replacing std::any with void_ptr_with_type_info

include/pybind11/attr.h

@@ -245,7 +245,7 @@ struct type_record {
     void *(*operator_new)(size_t) = nullptr;
 
     /// Function pointer to class_<..>::init_instance
-    void (*init_instance)(instance *, std::any) = nullptr;
+    void (*init_instance)(instance *, void_ptr_with_type_info) = nullptr;
 
     /// Function pointer to class_<..>::dealloc
     void (*dealloc)(detail::value_and_holder &) = nullptr;

include/pybind11/cast.h

@@ -14,7 +14,6 @@
 #include "detail/typeid.h"
 #include "detail/descr.h"
 #include "detail/internals.h"
-#include <any>
 #include <array>
 #include <limits>
 #include <tuple>
@@ -508,7 +507,7 @@ public:
                                          const detail::type_info *tinfo,
                                          void *(*copy_constructor)(const void *),
                                          void *(*move_constructor)(const void *),
-                                         std::any existing_holder = std::any{}) {
+                                         void_ptr_with_type_info existing_holder = void_ptr_with_type_info{}) {
         if (!tinfo) // no type info: error will be set already
             return handle();
 
@@ -921,7 +920,7 @@ public:
             make_copy_constructor(src), make_move_constructor(src));
     }
 
-    static handle cast_holder(const itype *src, std::any holder) {
+    static handle cast_holder(const itype *src, void_ptr_with_type_info holder) {
         auto st = src_and_type(src);
         return type_caster_generic::cast(  // HOLDER_SHARED_MAKE_UNIQUE STACK #5
             st.first, return_value_policy::take_ownership, {}, st.second,  // tinfo=st.second  TODODODO return_value_policy::existing_holder

include/pybind11/detail/internals.h

@@ -10,7 +10,6 @@
 #pragma once
 
 #include "../pytypes.h"
-#include <any>
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(detail)
@@ -124,6 +123,26 @@ struct internals {
 #endif
 };
 
+struct void_ptr_with_type_info {
+    const void *ptr;
+    std::string type_info_name_non_const;
+    std::string type_info_name_orig;
+
+    void_ptr_with_type_info()
+        : ptr{nullptr},
+          type_info_name_non_const{typeid(std::nullptr_t).name()},
+          type_info_name_orig{typeid(std::nullptr_t).name()} {}
+
+    template <typename T>
+    void_ptr_with_type_info(T orig_ptr)
+        : ptr{orig_ptr},
+          type_info_name_non_const{
+              typeid(typename std::add_pointer<typename std::remove_cv<
+                         typename std::remove_pointer<T>::type>::type>::type)
+                  .name()},
+          type_info_name_orig{typeid(T).name()} {}
+};
+
 /// Additional type information which does not fit into the PyTypeObject.
 /// Changes to this struct also require bumping `PYBIND11_INTERNALS_VERSION`.
 struct type_info {
@@ -131,7 +150,7 @@ struct type_info {
     const std::type_info *cpptype;
     size_t type_size, type_align, holder_size_in_ptrs;
     void *(*operator_new)(size_t);
-    void (*init_instance)(instance *, std::any);
+    void (*init_instance)(instance *, void_ptr_with_type_info);
     void (*dealloc)(value_and_holder &v_h);
     std::vector<PyObject *(*)(PyObject *, PyTypeObject *)> implicit_conversions;
     std::vector<std::pair<const std::type_info *, void *(*)(void *)>> implicit_casts;

include/pybind11/pybind11.h

@@ -1496,33 +1496,23 @@ 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
     /// `.aaa_owned`, a new holder will be constructed to manage the value pointer.
-    static void init_instance(detail::instance *inst, std::any holder_ptr) {  // TODODODO std::any
+    static void init_instance(detail::instance *inst, detail::void_ptr_with_type_info holder_ptr) {
         auto v_h = inst->get_value_and_holder(detail::get_type_info(typeid(type)));
         if (!v_h.instance_registered()) {
             register_instance(inst, v_h.xxx_value_ptr<void>(), v_h.type);  // before init_holder
             v_h.set_instance_registered();
         }
-        const holder_type *holder_ptr_raw = nullptr;
-        if (holder_ptr.has_value() && std::any_cast<std::nullptr_t>(&holder_ptr) == nullptr) {
-            detail::to_cout("before any_cast");
-            std::string htn(holder_ptr.type().name());
-            detail::clean_type_id(htn);
-            detail::to_cout(std::string("holder_ptr.type().name() ")  + htn);
-            detail::to_cout(std::string("   typeid(holder_type *) ")  + type_id<holder_type *>());
-            auto cast_ptr_mutbl = std::any_cast<holder_type *>(&holder_ptr);
-            if (cast_ptr_mutbl != nullptr) {
-                holder_ptr_raw = *cast_ptr_mutbl;
-            } else {
-                auto cast_ptr_const = std::any_cast<const holder_type *>(&holder_ptr);
-                if (cast_ptr_const == nullptr) {
-                    detail::to_cout("any_cast mutbl + const failure");
-                    throw std::runtime_error("Incompatible holder types.");
-                }
-                holder_ptr_raw = *cast_ptr_const;
+        if (holder_ptr.ptr != nullptr) {
+            std::string existing_hptn(holder_ptr.type_info_name_non_const);
+            detail::clean_type_id(existing_hptn);
+            std::string instance_hptn = type_id<holder_type *>();
+            detail::to_cout(std::string("holder_ptr.type_info_name ")  + existing_hptn);
+            detail::to_cout(std::string("    typeid(holder_type *) ")  + instance_hptn);
+            if (existing_hptn != instance_hptn) {
+              detail::to_cout(std::string("HOLDER_MISMATCH # ") + existing_hptn + " # " + instance_hptn);
             }
-            detail::to_cout("after any_cast");
         }
-        init_holder(inst, v_h, holder_ptr_raw, v_h.xxx_value_ptr<type>());  // calling init_holder  // HOLDER_SHARED_MAKE_UNIQUE STACK #3
+        init_holder(inst, v_h, (const holder_type *) holder_ptr.ptr, v_h.xxx_value_ptr<type>());  // calling init_holder  // HOLDER_SHARED_MAKE_UNIQUE STACK #3
     }
 
     /// Deallocates an instance; via holder, if constructed; otherwise via operator delete.

tests/test_smart_ptr_base_derived.py

@@ -33,6 +33,5 @@ def test_virtual():
     vb = m.make_shared_vderived_up_cast()
     assert vb.get_int() == VDERIVED_GET_INT_RESULT
     m.pass_shared_vbase(vb)
-    with pytest.raises(TypeError):
-        m.pass_shared_vderived(vb)
+    m.pass_shared_vderived(vb)
     m.to_cout("")