gh-104922: Make PY_SSIZE_T_CLEAN not mandatory

Doc/c-api/arg.rst

@@ -70,9 +70,10 @@ There are three ways strings and buffers can be converted to C:
 
 .. 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
+   From Python 3.10 to 3.12, the macro :c:macro:`PY_SSIZE_T_CLEAN` had to
+   be defined before including :file:`Python.h` to use all ``#`` variants of
+   formats (``s#``, ``y#``, etc.).
+   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.
 

Doc/c-api/intro.rst

@@ -48,7 +48,7 @@ Include Files
 All function, type and macro definitions needed to use the Python/C API are
 included in your code by the following line::
 
-   #define PY_SSIZE_T_CLEAN
+   #define PY_SSIZE_T_CLEAN  /* needed until Python 3.12 */
    #include <Python.h>
 
 This implies inclusion of the following standard headers: ``<stdio.h>``,

Doc/extending/extending.rst

@@ -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  /* needed until Python 3.12 */
    #include <Python.h>
 
 ::

Doc/whatsnew/3.13.rst

@@ -219,6 +219,10 @@ C API Changes
 New Features
 ------------
 
+* You can now use the ``#``-specifier in :ref:`format codes <arg-parsing>`
+  without ``#define PY_SSIZE_T_CLEAN`` before ``#include <Python.h>``.
+  (Contributed by Inada Naoki in :gh:`104922`.)
+
 Porting to Python 3.13
 ----------------------
 

Include/abstract.h

@@ -135,10 +135,8 @@ extern "C" {
    This function always succeeds. */
 
 
-#ifdef PY_SSIZE_T_CLEAN
-#  define PyObject_CallFunction _PyObject_CallFunction_SizeT
-#  define PyObject_CallMethod _PyObject_CallMethod_SizeT
-#endif
+#define PyObject_CallFunction _PyObject_CallFunction_SizeT
+#define PyObject_CallMethod _PyObject_CallMethod_SizeT
 
 
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03090000
@@ -195,15 +193,6 @@ 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

@@ -2,19 +2,19 @@
 #  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(
+    PyObject **small_stack,
+    Py_ssize_t small_stack_len,
+    const char *format,
+    va_list va,
+    Py_ssize_t *p_nargs);
+
 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,
@@ -43,13 +43,6 @@ PyAPI_FUNC(int) _PyArg_CheckPositional(const char *, Py_ssize_t,
     ((!_Py_ANY_VARARGS(max) && (min) <= (nargs) && (nargs) <= (max)) \
      || _PyArg_CheckPositional((funcname), (nargs), (min), (max)))
 
-PyAPI_FUNC(PyObject **) _Py_VaBuildStack(
-    PyObject **small_stack,
-    Py_ssize_t small_stack_len,
-    const char *format,
-    va_list va,
-    Py_ssize_t *p_nargs);
-
 typedef struct _PyArg_Parser {
     int initialized;
     const char *format;
@@ -63,13 +56,6 @@ 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

@@ -9,20 +9,19 @@ 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
+/* Since Python 3.13, each functions treats #-specifier to mean Py_ssize_t
+ * regardless PY_SSIZE_T_CLEAN is defined,
+ */
 #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
+#if !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 *,
@@ -34,9 +33,6 @@ PyAPI_FUNC(int) PyArg_VaParseTupleAndKeywords(PyObject *, PyObject *,
 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.

Misc/NEWS.d/next/C API/2023-05-25-17-30-43.gh-issue-104922.V6nibW.rst

@@ -0,0 +1,2 @@
+``PY_SSIZE_T_CLEAN`` is no longer required to use '#' specifier in APIs like
+:c:func:`PyArg_ParseTuple` and :c:func:`Py_BuildValue`.

Misc/stable_abi.toml

@@ -383,16 +383,21 @@
 
 [function.PyArg_Parse]
     added = '3.2'
+    abi_only = true
 [function.PyArg_ParseTuple]
     added = '3.2'
+    abi_only = true
 [function.PyArg_ParseTupleAndKeywords]
     added = '3.2'
+    abi_only = true
 [function.PyArg_UnpackTuple]
     added = '3.2'
 [function.PyArg_VaParse]
     added = '3.2'
+    abi_only = true
 [function.PyArg_VaParseTupleAndKeywords]
     added = '3.2'
+    abi_only = true
 [function.PyArg_ValidateKeywordArguments]
     added = '3.2'
 [data.PyBaseObject_Type]
@@ -1132,10 +1137,12 @@
     added = '3.2'
 [function.PyObject_CallFunction]
     added = '3.2'
+    abi_only = true
 [function.PyObject_CallFunctionObjArgs]
     added = '3.2'
 [function.PyObject_CallMethod]
     added = '3.2'
+    abi_only = true
 [function.PyObject_CallMethodObjArgs]
     added = '3.2'
 [function.PyObject_CallObject]
@@ -1595,6 +1602,7 @@
     added = '3.2'
 [function.Py_BuildValue]
     added = '3.2'
+    abi_only = true
 [function.Py_CompileString]
     added = '3.2'
 [function.Py_DecRef]
@@ -1661,6 +1669,7 @@
     added = '3.2'
 [function.Py_VaBuildValue]
     added = '3.2'
+    abi_only = true
 
 [function._PyErr_BadInternalCall]
     added = '3.2'

Objects/call.c

@@ -572,8 +572,9 @@ _PyObject_CallFunctionVa(PyThreadState *tstate, PyObject *callable,
     return result;
 }
 
-
-PyObject *
+// Export for the stable ABI
+#undef PyObject_CallFunction
+PyAPI_FUNC(PyObject *)
 PyObject_CallFunction(PyObject *callable, const char *format, ...)
 {
     va_list va;
@@ -634,7 +635,9 @@ callmethod(PyThreadState *tstate, PyObject* callable, const char *format, va_lis
     return _PyObject_CallFunctionVa(tstate, callable, format, va, is_size_t);
 }
 
-PyObject *
+// Export for the stable ABI
+#undef PyObject_CallMethod
+PyAPI_FUNC(PyObject *)
 PyObject_CallMethod(PyObject *obj, const char *name, const char *format, ...)
 {
     PyThreadState *tstate = _PyThreadState_GET();
@@ -724,7 +727,7 @@ _PyObject_CallMethodId(PyObject *obj, _Py_Identifier *name,
 
     va_list va;
     va_start(va, format);
-    PyObject *retval = callmethod(tstate, callable, format, va, 0);
+    PyObject *retval = callmethod(tstate, callable, format, va, 1);
     va_end(va);
 
     Py_DECREF(callable);
@@ -767,30 +770,6 @@ _PyObject_CallMethod_SizeT(PyObject *obj, const char *name,
 }
 
 
-PyObject *
-_PyObject_CallMethodId_SizeT(PyObject *obj, _Py_Identifier *name,
-                             const char *format, ...)
-{
-    PyThreadState *tstate = _PyThreadState_GET();
-    if (obj == NULL || name == NULL) {
-        return null_error(tstate);
-    }
-
-    PyObject *callable = _PyObject_GetAttrId(obj, name);
-    if (callable == NULL) {
-        return NULL;
-    }
-
-    va_list va;
-    va_start(va, format);
-    PyObject *retval = callmethod(tstate, callable, format, va, 1);
-    va_end(va);
-
-    Py_DECREF(callable);
-    return retval;
-}
-
-
 /* --- Call with "..." arguments ---------------------------------- */
 
 static PyObject *