From a9d84f4e44783bc75dd931093339636732bfbf6c Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Tue, 25 Sep 2018 10:43:39 +0100
Subject: [PATCH 1/2] We require attrs 16.0.0

Ref: https://github.com/matrix-org/synapse/issues/3945
---
 synapse/python_dependencies.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 0d8de600c..c779f69fa 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -58,7 +58,9 @@ REQUIREMENTS = {
     "phonenumbers>=8.2.0": ["phonenumbers"],
     "six": ["six"],
     "prometheus_client": ["prometheus_client"],
-    "attrs": ["attr"],
+
+    # we use attr.s(slots), which arrived in 16.0.0
+    "attrs>=16.0.0": ["attr>=16.0.0"],
     "netaddr>=0.7.18": ["netaddr"],
 }
 

From 45a1053d447903aae9b75d9a86016e71034917b9 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Tue, 25 Sep 2018 10:45:34 +0100
Subject: [PATCH 2/2] changelog

---
 changelog.d/3947.misc | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/3947.misc

diff --git a/changelog.d/3947.misc b/changelog.d/3947.misc
new file mode 100644
index 000000000..5a9a22bed
--- /dev/null
+++ b/changelog.d/3947.misc
@@ -0,0 +1 @@
+Require attrs 16.0.0 or later