Fix crash for unneccessary-ellipsis checker when an ellipsis is used inside of a list.

Closes #6037

Author: Mark Byrne

ChangeLog

@@ -28,6 +28,10 @@ Release date: TBA
 
 * Fix bug where specifically enabling just ``await-outside-async`` was not possible.
 
+* Fix crash for ``unneccessary-ellipsis`` checker when an ellipsis is used inside of a list.
+
+  Closes #6037
+
 ..
   Insert your changelog randomly, it will reduce merge conflicts
   (Ie. not necessarily at the end)

pylint/checkers/ellipsis_checker.py

@@ -43,7 +43,7 @@ def visit_const(self, node: nodes.Const) -> None:
             node.pytype() == "builtins.Ellipsis"
             and not isinstance(
                 node.parent,
-                (nodes.Assign, nodes.AnnAssign, nodes.Call, nodes.Arguments),
+                (nodes.Assign, nodes.AnnAssign, nodes.Call, nodes.Arguments, nodes.List),
             )
             and (
                 len(node.parent.parent.child_sequence(node.parent)) > 1

tests/functional/u/unnecessary/unnecessary_ellipsis.py

@@ -101,3 +101,8 @@ def __getitem__(self, index: Union[int, slice]) -> Union[int, List[int]]:
 # Ellipsis is allowed as a default argument
 def func_with_ellipsis_default_arg(a = ...) -> None:
     "Some docstring."
+
+
+# Ignore if the ellipsis is inside a list
+x = [...]
+y = {'a': [...]}