reinterpret_cast std::function* 往返于 void* [英] reinterpret_cast std::function* to and from void*

问题描述

当我调用从主可执行文件传递的 std::function 时，我在插件中遇到了段错误，方法是将其地址转换为 void*.我可以用几行独立的代码重现这个问题:

I'm suffering a segfault in a plugin when I call a std::function in it passed from the main executable, via converting it's address to/from void*. I can reproduce the problem in a few self-contained lines:

#include <iostream>
#include <functional>

int main()
{
    using func_t = std::function<const std::string& ()>;

    auto hn_getter = func_t{[]() {
        return "Hello";
    }};

    auto ptr = reinterpret_cast<void*>(&hn_getter);

    auto getter = reinterpret_cast<func_t*>(ptr);
    std::cout << (*getter)() << std::endl;   // Bang!

    return EXIT_SUCCESS;
}

即使我正在转换为原始类型，它仍然存在段错误.谁能看出我哪里出错了?

Even though I'm casting to the original type, it's still segfaulting. Can anyone see where I'm going wrong?

推荐答案

你的问题的原因与 cast 无关，是因为函数返回了一个 const string &.您需要:

The cause of your problem has nothing to do with cast, it's because of the function return a const string &. You need:

using func_t = std::function<const std::string ()>;

正如评论所暗示的，const 这里没有用，只是:

And as comments suggest, const here is useless, just:

using func_t = std::function<std::string ()>;

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