Struct types cannot be used with type hints as arguments to @ti.func

[AmesingFlank]

The following code works:

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

@ti.dataclass
class C:
    i: int

@ti.func
def f(c):
    return c.i

@ti.kernel
def k():
    c = C(i = 2)
    print(f(c))

k()

while this doesn't:

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

@ti.dataclass
class C:
    i: int

@ti.func
def f(c: C):
    return c.i

@ti.kernel
def k():
    c = C(i = 2)
    print(f(c))

k()

The only difference is the type hint: c: C
When the type hint is added, the following error is thrown:

  File "/Users/dunfanlu/Code/Taichi/taichi/python/taichi/lang/kernel_impl.py", line 341, in extract_arguments
    raise TaichiSyntaxError(
taichi.lang.exception.TaichiSyntaxError: Invalid type annotation (argument 0) of Taichi function: <taichi.lang.struct.StructType object at 0x10875e220>