Create UninferableBase

ChangeLog

@@ -10,6 +10,11 @@ Release date: TBA
 
   Refs PyCQA/pylint#7306
 
+* ``Uninferable`` now has the type ``UninferableBase``. This is to facilitate correctly type annotating
+  code that uses this singleton.
+
+  Closes #1680
+
 
 What's New in astroid 2.14.2?
 =============================

astroid/arguments.py

@@ -8,7 +8,7 @@
 from astroid.bases import Instance
 from astroid.context import CallContext, InferenceContext
 from astroid.exceptions import InferenceError, NoDefault
-from astroid.util import Uninferable
+from astroid.util import Uninferable, UninferableBase
 
 
 class CallSite:
@@ -44,12 +44,12 @@ def __init__(
         self._unpacked_kwargs = self._unpack_keywords(keywords, context=context)
 
         self.positional_arguments = [
-            arg for arg in self._unpacked_args if arg is not Uninferable
+            arg for arg in self._unpacked_args if not isinstance(arg, UninferableBase)
         ]
         self.keyword_arguments = {
             key: value
             for key, value in self._unpacked_kwargs.items()
-            if value is not Uninferable
+            if not isinstance(value, UninferableBase)
         }
 
     @classmethod
@@ -142,7 +142,7 @@ def _unpack_args(self, args, context: InferenceContext | None = None):
                 except StopIteration:
                     continue
 
-                if inferred is Uninferable:
+                if isinstance(inferred, UninferableBase):
                     values.append(Uninferable)
                     continue
                 if not hasattr(inferred, "elts"):

astroid/bases.py

@@ -28,7 +28,7 @@
     NameInferenceError,
 )
 from astroid.typing import InferBinaryOp, InferenceErrorInfo, InferenceResult
-from astroid.util import Uninferable, lazy_descriptor, lazy_import
+from astroid.util import Uninferable, UninferableBase, lazy_descriptor, lazy_import
 
 if sys.version_info >= (3, 8):
     from typing import Literal
@@ -79,7 +79,9 @@ def _is_property(meth, context: InferenceContext | None = None) -> bool:
     if PROPERTIES.intersection(decoratornames):
         return True
     stripped = {
-        name.split(".")[-1] for name in decoratornames if name is not Uninferable
+        name.split(".")[-1]
+        for name in decoratornames
+        if not isinstance(name, UninferableBase)
     }
     if any(name in stripped for name in POSSIBLE_PROPERTIES):
         return True
@@ -89,7 +91,7 @@ def _is_property(meth, context: InferenceContext | None = None) -> bool:
         return False
     for decorator in meth.decorators.nodes or ():
         inferred = helpers.safe_infer(decorator, context=context)
-        if inferred is None or inferred is Uninferable:
+        if inferred is None or isinstance(inferred, UninferableBase):
             continue
         if inferred.__class__.__name__ == "ClassDef":
             for base_class in inferred.bases:
@@ -144,7 +146,7 @@ def infer(  # type: ignore[return]
 
 
 def _infer_stmts(
-    stmts: Sequence[nodes.NodeNG | type[Uninferable] | Instance],
+    stmts: Sequence[nodes.NodeNG | UninferableBase | Instance],
     context: InferenceContext | None,
     frame: nodes.NodeNG | Instance | None = None,
 ) -> collections.abc.Generator[InferenceResult, None, None]:
@@ -161,7 +163,7 @@ def _infer_stmts(
         context = InferenceContext()
 
     for stmt in stmts:
-        if stmt is Uninferable:
+        if isinstance(stmt, UninferableBase):
             yield stmt
             inferred = True
             continue
@@ -172,8 +174,7 @@ def _infer_stmts(
             for constraint_stmt, potential_constraints in constraints.items():
                 if not constraint_stmt.parent_of(stmt):
                     stmt_constraints.update(potential_constraints)
-            # Mypy doesn't recognize that 'stmt' can't be Uninferable
-            for inf in stmt.infer(context=context):  # type: ignore[union-attr]
+            for inf in stmt.infer(context=context):
                 if all(constraint.satisfied_by(inf) for constraint in stmt_constraints):
                     yield inf
                     inferred = True
@@ -206,7 +207,7 @@ def _infer_method_result_truth(instance, method_name, context):
         try:
             context.callcontext = CallContext(args=[], callee=meth)
             for value in meth.infer_call_result(instance, context=context):
-                if value is Uninferable:
+                if isinstance(value, UninferableBase):
                     return value
                 try:
                     inferred = next(value.infer(context=context))
@@ -316,7 +317,7 @@ def infer_call_result(
 
