532 lines
15 KiB
C++
532 lines
15 KiB
C++
// <system_error> -*- C++ -*-
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// Copyright (C) 2007-2022 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file include/system_error
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* This is a Standard C++ Library header.
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*/
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#ifndef _GLIBCXX_SYSTEM_ERROR
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#define _GLIBCXX_SYSTEM_ERROR 1
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#pragma GCC system_header
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#if __cplusplus < 201103L
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# include <bits/c++0x_warning.h>
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#else
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#include <bits/c++config.h>
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#include <bits/error_constants.h>
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#include <iosfwd>
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#include <stdexcept>
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#if __cplusplus > 201703L
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# include <compare>
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#endif
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/** @addtogroup diagnostics
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* @{
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*/
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class error_code;
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class error_condition;
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class system_error;
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/// is_error_code_enum
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template<typename _Tp>
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struct is_error_code_enum : public false_type { };
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/// is_error_condition_enum
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template<typename _Tp>
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struct is_error_condition_enum : public false_type { };
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template<>
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struct is_error_condition_enum<errc>
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: public true_type { };
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#if __cplusplus > 201402L
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template <typename _Tp>
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inline constexpr bool is_error_code_enum_v =
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is_error_code_enum<_Tp>::value;
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template <typename _Tp>
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inline constexpr bool is_error_condition_enum_v =
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is_error_condition_enum<_Tp>::value;
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#endif // C++17
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/// @}
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inline namespace _V2 {
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/** @addtogroup diagnostics
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* @{
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*/
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/** Abstract base class for types defining a category of error codes.
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*
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* An error category defines a context that give meaning to the integer
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* stored in an `error_code` or `error_condition` object. For example,
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* the standard `errno` constants such a `EINVAL` and `ENOMEM` are
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* associated with the "generic" category and other OS-specific error
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* numbers are associated with the "system" category, but a user-defined
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* category might give different meanings to the same numerical values.
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*
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* @since C++11
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*/
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class error_category
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{
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public:
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constexpr error_category() noexcept = default;
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virtual ~error_category();
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error_category(const error_category&) = delete;
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error_category& operator=(const error_category&) = delete;
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virtual const char*
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name() const noexcept = 0;
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// We need two different virtual functions here, one returning a
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// COW string and one returning an SSO string. Their positions in the
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// vtable must be consistent for dynamic dispatch to work, but which one
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// the name "message()" finds depends on which ABI the caller is using.
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#if _GLIBCXX_USE_CXX11_ABI
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private:
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_GLIBCXX_DEFAULT_ABI_TAG
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virtual __cow_string
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_M_message(int) const;
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public:
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_GLIBCXX_DEFAULT_ABI_TAG
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virtual string
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message(int) const = 0;
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#else
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virtual string
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message(int) const = 0;
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private:
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virtual __sso_string
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_M_message(int) const;
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#endif
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public:
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virtual error_condition
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default_error_condition(int __i) const noexcept;
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virtual bool
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equivalent(int __i, const error_condition& __cond) const noexcept;
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virtual bool
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equivalent(const error_code& __code, int __i) const noexcept;
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bool
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operator==(const error_category& __other) const noexcept
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{ return this == &__other; }
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#if __cpp_lib_three_way_comparison
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strong_ordering
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operator<=>(const error_category& __rhs) const noexcept
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{ return std::compare_three_way()(this, &__rhs); }
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#else
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bool
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operator!=(const error_category& __other) const noexcept
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{ return this != &__other; }
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bool
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operator<(const error_category& __other) const noexcept
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{ return less<const error_category*>()(this, &__other); }
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#endif
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};
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// DR 890.
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/// Error category for `errno` error codes.
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_GLIBCXX_CONST const error_category& generic_category() noexcept;
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/// Error category for other error codes defined by the OS.
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_GLIBCXX_CONST const error_category& system_category() noexcept;
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/// @}
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} // end inline namespace
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/** @addtogroup diagnostics
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* @{
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*/
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error_code make_error_code(errc) noexcept;
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/** Class error_code
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*
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* This class is a value type storing an integer error number and a
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* category that gives meaning to the error number. Typically this is done
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* close the the point where the error happens, to capture the original
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* error value.
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*
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* An `error_code` object can be used to store the original error value
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* emitted by some subsystem, with a category relevant to the subsystem.
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* For example, errors from POSIX library functions can be represented by
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* an `errno` value and the "generic" category, but errors from an HTTP
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* library might be represented by an HTTP response status code (e.g. 404)
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* and a custom category defined by the library.
