From 00a91571fbf3ed58746f67aa38d379afb9d3476e Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Sat, 29 Jun 2024 12:13:19 -0700
Subject: [PATCH] fix build failure by introducing init_instance()
 specialization for smart_holder (test fails)

---
 include/pybind11/pybind11.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index 3362b4d79..ef363a3ec 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -1954,6 +1954,9 @@ private:
     /// instance.  Should be called as soon as the `type` value_ptr is set for an instance.  Takes
     /// an optional pointer to an existing holder to use; if not specified and the instance is
     /// `.owned`, a new holder will be constructed to manage the value pointer.
+    template <typename H = holder_type,
+              detail::enable_if_t<!std::is_same<H, pybindit::memory::smart_holder>::value, int>
+              = 0>
     static void init_instance(detail::instance *inst, const void *holder_ptr) {
         auto v_h = inst->get_value_and_holder(detail::get_type_info(typeid(type)));
         if (!v_h.instance_registered()) {
@@ -1963,6 +1966,12 @@ private:
         init_holder(inst, v_h, (const holder_type *) holder_ptr, v_h.value_ptr<type>());
     }
 
+    template <typename H = holder_type,
+              detail::enable_if_t<std::is_same<H, pybindit::memory::smart_holder>::value, int> = 0>
+    static void init_instance(detail::instance * /*inst*/, const void * /*holder_ptr*/) {
+        // detail::type_caster<T>::template init_instance_for_type<T, A>(inst, holder_ptr);
+    }
+
     /// Deallocates an instance; via holder, if constructed; otherwise via operator delete.
     static void dealloc(detail::value_and_holder &v_h) {
         // We could be deallocating because we are cleaning up after a Python exception.