Fix false positive for unused-variable for a comprehension variable matching a type annotation (#5651)

* Close #5326

Author: jacobtylerwalls

ChangeLog

@@ -99,6 +99,11 @@ Release date: TBA
 
   Closes #5461
 
+* Fix false positive for ``unused-variable`` for a comprehension variable matching
+  an outer scope type annotation.
+
+  Closes #5326
+
 * Some files in ``pylint.testutils`` were deprecated. In the future imports should be done from the
   ``pylint.testutils.functional`` namespace directly.
 

doc/whatsnew/2.13.rst

@@ -131,6 +131,11 @@ Other Changes
 
   Closes #5461
 
+* Fix false positive for ``unused-variable`` for a comprehension variable matching
+  an outer scope type annotation.
+
+  Closes #5326
+
 * Require Python ``3.6.2`` to run pylint.
 
   Closes #5065

pylint/checkers/variables.py

@@ -1849,7 +1849,7 @@ def _is_only_type_assignment(node: nodes.Name, defstmt: nodes.Statement) -> bool
                 # Local refs are ordered, so we break.
                 #     print(var)
                 #     var = 1  # <- irrelevant
-                if defstmt_frame == node_frame and not ref_node.lineno < node.lineno:
+                if defstmt_frame == node_frame and ref_node.lineno > node.lineno:
                     break
 
                 # If the parent of the local reference is anything but an AnnAssign

tests/functional/u/undefined/undefined_variable_py38.py

@@ -11,10 +11,10 @@ def typing_and_assignment_expression():
         print(var)
 
 
-def typing_and_self_referncing_assignment_expression():
+def typing_and_self_referencing_assignment_expression():
     """The variable gets assigned in an assignment expression that references itself"""
     var: int
-    if (var := var ** 2): # [undefined-variable]
+    if (var := var ** 2):  # false negative--walrus operator!
         print(var)
 
 
@@ -108,3 +108,20 @@ def no_parameters_in_function_default() -> None:
     if (x_0 := thing.this_value) < (x_1 := thing.that_value)
     else x_1,
 )
+
+
+# Tests for type annotation reused in comprehension
+
+def type_annotation_used_after_comprehension():
+    """https://github.com/PyCQA/pylint/issues/5326#issuecomment-982635371"""
+    my_int: int
+    ints = [my_int + 1 for my_int in range(5)]
+
+    for my_int in ints:
+        print(my_int)
+
+
+def type_annotation_unused_after_comprehension():
+    """https://github.com/PyCQA/pylint/issues/5326"""
+    my_int: int
+    _ = [print(kwarg1=my_int, kwarg2=my_int) for my_int in range(10)]

tests/functional/u/undefined/undefined_variable_py38.txt

@@ -1,4 +1,3 @@
-undefined-variable:17:15:17:18:typing_and_self_referncing_assignment_expression:Undefined variable 'var':UNDEFINED
 undefined-variable:42:6:42:16::Undefined variable 'no_default':UNDEFINED
 undefined-variable:50:6:50:22::Undefined variable 'again_no_default':UNDEFINED
 undefined-variable:76:6:76:19::Undefined variable 'else_assign_1':UNDEFINED