fix slots calculation

Author: JelleZijlstra

mypy/checkmember.py

@@ -1484,13 +1484,7 @@ def analyze_decorator_or_funcbase_access(
     if isinstance(defn, Decorator):
         return analyze_var(name, defn.var, itype, mx)
     typ = function_type(defn, mx.chk.named_type("builtins.function"))
-    is_trivial_self = False
-    if isinstance(defn, Decorator):
-        # Use fast path if there are trivial decorators like @classmethod or @property
-        is_trivial_self = defn.func.is_trivial_self and not defn.decorators
-    elif isinstance(defn, (FuncDef, OverloadedFuncDef)):
-        is_trivial_self = defn.is_trivial_self
-    if is_trivial_self:
+    if isinstance(defn, (FuncDef, OverloadedFuncDef)) and defn.is_trivial_self:
         return bind_self_fast(typ, mx.self_type)
     typ = check_self_arg(typ, mx.self_type, defn.is_class, mx.context, name, mx.msg)
     return bind_self(typ, original_type=mx.self_type, is_classmethod=defn.is_class)

mypy/typeops.py

@@ -1257,7 +1257,19 @@ def named_type(fullname: str) -> Instance:
 
 def _is_disjoint_base(info: TypeInfo) -> bool:
     # It either has the @disjoint_base decorator or defines nonempty __slots__.
-    return info.is_disjoint_base or bool(info.slots)
+    if info.is_disjoint_base:
+        return True
+    if not info.slots:
+        return False
+    own_slots = {
+        slot
+        for slot in info.slots
+        if not any(
+            base_info.type.slots is not None and slot in base_info.type.slots
+            for base_info in info.bases
+        )
+    }
+    return bool(own_slots)
 
 
 def _get_disjoint_base_of(instance: Instance) -> TypeInfo | None: