Renaming is_smart_holder_type_caster_base_tag -> smart_holder_type_caster_base_tag for simplicity.

include/pybind11/cast.h

@@ -68,7 +68,7 @@ using make_caster = type_caster<intrinsic_t<type>>;
 template <typename T>
 struct type_uses_smart_holder_type_caster {
     static constexpr bool value
-        = std::is_base_of<is_smart_holder_type_caster_base_tag, make_caster<T>>::value;
+        = std::is_base_of<smart_holder_type_caster_base_tag, make_caster<T>>::value;
 };
 // clang-format off
 

include/pybind11/detail/smart_holder_sfinae_hooks_only.h

@@ -20,7 +20,7 @@ template <typename T>
 struct is_smart_holder_type : std::false_type {};
 
 // Tag to be used as base class, inspected by type_uses_smart_holder_type_caster<T> test.
-struct is_smart_holder_type_caster_base_tag {};
+struct smart_holder_type_caster_base_tag {};
 
 template <typename T>
 struct type_uses_smart_holder_type_caster;

include/pybind11/detail/smart_holder_type_casters.h

@@ -239,7 +239,7 @@ public:
 };
 // clang-format on
 
-struct smart_holder_type_caster_class_hooks : is_smart_holder_type_caster_base_tag {
+struct smart_holder_type_caster_class_hooks : smart_holder_type_caster_base_tag {
     static decltype(&modified_type_caster_generic_load_impl::local_load)
     get_local_load_function_ptr() {
         return &modified_type_caster_generic_load_impl::local_load;