Moving several tests to github.com/rwgk/rwgk_tbx/tree/main/pybind11_tests

https://github.com/rwgk/rwgk_tbx/commit/a2c2f88174a30f5de80d7d26e0f77c7b60f5fb85

These tests are from experimenting, and for demonstrating UB in pybind11 multiple inheritance handling ("first_base"), to be fixed later.

tests/test_cpp_base_py_derived.cpp

-// pybind11 equivalent of Boost.Python test:
-// https://github.com/rwgk/rwgk_tbx/blob/6c9a6d6bc72d5c1b8609724433259c5b47178680/cpp_base_py_derived_ext.cpp
-// See also: https://github.com/pybind/pybind11/issues/1333 (this was the starting point)
-
-#include "pybind11_tests.h"
-
-namespace pybind11_tests {
-namespace cpp_base_py_derived {
-
-struct base {
-  base() : base_num(100) {}
-
-  virtual int get_num() const { return base_num; }
-
-  virtual std::shared_ptr<base> clone() const {
-    return std::shared_ptr<base>(new base(150));
-  }
-
-  virtual ~base() = default;
-
- private:
-  explicit base(int num) : base_num(num) {}
-  int base_num;
-};
-
-inline int get_num(std::shared_ptr<base> b) { return b->get_num(); }
-
-inline int clone_get_num(std::shared_ptr<base> b) {
-  std::shared_ptr<base> c = b->clone();
-  return (b->get_num() + 3) * 1000 + (c->get_num() + 7);
-}
-
-struct base_trampoline : public base {
-  using base::base;
-
-  int get_num() const override {
-    PYBIND11_OVERRIDE(int, base, get_num);
-  }
-
-  std::shared_ptr<base> clone() const override {
-    PYBIND11_OVERRIDE(std::shared_ptr<base>, base, clone);
-  }
-};
-
-TEST_SUBMODULE(cpp_base_py_derived, m) {
-  py::class_<base, base_trampoline, std::shared_ptr<base>>(m, "base")
-    .def(py::init<>())
-    .def("get_num", &base::get_num)
-    .def("clone", &base::clone)
-  ;
-
-  m.def("get_num", get_num);
-  m.def("clone_get_num", clone_get_num);
-}
-
-}  // namespace cpp_base_py_derived
-}  // namespace pybind11_tests

tests/test_cpp_base_py_derived.py

-# -*- coding: utf-8 -*-
-# pybind11 equivalent of Boost.Python test:
-# https://github.com/rwgk/rwgk_tbx/blob/6c9a6d6bc72d5c1b8609724433259c5b47178680/tst_cpp_base_py_derived.py
-# See also: https://github.com/pybind/pybind11/issues/1333 (this was the starting point)
-
-from pybind11_tests import cpp_base_py_derived as m
-
-
-class drvd(m.base):  # noqa: N801
-    def __init__(self, _num=200):
-        super().__init__()
-        self._drvd_num = _num
-
-    def get_num(self):
-        return self._drvd_num
-
-    def clone(self):
-        return drvd(250)
-
-
-def test_base():
-    b = m.base()
-    assert b.get_num() == 100
-    assert m.get_num(b) == 100
-    bc = b.clone()
-    assert bc.get_num() == 150
-    assert m.clone_get_num(b) == 103157
-
-
-def test_drvd():
-    d = drvd()
-    assert d.get_num() == 200
-    assert m.get_num(d) == 200
-    dc = d.clone()
-    assert dc.get_num() == 250
-    assert m.clone_get_num(d) == 203257

