gh-104922: Make PY_SSIZE_T_CLEAN not mandatory again (#105051)

Author: methane

Doc/c-api/arg.rst

@@ -27,9 +27,18 @@ unit; the entry in (round) parentheses is the Python object type that matches
 the format unit; and the entry in [square] brackets is the type of the C
 variable(s) whose address should be passed.
 
+.. _arg-parsing-string-and-buffers:
+
 Strings and buffers
 -------------------
 
+.. note::
+
+   On Python 3.12 and older, the macro :c:macro:`!PY_SSIZE_T_CLEAN` must be
+   defined before including :file:`Python.h` to use all ``#`` variants of
+   formats (``s#``, ``y#``, etc.) explained below.
+   This is not necessary on Python 3.13 and later.
+
 These formats allow accessing an object as a contiguous chunk of memory.
 You don't have to provide raw storage for the returned unicode or bytes
 area.
@@ -68,15 +77,6 @@ There are three ways strings and buffers can be converted to C:
    whether the input object is immutable (e.g. whether it would honor a request
    for a writable buffer, or whether another thread can mutate the data).
 
-.. note::
-
-   For all ``#`` variants of formats (``s#``, ``y#``, etc.), the macro
-   :c:macro:`PY_SSIZE_T_CLEAN` must be defined before including
-   :file:`Python.h`. On Python 3.9 and older, the type of the length argument
-   is :c:type:`Py_ssize_t` if the :c:macro:`PY_SSIZE_T_CLEAN` macro is defined,
-   or int otherwise.
-
-
 ``s`` (:class:`str`) [const char \*]
    Convert a Unicode object to a C pointer to a character string.
    A pointer to an existing string is stored in the character pointer

Doc/extending/extending.rst

@@ -70,7 +70,7 @@ the module and a copyright notice if you like).
    headers are included.
 
    It is recommended to always define ``PY_SSIZE_T_CLEAN`` before including
-   ``Python.h``.  See :ref:`parsetuple` for a description of this macro.
+   ``Python.h``.  See :ref:`arg-parsing-string-and-buffers` for a description of this macro.
 
 All user-visible symbols defined by :file:`Python.h` have a prefix of ``Py`` or
 ``PY``, except those defined in standard header files. For convenience, and
@@ -649,7 +649,7 @@ Note that any Python object references which are provided to the caller are
 
 Some example calls::
 
-   #define PY_SSIZE_T_CLEAN  /* Make "s#" use Py_ssize_t rather than int. */
+   #define PY_SSIZE_T_CLEAN
    #include <Python.h>
 
 ::
@@ -745,7 +745,7 @@ it returns false and raises an appropriate exception.
 Here is an example module which uses keywords, based on an example by Geoff
 Philbrick ([email protected])::
 
-   #define PY_SSIZE_T_CLEAN  /* Make "s#" use Py_ssize_t rather than int. */
+   #define PY_SSIZE_T_CLEAN
    #include <Python.h>
 
    static PyObject *

Doc/whatsnew/3.13.rst

@@ -292,6 +292,13 @@ C API Changes
 New Features
 ------------
 
+* You no longer have to define the ``PY_SSIZE_T_CLEAN`` macro before including
+  :file:`Python.h` when using ``#`` formats in
+  :ref:`format codes <arg-parsing-string-and-buffers>`.
+  APIs accepting the format codes always use ``Py_ssize_t`` for ``#`` formats.
+  (Contributed by Inada Naoki in :gh:`104922`.)
+
+
 Porting to Python 3.13
 ----------------------
 

Include/abstract.h

@@ -135,12 +135,6 @@ extern "C" {
    This function always succeeds. */
 
 
-#ifdef PY_SSIZE_T_CLEAN
-#  define PyObject_CallFunction _PyObject_CallFunction_SizeT
-#  define PyObject_CallMethod _PyObject_CallMethod_SizeT
-#endif
-
-
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03090000
 /* Call a callable Python object without any arguments */
 PyAPI_FUNC(PyObject *) PyObject_CallNoArgs(PyObject *func);
@@ -195,15 +189,6 @@ PyAPI_FUNC(PyObject *) PyObject_CallMethod(PyObject *obj,
                                            const char *name,
                                            const char *format, ...);
 
-PyAPI_FUNC(PyObject *) _PyObject_CallFunction_SizeT(PyObject *callable,
-                                                    const char *format,
-                                                    ...);
-
-PyAPI_FUNC(PyObject *) _PyObject_CallMethod_SizeT(PyObject *obj,
-                                                  const char *name,
-                                                  const char *format,
-                                                  ...);
-
 /* Call a callable Python object 'callable' with a variable number of C
    arguments. The C arguments are provided as PyObject* values, terminated
    by a NULL.

Include/cpython/abstract.h

@@ -4,10 +4,6 @@
 
 /* === Object Protocol ================================================== */
 
-#ifdef PY_SSIZE_T_CLEAN
-#  define _PyObject_CallMethodId _PyObject_CallMethodId_SizeT
-#endif
-
 /* Convert keyword arguments from the FASTCALL (stack: C array, kwnames: tuple)
    format to a Python dictionary ("kwargs" dict).
 
@@ -113,11 +109,6 @@ PyAPI_FUNC(PyObject *) _PyObject_CallMethodId(PyObject *obj,
                                               _Py_Identifier *name,
                                               const char *format, ...);
 
-PyAPI_FUNC(PyObject *) _PyObject_CallMethodId_SizeT(PyObject *obj,
-                                                    _Py_Identifier *name,
-                                                    const char *format,
-                                                    ...);
-
 PyAPI_FUNC(PyObject *) _PyObject_CallMethodIdObjArgs(
     PyObject *obj,
     _Py_Identifier *name,

Include/cpython/modsupport.h

@@ -2,20 +2,6 @@
 #  error "this header file must not be included directly"
 #endif
 
-/* If PY_SSIZE_T_CLEAN is defined, each functions treats #-specifier
-   to mean Py_ssize_t */
-#ifdef PY_SSIZE_T_CLEAN
-#define _Py_VaBuildStack                _Py_VaBuildStack_SizeT
-#else
-PyAPI_FUNC(PyObject *) _Py_VaBuildValue_SizeT(const char *, va_list);
-PyAPI_FUNC(PyObject **) _Py_VaBuildStack_SizeT(
-    PyObject **small_stack,
-    Py_ssize_t small_stack_len,
-    const char *format,
-    va_list va,
-    Py_ssize_t *p_nargs);
-#endif
-
 PyAPI_FUNC(int) _PyArg_UnpackStack(
     PyObject *const *args,
     Py_ssize_t nargs,
@@ -63,13 +49,6 @@ typedef struct _PyArg_Parser {
     struct _PyArg_Parser *next;
 } _PyArg_Parser;
 
-#ifdef PY_SSIZE_T_CLEAN
-#define _PyArg_ParseTupleAndKeywordsFast  _PyArg_ParseTupleAndKeywordsFast_SizeT
-#define _PyArg_ParseStack  _PyArg_ParseStack_SizeT
-#define _PyArg_ParseStackAndKeywords  _PyArg_ParseStackAndKeywords_SizeT
-#define _PyArg_VaParseTupleAndKeywordsFast  _PyArg_VaParseTupleAndKeywordsFast_SizeT
-#endif
-
 PyAPI_FUNC(int) _PyArg_ParseTupleAndKeywordsFast(PyObject *, PyObject *,
                                                  struct _PyArg_Parser *, ...);
 PyAPI_FUNC(int) _PyArg_ParseStack(

Include/modsupport.h

@@ -9,34 +9,17 @@ extern "C" {
 
 #include <stdarg.h>               // va_list
 
-/* If PY_SSIZE_T_CLEAN is defined, each functions treats #-specifier
-   to mean Py_ssize_t */
-#ifdef PY_SSIZE_T_CLEAN
-#define PyArg_Parse                     _PyArg_Parse_SizeT
-#define PyArg_ParseTuple                _PyArg_ParseTuple_SizeT
-#define PyArg_ParseTupleAndKeywords     _PyArg_ParseTupleAndKeywords_SizeT
-#define PyArg_VaParse                   _PyArg_VaParse_SizeT
-#define PyArg_VaParseTupleAndKeywords   _PyArg_VaParseTupleAndKeywords_SizeT
-#define Py_BuildValue                   _Py_BuildValue_SizeT
-#define Py_VaBuildValue                 _Py_VaBuildValue_SizeT
-#endif
-
-/* Due to a glitch in 3.2, the _SizeT versions weren't exported from the DLL. */
-#if !defined(PY_SSIZE_T_CLEAN) || !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
 PyAPI_FUNC(int) PyArg_Parse(PyObject *, const char *, ...);
 PyAPI_FUNC(int) PyArg_ParseTuple(PyObject *, const char *, ...);
 PyAPI_FUNC(int) PyArg_ParseTupleAndKeywords(PyObject *, PyObject *,
-                                                  const char *, char **, ...);
+                                            const char *, char **, ...);
 PyAPI_FUNC(int) PyArg_VaParse(PyObject *, const char *, va_list);
 PyAPI_FUNC(int) PyArg_VaParseTupleAndKeywords(PyObject *, PyObject *,
-                                                  const char *, char **, va_list);
-#endif
+                                              const char *, char **, va_list);
+
 PyAPI_FUNC(int) PyArg_ValidateKeywordArguments(PyObject *);
 PyAPI_FUNC(int) PyArg_UnpackTuple(PyObject *, const char *, Py_ssize_t, Py_ssize_t, ...);
 PyAPI_FUNC(PyObject *) Py_BuildValue(const char *, ...);
-PyAPI_FUNC(PyObject *) _Py_BuildValue_SizeT(const char *, ...);
-
-
 PyAPI_FUNC(PyObject *) Py_VaBuildValue(const char *, va_list);
 
 // Add an attribute with name 'name' and value 'obj' to the module 'mod.

