_M_reinsert_node_unique):
            Call release() on node handle instead of just zeroing its
            pointer.
            (_Rb_tree::_M_reinsert_node_equal): Likewise.
            (_Rb_tree::_M_reinsert_node_hint_unique): Likewise.
            (_Rb_tree::_M_reinsert_node_hint_equal): Likewise.
            * testsuite/23_containers/multiset/modifiers/114401.cc: New test.
            * testsuite/23_containers/set/modifiers/114401.cc: New test.
            * testsuite/23_containers/unordered_multiset/modifiers/114401.cc: New test.
            * testsuite/23_containers/unordered_set/modifiers/114401.cc: New test.
    
    (cherry picked from commit c2e28df90a1640cebadef6c6c8ab5ea964071bb1)

Diff:
---
 libstdc++-v3/include/bits/hashtable.h              |  10 +-
 libstdc++-v3/include/bits/node_handle.h            |  19 +++-
 libstdc++-v3/include/bits/stl_tree.h               |  10 +-
 .../23_containers/multiset/modifiers/114401.cc     | 125 ++++++++++++++++++++
 .../23_containers/set/modifiers/114401.cc          | 125 ++++++++++++++++++++
 .../unordered_multiset/modifiers/114401.cc         | 126 +++++++++++++++++++++
 .../unordered_set/modifiers/114401.cc              | 126 +++++++++++++++++++++
 7 files changed, 528 insertions(+), 13 deletions(-)

diff --git a/libstdc++-v3/include/bits/hashtable.h b/libstdc++-v3/include/bits/hashtable.h
index dd3e655866a..1b5d0a7f42f 100644
--- a/libstdc++-v3/include/bits/hashtable.h
+++ b/libstdc++-v3/include/bits/hashtable.h
@@ -996,7 +996,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // DR 1189.
       // reserve, if present, comes from _Rehash_base.
 
-#if __cplusplus > 201402L
+#if __cplusplus > 201404L
       /// Re-insert an extracted node into a container with unique keys.
       insert_return_type
       _M_reinsert_node(node_type&& __nh)
@@ -1021,7 +1021,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	      {
 		__ret.position
 		  = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
-		__nh._M_ptr = nullptr;
+		__nh.release();
 		__ret.inserted = true;
 	      }
 	  }
@@ -1041,7 +1041,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	auto __code = this->_M_hash_code(__k);
 	auto __ret
 	  = _M_insert_multi_node(__hint._M_cur, __code, __nh._M_ptr);
-	__nh._M_ptr = nullptr;
+	__nh.release();
 	return __ret;
       }
 
@@ -1123,7 +1123,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		{
 		  auto __nh = __src.extract(__pos);
 		  _M_insert_unique_node(__bkt, __code, __nh._M_ptr, __n_elt);
-		  __nh._M_ptr = nullptr;
+		  __nh.release();
 		  __n_elt = 1;
 		}
 	      else if (__n_elt != 1)
@@ -1150,7 +1150,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		= _M_src_hash_code(__src.hash_function(), __k, *__pos._M_cur);
 	      auto __nh = __src.extract(__pos);
 	      __hint = _M_insert_multi_node(__hint, __code, __nh._M_ptr)._M_cur;
-	      __nh._M_ptr = nullptr;
+	      __nh.release();
 	    }
 	}
 #endif // C++17
diff --git a/libstdc++-v3/include/bits/node_handle.h b/libstdc++-v3/include/bits/node_handle.h
index 8904a5ac496..79afa547ec4 100644
--- a/libstdc++-v3/include/bits/node_handle.h
+++ b/libstdc++-v3/include/bits/node_handle.h
@@ -168,6 +168,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	_M_ptr = nullptr;
       }
 
+      // Destroys the allocator. Does not deallocate or destroy the node.
+      // Precondition: !empty()
+      // Postcondition: empty()
+      void
+      release() noexcept
+      {
+	_M_alloc.release();
+	_M_ptr = nullptr;
+      }
+
     protected:
       typename _AllocTraits::pointer _M_ptr;
 
