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contrib/libcxxabi/src/private_typeinfo.cpp

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				//===----------------------- private_typeinfo.cpp -------------------------===//
				//
				// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
				// See https://llvm.org/LICENSE.txt for license information.
				// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
				//
				//===----------------------------------------------------------------------===//

				#include "private_typeinfo.h"

				// The flag _LIBCXX_DYNAMIC_FALLBACK is used to make dynamic_cast more
				// forgiving when type_info's mistakenly have hidden visibility and thus
				// multiple type_infos can exist for a single type.
				//
				// When _LIBCXX_DYNAMIC_FALLBACK is defined, and only in the case where
				// there is a detected inconsistency in the type_info hierarchy during a
				// dynamic_cast, then the equality operation will fall back to using strcmp
				// on type_info names to determine type_info equality.
				//
				// This change happens only under dynamic_cast, and only when
				// dynamic_cast is faced with the choice: abort, or possibly give back the
				// wrong answer. If when the dynamic_cast is done with this fallback
				// algorithm and an inconsistency is still detected, dynamic_cast will call
				// abort with an appropriate message.
				//
				// The current implementation of _LIBCXX_DYNAMIC_FALLBACK requires a
				// printf-like function called syslog:
				//
				// void syslog(int facility_priority, const char* format, ...);
				//
				// If you want this functionality but your platform doesn't have syslog,
				// just implement it in terms of fprintf(stderr, ...).
				//
				// _LIBCXX_DYNAMIC_FALLBACK is currently off by default.


				#include <string.h>


				#ifdef _LIBCXX_DYNAMIC_FALLBACK
				#include "abort_message.h"
				#include <sys/syslog.h>
				#endif

				// On Windows, typeids are different between DLLs and EXEs, so comparing
				// type_info* will work for typeids from the same compiled file but fail
				// for typeids from a DLL and an executable. Among other things, exceptions
				// are not caught by handlers since can_catch() returns false.
				//
				// Defining _LIBCXX_DYNAMIC_FALLBACK does not help since can_catch() calls
				// is_equal() with use_strcmp=false so the string names are not compared.

				#ifdef _WIN32
				#include <string.h>
				#endif

				static inline
				bool
				is_equal(const std::type_info* x, const std::type_info* y, bool use_strcmp)
				{
				#ifndef _WIN32
				if (!use_strcmp)
				return x == y;
				return strcmp(x->name(), y->name()) == 0;
				#else
				(void) use_strcmp;
				return (x == y) \|\| (strcmp(x->name(), y->name()) == 0);
				#endif
				}

				namespace __cxxabiv1
				{

				// __shim_type_info

				__shim_type_info::~__shim_type_info()
				{
				}

				void __shim_type_info::noop1() const {}
				void __shim_type_info::noop2() const {}

				// __fundamental_type_info

				// This miraculously (compiler magic) emits the type_info's for:
				// 1. all of the fundamental types
				// 2. pointers to all of the fundamental types
				// 3. pointers to all of the const fundamental types
				__fundamental_type_info::~__fundamental_type_info()
				{
				}

				// __array_type_info

				__array_type_info::~__array_type_info()
				{
				}

				// __function_type_info

				__function_type_info::~__function_type_info()
				{
				}

				// __enum_type_info

				__enum_type_info::~__enum_type_info()
				{
				}

				// __class_type_info

				__class_type_info::~__class_type_info()
				{
				}

				// __si_class_type_info

				__si_class_type_info::~__si_class_type_info()
				{
				}

				// __vmi_class_type_info

				__vmi_class_type_info::~__vmi_class_type_info()
				{
				}

				// __pbase_type_info

				__pbase_type_info::~__pbase_type_info()
				{
				}

				// __pointer_type_info

				__pointer_type_info::~__pointer_type_info()
				{
				}

				// __pointer_to_member_type_info

				__pointer_to_member_type_info::~__pointer_to_member_type_info()
				{
				}

				// can_catch

				// A handler is a match for an exception object of type E if
				// 1. The handler is of type cv T or cv T& and E and T are the same type
				// (ignoring the top-level cv-qualifiers), or
				// 2. the handler is of type cv T or cv T& and T is an unambiguous public
				// base class of E, or
				// 3. the handler is of type cv1 T* cv2 and E is a pointer type that can be
				// converted to the type of the handler by either or both of
				// A. a standard pointer conversion (4.10) not involving conversions to
				// pointers to private or protected or ambiguous classes
				// B. a qualification conversion
				// 4. the handler is a pointer or pointer to member type and E is
				// std::nullptr_t.

				// adjustedPtr:
				//
				// catch (A& a) : adjustedPtr == &a
				// catch (A* a) : adjustedPtr == a
				// catch (A** a) : adjustedPtr == a
				//
				// catch (D2& d2) : adjustedPtr == &d2 (d2 is base class of thrown object)
				// catch (D2* d2) : adjustedPtr == d2
				// catch (D2*& d2) : adjustedPtr == d2
				//
				// catch (...) : adjustedPtr == & of the exception
				//
				// If the thrown type is nullptr_t and the caught type is a pointer to
				// member type, adjustedPtr points to a statically-allocated null pointer
				// representation of that type.

