False negative: no-member in conditional branch about pylint HOT 2 OPEN

Thanks for the response! Your suggested patch does indeed fix the more complex conditional case, though the simple case still produces a false negative. I'll see if I can create a test from the more complex case, and if so then I'll submit a PR.

from pylint.

This change was made in #4764 to address false positives where the if guards are performing a type-narrowing function.

There are two follow-ups I see immediately from your report, though.

1. there's a better way of doing this now that we have constraints in astroid. See pylint-dev/astroid#1189. I think your report should stand as the feature request for that.

2. Regarding:

This can also happen for more complex conditionals, where it's not clear whether or not the branch is reachable.

We might be able to solve that by leveraging a recent feature:

diff --git a/pylint/checkers/typecheck.py b/pylint/checkers/typecheck.py
index 9c73fee82..e559a8bdd 100644
--- a/pylint/checkers/typecheck.py
+++ b/pylint/checkers/typecheck.py
@@ -513,7 +513,7 @@ def _emit_no_member(
     parent: nodes.NodeNG = node.parent
     while parent != scope:
         if isinstance(parent, (nodes.If, nodes.IfExp)):
-            inferred = safe_infer(parent.test)
+            inferred = safe_infer(parent.test, compare_constants=True)
             if (  # pylint: disable=too-many-boolean-expressions
                 isinstance(inferred, nodes.Const)
                 and inferred.bool_value() is False

Would you be willing to see if that solves your use case? And if so, open a modest PR attaching a functional test? Many thanks!

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