Make ``self-cls-assignment`` check tuple assignment (#5268)

Co-authored-by: Marc Mueller <30130371+cdce8p@users.noreply.github.com>

5 files changed, 23 insertions, 20 deletions

diff --git a/ChangeLog b/ChangeLog
index 5526acf2e..565c6d9d0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -127,6 +127,8 @@ Release date: TBA
 
   Closes #4426
 
+* ``self-cls-assignment`` now also considers tuple assignment
+
 * Fix ``missing-function-docstring`` not being able to check ``__init__`` and other
   magic methods even if the ``no-docstring-rgx`` setting was set to do so
 
diff --git a/doc/whatsnew/2.12.rst b/doc/whatsnew/2.12.rst
index f3b6bc86c..3be3f3c7b 100644
--- a/doc/whatsnew/2.12.rst
+++ b/doc/whatsnew/2.12.rst
@@ -112,6 +112,8 @@ Other Changes
 
   Fixes part of #3688
 
+* ``self-cls-assignment`` now also considers tuple assignment
+
 * ``undefined-variable`` now correctly triggers for assignment expressions in if ... else statements
   This includes a basic form of control flow inference for if ... else statements using
   constant boolean values
diff --git a/pylint/checkers/variables.py b/pylint/checkers/variables.py
index 3ae5957c7..cf11e213c 100644
--- a/pylint/checkers/variables.py
+++ b/pylint/checkers/variables.py
@@ -61,7 +61,7 @@ import os
 import re
 import sys
 from functools import lru_cache
-from typing import DefaultDict, List, Tuple
+from typing import DefaultDict, List, Optional, Set, Tuple
 
 import astroid
 from astroid import nodes
@@ -2022,18 +2022,19 @@ class VariablesChecker(BaseChecker):
             return
         self._store_type_annotation_node(node.type_annotation)
 
-    def _check_self_cls_assign(self, node):
+    def _check_self_cls_assign(self, node: nodes.Assign) -> None:
         """Check that self/cls don't get assigned"""
-        assign_names = {
-            target.name
-            for target in node.targets
-            if isinstance(target, nodes.AssignName)
-        }
+        assign_names: Set[Optional[str]] = set()
+        for target in node.targets:
+            if isinstance(target, nodes.AssignName):
+                assign_names.add(target.name)
+            elif isinstance(target, nodes.Tuple):
+                assign_names.update(
+                    elt.name for elt in target.elts if isinstance(elt, nodes.AssignName)
+                )
         scope = node.scope()
         nonlocals_with_same_name = any(
-            child
-            for child in scope.body
-            if isinstance(child, nodes.Nonlocal) and assign_names & set(child.names)
+            child for child in scope.body if isinstance(child, nodes.Nonlocal)
         )
         if nonlocals_with_same_name:
             scope = node.scope().parent.scope()
@@ -2048,12 +2049,7 @@ class VariablesChecker(BaseChecker):
         if not argument_names:
             return
         self_cls_name = argument_names[0]
-        target_assign_names = (
-            target.name
-            for target in node.targets
-            if isinstance(target, nodes.AssignName)
-        )
-        if self_cls_name in target_assign_names:
+        if self_cls_name in assign_names:
             self.add_message("self-cls-assignment", node=node, args=(self_cls_name,))
 
     def _check_unpacking(self, inferred, node, targets):
diff --git a/tests/functional/s/self/self_cls_assignment.py b/tests/functional/s/self/self_cls_assignment.py
index 4e63bb422..e69dafd59 100644
--- a/tests/functional/s/self/self_cls_assignment.py
+++ b/tests/functional/s/self/self_cls_assignment.py
@@ -14,6 +14,8 @@ class Foo(object):
     def self_foofoo(self, lala):
         """Instance method, should warn for self"""
         self = lala  # [self-cls-assignment]
+        self, var = lala, 1  # [self-cls-assignment]
+        print(var)
 
     @classmethod
     def cls_foo(cls):
diff --git a/tests/functional/s/self/self_cls_assignment.txt b/tests/functional/s/self/self_cls_assignment.txt
index eeb2ca230..cedd256e0 100644
--- a/tests/functional/s/self/self_cls_assignment.txt
+++ b/tests/functional/s/self/self_cls_assignment.txt
@@ -1,4 +1,5 @@
-self-cls-assignment:11:8:Foo.self_foo:Invalid assignment to bar_ in method
-self-cls-assignment:16:8:Foo.self_foofoo:Invalid assignment to self in method
-self-cls-assignment:21:8:Foo.cls_foo:Invalid assignment to cls in method
-self-cls-assignment:44:12:TestNonLocal.function._set_param:Invalid assignment to self in method
+self-cls-assignment:11:8:Foo.self_foo:Invalid assignment to bar_ in method:HIGH
+self-cls-assignment:16:8:Foo.self_foofoo:Invalid assignment to self in method:HIGH
+self-cls-assignment:17:8:Foo.self_foofoo:Invalid assignment to self in method:HIGH
+self-cls-assignment:23:8:Foo.cls_foo:Invalid assignment to cls in method:HIGH
+self-cls-assignment:46:12:TestNonLocal.function._set_param:Invalid assignment to self in method:HIGH