				// Handles bullet 1
				bool
				__fundamental_type_info::can_catch(const __shim_type_info* thrown_type,
				void*&) const
				{
				return is_equal(this, thrown_type, false);
				}

				bool
				__array_type_info::can_catch(const __shim_type_info, void&) const
				{
				// We can get here if someone tries to catch an array by reference.
				// However if someone tries to throw an array, it immediately gets
				// converted to a pointer, which will not convert back to an array
				// at the catch clause. So this can never catch anything.
				return false;
				}

				bool
				__function_type_info::can_catch(const __shim_type_info, void&) const
				{
				// We can get here if someone tries to catch a function by reference.
				// However if someone tries to throw a function, it immediately gets
				// converted to a pointer, which will not convert back to a function
				// at the catch clause. So this can never catch anything.
				return false;
				}

				// Handles bullet 1
				bool
				__enum_type_info::can_catch(const __shim_type_info* thrown_type,
				void*&) const
				{
				return is_equal(this, thrown_type, false);
				}

				#ifdef __clang__
				#pragma clang diagnostic push
				#pragma clang diagnostic ignored "-Wmissing-field-initializers"
				#endif

				// Handles bullets 1 and 2
				bool
				__class_type_info::can_catch(const __shim_type_info* thrown_type,
				void*& adjustedPtr) const
				{
				// bullet 1
				if (is_equal(this, thrown_type, false))
				return true;
				const __class_type_info* thrown_class_type =
				dynamic_cast<const __class_type_info*>(thrown_type);
				if (thrown_class_type == 0)
				return false;
				// bullet 2
				__dynamic_cast_info info = {thrown_class_type, 0, this, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,};
				info.number_of_dst_type = 1;
				thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
				if (info.path_dst_ptr_to_static_ptr == public_path)
				{
				adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
				return true;
				}
				return false;
				}

				#ifdef __clang__
				#pragma clang diagnostic pop
				#endif

				void
				__class_type_info::process_found_base_class(__dynamic_cast_info* info,
				void* adjustedPtr,
				int path_below) const
				{
				if (info->dst_ptr_leading_to_static_ptr == 0)
				{
				// First time here
				info->dst_ptr_leading_to_static_ptr = adjustedPtr;
				info->path_dst_ptr_to_static_ptr = path_below;
				info->number_to_static_ptr = 1;
				}
				else if (info->dst_ptr_leading_to_static_ptr == adjustedPtr)
				{
				// We've been here before. Update path to "most public"
				if (info->path_dst_ptr_to_static_ptr == not_public_path)
				info->path_dst_ptr_to_static_ptr = path_below;
				}
				else
				{
				// We've detected an ambiguous cast from (thrown_class_type, adjustedPtr)
				// to a static_type
				info->number_to_static_ptr += 1;
				info->path_dst_ptr_to_static_ptr = not_public_path;
				info->search_done = true;
				}
				}

				void
				__class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
				void* adjustedPtr,
				int path_below) const
				{
				if (is_equal(this, info->static_type, false))
				process_found_base_class(info, adjustedPtr, path_below);
				}

				void
				__si_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
				void* adjustedPtr,
				int path_below) const
				{
				if (is_equal(this, info->static_type, false))
				process_found_base_class(info, adjustedPtr, path_below);
				else
				__base_type->has_unambiguous_public_base(info, adjustedPtr, path_below);
				}

				void
				__base_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
				void* adjustedPtr,
				int path_below) const
				{
				ptrdiff_t offset_to_base = 0;
				if (adjustedPtr != nullptr)
				{
				offset_to_base = __offset_flags >> __offset_shift;
				if (__offset_flags & __virtual_mask)
				{
				const char* vtable = static_cast<const charconst*>(adjustedPtr);
				offset_to_base = reinterpret_cast<const ptrdiff_t>(vtable + offset_to_base);
				}
				}
				__base_type->has_unambiguous_public_base(
				info,
				static_cast<char*>(adjustedPtr) + offset_to_base,
				(__offset_flags & __public_mask) ? path_below : not_public_path);
				}

				void
				__vmi_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
				void* adjustedPtr,
				int path_below) const
				{
				if (is_equal(this, info->static_type, false))
				process_found_base_class(info, adjustedPtr, path_below);
				else
				{
				typedef const __base_class_type_info* Iter;
				const Iter e = __base_info + __base_count;
				Iter p = __base_info;
				p->has_unambiguous_public_base(info, adjustedPtr, path_below);
				if (++p < e)
				{
				do
				{
				p->has_unambiguous_public_base(info, adjustedPtr, path_below);
				if (info->search_done)
				break;
				} while (++p < e);
				}
				}
				}

				// Handles bullet 1 for both pointers and member pointers
				bool
				__pbase_type_info::can_catch(const __shim_type_info* thrown_type,
				void*&) const
				{
				bool use_strcmp = this->__flags & (__incomplete_class_mask \|
				__incomplete_mask);
				if (!use_strcmp) {
				const __pbase_type_info* thrown_pbase = dynamic_cast<const __pbase_type_info*>(
				thrown_type);
				if (!thrown_pbase) return false;
				use_strcmp = thrown_pbase->__flags & (__incomplete_class_mask \|
				__incomplete_mask);
				}
				return is_equal(this, thrown_type, use_strcmp);
				}

				#ifdef __clang__
				#pragma clang diagnostic push
				#pragma clang diagnostic ignored "-Wmissing-field-initializers"
				#endif

				// Handles bullets 1, 3 and 4
				// NOTE: It might not be safe to adjust the pointer if it is not not a pointer
				// type. Only adjust the pointer after we know it is safe to do so.
				bool
				__pointer_type_info::can_catch(const __shim_type_info* thrown_type,
				void*& adjustedPtr) const
				{
				// bullet 4
				if (is_equal(thrown_type, &typeid(std::nullptr_t), false)) {
				adjustedPtr = nullptr;
				return true;
				}

