Compatibility workaround to match 3.11a6 API

python · ncoghlan · Mar 19, 2022 · Mar 19, 2022 · Mar 19, 2022 · Mar 19, 2022
commit 32c224fc50d0d52a14b2134cbf6ad032b8f1e925
diff --git a/Include/internal/pycore_frame.h b/Include/internal/pycore_frame.h
@@ -109,6 +109,36 @@ typedef struct _Py_frame {
     PyObject *localsplus[1];
 } _Py_frame;
 
+#if !defined(_PY_FRAME_API_DISABLE_INTERIM_COMPAT_3_11a6)
+/* Interim compatibility for the internal frame API as shipped in 3.11a6
+ * Some projects (Cython, gevent, greenlet) are known to access the private
+ * frame API in CPython. This API has already changed twice for 3.11 (first
+ * with the structural split, then with the full object structure becoming
+ * opaque and internal struct gaining the `_Py` prefix). The recommended
+ * resolution is expected to change again once a proper public API for the
+ * required frame operations is defined (as discussed in
+ * https://github.com/faster-cpython/ideas/issues/309).
+ *
+ * This interim compatibility workaround enables the bpo-44800 struct and field
+ * name changes for CPython maintainability without forcing yet another interim
+ * code update on the affected projects. Since the workaround affects symbols
+ * without the `Py` or `_Py` prefix, a preprocessor symbol can be declared to
+ * disable the workaround: _PY_FRAME_API_DISABLE_INTERIM_COMPAT_3_11a6
+ */
+// Renamed frame data struct and fields
+typedef _Py_frame _PyInterpreterFrame;
+#define f_func func
+#define f_globals globals
+#define f_builtins builtins
+#define f_locals locals
+#define f_code code
+#define f_lasti lasti
+#define f_state state
+// Renamed frame object fields
+#define f_frame f_fdata
+#define _f_frame_data _f_owned_fdata
+#endif // End internal frame API compatibilty workaround
+
 static inline int _PyFrame_IsRunnable(_Py_frame *f) {
     return f->f_state < FRAME_EXECUTING;
 }

@@ -20,6 +20,23 @@ static PyMemberDef frame_memberlist[] = {
     {NULL}      /* Sentinel */
 };
 
+// Compile time check of interim Python 3.11a6 API compatibility aliases
+// Can be removed once the aliases are removed
+static_assert(OFF(f_fdata) == OFF(f_frame), "Incorrect alias for f_frame");
+static_assert(OFF(_f_owned_fdata) == OFF(_f_frame_data), "Incorrect alias for _f_frame_data");
+
+#define INTERIM_FRAME_DATA_ALIAS_CHECK(new_field) \
+    static_assert(offsetof(_Py_frame, new_field) == offsetof(_PyInterpreterFrame, f_##new_field), \
+                  "Incorrect alias for f_" #new_field )
+
+INTERIM_FRAME_DATA_ALIAS_CHECK(func);
+INTERIM_FRAME_DATA_ALIAS_CHECK(builtins);
+INTERIM_FRAME_DATA_ALIAS_CHECK(globals);
+INTERIM_FRAME_DATA_ALIAS_CHECK(locals);
+INTERIM_FRAME_DATA_ALIAS_CHECK(code);
+INTERIM_FRAME_DATA_ALIAS_CHECK(lasti);
+INTERIM_FRAME_DATA_ALIAS_CHECK(state);
+// End compatiblity alias check
 
 static PyObject *
 frame_getlocals(PyFrameObject *f, void *closure)