_GLIBCXX_USE_CXX11_ABI在RHEL6和RHEL7上被禁用了吗? [英] _GLIBCXX_USE_CXX11_ABI disabled on RHEL6 and RHEL7?

问题描述

我在RHEL6和RHEL7上有gcc 5.2.1，看起来_GLIBCXX_USE_CXX11_ABI被禁用了.即使我手动运行-D_GLIBCXX_USE_CXX11_ABI=1 -std=c++14，它也不起作用.这意味着我不会获得小的字符串优化功能.例如，以下代码的输出始终为8和未设置微".对于SSO，如果我们查看代码bit/basic_string.h，则std :: string的大小应至少为16.有什么解决方法吗?

I have gcc 5.2.1 on RHEL6 and RHEL7, and it looks like _GLIBCXX_USE_CXX11_ABI gets disabled. It's not working even if I manually run -D_GLIBCXX_USE_CXX11_ABI=1 -std=c++14. This means I won't get small string optimization feature. For example, the output of following code always have 8 and 'micro not set'. For SSO, size of std::string should be at least 16 if we look at code bits/basic_string.h. Any workaround?

#include <string>
#include <iostream>

int main()
{
    std::cout << sizeof(std::string) << std::endl;

#if _GLIBCXX_USE_CXX11_ABI
    std::cout << "macro set" << std::endl;
#else
    std::cout << "macro not set" << std::endl;
#endif

}

推荐答案

Jakub Jelinek 2018-02-19 06:08:00 EST

Jakub Jelinek 2018-02-19 06:08:00 EST

我们已经尽力了，但是不可能支持这一点，无论是在 RHEL6或RHEL7上也没有，这就是为什么它被强制禁用.它会 在RHEL8中工作(也是默认设置).

We've tried hard, but it is not possible to support this, neither on RHEL6 nor on RHEL7, which is why it is forcefully disabled. It will work in RHEL8 (and be the default there as well).

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