github / github/codeql

LGTM.com - false positive - Python: Class may not be initialized properly as method is not called from its __init__ method

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false-positive
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Description

**Description of the false positive**

In python when a class inherits from multiple classes, if any of these classes does not have an `__init__` method, the `__init__` of the next class will be called. It seems this is not correctly considered, leading to a false positive for https://lgtm.com/query/rule:5990072/lang:python/

**URL to the alert on the project page on LGTM.com**

Two examples of this false positive are:

- https://lgtm.com/projects/g/omni-us/jsonargparse/snapshot/c57ebe0a019e3aa2809a974b727063cc99a2f894/files/jsonargparse/core.py?sort=name&dir=ASC&mode=heatmap#xd619df233fb609ab:1
- https://lgtm.com/projects/g/omni-us/jsonargparse/snapshot/c57ebe0a019e3aa2809a974b727063cc99a2f894/files/jsonargparse/core.py?sort=name&dir=ASC&mode=heatmap#xff377f03629481f2:1

Note that if the mentioned `__init__` methods wouldn't be called, then the code would not work at all. Anyway, it is easy to debug and see that these are correctly called.

I also reproduced this locally by running `codeql database create --language=python` and `codeql database analyze` for the query [MissingCallToInit.ql](https://lgtm.com/query/rule:5990072/lang:python/) and the code snippet below:

```python
import argparse

class ClassWithoutInit:
def some_method(self):
...

class ClassWithInit:
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)

class ActionsContainer(ClassWithoutInit, ClassWithInit, argparse._ActionsContainer):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)

class ArgumentGroup(ActionsContainer, argparse._ArgumentGroup):
new_attr: str = None

parser = argparse.ArgumentParser()
group = ArgumentGroup(parser, 'abc')
```

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