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8aff55e259
The if-consteval branches in std::make_exception_ptr and std::exception_ptr_cast use a try-catch block, which gives an error for -fno-exceptions. Just make them return a null pointer at compile-time when -fno-exceptions is used, because there's no way to get an active exception with -fno-exceptions. For both functions we have a runtime-only branch that depends on RTTI, and a fallback using try-catch which works for runtime and consteval. Rearrange both functions to express this logic more clearly. Also adjust some formatting and whitespace elsewhere in the file. libstdc++-v3/ChangeLog: * libsupc++/exception_ptr.h (make_exception_ptr): Return null for consteval when -fno-exceptions is used. (exception_ptr_cast): Likewise. Allow consteval path to work with -fno-rtti. Reviewed-by: Jakub Jelinek <jakub@redhat.com>
394 lines
11 KiB
C++
394 lines
11 KiB
C++
// Exception Handling support header (exception_ptr class) for -*- C++ -*-
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// Copyright (C) 2008-2025 Free Software Foundation, Inc.
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//
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// This file is part of GCC.
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//
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// GCC is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3, or (at your option)
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// any later version.
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//
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// GCC 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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//
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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 bits/exception_ptr.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{exception}
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*/
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#ifndef _EXCEPTION_PTR_H
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#define _EXCEPTION_PTR_H
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#include <bits/c++config.h>
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#include <bits/exception_defines.h>
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#include <bits/cxxabi_init_exception.h>
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#include <typeinfo>
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#include <new>
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#if __cplusplus >= 201103L
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# include <bits/move.h>
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#endif
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#ifdef _GLIBCXX_EH_PTR_RELOPS_COMPAT
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# define _GLIBCXX_EH_PTR_USED __attribute__((__used__))
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#else
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# define _GLIBCXX_EH_PTR_USED
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#endif
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extern "C++" {
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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class type_info;
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/**
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* @addtogroup exceptions
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* @{
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*/
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namespace __exception_ptr
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{
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class exception_ptr;
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}
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using __exception_ptr::exception_ptr;
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/** Obtain an exception_ptr to the currently handled exception.
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*
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* If there is none, or the currently handled exception is foreign,
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* return the null value.
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*
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* @since C++11
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*/
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exception_ptr current_exception() _GLIBCXX_USE_NOEXCEPT;
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template<typename _Ex>
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_GLIBCXX26_CONSTEXPR exception_ptr make_exception_ptr(_Ex)
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_GLIBCXX_USE_NOEXCEPT;
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/// Throw the object pointed to by the exception_ptr.
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void rethrow_exception(exception_ptr) __attribute__ ((__noreturn__));
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#if __cpp_lib_exception_ptr_cast >= 202506L
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template<typename _Ex>
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constexpr const _Ex* exception_ptr_cast(const exception_ptr&) noexcept;
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template<typename _Ex>
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void exception_ptr_cast(const exception_ptr&&) = delete;
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#endif
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namespace __exception_ptr
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{
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using std::rethrow_exception; // So that ADL finds it.
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/**
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* @brief An opaque pointer to an arbitrary exception.
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*
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* The actual name of this type is unspecified, so the alias
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* `std::exception_ptr` should be used to refer to it.
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*
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* @headerfile exception
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* @since C++11 (but usable in C++98 as a GCC extension)
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* @ingroup exceptions
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*/
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class exception_ptr
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{
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void* _M_exception_object;
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#if __cplusplus >= 202400L
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constexpr explicit exception_ptr(void* __e) noexcept
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: _M_exception_object(__e)
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{
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if (_M_exception_object)
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{
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#if __cpp_if_consteval >= 202106L \
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&& _GLIBCXX_HAS_BUILTIN(__builtin_eh_ptr_adjust_ref)
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if consteval {
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__builtin_eh_ptr_adjust_ref(_M_exception_object, 1);
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return;
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}
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#endif
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_M_addref();
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}
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}
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#else
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explicit exception_ptr(void* __e) _GLIBCXX_USE_NOEXCEPT;
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#endif
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void _M_addref() _GLIBCXX_USE_NOEXCEPT;
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void _M_release() _GLIBCXX_USE_NOEXCEPT;
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void *_M_get() const _GLIBCXX_NOEXCEPT __attribute__ ((__pure__));
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friend exception_ptr std::current_exception() _GLIBCXX_USE_NOEXCEPT;
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friend void std::rethrow_exception(exception_ptr);
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template<typename _Ex>
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friend _GLIBCXX26_CONSTEXPR exception_ptr std::make_exception_ptr(_Ex)
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_GLIBCXX_USE_NOEXCEPT;
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#if __cpp_lib_exception_ptr_cast >= 202506L
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template<typename _Ex>
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friend constexpr const _Ex*
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std::exception_ptr_cast(const exception_ptr&) noexcept;
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#endif
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const void* _M_exception_ptr_cast(const type_info&) const
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_GLIBCXX_USE_NOEXCEPT;
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public:
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_GLIBCXX26_CONSTEXPR exception_ptr() _GLIBCXX_USE_NOEXCEPT;
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_GLIBCXX26_CONSTEXPR exception_ptr(const exception_ptr&)
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_GLIBCXX_USE_NOEXCEPT;
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#if __cplusplus >= 201103L
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_GLIBCXX26_CONSTEXPR exception_ptr(nullptr_t) noexcept
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: _M_exception_object(nullptr)
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{ }
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_GLIBCXX26_CONSTEXPR exception_ptr(exception_ptr&& __o) noexcept
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: _M_exception_object(__o._M_exception_object)
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{ __o._M_exception_object = nullptr; }
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#endif
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#if (__cplusplus < 201103L) || defined (_GLIBCXX_EH_PTR_COMPAT)
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typedef void (exception_ptr::*__safe_bool)();
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// For construction from nullptr or 0.
