Use std::addressof to obtain holder address instead of operator&

include/pybind11/cast.h

@@ -1392,7 +1392,7 @@ public:
 
     explicit operator type*() { return this->value; }
     explicit operator type&() { return *(this->value); }
-    explicit operator holder_type*() { return &holder; }
+    explicit operator holder_type*() { return std::addressof(holder); }
 
     // Workaround for Intel compiler bug
     // see pybind11 issue 94
@@ -1462,7 +1462,7 @@ struct move_only_holder_caster {
 
     static handle cast(holder_type &&src, return_value_policy, handle) {
         auto *ptr = holder_helper<holder_type>::get(src);
-        return type_caster_base<type>::cast_holder(ptr, &src);
+        return type_caster_base<type>::cast_holder(ptr, std::addressof(src));
     }
     static PYBIND11_DESCR name() { return type_caster_base<type>::name(); }
 };

include/pybind11/pybind11.h

@@ -1267,25 +1267,25 @@ private:
             auto sh = std::dynamic_pointer_cast<typename holder_type::element_type>(
                     v_h.value_ptr<type>()->shared_from_this());
             if (sh) {
-                new (&v_h.holder<holder_type>()) holder_type(std::move(sh));
+                new (std::addressof(v_h.holder<holder_type>())) holder_type(std::move(sh));
                 v_h.set_holder_constructed();
             }
         } catch (const std::bad_weak_ptr &) {}
 
         if (!v_h.holder_constructed() && inst->owned) {
-            new (&v_h.holder<holder_type>()) holder_type(v_h.value_ptr<type>());
+            new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
             v_h.set_holder_constructed();
         }
     }
 
     static void init_holder_from_existing(const detail::value_and_holder &v_h,
             const holder_type *holder_ptr, std::true_type /*is_copy_constructible*/) {
-        new (&v_h.holder<holder_type>()) holder_type(*reinterpret_cast<const holder_type *>(holder_ptr));
+        new (std::addressof(v_h.holder<holder_type>())) holder_type(*reinterpret_cast<const holder_type *>(holder_ptr));
     }
 
     static void init_holder_from_existing(const detail::value_and_holder &v_h,
             const holder_type *holder_ptr, std::false_type /*is_copy_constructible*/) {
-        new (&v_h.holder<holder_type>()) holder_type(std::move(*const_cast<holder_type *>(holder_ptr)));
+        new (std::addressof(v_h.holder<holder_type>())) holder_type(std::move(*const_cast<holder_type *>(holder_ptr)));
     }
 
     /// Initialize holder object, variant 2: try to construct from existing holder object, if possible
@@ -1295,7 +1295,7 @@ private:
             init_holder_from_existing(v_h, holder_ptr, std::is_copy_constructible<holder_type>());
             v_h.set_holder_constructed();
         } else if (inst->owned || detail::always_construct_holder<holder_type>::value) {
-            new (&v_h.holder<holder_type>()) holder_type(v_h.value_ptr<type>());
+            new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
             v_h.set_holder_constructed();
         }
     }

tests/test_smart_ptr.cpp

@@ -55,6 +55,35 @@ public:
 };
 PYBIND11_DECLARE_HOLDER_TYPE(T, custom_unique_ptr<T>);
 
+// Simple custom holder that works like shared_ptr and has operator& overload
+// To obtain address of an instance of this holder pybind should use std::addressof
+// Attempt to get address via operator& may leads to segmentation fault
+template <typename T>
+class shared_ptr_with_addressof_operator {
+    std::shared_ptr<T> impl;
+public:
+    shared_ptr_with_addressof_operator( ) = default;
+    shared_ptr_with_addressof_operator(T* p) : impl(p) { }
+    T* get() const { return impl.get(); }
+    T** operator&() { throw std::logic_error("Call of overloaded operator& is not expected"); }
+};
+PYBIND11_DECLARE_HOLDER_TYPE(T, shared_ptr_with_addressof_operator<T>);
+
+// Simple custom holder that works like unique_ptr and has operator& overload
+// To obtain address of an instance of this holder pybind should use std::addressof
+// Attempt to get address via operator& may leads to segmentation fault
+template <typename T>
+class unique_ptr_with_addressof_operator {
+    std::unique_ptr<T> impl;
+public:
+    unique_ptr_with_addressof_operator() = default;
+    unique_ptr_with_addressof_operator(T* p) : impl(p) { }
+    T* get() const { return impl.get(); }
+    T* release_ptr() { return impl.release(); }
+    T** operator&() { throw std::logic_error("Call of overloaded operator& is not expected"); }
+};
+PYBIND11_DECLARE_HOLDER_TYPE(T, unique_ptr_with_addressof_operator<T>);
+
 
