False Negative: Decorator signatures are unverified

[deckar01]

Steps to reproduce

def decorator(func):
    def wrap():
        return func('test')
    return wrap

@decorator
def simple():
    return 'test'

simple()

Current behavior

Pylint does not detect any errors.

Expected behavior

Pylint should detect that func is called with too many arguments.

pylint --version output

No config file found, using default configuration
pylint 1.6.4, 
astroid 1.4.8
Python 2.7.12 (default, Jun 28 2016, 06:57:42) [GCC]

Related issues

#259

[PCManticore]

Closing as duplicate.

[deckar01]

@PCManticore I took a closer look at it, and this is not actually checked with function composition either, so it is less related to #259 than I thought.

def dec(func):
    def wrap():
        return func('test')
    return wrap

def simple():
    return 'test'

hard = dec(simple)

hard()

Boiling it down further illustrates the difference.

def call(func):
    return func('test')

def simple():
    return 'test'

call(simple)

This code is guaranteed to error, but pylint doesn't report any errors.

[PCManticore]

This looks like an example of pylint-dev/astroid#177. This, combined with lack of flow control understanding across the inference, plus lack of understanding decorators, that stem from the first two points, results in the problems you are noticing. We know about it, it's not trivial to fix, but it's on our roadmap.