tests: add ABI check

.github/workflows/ci.yml

@@ -176,6 +176,11 @@ jobs:
       run: pytest tests/extra_setuptools
       if: "!(matrix.runs-on == 'windows-2022')"
 
+    # This tests ABI compatibility
+    - name: ABI test
+      if: matrix.python != '3.11-dev'
+      run: pytest tests/extra_abi
+
 
   deadsnakes:
     strategy:

.gitignore

@@ -44,3 +44,4 @@ pybind11Targets.cmake
 /docs/_build/*
 .ipynb_checkpoints/
 tests/main.cpp
+tests/*/temp*

noxfile.py

@@ -61,6 +61,23 @@ def tests_packaging(session: nox.Session) -> None:
     session.run("pytest", "tests/extra_python_package", *session.posargs)
 
 
+@nox.session
+def tests_abi(session: nox.Session) -> None:
+    """
+    Run the abi checker.
+    """
+
+    session.install("pybind11==2.8.0", "--no-build-isolation")
+    session.install(
+        "tests/extra_abi", "--no-build-isolation", env={"EXAMPLE_NAME": "pet"}
+    )
+    session.install(".", "--no-build-isolation")
+    session.install(
+        "tests/extra_abi", "--no-build-isolation", env={"EXAMPLE_NAME": "dog"}
+    )
+    session.run("python", "tests/extra_abi/check_installed.py")
+
+
 @nox.session(reuse_venv=True)
 def docs(session: nox.Session) -> None:
     """

tests/conftest.py

@@ -13,7 +13,10 @@
 import pytest
 
 # Early diagnostic for failed imports
-import pybind11_tests
+try:
+    import pybind11_tests
+except ModuleNotFoundError:
+    pybind11_tests = None
 
 _long_marker = re.compile(r"([0-9])L")
 _hexadecimal = re.compile(r"0x[0-9a-fA-F]+")
@@ -201,13 +204,14 @@ def pytest_configure():
 
 
 def pytest_report_header(config):
-    del config  # Unused.
-    assert (
-        pybind11_tests.compiler_info is not None
-    ), "Please update pybind11_tests.cpp if this assert fails."
-    return (
-        "C++ Info:"
-        f" {pybind11_tests.compiler_info}"
-        f" {pybind11_tests.cpp_std}"
-        f" {pybind11_tests.PYBIND11_INTERNALS_ID}"
-    )
+    if pybind11_tests is not None:
+        del config  # Unused.
+        assert (
+            pybind11_tests.compiler_info is not None
+        ), "Please update pybind11_tests.cpp if this assert fails."
+        return (
+            "C++ Info:"
+            f" {pybind11_tests.compiler_info}"
+            f" {pybind11_tests.cpp_std}"
+            f" {pybind11_tests.PYBIND11_INTERNALS_ID}"
+        )

tests/extra_abi/check_installed.py

@@ -0,0 +1,13 @@
+try:
+    import dog
+
+    raise RuntimeError("Broken! Dog must require Pet to be loaded")
+except ImportError:
+    import pet  # noqa: F401
+
+import dog  # noqa: F811
+
+d = dog.Dog("Bluey")
+
+d.bark()
+assert d.name == "Bluey"

tests/extra_abi/dog.cpp

@@ -0,0 +1,11 @@
+#include <pybind11/pybind11.h>
+
+#include "dog.hpp"
+
+#include <string>
+
+namespace py = pybind11;
+
+PYBIND11_MODULE(dog, m) {
+    py::class_<Dog, Pet>(m, "Dog").def(py::init<const std::string &>()).def("bark", &Dog::bark);
+}

tests/extra_abi/dog.hpp

@@ -0,0 +1,10 @@
+#include <pybind11/pybind11.h>
+
+#include "pet.hpp"
+
+#include <string>
+
+struct PYBIND11_EXPORT Dog : Pet {
+    explicit Dog(const std::string &name) : Pet(name) {}
+    std::string bark() const { return "woof!"; }
+};

tests/extra_abi/pet.cpp

@@ -0,0 +1,12 @@
+#include <pybind11/pybind11.h>
+
+#include "pet.hpp"
+
+#include <string>
+
+namespace py = pybind11;
+
+PYBIND11_MODULE(pet, m) {
+    py::class_<Pet> pet(m, "Pet");
+    pet.def(py::init<const std::string &>()).def_readwrite("name", &Pet::name);
+}

tests/extra_abi/pet.hpp

@@ -0,0 +1,6 @@
+#include <string>
+
+struct Pet {
+    explicit Pet(const std::string &name) : name(name) {}
+    std::string name;
+};

tests/extra_abi/setup.py

@@ -0,0 +1,20 @@
+import os
+import sys
+
+from setuptools import setup
+
+from pybind11.setup_helpers import Pybind11Extension
+
+name = os.environ["EXAMPLE_NAME"]
+assert name in {"pet", "dog"}
+
+
+ext = Pybind11Extension(
+    name,
+    [f"{name}.cpp"],
+    include_dirs=["."],
+    cxx_std=11,
+    extra_compile_args=["/d2FH4-"] if sys.platform.startswith("win32") else [],
+)
+
+setup(name=name, version="0.0.0", ext_modules=[ext])

tests/extra_abi/test_venv_abi.py

@@ -0,0 +1,16 @@
+from pathlib import Path
+
+DIR = Path(__file__).parent.resolve()
+
+
+def test_build_import(virtualenv):
+    virtualenv.run('pip install "pybind11==2.8.0" --no-build-isolation')
+    virtualenv.env["EXAMPLE_NAME"] = "pet"
+    virtualenv.run(f"pip install {DIR} --no-build-isolation")
+
+    virtualenv.run(f"pip install {DIR.parent.parent} --no-build-isolation")
+    virtualenv.env["EXAMPLE_NAME"] = "dog"
+    virtualenv.run(f"pip install {DIR} --no-build-isolation")
+
+    script = DIR / "check_installed.py"
+    virtualenv.run(f"python {script}")

tests/requirements.txt

@@ -5,5 +5,6 @@ numpy==1.21.5; platform_python_implementation!="PyPy" and python_version>="3.7"
 numpy==1.22.2; platform_python_implementation!="PyPy" and python_version>="3.10" and python_version<"3.11"
 pytest==7.0.0
 pytest-timeout
+pytest-virtualenv
 scipy==1.5.4; platform_python_implementation!="PyPy" and python_version<"3.10"
 scipy==1.8.0; platform_python_implementation!="PyPy" and python_version=="3.10"