Backport: gh-118207: Rename the COMMON_FIELDS macro in funcobject.h a…

…nd undef it after use

Summary:
supersedes D56454529 by backporting the upstream version instead of an internal patch

upstream issue: python/cpython#118207
upstream PR: python/cpython#118269

still undef'ing the macro, but also renaming it to have `_Py` prefix, for consistency, and to avoid conflicts if the same name is already defined before including `Python.h`

Reviewed By: aleivag

Differential Revision: D56579827

fbshipit-source-id: c8260818f5901bc9c3eb582999575af9c64f189f

Include/cpython/funcobject.h

@@ -8,7 +8,7 @@ extern "C" {
 #endif
 
 
-#define COMMON_FIELDS(PREFIX) \
+#define _Py_COMMON_FIELDS(PREFIX) \
     PyObject *PREFIX ## globals; \
     PyObject *PREFIX ## builtins; \
     PyObject *PREFIX ## name; \
@@ -19,7 +19,7 @@ extern "C" {
     PyObject *PREFIX ## closure;     /* NULL or a tuple of cell objects */
 
 typedef struct {
-    COMMON_FIELDS(fc_)
+    _Py_COMMON_FIELDS(fc_)
 } PyFrameConstructor;
 
 /* Function objects and code objects should not be confused with each other:
@@ -35,7 +35,7 @@ typedef struct {
 
 typedef struct {
     PyObject_HEAD
-    COMMON_FIELDS(func_)
+    _Py_COMMON_FIELDS(func_)
     PyObject *func_doc;         /* The __doc__ attribute, can be anything */
     PyObject *func_dict;        /* The __dict__ attribute, a dict or NULL */
     PyObject *func_weakreflist; /* List of weak references */
@@ -60,9 +60,7 @@ typedef struct {
      */
 } PyFunctionObject;
 
-// START META PATCH (undef COMMON_FIELDS to avoid leaking into C++ code)
-#undef COMMON_FIELDS
-// END META PATCH
+#undef _Py_COMMON_FIELDS
 
 PyAPI_DATA(PyTypeObject) PyFunction_Type;