Fix inference of self in a list or tuple within bin. ops. (#1360)

Author: DanielNoord

ChangeLog

@@ -6,6 +6,12 @@ What's New in astroid 2.10.0?
 =============================
 Release date: TBA
 
+
+* Fixed inference of ``self`` in binary operations in which ``self``
+  is part of a list or tuple.
+
+  Closes PyCQA/pylint#4826
+
 * Fixed builtin inferenence on `property` calls not calling the `postinit` of the new node, which
   resulted in instance arguments missing on these nodes.
 

astroid/protocols.py

@@ -185,7 +185,22 @@ def _filter_uninferable_nodes(elts, context):
 
 
 @decorators.yes_if_nothing_inferred
-def tl_infer_binary_op(self, opnode, operator, other, context, method):
+def tl_infer_binary_op(
+    self,
+    opnode: nodes.BinOp,
+    operator: str,
+    other: nodes.NodeNG,
+    context: InferenceContext,
+    method: nodes.FunctionDef,
+) -> Generator[nodes.NodeNG, None, None]:
+    """Infer a binary operation on a tuple or list.
+
+    The instance on which the binary operation is performed is a tuple
+    or list. This refers to the left-hand side of the operation, so:
+    'tuple() + 1' or '[] + A()'
+    """
+    # For tuples and list the boundnode is no longer the tuple or list instance
+    context.boundnode = None
     not_implemented = nodes.Const(NotImplemented)
     if isinstance(other, self.__class__) and operator == "+":
         node = self.__class__(parent=opnode)

tests/unittest_inference.py

@@ -3009,6 +3009,34 @@ def __radd__(self, other):
         for node in ast_nodes:
             self.assertEqual(next(node.infer()), util.Uninferable)
 
+    def test_binop_self_in_list(self) -> None:
+        """If 'self' is referenced within a list it should not be bound by it.
+
+        Reported in https://github.com/PyCQA/pylint/issues/4826.
+        """
+        ast_nodes = extract_node(
+            """
+        class A:
+            def __init__(self):
+                for a in [self] + []:
+                    print(a) #@
+
+        class B:
+            def __init__(self):
+                for b in [] + [self]:
+                    print(b) #@
+        """
+        )
+        inferred_a = list(ast_nodes[0].args[0].infer())
+        self.assertEqual(len(inferred_a), 1)
+        self.assertIsInstance(inferred_a[0], Instance)
+        self.assertEqual(inferred_a[0]._proxied.name, "A")
+
+        inferred_b = list(ast_nodes[1].args[0].infer())
+        self.assertEqual(len(inferred_b), 1)
+        self.assertIsInstance(inferred_b[0], Instance)
+        self.assertEqual(inferred_b[0]._proxied.name, "B")
+
     def test_metaclass__getitem__(self) -> None:
         ast_node = extract_node(
             """