From 8bb1fabd55c82b698484f925663885ed9f1fe652 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Sat, 11 Apr 2020 06:30:50 +0800
Subject: [PATCH 01/12] Convert PyObject_IS_GC() macro to a function

---
 Doc/c-api/gcsupport.rst                                |  6 ++++++
 Include/cpython/objimpl.h                              |  4 +---
 .../C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst     |  2 ++
 Modules/gcmodule.c                                     | 10 ++++++++++
 4 files changed, 19 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index 924a7fd2fda4d5..05d4647f430526 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -60,6 +60,12 @@ Constructors for container types must conform to two rules:
    followed by the :c:member:`~PyTypeObject.tp_traverse` handler become valid, usually near the
    end of the constructor.
 
+.. c:function:: int PyObject_IS_GC(PyObject *obj)
+
+   Return non-zero if the object have GC head. Return zero otherwise.
+
+   .. versionadded:: 3.9
+
 
 Similarly, the deallocator for the object must conform to a similar pair of
 rules:
diff --git a/Include/cpython/objimpl.h b/Include/cpython/objimpl.h
index 832622cb61921f..334327fbc32ffd 100644
--- a/Include/cpython/objimpl.h
+++ b/Include/cpython/objimpl.h
@@ -121,9 +121,7 @@ PyAPI_FUNC(Py_ssize_t) _PyGC_CollectIfEnabled(void);
 
 
 /* Test if an object has a GC head */
-#define PyObject_IS_GC(o) \
-    (PyType_IS_GC(Py_TYPE(o)) \
-     && (Py_TYPE(o)->tp_is_gc == NULL || Py_TYPE(o)->tp_is_gc(o)))
+PyAPI_FUNC(int) PyObject_IS_GC(PyObject *obj);
 
 /* GC information is stored BEFORE the object structure. */
 typedef struct {
diff --git a/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst b/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst
new file mode 100644
index 00000000000000..67f8b0f05efb5d
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst	
@@ -0,0 +1,2 @@
+Convert :c:fun:`PyObject_IS_GC` macro to a function to hide
+implementation details: the macro test an object have GC head or not.
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 1bc41fb83d8a60..52bf287af5fcd0 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -2203,6 +2203,16 @@ PyObject_GC_UnTrack(void *op_raw)
     }
 }
 
+/* Test if an object has a GC head */
+int
+PyObject_IS_GC(PyObject *obj)
+{
+    if (PyType_IS_GC(Py_TYPE(obj))) {
+        return (Py_TYPE(obj)->tp_is_gc == NULL || Py_TYPE(obj)->tp_is_gc(obj));
+    }
+    return 0;
+}
+
 static PyObject *
 _PyObject_GC_Alloc(int use_calloc, size_t basicsize)
 {

From be2bbab999b03d0a805ce7d422032cd1897fb6b9 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Sat, 11 Apr 2020 06:46:31 +0800
Subject: [PATCH 02/12] Update 2020-04-11-06-12-44.bpo-40170.cmM9oK.rst

Fix typo of news
---
 Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst b/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst
index 67f8b0f05efb5d..6ec5e17b1f03f8 100644
--- a/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst	
+++ b/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst	
@@ -1,2 +1,2 @@
-Convert :c:fun:`PyObject_IS_GC` macro to a function to hide
+Convert :c:func:`PyObject_IS_GC` macro to a function to hide
 implementation details: the macro test an object have GC head or not.

From 0783d0b42ab56d18197b1a1793b4cb3225259dae Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Mon, 13 Apr 2020 14:04:36 +0800
Subject: [PATCH 03/12] add _PyObject_IS_GC()

---
 Include/cpython/objimpl.h | 12 +++++++++++-
 Modules/gcmodule.c        | 21 +++++++++------------
 Objects/object.c          |  4 ++--
 Python/sysmodule.c        |  2 +-
 4 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/Include/cpython/objimpl.h b/Include/cpython/objimpl.h
index 334327fbc32ffd..2115e7732aa86d 100644
--- a/Include/cpython/objimpl.h
+++ b/Include/cpython/objimpl.h
@@ -123,6 +123,16 @@ PyAPI_FUNC(Py_ssize_t) _PyGC_CollectIfEnabled(void);
 /* Test if an object has a GC head */
 PyAPI_FUNC(int) PyObject_IS_GC(PyObject *obj);
 
+/* Fast inlined version of PyObject_IS_GC() */
+static inline int
+_PyObject_IS_GC(PyObject *obj)
+{
+    if (PyType_IS_GC(Py_TYPE(obj))) {
+        return (Py_TYPE(obj)->tp_is_gc == NULL || Py_TYPE(obj)->tp_is_gc(obj));
+    }
+    return 0;
+}
+
 /* GC information is stored BEFORE the object structure. */
 typedef struct {
     // Pointer to next object in the list.
@@ -142,7 +152,7 @@ typedef struct {
 /* True if the object may be tracked by the GC in the future, or already is.
    This can be useful to implement some optimizations. */
 #define _PyObject_GC_MAY_BE_TRACKED(obj) \
-    (PyObject_IS_GC(obj) && \
+    (_PyObject_IS_GC(obj) && \
         (!PyTuple_CheckExact(obj) || _PyObject_GC_IS_TRACKED(obj)))
 
 
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 9fab0189d710d4..cdba8ebe2a239e 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -441,7 +441,7 @@ visit_decref(PyObject *op, void *parent)
 {
     _PyObject_ASSERT(_PyObject_CAST(parent), !_PyObject_IsFreed(op));
 
-    if (PyObject_IS_GC(op)) {
+    if (_PyObject_IS_GC(op)) {
         PyGC_Head *gc = AS_GC(op);
         /* We're only interested in gc_refs for objects in the
          * generation being collected, which can be recognized
@@ -477,7 +477,7 @@ subtract_refs(PyGC_Head *containers)
 static int
 visit_reachable(PyObject *op, PyGC_Head *reachable)
 {
-    if (!PyObject_IS_GC(op)) {
+    if (!_PyObject_IS_GC(op)) {
         return 0;
     }
 
@@ -704,7 +704,7 @@ clear_unreachable_mask(PyGC_Head *unreachable)
 static int
 visit_move(PyObject *op, PyGC_Head *tolist)
 {
-    if (PyObject_IS_GC(op)) {
+    if (_PyObject_IS_GC(op)) {
         PyGC_Head *gc = AS_GC(op);
         if (gc_is_collecting(gc)) {
             gc_list_move(gc, tolist);
@@ -1715,7 +1715,7 @@ gc_get_referents(PyObject *self, PyObject *args)
         traverseproc traverse;
         PyObject *obj = PyTuple_GET_ITEM(args, i);
 
-        if (! PyObject_IS_GC(obj))
+        if (!_PyObject_IS_GC(obj))
             continue;
         traverse = Py_TYPE(obj)->tp_traverse;
         if (! traverse)
@@ -1855,7 +1855,7 @@ gc_is_tracked(PyObject *module, PyObject *obj)
 {
     PyObject *result;
 
-    if (PyObject_IS_GC(obj) && _PyObject_GC_IS_TRACKED(obj))
+    if (_PyObject_IS_GC(obj) && _PyObject_GC_IS_TRACKED(obj))
         result = Py_True;
     else
         result = Py_False;
@@ -1876,7 +1876,7 @@ static PyObject *
 gc_is_finalized(PyObject *module, PyObject *obj)
 /*[clinic end generated code: output=e1516ac119a918ed input=201d0c58f69ae390]*/
 {
-    if (PyObject_IS_GC(obj) && _PyGCHead_FINALIZED(AS_GC(obj))) {
+    if (_PyObject_IS_GC(obj) && _PyGCHead_FINALIZED(AS_GC(obj))) {
          Py_RETURN_TRUE;
     }
     Py_RETURN_FALSE;
@@ -2207,10 +2207,7 @@ PyObject_GC_UnTrack(void *op_raw)
 int
 PyObject_IS_GC(PyObject *obj)
 {
-    if (PyType_IS_GC(Py_TYPE(obj))) {
-        return (Py_TYPE(obj)->tp_is_gc == NULL || Py_TYPE(obj)->tp_is_gc(obj));
-    }
-    return 0;
+    return _PyObject_IS_GC(obj);
 }
 
 static PyObject *
@@ -2326,7 +2323,7 @@ PyObject_GC_Del(void *op)
 int
 PyObject_GC_IsTracked(PyObject* obj)
 {
-    if (PyObject_IS_GC(obj) && _PyObject_GC_IS_TRACKED(obj)) {
+    if (_PyObject_IS_GC(obj) && _PyObject_GC_IS_TRACKED(obj)) {
         return 1;
     }
     return 0;
@@ -2335,7 +2332,7 @@ PyObject_GC_IsTracked(PyObject* obj)
 int
 PyObject_GC_IsFinalized(PyObject *obj)
 {
-    if (PyObject_IS_GC(obj) && _PyGCHead_FINALIZED(AS_GC(obj))) {
+    if (_PyObject_IS_GC(obj) && _PyGCHead_FINALIZED(AS_GC(obj))) {
          return 1;
     }
     return 0;
diff --git a/Objects/object.c b/Objects/object.c
index ef4ba997de4273..b63cb4fd52892c 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -2030,7 +2030,7 @@ _PyTrash_deposit_object(PyObject *op)
     PyThreadState *tstate = _PyThreadState_GET();
     struct _gc_runtime_state *gcstate = &tstate->interp->gc;
 
-    _PyObject_ASSERT(op, PyObject_IS_GC(op));
+    _PyObject_ASSERT(op, _PyObject_IS_GC(op));
     _PyObject_ASSERT(op, !_PyObject_GC_IS_TRACKED(op));
     _PyObject_ASSERT(op, Py_REFCNT(op) == 0);
     _PyGCHead_SET_PREV(_Py_AS_GC(op), gcstate->trash_delete_later);
@@ -2042,7 +2042,7 @@ void
 _PyTrash_thread_deposit_object(PyObject *op)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    _PyObject_ASSERT(op, PyObject_IS_GC(op));
+    _PyObject_ASSERT(op, _PyObject_IS_GC(op));
     _PyObject_ASSERT(op, !_PyObject_GC_IS_TRACKED(op));
     _PyObject_ASSERT(op, Py_REFCNT(op) == 0);
     _PyGCHead_SET_PREV(_Py_AS_GC(op), tstate->trash_delete_later);
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 994e3582fe6b5c..fc192d70fd6576 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1679,7 +1679,7 @@ _PySys_GetSizeOf(PyObject *o)
     }
 
     /* add gc_head size */
-    if (PyObject_IS_GC(o))
+    if (_PyObject_IS_GC(o))
         return ((size_t)size) + sizeof(PyGC_Head);
     return (size_t)size;
 }

From c69d6972ecd69299da34473b5aac534f4a7a80a3 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Tue, 14 Apr 2020 19:31:20 +0800
Subject: [PATCH 04/12] update docs

---
 Doc/c-api/gcsupport.rst | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index 7bfdbf6e5c3b65..ea52ab3dd11495 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -63,9 +63,16 @@ Constructors for container types must conform to two rules:
 
 .. c:function:: int PyObject_IS_GC(PyObject *obj)
 
-   Return non-zero if the object have GC head. Return zero otherwise.
+   Return 0 if the object type does not have the :c:data:`Py_TPFLAGS_HAVE_GC` flag.
+   Otherwise, return non-zero if object type does not implement tp_is_gc slot or
+   if tp_is_gc(obj) is non-zero.
 
-   .. versionadded:: 3.9
+   For example, if *obj* is a type(`PyTypeObject`), check if *obj* has
+   the :c:data:`Py_TPFLAGS_HEAPTYPE` flag.
+
+   If the function returns non-zero, you can use :c:func:`PyObject_GC_ISTracked`
+   to check if the object is currently tracked by the GC.
+   Notice that if this function return zero, the object cannot be tracked the GC.
 
 
 .. c:function:: int PyObject_GC_IsTracked(PyObject *op)

From 1dd8dd213c53d9b8b6571eeb4cd743557f771229 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Tue, 14 Apr 2020 22:53:01 +0800
Subject: [PATCH 05/12] Update Doc/c-api/gcsupport.rst

Co-Authored-By: Victor Stinner <vstinner@python.org>
---
 Doc/c-api/gcsupport.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index ea52ab3dd11495..3116554d435f72 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -67,7 +67,7 @@ Constructors for container types must conform to two rules:
    Otherwise, return non-zero if object type does not implement tp_is_gc slot or
    if tp_is_gc(obj) is non-zero.
 
-   For example, if *obj* is a type(`PyTypeObject`), check if *obj* has
+   For example, if *obj* is a type (:c:type:`PyTypeObject`), check if *obj* has
    the :c:data:`Py_TPFLAGS_HEAPTYPE` flag.
 
    If the function returns non-zero, you can use :c:func:`PyObject_GC_ISTracked`

From 176f8a05aa765eec2146c9c36857c967400f671a Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Tue, 14 Apr 2020 22:55:31 +0800
Subject: [PATCH 06/12] Update Doc/c-api/gcsupport.rst

Co-Authored-By: Victor Stinner <vstinner@python.org>
---
 Doc/c-api/gcsupport.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index 3116554d435f72..fa0af6cb161ac0 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -64,8 +64,8 @@ Constructors for container types must conform to two rules:
 .. c:function:: int PyObject_IS_GC(PyObject *obj)
 
    Return 0 if the object type does not have the :c:data:`Py_TPFLAGS_HAVE_GC` flag.
-   Otherwise, return non-zero if object type does not implement tp_is_gc slot or
-   if tp_is_gc(obj) is non-zero.
+   Otherwise, return non-zero if object type does not implement ``tp_is_gc`` slot or
+   if ``tp_is_gc(obj)`` is non-zero.
 
    For example, if *obj* is a type (:c:type:`PyTypeObject`), check if *obj* has
    the :c:data:`Py_TPFLAGS_HEAPTYPE` flag.

From 8d680115dc2dd0f0e7ca76106e070ed254973df3 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Tue, 14 Apr 2020 23:16:11 +0800
Subject: [PATCH 07/12] update some descriptions

---
 Doc/c-api/gcsupport.rst   | 13 +++----------
 Include/cpython/objimpl.h |  7 +++----
 Modules/gcmodule.c        |  1 -
 3 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index fa0af6cb161ac0..b437e70b4bef3f 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -63,16 +63,9 @@ Constructors for container types must conform to two rules:
 
 .. c:function:: int PyObject_IS_GC(PyObject *obj)
 
-   Return 0 if the object type does not have the :c:data:`Py_TPFLAGS_HAVE_GC` flag.
-   Otherwise, return non-zero if object type does not implement ``tp_is_gc`` slot or
-   if ``tp_is_gc(obj)`` is non-zero.
-
-   For example, if *obj* is a type (:c:type:`PyTypeObject`), check if *obj* has
-   the :c:data:`Py_TPFLAGS_HEAPTYPE` flag.
-
-   If the function returns non-zero, you can use :c:func:`PyObject_GC_ISTracked`
-   to check if the object is currently tracked by the GC.
-   Notice that if this function return zero, the object cannot be tracked the GC.
+   Returns non-zero if the object implements the garbage collector protocol,
+   otherwise returns 0. The object cannot be tracked by the garbage collector
+   if this function return 0.
 
 
 .. c:function:: int PyObject_GC_IsTracked(PyObject *op)
diff --git a/Include/cpython/objimpl.h b/Include/cpython/objimpl.h
index 461e3de74b5a61..2c361ca8c18c20 100644
--- a/Include/cpython/objimpl.h
+++ b/Include/cpython/objimpl.h
@@ -127,10 +127,9 @@ PyAPI_FUNC(int) PyObject_IS_GC(PyObject *obj);
 static inline int
 _PyObject_IS_GC(PyObject *obj)
 {
-    if (PyType_IS_GC(Py_TYPE(obj))) {
-        return (Py_TYPE(obj)->tp_is_gc == NULL || Py_TYPE(obj)->tp_is_gc(obj));
-    }
-    return 0;
+    return (PyType_IS_GC(Py_TYPE(obj))
+            && (Py_TYPE(obj)->tp_is_gc == NULL
+                || Py_TYPE(obj)->tp_is_gc(obj)));
 }
 
 /* Code built with Py_BUILD_CORE must include pycore_gc.h instead which
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index cdba8ebe2a239e..5d635b553bfc9d 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -2203,7 +2203,6 @@ PyObject_GC_UnTrack(void *op_raw)
     }
 }
 
-/* Test if an object has a GC head */
 int
 PyObject_IS_GC(PyObject *obj)
 {

From ee0525bc84b86ed48be6ddd7ad1c09818d3c177c Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Tue, 14 Apr 2020 23:22:48 +0800
Subject: [PATCH 08/12] update docs

---
 Doc/c-api/gcsupport.rst | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index b437e70b4bef3f..9b3d7d8f52da17 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -64,8 +64,9 @@ Constructors for container types must conform to two rules:
 .. c:function:: int PyObject_IS_GC(PyObject *obj)
 
    Returns non-zero if the object implements the garbage collector protocol,
-   otherwise returns 0. The object cannot be tracked by the garbage collector
-   if this function return 0.
+   otherwise returns 0.
+   
+   The object cannot be tracked by the garbage collector if this function return 0.
 
 
 .. c:function:: int PyObject_GC_IsTracked(PyObject *op)

From a4d1a37c8e2d70c7bcdfb0366ad5abfe8c71b585 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Tue, 14 Apr 2020 23:24:38 +0800
Subject: [PATCH 09/12] fix typos

---
 Doc/c-api/gcsupport.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index 9b3d7d8f52da17..22de9866cc0555 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -66,7 +66,7 @@ Constructors for container types must conform to two rules:
    Returns non-zero if the object implements the garbage collector protocol,
    otherwise returns 0.
    
-   The object cannot be tracked by the garbage collector if this function return 0.
+   The object cannot be tracked by the garbage collector if this function returns 0.
 
 
 .. c:function:: int PyObject_GC_IsTracked(PyObject *op)

From bdc61b9fb8545fdb58c45abf26710caa6d3ffb88 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Wed, 15 Apr 2020 00:00:58 +0800
Subject: [PATCH 10/12] remove _PyObject_IS_GC() to pycore_object.h

---
 Include/cpython/objimpl.h        | 10 +---------
 Include/internal/pycore_object.h |  9 +++++++++
 Python/sysmodule.c               |  1 +
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/Include/cpython/objimpl.h b/Include/cpython/objimpl.h
index 2c361ca8c18c20..b835936db70112 100644
--- a/Include/cpython/objimpl.h
+++ b/Include/cpython/objimpl.h
@@ -120,17 +120,9 @@ PyAPI_FUNC(Py_ssize_t) _PyGC_CollectNoFail(void);
 PyAPI_FUNC(Py_ssize_t) _PyGC_CollectIfEnabled(void);
 
 
-/* Test if an object has a GC head */
+/* Test if an object implements the garbage collector protocol */
 PyAPI_FUNC(int) PyObject_IS_GC(PyObject *obj);
 
-/* Fast inlined version of PyObject_IS_GC() */
-static inline int
-_PyObject_IS_GC(PyObject *obj)
-{
-    return (PyType_IS_GC(Py_TYPE(obj))
-            && (Py_TYPE(obj)->tp_is_gc == NULL
-                || Py_TYPE(obj)->tp_is_gc(obj)));
-}
 
 /* Code built with Py_BUILD_CORE must include pycore_gc.h instead which
    defines a different _PyGC_FINALIZED() macro. */
diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
index 5c3d3cae235f47..edf965cb663967 100644
--- a/Include/internal/pycore_object.h
+++ b/Include/internal/pycore_object.h
@@ -100,6 +100,15 @@ _PyType_HasFeature(PyTypeObject *type, unsigned long feature) {
     return ((type->tp_flags & feature) != 0);
 }
 
+// Fast inlined version of PyObject_IS_GC()
+static inline int
+_PyObject_IS_GC(PyObject *obj)
+{
+    return (PyType_IS_GC(Py_TYPE(obj))
+            && (Py_TYPE(obj)->tp_is_gc == NULL
+                || Py_TYPE(obj)->tp_is_gc(obj)));
+}
+
 // Fast inlined version of PyType_IS_GC()
 #define _PyType_IS_GC(t) _PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC)
 
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index b472843d9df7f8..92f600311e0d15 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -19,6 +19,7 @@ Data members:
 #include "frameobject.h"
 #include "pycore_ceval.h"
 #include "pycore_initconfig.h"
+#include "pycore_object.h"
 #include "pycore_pathconfig.h"
 #include "pycore_pyerrors.h"
 #include "pycore_pylifecycle.h"

From 1c242b510a7d14fed0db1eed82a72aa2f7693bc5 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Wed, 15 Apr 2020 00:10:35 +0800
Subject: [PATCH 11/12] remove white space

---
 Doc/c-api/gcsupport.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index 22de9866cc0555..eee114c19d5904 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -65,7 +65,7 @@ Constructors for container types must conform to two rules:
 
    Returns non-zero if the object implements the garbage collector protocol,
    otherwise returns 0.
-   
+
    The object cannot be tracked by the garbage collector if this function returns 0.
 
 

From cffba905c5eae6c721387c413dfff5a0af6f8807 Mon Sep 17 00:00:00 2001
From: Hai Shi <shihai1992@gmail.com>
Date: Wed, 15 Apr 2020 00:12:52 +0800
Subject: [PATCH 12/12] update news

---
 Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst b/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst
index 6ec5e17b1f03f8..832b7f6e081d52 100644
--- a/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst	
+++ b/Misc/NEWS.d/next/C API/2020-04-11-06-12-44.bpo-40170.cmM9oK.rst	
@@ -1,2 +1,2 @@
 Convert :c:func:`PyObject_IS_GC` macro to a function to hide
-implementation details: the macro test an object have GC head or not.
+implementation details.