Test PR. See details.

This test defines a virtual class and its trampoline class and a simple struct
that is used to pass the instance of this class around as shared_ptr.

When passed in the container struct the connection to the dervived class is lost
and calling the virtual method throws: RuntimeError: Tried to call pure virtual
function "VirtualItem::get".

Author: ManuelSchneid3r

tests/test_class_sh_virtual_py_cpp_mix.cpp

@@ -29,6 +29,34 @@ int get_from_cpp_plainc_ptr(const Base *b) { return b->get() + 4000; }
 
 int get_from_cpp_unique_ptr(std::unique_ptr<Base> b) { return b->get() + 5000; }
 
+
+// >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+struct VirtualItem
+{
+    VirtualItem() = default;
+    virtual ~VirtualItem() = default;
+    virtual int get() const = 0;
+};
+
+struct VirtualItemTrampoline : public VirtualItem, py::trampoline_self_life_support
+{
+    int get() const override { PYBIND11_OVERRIDE_PURE(int, VirtualItem, get, ); }
+};
+
+struct VirtualItemContainer
+{
+    std::shared_ptr<VirtualItem> held;
+    // ...
+};
+
+void cpp_space_test(std::shared_ptr<VirtualItemContainer> container_vec)
+{
+    auto i = container_vec->held->get();  // segfaults
+}
+
+// <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+
 struct BaseVirtualOverrider : Base, py::trampoline_self_life_support {
     using Base::Base;
 
@@ -55,4 +83,19 @@ TEST_SUBMODULE(class_sh_virtual_py_cpp_mix, m) {
 
     m.def("get_from_cpp_plainc_ptr", get_from_cpp_plainc_ptr, py::arg("b"));
     m.def("get_from_cpp_unique_ptr", get_from_cpp_unique_ptr, py::arg("b"));
+
+    // >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+    py::classh<VirtualItem, VirtualItemTrampoline>(m, "VirtualItem")
+        .def(py::init<>())
+        .def("get", &VirtualItem::get)
+        ;
+
+    py::classh<VirtualItemContainer>(m, "VirtualItemContainer")
+        .def(py::init<std::shared_ptr<VirtualItem>>())
+        ;
+
+    m.def("cpp_space_test", cpp_space_test);
+
+    // <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
 }

tests/test_class_sh_virtual_py_cpp_mix.py

@@ -64,3 +64,14 @@ def test_get_from_cpp_plainc_ptr(ctor, expected):
 def test_get_from_cpp_unique_ptr(ctor, expected):
     obj = ctor()
     assert m.get_from_cpp_unique_ptr(obj) == expected
+
+#  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+
+class VirtualItemDerived(m.VirtualItem):
+    def getInt(self):
+        return 42
+
+def test_cpp_space_test():
+    m.cpp_space_test(m.VirtualItemContainer(VirtualItemDerived()))
+
+#  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<