@@ -219,9 +229,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  return __tmp;
 	}
 
-	struct _Empty { };
-
-	[[__no_unique_address__]] _Empty     _M_empty;
 	[[__no_unique_address__]] _NodeAlloc _M_alloc;
       };
 
@@ -231,6 +238,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	       typename _Compare, typename _ValueAlloc>
 	friend class _Rb_tree;
 
+      template<typename _Key2, typename _Value2, typename _ValueAlloc,
+	       typename _ExtractKey, typename _Equal,
+	       typename _Hash, typename _RangeHash, typename _Unused,
+	       typename _RehashPolicy, typename _Traits>
+	friend class _Hashtable;
+
       /// @endcond
     };
 
diff --git a/libstdc++-v3/include/bits/stl_tree.h b/libstdc++-v3/include/bits/stl_tree.h
index f870f3dfa53..c3ecbeb1379 100644
--- a/libstdc++-v3/include/bits/stl_tree.h
+++ b/libstdc++-v3/include/bits/stl_tree.h
@@ -1435,7 +1435,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _M_move_assign(_Rb_tree&, false_type);
 #endif
 
-#if __cplusplus > 201402L
+#if __cplusplus > 201404L
     public:
       /// Re-insert an extracted node.
       insert_return_type
@@ -1453,7 +1453,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	      {
 		__ret.position
 		  = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
-		__nh._M_ptr = nullptr;
+		__nh.release();
 		__ret.inserted = true;
 	      }
 	    else
@@ -1481,7 +1481,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	      __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
 	    else
 	      __ret = _M_insert_equal_lower_node(__nh._M_ptr);
-	    __nh._M_ptr = nullptr;
+	    __nh.release();
 	  }
 	return __ret;
       }
@@ -1500,7 +1500,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    if (__res.second)
 	      {
 		__ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
-		__nh._M_ptr = nullptr;
+		__nh.release();
 	      }
 	    else
 	      __ret = iterator(__res.first);
@@ -1523,7 +1523,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	      __ret = _M_insert_node(__res.first, __res.second, __nh._M_ptr);
 	    else
 	      __ret = _M_insert_equal_lower_node(__nh._M_ptr);
-	    __nh._M_ptr = nullptr;
+	    __nh.release();
 	  }
 	return __ret;
       }
diff --git a/libstdc++-v3/testsuite/23_containers/multiset/modifiers/114401.cc b/libstdc++-v3/testsuite/23_containers/multiset/modifiers/114401.cc
new file mode 100644
index 00000000000..630e18e287c
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/multiset/modifiers/114401.cc
@@ -0,0 +1,125 @@
+// { dg-do run { target c++17 } }
+
+// PR libstdc++/114401 allocator destructor omitted when reinserting node_handle
+
+#include <set>
+#include <memory>
+#include <testsuite_hooks.h>
+
+template<typename T>
+struct Alloc
+{
+  using value_type = T;
+  using propagate_on_container_copy_assignment = std::true_type;
+  using propagate_on_container_move_assignment = std::true_type;
+  using propagate_on_container_swap = std::true_type;
+
+  Alloc(int identity) : id(std::make_shared<int>(identity)) { }
+
+  template<typename U>
+    Alloc(const Alloc<U> a) : id(a.id) { }
+
+  T* allocate(std::size_t n) { return std::allocator<T>().allocate(n); }
+  void deallocate(T* p, std::size_t n) { std::allocator<T>().deallocate(p, n); }
+
+  template<typename U>
+    friend bool
+    operator==(const Alloc& a, const Alloc<U>& a2)
+    { return a.id == a2.id; }
+
+  template<typename U>
+    friend bool
+    operator!=(const Alloc& a, const Alloc<U>& a2)
+    { return !(a == a2); }
+
+  std::shared_ptr<int> id;
+};
+
+using test_type = std::multiset<int, std::less<int>, Alloc<int>>;
+
+void
+test_node_ops()
+{
+  test_type s1({1,3,5}, Alloc<int>(1));
+  test_type s2({2,4,6,8}, Alloc<int>(2));
+  VERIFY( s1.get_allocator() != s2.get_allocator() );
+
+  auto node_a = s1.extract(1);
+  VERIFY( ! node_a.empty() );
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+
+  node_a = std::move(node_a); // self-move
