set _Py_OPAQUE_PYOBJECT for limited API free-threaded builds

Author: ngoldbaum

src/cffi/recompiler.py

@@ -9,7 +9,7 @@
 
 USE_LIMITED_API = ((sys.platform != 'win32' or sys.version_info < (3, 0) or
                    sys.version_info >= (3, 5)) and
-                   not sysconfig.get_config_var("Py_GIL_DISABLED"))  # free-threaded doesn't yet support limited API
+                   (not sysconfig.get_config_var("Py_GIL_DISABLED") or sys.version_info >= (3, 15)))  # free-threaded doesn't yet support limited API
 
 class GlobalExpr:
     def __init__(self, name, address, type_op, size=0, check_value=0):

src/cffi/setuptools_ext.py

@@ -104,10 +104,13 @@ def _set_py_limited_api(Extension, kwds):
             # warning.
             kwds['py_limited_api'] = True
 
-    if sysconfig.get_config_var("Py_GIL_DISABLED") and sys.version_info < (3, 15):
-        if kwds.get('py_limited_api'):
-            log.info("Ignoring py_limited_api=True for free-threaded build.")
-        kwds['py_limited_api'] = False
+    if sysconfig.get_config_var("Py_GIL_DISABLED"):
+        if sys.version_info < (3, 15):
+            if kwds.get('py_limited_api'):
+                log.info("Ignoring py_limited_api=True for free-threaded build.")
+            kwds['py_limited_api'] = False
+        else:
+            kwds.setdefault("define_macros", []).append(("_Py_OPAQUE_PYOBJECT", None))
 
     if kwds.get('py_limited_api') is False:
         # avoid setting Py_LIMITED_API if py_limited_api=False