Fix dangerous-default-value false negative when * is used. (#7856)

pylint-dev · Nov 27, 2022 · 7618b7e · 7618b7e
1 parent b950567
commit 7618b7e
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Showing 4 changed files with 16 additions and 1 deletion.
diff --git a/doc/whatsnew/fragments/7818.false_negative b/doc/whatsnew/fragments/7818.false_negative
@@ -0,0 +1,3 @@
+Fix ``dangerous-default-value`` false negative when `*` is used.
+
+Closes #7818
diff --git a/pylint/checkers/base/basic_checker.py b/pylint/checkers/base/basic_checker.py
@@ -572,7 +572,7 @@ def _check_dangerous_default(self, node: nodes.FunctionDef) -> None:
         def is_iterable(internal_node: nodes.NodeNG) -> bool:
             return isinstance(internal_node, (nodes.List, nodes.Set, nodes.Dict))
 
-        defaults = node.args.defaults or [] + node.args.kw_defaults or []
+        defaults = (node.args.defaults or []) + (node.args.kw_defaults or [])
         for default in defaults:
             if not default:
                 continue

diff --git a/tests/functional/d/dangerous_default_value.py b/tests/functional/d/dangerous_default_value.py
@@ -109,3 +109,14 @@ def function23(value=collections.UserList()):  # [dangerous-default-value]
 def function24(*, value=[]): # [dangerous-default-value]
     """dangerous default value in kwarg."""
     return value
+
+
+class Clazz:
+    # pylint: disable=too-few-public-methods
+    def __init__(  # [dangerous-default-value]
+        self,
+        arg: str = None,
+        *,
+        kk: dict = {},
+    ) -> None:
+        pass
diff --git a/tests/functional/d/dangerous_default_value.txt b/tests/functional/d/dangerous_default_value.txt
@@ -20,3 +20,4 @@ dangerous-default-value:97:0:97:14:function21:Dangerous default value defaultdic
 dangerous-default-value:101:0:101:14:function22:Dangerous default value UserDict() (collections.UserDict) as argument:UNDEFINED
 dangerous-default-value:105:0:105:14:function23:Dangerous default value UserList() (collections.UserList) as argument:UNDEFINED
 dangerous-default-value:109:0:109:14:function24:Dangerous default value [] as argument:UNDEFINED
+dangerous-default-value:116:4:116:16:Clazz.__init__:Dangerous default value {} as argument:UNDEFINED