tests/test_holder_shared_ptr.cpp

-// KEEP IN SYNC WITH test_holder_unique_ptr.cpp
-
-#include "pybind11_tests.h"
-
-#include <iostream>
-#include <memory>
-
-namespace pybind11_tests {
-namespace holder_shared_ptr {
-
-inline void to_cout(std::string text) { std::cout << text << std::endl; }
-
-class pointee { // NOT copyable.
-  public:
-    pointee() { to_cout("pointee::pointee()"); }
-
-    int get_int() const {
-        to_cout("pointee::get_int()");
-        return 213;
-    }
-
-    ~pointee() { to_cout("~pointee()"); }
-
-  private:
-    pointee(const pointee &) = delete;
-    pointee(pointee &&) = delete;
-    pointee &operator=(const pointee &) = delete;
-    pointee &operator=(pointee &&) = delete;
-};
-
-inline std::unique_ptr<pointee> make_unique_pointee() {
-    return std::unique_ptr<pointee>(new pointee);
-}
-
-inline std::shared_ptr<pointee> make_shared_pointee() {
-    return std::unique_ptr<pointee>(new pointee);
-}
-
-inline int pass_unique_pointee(std::unique_ptr<pointee> ptr) {
-    return 4000 + ptr->get_int();
-}
-
-inline int pass_shared_pointee(std::shared_ptr<pointee> ptr) {
-    return 5000 + ptr->get_int();
-}
-
-inline pointee* get_static_pointee() {
-  static pointee cpp_instance;
-  return &cpp_instance;
-}
-
-TEST_SUBMODULE(holder_shared_ptr, m) {
-    m.def("to_cout", to_cout);
-
-    py::class_<pointee, std::shared_ptr<pointee>>(m, "pointee")
-        .def(py::init<>())
-        .def("get_int", &pointee::get_int);
-
-    m.def("make_unique_pointee", make_unique_pointee);
-    m.def("make_shared_pointee", make_shared_pointee);
-    // m.def("pass_unique_pointee", pass_unique_pointee);
-    m.def("pass_shared_pointee", pass_shared_pointee);
-
-    m.def("get_static_pointee",
-          get_static_pointee, py::return_value_policy::reference);
-}
-
-} // namespace holder_shared_ptr
-} // namespace pybind11_tests

tests/test_holder_shared_ptr.py

-# -*- coding: utf-8 -*-
-# KEEP IN SYNC WITH test_holder_unique_ptr.py
-import pytest
-
-from pybind11_tests import holder_shared_ptr as m
-
-
-def test_make_unique_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("make_unique_pointee")
-    obj = m.make_unique_pointee()
-    assert obj.get_int() == 213
-    m.to_cout("")
-
-
-def test_make_shared_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("make_shared_pointee")
-    obj = m.make_shared_pointee()
-    assert obj.get_int() == 213
-    m.to_cout("")
-
-
-def test_pass_unique_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("pass_unique_pointee")
-    obj = m.make_shared_pointee()
-    assert obj.get_int() == 213
-    i = m.pass_unique_pointee(obj)
-    assert i == 4213
-    m.to_cout("")
-
-
-def test_pass_shared_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("pass_shared_pointee")
-    obj = m.make_shared_pointee()
-    assert obj.get_int() == 213
-    i = m.pass_shared_pointee(obj)
-    assert i == 5213
-    m.to_cout("")
-
-
-def test_get_static_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("get_static_pointee")
-    obj = m.get_static_pointee()
-    assert obj.get_int() == 213
-    with pytest.raises(RuntimeError) as excinfo:
-        m.pass_shared_pointee(obj)
-    assert "Unable to cast from non-held to held instance" in str(excinfo.value)

