From e5afd0ab99847f3d3083d4522243f1c717c93ba0 Mon Sep 17 00:00:00 2001
From: David Robertson <davidr@element.io>
Date: Tue, 21 Mar 2023 22:23:08 +0000
Subject: [PATCH 1/2] Make event objects unhashable

Generally speaking one should look up an event by its id. Otherwise
we'll fall back to `object.__hash__` (the instance's address, under
CPython) which is probably not what you want.

Noticed in #15240.
---
 synapse/events/__init__.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index 91118a8d847f..d3cec6412aa2 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -24,6 +24,7 @@
     Generic,
     Iterable,
     List,
+    NoReturn,
     Optional,
     Sequence,
     Tuple,
@@ -338,6 +339,9 @@ def __init__(
     type: DictProperty[str] = DictProperty("type")
     user_id: DictProperty[str] = DictProperty("sender")
 
+    def __hash__(self) -> NoReturn:
+        raise NotImplementedError()
+
     @property
     def event_id(self) -> str:
         raise NotImplementedError()

From 39d98249f4d6482c82bbbbaa2fa918ec5282e463 Mon Sep 17 00:00:00 2001
From: David Robertson <davidr@element.io>
Date: Tue, 21 Mar 2023 22:31:39 +0000
Subject: [PATCH 2/2] Changelog

---
 changelog.d/15305.misc | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/15305.misc

diff --git a/changelog.d/15305.misc b/changelog.d/15305.misc
new file mode 100644
index 000000000000..7d13682ce6ff
--- /dev/null
+++ b/changelog.d/15305.misc
@@ -0,0 +1 @@
+Make EventBase unhashable.