From ef5c615f5ae72c4f6979159c94da46afefbfab9a Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Wed, 8 Apr 2020 01:13:53 +0200
Subject: [PATCH] bpo-40170: Convert PyObject_CheckBuffer() macro to a function
 (GH-19376)

Convert PyObject_CheckBuffer() macro to a function to hide
implementation details: the macro accessed directly the
PyTypeObject.tp_as_buffer member.
---
 Include/cpython/abstract.h                             |  4 +---
 .../C API/2020-04-05-00-02-13.bpo-40170.IFsGZ-.rst     |  3 +++
 Objects/abstract.c                                     | 10 ++++++++++
 3 files changed, 14 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/C API/2020-04-05-00-02-13.bpo-40170.IFsGZ-.rst

diff --git a/Include/cpython/abstract.h b/Include/cpython/abstract.h
index 9d23c8c11be..3f834ff727e 100644
--- a/Include/cpython/abstract.h
+++ b/Include/cpython/abstract.h
@@ -264,9 +264,7 @@ PyAPI_FUNC(Py_ssize_t) PyObject_LengthHint(PyObject *o, Py_ssize_t);
 /* === New Buffer API ============================================ */
 
 /* Return 1 if the getbuffer function is available, otherwise return 0. */
-#define PyObject_CheckBuffer(obj) \
-    ((Py_TYPE(obj)->tp_as_buffer != NULL) &&  \
-     (Py_TYPE(obj)->tp_as_buffer->bf_getbuffer != NULL))
+PyAPI_FUNC(int) PyObject_CheckBuffer(PyObject *obj);
 
 /* This is a C-API version of the getbuffer function call.  It checks
    to make sure object has the required function pointer and issues the
diff --git a/Misc/NEWS.d/next/C API/2020-04-05-00-02-13.bpo-40170.IFsGZ-.rst b/Misc/NEWS.d/next/C API/2020-04-05-00-02-13.bpo-40170.IFsGZ-.rst
new file mode 100644
index 00000000000..fb378faa90c
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2020-04-05-00-02-13.bpo-40170.IFsGZ-.rst	
@@ -0,0 +1,3 @@
+Convert :c:func:`PyObject_CheckBuffer` macro to a function to hide
+implementation details: the macro accessed directly the
+:c:member:`PyTypeObject.tp_as_buffer` member.
diff --git a/Objects/abstract.c b/Objects/abstract.c
index e975edd7c5b..49a38d8f6e2 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -277,6 +277,16 @@ PyObject_DelItemString(PyObject *o, const char *key)
     return ret;
 }
 
+
+/* Return 1 if the getbuffer function is available, otherwise return 0. */
+int
+PyObject_CheckBuffer(PyObject *obj)
+{
+    PyBufferProcs *tp_as_buffer = Py_TYPE(obj)->tp_as_buffer;
+    return (tp_as_buffer != NULL && tp_as_buffer->bf_getbuffer != NULL);
+}
+
+
 /* We release the buffer right after use of this function which could
    cause issues later on.  Don't use these functions in new code.
  */