+  VERIFY( node_a.empty() );
+
+  swap(node_a, node_a); // self-swap
+  VERIFY( node_a.empty() );
+
+  auto node_b = s2.extract(2);
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  node_a = std::move(node_b); // empty = !empty
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(!empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  node_a = s1.extract(3); // !empty = !empty
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+  node_b = s2.extract(0); // empty = empty
+  VERIFY( node_b.empty() );
+  node_b = s2.extract(6); // empty = !empty
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(!empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.get_allocator() == s1.get_allocator() );
+
+  node_a = {};
+  node_b = std::move(node_a); // !empty = empty
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+}
+
+void
+test_alloc_lifetime()
+{
+  Alloc<int> a(1);
+  test_type s({1,2,3}, a);
+  VERIFY( a.id.use_count() == 2 ); // a and the copy in s
+
+  s.insert(s.extract(1));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(s.begin(), s.extract(2));
+  VERIFY( a.id.use_count() == 2 );
+
+  auto node = s.extract(1);
+  VERIFY( a.id.use_count() == 3 );
+  node = s.extract(0);
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(std::move(node));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type(s));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type({4,5,6}, a));
+  VERIFY( a.id.use_count() == 2 );
+}
+
+int main()
+{
+  test_node_ops();
+  test_alloc_lifetime();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/set/modifiers/114401.cc b/libstdc++-v3/testsuite/23_containers/set/modifiers/114401.cc
new file mode 100644
index 00000000000..f0a06a8c1a2
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/set/modifiers/114401.cc
@@ -0,0 +1,125 @@
+// { dg-do run { target c++17 } }
+
+// PR libstdc++/114401 allocator destructor omitted when reinserting node_handle
+
+#include <set>
+#include <memory>
+#include <testsuite_hooks.h>
+
+template<typename T>
+struct Alloc
+{
+  using value_type = T;
+  using propagate_on_container_copy_assignment = std::true_type;
+  using propagate_on_container_move_assignment = std::true_type;
+  using propagate_on_container_swap = std::true_type;
+
+  Alloc(int identity) : id(std::make_shared<int>(identity)) { }
+
+  template<typename U>
+    Alloc(const Alloc<U> a) : id(a.id) { }
+
+  T* allocate(std::size_t n) { return std::allocator<T>().allocate(n); }
+  void deallocate(T* p, std::size_t n) { std::allocator<T>().deallocate(p, n); }
+
+  template<typename U>
+    friend bool
+    operator==(const Alloc& a, const Alloc<U>& a2)
+    { return a.id == a2.id; }
+
+  template<typename U>
+    friend bool
+    operator!=(const Alloc& a, const Alloc<U>& a2)
+    { return !(a == a2); }
+
+  std::shared_ptr<int> id;
+};
+
+using test_type = std::set<int, std::less<int>, Alloc<int>>;
+
+void
+test_node_ops()
+{
+  test_type s1({1,3,5}, Alloc<int>(1));
+  test_type s2({2,4,6,8}, Alloc<int>(2));
+  VERIFY( s1.get_allocator() != s2.get_allocator() );
+
+  auto node_a = s1.extract(1);
+  VERIFY( ! node_a.empty() );
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+
+  node_a = std::move(node_a); // self-move
+  VERIFY( node_a.empty() );
+
+  swap(node_a, node_a); // self-swap
+  VERIFY( node_a.empty() );
+
+  auto node_b = s2.extract(2);
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  node_a = std::move(node_b); // empty = !empty
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(!empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  node_a = s1.extract(3); // !empty = !empty
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+  node_b = s2.extract(0); // empty = empty
+  VERIFY( node_b.empty() );
+  node_b = s2.extract(6); // empty = !empty
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(!empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.get_allocator() == s1.get_allocator() );
