Merge pull request #482 from tacaswell/cp315_compat

FIX: add macros to guard against removed enum

Author: jamadden

src/greenlet/TGreenlet.cpp

@@ -633,7 +633,13 @@ void GREENLET_NOINLINE(Greenlet::expose_frames)()
             // directly.  This is important since GetFrameObject might
             // lazily _create_ the frame object and we don't want the
             // interpreter to lose track of it.
+            //
+            #if !GREENLET_PY315
+            // This enum value was removed in
+            //    https://github.com/python/cpython/pull/141108
+
             assert(iframe_copy.owner != FRAME_OWNED_BY_CSTACK);
+            #endif
 
             // We really want to just write:
             //     PyFrameObject* frame = _PyFrame_GetFrameObject(iframe);

src/greenlet/greenlet_cpython_compat.hpp

@@ -67,6 +67,12 @@ Greenlet won't compile on anything older than Python 3.11 alpha 4 (see
 #    define GREENLET_PY314 0
 #endif
 
+#if PY_VERSION_HEX >= 0x30F0000
+#    define GREENLET_PY315 1
+#else
+#    define GREENLET_PY315 0
+#endif
+
 #ifndef Py_SET_REFCNT
 /* Py_REFCNT and Py_SIZE macros are converted to functions
 https://bugs.python.org/issue39573 */