				// bullet 1
				if (__pbase_type_info::can_catch(thrown_type, adjustedPtr)) {
				if (adjustedPtr != NULL)
				adjustedPtr = static_cast<void*>(adjustedPtr);
				return true;
				}
				// bullet 3
				const __pointer_type_info* thrown_pointer_type =
				dynamic_cast<const __pointer_type_info*>(thrown_type);
				if (thrown_pointer_type == 0)
				return false;
				// Do the dereference adjustment
				if (adjustedPtr != NULL)
				adjustedPtr = static_cast<void*>(adjustedPtr);
				// bullet 3B and 3C
				if (thrown_pointer_type->__flags & ~__flags & __no_remove_flags_mask)
				return false;
				if (__flags & ~thrown_pointer_type->__flags & __no_add_flags_mask)
				return false;
				if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
				return true;
				// bullet 3A
				if (is_equal(__pointee, &typeid(void), false)) {
				// pointers to functions cannot be converted to void*.
				// pointers to member functions are not handled here.
				const __function_type_info* thrown_function =
				dynamic_cast<const __function_type_info*>(thrown_pointer_type->__pointee);
				return (thrown_function == nullptr);
				}
				// Handle pointer to pointer
				const __pointer_type_info* nested_pointer_type =
				dynamic_cast<const __pointer_type_info*>(__pointee);
				if (nested_pointer_type) {
				if (~__flags & __const_mask) return false;
				return nested_pointer_type->can_catch_nested(thrown_pointer_type->__pointee);
				}

				// Handle pointer to pointer to member
				const __pointer_to_member_type_info* member_ptr_type =
				dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
				if (member_ptr_type) {
				if (~__flags & __const_mask) return false;
				return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
				}

				// Handle pointer to class type
				const __class_type_info* catch_class_type =
				dynamic_cast<const __class_type_info*>(__pointee);
				if (catch_class_type == 0)
				return false;
				const __class_type_info* thrown_class_type =
				dynamic_cast<const __class_type_info*>(thrown_pointer_type->__pointee);
				if (thrown_class_type == 0)
				return false;
				__dynamic_cast_info info = {thrown_class_type, 0, catch_class_type, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,};
				info.number_of_dst_type = 1;
				thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
				if (info.path_dst_ptr_to_static_ptr == public_path)
				{
				if (adjustedPtr != NULL)
				adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
				return true;
				}
				return false;
				}

				bool __pointer_type_info::can_catch_nested(
				const __shim_type_info* thrown_type) const
				{
				const __pointer_type_info* thrown_pointer_type =
				dynamic_cast<const __pointer_type_info*>(thrown_type);
				if (thrown_pointer_type == 0)
				return false;
				// bullet 3B
				if (thrown_pointer_type->__flags & ~__flags)
				return false;
				if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
				return true;
				// If the pointed to types differ then the catch type must be const
				// qualified.
				if (~__flags & __const_mask)
				return false;

				// Handle pointer to pointer
				const __pointer_type_info* nested_pointer_type =
				dynamic_cast<const __pointer_type_info*>(__pointee);
				if (nested_pointer_type) {
				return nested_pointer_type->can_catch_nested(
				thrown_pointer_type->__pointee);
				}

				// Handle pointer to pointer to member
				const __pointer_to_member_type_info* member_ptr_type =
				dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
				if (member_ptr_type) {
				return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
				}

				return false;
				}

				bool __pointer_to_member_type_info::can_catch(
				const __shim_type_info* thrown_type, void*& adjustedPtr) const {
				// bullet 4
				if (is_equal(thrown_type, &typeid(std::nullptr_t), false)) {
				// We assume that the pointer to member representation is the same for
				// all pointers to data members and for all pointers to member functions.
				struct X {};
				if (dynamic_cast<const __function_type_info*>(__pointee)) {
				static int (X::*const null_ptr_rep)() = nullptr;
				adjustedPtr = const_cast<int (X::**)()>(&null_ptr_rep);
				} else {
				static int X::*const null_ptr_rep = nullptr;
				adjustedPtr = const_cast<int X::**>(&null_ptr_rep);
				}
				return true;
				}

				// bullet 1
				if (__pbase_type_info::can_catch(thrown_type, adjustedPtr))
				return true;

				const __pointer_to_member_type_info* thrown_pointer_type =
				dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
				if (thrown_pointer_type == 0)
				return false;
				if (thrown_pointer_type->__flags & ~__flags & __no_remove_flags_mask)
				return false;
				if (__flags & ~thrown_pointer_type->__flags & __no_add_flags_mask)
				return false;
				if (!is_equal(__pointee, thrown_pointer_type->__pointee, false))
				return false;
				if (is_equal(__context, thrown_pointer_type->__context, false))
				return true;

				// [except.handle] does not allow the pointer-to-member conversions mentioned
				// in [mem.conv] to take place. For this reason we don't check Derived->Base
				// for Derived->Base conversions.

				return false;
				}

				bool __pointer_to_member_type_info::can_catch_nested(
				const __shim_type_info* thrown_type) const
				{
				const __pointer_to_member_type_info* thrown_member_ptr_type =
				dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
				if (thrown_member_ptr_type == 0)
				return false;
				if (~__flags & thrown_member_ptr_type->__flags)
				return false;
				if (!is_equal(__pointee, thrown_member_ptr_type->__pointee, false))
				return false;
				if (!is_equal(__context, thrown_member_ptr_type->__context, false))
				return false;
				return true;
				}

				#ifdef __clang__
				#pragma clang diagnostic pop
				#endif

				#ifdef __clang__
				#pragma clang diagnostic push
				#pragma clang diagnostic ignored "-Wmissing-field-initializers"
				#endif

