Initialising nested @ti.dataclass throws error when argument name not explicitly given

[AmesingFlank]

Consider this code snippet

import taichi as ti
ti.init(ti.cpu)


@ti.dataclass
class X:
    i: int


@ti.dataclass
class Y:
    x: X


x = X(0)
y = Y(x)

it fails with

  File "test.py", line 17, in <module>
    y = Y(x)
  File "/Users/dunfanlu/Code/Taichi/taichi/python/taichi/lang/struct.py", line 677, in __call__
    d[name] = dtype(args[index])
  File "/Users/dunfanlu/Code/Taichi/taichi/python/taichi/lang/struct.py", line 687, in __call__
    struct = self.cast(entries)
  File "/Users/dunfanlu/Code/Taichi/taichi/python/taichi/lang/struct.py", line 717, in cast
    entries[k] = int(
TypeError: int() argument must be a string, a bytes-like object or a number, not 'Struct'

But if the final line y = Y(x) is replaced with y = Y(x=x), then it works.