[BUG]: 3.0.2 is crashing when binding with std containers

[hiphyengine]

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What version (or hash if on master) of pybind11 are you using?

3.0.2

Problem description

I updated from 3.0.1 to 3.0.2 and now pybind11 is crashing when the compiled and loaded in Python. I am currently trying it in windows with VS2026 and intel oneAPI compiler. I haven't tried Linux or g++ yet. I also have not narrowed down which container binding is crashing.
version 3.0.1 is working fine. I have attached the crash report. It is coming from Blender. Blender is using python 3.11. The crash is from python.

blender.crash.txt

Reproducible example code

C++

#include <pybind11/pybind11.h>
namespace py = pybind11;

PYBIND11_MAKE_OPAQUE(std::array<double, 3>)
PYBIND11_MAKE_OPAQUE(std::array<int, 3>)
PYBIND11_MAKE_OPAQUE(std::vector<double>)
PYBIND11_MAKE_OPAQUE(std::vector<int>)
PYBIND11_MAKE_OPAQUE(std::vector<uint8_t>)
PYBIND11_MAKE_OPAQUE(std::vector<std::array<double, 3>>)
PYBIND11_MAKE_OPAQUE(std::vector<std::array<int, 3>>)
PYBIND11_MAKE_OPAQUE(std::vector<std::string>)

PYBIND11_MODULE(TestAPI, m, py::mod_gil_not_used())
{
}

Python:

if (os.name == "nt"):
    try:
        ctypes.CDLL(os.path.join(addon_dir, "cAPI\SimulationAPI.cp311-win_amd64.pyd"))
    except OSError as e:
        print(f"Error loading .pyd file: {e}")

from .cAPI import TestAPI

Is this a regression? Put the last known working version here if it is.

3.0.1

[ethanglaser]

Potentially related: when bumping pybind11 3.0.1 -> 3.0.2 in scikit-learn-intelex (uxlfoundation/scikit-learn-intelex#2993) we also get crashes (unfortunately the logs are not verbose and it's windows-specific so I don't have a great reproducer: https://github.com/uxlfoundation/scikit-learn-intelex/actions/runs/22852255330/job/66283425399?pr=2993#step:14:2759)

This is happening specifically with our python 3.10 + sklearn 1.0 validation step, and scikit-learn-intelex is also part of the oneAPI ecosystem

[rwgk]

@hiphyengine @ethanglaser Could you please try again with the master branch? I don't think that #6018 fixed the issue, but hopefully you'll see more meaningful error messages.

[hiphyengine]

Hi, I am trying to test it on Windows, however, Pybind11 uses boost_1_56 that has no boostconfig.cmake files, and my cmake is can't find the boost path even when i provided the boost root directory. Is there a document for me to follow on how to build Pybind11 on windows?

[rwgk]

Pybind11 uses boost_1_56

I just looked through the pybind11 production code (under include/pybind11) to be certain: the pybind11 production code has no boost dependency. Only two of our unit tests do.

I was hoping you'd simply drop in the pybind11 master branch for what you were using before, everything else unchanged. E.g. you could rename include/pybind11 to something else, then copy include/pybind11 from master there.

[ethanglaser]

Interestingly no failures with main branch installed: https://github.com/uxlfoundation/scikit-learn-intelex/actions/runs/23752185706/job/69197057100?pr=2993
Let me try to rerun with the 3.0.2 update

[ethanglaser]

Looks like I no longer have an issue with the 3.0.2 package: https://github.com/uxlfoundation/scikit-learn-intelex/actions/runs/23753993090/job/69203639472?pr=2993. Not sure what led to the issue in the first place, as there were fails clearly linked to the pybind11 version that we did not see elsewhere.