         # Otherwise we infer the call to the __call__ dunder normally
         for node in self._proxied.igetattr("__call__", context):
-            if node is Uninferable or not node.callable():
+            if isinstance(node, UninferableBase) or not node.callable():
                 continue
             for res in node.infer_call_result(caller, context):
                 inferred = True
@@ -458,7 +459,7 @@ def _infer_builtin_new(
         caller: nodes.Call,
         context: InferenceContext,
     ) -> collections.abc.Generator[
-        nodes.Const | Instance | type[Uninferable], None, None
+        nodes.Const | Instance | UninferableBase, None, None
     ]:
         if not caller.args:
             return
@@ -477,7 +478,7 @@ def _infer_builtin_new(
 
         node_context = context.extra_context.get(caller.args[0])
         for inferred in caller.args[0].infer(context=node_context):
-            if inferred is Uninferable:
+            if isinstance(inferred, UninferableBase):
                 yield inferred
             if isinstance(inferred, nodes.ClassDef):
                 yield Instance(inferred)

astroid/brain/brain_builtin_inference.py

@@ -209,10 +209,10 @@ def _container_generic_inference(node, context, node_type, transform):
             inferred = next(arg.infer(context=context))
         except (InferenceError, StopIteration) as exc:
             raise UseInferenceDefault from exc
-        if inferred is util.Uninferable:
+        if isinstance(inferred, util.UninferableBase):
             raise UseInferenceDefault
         transformed = transform(inferred)
-    if not transformed or transformed is util.Uninferable:
+    if not transformed or isinstance(transformed, util.UninferableBase):
         raise UseInferenceDefault
     return transformed
 
@@ -423,7 +423,9 @@ def infer_super(node, context: InferenceContext | None = None):
         except (InferenceError, StopIteration) as exc:
             raise UseInferenceDefault from exc
 
-    if mro_pointer is util.Uninferable or mro_type is util.Uninferable:
+    if isinstance(mro_pointer, util.UninferableBase) or isinstance(
+        mro_type, util.UninferableBase
+    ):
         # No way we could understand this.
         raise UseInferenceDefault
 
@@ -445,7 +447,7 @@ def _infer_getattr_args(node, context):
     except (InferenceError, StopIteration) as exc:
         raise UseInferenceDefault from exc
 
-    if obj is util.Uninferable or attr is util.Uninferable:
+    if isinstance(obj, util.UninferableBase) or isinstance(attr, util.UninferableBase):
         # If one of the arguments is something we can't infer,
         # then also make the result of the getattr call something
         # which is unknown.
@@ -467,8 +469,8 @@ def infer_getattr(node, context: InferenceContext | None = None):
     """
     obj, attr = _infer_getattr_args(node, context)
     if (
-        obj is util.Uninferable
-        or attr is util.Uninferable
+        isinstance(obj, util.UninferableBase)
+        or isinstance(attr, util.UninferableBase)
         or not hasattr(obj, "igetattr")
     ):
         return util.Uninferable
@@ -498,8 +500,8 @@ def infer_hasattr(node, context: InferenceContext | None = None):
     try:
         obj, attr = _infer_getattr_args(node, context)
         if (
-            obj is util.Uninferable
-            or attr is util.Uninferable
+            isinstance(obj, util.UninferableBase)
+            or isinstance(attr, util.UninferableBase)
             or not hasattr(obj, "getattr")
         ):
             return util.Uninferable
@@ -530,7 +532,7 @@ def infer_callable(node, context: InferenceContext | None = None):
         inferred = next(argument.infer(context=context))
     except (InferenceError, StopIteration):
         return util.Uninferable
-    if inferred is util.Uninferable:
+    if isinstance(inferred, util.UninferableBase):
         return util.Uninferable
     return nodes.Const(inferred.callable())
 
@@ -585,11 +587,11 @@ def infer_bool(node, context: InferenceContext | None = None):
         inferred = next(argument.infer(context=context))
     except (InferenceError, StopIteration):
         return util.Uninferable
-    if inferred is util.Uninferable:
+    if isinstance(inferred, util.UninferableBase):
         return util.Uninferable
 
     bool_value = inferred.bool_value(context=context)
-    if bool_value is util.Uninferable:
+    if isinstance(bool_value, util.UninferableBase):
         return util.Uninferable
     return nodes.Const(bool_value)
 
@@ -611,7 +613,7 @@ def infer_slice(node, context: InferenceContext | None = None):
     infer_func = partial(helpers.safe_infer, context=context)
     args = [infer_func(arg) for arg in args]
     for arg in args:
-        if not arg or arg is util.Uninferable:
+        if not arg or isinstance(arg, util.UninferableBase):
             raise UseInferenceDefault
         if not isinstance(arg, nodes.Const):
             raise UseInferenceDefault
@@ -725,7 +727,7 @@ def infer_isinstance(callnode, context: InferenceContext | None = None):
         raise UseInferenceDefault("TypeError: " + str(exc)) from exc
     except MroError as exc:
         raise UseInferenceDefault from exc
-    if isinstance_bool is util.Uninferable:
+    if isinstance(isinstance_bool, util.UninferableBase):
         raise UseInferenceDefault
     return nodes.Const(isinstance_bool)
 
@@ -811,7 +813,7 @@ def infer_int(node, context: InferenceContext | None = None):
         except (InferenceError, StopIteration) as exc:
             raise UseInferenceDefault(str(exc)) from exc
 
