[BUG]: Overriding the pure virtual function result in trace trap error

[umarfarook882]

Problem description

Overriding the pure virtual function in class result in trace trap error in python 3.12

Python: 3.12
nanobind: 2.1.0

Reproducible example code

#include <iostream>
#include <nanobind/nanobind.h>
#include <nanobind/stl/string.h>
#include <nanobind/trampoline.h>

class Base {
public:
    std::string name;
    Base(const std::string &name) : name(name) { 
        std::cout << "Base constructor" << std::endl;
    }
    virtual std::string bark() = 0;
};

class PyBase : public Base {
public:
    PyBase(const std::string &s) : Base(s) {
        std::cout << "PyBase constructor" << std::endl;
    }
    NB_TRAMPOLINE(Base, 1);

    std::string bark()  override {
        NB_OVERRIDE_PURE(bark);
    }
};

void alarm1(Base *base, size_t count = 3) {
    for (size_t i = 0; i < count; ++i)
        std::cout << base->bark() << std::endl;
}

NB_MODULE(my_ext, m)
{
    m.attr("__version__") = "0.0.1"; 
    nb::class_<Base, PyBase>(m, "Base")
        .def(nb::init<const std::string &>())
        .def("bark", &Base::bark); 
    m.def("alarm1", &alarm1, "base"_a, "count"_a = 3);
}

[wjakob]

I have doubts that there is a bug here, as the ability to override virtual calls (or not) is already tested on Python 3.12 by the CI test suite.

Your reproducer is missing the Python part.

What I suspect might be happening is that you overrode __init__ and did not call super().__init__().

[wjakob]

Closing due to a lack of response. Feel free to post here if there is more information, and I will reopen the PR.