segmentation fault when shared library callback

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Problem description

Hi,
I have a C++ shared library with .so and inculde files, these include files define callback class and virtual function:

struct MyData
{
    char msg[10];
};

class Spi
{
public:
    virtual void OnData(MyData* data) {}
};

I define a trampoline class PySpi , and bind the spi class and the MyData
struct

class PySpi : public Spi {
public:
    using Spi::Spi;

    void OnData(MyData* data) override {
        PYBIND11_OVERRIDE(void, Spi, OnData, data);
    }
};

    py::class_<MyData>(m, "MyData")
        .def(py::init<>())
        .def_property("msg", 
            py::cpp_function([](MyData &self) {return self.msg;}, py::return_value_policy::copy),
            py::cpp_function([](MyData &self, std::string &a) {std::strcpy(self.msg, a.c_str());})
        );

    py::class_<Spi, PySpi>(m, "Spi")
        .def(py::init<>())
        .def("OnData", &Spi::OnData);

overriding virtual function in Python:

class MySpi(Spi):
    def __init__(self):
        Spi.__init__(self)
    def OnData(self, data):
        print("[OnData]")

I am getting a segmentation fault when shared library callback OnData. I tried to change struct return_value_policy, but it didn't work, Am I simply need some policies config of binding?

Reproducible example code

No response

No repository file or test is named. Start by reproducing the shared-library callback with the C++ trampoline and Python subclass shown in the issue, then trace the OnData binding and callback path. Done means the segmentation fault is reproduced, its cause is identified, and a verified fix or clear diagnosis is documented.