-        if first_value is util.Uninferable:
+        if isinstance(first_value, util.UninferableBase):
             raise UseInferenceDefault
 
         if isinstance(first_value, nodes.Const) and isinstance(
@@ -924,7 +926,7 @@ def _is_str_format_call(node: nodes.Call) -> bool:
 
 def _infer_str_format_call(
     node: nodes.Call, context: InferenceContext | None = None
-) -> Iterator[nodes.Const | type[util.Uninferable]]:
+) -> Iterator[nodes.Const | util.UninferableBase]:
     """Return a Const node based on the template and passed arguments."""
     call = arguments.CallSite.from_call(node, context=context)
     if isinstance(node.func.expr, nodes.Name):

astroid/brain/brain_dataclasses.py

@@ -25,7 +25,7 @@
 from astroid.inference_tip import inference_tip
 from astroid.manager import AstroidManager
 from astroid.typing import InferenceResult
-from astroid.util import Uninferable
+from astroid.util import Uninferable, UninferableBase
 
 if sys.version_info >= (3, 8):
     from typing import Literal
@@ -446,7 +446,7 @@ def _looks_like_dataclass_decorator(
     except (InferenceError, StopIteration):
         inferred = Uninferable
 
-    if inferred is Uninferable:
+    if isinstance(inferred, UninferableBase):
         if isinstance(node, nodes.Name):
             return node.name in decorator_names
         if isinstance(node, nodes.Attribute):
@@ -594,7 +594,7 @@ def _is_init_var(node: nodes.NodeNG) -> bool:
 
 def _infer_instance_from_annotation(
     node: nodes.NodeNG, ctx: context.InferenceContext | None = None
-) -> Iterator[type[Uninferable] | bases.Instance]:
+) -> Iterator[UninferableBase | bases.Instance]:
     """Infer an instance corresponding to the type annotation represented by node.
 
     Currently has limited support for the typing module.

astroid/brain/brain_functools.py

@@ -18,7 +18,7 @@
 from astroid.manager import AstroidManager
 from astroid.nodes.node_classes import AssignName, Attribute, Call, Name
 from astroid.nodes.scoped_nodes import FunctionDef
-from astroid.util import Uninferable
+from astroid.util import UninferableBase
 
 LRU_CACHE = "functools.lru_cache"
 
@@ -84,7 +84,7 @@ def _functools_partial_inference(
         inferred_wrapped_function = next(partial_function.infer(context=context))
     except (InferenceError, StopIteration) as exc:
         raise UseInferenceDefault from exc
-    if inferred_wrapped_function is Uninferable:
+    if isinstance(inferred_wrapped_function, UninferableBase):
         raise UseInferenceDefault("Cannot infer the wrapped function")
     if not isinstance(inferred_wrapped_function, FunctionDef):
         raise UseInferenceDefault("The wrapped function is not a function")

astroid/brain/brain_namedtuple_enum.py

@@ -52,13 +52,13 @@
 
 
 def _infer_first(node, context):
-    if node is util.Uninferable:
+    if isinstance(node, util.UninferableBase):
         raise UseInferenceDefault
     try:
         value = next(node.infer(context=context))
     except StopIteration as exc:
         raise InferenceError from exc
-    if value is util.Uninferable:
+    if isinstance(value, util.UninferableBase):
         raise UseInferenceDefault()
     return value
 

astroid/brain/brain_typing.py

@@ -33,7 +33,6 @@
     Tuple,
 )
 from astroid.nodes.scoped_nodes import ClassDef, FunctionDef
-from astroid.util import Uninferable
 
 if sys.version_info >= (3, 8):
     from typing import Final
@@ -297,7 +296,7 @@ def infer_typing_alias(
         col_offset=assign_name.col_offset,
         parent=node.parent,
     )
-    if res != Uninferable and isinstance(res, ClassDef):
+    if isinstance(res, ClassDef):
         # Only add `res` as base if it's a `ClassDef`
         # This isn't the case for `typing.Pattern` and `typing.Match`
         class_def.postinit(bases=[res], body=[], decorators=None)

astroid/builder.py

@@ -238,7 +238,7 @@ def delayed_assattr(self, node: nodes.AssignAttr) -> None:
         try:
             frame = node.frame(future=True)
             for inferred in node.expr.infer():
-                if inferred is util.Uninferable:
+                if isinstance(inferred, util.UninferableBase):
                     continue
                 try:
                     # pylint: disable=unidiomatic-typecheck # We want a narrow check on the
@@ -255,10 +255,7 @@ def delayed_assattr(self, node: nodes.AssignAttr) -> None:
                         # Const, Tuple or other containers that inherit from
                         # `Instance`
                         continue
-                    elif (
-                        isinstance(inferred, bases.Proxy)
-                        or inferred is util.Uninferable
-                    ):
+                    elif isinstance(inferred, (bases.Proxy, util.UninferableBase)):
                         continue
                     elif inferred.is_function:
                         iattrs = inferred.instance_attrs

astroid/constraint.py

@@ -74,7 +74,7 @@ def match(
     def satisfied_by(self, inferred: InferenceResult) -> bool:
         """Return True if this constraint is satisfied by the given inferred value."""
         # Assume true if uninferable
-        if inferred is util.Uninferable:
+        if isinstance(inferred, util.UninferableBase):
             return True
 
         # Return the XOR of self.negate and matches(inferred, self.CONST_NONE)