tests/test_holder_unique_ptr.cpp

-// KEEP IN SYNC WITH test_holder_shared_ptr.cpp
-
-#include "pybind11_tests.h"
-
-#include <iostream>
-#include <memory>
-
-namespace pybind11_tests {
-namespace holder_unique_ptr {
-
-inline void to_cout(std::string text) { std::cout << text << std::endl; }
-
-class pointee { // NOT copyable.
-  public:
-    pointee() { to_cout("pointee::pointee()"); }
-
-    int get_int() const {
-        to_cout("pointee::get_int()");
-        return 213;
-    }
-
-    ~pointee() { to_cout("~pointee()"); }
-
-  private:
-    pointee(const pointee &) = delete;
-    pointee(pointee &&) = delete;
-    pointee &operator=(const pointee &) = delete;
-    pointee &operator=(pointee &&) = delete;
-};
-
-inline std::unique_ptr<pointee> make_unique_pointee() {
-    return std::unique_ptr<pointee>(new pointee);
-}
-
-inline std::shared_ptr<pointee> make_shared_pointee() {
-    return std::unique_ptr<pointee>(new pointee);
-}
-
-inline int pass_unique_pointee(std::unique_ptr<pointee> ptr) {
-    return 4000 + ptr->get_int();
-}
-
-inline int pass_shared_pointee(std::shared_ptr<pointee> ptr) {
-    return 5000 + ptr->get_int();
-}
-
-inline pointee* get_static_pointee() {
-  static pointee cpp_instance;
-  return &cpp_instance;
-}
-
-TEST_SUBMODULE(holder_unique_ptr, m) {
-    m.def("to_cout", to_cout);
-
-    py::class_<pointee>(m, "pointee")
-        .def(py::init<>())
-        .def("get_int", &pointee::get_int);
-
-    m.def("make_unique_pointee", make_unique_pointee);
-    m.def("make_shared_pointee", make_shared_pointee);
-    // m.def("pass_unique_pointee", pass_unique_pointee);
-    m.def("pass_shared_pointee", pass_shared_pointee);
-
-    m.def("get_static_pointee",
-          get_static_pointee, py::return_value_policy::reference);
-}
-
-} // namespace holder_unique_ptr
-} // namespace pybind11_tests

tests/test_holder_unique_ptr.py

-# -*- coding: utf-8 -*-
-# KEEP IN SYNC WITH test_holder_shared_ptr.py
-import pytest
-
-from pybind11_tests import holder_unique_ptr as m
-
-
-def test_make_unique_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("make_unique_pointee")
-    obj = m.make_unique_pointee()
-    assert obj.get_int() == 213
-    m.to_cout("")
-
-
-def test_make_shared_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("make_shared_pointee")
-    obj = m.make_shared_pointee()
-    assert obj.get_int() == 213
-    m.to_cout("")
-
-
-def test_pass_unique_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("pass_unique_pointee")
-    obj = m.make_unique_pointee()
-    assert obj.get_int() == 213
-    i = m.pass_unique_pointee(obj)
-    assert i == 4213
-    m.to_cout("")
-
-
-def test_pass_shared_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("pass_shared_pointee")
-    obj = m.make_unique_pointee()
-    assert obj.get_int() == 213
-    i = m.pass_shared_pointee(obj)
-    assert i == 5213
-    m.to_cout("")
