Remove all uses of PYBIND11_SMART_HOLDER_ENABLED under include/pybind11

include/pybind11/cast.h

@@ -836,8 +836,6 @@ protected:
     holder_type holder;
 };
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
 template <typename, typename SFINAE = void>
 struct copyable_holder_caster_shared_ptr_with_smart_holder_support_enabled : std::true_type {};
 
@@ -928,13 +926,13 @@ protected:
             return;
         }
         throw cast_error("Unable to cast from non-held to held instance (T& to Holder<T>) "
-#    if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
+#if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
                          "(#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for "
                          "type information)");
-#    else
+#else
                          "of type '"
                          + type_id<std::shared_ptr<type>>() + "''");
-#    endif
+#endif
     }
 
     template <typename T = std::shared_ptr<type>,
@@ -968,8 +966,6 @@ protected:
     std::shared_ptr<type> shared_ptr_storage;
 };
 
-#endif // PYBIND11_SMART_HOLDER_ENABLED
-
 /// Specialize for the common std::shared_ptr, so users don't need to
 template <typename T>
 class type_caster<std::shared_ptr<T>> : public copyable_holder_caster<T, std::shared_ptr<T>> {};
@@ -990,8 +986,6 @@ struct move_only_holder_caster {
     static constexpr auto name = type_caster_base<type>::name;
 };
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
 template <typename, typename SFINAE = void>
 struct move_only_holder_caster_unique_ptr_with_smart_holder_support_enabled : std::true_type {};
 
@@ -1129,8 +1123,6 @@ public:
     std::shared_ptr<std::unique_ptr<type, deleter>> unique_ptr_storage;
 };
 
-#endif // PYBIND11_SMART_HOLDER_ENABLED
-
 template <typename type, typename deleter>
 class type_caster<std::unique_ptr<type, deleter>>
     : public move_only_holder_caster<type, std::unique_ptr<type, deleter>> {};
@@ -1169,10 +1161,8 @@ struct is_holder_type
 template <typename base, typename deleter>
 struct is_holder_type<base, std::unique_ptr<base, deleter>> : std::true_type {};
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
 template <typename base>
 struct is_holder_type<base, smart_holder> : std::true_type {};
-#endif
 
 #ifdef PYBIND11_DISABLE_HANDLE_TYPE_NAME_DEFAULT_IMPLEMENTATION // See PR #4888
 

include/pybind11/detail/init.h

@@ -198,8 +198,6 @@ void construct(value_and_holder &v_h, Alias<Class> &&result, bool) {
     v_h.value_ptr() = new Alias<Class>(std::move(result));
 }
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
 template <typename T, typename D>
 smart_holder init_smart_holder_from_unique_ptr(std::unique_ptr<T, D> &&unq_ptr,
                                                bool void_cast_raw_ptr) {
@@ -268,8 +266,6 @@ void construct(value_and_holder &v_h,
     v_h.type->init_instance(v_h.inst, &smhldr);
 }
 
-#endif // PYBIND11_SMART_HOLDER_ENABLED
-
 // Implementing class for py::init<...>()
 template <typename... Args>
 struct constructor {

include/pybind11/detail/type_caster_base.h

@@ -511,8 +511,6 @@ inline PyThreadState *get_thread_state_unchecked() {
 void keep_alive_impl(handle nurse, handle patient);
 inline PyObject *make_new_instance(PyTypeObject *type);
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
 // PYBIND11:REMINDER: Needs refactoring of existing pybind11 code.
 inline bool deregister_instance(instance *self, void *valptr, const type_info *tinfo);
 
@@ -868,8 +866,6 @@ struct load_helper : value_and_holder_helper {
 
 PYBIND11_NAMESPACE_END(smart_holder_type_caster_support)
 
-#endif // PYBIND11_SMART_HOLDER_ENABLED
-
 class type_caster_generic {
 public:
     PYBIND11_NOINLINE explicit type_caster_generic(const std::type_info &type_info)
@@ -974,7 +970,6 @@ public:
 
     // Base methods for generic caster; there are overridden in copyable_holder_caster
     void load_value(value_and_holder &&v_h) {
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
         if (typeinfo->holder_enum_v == detail::holder_enum_t::smart_holder) {
             smart_holder_type_caster_support::value_and_holder_helper v_h_helper;
             v_h_helper.loaded_v_h = v_h;
@@ -984,7 +979,6 @@ public:
                 return;
             }
         }
-#endif
         auto *&vptr = v_h.value_ptr();
         // Lazy allocation for unallocated values:
         if (vptr == nullptr) {

include/pybind11/detail/using_smart_holder.h

@@ -5,29 +5,18 @@
 #pragma once
 
 #include "common.h"
-#include "internals.h"
+#include "struct_smart_holder.h"
 
