Fix crash inferring on NewType named with f-string (#1400)

Author: jacobtylerwalls

ChangeLog

@@ -25,6 +25,10 @@ Release date: TBA
 
   Closes PyCQA/pylint#5771
 
+* Fixed a crash inferring on a ``NewType`` named with an f-string.
+
+  Closes PyCQA/pylint#5770
+
 * Add support for [attrs v21.3.0](https://github.com/python-attrs/attrs/releases/tag/21.3.0) which
   added a new `attrs` module alongside the existing `attr`.
 

astroid/brain/brain_typing.py

@@ -31,6 +31,7 @@
     Attribute,
     Call,
     Const,
+    JoinedStr,
     Name,
     NodeNG,
     Subscript,
@@ -128,6 +129,9 @@ def infer_typing_typevar_or_newtype(node, context_itton=None):
         raise UseInferenceDefault
     if not node.args:
         raise UseInferenceDefault
+    # Cannot infer from a dynamic class name (f-string)
+    if isinstance(node.args[0], JoinedStr):
+        raise UseInferenceDefault
 
     typename = node.args[0].as_string().strip("'")
     node = extract_node(TYPING_TYPE_TEMPLATE.format(typename))

tests/unittest_brain.py

@@ -57,7 +57,11 @@
 from astroid import MANAGER, bases, builder, nodes, objects, test_utils, util
 from astroid.bases import Instance
 from astroid.const import PY37_PLUS
-from astroid.exceptions import AttributeInferenceError, InferenceError
+from astroid.exceptions import (
+    AttributeInferenceError,
+    InferenceError,
+    UseInferenceDefault,
+)
 from astroid.nodes.node_classes import Const
 from astroid.nodes.scoped_nodes import ClassDef
 
@@ -1660,6 +1664,19 @@ def test_typing_types(self) -> None:
             inferred = next(node.infer())
             self.assertIsInstance(inferred, nodes.ClassDef, node.as_string())
 
+    def test_typing_type_without_tip(self):
+        """Regression test for https://github.com/PyCQA/pylint/issues/5770"""
+        node = builder.extract_node(
+            """
+        from typing import NewType
+
+        def make_new_type(t):
+            new_type = NewType(f'IntRange_{t}', t) #@
+        """
+        )
+        with self.assertRaises(UseInferenceDefault):
+            astroid.brain.brain_typing.infer_typing_typevar_or_newtype(node.value)
+
     def test_namedtuple_nested_class(self):
         result = builder.extract_node(
             """