-
-
-def test_get_static_pointee():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("get_static_pointee")
-    obj = m.get_static_pointee()
-    assert obj.get_int() == 213
-    with pytest.raises(RuntimeError) as excinfo:
-        m.pass_unique_pointee(obj)
-    assert "Unable to cast from non-held to held instance" in str(excinfo.value)

tests/test_private_first_base.cpp

-// Demonstration of UB (Undefined Behavior) in handling of polymorphic pointers,
-// specifically:
-// https://github.com/pybind/pybind11/blob/30eb39ed79d1e2eeff15219ac00773034300a5e6/include/pybind11/cast.h#L229
-//     `return reinterpret_cast<V *&>(vh[0]);`
-// casts a `void` pointer to a `base`. The `void` pointer is obtained through
-// a `dynamic_cast` here:
-// https://github.com/pybind/pybind11/blob/30eb39ed79d1e2eeff15219ac00773034300a5e6/include/pybind11/cast.h#L852
-//     `return dynamic_cast<const void*>(src);`
-// The `dynamic_cast` is well-defined:
-// https://en.cppreference.com/w/cpp/language/dynamic_cast
-//     4) If expression is a pointer to a polymorphic type, and new-type
-//        is a pointer to void, the result is a pointer to the most derived
-//        object pointed or referenced by expression.
-// But the `reinterpret_cast` above is UB: `test_make_drvd_pass_base` in
-// `test_private_first_base.py` fails with a Segmentation Fault (Linux,
-// clang++ -std=c++17).
-// The only well-defined cast is back to a `drvd` pointer (`static_cast` can be
-// used), which can then safely be cast up to a `base` pointer. Note that
-// `test_make_drvd_up_cast_pass_drvd` passes because the `void` pointer is cast
-// to `drvd` pointer in this situation.
-
-#include "pybind11_tests.h"
-
-namespace pybind11_tests {
-namespace private_first_base {
-
-struct base {
-  base() : base_id(100) {}
-  virtual ~base() = default;
-  virtual int id() const { return base_id; }
-  base(const base&) = delete;
-  int base_id;
-};
-
-struct private_first_base {  // Any class with a virtual function will do.
-  virtual void some_other_virtual_function() const {}
-  virtual ~private_first_base() = default;
-};
-
-struct drvd : private private_first_base, public base {
-  int id() const override { return 2 * base_id; }
-};
-
-inline drvd* make_drvd() { return new drvd; }
-inline base* make_drvd_up_cast() { return new drvd; }
-
-inline int pass_base(const base* b) { return b->id(); }
-inline int pass_drvd(const drvd* d) { return d->id(); }
-
-TEST_SUBMODULE(private_first_base, m) {
-  py::class_<base>(m, "base");
-  py::class_<drvd, base>(m, "drvd");
-
-  m.def("make_drvd", make_drvd,
-        py::return_value_policy::take_ownership);
-  m.def("make_drvd_up_cast", make_drvd_up_cast,
-        py::return_value_policy::take_ownership);
-  m.def("pass_base", pass_base);
-  m.def("pass_drvd", pass_drvd);
-}
-
-}  // namespace private_first_base
-}  // namespace pybind11_tests

