升级到C ++ 17-错误：'__BEGIN_NAMESPACE_STD'没有命名类型

Question

我正在尝试将应用程序升级到C ++ 17并收到以下编译器错误：

error: ‘__BEGIN_NAMESPACE_STD’ does not name a type

我正在使用gcc（GCC）8.2.0并使用以下命令进行编译：

g++ -std=c++17 variant.cpp -o variant

这是一个小测试程序：

#include <iostream>
#include <variant>

using v_t = std::variant<int, double>;

int main(int argc, char const* argv[]) {

    v_t foo = 5;
    printf("foo contains %d\n", *std::get_if<int>(&foo));

    std::cout << "Success" << std::endl;
    return 0;
}

这是我得到的错误（如下）。请注意，如何在stdlib.h中启用__BEGIN_NAMESPACE_STD讨论了类似的问题，但是建议的解决方案（包括C ++头文件，而不是诸如stdlib.h之类的C头文件）是我已经在做的事情。

我能够在OSX便携式计算机上编译此代码，可能是因为默认情况下安装了更新的libc。但是，当我在Linux机器上运行时，出现这些错误。在Linux机器上，我正在使用以下链接器/ glibc版本：ldd (Ubuntu EGLIBC 2.19-0ubuntu6.14) 2.19

我正在继续调试，但是希望有朝正确方向发展的指针。

In file included from /toolchains/gcc-8.2.0/include/c++/8.2.0/cstdlib:75,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/ext/string_conversions.h:41,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/bits/basic_string.h:6391,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/string:52,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/bits/locale_classes.h:40,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/bits/ios_base.h:41,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/ios:42,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/ostream:38,
                 from /toolchains/gcc-8.2.0/include/c++/8.2.0/iostream:39,
                 from variant.cpp:1:
/usr/include/stdlib.h:95:1: error: ‘__BEGIN_NAMESPACE_STD’ does not name a type
 __BEGIN_NAMESPACE_STD
 ^~~~~~~~~~~~~~~~~~~~~
/usr/include/stdlib.h:101:5: error: ‘div_t’ does not name a type; did you mean ‘pid_t’?
   } div_t;
     ^~~~~
     pid_t
/usr/include/stdlib.h:112:1: error: ‘__END_NAMESPACE_STD’ does not name a type
 __END_NAMESPACE_STD
 ^~~~~~~~~~~~~~~~~~~
/usr/include/stdlib.h:121:5: error: ‘lldiv_t’ does not name a type; did you mean ‘ldiv_t’?
   } lldiv_t;
     ^~~~~~~