Add test_python_multiple_inheritance (Not For Merging)

tests/CMakeLists.txt

@@ -33,6 +33,7 @@ nanobind_add_module(test_ndarray_ext test_ndarray.cpp ${NB_EXTRA_ARGS})
 nanobind_add_module(test_intrusive_ext test_intrusive.cpp object.cpp object.h ${NB_EXTRA_ARGS})
 nanobind_add_module(test_exception_ext test_exception.cpp ${NB_EXTRA_ARGS})
 nanobind_add_module(test_make_iterator_ext test_make_iterator.cpp ${NB_EXTRA_ARGS})
+nanobind_add_module(test_python_multiple_inheritance_ext test_python_multiple_inheritance.cpp ${NB_EXTRA_ARGS})
 
 find_package (Eigen3 3.3.1 NO_MODULE)
 if (TARGET Eigen3::Eigen)
@@ -67,6 +68,7 @@ set(TEST_FILES
   test_inter_module.py
   test_intrusive.py
   test_make_iterator.py
+  test_python_multiple_inheritance.py
   test_stl.py
   test_stl_bind_map.py
   test_stl_bind_vector.py

tests/test_python_multiple_inheritance.cpp

@@ -0,0 +1,46 @@
+#include <nanobind/nanobind.h>
+
+namespace test_python_multiple_inheritance {
+
+// Copied from:
+// https://github.com/google/clif/blob/5718e4d0807fd3b6a8187dde140069120b81ecef/clif/testing/python_multiple_inheritance.h
+
+struct CppBase {
+    explicit CppBase(int value) : base_value(value) {}
+    int get_base_value() const { return base_value; }
+    void reset_base_value(int new_value) { base_value = new_value; }
+
+private:
+    int base_value;
+};
+
+struct CppDrvd : CppBase {
+    explicit CppDrvd(int value) : CppBase(value), drvd_value(value * 3) {}
+    int get_drvd_value() const { return drvd_value; }
+    void reset_drvd_value(int new_value) { drvd_value = new_value; }
+
+    int get_base_value_from_drvd() const { return get_base_value(); }
+    void reset_base_value_from_drvd(int new_value) { reset_base_value(new_value); }
+
+private:
+    int drvd_value;
+};
+
+} // namespace test_python_multiple_inheritance
+
+NB_MODULE(test_python_multiple_inheritance_ext, m) {
+    using namespace test_python_multiple_inheritance;
+    namespace nb = nanobind;
+
+    nb::class_<CppBase>(m, "CppBase")
+        .def(nb::init<int>())
+        .def("get_base_value", &CppBase::get_base_value)
+        .def("reset_base_value", &CppBase::reset_base_value);
+
+    nb::class_<CppDrvd, CppBase>(m, "CppDrvd")
+        .def(nb::init<int>())
+        .def("get_drvd_value", &CppDrvd::get_drvd_value)
+        .def("reset_drvd_value", &CppDrvd::reset_drvd_value)
+        .def("get_base_value_from_drvd", &CppDrvd::get_base_value_from_drvd)
+        .def("reset_base_value_from_drvd", &CppDrvd::reset_base_value_from_drvd);
+}

tests/test_python_multiple_inheritance.py

@@ -0,0 +1,22 @@
+# Adapted from:
+# https://github.com/google/clif/blob/5718e4d0807fd3b6a8187dde140069120b81ecef/clif/testing/python/python_multiple_inheritance_test.py
+# See also:
+# https://github.com/pybind/pybind11/pull/4762
+
+import test_python_multiple_inheritance_ext as m
+
+
+class PC(m.CppBase):
+    pass
+
+
+# RuntimeError: nb_type_init(): invalid number of bases!
+# class PPCC(PC, m.CppDrvd):
+#     pass
+
+
+def test_PC():
+    d = PC(11)
+    assert d.get_base_value() == 11
+    d.reset_base_value(13)
+    assert d.get_base_value() == 13