remove FUNCFLAG_VARIADIC

Author: lawrence-danna-apple

Doc/library/ctypes.rst

@@ -1579,13 +1579,6 @@ They are instances of a private class:
       value usable as argument (integer, string, ctypes instance).  This allows
       defining adapters that can adapt custom objects as function parameters.
 
-   .. attribute:: variadic
-
-      Assign a boolean to specify that the function takes a variable number of
-      arguments.   This does not matter on most platforms, but for Apple arm64
-      platforms variadic functions have a different calling convention than
-      normal functions.
-
    .. attribute:: errcheck
 
       Assign a Python function or another callable to this attribute. The

Lib/test/test_bytes.py

@@ -1034,7 +1034,6 @@ def test_from_format(self):
             c_char_p)
 
         PyBytes_FromFormat = pythonapi.PyBytes_FromFormat
-        PyBytes_FromFormat.variadic = True
         PyBytes_FromFormat.argtypes = (c_char_p,)
         PyBytes_FromFormat.restype = py_object
 

Lib/test/test_unicode.py

@@ -2516,7 +2516,6 @@ def test_from_format(self):
         name = "PyUnicode_FromFormat"
         _PyUnicode_FromFormat = getattr(pythonapi, name)
         _PyUnicode_FromFormat.argtypes = (c_char_p,)
-        _PyUnicode_FromFormat.variadic = True
         _PyUnicode_FromFormat.restype = py_object
 
         def PyUnicode_FromFormat(format, *args):

Modules/_ctypes/_ctypes.c

@@ -3320,35 +3320,6 @@ PyCFuncPtr_get_restype(PyCFuncPtrObject *self, void *Py_UNUSED(ignored))
     }
 }
 
-static int
-PyCFuncPtr_set_variadic(PyCFuncPtrObject *self, PyObject *ob, void *Py_UNUSED(ignored))
-{
-    StgDictObject *dict = PyObject_stgdict((PyObject *)self);
-    assert(dict);
-    int r = PyObject_IsTrue(ob);
-    if (r == 1) {
-        dict->flags |= FUNCFLAG_VARIADIC;
-        return 0;
-    } else if (r == 0) {
-        dict->flags &= ~FUNCFLAG_VARIADIC;
-        return 0;
-    } else {
-        return -1;
-    }
-}
-
-static PyObject *
-PyCFuncPtr_get_variadic(PyCFuncPtrObject *self, void *Py_UNUSED(ignored))
-{
-    StgDictObject *dict = PyObject_stgdict((PyObject *)self);
-    assert(dict); /* Cannot be NULL for PyCFuncPtrObject instances */
-    if (dict->flags & FUNCFLAG_VARIADIC)
-        Py_RETURN_TRUE;
-    else
-        Py_RETURN_FALSE;
-}
-
-
 static int
 PyCFuncPtr_set_argtypes(PyCFuncPtrObject *self, PyObject *ob, void *Py_UNUSED(ignored))
 {
@@ -3394,8 +3365,6 @@ static PyGetSetDef PyCFuncPtr_getsets[] = {
     { "argtypes", (getter)PyCFuncPtr_get_argtypes,
       (setter)PyCFuncPtr_set_argtypes,
       "specify the argument types", NULL },
-    { "variadic", (getter)PyCFuncPtr_get_variadic, (setter)PyCFuncPtr_set_variadic,
-      "specify if function takes variable number of arguments", NULL },
     { NULL, NULL }
 };
 
@@ -5870,7 +5839,6 @@ PyInit__ctypes(void)
     PyModule_AddObject(m, "FUNCFLAG_USE_ERRNO", PyLong_FromLong(FUNCFLAG_USE_ERRNO));
     PyModule_AddObject(m, "FUNCFLAG_USE_LASTERROR", PyLong_FromLong(FUNCFLAG_USE_LASTERROR));
     PyModule_AddObject(m, "FUNCFLAG_PYTHONAPI", PyLong_FromLong(FUNCFLAG_PYTHONAPI));
-    PyModule_AddObject(m, "FUNCFLAG_VARIADIC", PyLong_FromLong(FUNCFLAG_VARIADIC));
     PyModule_AddStringConstant(m, "__version__", "1.1.0");
 
     PyModule_AddObject(m, "_memmove_addr", PyLong_FromVoidPtr(memmove));

Modules/_ctypes/callproc.c

@@ -847,11 +847,12 @@ static int _call_function_pointer(int flags,
 #      define HAVE_FFI_PREP_CIF_VAR_RUNTIME false
 #   endif
 
-    /* Everyone SHOULD set f.variadic=True on variadic function pointers, but
-     * lots of existing code will not.  If there's at least one arg and more
-     * args are passed than are defined in the prototype, then it must be a
-     * variadic function. */
-    bool is_variadic = (flags & FUNCFLAG_VARIADIC) || (argtypecount != 0 && argcount > argtypecount);
+    /* Even on Apple-arm64 the calling convention for variadic functions conincides
+     * with the standard calling convention in the case that the function called
+     * only with its fixed arguments.   Thus, we do not need a special flag to be
+     * set on variadic functions.   We treat a function as variadic if it is called
+     * with a nonzero number of variadic arguments */
+    bool is_variadic = (argtypecount != 0 && argcount > argtypecount);
     (void) is_variadic;
 
 #if defined(__APPLE__) && defined(__arm64__)

Modules/_ctypes/ctypes.h

@@ -285,7 +285,6 @@ PyObject *_ctypes_callproc(PPROC pProc,
 #define FUNCFLAG_PYTHONAPI 0x4
 #define FUNCFLAG_USE_ERRNO 0x8
 #define FUNCFLAG_USE_LASTERROR 0x10
-#define FUNCFLAG_VARIADIC 0x20
 
 #define TYPEFLAG_ISPOINTER 0x100
 #define TYPEFLAG_HASPOINTER 0x200