diff --git a/ChangeLog b/ChangeLog index f0cc1df31e..615941fb66 100644 --- a/ChangeLog +++ b/ChangeLog @@ -12,8 +12,13 @@ What's New in astroid 2.7.1? ============================ Release date: TBA +* When processing dataclass attributes, only do typing inference on collection types. + Support for instantiating other typing types is left for the future, if desired. + + * Fixed LookupMixIn missing from ``astroid.node_classes``. + Closes #1129 What's New in astroid 2.7.0? diff --git a/astroid/brain/brain_dataclasses.py b/astroid/brain/brain_dataclasses.py index f42c981cad..b4be357fc9 100644 --- a/astroid/brain/brain_dataclasses.py +++ b/astroid/brain/brain_dataclasses.py @@ -97,16 +97,7 @@ def infer_dataclass_attribute( if value is not None: yield from value.infer(context=ctx) if annotation is not None: - klass = None - try: - klass = next(annotation.infer()) - except (InferenceError, StopIteration): - yield Uninferable - - if not isinstance(klass, ClassDef): - yield Uninferable - else: - yield klass.instantiate_class() + yield from _infer_instance_from_annotation(annotation, ctx=ctx) else: yield Uninferable @@ -229,6 +220,44 @@ def _is_init_var(node: NodeNG) -> bool: return getattr(inferred, "name", "") == "InitVar" +# Allowed typing classes for which we support inferring instances +_INFERABLE_TYPING_TYPES = frozenset( + ( + "Dict", + "FrozenSet", + "List", + "Set", + "Tuple", + ) +) + + +def _infer_instance_from_annotation( + node: NodeNG, ctx: context.InferenceContext = None +) -> Generator: + """Infer an instance corresponding to the type annotation represented by node. + + Currently has limited support for the typing module. + """ + klass = None + try: + klass = next(node.infer(context=ctx)) + except (InferenceError, StopIteration): + yield Uninferable + if not isinstance(klass, ClassDef): + yield Uninferable + elif klass.root().name in ( + "typing", + "", + ): # "" because of synthetic nodes in brain_typing.py + if klass.name in _INFERABLE_TYPING_TYPES: + yield klass.instantiate_class() + else: + yield Uninferable + else: + yield klass.instantiate_class() + + if PY37_PLUS: AstroidManager().register_transform( ClassDef, dataclass_transform, is_decorated_with_dataclass diff --git a/tests/unittest_brain_dataclasses.py b/tests/unittest_brain_dataclasses.py index f7b08747f0..f90893d5cd 100644 --- a/tests/unittest_brain_dataclasses.py +++ b/tests/unittest_brain_dataclasses.py @@ -4,6 +4,7 @@ from astroid import bases, nodes from astroid.const import PY37_PLUS from astroid.exceptions import InferenceError +from astroid.util import Uninferable if not PY37_PLUS: pytest.skip("Dataclasses were added in 3.7", allow_module_level=True) @@ -235,3 +236,62 @@ class A: assert len(inferred) == 1 assert isinstance(inferred[0], nodes.Const) assert inferred[0].value == "hi" + + +def test_inference_generic_collection_attribute(): + """Test that an attribute with a generic collection type from the + typing module is inferred correctly. + """ + attr_nodes = astroid.extract_node( + """ + from dataclasses import dataclass, field + import typing + + @dataclass + class A: + dict_prop: typing.Dict[str, str] + frozenset_prop: typing.FrozenSet[str] + list_prop: typing.List[str] + set_prop: typing.Set[str] + tuple_prop: typing.Tuple[int, str] + + a = A({}, frozenset(), [], set(), (1, 'hi')) + a.dict_prop #@ + a.frozenset_prop #@ + a.list_prop #@ + a.set_prop #@ + a.tuple_prop #@ + """ + ) + names = ( + "Dict", + "FrozenSet", + "List", + "Set", + "Tuple", + ) + for node, name in zip(attr_nodes, names): + inferred = next(node.infer()) + assert isinstance(inferred, bases.Instance) + assert inferred.name == name + + +def test_inference_callable_attribute(): + """Test that an attribute with a Callable annotation is inferred as Uninferable. + + See issue#1129. + """ + instance = astroid.extract_node( + """ + from dataclasses import dataclass + from typing import Any, Callable + + @dataclass + class A: + enabled: Callable[[Any], bool] + + A(lambda x: x == 42).enabled #@ + """ + ) + inferred = next(instance.infer()) + assert inferred is Uninferable