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*
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* @since C++11
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* @ingroup diagnostics
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*/
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class error_code
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{
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public:
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error_code() noexcept
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: _M_value(0), _M_cat(&system_category()) { }
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error_code(int __v, const error_category& __cat) noexcept
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: _M_value(__v), _M_cat(&__cat) { }
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template<typename _ErrorCodeEnum, typename = typename
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enable_if<is_error_code_enum<_ErrorCodeEnum>::value>::type>
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error_code(_ErrorCodeEnum __e) noexcept
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{ *this = make_error_code(__e); }
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void
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assign(int __v, const error_category& __cat) noexcept
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{
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_M_value = __v;
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_M_cat = &__cat;
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}
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void
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clear() noexcept
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{ assign(0, system_category()); }
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// DR 804.
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template<typename _ErrorCodeEnum>
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typename enable_if<is_error_code_enum<_ErrorCodeEnum>::value,
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error_code&>::type
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operator=(_ErrorCodeEnum __e) noexcept
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{ return *this = make_error_code(__e); }
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int
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value() const noexcept { return _M_value; }
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const error_category&
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category() const noexcept { return *_M_cat; }
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error_condition
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default_error_condition() const noexcept;
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_GLIBCXX_DEFAULT_ABI_TAG
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string
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message() const
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{ return category().message(value()); }
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explicit operator bool() const noexcept
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{ return _M_value != 0; }
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// DR 804.
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private:
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int _M_value;
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const error_category* _M_cat;
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};
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// 19.4.2.6 non-member functions
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/// @relates error_code @{
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inline error_code
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make_error_code(errc __e) noexcept
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{ return error_code(static_cast<int>(__e), generic_category()); }
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#if __cpp_lib_three_way_comparison
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inline strong_ordering
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operator<=>(const error_code& __lhs, const error_code& __rhs) noexcept
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{
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if (auto __c = __lhs.category() <=> __rhs.category(); __c != 0)
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return __c;
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return __lhs.value() <=> __rhs.value();
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}
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#else
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inline bool
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operator<(const error_code& __lhs, const error_code& __rhs) noexcept
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{
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return (__lhs.category() < __rhs.category()
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|| (__lhs.category() == __rhs.category()
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&& __lhs.value() < __rhs.value()));
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}
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#endif
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template<typename _CharT, typename _Traits>
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os, const error_code& __e)
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{ return (__os << __e.category().name() << ':' << __e.value()); }
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/// @}
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error_condition make_error_condition(errc) noexcept;
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/** Class error_condition
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*
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* This class represents error conditions that may be visible at an API
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* boundary. Different `error_code` values that can occur within a library
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* or module might map to the same `error_condition`.
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*
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* An `error_condition` represents something that the program can test for,
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* and subsequently take appropriate action.
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*
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* @since C++11
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*/
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class error_condition
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{
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public:
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error_condition() noexcept
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: _M_value(0), _M_cat(&generic_category()) { }
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error_condition(int __v, const error_category& __cat) noexcept
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: _M_value(__v), _M_cat(&__cat) { }
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template<typename _ErrorConditionEnum, typename = typename
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enable_if<is_error_condition_enum<_ErrorConditionEnum>::value>::type>
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error_condition(_ErrorConditionEnum __e) noexcept
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{ *this = make_error_condition(__e); }
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void
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assign(int __v, const error_category& __cat) noexcept
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{
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_M_value = __v;
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_M_cat = &__cat;
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}
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// DR 804.
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template<typename _ErrorConditionEnum>
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typename enable_if<is_error_condition_enum
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<_ErrorConditionEnum>::value, error_condition&>::type
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operator=(_ErrorConditionEnum __e) noexcept
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{ return *this = make_error_condition(__e); }
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void
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clear() noexcept
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{ assign(0, generic_category()); }
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// 19.4.3.4 observers
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int
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value() const noexcept { return _M_value; }
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const error_category&
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category() const noexcept { return *_M_cat; }
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_GLIBCXX_DEFAULT_ABI_TAG
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string
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message() const
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{ return category().message(value()); }
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explicit operator bool() const noexcept
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{ return _M_value != 0; }
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// DR 804.
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private:
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int _M_value;
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const error_category* _M_cat;
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};
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// 19.4.3.6 non-member functions
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/// Create an `error_condition` representing a standard `errc` condition.
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/// @relates error_condition
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inline error_condition
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make_error_condition(errc __e) noexcept
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{ return error_condition(static_cast<int>(__e), generic_category()); }
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// 19.4.4 Comparison operators
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/// @relates error_code
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inline bool
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operator==(const error_code& __lhs, const error_code& __rhs) noexcept
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{ return (__lhs.category() == __rhs.category()
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&& __lhs.value() == __rhs.value()); }
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/// @relates error_code
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inline bool
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operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
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{
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return (__lhs.category().equivalent(__lhs.value(), __rhs)
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|| __rhs.category().equivalent(__lhs, __rhs.value()));
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}
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/// @relates error_condition
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inline bool
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operator==(const error_condition& __lhs,
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const error_condition& __rhs) noexcept
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{
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return (__lhs.category() == __rhs.category()
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&& __lhs.value() == __rhs.value());
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}
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#if __cpp_lib_three_way_comparison
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/// Define an ordering for error_condition objects.
