Create a NamedTuple instance for NamedTuples

Author: DanielNoord

ChangeLog

@@ -60,6 +60,9 @@ Release date: TBA
 * On Python versions >= 3.9, ``astroid`` now understands subscripting
   builtin classes such as ``enumerate`` or ``staticmethod``.
 
+* Instances of NamedTuples both from typing and collections will now be cast to a
+  NamedTuple instance. This instance proxies the definition of that NamedTuple.
+
 * Fixed inference of ``Enums`` when they are imported under an alias.
 
   Closes PyCQA/pylint#5776

astroid/bases.py

@@ -621,3 +621,7 @@ def __repr__(self):
 
     def __str__(self):
         return f"AsyncGenerator({self._proxied.name})"
+
+
+class NamedTuple(BaseInstance):
+    """Special node representing a NamedTuple instance"""

astroid/brain/brain_namedtuple_enum.py

@@ -186,21 +186,30 @@ def infer_named_tuple(
     node: nodes.Call, context: InferenceContext | None = None
 ) -> Iterator[nodes.ClassDef]:
     """Specific inference function for namedtuple Call node"""
-    tuple_base_name = nodes.Name(name="tuple", parent=node.root())
-    class_node, name, attributes = infer_func_form(
-        node, tuple_base_name, context=context
-    )
+    # Infer which type of NamedTuple we're dealing with (typing or collections)
+    inferred_namedtuple_call = next(node.func.infer())
+    base_names = [
+        nodes.Name(name="tuple", parent=node.root()),
+        nodes.Name(
+            name=inferred_namedtuple_call.name,
+            parent=inferred_namedtuple_call.root(),
+        ),
+    ]
+
+    class_node, name, attributes = infer_func_form(node, base_names, context=context)
     call_site = arguments.CallSite.from_call(node, context=context)
-    node = extract_node("import collections; collections.namedtuple")
-    try:
 
-        func = next(node.infer())
-    except StopIteration as e:
-        raise InferenceError(node=node) from e
     try:
-        rename = next(call_site.infer_argument(func, "rename", context)).bool_value()
+        rename = next(
+            call_site.infer_argument(inferred_namedtuple_call, "rename", context)
+        ).bool_value()
     except (InferenceError, StopIteration):
         rename = False
+    # If inferred_namedtuple_call is the ClassDef of typing.NamedTuple
+    # infer_argument will raise AttributeError
+    # TODO: See if this exception can be prevented
+    except AttributeError:
+        rename = False
 
     try:
         attributes = _check_namedtuple_attributes(name, attributes, rename)
@@ -331,7 +340,7 @@ def value(self):
         __members__ = ['']
     """
     )
-    class_node = infer_func_form(node, enum_meta, context=context, enum=True)[0]
+    class_node = infer_func_form(node, [enum_meta], context=context, enum=True)[0]
     return iter([class_node.instantiate_class()])
 
 
@@ -509,9 +518,11 @@ def infer_typing_namedtuple_function(node, context=None):
 def infer_typing_namedtuple(
     node: nodes.Call, context: InferenceContext | None = None
 ) -> Iterator[nodes.ClassDef]:
-    """Infer a typing.NamedTuple(...) call."""
-    # This is essentially a namedtuple with different arguments
-    # so we extract the args and infer a named tuple.
+    """Infer a typing.NamedTuple(...) call.
+
+    We do some premature checking of the node to see if we don't run into any unexpected
+    values.
+    """
     try:
         func = next(node.func.infer())
     except (InferenceError, StopIteration) as exc:

astroid/const.py

@@ -6,6 +6,11 @@
 import sys
 from pathlib import Path
 
+if sys.version_info >= (3, 8):
+    from typing import Final
+else:
+    from typing_extensions import Final
+
 PY38 = sys.version_info[:2] == (3, 8)
 PY38_PLUS = sys.version_info >= (3, 8)
 PY39_PLUS = sys.version_info >= (3, 9)
@@ -33,3 +38,6 @@ class Context(enum.Enum):
 
 ASTROID_INSTALL_DIRECTORY = Path(__file__).parent
 BRAIN_MODULES_DIRECTORY = ASTROID_INSTALL_DIRECTORY / "brain"
+
+NAMEDTUPLE_BASENAMES: Final[frozenset[str]] = frozenset(("namedtuple", "NamedTuple"))
+"""Const used to identify namedtuples in the basenames of subclasses"""

astroid/filter_statements.py

@@ -78,27 +78,27 @@ def _filter_stmts(base_node: nodes.NodeNG, stmts, frame, offset):
         #
         # def test(b=1):
         #     ...
+        #
+        # If the frame is already a Module we don't need to go up anymore
         if (
-            base_node.parent
+            not isinstance(myframe, nodes.Module)
+            and base_node.parent
             and base_node.statement(future=True) is myframe
             and myframe.parent
         ):
             myframe = myframe.parent.frame()
 
+    # We can use line filtering if we are in the same frame.
+    # mylineno is 0 by default to skip if we can't determine lineno
+    # or if we are at the module level. lineno information is (for example)
+    # missing for nodes inserted for living objects.
+    mylineno = 0
     mystmt: nodes.Statement | None = None
-    if base_node.parent:
+    if base_node.parent and not isinstance(base_node.parent, nodes.Module):
         mystmt = base_node.statement(future=True)
-
-    # line filtering if we are in the same frame
-    #
-    # take care node may be missing lineno information (this is the case for
-    # nodes inserted for living objects)
-    if myframe is frame and mystmt and mystmt.fromlineno is not None:
-        assert mystmt.fromlineno is not None, mystmt
-        mylineno = mystmt.fromlineno + offset
-    else:
-        # disabling lineno filtering
-        mylineno = 0
+        if myframe is frame and mystmt.fromlineno is not None:
+            assert mystmt.fromlineno is not None, mystmt
+            mylineno = mystmt.fromlineno + offset
 
