From 2ceb3f9c9f60212eb76c96c1aa83e3fb140ff7b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dani=C3=ABl=20van=20Noord?=
 <13665637+DanielNoord@users.noreply.github.com>
Date: Tue, 6 Sep 2022 11:20:07 +0200
Subject: [PATCH] Fix crash in ``dataclass`` brain

---
 ChangeLog                           |  3 +++
 astroid/brain/brain_dataclasses.py  |  4 +++-
 tests/unittest_brain_dataclasses.py | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index bdf36d531c..f655c16e64 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -17,6 +17,9 @@ What's New in astroid 2.12.7?
 =============================
 Release date: TBA
 
+* Fixed a crash in the ``dataclass`` brain for uninferable bases.
+
+  Closes PyCQA/pylint#7418
 
 
 What's New in astroid 2.12.6?
diff --git a/astroid/brain/brain_dataclasses.py b/astroid/brain/brain_dataclasses.py
index 6549300cf1..3c83a25986 100644
--- a/astroid/brain/brain_dataclasses.py
+++ b/astroid/brain/brain_dataclasses.py
@@ -231,7 +231,9 @@ def _generate_dataclass_init(
             assignments.append(assignment_str)
 
     try:
-        base: ClassDef = next(next(iter(node.bases)).infer())
+        base = next(next(iter(node.bases)).infer())
+        if not isinstance(base, ClassDef):
+            raise InferenceError
         base_init: FunctionDef | None = base.locals["__init__"][0]
     except (StopIteration, InferenceError, KeyError):
         base_init = None
diff --git a/tests/unittest_brain_dataclasses.py b/tests/unittest_brain_dataclasses.py
index ad2f648afa..492d9ea555 100644
--- a/tests/unittest_brain_dataclasses.py
+++ b/tests/unittest_brain_dataclasses.py
@@ -824,3 +824,26 @@ class Dee(Cee):
             "ee",
         ]
         assert [a.name for a in dee_init.args.kwonlyargs] == []
+
+
+def test_dataclass_with_unknown_base() -> None:
+    """Regression test for dataclasses with unknown base classes.
+
+    Reported in https://github.com/PyCQA/pylint/issues/7418
+    """
+    node = astroid.extract_node(
+        """
+    import dataclasses
+
+    from unknown import Unknown
+
+
+    @dataclasses.dataclass
+    class MyDataclass(Unknown):
+        pass
+
+    MyDataclass()
+    """
+    )
+
+    assert next(node.infer())