missing implementation: casting const std::unique_ptr<T>&

This causes, for example, make_iterator to fail.

Author: rhaschke

tests/test_sequences_and_iterators.cpp

@@ -355,4 +355,5 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
     static std::vector<int> list = { 1, 2, 3 };
     m.def("make_iterator_1", []() { return py::make_iterator<py::return_value_policy::copy>(list); });
     m.def("make_iterator_2", []() { return py::make_iterator<py::return_value_policy::automatic>(list); });
+
 }

tests/test_smart_ptr.cpp

@@ -462,4 +462,25 @@ TEST_SUBMODULE(smart_ptr, m) {
                 list.append(py::cast(e));
             return list;
         });
+
+    // list of std::unique_ptr<T>
+    struct IntType {
+        IntType(int value) : value(value) {}
+        int value;
+    };
+    using IntTypeHolder = std::unique_ptr<IntType>;
+    struct IntTypeList : std::list<IntTypeHolder> {
+        const IntTypeHolder& front() const { return std::list<IntTypeHolder>::front(); }
+    };
+    py::class_<IntType>(m, "IntType").def(py::init<int>()).def_readwrite("value", &IntType::value);
+    py::class_<IntTypeList>(m, "IntTypeList")
+        .def("front", &IntTypeList::front, py::return_value_policy::reference_internal)
+        .def("__iter__", [](IntTypeList &c) { return py::make_iterator(c.begin(), c.end()); },
+             py::keep_alive<0, 1>());
+    m.def("make_int_type_list", [](py::object o) {
+        IntTypeList l;
+        for (auto item : o)
+            l.emplace_back(IntTypeHolder(new IntType(py::cast<int>(item))));
+        return l;
+    });
 }

tests/test_smart_ptr.py

@@ -316,3 +316,9 @@ def test_shared_ptr_gc():
     pytest.gc_collect()
     for i, v in enumerate(el.get()):
         assert i == v.value()
+
+
+def test_iterator_for_list_of_holders():
+    lst = m.make_int_type_list([1, 2, 3])
+    assert lst.front().value == 1
+    assert [obj.value for obj in lst] == [1, 2, 3]