+
+  node_a = {};
+  node_b = std::move(node_a); // !empty = empty
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+}
+
+void
+test_alloc_lifetime()
+{
+  Alloc<int> a(1);
+  test_type s({1,2,3}, a);
+  VERIFY( a.id.use_count() == 2 ); // a and the copy in s
+
+  s.insert(s.extract(1));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(s.begin(), s.extract(2));
+  VERIFY( a.id.use_count() == 2 );
+
+  auto node = s.extract(1);
+  VERIFY( a.id.use_count() == 3 );
+  node = s.extract(0);
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(std::move(node));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type(s));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type({4,5,6}, a));
+  VERIFY( a.id.use_count() == 2 );
+}
+
+int main()
+{
+  test_node_ops();
+  test_alloc_lifetime();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_multiset/modifiers/114401.cc b/libstdc++-v3/testsuite/23_containers/unordered_multiset/modifiers/114401.cc
new file mode 100644
index 00000000000..0a6ea77bf31
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_multiset/modifiers/114401.cc
@@ -0,0 +1,126 @@
+// { dg-do run { target c++17 } }
+
+// PR libstdc++/114401 allocator destructor omitted when reinserting node_handle
+
+#include <unordered_set>
+#include <memory>
+#include <testsuite_hooks.h>
+
+template<typename T>
+struct Alloc
+{
+  using value_type = T;
+  using propagate_on_container_copy_assignment = std::true_type;
+  using propagate_on_container_move_assignment = std::true_type;
+  using propagate_on_container_swap = std::true_type;
+
+  Alloc(int identity) : id(std::make_shared<int>(identity)) { }
+
+  template<typename U>
+    Alloc(const Alloc<U> a) : id(a.id) { }
+
+  T* allocate(std::size_t n) { return std::allocator<T>().allocate(n); }
+  void deallocate(T* p, std::size_t n) { std::allocator<T>().deallocate(p, n); }
+
+  template<typename U>
+    friend bool
+    operator==(const Alloc& a, const Alloc<U>& a2)
+    { return a.id == a2.id; }
+
+  template<typename U>
+    friend bool
+    operator!=(const Alloc& a, const Alloc<U>& a2)
+    { return !(a == a2); }
+
+  std::shared_ptr<int> id;
+};
+
+using test_type
+  = std::unordered_multiset<int, std::hash<int>, std::equal_to<int>, Alloc<int>>;
+
+void
+test_node_ops()
+{
+  test_type s1({1,3,5}, 3, Alloc<int>(1));
+  test_type s2({2,4,6,8}, 4, Alloc<int>(2));
+  VERIFY( s1.get_allocator() != s2.get_allocator() );
+
+  auto node_a = s1.extract(1);
+  VERIFY( ! node_a.empty() );
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+
+  node_a = std::move(node_a); // self-move
+  VERIFY( node_a.empty() );
+
+  swap(node_a, node_a); // self-swap
+  VERIFY( node_a.empty() );
+
+  auto node_b = s2.extract(2);
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  node_a = std::move(node_b); // empty = !empty
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(!empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  node_a = s1.extract(3); // !empty = !empty
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+  node_b = s2.extract(0); // empty = empty
+  VERIFY( node_b.empty() );
+  node_b = s2.extract(6); // empty = !empty
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(!empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.get_allocator() == s1.get_allocator() );
+
+  node_a = {};
+  node_b = std::move(node_a); // !empty = empty
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+}
+
+void
+test_alloc_lifetime()
+{
+  Alloc<int> a(1);
+  test_type s({1,2,3}, 3, a);
+  VERIFY( a.id.use_count() == 2 ); // a and the copy in s
+
+  s.insert(s.extract(1));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(s.begin(), s.extract(2));
+  VERIFY( a.id.use_count() == 2 );
+
+  auto node = s.extract(1);
+  VERIFY( a.id.use_count() == 3 );
+  node = s.extract(0);
