From 82638117156529b838bcfe0b6975f713b699fed1 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Sat, 14 Nov 2026 20:11:58 +0100
Subject: [PATCH] Test Py_SET_TYPE() on limited C API

---
 docs/api.rst                        |  2 ++
 tests/test_pythoncapi_compat.py     |  6 ++++--
 tests/test_pythoncapi_compat_cext.c | 11 ++++++++---
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/docs/api.rst b/docs/api.rst
index cf86c17..7f5ac3a 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -870,6 +870,8 @@ PyObject
 
    See `Py_SET_TYPE() documentation <https://docs.python.org/dev/c-api/structures.html#c.Py_SET_TYPE>`__.
 
+   Not available on Free Threading with limited C API 3.15 or newer (abi3t).
+
 .. c:function:: void Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size)
 
    See `Py_SET_SIZE() documentation <https://docs.python.org/dev/c-api/structures.html#c.Py_SET_SIZE>`__.
diff --git a/tests/test_pythoncapi_compat.py b/tests/test_pythoncapi_compat.py
index 8ef3f24..d6eff38 100644
--- a/tests/test_pythoncapi_compat.py
+++ b/tests/test_pythoncapi_compat.py
@@ -166,13 +166,15 @@ def run_tests(build_dir, module_name, std):
     if VERBOSE:
         empty_line = False
         for attr in ('__cplusplus', 'PY_VERSION', 'PY_VERSION_HEX',
-                     'PYPY_VERSION', 'PYPY_VERSION_NUM', 'Py_LIMITED_API'):
+                     'PYPY_VERSION', 'PYPY_VERSION_NUM', 'Py_LIMITED_API',
+                     'Py_TARGET_ABI3T'):
             try:
                 value = getattr(testmod, attr)
             except AttributeError:
                 pass
             else:
-                if attr in ('PY_VERSION_HEX', 'Py_LIMITED_API', 'PYPY_VERSION_NUM'):
+                if attr in ('PY_VERSION_HEX', 'Py_LIMITED_API',
+                            'PYPY_VERSION_NUM', 'Py_TARGET_ABI3T'):
                     value = "0x%x" % value
                 print("%s: %s" % (attr, value))
                 empty_line = True
diff --git a/tests/test_pythoncapi_compat_cext.c b/tests/test_pythoncapi_compat_cext.c
index 45a3d6e..aee2f35 100644
--- a/tests/test_pythoncapi_compat_cext.c
+++ b/tests/test_pythoncapi_compat_cext.c
@@ -102,8 +102,8 @@ test_object(PyObject *Py_UNUSED(module), PyObject* Py_UNUSED(ignored))
 
     // Py_SET_REFCNT
     Py_SET_REFCNT(obj, Py_REFCNT(obj));
-#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < _Py_PACK_VERSION(3, 10)
-    // Py_SET_TYPE
+    // Py_SET_TYPE. Not implemented in the abi3t.
+#ifndef Py_TARGET_ABI3T
     Py_SET_TYPE(obj, Py_TYPE(obj));
 #endif
     // Py_SET_SIZE
@@ -315,7 +315,7 @@ test_thread_state(PyObject *Py_UNUSED(module), PyObject* Py_UNUSED(ignored))
 static PyObject *
 test_interpreter(PyObject *Py_UNUSED(module), PyObject* Py_UNUSED(ignored))
 {
-    // On Windows,PyInterpreterState_Get() is not available in stable ABI 3.9,
+    // On Windows, PyInterpreterState_Get() is not available in stable ABI 3.9,
     // only in stable ABI 3.10. Don't test it on limited C API 3.9 on Unix to
     // make the test simpler.
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= _Py_PACK_VERSION(3, 10)
@@ -2802,6 +2802,11 @@ module_exec(PyObject *module)
         return -1;
     }
 #endif
+#ifdef Py_TARGET_ABI3T
+    if (PyModule_AddIntMacro(module, Py_TARGET_ABI3T)) {
+        return -1;
+    }
+#endif
 #if !defined(PYPY_VERSION) && !defined(Py_LIMITED_API)
     TryIncrefType.tp_name = "TryIncrefType";
     TryIncrefType.tp_basicsize = sizeof(PyObject);