From 5b84e50dc0158474b4bd8f9dfc668e9e23852647 Mon Sep 17 00:00:00 2001
From: Erik Montnemery <erik@montnemery.com>
Date: Tue, 9 Jan 2024 19:16:45 +0100
Subject: [PATCH] Prevent overriding cached attribute as property (#107657)

* Prevent overriding cached attribute as property

* Remove debug
---
 homeassistant/helpers/entity.py |  4 ++++
 tests/helpers/test_entity.py    | 41 +++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/homeassistant/helpers/entity.py b/homeassistant/helpers/entity.py
index 743d3675a3b..1f3f96f300c 100644
--- a/homeassistant/helpers/entity.py
+++ b/homeassistant/helpers/entity.py
@@ -13,6 +13,7 @@ import logging
 import math
 import sys
 from timeit import default_timer as timer
+from types import FunctionType
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -374,6 +375,9 @@ class CachedProperties(type):
             # Check if an _attr_ class attribute exits and move it to __attr_. We check
             # __dict__ here because we don't care about _attr_ class attributes in parents.
             if attr_name in cls.__dict__:
+                attr = getattr(cls, attr_name)
+                if isinstance(attr, (FunctionType, property)):
+                    raise TypeError(f"Can't override {attr_name} in subclass")
                 setattr(cls, private_attr_name, getattr(cls, attr_name))
                 annotations = cls.__annotations__
                 if attr_name in annotations:
diff --git a/tests/helpers/test_entity.py b/tests/helpers/test_entity.py
index a18d8963947..2e2aac570ea 100644
--- a/tests/helpers/test_entity.py
+++ b/tests/helpers/test_entity.py
@@ -2039,6 +2039,47 @@ async def test_cached_entity_property_class_attribute(hass: HomeAssistant) -> No
         assert getattr(ent[1], property) == values[0]
 
 
+async def test_cached_entity_property_override(hass: HomeAssistant) -> None:
+    """Test overriding cached _attr_ raises."""
+
+    class EntityWithClassAttribute1(entity.Entity):
+        """A derived class which overrides an _attr_ from a parent."""
+
+        _attr_attribution: str
+
+    class EntityWithClassAttribute2(entity.Entity):
+        """A derived class which overrides an _attr_ from a parent."""
+
+        _attr_attribution = "blabla"
+
+    class EntityWithClassAttribute3(entity.Entity):
+        """A derived class which overrides an _attr_ from a parent."""
+
+        _attr_attribution: str = "blabla"
+
+    class EntityWithClassAttribute4(entity.Entity):
+        @property
+        def _attr_not_cached(self):
+            return "blabla"
+
+    class EntityWithClassAttribute5(entity.Entity):
+        def _attr_not_cached(self):
+            return "blabla"
+
+    with pytest.raises(TypeError):
+
+        class EntityWithClassAttribute6(entity.Entity):
+            @property
+            def _attr_attribution(self):
+                return "🤡"
+
+    with pytest.raises(TypeError):
+
+        class EntityWithClassAttribute7(entity.Entity):
+            def _attr_attribution(self):
+                return "🤡"
+
+
 async def test_entity_report_deprecated_supported_features_values(
     caplog: pytest.LogCaptureFixture,
 ) -> None: