clearly error out on older setuptools (#4000)

* clearly error out on older setuptools

* use the right thing

1 files changed, 10 insertions, 0 deletions

diff --git a/setup.py b/setup.py
index 598643b6..2f32c766 100644
--- a/setup.py
+++ b/setup.py
@@ -14,11 +14,21 @@ from distutils.command.build import build
 
 import pkg_resources
 
+import setuptools
 from setuptools import find_packages, setup
 from setuptools.command.install import install
 from setuptools.command.test import test
 
 
+if (
+    pkg_resources.parse_version(setuptools.__version__) <
+    pkg_resources.parse_version("18.5")
+):
+    raise RuntimeError(
+        "cryptography requires setuptools 18.5 or newer, please upgrade to a "
+        "newer version of setuptools"
+    )
+
 base_dir = os.path.dirname(__file__)
 src_dir = os.path.join(base_dir, "src")