From 7d6713a46d30f51014632f74c13667d42bfa783a Mon Sep 17 00:00:00 2001
From: Yannick Jadoul <yannick.jadoul@belgacom.net>
Date: Mon, 2 Nov 2020 18:39:40 +0100
Subject: [PATCH] Use weakref to clean up captured function object in
 def_buffer (#2634)

---
 include/pybind11/pybind11.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index fa98f7c18..761f2a717 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -1315,7 +1315,8 @@ public:
         return *this;
     }
 
-    template <typename Func> class_& def_buffer(Func &&func) {
+    template <typename Func>
+    class_& def_buffer(Func &&func) {
         struct capture { Func func; };
         auto *ptr = new capture { std::forward<Func>(func) };
         install_buffer_funcs([](PyObject *obj, void *ptr) -> buffer_info* {
@@ -1324,6 +1325,10 @@ public:
                 return nullptr;
             return new buffer_info(((capture *) ptr)->func(caster));
         }, ptr);
+        weakref(m_ptr, cpp_function([ptr](handle wr) {
+            delete ptr;
+            wr.dec_ref();
+        })).release();
         return *this;
     }