				// __dynamic_cast

				// static_ptr: pointer to an object of type static_type; nonnull, and since the
				// object is polymorphic, (void*)static_ptr is a virtual table pointer.
				// static_ptr is &v in the expression dynamic_cast<T>(v).
				// static_type: static type of the object pointed to by static_ptr.
				// dst_type: destination type of the cast (the "T" in "dynamic_cast<T>(v)").
				// src2dst_offset: a static hint about the location of the
				// source subobject with respect to the complete object;
				// special negative values are:
				// -1: no hint
				// -2: static_type is not a public base of dst_type
				// -3: static_type is a multiple public base type but never a
				// virtual base type
				// otherwise, the static_type type is a unique public nonvirtual
				// base type of dst_type at offset src2dst_offset from the
				// origin of dst_type.
				//
				// (dynamic_ptr, dynamic_type) are the run time type of the complete object
				// referred to by static_ptr and a pointer to it. These can be found from
				// static_ptr for polymorphic types.
				// static_type is guaranteed to be a polymorphic type.
				//
				// (dynamic_ptr, dynamic_type) is the root of a DAG that grows upward. Each
				// node of the tree represents a base class/object of its parent (or parents) below.
				// Each node is uniquely represented by a pointer to the object, and a pointer
				// to a type_info - its type. Different nodes may have the same pointer and
				// different nodes may have the same type. But only one node has a specific
				// (pointer-value, type) pair. In C++ two objects of the same type can not
				// share the same address.
				//
				// There are two flavors of nodes which have the type dst_type:
				// 1. Those that are derived from (below) (static_ptr, static_type).
				// 2. Those that are not derived from (below) (static_ptr, static_type).
				//
				// Invariants of the DAG:
				//
				// There is at least one path from the root (dynamic_ptr, dynamic_type) to
				// the node (static_ptr, static_type). This path may or may not be public.
				// There may be more than one such path (some public some not). Such a path may
				// or may not go through a node having type dst_type.
				//
				// No node of type T appears above a node of the same type. That means that
				// there is only one node with dynamic_type. And if dynamic_type == dst_type,
				// then there is only one dst_type in the DAG.
				//
				// No node of type dst_type appears above a node of type static_type. Such
				// DAG's are possible in C++, but the compiler computes those dynamic_casts at
				// compile time, and only calls __dynamic_cast when dst_type lies below
				// static_type in the DAG.
				//
				// dst_type != static_type: The compiler computes the dynamic_cast in this case too.
				// dynamic_type != static_type: The compiler computes the dynamic_cast in this case too.
				//
				// Returns:
				//
				// If there is exactly one dst_type of flavor 1, and
				// If there is a public path from that dst_type to (static_ptr, static_type), or
				// If there are 0 dst_types of flavor 2, and there is a public path from
				// (dynamic_ptr, dynamic_type) to (static_ptr, static_type) and a public
				// path from (dynamic_ptr, dynamic_type) to the one dst_type, then return
				// a pointer to that dst_type.
				// Else if there are 0 dst_types of flavor 1 and exactly 1 dst_type of flavor 2, and
				// if there is a public path from (dynamic_ptr, dynamic_type) to
				// (static_ptr, static_type) and a public path from (dynamic_ptr, dynamic_type)
				// to the one dst_type, then return a pointer to that one dst_type.
				// Else return nullptr.
				//
				// If dynamic_type == dst_type, then the above algorithm collapses to the
				// following cheaper algorithm:
				//
				// If there is a public path from (dynamic_ptr, dynamic_type) to
				// (static_ptr, static_type), then return dynamic_ptr.
				// Else return nullptr.

				extern "C" _LIBCXXABI_FUNC_VIS void *
				__dynamic_cast(const void static_ptr, const __class_type_info static_type,
				const __class_type_info *dst_type,
				std::ptrdiff_t src2dst_offset) {
				// Possible future optimization: Take advantage of src2dst_offset
				// Currently clang always sets src2dst_offset to -1 (no hint).

				// Get (dynamic_ptr, dynamic_type) from static_ptr
				void *vtable = static_cast<void ** const *>(static_ptr);
				ptrdiff_t offset_to_derived = reinterpret_cast<ptrdiff_t>(vtable[-2]);
				const void* dynamic_ptr = static_cast<const char*>(static_ptr) + offset_to_derived;
				const __class_type_info* dynamic_type = static_cast<const __class_type_info*>(vtable[-1]);

				// Initialize answer to nullptr. This will be changed from the search
				// results if a non-null answer is found. Regardless, this is what will
				// be returned.
				const void* dst_ptr = 0;
				// Initialize info struct for this search.
				__dynamic_cast_info info = {dst_type, static_ptr, static_type, src2dst_offset, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,};