tests/test_private_first_base.py

-# -*- coding: utf-8 -*-
-
-from pybind11_tests import private_first_base as m
-
-
-def test_make_drvd_pass_base():
-    d = m.make_drvd()
-    i = m.pass_base(d)
-    assert i == 200
-
-
-def test_make_drvd_up_cast_pass_drvd():
-    b = m.make_drvd_up_cast()
-    # the base return is down-cast immediately.
-    assert b.__class__.__name__ == "drvd"
-    i = m.pass_drvd(b)
-    assert i == 200

tests/test_smart_ptr_base_derived.cpp

-#include "pybind11_tests.h"
-
-#include <iostream>
-#include <memory>
-
-namespace pybind11_tests {
-namespace smart_ptr_base_derived {
-
-inline void to_cout(std::string text) { std::cout << text << std::endl; }
-
-class cbase {
- public:
-  int get_int() const { return 90146438; }
-};
-
-class cderived : public cbase {
- public:
-  // Printing from constructor & destructor for simple external validation.
-  cderived() {
-    std::cout << std::endl << "cderived+" << std::endl;
-  }
-  ~cderived() {
-    std::cout << std::endl << "cderived-" << std::endl;
-  }
-  int get_int() const { return 31607978; }
-  int base_get_int(const cbase& base) { return get_int() + base.get_int(); }
-};
-
-class vbase {
- public:
-  virtual ~vbase() {}
-  virtual int get_int() const = 0;
-};
-
-class vderived : public vbase {
- public:
-  // Printing from constructor & destructor for simple external validation.
-  vderived() {
-    std::cout << std::endl << "vderived+" << std::endl;
-  }
-  ~vderived() {
-    std::cout << std::endl << "vderived-" << std::endl;
-  }
-  int get_int() const override { return 29852452; }
-  int base_get_int(const vbase& base) { return get_int() + base.get_int(); }
-};
-
-class vrederived : public vderived {};
-
-inline std::unique_ptr<cbase>
-make_unique_cderived_up_cast() {
-  // Undefined Behavior (pure C++ problem, NOT a pybind11 problem):
-  // cderived destructor does not run.
-  return std::unique_ptr<cderived>(new cderived);
-}
-
-inline std::shared_ptr<cderived>
-make_shared_cderived(bool use_custom_deleter = false) {
-  if (use_custom_deleter) {
-    return std::shared_ptr<cderived>(
-        new cderived, [](cderived *p) { delete p; });
-  }
-  return std::shared_ptr<cderived>(new cderived);
-}
-
-inline std::shared_ptr<cbase>
-make_shared_cderived_up_cast(bool use_custom_deleter = false) {
-  return make_shared_cderived(use_custom_deleter);
-}
-
-inline int pass_unique_cbase(std::unique_ptr<cbase> cb) {
-  return cb->get_int();
-}
-
-inline int pass_shared_cbase(std::shared_ptr<cbase> cb) {
-  return cb->get_int();
-}
-
-inline int pass_shared_cderived(std::shared_ptr<cderived> cd) {
-  return cd->get_int();
-}
-
-inline std::unique_ptr<vbase>
-make_unique_vderived_up_cast() {
-  // Well-defined behavior because vderived has a virtual destructor.
-  return std::unique_ptr<vderived>(new vderived);
-}
-
-inline std::shared_ptr<vderived>
-make_shared_vderived(bool use_custom_deleter = false) {
-  if (use_custom_deleter) {
-    return std::shared_ptr<vderived>(
-        new vderived, [](vderived *p) { delete p; });
-  }
-  return std::shared_ptr<vderived>(new vderived);
-}
-
-inline std::shared_ptr<vbase>
-make_shared_vderived_up_cast(bool use_custom_deleter = false) {
-  return make_shared_vderived(use_custom_deleter);
-}
-
-inline int pass_unique_vbase(std::unique_ptr<vbase> vb) {
-  return vb->get_int();
-}
-
-inline int pass_shared_vbase(std::shared_ptr<vbase> vb) {
-  return vb->get_int();
-}
-
-inline int pass_shared_vderived(std::shared_ptr<vderived> vd) {
-  return vd->get_int();
-}
-
-inline int pass_shared_vrederived(std::shared_ptr<vrederived> vr) {
-  return vr->get_int();
-}
-
-TEST_SUBMODULE(smart_ptr_base_derived, m) {
-    m.def("to_cout", to_cout);
-
-    py::class_<cbase, std::shared_ptr<cbase>>(m, "cbase")
-        .def(py::init<>())
-        .def("get_int", &cbase::get_int);
-
-    py::class_<cderived, cbase, std::shared_ptr<cderived>>(m, "cderived")
-        .def(py::init<>())
-        .def("get_int", &cderived::get_int);
-
-    py::class_<vbase, std::shared_ptr<vbase>>(m, "vbase")
-        .def("get_int", &vbase::get_int);
-
-    py::class_<vderived, vbase, std::shared_ptr<vderived>>(m, "vderived")
-        .def(py::init<>());
-
-    py::class_<vrederived, vderived, std::shared_ptr<vrederived>>(m, "vrederived")
-        .def(py::init<>());
-
-    m.def("make_shared_cderived",
-          make_shared_cderived,
-          py::arg("use_custom_deleter") = false);
-    m.def("make_shared_cderived_up_cast",
-          make_shared_cderived_up_cast,
-          py::arg("use_custom_deleter") = false);
-    m.def("pass_shared_cbase", pass_shared_cbase);
-    m.def("pass_shared_cderived", pass_shared_cderived);
-
-    m.def("make_shared_vderived",
-          make_shared_vderived,
-          py::arg("use_custom_deleter") = false);
-    m.def("make_shared_vderived_up_cast",
-          make_shared_vderived_up_cast,
-          py::arg("use_custom_deleter") = false);
-    m.def("pass_shared_vbase", pass_shared_vbase);
-    m.def("pass_shared_vderived", pass_shared_vderived);
-    m.def("pass_shared_vrederived", pass_shared_vrederived);
-}
-
-}  // namespace smart_ptr_base_derived
-}  // namespace pybind11_tests