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exception_ptr(__safe_bool) _GLIBCXX_USE_NOEXCEPT;
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#endif
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_GLIBCXX26_CONSTEXPR exception_ptr&
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operator=(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
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#if __cplusplus >= 201103L
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_GLIBCXX26_CONSTEXPR exception_ptr&
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operator=(exception_ptr&& __o) noexcept
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{
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exception_ptr(static_cast<exception_ptr&&>(__o)).swap(*this);
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return *this;
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}
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#endif
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_GLIBCXX26_CONSTEXPR ~exception_ptr() _GLIBCXX_USE_NOEXCEPT;
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_GLIBCXX26_CONSTEXPR void
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swap(exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
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#ifdef _GLIBCXX_EH_PTR_COMPAT
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// Retained for compatibility with CXXABI_1.3.
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void _M_safe_bool_dummy() _GLIBCXX_USE_NOEXCEPT;
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bool operator!() const _GLIBCXX_USE_NOEXCEPT
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__attribute__ ((__pure__));
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operator __safe_bool() const _GLIBCXX_USE_NOEXCEPT;
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#endif
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#if __cplusplus >= 201103L
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_GLIBCXX26_CONSTEXPR explicit operator bool() const noexcept
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{ return _M_exception_object; }
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#endif
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#if __cpp_impl_three_way_comparison >= 201907L \
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&& ! defined _GLIBCXX_EH_PTR_RELOPS_COMPAT
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_GLIBCXX26_CONSTEXPR friend bool
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operator==(const exception_ptr&, const exception_ptr&) noexcept = default;
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#else
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friend _GLIBCXX_EH_PTR_USED bool
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operator==(const exception_ptr& __x, const exception_ptr& __y)
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_GLIBCXX_USE_NOEXCEPT
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{ return __x._M_exception_object == __y._M_exception_object; }
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friend _GLIBCXX_EH_PTR_USED bool
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operator!=(const exception_ptr& __x, const exception_ptr& __y)
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_GLIBCXX_USE_NOEXCEPT
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{ return __x._M_exception_object != __y._M_exception_object; }
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#endif
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const class std::type_info*
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__cxa_exception_type() const _GLIBCXX_USE_NOEXCEPT
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__attribute__ ((__pure__));
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};
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_GLIBCXX_EH_PTR_USED
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_GLIBCXX26_CONSTEXPR inline
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exception_ptr::exception_ptr() _GLIBCXX_USE_NOEXCEPT
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: _M_exception_object(0)
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{ }
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_GLIBCXX_EH_PTR_USED
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_GLIBCXX26_CONSTEXPR inline
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exception_ptr::exception_ptr(const exception_ptr& __other)
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_GLIBCXX_USE_NOEXCEPT
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: _M_exception_object(__other._M_exception_object)
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{
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if (_M_exception_object)
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{
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#if __cpp_if_consteval >= 202106L \
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&& _GLIBCXX_HAS_BUILTIN(__builtin_eh_ptr_adjust_ref)
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if consteval {
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__builtin_eh_ptr_adjust_ref(_M_exception_object, 1);
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return;
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}
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#endif
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_M_addref();
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}
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}
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_GLIBCXX_EH_PTR_USED
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_GLIBCXX26_CONSTEXPR inline
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exception_ptr::~exception_ptr() _GLIBCXX_USE_NOEXCEPT
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{
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if (_M_exception_object)
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{
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#if __cpp_if_consteval >= 202106L \
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&& _GLIBCXX_HAS_BUILTIN(__builtin_eh_ptr_adjust_ref)
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if consteval {
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__builtin_eh_ptr_adjust_ref(_M_exception_object, -1);
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return;
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}
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#endif
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_M_release();
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}
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}
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_GLIBCXX_EH_PTR_USED
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_GLIBCXX26_CONSTEXPR inline exception_ptr&
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exception_ptr::operator=(const exception_ptr& __other) _GLIBCXX_USE_NOEXCEPT
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{
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exception_ptr(__other).swap(*this);
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return *this;
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}
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_GLIBCXX_EH_PTR_USED
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_GLIBCXX26_CONSTEXPR inline void
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exception_ptr::swap(exception_ptr &__other) _GLIBCXX_USE_NOEXCEPT
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{
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void *__tmp = _M_exception_object;
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_M_exception_object = __other._M_exception_object;
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__other._M_exception_object = __tmp;
