Narrow the scope of the unnecessary-ellipsis checker (#6081)

* Narrow the scope of the ``unnecessary-ellipsis`` checker to functions & classes which contain both a docstring and an ellipsis.
* Emit the warning when the body contains an ellipsis expression and at least one
other item.

Co-authored-by: Daniël van Noord <[email protected]>

Author: 2 people

ChangeLog

@@ -20,6 +20,10 @@ What's New in Pylint 2.13.5?
 ============================
 Release date: TBA
 
+* Narrow the scope of the ``unnecessary-ellipsis`` checker to:
+  * functions & classes which contain both a docstring and an ellipsis.
+  * A body which contains an ellipsis ``nodes.Expr`` node & at least one other statement.
+
 
 
 What's New in Pylint 2.13.4?

pylint/checkers/ellipsis_checker.py

@@ -41,23 +41,13 @@ def visit_const(self, node: nodes.Const) -> None:
         """
         if (
             node.pytype() == "builtins.Ellipsis"
-            and not isinstance(
-                node.parent,
-                (
-                    nodes.AnnAssign,
-                    nodes.Arguments,
-                    nodes.Assign,
-                    nodes.BaseContainer,
-                    nodes.Call,
-                    nodes.Lambda,
-                ),
-            )
+            and isinstance(node.parent, nodes.Expr)
             and (
-                len(node.parent.parent.child_sequence(node.parent)) > 1
-                or (
+                (
                     isinstance(node.parent.parent, (nodes.ClassDef, nodes.FunctionDef))
                     and node.parent.parent.doc_node
                 )
+                or len(node.parent.parent.body) > 1
             )
         ):
             self.add_message("unnecessary-ellipsis", node=node)

tests/functional/u/unnecessary/unnecessary_ellipsis.py

@@ -9,10 +9,10 @@
     A = 2
 except ValueError:
     A = 24
-    ... # [unnecessary-ellipsis]
+    ...  # [unnecessary-ellipsis]
 
 def ellipsis_and_subsequent_statement():
-    ... # [unnecessary-ellipsis]
+    ...  # [unnecessary-ellipsis]
     return 0
 
 # The parent of ellipsis is an assignment