 TEST_SUBMODULE(smart_ptr, m) {
 
@@ -234,6 +263,41 @@ TEST_SUBMODULE(smart_ptr, m) {
     py::class_<C, custom_unique_ptr<C>>(m, "TypeWithMoveOnlyHolder")
         .def_static("make", []() { return custom_unique_ptr<C>(new C); });
 
+    // test_holder_with_addressof_operator
+    struct TypeForHolderWithAddressOf {
+        TypeForHolderWithAddressOf() { print_created(this); }
+        TypeForHolderWithAddressOf(const TypeForHolderWithAddressOf &) { print_copy_created(this); }
+        TypeForHolderWithAddressOf(TypeForHolderWithAddressOf &&) { print_move_created(this); }
+        ~TypeForHolderWithAddressOf() { print_destroyed(this); }
+        std::string toString() const {
+            return "TypeForHolderWithAddressOf[" + std::to_string(value) + "]";
+        }
+        int value = 42;
+    };
+    using HolderWithAddressOf = shared_ptr_with_addressof_operator<TypeForHolderWithAddressOf>;
+    py::class_<TypeForHolderWithAddressOf, HolderWithAddressOf>(m, "TypeForHolderWithAddressOf")
+        .def_static("make", []() { return HolderWithAddressOf(new TypeForHolderWithAddressOf); })
+        .def("get", [](const HolderWithAddressOf &self) { return self.get(); })
+        .def("print_object_1", [](const TypeForHolderWithAddressOf *obj) { py::print(obj->toString()); })
+        .def("print_object_2", [](HolderWithAddressOf obj) { py::print(obj.get()->toString()); })
+        .def("print_object_3", [](const HolderWithAddressOf &obj) { py::print(obj.get()->toString()); })
+        .def("print_object_4", [](const HolderWithAddressOf *obj) { py::print((*obj).get()->toString()); });
+
+    // test_move_only_holder_with_addressof_operator
+    struct TypeForMoveOnlyHolderWithAddressOf {
+        TypeForMoveOnlyHolderWithAddressOf(int value) : value{value} { print_created(this); }
+        ~TypeForMoveOnlyHolderWithAddressOf() { print_destroyed(this); }
+        std::string toString() const {
+            return "MoveOnlyHolderWithAddressOf[" + std::to_string(value) + "]";
+        }
+        int value;
+    };
+    using MoveOnlyHolderWithAddressOf = unique_ptr_with_addressof_operator<TypeForMoveOnlyHolderWithAddressOf>;
+    py::class_<TypeForMoveOnlyHolderWithAddressOf, MoveOnlyHolderWithAddressOf>(m, "TypeForMoveOnlyHolderWithAddressOf")
+        .def_static("make", []() { return MoveOnlyHolderWithAddressOf(new TypeForMoveOnlyHolderWithAddressOf(0)); })
+        .def_readwrite("value", &TypeForMoveOnlyHolderWithAddressOf::value)
+        .def("print_object", [](const TypeForMoveOnlyHolderWithAddressOf *obj) { py::print(obj->toString()); });
+
     // test_smart_ptr_from_default
     struct HeldByDefaultHolder { };
     py::class_<HeldByDefaultHolder>(m, "HeldByDefaultHolder")

tests/test_smart_ptr.py

@@ -203,6 +203,50 @@ def test_move_only_holder():
     assert stats.alive() == 0
 
 
+def test_holder_with_addressof_operator():
+    # this test must not throw exception from c++
+    a = m.TypeForHolderWithAddressOf.make()
+    a.print_object_1()
+    a.print_object_2()
+    a.print_object_3()
+    a.print_object_4()
+
+    stats = ConstructorStats.get(m.TypeForHolderWithAddressOf)
+    assert stats.alive() == 1
+
+    np = m.TypeForHolderWithAddressOf.make()
+    assert stats.alive() == 2
+    del a
+    assert stats.alive() == 1
+    del np
+    assert stats.alive() == 0
+
+    b = m.TypeForHolderWithAddressOf.make()
+    c = b
+    assert b.get() is c.get()
+    assert stats.alive() == 1
+
+    del b
+    assert stats.alive() == 1
+
+    del c
+    assert stats.alive() == 0
+
+
+def test_move_only_holder_with_addressof_operator():
+    a = m.TypeForMoveOnlyHolderWithAddressOf.make()
+    a.print_object()
+
+    stats = ConstructorStats.get(m.TypeForMoveOnlyHolderWithAddressOf)
+    assert stats.alive() == 1
+
+    a.value = 42
+    assert a.value == 42
+
+    del a
+    assert stats.alive() == 0
+
+
 def test_smart_ptr_from_default():
     instance = m.HeldByDefaultHolder()
     with pytest.raises(RuntimeError) as excinfo: