小编Ger*_*097的帖子

我试图从文档页面https://en.cppreference.com/w/cpp/thread/call_once运行示例，但它没有按预期工作。它会无限卡住。我想知道为什么会发生这种情况，或者它是否只是与某些特定编译器版本相关的错误。这是我用来运行程序https://repl.it/repls/UtterJubilantArchitects

#include <iostream>
#include <thread>
#include <mutex>

std::once_flag flag1, flag2;

void simple_do_once()
{
    std::call_once(flag1, [](){ std::cout << "Simple example: called once\n"; });
}

void may_throw_function(bool do_throw)
{
  if (do_throw) {
    std::cout << "throw: call_once will retry\n"; // this may appear more than once
    throw std::exception();
  }
  std::cout << "Didn't throw, call_once will not attempt again\n"; // guaranteed once
}

void do_once(bool do_throw)
{
  try {
    std::call_once(flag2, may_throw_function, do_throw);
  }
  catch (...) {
  }
}

int main()
{ …