type is always PyUnicode_Type?

Author: erlend-aasland

Objects/unicodeobject.c

@@ -14671,14 +14671,16 @@ static PyObject *
 unicode_vectorcall(PyObject *type, PyObject *const *args,
                    size_t nargsf, PyObject *kwnames)
 {
+    assert(Py_Is(_PyType_CAST(type), &PyUnicode_Type));
+
     Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
     Py_ssize_t nkwargs = (kwnames) ? PyTuple_GET_SIZE(kwnames) : 0;
     if (nargs == 0 && nkwargs == 0) {
-        return unicode_new_impl(_PyType_CAST(type), NULL, NULL, NULL);
+        return unicode_get_empty();
     }
     PyObject *object = args[0];
     if (nargs == 1 && nkwargs == 0) {
-        return unicode_new_impl(_PyType_CAST(type), object, NULL, NULL);
+        return PyObject_Str(object);
     }
     if (nargs + nkwargs == 2) {
         const char *encoding;
@@ -14712,7 +14714,7 @@ unicode_vectorcall(PyObject *type, PyObject *const *args,
         else {
             return fallback_to_tp_call(type, nargs, nkwargs, args, kwnames);
         }
-        return unicode_new_impl(_PyType_CAST(type), object, encoding, errors);
+        return PyUnicode_FromEncodedObject(object, encoding, errors);
     }
     if (nargs + nkwargs == 3) {
         if (nkwargs == 1) {
@@ -14734,7 +14736,7 @@ unicode_vectorcall(PyObject *type, PyObject *const *args,
         if (errors == NULL) {
             return NULL;
         }
-        return unicode_new_impl(_PyType_CAST(type), object, encoding, errors);
+        return PyUnicode_FromEncodedObject(object, encoding, errors);
     }
     if (nargs > 3) {
         PyErr_Format(PyExc_TypeError,