     _stmts = []
     _stmt_parents = []

astroid/nodes/scoped_nodes/scoped_nodes.py

@@ -20,8 +20,8 @@
 
 from astroid import bases
 from astroid import decorators as decorators_mod
-from astroid import util
-from astroid.const import IS_PYPY, PY38, PY38_PLUS, PY39_PLUS
+from astroid import mixins, util
+from astroid.const import IS_PYPY, NAMEDTUPLE_BASENAMES, PY38, PY38_PLUS, PY39_PLUS
 from astroid.context import (
     CallContext,
     InferenceContext,
@@ -2521,6 +2521,8 @@ def instantiate_class(self):
                 return objects.ExceptionInstance(self)
         except MroError:
             pass
+        if any(i in NAMEDTUPLE_BASENAMES for i in self.basenames):
+            return bases.NamedTuple(self)
         return bases.Instance(self)
 
     def getattr(self, name, context=None, class_context=True):

tests/unittest_brain.py

@@ -1502,7 +1502,8 @@ class X(NamedTuple("X", [("a", int), ("b", str), ("c", bytes)])):
         """
         )
         self.assertEqual(
-            [anc.name for anc in klass.ancestors()], ["X", "tuple", "object"]
+            [anc.name for anc in klass.ancestors()],
+            ["X", "tuple", "object", "NamedTuple"],
         )
         for anc in klass.ancestors():
             self.assertFalse(anc.parent is None)
@@ -1611,7 +1612,7 @@ class Example(NamedTuple):
         """
         )
         inferred = next(result.infer())
-        self.assertIsInstance(inferred, astroid.Instance)
+        self.assertIsInstance(inferred, bases.NamedTuple)
 
         class_attr = inferred.getattr("CLASS_ATTR")[0]
         self.assertIsInstance(class_attr, astroid.AssignName)
@@ -1784,7 +1785,7 @@ def test_typing_namedtuple_dont_crash_on_no_fields(self) -> None:
         """
         )
         inferred = next(node.infer())
-        self.assertIsInstance(inferred, astroid.Instance)
+        self.assertIsInstance(inferred, bases.NamedTuple)
 
     @test_utils.require_version("3.8")
     def test_typed_dict(self):
@@ -3131,7 +3132,7 @@ def test_http_client_brain() -> None:
     """
     )
     inferred = next(node.infer())
-    assert isinstance(inferred, astroid.Instance)
+    assert isinstance(inferred, bases.NamedTuple)
 
 
 def test_http_status_brain() -> None:

tests/unittest_inference.py

@@ -17,7 +17,7 @@
 
 import pytest
 
-from astroid import Slice, arguments
+from astroid import Slice, arguments, bases
 from astroid import decorators as decoratorsmod
 from astroid import helpers, nodes, objects, test_utils, util
 from astroid.arguments import CallSite
@@ -2193,8 +2193,8 @@ def collections(self):
 
         """
         ast = parse(code, __name__)
-        bases = ast["Second"].bases[0]
-        inferred = next(bases.infer())
+        base_classes = ast["Second"].bases[0]
+        inferred = next(base_classes.infer())
         self.assertTrue(inferred)
         self.assertIsInstance(inferred, nodes.ClassDef)
         self.assertEqual(inferred.qname(), "collections.Counter")
@@ -6249,7 +6249,7 @@ def test_inferaugassign_picking_parent_instead_of_stmt() -> None:
     # as a string.
     node = extract_node(code)
     inferred = next(node.infer())
-    assert isinstance(inferred, Instance)
+    assert isinstance(inferred, bases.NamedTuple)
     assert inferred.name == "SomeClass"
 
 

tests/unittest_object_model.py

@@ -8,7 +8,7 @@
 import pytest
 
 import astroid
-from astroid import builder, nodes, objects, test_utils, util
+from astroid import bases, builder, nodes, objects, test_utils, util
 from astroid.const import PY311_PLUS
 from astroid.exceptions import InferenceError
 
@@ -203,9 +203,9 @@ class C(A): pass
         called_mro = next(ast_nodes[5].infer())
         self.assertEqual(called_mro.elts, mro.elts)
 
-        bases = next(ast_nodes[6].infer())
-        self.assertIsInstance(bases, astroid.Tuple)
-        self.assertEqual([cls.name for cls in bases.elts], ["object"])
+        bases_classes = next(ast_nodes[6].infer())
+        self.assertIsInstance(bases_classes, astroid.Tuple)
+        self.assertEqual([cls.name for cls in bases_classes.elts], ["object"])
 
         cls = next(ast_nodes[7].infer())
         self.assertIsInstance(cls, astroid.ClassDef)
@@ -694,7 +694,7 @@ def foo():
         self.assertIsInstance(wrapped, astroid.FunctionDef)
         self.assertEqual(wrapped.name, "foo")
         cache_info = next(ast_nodes[2].infer())
-        self.assertIsInstance(cache_info, astroid.Instance)
+        self.assertIsInstance(cache_info, bases.NamedTuple)
 
 
 if __name__ == "__main__":