 #include <type_traits>
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-#    include "struct_smart_holder.h"
-#endif
-
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
 using pybindit::memory::smart_holder;
-#endif
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
 template <typename H>
 using is_smart_holder = std::is_same<H, smart_holder>;
-#else
-template <typename>
-struct is_smart_holder : std::false_type {};
-#endif
 
 PYBIND11_NAMESPACE_END(detail)
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/pybind11.h

@@ -1663,8 +1663,6 @@ PYBIND11_NAMESPACE_END(detail)
 template <typename T, typename D, typename SFINAE = void>
 struct property_cpp_function : detail::property_cpp_function_classic<T, D> {};
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
 PYBIND11_NAMESPACE_BEGIN(detail)
 
 template <typename T, typename D, typename SFINAE = void>
@@ -1842,9 +1840,7 @@ struct property_cpp_function<
         detail::both_t_and_d_use_type_caster_base<T, typename D::element_type>>::value>>
     : detail::property_cpp_function_sh_unique_ptr_member<T, D> {};
 
-#endif // PYBIND11_SMART_HOLDER_ENABLED
-
-#if defined(PYBIND11_USE_SMART_HOLDER_AS_DEFAULT) && defined(PYBIND11_SMART_HOLDER_ENABLED)
+#if defined(PYBIND11_USE_SMART_HOLDER_AS_DEFAULT)
 // NOTE: THIS IS MEANT FOR STRESS-TESTING ONLY!
 //       As of PR #5257, for production use, there is no longer a strong reason to make
 //       smart_holder the default holder:
@@ -1911,7 +1907,6 @@ public:
         // A more fitting name would be uses_unique_ptr_holder.
         record.default_holder = detail::is_instantiation<std::unique_ptr, holder_type>::value;
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
         if (detail::is_instantiation<std::unique_ptr, holder_type>::value) {
             record.holder_enum_v = detail::holder_enum_t::std_unique_ptr;
         } else if (detail::is_instantiation<std::shared_ptr, holder_type>::value) {
@@ -1921,7 +1916,6 @@ public:
         } else {
             record.holder_enum_v = detail::holder_enum_t::custom_holder;
         }
-#endif
 
         set_operator_new<type>(&record);
 
@@ -2263,8 +2257,6 @@ private:
         init_holder(inst, v_h, (const holder_type *) holder_ptr, v_h.value_ptr<type>());
     }
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
     template <typename WrappedType>
     static bool try_initialization_using_shared_from_this(holder_type *, WrappedType *, ...) {
         return false;
@@ -2324,8 +2316,6 @@ private:
         v_h.set_holder_constructed();
     }
 
-#endif // PYBIND11_SMART_HOLDER_ENABLED
-
     // Deallocates an instance; via holder, if constructed; otherwise via operator delete.
     // NOTE: The Python error indicator needs to cleared BEFORE this function is called.
     // This is because we could be deallocating while cleaning up after a Python exception.
@@ -2391,8 +2381,6 @@ private:
     }
 };
 
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
 // Supports easier switching between py::class_<T> and py::class_<T, py::smart_holder>:
 // users can simply replace the `_` in `class_` with `h` or vice versa.
 template <typename type_, typename... options>
@@ -2401,8 +2389,6 @@ public:
     using class_<type_, smart_holder, options...>::class_;
 };
 
-#endif
-
 /// Binds an existing constructor taking arguments Args...
 template <typename... Args>
 detail::initimpl::constructor<Args...> init() {

include/pybind11/trampoline_self_life_support.h

@@ -4,13 +4,9 @@
 
 #pragma once
 
-#include "detail/internals.h"
-
-#ifdef PYBIND11_SMART_HOLDER_ENABLED
-
-#    include "detail/common.h"
-#    include "detail/using_smart_holder.h"
-#    include "detail/value_and_holder.h"
+#include "detail/common.h"
+#include "detail/using_smart_holder.h"
+#include "detail/value_and_holder.h"
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
@@ -62,5 +58,3 @@ struct trampoline_self_life_support {
 };
 
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
-
-#endif // PYBIND11_SMART_HOLDER_ENABLED