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/// @relates error_condition
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inline strong_ordering
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operator<=>(const error_condition& __lhs,
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const error_condition& __rhs) noexcept
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{
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if (auto __c = __lhs.category() <=> __rhs.category(); __c != 0)
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return __c;
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return __lhs.value() <=> __rhs.value();
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}
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#else
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/// Define an ordering for error_condition objects.
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/// @relates error_condition
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inline bool
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operator<(const error_condition& __lhs,
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const error_condition& __rhs) noexcept
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{
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return (__lhs.category() < __rhs.category()
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|| (__lhs.category() == __rhs.category()
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&& __lhs.value() < __rhs.value()));
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}
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/// @relates error_condition
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inline bool
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operator==(const error_condition& __lhs, const error_code& __rhs) noexcept
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{
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return (__rhs.category().equivalent(__rhs.value(), __lhs)
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|| __lhs.category().equivalent(__rhs, __lhs.value()));
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}
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/// @relates error_code
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inline bool
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operator!=(const error_code& __lhs, const error_code& __rhs) noexcept
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{ return !(__lhs == __rhs); }
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/// @relates error_code
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inline bool
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operator!=(const error_code& __lhs, const error_condition& __rhs) noexcept
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{ return !(__lhs == __rhs); }
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/// @relates error_condition
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inline bool
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operator!=(const error_condition& __lhs, const error_code& __rhs) noexcept
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{ return !(__lhs == __rhs); }
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/// @relates error_condition
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inline bool
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operator!=(const error_condition& __lhs,
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const error_condition& __rhs) noexcept
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{ return !(__lhs == __rhs); }
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#endif // three_way_comparison
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/// @}
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/**
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* @brief An exception type that includes an `error_code` value.
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*
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* Typically used to report errors from the operating system and other
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* low-level APIs.
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*
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* @since C++11
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* @ingroup exceptions
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*/
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class system_error : public std::runtime_error
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{
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private:
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error_code _M_code;
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public:
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system_error(error_code __ec = error_code())
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: runtime_error(__ec.message()), _M_code(__ec) { }
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system_error(error_code __ec, const string& __what)
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: runtime_error(__what + ": " + __ec.message()), _M_code(__ec) { }
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system_error(error_code __ec, const char* __what)
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: runtime_error(__what + (": " + __ec.message())), _M_code(__ec) { }
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system_error(int __v, const error_category& __ecat, const char* __what)
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: system_error(error_code(__v, __ecat), __what) { }
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system_error(int __v, const error_category& __ecat)
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: runtime_error(error_code(__v, __ecat).message()),
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_M_code(__v, __ecat) { }
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system_error(int __v, const error_category& __ecat, const string& __what)
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: runtime_error(__what + ": " + error_code(__v, __ecat).message()),
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_M_code(__v, __ecat) { }
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#if __cplusplus >= 201103L
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system_error (const system_error &) = default;
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system_error &operator= (const system_error &) = default;
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#endif
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virtual ~system_error() noexcept;
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const error_code&
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code() const noexcept { return _M_code; }
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};
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#include <bits/functional_hash.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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#ifndef _GLIBCXX_COMPATIBILITY_CXX0X
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// DR 1182.
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/// std::hash specialization for error_code.
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/// @relates error_code
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template<>
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struct hash<error_code>
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: public __hash_base<size_t, error_code>
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{
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size_t
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operator()(const error_code& __e) const noexcept
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{
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const size_t __tmp = std::_Hash_impl::hash(__e.value());
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return std::_Hash_impl::__hash_combine(&__e.category(), __tmp);
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}
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};
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#endif // _GLIBCXX_COMPATIBILITY_CXX0X
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#if __cplusplus >= 201703L
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// DR 2686.
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/// std::hash specialization for error_condition.
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/// @relates error_condition
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template<>
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struct hash<error_condition>
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: public __hash_base<size_t, error_condition>
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{
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size_t
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operator()(const error_condition& __e) const noexcept
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{
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const size_t __tmp = std::_Hash_impl::hash(__e.value());
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return std::_Hash_impl::__hash_combine(&__e.category(), __tmp);
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}
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};
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#endif
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#endif // C++11
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#endif // _GLIBCXX_SYSTEM_ERROR
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