Omit no-member error if guarded behind if stmt

[cdce8p]

Type of Changes

	Type
✓	🐛 Bug fix

Description

Omit no-member errors if attribute / method access is guarded behind if statement.

This change doesn't implement control-flow logic. Instead I chose to check for an IF / IFExp node in the node parents and evaluate it. That doesn't solve all issue, especially not those with assert #4693, but I would never the less consider it an improvement.

As this is a larger change, I would like to target 2.10 for it.

Example

from datetime import datetime

value = "Hello World"
value.isoformat()  # [no-member]

if isinstance(value, datetime):
    value.isoformat()  # This is now fixed and doesn't emit 'no-member' anymore

--
Ref #1162 (not closed, but issue would be addressed)
Closes #1990
Closes #4168

[coveralls]

Coverage increased (+0.005%) to 92.225% when pulling b4cd3fd on cdce8p:fix-no-member into 24d03e9 on PyCQA:main.

[Pierre-Sassoulas]

I'm surprised that this does not break more functional tests. I think this is a nice way to remove some false positive using astroid inference.

[Pierre-Sassoulas]

That's pretty clever.