babaabbcc8
This defines std::unreachable as an assertion for debug mode, a trap when _GLIBCXX_ASSERTIONS is defined, and __builtin_unreachable() otherwise. The reason for only using __builtin_trap() in the second case is to avoid the overhead of setting up a call to __glibcxx_assert_fail that should never happen. UBsan can detect if __builtin_unreachable() is executed, so if a feature test macro for that sanitizer is added, we could change just use __builtin_unreachable() when the sanitizer is enabled. While thinking about what the debug assertion failure should print, I noticed that the __glibcxx_assert_fail function doesn't check for null pointers. This adds a check so we don't try to print them if null. libstdc++-v3/ChangeLog: * include/std/utility (unreachable): Define for C++23. * include/std/version (__cpp_lib_unreachable): Define. * src/c++11/debug.cc (__glibcxx_assert_fail): Check for valid arguments. Handle only the function being given. * testsuite/20_util/unreachable/1.cc: New test. * testsuite/20_util/unreachable/version.cc: New test.
226 lines
6.9 KiB
C++
226 lines
6.9 KiB
C++
// <utility> -*- C++ -*-
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// Copyright (C) 2001-2022 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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/*
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*
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* Copyright (c) 1994
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* Hewlett-Packard Company
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Hewlett-Packard Company makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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*
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* Copyright (c) 1996,1997
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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/** @file include/utility
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* This is a Standard C++ Library header.
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*/
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#ifndef _GLIBCXX_UTILITY
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#define _GLIBCXX_UTILITY 1
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#pragma GCC system_header
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/**
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* @defgroup utilities Utilities
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*
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* Basic function and class templates used with the rest of the library.
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* Includes pair, swap, forward/move helpers, declval, integer_sequence.
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*/
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#include <bits/c++config.h>
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#include <bits/stl_relops.h>
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#include <bits/stl_pair.h>
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#if __cplusplus >= 201103L
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#include <initializer_list>
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#include <type_traits>
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#include <bits/move.h>
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#include <bits/utility.h>
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#if __cplusplus >= 202002L
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#include <ext/numeric_traits.h> // __is_standard_integer, __int_traits
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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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#if __cplusplus >= 201402L
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#define __cpp_lib_exchange_function 201304L
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/// Assign @p __new_val to @p __obj and return its previous value.
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template <typename _Tp, typename _Up = _Tp>
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_GLIBCXX20_CONSTEXPR
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inline _Tp
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exchange(_Tp& __obj, _Up&& __new_val)
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noexcept(__and_<is_nothrow_move_constructible<_Tp>,
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is_nothrow_assignable<_Tp&, _Up>>::value)
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{ return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
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#if __cplusplus >= 201703L
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#define __cpp_lib_as_const 201510L
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template<typename _Tp>
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[[nodiscard]]
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constexpr add_const_t<_Tp>&
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as_const(_Tp& __t) noexcept
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{ return __t; }
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template<typename _Tp>
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void as_const(const _Tp&&) = delete;
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#if __cplusplus > 201703L
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#define __cpp_lib_integer_comparison_functions 202002L
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template<typename _Tp, typename _Up>
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constexpr bool
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cmp_equal(_Tp __t, _Up __u) noexcept
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{
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static_assert(__is_standard_integer<_Tp>::value);
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static_assert(__is_standard_integer<_Up>::value);
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if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
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return __t == __u;
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else if constexpr (is_signed_v<_Tp>)
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return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u;
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else
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return __u >= 0 && __t == make_unsigned_t<_Up>(__u);
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}
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template<typename _Tp, typename _Up>
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constexpr bool
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cmp_not_equal(_Tp __t, _Up __u) noexcept
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{ return !std::cmp_equal(__t, __u); }
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template<typename _Tp, typename _Up>
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constexpr bool
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cmp_less(_Tp __t, _Up __u) noexcept
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{
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static_assert(__is_standard_integer<_Tp>::value);
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static_assert(__is_standard_integer<_Up>::value);
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if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
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return __t < __u;
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else if constexpr (is_signed_v<_Tp>)
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return __t < 0 || make_unsigned_t<_Tp>(__t) < __u;
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else
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return __u >= 0 && __t < make_unsigned_t<_Up>(__u);
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}
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template<typename _Tp, typename _Up>
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constexpr bool
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cmp_greater(_Tp __t, _Up __u) noexcept
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{ return std::cmp_less(__u, __t); }
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template<typename _Tp, typename _Up>
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constexpr bool
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cmp_less_equal(_Tp __t, _Up __u) noexcept
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{ return !std::cmp_less(__u, __t); }
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template<typename _Tp, typename _Up>
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constexpr bool
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cmp_greater_equal(_Tp __t, _Up __u) noexcept
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{ return !std::cmp_less(__t, __u); }
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template<typename _Up, typename _Tp>
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constexpr bool
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in_range(_Tp __t) noexcept
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{
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static_assert(__is_standard_integer<_Up>::value);
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static_assert(__is_standard_integer<_Tp>::value);
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using __gnu_cxx::__int_traits;
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if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
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return __int_traits<_Up>::__min <= __t
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&& __t <= __int_traits<_Up>::__max;
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else if constexpr (is_signed_v<_Tp>)
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return __t >= 0
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&& make_unsigned_t<_Tp>(__t) <= __int_traits<_Up>::__max;
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else
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return __t <= make_unsigned_t<_Up>(__int_traits<_Up>::__max);
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}
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#if __cplusplus > 202002L
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#define __cpp_lib_to_underlying 202102L
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/// Convert an object of enumeration type to its underlying type.
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template<typename _Tp>
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[[nodiscard]]
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constexpr underlying_type_t<_Tp>
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to_underlying(_Tp __value) noexcept
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{ return static_cast<underlying_type_t<_Tp>>(__value); }
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#define __cpp_lib_unreachable 202202L
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/// Informs the compiler that program control flow never reaches this point.
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/**
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* Evaluating a call to this function results in undefined behaviour.
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* This can be used as an assertion informing the compiler that certain
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* conditions are impossible, for when the compiler is unable to determine
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* that by itself.
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*
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* For example, it can be used to prevent warnings about reaching the
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* end of a non-void function without returning.
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*
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* @since C++23
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*/
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[[noreturn,__gnu__::__always_inline__]]
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inline void
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unreachable()
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{
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#ifdef _GLIBCXX_DEBUG
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std::__glibcxx_assert_fail(nullptr, 0, "std::unreachable()", nullptr);
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#elif defined _GLIBCXX_ASSERTIONS
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__builtin_trap();
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#else
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__builtin_unreachable();
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#endif
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}
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#endif // C++23
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#endif // C++20
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#endif // C++17
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#endif // C++14
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#endif
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#endif /* _GLIBCXX_UTILITY */
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