False positive from used-before-assignment when variable is reimported

[MarcoGorelli]

Bug description

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from foo import Bar

def myfunc():
    result: Bar

    from foo import Bar # if I remove this, then no error is reported

Note how if I remove the from foo import Bar line, then the error goes away

Command used

pylint --disable=all --enable=used-before-assignment t.py

Pylint output

************* Module t
t.py:7:12: E0601: Using variable 'Bar' before assignment (used-before-assignment)

------------------------------------------------------------------
Your code has been rated at 1.67/10 (previous run: 1.67/10, +0.00)

Expected behavior

No error reported

Pylint version

pylint 2.15.7
astroid 2.12.13
Python 3.8.15 (default, Oct 12 2022, 19:15:16) 
[GCC 11.2.0]

[orSolocate]

Maybe it is an astroid issue and not Pylint?
Would be interesting to debug the infer used on Bar during used-before-assignment check..

[mbyrnepr2]

Thanks for the report.

I think Pylint is struggling with this:

if TYPE_CHECKING:
    from foo import Bar

Replacing with the following makes the false positive go away:

from foo import Bar

[jacobtylerwalls]

Very similar to #7609, we need to account for the fact that annotations are not evaluated at runtime in the body of a function.

This appears to work:

diff --git a/pylint/checkers/variables.py b/pylint/checkers/variables.py
index 0d72ef969..486137ada 100644
--- a/pylint/checkers/variables.py
+++ b/pylint/checkers/variables.py
@@ -1799,17 +1799,20 @@ class VariablesChecker(BaseChecker):
                 # E0601 may *not* occurs in lambda scope.
 
                 # Handle postponed evaluation of annotations
-                if not (
-                    self._postponed_evaluation_enabled
-                    and isinstance(stmt, (nodes.AnnAssign, nodes.FunctionDef))
+                if self._postponed_evaluation_enabled and isinstance(stmt, nodes.FunctionDef):
+                    return (VariableVisitConsumerAction.CONTINUE, [node])
+                # Handle unevaluated annotation inside the body of a function)
+                if (
+                    isinstance(stmt, nodes.AnnAssign)
+                    and utils.get_node_first_ancestor_of_type(stmt, nodes.FunctionDef)
                 ):
-                    self.add_message(
-                        "used-before-assignment",
-                        args=node.name,
-                        node=node,
-                        confidence=HIGH,
-                    )
-                    return (VariableVisitConsumerAction.RETURN, found_nodes)
+                    return (VariableVisitConsumerAction.CONTINUE, [node])
+                self.add_message(
+                    "used-before-assignment",
+                    args=node.name,
+                    node=node,
+                    confidence=HIGH,
+                )
 
             elif base_scope_type == "lambda":
                 # E0601 can occur in class-level scope in lambdas, as in