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(std::move(node));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type(s));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type({4,5,6}, 3, a));
+  VERIFY( a.id.use_count() == 2 );
+}
+
+int main()
+{
+  test_node_ops();
+  test_alloc_lifetime();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_set/modifiers/114401.cc b/libstdc++-v3/testsuite/23_containers/unordered_set/modifiers/114401.cc
new file mode 100644
index 00000000000..3ae2f2d5b5c
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_set/modifiers/114401.cc
@@ -0,0 +1,126 @@
+// { dg-do run { target c++17 } }
+
+// PR libstdc++/114401 allocator destructor omitted when reinserting node_handle
+
+#include <unordered_set>
+#include <memory>
+#include <testsuite_hooks.h>
+
+template<typename T>
+struct Alloc
+{
+  using value_type = T;
+  using propagate_on_container_copy_assignment = std::true_type;
+  using propagate_on_container_move_assignment = std::true_type;
+  using propagate_on_container_swap = std::true_type;
+
+  Alloc(int identity) : id(std::make_shared<int>(identity)) { }
+
+  template<typename U>
+    Alloc(const Alloc<U> a) : id(a.id) { }
+
+  T* allocate(std::size_t n) { return std::allocator<T>().allocate(n); }
+  void deallocate(T* p, std::size_t n) { std::allocator<T>().deallocate(p, n); }
+
+  template<typename U>
+    friend bool
+    operator==(const Alloc& a, const Alloc<U>& a2)
+    { return a.id == a2.id; }
+
+  template<typename U>
+    friend bool
+    operator!=(const Alloc& a, const Alloc<U>& a2)
+    { return !(a == a2); }
+
+  std::shared_ptr<int> id;
+};
+
+using test_type
+  = std::unordered_set<int, std::hash<int>, std::equal_to<int>, Alloc<int>>;
+
+void
+test_node_ops()
+{
+  test_type s1({1,3,5}, 3, Alloc<int>(1));
+  test_type s2({2,4,6,8}, 4, Alloc<int>(2));
+  VERIFY( s1.get_allocator() != s2.get_allocator() );
+
+  auto node_a = s1.extract(1);
+  VERIFY( ! node_a.empty() );
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+
+  node_a = std::move(node_a); // self-move
+  VERIFY( node_a.empty() );
+
+  swap(node_a, node_a); // self-swap
+  VERIFY( node_a.empty() );
+
+  auto node_b = s2.extract(2);
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  node_a = std::move(node_b); // empty = !empty
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(!empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.empty() );
+
+  node_a = s1.extract(3); // !empty = !empty
+  VERIFY( node_a.get_allocator() == s1.get_allocator() );
+  node_b = s2.extract(0); // empty = empty
+  VERIFY( node_b.empty() );
+  node_b = s2.extract(6); // empty = !empty
+  VERIFY( node_b.get_allocator() == s2.get_allocator() );
+
+  swap(node_a, node_b); // swap(!empty, !empty)
+  VERIFY( node_a.get_allocator() == s2.get_allocator() );
+  VERIFY( node_b.get_allocator() == s1.get_allocator() );
+
+  node_a = {};
+  node_b = std::move(node_a); // !empty = empty
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+
+  swap(node_a, node_b); // swap(empty, empty)
+  VERIFY( node_a.empty() );
+  VERIFY( node_b.empty() );
+}
+
+void
+test_alloc_lifetime()
+{
+  Alloc<int> a(1);
+  test_type s({1,2,3}, 3, a);
+  VERIFY( a.id.use_count() == 2 ); // a and the copy in s
+
+  s.insert(s.extract(1));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(s.begin(), s.extract(2));
+  VERIFY( a.id.use_count() == 2 );
+
+  auto node = s.extract(1);
+  VERIFY( a.id.use_count() == 3 );
+  node = s.extract(0);
+  VERIFY( a.id.use_count() == 2 );
+
+  s.insert(std::move(node));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type(s));
+  VERIFY( a.id.use_count() == 2 );
+
+  s.merge(test_type({4,5,6}, 3, a));
+  VERIFY( a.id.use_count() == 2 );
+}
+
+int main()
+{
+  test_node_ops();
+  test_alloc_lifetime();
+}

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2024-04-03 10:46 [gcc r13-8570] libstdc++: Destroy allocators in re-inserted container nodes [PR114401] Jonathan Wakely

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