bpo-23867: Argument Clinic: inline parsing code for a single positional parameter. (GH-9689)

Python/getargs.c

@@ -612,6 +612,14 @@ convertitem(PyObject *arg, const char **p_format, va_list *p_va, int flags,
 
 /* Format an error message generated by convertsimple(). */
 
+void
+_PyArg_BadArgument(const char *fname, const char *expected, PyObject *arg)
+{
+    PyErr_Format(PyExc_TypeError, "%.200s() argument must be %.50s, not %.50s",
+                 fname, expected,
+                 arg == Py_None ? "None" : arg->ob_type->tp_name);
+}
+
 static const char *
 converterr(const char *expected, PyObject *arg, char *msgbuf, size_t bufsize)
 {