Lib/test/test_capi/test_getargs.py

@@ -901,23 +901,6 @@ def test_s_hash(self):
         self.assertRaises(TypeError, getargs_s_hash, memoryview(b'memoryview'))
         self.assertRaises(TypeError, getargs_s_hash, None)
 
-    def test_s_hash_int(self):
-        # "s#" without PY_SSIZE_T_CLEAN defined.
-        from _testcapi import getargs_s_hash_int
-        from _testcapi import getargs_s_hash_int2
-        buf = bytearray([1, 2])
-        self.assertRaises(SystemError, getargs_s_hash_int, buf, "abc")
-        self.assertRaises(SystemError, getargs_s_hash_int, buf, x=42)
-        self.assertRaises(SystemError, getargs_s_hash_int, buf, x="abc")
-        self.assertRaises(SystemError, getargs_s_hash_int2, buf, ("abc",))
-        self.assertRaises(SystemError, getargs_s_hash_int2, buf, x=42)
-        self.assertRaises(SystemError, getargs_s_hash_int2, buf, x="abc")
-        buf.append(3)  # still mutable -- not locked by a buffer export
-        # getargs_s_hash_int(buf) may not raise SystemError because skipitem()
-        # is not called. But it is an implementation detail.
-        # getargs_s_hash_int(buf)
-        # getargs_s_hash_int2(buf)
-
     def test_z(self):
         from _testcapi import getargs_z
         self.assertEqual(getargs_z('abc\xe9'), b'abc\xc3\xa9')

Misc/NEWS.d/next/C API/2023-05-29-16-09-27.gh-issue-104922.L23qaU.rst

@@ -0,0 +1,3 @@
+``PY_SSIZE_T_CLEAN`` is no longer required to use ``'#'`` formats in APIs
+like :c:func:`PyArg_ParseTuple` and :c:func:`Py_BuildValue`. They uses
+``Py_ssize_t`` for ``'#'`` regardless ``PY_SSIZE_T_CLEAN``.

Modules/_testcapi/getargs.c

@@ -816,44 +816,6 @@ test_s_code(PyObject *self, PyObject *Py_UNUSED(ignored))
     Py_RETURN_NONE;
 }
 
-#undef PyArg_ParseTupleAndKeywords
-PyAPI_FUNC(int) PyArg_ParseTupleAndKeywords(PyObject *, PyObject *,
-                                            const char *, char **, ...);
-
-static PyObject *
-getargs_s_hash_int(PyObject *self, PyObject *args, PyObject *kwargs)
-{
-    static char *keywords[] = {"", "", "x", NULL};
-    Py_buffer buf = {NULL};
-    const char *s;
-    int len;
-    int i = 0;
-    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "w*|s#i", keywords,
-                                     &buf, &s, &len, &i))
-    {
-        return NULL;
-    }
-    PyBuffer_Release(&buf);
-    Py_RETURN_NONE;
-}
-
-static PyObject *
-getargs_s_hash_int2(PyObject *self, PyObject *args, PyObject *kwargs)
-{
-    static char *keywords[] = {"", "", "x", NULL};
-    Py_buffer buf = {NULL};
-    const char *s;
-    int len;
-    int i = 0;
-    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "w*|(s#)i", keywords,
-                                     &buf, &s, &len, &i))
-    {
-        return NULL;
-    }
-    PyBuffer_Release(&buf);
-    Py_RETURN_NONE;
-}
-
 static PyObject *
 gh_99240_clear_args(PyObject *self, PyObject *args)
 {
@@ -906,8 +868,6 @@ static PyMethodDef test_methods[] = {
     {"getargs_positional_only_and_keywords", _PyCFunction_CAST(getargs_positional_only_and_keywords), METH_VARARGS|METH_KEYWORDS},
     {"getargs_s",               getargs_s,                       METH_VARARGS},
     {"getargs_s_hash",          getargs_s_hash,                  METH_VARARGS},
-    {"getargs_s_hash_int", _PyCFunction_CAST(getargs_s_hash_int), METH_VARARGS|METH_KEYWORDS},
-    {"getargs_s_hash_int2", _PyCFunction_CAST(getargs_s_hash_int2), METH_VARARGS|METH_KEYWORDS},
     {"getargs_s_star",          getargs_s_star,                  METH_VARARGS},
     {"getargs_tuple",           getargs_tuple,                   METH_VARARGS},
     {"getargs_u",               getargs_u,                       METH_VARARGS},