typeinfo | Explore in Territory

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_TYPEINFO
#define _LIBCPP_TYPEINFO

/*

    typeinfo synopsis

namespace std {

class type_info
{
public:
    virtual ~type_info();

    bool operator==(const type_info& rhs) const noexcept; // constexpr since C++23
    bool operator!=(const type_info& rhs) const noexcept; // removed in C++20

    bool before(const type_info& rhs) const noexcept;
    size_t hash_code() const noexcept;
    const char* name() const noexcept;

    type_info(const type_info& rhs) = delete;
    type_info& operator=(const type_info& rhs) = delete;
};

class bad_cast
    : public exception
{
public:
    bad_cast() noexcept;
    bad_cast(const bad_cast&) noexcept;
    bad_cast& operator=(const bad_cast&) noexcept;
    virtual const char* what() const noexcept;
};

class bad_typeid
    : public exception
{
public:
    bad_typeid() noexcept;
    bad_typeid(const bad_typeid&) noexcept;
    bad_typeid& operator=(const bad_typeid&) noexcept;
    virtual const char* what() const noexcept;
};

}  // std

*/

#include <__config>
#include <__exception/exception.h>
#include <__type_traits/is_constant_evaluated.h>
#include <__verbose_abort>
#include <cstddef>
#include <cstdint>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

#if defined(_LIBCPP_ABI_VCRUNTIME)
#  include <vcruntime_typeinfo.h>
#else

namespace std // purposefully not using versioning namespace
{

#  if defined(_LIBCPP_ABI_MICROSOFT)

class _LIBCPP_EXPORTED_FROM_ABI type_info {
  type_info& operator=(const type_info&);
  type_info(const type_info&);

  mutable struct {
    const char* __undecorated_name;
    const char __decorated_name[1];
  } __data;

  int __compare(const type_info& __rhs) const _NOEXCEPT;

public:
  virtual ~type_info();

  const char* name() const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI bool before(const type_info& __arg) const _NOEXCEPT { return __compare(__arg) < 0; }

  size_t hash_code() const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
    // When evaluated in a constant expression, both type infos simply can't come
    // from different translation units, so it is sufficient to compare their addresses.
    if (__libcpp_is_constant_evaluated()) {
      return this == &__arg;
    }
    return __compare(__arg) == 0;
  }

#    if _LIBCPP_STD_VER <= 17
  _LIBCPP_HIDE_FROM_ABI bool operator!=(const type_info& __arg) const _NOEXCEPT { return !operator==(__arg); }
#    endif
};

#  else // !defined(_LIBCPP_ABI_MICROSOFT)

// ========================================================================== //
//                           Implementations
// ========================================================================== //
// ------------------------------------------------------------------------- //
//                               Unique
//               (_LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION = 1)
// ------------------------------------------------------------------------- //
// This implementation of type_info assumes a unique copy of the RTTI for a
// given type inside a program. This is a valid assumption when abiding to the
// Itanium ABI (http://itanium-cxx-abi.github.io/cxx-abi/abi.html#vtable-components).
// Under this assumption, we can always compare the addresses of the type names
// to implement equality-comparison of type_infos instead of having to perform
// a deep string comparison.
// -------------------------------------------------------------------------- //
//                             NonUnique
//               (_LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION = 2)
// -------------------------------------------------------------------------- //
// This implementation of type_info does not assume there is always a unique
// copy of the RTTI for a given type inside a program. For various reasons
// the linker may have failed to merge every copy of a types RTTI
// (For example: -Bsymbolic or llvm.org/PR37398). Under this assumption, two
// type_infos are equal if their addresses are equal or if a deep string
// comparison is equal.
// -------------------------------------------------------------------------- //
//                          NonUniqueARMRTTIBit
//               (_LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION = 3)
// -------------------------------------------------------------------------- //
// This implementation is specific to ARM64 on Apple platforms.
//
// This implementation of type_info does not assume always a unique copy of
// the RTTI for a given type inside a program. When constructing the type_info,
// the compiler packs the pointer to the type name into a uintptr_t and reserves
// the high bit of that pointer, which is assumed to be free for use under that
// ABI. If that high bit is set, that specific copy of the RTTI can't be assumed
// to be unique within the program. If the high bit is unset, then the RTTI can
// be assumed to be unique within the program.
//
// When comparing type_infos, if both RTTIs can be assumed to be unique, it
// suffices to compare their addresses. If both the RTTIs can't be assumed to
// be unique, we must perform a deep string comparison of the type names.
// However, if one of the RTTIs is guaranteed unique and the other one isn't,
// then both RTTIs are necessarily not to be considered equal.
//
// The intent of this design is to remove the need for weak symbols. Specifically,
// if a type would normally have a default-visibility RTTI emitted as a weak
// symbol, it is given hidden visibility instead and the non-unique bit is set.
// Otherwise, types declared with hidden visibility are always considered to have
// a unique RTTI: the RTTI is emitted with linkonce_odr linkage and is assumed
// to be deduplicated by the linker within the linked image. Across linked image
// boundaries, such types are thus considered different types.

// This value can be overriden in the __config_site. When it's not overriden,
// we pick a default implementation based on the platform here.
#    ifndef _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION

// Windows and AIX binaries can't merge typeinfos, so use the NonUnique implementation.
#      if defined(_LIBCPP_OBJECT_FORMAT_COFF) || defined(_LIBCPP_OBJECT_FORMAT_XCOFF)
#define _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION …

// On arm64 on Apple platforms, use the special NonUniqueARMRTTIBit implementation.
#      elif defined(__APPLE__) && defined(__LP64__) && !defined(__x86_64__)
#define _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION …

// On all other platforms, assume the Itanium C++ ABI and use the Unique implementation.
#      else
#define _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION …
#      endif
#    endif

struct __type_info_implementations { … };

#    if __has_cpp_attribute(_Clang::__ptrauth_vtable_pointer__)
#      if __has_feature(ptrauth_type_info_vtable_pointer_discrimination)
#define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH …
#      else
#define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH …
#      endif
#    else
#define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH
#    endif

class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH type_info { … };
#  endif // defined(_LIBCPP_ABI_MICROSOFT)

class _LIBCPP_EXPORTED_FROM_ABI bad_cast : public exception { … };

class _LIBCPP_EXPORTED_FROM_ABI bad_typeid : public exception { … };

} // namespace std

#endif // defined(_LIBCPP_ABI_VCRUNTIME)

#if defined(_LIBCPP_ABI_VCRUNTIME) && _HAS_EXCEPTIONS == 0

namespace std {

class bad_cast : public exception {
public:
  bad_cast() _NOEXCEPT : exception("bad cast") {}

private:
  bad_cast(const char* const __message) _NOEXCEPT : exception(__message) {}
};

class bad_typeid : public exception {
public:
  bad_typeid() _NOEXCEPT : exception("bad typeid") {}

private:
  bad_typeid(const char* const __message) _NOEXCEPT : exception(__message) {}
};

} // namespace std

#endif // defined(_LIBCPP_ABI_VCRUNTIME) && _HAS_EXCEPTIONS == 0

_LIBCPP_BEGIN_NAMESPACE_STD
_LIBCPP_NORETURN inline _LIBCPP_HIDE_FROM_ABI void __throw_bad_cast() { … }
_LIBCPP_END_NAMESPACE_STD

#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
#  include <cstdlib>
#  include <type_traits>
#endif

#endif // _LIBCPP_TYPEINFO
chromium/third_party/libc++/src/include/typeinfo
