TypeAliasType can leak memory if name is a str subclass #140000
Description
Bug report
Bug description:
TypeAliasType's traverse implementation does not visit its name. This means that we can leak memory if name is passed an instance of a mutable str subclass.
from typing import TypeAliasType import weakref import gc class S(str): pass def still_alive(ref): obj = ref() if not isinstance(obj, S): return False T = obj.T if not isinstance(T, TypeAliasType): return False return T name = S("name") T = TypeAliasType(name, int) name.T = T ref = weakref.ref(name) assert still_alive(ref) del name del T gc.collect() gc.collect() assert still_alive(ref) del ref().T assert not still_alive(ref)CPython versions tested on:
CPython main branch
Operating systems tested on:
macOS
Linked PRs
- gh-140000: Traverse
nameattribute forTypeVar,TypeVarTuple,TypeAliasType,ParamSpec#140016 - [3.14] gh-140000: Traverse
nameattribute forTypeVar,TypeVarTuple,TypeAliasType,ParamSpec(GH-140016) #140063 - [3.13] gh-140000: Traverse
nameattribute forTypeVar,TypeVarTuple,TypeAliasType,ParamSpec(GH-140016) #140073