"Operator not supported" type error when using singleton constructs #1115

When using any of the singleton constructs (Bit, Int8ub, etc.) Pyright gives a false type error. This appears to be related #1018, but in this case its the type checker that thinks its a function when its actually been changed to variable.

The following struct:

BitParser = BitStruct(
    "is_bit" / Bit,
)

Gives this error:

Operator "/" not supported for types "Literal['is_bit']" and "() -> BitsInteger"

Potential solution

It might be simpler, especially for things like Bit, to just use a variable. For example,

@singleton
def Bit():
    """A 1-bit integer, must be enclosed in a Bitwise (eg. BitStruct)"""
    return BitsInteger(1)

is functionally identical to:

Bit = BitsInteger(1)
"""A 1-bit integer, must be enclosed in a Bitwise (eg. BitStruct)"""

This should cause fewer problems with type checking and make the code easier to read and maintain.