Fix the variables check to not emit false positives for E0602 on {list,generator} comprehension loop variables inside decorators.

Closes #77982

3 files changed, 24 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 6ebe87919..b75206f81 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,9 @@ ChangeLog for PyLint
 
 	--
 
+    * #77982 Do not emit E0602 for loop variables of comprehensions
+      used as argument values inside a decorator (patch by tmarek@google.com)
+
     * #87192 fix crash when decorators are accessed through more than one dot
       (for instance @a.b is fine, @a.b.c crash)
     * #89092: don't emit E0202 (attribute hiding a method) on @property methods
diff --git a/checkers/utils.py b/checkers/utils.py
index 95574d4ef..efaa7ada8 100644
--- a/checkers/utils.py
+++ b/checkers/utils.py
@@ -20,6 +20,7 @@
 
 import string
 from logilab import astng
+from logilab.astng import scoped_nodes
 from logilab.common.compat import builtins
 BUILTINS_NAME = builtins.__name__
 
@@ -169,7 +170,10 @@ def is_func_decorator(node):
     while parent is not None:
         if isinstance(parent, astng.Decorators):
             return True
-        if parent.is_statement or isinstance(parent, astng.Lambda):
+        if (parent.is_statement or
+            isinstance(parent, astng.Lambda) or
+            isinstance(parent, (scoped_nodes.ComprehensionScope,
+                                scoped_nodes.ListComp))):
             break
         parent = parent.parent
     return False
diff --git a/test/input/func_undefined_var.py b/test/input/func_undefined_var.py
index 5d46f0104..27a9ed616 100644
--- a/test/input/func_undefined_var.py
+++ b/test/input/func_undefined_var.py
@@ -67,3 +67,19 @@ def if_branch_test(something):
     else:
         print xxx
         xxx = 3
+
+
+def decorator(arg):
+    """Decorator with one argument."""
+    return lambda: list(arg)
+
+
+@decorator(arg=[i * 2 for i in range(15)])
+def func1():
+    """A function with a decorator that contains a listcomp."""
+    pass
+
+@decorator(arg=(i * 2 for i in range(15)))
+def func2():
+    """A function with a decorator that contains a genexpr."""
+    pass