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// Nested Exception support header (nested_exception class) for -*- C++ -*-
// Copyright (C) 2009-2021 Free Software Foundation, Inc.
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <>.
/** @file bits/nested_exception.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{exception}
#pragma GCC visibility push(default)
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#include <bits/c++config.h>
#include <bits/move.h>
extern "C++" {
namespace std
* @addtogroup exceptions
* @{
/// Exception class with exception_ptr data member.
class nested_exception
exception_ptr _M_ptr;
nested_exception() noexcept : _M_ptr(current_exception()) { }
nested_exception(const nested_exception&) noexcept = default;
nested_exception& operator=(const nested_exception&) noexcept = default;
virtual ~nested_exception() noexcept;
rethrow_nested() const
if (_M_ptr)
nested_ptr() const noexcept
{ return _M_ptr; }
/// @cond undocumented
template<typename _Except>
struct _Nested_exception : public _Except, public nested_exception
explicit _Nested_exception(const _Except& __ex)
: _Except(__ex)
{ }
explicit _Nested_exception(_Except&& __ex)
: _Except(static_cast<_Except&&>(__ex))
{ }
// [except.nested]/8
// Throw an exception of unspecified type that is publicly derived from
// both remove_reference_t<_Tp> and nested_exception.
template<typename _Tp>
inline void
__throw_with_nested_impl(_Tp&& __t, true_type)
using _Up = typename remove_reference<_Tp>::type;
throw _Nested_exception<_Up>{std::forward<_Tp>(__t)};
template<typename _Tp>
inline void
__throw_with_nested_impl(_Tp&& __t, false_type)
{ throw std::forward<_Tp>(__t); }
/// @endcond
/// If @p __t is derived from nested_exception, throws @p __t.
/// Else, throws an implementation-defined object derived from both.
template<typename _Tp>
inline void
throw_with_nested(_Tp&& __t)
using _Up = typename decay<_Tp>::type;
using _CopyConstructible
= __and_<is_copy_constructible<_Up>, is_move_constructible<_Up>>;
"throw_with_nested argument must be CopyConstructible");
using __nest = __and_<is_class<_Up>, __bool_constant<!__is_final(_Up)>,
__not_<is_base_of<nested_exception, _Up>>>;
std::__throw_with_nested_impl(std::forward<_Tp>(__t), __nest{});
/// @cond undocumented
// Determine if dynamic_cast<const nested_exception&> would be well-formed.
template<typename _Tp>
using __rethrow_if_nested_cond = typename enable_if<
__or_<__not_<is_base_of<nested_exception, _Tp>>,
is_convertible<_Tp*, nested_exception*>>>::value
// Attempt dynamic_cast to nested_exception and call rethrow_nested().
template<typename _Ex>
inline __rethrow_if_nested_cond<_Ex>
__rethrow_if_nested_impl(const _Ex* __ptr)
if (auto __ne_ptr = dynamic_cast<const nested_exception*>(__ptr))
// Otherwise, no effects.
inline void
__rethrow_if_nested_impl(const void*)
{ }
/// @endcond
/// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested().
template<typename _Ex>
inline void
rethrow_if_nested(const _Ex& __ex)
{ std::__rethrow_if_nested_impl(std::__addressof(__ex)); }
/// @} group exceptions
} // namespace std
} // extern "C++"
#endif // C++11
#pragma GCC visibility pop