fix: correctly handle deserialising cls fields

src/finch/_models.py

@@ -179,14 +179,14 @@ def __str__(self) -> str:
     @classmethod
     @override
     def construct(  # pyright: ignore[reportIncompatibleMethodOverride]
-        cls: Type[ModelT],
+        __cls: Type[ModelT],
         _fields_set: set[str] | None = None,
         **values: object,
     ) -> ModelT:
-        m = cls.__new__(cls)
+        m = __cls.__new__(__cls)
         fields_values: dict[str, object] = {}
 
-        config = get_model_config(cls)
+        config = get_model_config(__cls)
         populate_by_name = (
             config.allow_population_by_field_name
             if isinstance(config, _ConfigProtocol)
@@ -196,7 +196,7 @@ def construct(  # pyright: ignore[reportIncompatibleMethodOverride]
         if _fields_set is None:
             _fields_set = set()
 
-        model_fields = get_model_fields(cls)
+        model_fields = get_model_fields(__cls)
         for name, field in model_fields.items():
             key = field.alias
             if key is None or (key not in values and populate_by_name):

tests/test_models.py

@@ -844,3 +844,13 @@ class Model(BaseModel):
     assert m.alias == "foo"
     assert isinstance(m.union, str)
     assert m.union == "bar"
+
+
+@pytest.mark.skipif(not PYDANTIC_V2, reason="TypeAliasType is not supported in Pydantic v1")
+def test_field_named_cls() -> None:
+    class Model(BaseModel):
+        cls: str
+
+    m = construct_type(value={"cls": "foo"}, type_=Model)
+    assert isinstance(m, Model)
+    assert isinstance(m.cls, str)