From 383486c616d0e43ea68f9044ffc45b429e4c6ba5 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Wed, 20 Aug 2025 15:36:36 -0700
Subject: [PATCH 1/2] stubtest: do not require @disjoint_base if there are
 __slots__

---
 mypy/stubtest.py          |  4 +++-
 mypy/test/teststubtest.py | 13 +++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/mypy/stubtest.py b/mypy/stubtest.py
index 43da0518b3f9..e90e072615a5 100644
--- a/mypy/stubtest.py
+++ b/mypy/stubtest.py
@@ -510,7 +510,9 @@ def _verify_disjoint_base(
     if stub.is_final:
         return
     is_disjoint_runtime = _is_disjoint_base(runtime)
-    if is_disjoint_runtime and not stub.is_disjoint_base:
+    # Don't complain about missing @disjoint_base if there are __slots__, because
+    # in that case we can infer that it's a disjoint base.
+    if is_disjoint_runtime and not stub.is_disjoint_base and stub.slots is None:
         yield Error(
             object_path,
             "is a disjoint base at runtime, but isn't marked with @disjoint_base in the stub",
diff --git a/mypy/test/teststubtest.py b/mypy/test/teststubtest.py
index 69e2abe62f85..5bcf4a36bbc5 100644
--- a/mypy/test/teststubtest.py
+++ b/mypy/test/teststubtest.py
@@ -1430,6 +1430,19 @@ class BytesEnum(bytes, enum.Enum):
             """,
             error=None,
         )
+        yield Case(
+            stub="""
+            class HasSlotsAndNothingElse:
+                __slots__ = ("x",)
+                x: int
+            """,
+            runtime="""
+            class HasSlotsAndNothingElse:
+                __slots__ = ("x",)
+                x: int
+            """,
+            error=None,
+        )
 
     @collect_cases
     def test_decorator(self) -> Iterator[Case]:

From c4fbcbd7110d63dae9ad8de5a4dd27f1f310540e Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Wed, 20 Aug 2025 17:37:43 -0700
Subject: [PATCH 2/2] fix with slots

---
 mypy/stubtest.py          |  2 +-
 mypy/test/teststubtest.py | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/mypy/stubtest.py b/mypy/stubtest.py
index e90e072615a5..f560049f2ec8 100644
--- a/mypy/stubtest.py
+++ b/mypy/stubtest.py
@@ -512,7 +512,7 @@ def _verify_disjoint_base(
     is_disjoint_runtime = _is_disjoint_base(runtime)
     # Don't complain about missing @disjoint_base if there are __slots__, because
     # in that case we can infer that it's a disjoint base.
-    if is_disjoint_runtime and not stub.is_disjoint_base and stub.slots is None:
+    if is_disjoint_runtime and not stub.is_disjoint_base and not runtime.__dict__.get("__slots__"):
         yield Error(
             object_path,
             "is a disjoint base at runtime, but isn't marked with @disjoint_base in the stub",
diff --git a/mypy/test/teststubtest.py b/mypy/test/teststubtest.py
index 5bcf4a36bbc5..e6bc2c818164 100644
--- a/mypy/test/teststubtest.py
+++ b/mypy/test/teststubtest.py
@@ -1435,11 +1435,23 @@ class BytesEnum(bytes, enum.Enum):
             class HasSlotsAndNothingElse:
                 __slots__ = ("x",)
                 x: int
+
+            class HasInheritedSlots(HasSlotsAndNothingElse):
+                pass
+
+            class HasEmptySlots:
+                __slots__ = ()
             """,
             runtime="""
             class HasSlotsAndNothingElse:
                 __slots__ = ("x",)
                 x: int
+
+            class HasInheritedSlots(HasSlotsAndNothingElse):
+                pass
+
+            class HasEmptySlots:
+                __slots__ = ()
             """,
             error=None,
         )