From 20ef96c87db22534730ed627a21496509fbd3ba5 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Sat, 19 Jun 2021 18:24:36 -0700
Subject: [PATCH] Disabling debugging call of `weak_from_this` for C++ < 17.

---
 include/pybind11/detail/smart_holder_poc.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/pybind11/detail/smart_holder_poc.h b/include/pybind11/detail/smart_holder_poc.h
index abb87827f..e83737e7b 100644
--- a/include/pybind11/detail/smart_holder_poc.h
+++ b/include/pybind11/detail/smart_holder_poc.h
@@ -64,8 +64,11 @@ inline int shared_from_this_status(...) { return 0; }
 
 template <typename AnyBaseOfT>
 inline int shared_from_this_status(const std::enable_shared_from_this<AnyBaseOfT> *ptr) {
+#if defined(__cpp_lib_enable_shared_from_this) && (!defined(_MSC_VER) || _MSC_VER >= 1912)
   if (ptr->weak_from_this().lock()) return 1;
   return -1;
+#endif
+  return 999;
 }
 
 struct smart_holder;