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}
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/// @relates exception_ptr
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_GLIBCXX26_CONSTEXPR inline void
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swap(exception_ptr& __lhs, exception_ptr& __rhs)
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{ __lhs.swap(__rhs); }
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/// @cond undocumented
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template<typename _Ex>
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_GLIBCXX_CDTOR_CALLABI
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inline void
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__dest_thunk(void* __x)
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{ static_cast<_Ex*>(__x)->~_Ex(); }
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/// @endcond
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} // namespace __exception_ptr
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using __exception_ptr::swap; // So that std::swap(exp1, exp2) finds it.
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/// Obtain an exception_ptr pointing to a copy of the supplied object.
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template<typename _Ex>
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#if !(__cplusplus >= 201103L && __cpp_rtti) && !__cpp_exceptions
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// This is always_inline so the linker will never use a useless definition
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// instead of a working one compiled with RTTI and/or exceptions enabled.
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__attribute__ ((__always_inline__)) inline
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#endif
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_GLIBCXX26_CONSTEXPR exception_ptr
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make_exception_ptr(_Ex __ex) _GLIBCXX_USE_NOEXCEPT
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{
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#if __cplusplus >= 201103L && __cpp_rtti
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// For runtime calls with -frtti enabled we can avoid try-catch overhead.
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// We can't use this for C++98 because it relies on std::decay.
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#ifdef __glibcxx_constexpr_exceptions
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if ! consteval
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#endif
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{
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using _Ex2 = typename decay<_Ex>::type;
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void* __e = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ex));
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(void) __cxxabiv1::__cxa_init_primary_exception(
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__e, const_cast<std::type_info*>(&typeid(_Ex)),
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__exception_ptr::__dest_thunk<_Ex2>);
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__try
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{
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::new (__e) _Ex2(__ex);
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return exception_ptr(__e);
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}
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__catch(...)
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{
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__cxxabiv1::__cxa_free_exception(__e);
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return current_exception();
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}
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}
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#endif
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#ifdef __cpp_exceptions
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try
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{
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throw __ex;
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}
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catch(...)
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{
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return current_exception();
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}
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#endif
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return exception_ptr();
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}
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#if __cpp_lib_exception_ptr_cast >= 202506L
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template<typename _Ex>
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[[__gnu__::__always_inline__]]
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constexpr const _Ex*
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exception_ptr_cast(const exception_ptr& __p) noexcept
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{
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static_assert(!std::is_const_v<_Ex>);
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static_assert(!std::is_reference_v<_Ex>);
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static_assert(std::is_object_v<_Ex>);
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static_assert(!std::is_array_v<_Ex>);
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static_assert(!std::is_pointer_v<_Ex>);
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static_assert(!std::is_member_pointer_v<_Ex>);
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#ifdef __cpp_rtti
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// For runtime calls with -frtti enabled we can avoid try-catch overhead.
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if ! consteval {
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const type_info &__id = typeid(const _Ex&);
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return static_cast<const _Ex*>(__p._M_exception_ptr_cast(__id));
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}
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#endif
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#ifdef __cpp_exceptions
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if (__p._M_exception_object)
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try
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{
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std::rethrow_exception(__p);
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}
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catch (const _Ex& __exc)
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{
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return &__exc;
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}
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catch (...)
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{
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}
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#endif
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return nullptr;
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}
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#endif
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#undef _GLIBCXX_EH_PTR_USED
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/// @} group exceptions
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} // namespace std
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} // extern "C++"
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#endif
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