				// Find out if we can use a giant short cut in the search
				if (is_equal(dynamic_type, dst_type, false))
				{
				// Using giant short cut. Add that information to info.
				info.number_of_dst_type = 1;
				// Do the search
				dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, false);
				#ifdef _LIBCXX_DYNAMIC_FALLBACK
				// The following if should always be false because we should definitely
				// find (static_ptr, static_type), either on a public or private path
				if (info.path_dst_ptr_to_static_ptr == unknown)
				{
				// We get here only if there is some kind of visibility problem
				// in client code.
				syslog(LOG_ERR, "dynamic_cast error 1: Both of the following type_info's "
				"should have public visibility. At least one of them is hidden. %s"
				", %s.\n", static_type->name(), dynamic_type->name());
				// Redo the search comparing type_info's using strcmp
				info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
				info.number_of_dst_type = 1;
				dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, true);
				}
				#endif // _LIBCXX_DYNAMIC_FALLBACK
				// Query the search.
				if (info.path_dst_ptr_to_static_ptr == public_path)
				dst_ptr = dynamic_ptr;
				}
				else
				{
				// Not using giant short cut. Do the search
				dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, false);
				#ifdef _LIBCXX_DYNAMIC_FALLBACK
				// The following if should always be false because we should definitely
				// find (static_ptr, static_type), either on a public or private path
				if (info.path_dst_ptr_to_static_ptr == unknown &&
				info.path_dynamic_ptr_to_static_ptr == unknown)
				{
				syslog(LOG_ERR, "dynamic_cast error 2: One or more of the following type_info's "
				"has hidden visibility or is defined in more than one translation "
				"unit. They should all have public visibility. "
				"%s, %s, %s.\n", static_type->name(), dynamic_type->name(),
				dst_type->name());
				// Redo the search comparing type_info's using strcmp
				info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
				dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, true);
				}
				#endif // _LIBCXX_DYNAMIC_FALLBACK
				// Query the search.
				switch (info.number_to_static_ptr)
				{
				case 0:
				if (info.number_to_dst_ptr == 1 &&
				info.path_dynamic_ptr_to_static_ptr == public_path &&
				info.path_dynamic_ptr_to_dst_ptr == public_path)
				dst_ptr = info.dst_ptr_not_leading_to_static_ptr;
				break;
				case 1:
				if (info.path_dst_ptr_to_static_ptr == public_path \|\|
				(
				info.number_to_dst_ptr == 0 &&
				info.path_dynamic_ptr_to_static_ptr == public_path &&
				info.path_dynamic_ptr_to_dst_ptr == public_path
				)
				)
				dst_ptr = info.dst_ptr_leading_to_static_ptr;
				break;
				}
				}
				return const_cast<void*>(dst_ptr);
				}

				#ifdef __clang__
				#pragma clang diagnostic pop
				#endif

				// Call this function when you hit a static_type which is a base (above) a dst_type.
				// Let caller know you hit a static_type. But only start recording details if
				// this is (static_ptr, static_type) -- the node we are casting from.
				// If this is (static_ptr, static_type)
				// Record the path (public or not) from the dst_type to here. There may be
				// multiple paths from the same dst_type to here, record the "most public" one.
				// Record the dst_ptr as pointing to (static_ptr, static_type).
				// If more than one (dst_ptr, dst_type) points to (static_ptr, static_type),
				// then mark this dyanmic_cast as ambiguous and stop the search.
				void
				__class_type_info::process_static_type_above_dst(__dynamic_cast_info* info,
				const void* dst_ptr,
				const void* current_ptr,
				int path_below) const
				{
				// Record that we found a static_type
				info->found_any_static_type = true;
				if (current_ptr == info->static_ptr)
				{
				// Record that we found (static_ptr, static_type)
				info->found_our_static_ptr = true;
				if (info->dst_ptr_leading_to_static_ptr == 0)
				{
				// First time here
				info->dst_ptr_leading_to_static_ptr = dst_ptr;
				info->path_dst_ptr_to_static_ptr = path_below;
				info->number_to_static_ptr = 1;
				// If there is only one dst_type in the entire tree and the path from
				// there to here is public then we are done!
				if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
				info->search_done = true;
				}
				else if (info->dst_ptr_leading_to_static_ptr == dst_ptr)
				{
				// We've been here before. Update path to "most public"
				if (info->path_dst_ptr_to_static_ptr == not_public_path)
				info->path_dst_ptr_to_static_ptr = path_below;
				// If there is only one dst_type in the entire tree and the path from
				// there to here is public then we are done!
				if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
				info->search_done = true;
				}
				else
				{
				// We've detected an ambiguous cast from (static_ptr, static_type)
				// to a dst_type
				info->number_to_static_ptr += 1;
				info->search_done = true;
				}
				}
				}

				// Call this function when you hit a static_type which is not a base (above) a dst_type.
				// If this is (static_ptr, static_type)
				// Record the path (public or not) from (dynamic_ptr, dynamic_type) to here. There may be
				// multiple paths from (dynamic_ptr, dynamic_type) to here, record the "most public" one.
				void
				__class_type_info::process_static_type_below_dst(__dynamic_cast_info* info,
				const void* current_ptr,
				int path_below) const
				{
				if (current_ptr == info->static_ptr)
				{
				// Record the most public path from (dynamic_ptr, dynamic_type) to
				// (static_ptr, static_type)
				if (info->path_dynamic_ptr_to_static_ptr != public_path)
				info->path_dynamic_ptr_to_static_ptr = path_below;
				}
				}

