/*
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* Copyright Andrey Semashev 2018 - 2020.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* https://www.boost.org/LICENSE_1_0.txt)
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*/
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/*!
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* \file uncaught_exceptions.hpp
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* \author Andrey Semashev
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* \date 2018-11-10
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*
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* \brief This header provides an `uncaught_exceptions` function implementation, which was introduced in C++17.
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*
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* The code in this file is based on the implementation by Evgeny Panasyuk:
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*
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* https://github.com/panaseleus/stack_unwinding/blob/master/boost/exception/uncaught_exception_count.hpp
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*/
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#ifndef BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
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#define BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
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#include <exception>
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#include <boost/config.hpp>
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#if defined(BOOST_HAS_PRAGMA_ONCE)
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#pragma once
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#endif
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#if defined(__APPLE__)
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#include <Availability.h>
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// Apple systems only support std::uncaught_exceptions starting with specific versions:
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// - Mac OS >= 10.12
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// - iOS >= 10.0
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// - tvOS >= 10.0
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// - watchOS >= 3.0
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// https://github.com/boostorg/core/issues/80
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#if (defined(__cpp_lib_uncaught_exceptions) && __cpp_lib_uncaught_exceptions >= 201411) && \
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( \
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(defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 101200) || \
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(defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED >= 100000) \
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)
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#define BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
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#endif
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// Visual Studio 14.0 supports N4152 std::uncaught_exceptions() but doesn't define __cpp_lib_uncaught_exceptions
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#elif (defined(__cpp_lib_uncaught_exceptions) && __cpp_lib_uncaught_exceptions >= 201411) || \
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(defined(_MSC_VER) && _MSC_VER >= 1900)
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#define BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
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#endif
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#if !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
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// cxxabi.h availability macro
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#if defined(__has_include) && (!defined(BOOST_GCC) || (__GNUC__ >= 5))
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# if __has_include(<cxxabi.h>)
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# define BOOST_CORE_HAS_CXXABI_H
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# endif
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#elif defined(__GLIBCXX__) || defined(__GLIBCPP__)
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# define BOOST_CORE_HAS_CXXABI_H
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#endif
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#if defined(BOOST_CORE_HAS_CXXABI_H)
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// MinGW GCC 4.4 seem to not work the same way the newer GCC versions do. As a result, __cxa_get_globals based implementation will always return 0.
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// Just disable it for now and fall back to std::uncaught_exception().
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// On AIX, xlclang++ does have cxxabi.h but doesn't have __cxa_get_globals (https://github.com/boostorg/core/issues/78).
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#if !( \
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(defined(__MINGW32__) && (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) < 405)) || \
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defined(__ibmxl__) \
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)
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#include <cxxabi.h>
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#include <cstring>
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#define BOOST_CORE_HAS_CXA_GET_GLOBALS
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// At least on MinGW and Linux, only GCC since 4.7 declares __cxa_get_globals() in cxxabi.h. Older versions of GCC do not expose this function but it's there.
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// On OpenBSD, it seems, the declaration is also missing.
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// Note that at least on FreeBSD 11, cxxabi.h declares __cxa_get_globals with a different exception specification, so we can't declare the function unconditionally.
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// On Linux with clang and libc++ and on OS X, there is a version of cxxabi.h from libc++abi that doesn't declare __cxa_get_globals, but provides __cxa_uncaught_exceptions.
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// The function only appeared in version _LIBCPPABI_VERSION >= 1002 of the library. Unfortunately, there are linking errors about undefined reference to __cxa_uncaught_exceptions
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// on Ubuntu Trusty and OS X, so we avoid using it and forward-declare __cxa_get_globals instead.
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// On QNX SDP 7.0 (QCC 5.4.0), there are multiple cxxabi.h, one from glibcxx from gcc and another from libc++abi from LLVM. Which one is included will be determined by the qcc
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// command line arguments (-V and/or -Y; http://www.qnx.com/developers/docs/7.0.0/#com.qnx.doc.neutrino.utilities/topic/q/qcc.html). The LLVM libc++abi is missing the declaration
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// of __cxa_get_globals but it is also patched by QNX developers to not define _LIBCPPABI_VERSION. Older QNX SDP versions, up to and including 6.6, don't provide LLVM and libc++abi.
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// See https://github.com/boostorg/core/issues/59.
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#if !defined(__FreeBSD__) && \
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( \
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(defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) < 407) || \
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defined(__OpenBSD__) || \
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(defined(__QNXNTO__) && !defined(__GLIBCXX__) && !defined(__GLIBCPP__)) || \
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defined(_LIBCPPABI_VERSION) \
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)
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namespace __cxxabiv1 {
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struct __cxa_eh_globals;
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#if defined(__OpenBSD__)
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extern "C" __cxa_eh_globals* __cxa_get_globals();
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#else
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extern "C" __cxa_eh_globals* __cxa_get_globals() BOOST_NOEXCEPT_OR_NOTHROW __attribute__((__const__));
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#endif
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} // namespace __cxxabiv1
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#endif
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#endif
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#endif // defined(BOOST_CORE_HAS_CXXABI_H)
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#if defined(_MSC_VER) && _MSC_VER >= 1400
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#include <cstring>
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#define BOOST_CORE_HAS_GETPTD
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namespace boost {
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namespace core {
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namespace detail {
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extern "C" void* _getptd();
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} // namespace detail
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} // namespace core
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} // namespace boost
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#endif // defined(_MSC_VER) && _MSC_VER >= 1400
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#endif // !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
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#if !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS) && !defined(BOOST_CORE_HAS_CXA_GET_GLOBALS) && !defined(BOOST_CORE_HAS_GETPTD)
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//! This macro is defined when `uncaught_exceptions` is not guaranteed to return values greater than 1 if multiple exceptions are pending
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#define BOOST_CORE_UNCAUGHT_EXCEPTIONS_EMULATED
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#endif
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namespace boost {
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namespace core {
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//! Returns the number of currently pending exceptions
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inline unsigned int uncaught_exceptions() BOOST_NOEXCEPT
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{
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#if defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
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// C++17 implementation
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return static_cast< unsigned int >(std::uncaught_exceptions());
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#elif defined(BOOST_CORE_HAS_CXA_GET_GLOBALS)
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// Tested on {clang 3.2,GCC 3.5.6,GCC 4.1.2,GCC 4.4.6,GCC 4.4.7}x{x32,x64}
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unsigned int count;
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std::memcpy(&count, reinterpret_cast< const unsigned char* >(::abi::__cxa_get_globals()) + sizeof(void*), sizeof(count)); // __cxa_eh_globals::uncaughtExceptions, x32 offset - 0x4, x64 - 0x8
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return count;
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#elif defined(BOOST_CORE_HAS_GETPTD)
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// MSVC specific. Tested on {MSVC2005SP1,MSVC2008SP1,MSVC2010SP1,MSVC2012}x{x32,x64}.
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unsigned int count;
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std::memcpy(&count, static_cast< const unsigned char* >(boost::core::detail::_getptd()) + (sizeof(void*) == 8u ? 0x100 : 0x90), sizeof(count)); // _tiddata::_ProcessingThrow, x32 offset - 0x90, x64 - 0x100
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return count;
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#else
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// Portable C++03 implementation. Does not allow to detect multiple nested exceptions.
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return static_cast< unsigned int >(std::uncaught_exception());
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#endif
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}
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} // namespace core
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} // namespace boost
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#undef BOOST_CORE_HAS_CXXABI_H
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#undef BOOST_CORE_HAS_CXA_GET_GLOBALS
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#undef BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
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#undef BOOST_CORE_HAS_GETPTD
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#endif // BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
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