gh-98410: move getbufferproc and releasebufferproc to buffer.h (#31158)

This adds them to the Limited API.

Doc/data/stable_abi.dat

@@ -865,6 +865,7 @@ type,descrsetfunc,3.2,,
 type,destructor,3.2,,
 type,getattrfunc,3.2,,
 type,getattrofunc,3.2,,
+type,getbufferproc,3.12,,
 type,getiterfunc,3.2,,
 type,getter,3.2,,
 type,hashfunc,3.2,,
@@ -875,6 +876,7 @@ type,lenfunc,3.2,,
 type,newfunc,3.2,,
 type,objobjargproc,3.2,,
 type,objobjproc,3.2,,
+type,releasebufferproc,3.12,,
 type,reprfunc,3.2,,
 type,richcmpfunc,3.2,,
 type,setattrfunc,3.2,,

Include/cpython/object.h

@@ -51,10 +51,6 @@ typedef struct _Py_Identifier {
 
 #endif  /* NEEDS_PY_IDENTIFIER */
 
-typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
-typedef void (*releasebufferproc)(PyObject *, Py_buffer *);
-
-
 typedef struct {
     /* Number implementations must check *both*
        arguments for proper type and implement the necessary conversions

Include/pybuffer.h

@@ -32,6 +32,9 @@ typedef struct {
     void *internal;
 } Py_buffer;
 
+typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
+typedef void (*releasebufferproc)(PyObject *, Py_buffer *);
+
 /* Return 1 if the getbuffer function is available, otherwise return 0. */
 PyAPI_FUNC(int) PyObject_CheckBuffer(PyObject *obj);
 

Misc/NEWS.d/next/C API/2022-10-25-17-50-43.gh-issue-98410.NSXYfm.rst

@@ -0,0 +1 @@
+Add ``getbufferproc`` and ``releasebufferproc`` to the stable API.

Misc/stable_abi.toml

@@ -2299,3 +2299,7 @@
     added = '3.12'
 [macro.PY_VECTORCALL_ARGUMENTS_OFFSET]
     added = '3.12'
+[typedef.getbufferproc]
+    added = '3.12'
+[typedef.releasebufferproc]
+    added = '3.12'