				// Call this function when searching below a dst_type node. This function searches
				// for a path to (static_ptr, static_type) and for paths to one or more dst_type nodes.
				// If it finds a static_type node, there is no need to further search base classes
				// above.
				// If it finds a dst_type node it should search base classes using search_above_dst
				// to find out if this dst_type points to (static_ptr, static_type) or not.
				// Either way, the dst_type is recorded as one of two "flavors": one that does
				// or does not point to (static_ptr, static_type).
				// If this is neither a static_type nor a dst_type node, continue searching
				// base classes above.
				// All the hoopla surrounding the search code is doing nothing but looking for
				// excuses to stop the search prematurely (break out of the for-loop). That is,
				// the algorithm below is simply an optimization of this:
				// void
				// __vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
				// const void* current_ptr,
				// int path_below) const
				// {
				// typedef const __base_class_type_info* Iter;
				// if (this == info->static_type)
				// process_static_type_below_dst(info, current_ptr, path_below);
				// else if (this == info->dst_type)
				// {
				// // Record the most public access path that got us here
				// if (info->path_dynamic_ptr_to_dst_ptr != public_path)
				// info->path_dynamic_ptr_to_dst_ptr = path_below;
				// bool does_dst_type_point_to_our_static_type = false;
				// for (Iter p = __base_info, e= __base_info + __base_count; p < e; ++p)
				// {
				// p->search_above_dst(info, current_ptr, current_ptr, public_path);
				// if (info->found_our_static_ptr)
				// does_dst_type_point_to_our_static_type = true;
				// // break out early here if you can detect it doesn't matter if you do
				// }
				// if (!does_dst_type_point_to_our_static_type)
				// {
				// // We found a dst_type that doesn't point to (static_ptr, static_type)
				// // So record the address of this dst_ptr and increment the
				// // count of the number of such dst_types found in the tree.
				// info->dst_ptr_not_leading_to_static_ptr = current_ptr;
				// info->number_to_dst_ptr += 1;
				// }
				// }
				// else
				// {
				// // This is not a static_type and not a dst_type.
				// for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
				// {
				// p->search_below_dst(info, current_ptr, public_path);
				// // break out early here if you can detect it doesn't matter if you do
				// }
				// }
				// }
				void
				__vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				typedef const __base_class_type_info* Iter;
				if (is_equal(this, info->static_type, use_strcmp))
				process_static_type_below_dst(info, current_ptr, path_below);
				else if (is_equal(this, info->dst_type, use_strcmp))
				{
				// We've been here before if we've recorded current_ptr in one of these
				// two places:
				if (current_ptr == info->dst_ptr_leading_to_static_ptr \|\|
				current_ptr == info->dst_ptr_not_leading_to_static_ptr)
				{
				// We've seen this node before, and therefore have already searched
				// its base classes above.
				// Update path to here that is "most public".
				if (path_below == public_path)
				info->path_dynamic_ptr_to_dst_ptr = public_path;
				}
				else // We have haven't been here before
				{
				// Record the access path that got us here
				// If there is more than one dst_type this path doesn't matter.
				info->path_dynamic_ptr_to_dst_ptr = path_below;
				bool does_dst_type_point_to_our_static_type = false;
				// Only search above here if dst_type derives from static_type, or
				// if it is unknown if dst_type derives from static_type.
				if (info->is_dst_type_derived_from_static_type != no)
				{
				// Set up flags to record results from all base classes
				bool is_dst_type_derived_from_static_type = false;

				// We've found a dst_type with a potentially public path to here.
				// We have to assume the path is public because it may become
				// public later (if we get back to here with a public path).
				// We can stop looking above if:
				// 1. We've found a public path to (static_ptr, static_type).
				// 2. We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
				// This is detected at the (static_ptr, static_type).
				// 3. We can prove that there is no public path to (static_ptr, static_type)
				// above here.
				const Iter e = __base_info + __base_count;
				for (Iter p = __base_info; p < e; ++p)
				{
				// Zero out found flags
				info->found_our_static_ptr = false;
				info->found_any_static_type = false;
				p->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
				if (info->search_done)
				break;
				if (info->found_any_static_type)
				{
				is_dst_type_derived_from_static_type = true;
				if (info->found_our_static_ptr)
				{
				does_dst_type_point_to_our_static_type = true;
				// If we found what we're looking for, stop looking above.
				if (info->path_dst_ptr_to_static_ptr == public_path)
				break;
				// We found a private path to (static_ptr, static_type)
				// If there is no diamond then there is only one path
				// to (static_ptr, static_type) and we just found it.
				if (!(__flags & __diamond_shaped_mask))
				break;
				}
				else
				{
				// If we found a static_type that isn't the one we're looking
				// for, and if there are no repeated types above here,
				// then stop looking.
				if (!(__flags & __non_diamond_repeat_mask))
				break;
				}
				}
				}
				// If we found no static_type,s then dst_type doesn't derive
				// from static_type, else it does. Record this result so that
				// next time we hit a dst_type we will know not to search above
				// it if it doesn't derive from static_type.
				if (is_dst_type_derived_from_static_type)
				info->is_dst_type_derived_from_static_type = yes;
				else
				info->is_dst_type_derived_from_static_type = no;
				}
				if (!does_dst_type_point_to_our_static_type)
				{
				// We found a dst_type that doesn't point to (static_ptr, static_type)
				// So record the address of this dst_ptr and increment the
				// count of the number of such dst_types found in the tree.
				info->dst_ptr_not_leading_to_static_ptr = current_ptr;
				info->number_to_dst_ptr += 1;
				// If there exists another dst with a private path to
				// (static_ptr, static_type), then the cast from
				// (dynamic_ptr, dynamic_type) to dst_type is now ambiguous,
				// so stop search.
				if (info->number_to_static_ptr == 1 &&
				info->path_dst_ptr_to_static_ptr == not_public_path)
				info->search_done = true;
				}
				}
				}
				else
				{
				// This is not a static_type and not a dst_type.
				const Iter e = __base_info + __base_count;
				Iter p = __base_info;
				p->search_below_dst(info, current_ptr, path_below, use_strcmp);
				if (++p < e)
				{
				if ((__flags & __diamond_shaped_mask) \|\| info->number_to_static_ptr == 1)
				{
				// If there are multiple paths to a base above from here, or if
				// a dst_type pointing to (static_ptr, static_type) has been found,
				// then there is no way to break out of this loop early unless
				// something below detects the search is done.
				do
				{
				if (info->search_done)
				break;
				p->search_below_dst(info, current_ptr, path_below, use_strcmp);
				} while (++p < e);
				}
				else if (__flags & __non_diamond_repeat_mask)
				{
				// There are not multiple paths to any base class from here and a
				// dst_type pointing to (static_ptr, static_type) has not yet been
				// found.
				do
				{
				if (info->search_done)
				break;
				// If we just found a dst_type with a public path to (static_ptr, static_type),
				// then the only reason to continue the search is to make sure
				// no other dst_type points to (static_ptr, static_type).
				// If !diamond, then we don't need to search here.
				if (info->number_to_static_ptr == 1 &&
				info->path_dst_ptr_to_static_ptr == public_path)
				break;
				p->search_below_dst(info, current_ptr, path_below, use_strcmp);
				} while (++p < e);
				}
				else
				{
				// There are no repeated types above this node.
				// There are no nodes with multiple parents above this node.
				// no dst_type has been found to (static_ptr, static_type)
				do
				{
				if (info->search_done)
				break;
				// If we just found a dst_type with a public path to (static_ptr, static_type),
				// then the only reason to continue the search is to make sure sure
				// no other dst_type points to (static_ptr, static_type).
				// If !diamond, then we don't need to search here.
				// if we just found a dst_type with a private path to (static_ptr, static_type),
				// then we're only looking for a public path to (static_ptr, static_type)
				// and to check for other dst_types.
				// If !diamond & !repeat, then there is not a pointer to (static_ptr, static_type)
				// and not a dst_type under here.
				if (info->number_to_static_ptr == 1)
				break;
				p->search_below_dst(info, current_ptr, path_below, use_strcmp);
				} while (++p < e);
				}
				}
				}
				}

