bpo-35081: Make some _PyGC macros internal (GH-10507)

* Move "GC" macros together:

  * PyObject_IS_GC()
  * _Py_AS_GC()
  * _PyObject_GC_IS_TRACKED()
  * _PyObject_GC_MAY_BE_TRACKED()

* Mark other GC macros as internal (#ifdef Py_BUILD_CORE):

  * _PyGCHead_NEXT(g), _PyGCHead_SET_NEXT(g, p)
  * _PyGCHead_PREV(g), _PyGCHead_SET_PREV(g, p)
  * _PyGCHead_FINALIZED(g), _PyGCHead_SET_FINALIZED(g)
  * _PyGC_FINALIZED(o), _PyGC_SET_FINALIZED(o)
  * _PyObject_GC_TRACK(o), _PyObject_GC_UNTRACK(o)
  * _PyGC_PREV_MASK_FINALIZED
  * _PyGC_PREV_MASK_COLLECTING
  * _PyGC_PREV_SHIFT
  * _PyGC_PREV_MASK

* Replace _PyGC_generation0 with _PyRuntime.gc.generation0
* _queuemodule.c: replace _PyObject_GC_UNTRACK()
  with with PyObject_GC_UnTrack()
* Document that  _PyObject_GC_TRACK() _PyObject_GC_UNTRACK() macros
  have been removed from the public C API.

1 files changed, 3 insertions, 8 deletions

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index 7f54b6a..b739aac 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -61,11 +61,6 @@ Constructors for container types must conform to two rules:
    end of the constructor.
 
 
-.. c:function:: void _PyObject_GC_TRACK(PyObject *op)
-
-   A macro version of :c:func:`PyObject_GC_Track`.  It should not be used for
-   extension modules.
-
 Similarly, the deallocator for the object must conform to a similar pair of
 rules:
 
@@ -90,10 +85,10 @@ rules:
    the fields used by the :c:member:`~PyTypeObject.tp_traverse` handler become invalid.
 
 
-.. c:function:: void _PyObject_GC_UNTRACK(PyObject *op)
+.. versionchanged:: 3.8
 
-   A macro version of :c:func:`PyObject_GC_UnTrack`.  It should not be used for
-   extension modules.
+   The :c:func:`_PyObject_GC_TRACK` and :c:func:`_PyObject_GC_UNTRACK` macros
+   have been removed from the public C API.
 
 The :c:member:`~PyTypeObject.tp_traverse` handler accepts a function parameter of this type: