fix: use sys._is_immortal

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

tests/pybind11_tests.cpp

@@ -75,15 +75,6 @@ const char *cpp_std() {
 #endif
 }
 
-bool is_immortal(py::handle object) {
-    // If Python doesn't support immortal objects, this returns False
-#if PY_VERSION_HEX >= 0x030E0000
-    return PyUnstable_IsImmortal(object.ptr()) != 0;
-#else
-    return Py_REFCNT(object.ptr()) == UINT32_MAX;
-#endif
-}
-
 PYBIND11_MODULE(pybind11_tests, m, py::mod_gil_not_used()) {
     m.doc() = "pybind11 test module";
 
@@ -114,8 +105,6 @@ PYBIND11_MODULE(pybind11_tests, m, py::mod_gil_not_used()) {
     m.attr("detailed_error_messages_enabled") = false;
 #endif
 
-    m.def("is_immortal", &is_immortal, "Returns true if Python supports it and the object is immortal");
-
     py::class_<UserType>(m, "UserType", "A `py::class_` type for testing")
         .def(py::init<>())
         .def(py::init<int>())

tests/test_class.py

@@ -6,9 +6,17 @@
 import pytest
 
 import env
-from pybind11_tests import is_immortal, ConstructorStats, UserType
+from pybind11_tests import ConstructorStats, UserType
 from pybind11_tests import class_ as m
 
+UINT32MAX = 2**32 - 1
+
+
+def refcount_immortal(ob: object) -> int:
+    if _is_immortal := getattr(sys, "_is_immortal", None):
+        return UINT32MAX if _is_immortal(ob) else sys.getrefcount(ob)
+    return sys.getrefcount(ob)
+
 
 def test_obj_class_name():
     expected_name = "UserType" if env.PYPY else "pybind11_tests.UserType"
@@ -382,24 +390,21 @@ def test_brace_initialization():
 @pytest.mark.xfail("env.PYPY or env.GRAALPY")
 def test_class_refcount():
     """Instances must correctly increase/decrease the reference count of their types (#1029)"""
-    from sys import getrefcount
 
     class PyDog(m.Dog):
         pass
 
     for cls in m.Dog, PyDog:
-        refcount_1 = getrefcount(cls)
+        refcount_1 = refcount_immortal(cls)
         molly = [cls("Molly") for _ in range(10)]
-        refcount_2 = getrefcount(cls)
+        refcount_2 = refcount_immortal(cls)
 
         del molly
         pytest.gc_collect()
-        refcount_3 = getrefcount(cls)
+        refcount_3 = refcount_immortal(cls)
 
         assert refcount_1 == refcount_3
-        assert (refcount_2 > refcount_1) or (
-            is_immortal(refcount_2) and is_immortal(refcount_1)
-        )
+        assert (refcount_2 > refcount_1) or (refcount_2 == refcount_1 == UINT32MAX)
 
 
 def test_reentrant_implicit_conversion_failure(msg):