				// This is the same algorithm as __vmi_class_type_info::search_below_dst but
				// simplified to the case that there is only a single base class.
				void
				__si_class_type_info::search_below_dst(__dynamic_cast_info* info,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				if (is_equal(this, info->static_type, use_strcmp))
				process_static_type_below_dst(info, current_ptr, path_below);
				else if (is_equal(this, info->dst_type, use_strcmp))
				{
				// We've been here before if we've recorded current_ptr in one of these
				// two places:
				if (current_ptr == info->dst_ptr_leading_to_static_ptr \|\|
				current_ptr == info->dst_ptr_not_leading_to_static_ptr)
				{
				// We've seen this node before, and therefore have already searched
				// its base classes above.
				// Update path to here that is "most public".
				if (path_below == public_path)
				info->path_dynamic_ptr_to_dst_ptr = public_path;
				}
				else // We have haven't been here before
				{
				// Record the access path that got us here
				// If there is more than one dst_type this path doesn't matter.
				info->path_dynamic_ptr_to_dst_ptr = path_below;
				bool does_dst_type_point_to_our_static_type = false;
				// Only search above here if dst_type derives from static_type, or
				// if it is unknown if dst_type derives from static_type.
				if (info->is_dst_type_derived_from_static_type != no)
				{
				// Set up flags to record results from all base classes
				bool is_dst_type_derived_from_static_type = false;
				// Zero out found flags
				info->found_our_static_ptr = false;
				info->found_any_static_type = false;
				__base_type->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
				if (info->found_any_static_type)
				{
				is_dst_type_derived_from_static_type = true;
				if (info->found_our_static_ptr)
				does_dst_type_point_to_our_static_type = true;
				}
				// If we found no static_type,s then dst_type doesn't derive
				// from static_type, else it does. Record this result so that
				// next time we hit a dst_type we will know not to search above
				// it if it doesn't derive from static_type.
				if (is_dst_type_derived_from_static_type)
				info->is_dst_type_derived_from_static_type = yes;
				else
				info->is_dst_type_derived_from_static_type = no;
				}
				if (!does_dst_type_point_to_our_static_type)
				{
				// We found a dst_type that doesn't point to (static_ptr, static_type)
				// So record the address of this dst_ptr and increment the
				// count of the number of such dst_types found in the tree.
				info->dst_ptr_not_leading_to_static_ptr = current_ptr;
				info->number_to_dst_ptr += 1;
				// If there exists another dst with a private path to
				// (static_ptr, static_type), then the cast from
				// (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
				if (info->number_to_static_ptr == 1 &&
				info->path_dst_ptr_to_static_ptr == not_public_path)
				info->search_done = true;
				}
				}
				}
				else
				{
				// This is not a static_type and not a dst_type
				__base_type->search_below_dst(info, current_ptr, path_below, use_strcmp);
				}
				}

				// This is the same algorithm as __vmi_class_type_info::search_below_dst but
				// simplified to the case that there is no base class.
				void
				__class_type_info::search_below_dst(__dynamic_cast_info* info,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				if (is_equal(this, info->static_type, use_strcmp))
				process_static_type_below_dst(info, current_ptr, path_below);
				else if (is_equal(this, info->dst_type, use_strcmp))
				{
				// We've been here before if we've recorded current_ptr in one of these
				// two places:
				if (current_ptr == info->dst_ptr_leading_to_static_ptr \|\|
				current_ptr == info->dst_ptr_not_leading_to_static_ptr)
				{
				// We've seen this node before, and therefore have already searched
				// its base classes above.
				// Update path to here that is "most public".
				if (path_below == public_path)
				info->path_dynamic_ptr_to_dst_ptr = public_path;
				}
				else // We have haven't been here before
				{
				// Record the access path that got us here
				// If there is more than one dst_type this path doesn't matter.
				info->path_dynamic_ptr_to_dst_ptr = path_below;
				// We found a dst_type that doesn't point to (static_ptr, static_type)
				// So record the address of this dst_ptr and increment the
				// count of the number of such dst_types found in the tree.
				info->dst_ptr_not_leading_to_static_ptr = current_ptr;
				info->number_to_dst_ptr += 1;
				// If there exists another dst with a private path to
				// (static_ptr, static_type), then the cast from
				// (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
				if (info->number_to_static_ptr == 1 &&
				info->path_dst_ptr_to_static_ptr == not_public_path)
				info->search_done = true;
				// We found that dst_type does not derive from static_type
				info->is_dst_type_derived_from_static_type = no;
				}
				}
				}

