Code Inspector possibly misuses type hints


I'm currently using PyCharm for a web project with Django, and I recently ran into an inspector problem I'm not sure to understand: I use type hints for most of my functions, and it seems that a return type hint broke the inspector.

Here is the function (without its parameter, as there is quite a few optionnal ones) def line. Its return type may be a list or a dict, as it is the result of json.loads().

def get_from(...) -> Union[dict, list]:

And here is the code snippet that uses it and where it broke:

darksky_results = get_from(request_url, 'DarkSky')
hourly_forecasts = darksky_results['hourly']['data']

More exactly, the inspector warns me that 'data' is of an unexpected type (even if, in case of a dict return type, it is absolutely possible to have another dict at the 'hourly' key). Seeing the complete warning just below, it seems like the inspector is sure darksky_results['hourly'] is some kind of list.

Unexpected type(s): (str) Possible types: (int) (slice) 
Inspection info: This inspection detects type errors in function call expressions.
Due to dynamic dispatch and duck typing, this is possible in a limited but useful number of cases.
Types of function parameters can be specified in docstrings or in Python 3 function annotations.

This problem doesn't really break my code (it still runs perfectly fine), but it bugs me a bit and I didn't find how to correct it (except by stopping using annotations, which I'd prefer not to).

Thanks for your help

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Hi, it's possible the issue is related to some other part of your code. I would suggest to submit a bug report to with a minimal code/project sample, so we could investigate.

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I will do this. I didn't know of at the time I wrote my initial comment, but it seems like the best platform for this kind of thing.

Thanks for the redirection.


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