Do not evaluate annotations for private fields (#10962)

Author: Viicos

pydantic/_internal/_fields.py

@@ -109,7 +109,7 @@ def collect_model_fields(  # noqa: C901
         if model_fields := getattr(base, '__pydantic_fields__', None):
             parent_fields_lookup.update(model_fields)
 
-    type_hints = _typing_extra.get_cls_type_hints(cls, ns_resolver=ns_resolver, lenient=True)
+    type_hints = _typing_extra.get_model_type_hints(cls, ns_resolver=ns_resolver)
 
     # https://docs.python.org/3/howto/annotations.html#accessing-the-annotations-dict-of-an-object-in-python-3-9-and-older
     # annotations is only used for finding fields in parent classes
@@ -216,7 +216,6 @@ def collect_model_fields(  # noqa: C901
                     # Nothing stops us from just creating a new FieldInfo for this type hint, so we do this.
                     field_info = FieldInfo_.from_annotation(ann_type)
                     field_info.evaluated = evaluated
-
         else:
             _warn_on_nested_alias_in_annotation(ann_type, ann_name)
             if isinstance(default, FieldInfo_) and ismethoddescriptor(default.default):

pydantic/_internal/_generate_schema.py

@@ -1432,9 +1432,7 @@ def _typed_dict_schema(self, typed_dict_cls: Any, origin: Any) -> core_schema.Co
                     field_docstrings = None
 
                 try:
-                    annotations = _typing_extra.get_cls_type_hints(
-                        typed_dict_cls, ns_resolver=self._ns_resolver, lenient=False
-                    )
+                    annotations = _typing_extra.get_cls_type_hints(typed_dict_cls, ns_resolver=self._ns_resolver)
                 except NameError as e:
                     raise PydanticUndefinedAnnotation.from_name_error(e) from e
 
@@ -1496,9 +1494,7 @@ def _namedtuple_schema(self, namedtuple_cls: Any, origin: Any) -> core_schema.Co
                 namedtuple_cls = origin
 
             try:
-                annotations = _typing_extra.get_cls_type_hints(
-                    namedtuple_cls, ns_resolver=self._ns_resolver, lenient=False
-                )
+                annotations = _typing_extra.get_cls_type_hints(namedtuple_cls, ns_resolver=self._ns_resolver)
             except NameError as e:
                 raise PydanticUndefinedAnnotation.from_name_error(e) from e
             if not annotations:

pydantic/_internal/_typing_extra.py

@@ -9,7 +9,7 @@
 import typing
 import warnings
 from functools import lru_cache, partial
-from typing import Any, Callable, Literal, overload
+from typing import TYPE_CHECKING, Any, Callable
 
 import typing_extensions
 from typing_extensions import TypeIs, deprecated, get_args, get_origin
@@ -23,6 +23,8 @@
     from types import EllipsisType as EllipsisType
     from types import NoneType as NoneType
 
+if TYPE_CHECKING:
+    from pydantic import BaseModel
 
 # See https://typing-extensions.readthedocs.io/en/latest/#runtime-use-of-types:
 
@@ -467,34 +469,57 @@ def _type_convert(arg: Any) -> Any:
     return arg
 
 
-@overload
-def get_cls_type_hints(
-    obj: type[Any],
-    *,
-    ns_resolver: NsResolver | None = None,
-    lenient: Literal[True],
-) -> dict[str, tuple[Any, bool]]: ...
-@overload
-def get_cls_type_hints(
-    obj: type[Any],
+def get_model_type_hints(
+    obj: type[BaseModel],
     *,
     ns_resolver: NsResolver | None = None,
-    lenient: Literal[False] = ...,
-) -> dict[str, Any]: ...
+) -> dict[str, tuple[Any, bool]]:
+    """Collect annotations from a Pydantic model class, including those from parent classes.
+
+    Args:
+        obj: The Pydantic model to inspect.
+        ns_resolver: A namespace resolver instance to use. Defaults to an empty instance.
+
+    Returns:
+        A dictionary mapping annotation names to a two-tuple: the first element is the evaluated
+        type or the original annotation if a `NameError` occurred, the second element is a boolean
+        indicating if whether the evaluation succeeded.
+    """
+    hints: dict[str, Any] | dict[str, tuple[Any, bool]] = {}
+    ns_resolver = ns_resolver or NsResolver()
+
+    for base in reversed(obj.__mro__):
+        ann: dict[str, Any] | None = base.__dict__.get('__annotations__')
+        if not ann or isinstance(ann, types.GetSetDescriptorType):
+            continue
+        with ns_resolver.push(base):
+            globalns, localns = ns_resolver.types_namespace
+            for name, value in ann.items():
+                if name.startswith('_'):
+                    # For private attributes, we only need the annotation to detect the `ClassVar` special form.
+                    # For this reason, we still try to evaluate it, but we also catch any possible exception (on
+                    # top of the `NameError`s caught in `try_eval_type`) that could happen so that users are free
+                    # to use any kind of forward annotation for private fields (e.g. circular imports, new typing
+                    # syntax, etc).
+                    try:
+                        hints[name] = try_eval_type(value, globalns, localns)
+                    except Exception:
+                        hints[name] = (value, False)
+                else:
+                    hints[name] = try_eval_type(value, globalns, localns)
+    return hints
+
+
 def get_cls_type_hints(
     obj: type[Any],
     *,
     ns_resolver: NsResolver | None = None,
-    lenient: bool = False,
-) -> dict[str, Any] | dict[str, tuple[Any, bool]]:
+) -> dict[str, Any]:
     """Collect annotations from a class, including those from parent classes.
 
     Args:
         obj: The class to inspect.
         ns_resolver: A namespace resolver instance to use. Defaults to an empty instance.
-        lenient: Whether to keep unresolvable annotations as is or re-raise the `NameError` exception.
-            If lenient, an extra boolean flag is set for each annotation value to indicate whether the
-            evaluation succeeded or not. Default: re-raise.
     """
     hints: dict[str, Any] | dict[str, tuple[Any, bool]] = {}
     ns_resolver = ns_resolver or NsResolver()
@@ -506,10 +531,7 @@ def get_cls_type_hints(
         with ns_resolver.push(base):
             globalns, localns = ns_resolver.types_namespace
             for name, value in ann.items():
-                if lenient:
-                    hints[name] = try_eval_type(value, globalns, localns)
-                else:
-                    hints[name] = eval_type(value, globalns, localns)
+                hints[name] = eval_type(value, globalns, localns)
     return hints
 
 

tests/test_forward_ref.py

@@ -598,6 +598,13 @@ class Model(BaseModel):
     assert module.Model.__private_attributes__ == {}
 
 
+def test_private_attr_annotation_not_evaluated() -> None:
+    class Model(BaseModel):
+        _a: 'UnknownAnnotation'
+
+    assert '_a' in Model.__private_attributes__
+
+
 def test_json_encoder_str(create_module):
     module = create_module(
         # language=Python