				// Call this function when searching above a dst_type node. This function searches
				// for a public path to (static_ptr, static_type).
				// This function is guaranteed not to find a node of type dst_type.
				// Theoretically this is a very simple function which just stops if it finds a
				// static_type node: All the hoopla surrounding the search code is doing
				// nothing but looking for excuses to stop the search prematurely (break out of
				// the for-loop). That is, the algorithm below is simply an optimization of this:
				// void
				// __vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
				// const void* dst_ptr,
				// const void* current_ptr,
				// int path_below) const
				// {
				// if (this == info->static_type)
				// process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
				// else
				// {
				// typedef const __base_class_type_info* Iter;
				// // This is not a static_type and not a dst_type
				// for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
				// {
				// p->search_above_dst(info, dst_ptr, current_ptr, public_path);
				// // break out early here if you can detect it doesn't matter if you do
				// }
				// }
				// }
				void
				__vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
				const void* dst_ptr,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				if (is_equal(this, info->static_type, use_strcmp))
				process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
				else
				{
				typedef const __base_class_type_info* Iter;
				// This is not a static_type and not a dst_type
				// Save flags so they can be restored when returning to nodes below.
				bool found_our_static_ptr = info->found_our_static_ptr;
				bool found_any_static_type = info->found_any_static_type;
				// We've found a dst_type below with a path to here. If the path
				// to here is not public, there may be another path to here that
				// is public. So we have to assume that the path to here is public.
				// We can stop looking above if:
				// 1. We've found a public path to (static_ptr, static_type).
				// 2. We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
				// This is detected at the (static_ptr, static_type).
				// 3. We can prove that there is no public path to (static_ptr, static_type)
				// above here.
				const Iter e = __base_info + __base_count;
				Iter p = __base_info;
				// Zero out found flags
				info->found_our_static_ptr = false;
				info->found_any_static_type = false;
				p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
				found_our_static_ptr \|= info->found_our_static_ptr;
				found_any_static_type \|= info->found_any_static_type;
				if (++p < e)
				{
				do
				{
				if (info->search_done)
				break;
				if (info->found_our_static_ptr)
				{
				// If we found what we're looking for, stop looking above.
				if (info->path_dst_ptr_to_static_ptr == public_path)
				break;
				// We found a private path to (static_ptr, static_type)
				// If there is no diamond then there is only one path
				// to (static_ptr, static_type) from here and we just found it.
				if (!(__flags & __diamond_shaped_mask))
				break;
				}
				else if (info->found_any_static_type)
				{
				// If we found a static_type that isn't the one we're looking
				// for, and if there are no repeated types above here,
				// then stop looking.
				if (!(__flags & __non_diamond_repeat_mask))
				break;
				}
				// Zero out found flags
				info->found_our_static_ptr = false;
				info->found_any_static_type = false;
				p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
				found_our_static_ptr \|= info->found_our_static_ptr;
				found_any_static_type \|= info->found_any_static_type;
				} while (++p < e);
				}
				// Restore flags
				info->found_our_static_ptr = found_our_static_ptr;
				info->found_any_static_type = found_any_static_type;
				}
				}

				// This is the same algorithm as __vmi_class_type_info::search_above_dst but
				// simplified to the case that there is only a single base class.
				void
				__si_class_type_info::search_above_dst(__dynamic_cast_info* info,
				const void* dst_ptr,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				if (is_equal(this, info->static_type, use_strcmp))
				process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
				else
				__base_type->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
				}

				// This is the same algorithm as __vmi_class_type_info::search_above_dst but
				// simplified to the case that there is no base class.
				void
				__class_type_info::search_above_dst(__dynamic_cast_info* info,
				const void* dst_ptr,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				if (is_equal(this, info->static_type, use_strcmp))
				process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
				}

				// The search functions for __base_class_type_info are simply convenience
				// functions for adjusting the current_ptr and path_below as the search is
				// passed up to the base class node.

				void
				__base_class_type_info::search_above_dst(__dynamic_cast_info* info,
				const void* dst_ptr,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
				if (__offset_flags & __virtual_mask)
				{
				const char* vtable = static_cast<const charconst*>(current_ptr);
				offset_to_base = reinterpret_cast<const ptrdiff_t>(vtable + offset_to_base);
				}
				__base_type->search_above_dst(info, dst_ptr,
				static_cast<const char*>(current_ptr) + offset_to_base,
				(__offset_flags & __public_mask) ?
				path_below :
				not_public_path,
				use_strcmp);
				}

				void
				__base_class_type_info::search_below_dst(__dynamic_cast_info* info,
				const void* current_ptr,
				int path_below,
				bool use_strcmp) const
				{
				ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
				if (__offset_flags & __virtual_mask)
				{
				const char* vtable = static_cast<const charconst*>(current_ptr);
				offset_to_base = reinterpret_cast<const ptrdiff_t>(vtable + offset_to_base);
				}
				__base_type->search_below_dst(info,
				static_cast<const char*>(current_ptr) + offset_to_base,
				(__offset_flags & __public_mask) ?
				path_below :
				not_public_path,
				use_strcmp);
				}

				} // __cxxabiv1