MyPy can't detect default arguments for data types

[ArneBachmann]

I have this code which compiles and runs fine:

data TimeInterval(fromHour:float, toHour:float, weekFactor:float = 7./7.): pass

Is compiled to Python code:

class TimeInterval(_coconut_NamedTuple("TimeInterval", [("fromHour", 'float'), ("toHour", 'float'), ("weekFactor", 'float')]), _coconut.object):
    __slots__ = ()
    __ne__ = _coconut.object.__ne__
    def __new__(_cls, fromHour, toHour, weekFactor=7. / 7.):
        return _coconut.tuple.__new__(_cls, (fromHour, toHour, weekFactor))
    pass

And it seems that the third argument is still optional.
When I run with --mypy, however, there is an issue raised:

untitled.py:31: error: Missing positional argument "weekFactor" in call to "TimeInterval"
untitled.py:38: error: Too few arguments for "TimeInterval"

where line 31 refers to a function definition providing only the required arguments for the default value:

def b(date, coordinates, window, timeInterval=TimeInterval(fromHour=0., toHour=23.99),  # type: TimeInterval
     obstacles=[], minute_interval=5  # type: int
    ):

and line 38 refers to a manual object creation (testing purposes):

x = TimeInterval(1, 2)

which works fine without --mypy.
Not sure if this is a mypy error or has to do with Coconut. It's hard to report mypy errors with compiled Coconut code, as it's not runnable via python compiled.py and requires lots of Coconut libraries..

[ArneBachmann]

untitled.coco.txt

[evhub]

@ArneBachmann Yeah, this is a known issue. MyPy can't handle the redefinition of __new__, so it doesn't know that the argument has been made optional. I'll keep this open and maybe try to ping the MyPy people about it.

[iamrecursion]

If I'm recalling correctly this is an issue specific to the redefinition of __new__ for NamedTuple instances. It's been a while since I've futzed around with MyPy however. It's possibly related to this python/mypy#3307.