tests/test_smart_ptr_base_derived.py

-# -*- coding: utf-8 -*-
-import pytest
-
-from pybind11_tests import smart_ptr_base_derived as m
-
-CBASE_GET_INT_RESULT = 90146438
-CDERIVED_GET_INT_RESULT = 31607978
-VDERIVED_GET_INT_RESULT = 29852452
-
-
-def test_concrete():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("make_shared_cderived")
-    cd = m.make_shared_cderived()
-    assert cd.get_int() == CDERIVED_GET_INT_RESULT
-    m.pass_shared_cderived(cd)
-    m.pass_shared_cbase(cd)
-    cb = m.make_shared_cderived_up_cast()
-    assert cb.get_int() == CBASE_GET_INT_RESULT
-    m.pass_shared_cbase(cb)
-    with pytest.raises(TypeError):
-        m.pass_shared_cderived(cb)
-    m.to_cout("")
-
-
-def test_virtual():
-    m.to_cout("")
-    m.to_cout("")
-    m.to_cout("make_shared_vderived")
-    vd = m.make_shared_vderived()
-    assert vd.get_int() == VDERIVED_GET_INT_RESULT
-    m.pass_shared_vderived(vd)
-    m.pass_shared_vbase(vd)
-    vd_uc = m.make_shared_vderived_up_cast()
-    assert vd_uc.get_int() == VDERIVED_GET_INT_RESULT
-    assert isinstance(vd_uc, m.vderived)  # pybind11 un-did upcast.
-    m.pass_shared_vbase(vd_uc)
-    m.pass_shared_vderived(vd_uc)
-    with pytest.raises(TypeError):
-        m.pass_shared_vrederived(vd_uc)
-    m.to_cout("")

tests/test_smart_ptr_private_first_base.cpp

-// Demonstration of Undefined Behavior in handling of shared_ptr holder,
-// specifically:
-// https://github.com/pybind/pybind11/blob/30eb39ed79d1e2eeff15219ac00773034300a5e6/include/pybind11/cast.h#L235
-//     `return reinterpret_cast<H &>(vh[1]);`
-// indirectly casts a `shared_ptr<drvd>` reference to a `shared_ptr<base>`.
-// Similarly:
-// https://github.com/pybind/pybind11/blob/30eb39ed79d1e2eeff15219ac00773034300a5e6/include/pybind11/pybind11.h#L1505
-//     `init_holder(inst, v_h, (const holder_type *) holder_ptr, v_h.value_ptr<type>());`
-// explictly casts a `shared_ptr<base>` reference to a `shared_ptr<drvd>`.
-// Both tests in `test_smart_ptr_private_first_base.py` fail with a
-// Segmentation Fault (Linux, clang++ -std=c++17).
-
-#include <memory>
-
-#include "pybind11_tests.h"
-
-namespace pybind11_tests {
-namespace smart_ptr_private_first_base {
-
-struct base {
-  base() : base_id(100) {}
-  virtual ~base() = default;
-  virtual int id() const { return base_id; }
-  int base_id;
-};
-
-struct private_first_base {  // Any class with a virtual function will do.
-  virtual void some_other_virtual_function() const {}
-  virtual ~private_first_base() = default;
-};
-
-struct drvd : private private_first_base, public base {
-  int id() const override { return 2 * base_id; }
-};
-
-inline std::shared_ptr<drvd> make_shared_drvd() {
-  return std::shared_ptr<drvd>(new drvd);
-}
-
-inline std::shared_ptr<base> make_shared_drvd_up_cast() {
-  return std::shared_ptr<base>(new drvd);
-}
-
-inline int pass_shared_base(std::shared_ptr<base> b) { return b->id(); }
-inline int pass_shared_drvd(std::shared_ptr<drvd> d) { return d->id(); }
-
-TEST_SUBMODULE(smart_ptr_private_first_base, m) {
-  py::class_<base, std::shared_ptr<base>>(m, "base");
-  py::class_<drvd, base, std::shared_ptr<drvd>>(m, "drvd");
-
-  m.def("make_shared_drvd", make_shared_drvd);
-  m.def("make_shared_drvd_up_cast", make_shared_drvd_up_cast);
-  m.def("pass_shared_base", pass_shared_base);
-  m.def("pass_shared_drvd", pass_shared_drvd);
-}
-
-}  // namespace smart_ptr_private_first_base
-}  // namespace pybind11_tests

tests/test_smart_ptr_private_first_base.py

-# -*- coding: utf-8 -*-
-
-from pybind11_tests import smart_ptr_private_first_base as m
-
-
-def test_make_drvd_pass_base():
-    d = m.make_shared_drvd()
-    i = m.pass_shared_base(d)
-    assert i == 200
-
-
-def test_make_drvd_up_cast_pass_drvd():
-    b = m.make_shared_drvd_up_cast()
-    # the base return is down-cast immediately.
-    assert b.__class__.__name__ == "drvd"
-    i = m.pass_shared_drvd(b)
-    assert i == 200