Fix typealias structuring (#485)

* Fix typealias structuring

* Upgrade ruff

Author: Tinche

pdm.lock

@@ -262,7 +262,7 @@ def is_tuple(type):
     if sys.version_info >= (3, 12):
         from typing import TypeAliasType
 
-        def is_type_alias(type: Any) -> bool:  # noqa: F811
+        def is_type_alias(type: Any) -> bool:
             """Is this a PEP 695 type alias?"""
             return isinstance(type, TypeAliasType)
 

src/cattrs/_compat.py

@@ -486,7 +486,7 @@ def _find_type_alias_structure_hook(self, type: Any) -> StructureHook:
         if res == self._structure_call:
             # we need to replace the type arg of `structure_call`
             return lambda v, _, __base=base: self._structure_call(v, __base)
-        return res
+        return lambda v, _, __base=base: res(v, __base)
 
     def _structure_final_factory(self, type):
         base = get_final_base(type)

src/cattrs/converters.py

@@ -72,3 +72,19 @@ def test_type_aliases_overwrite_base_hooks(converter: BaseConverter):
 
     assert converter.structure(1, my_int) == 11
     assert converter.unstructure(100, my_int) == 80
+
+
+def test_type_alias_with_children(converter: BaseConverter):
+    """A type alias that chains to a hook that requires the type parameter works."""
+
+    class TestClass:
+        pass
+
+    def structure_testclass(val, type):
+        assert type is TestClass
+        return TestClass
+
+    converter.register_structure_hook(TestClass, structure_testclass)
+
+    type TestAlias = TestClass
+    assert converter.structure(None, TestAlias) is TestClass