From 45e6e6f6eb8754f86ebe6886d39fc97addd13b5f Mon Sep 17 00:00:00 2001
From: Wenzel Jakob <wenzel.jakob@epfl.ch>
Date: Fri, 4 Nov 2016 11:06:22 +0100
Subject: [PATCH] add note about custom type casters (fixes #480)

---
 docs/advanced/cast/custom.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/docs/advanced/cast/custom.rst b/docs/advanced/cast/custom.rst
index 50b07db51..c854e7fcd 100644
--- a/docs/advanced/cast/custom.rst
+++ b/docs/advanced/cast/custom.rst
@@ -77,3 +77,9 @@ type is explicitly allowed.
             }
         };
     }} // namespace pybind11::detail
+
+.. warning::
+
+    When using custom type casters, it's important to declare them consistently
+    in every compilation unit of the Python extension module. Otherwise,
+    undefined behavior can ensue.