From 63044cc19950acd6ffe5390e1a25f6973280fb4c Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Fri, 12 Jul 2024 08:26:34 -0700
Subject: [PATCH] Bring in `default_holder_type` from smart_holder branch
 including using it in pybind11/stl_bind.h

---
 include/pybind11/cast.h     | 6 ++++++
 include/pybind11/pybind11.h | 3 +++
 include/pybind11/stl_bind.h | 4 ++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index 893c25cc0..b444c83ca 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -1111,6 +1111,12 @@ template <typename base, typename holder>
 struct is_holder_type
     : std::is_base_of<detail::type_caster_holder<base, holder>, detail::type_caster<holder>> {};
 
+// Specializations for always-supported holders:
+template <typename base, typename deleter>
+struct is_holder_type<base, std::unique_ptr<base, deleter>> : std::true_type {};
+template <typename base>
+struct is_holder_type<base, pybindit::memory::smart_holder> : std::true_type {};
+
 #ifdef PYBIND11_DISABLE_HANDLE_TYPE_NAME_DEFAULT_IMPLEMENTATION // See PR #4888
 
 // This leads to compilation errors if a specialization is missing.
diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index 71220e4f1..ead4006ef 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -1775,6 +1775,9 @@ struct property_cpp_function<
     }
 };
 
+template <typename>
+using default_holder_type = pybindit::memory::smart_holder;
+
 template <typename type_, typename... options>
 class class_ : public detail::generic_type {
     template <typename T>
diff --git a/include/pybind11/stl_bind.h b/include/pybind11/stl_bind.h
index 66c452ea7..a04e16864 100644
--- a/include/pybind11/stl_bind.h
+++ b/include/pybind11/stl_bind.h
@@ -487,7 +487,7 @@ PYBIND11_NAMESPACE_END(detail)
 //
 // std::vector
 //
-template <typename Vector, typename holder_type = std::unique_ptr<Vector>, typename... Args>
+template <typename Vector, typename holder_type = default_holder_type<Vector>, typename... Args>
 class_<Vector, holder_type> bind_vector(handle scope, std::string const &name, Args &&...args) {
     using Class_ = class_<Vector, holder_type>;
 
@@ -696,7 +696,7 @@ struct ItemsViewImpl : public detail::items_view {
 
 PYBIND11_NAMESPACE_END(detail)
 
-template <typename Map, typename holder_type = std::unique_ptr<Map>, typename... Args>
+template <typename Map, typename holder_type = default_holder_type<Map>, typename... Args>
 class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args &&...args) {
     using KeyType = typename Map::key_type;
     using MappedType = typename Map::mapped_type;