在C ++中使用<execution>标头的问题

我在Windows 10上安装了gcc 10.2.0，因此已在最新版本的gcc中实现。
问题是，当我从以下链接复制示例代码时：https : //docs.w3cub.com/cpp/algorithm/reduce，它说：std :: execution尚未声明。任何的想法？

#include <iostream>
#include <chrono>
#include <vector>
#include <numeric>
#include <execution>
 
int main()
{
    std::vector<double> v(10'000'007, 0.5);
 
    {
        auto t1 = std::chrono::high_resolution_clock::now();
        double result = std::accumulate(v.begin(), v.end(), 0.0);
        auto t2 = std::chrono::high_resolution_clock::now();
        std::chrono::duration<double, std::milli> ms = t2 - t1;
        std::cout << std::fixed << "std::accumulate result " << result
                  << " took " << ms.count() << " ms\n";
    }
 
    {
        auto t1 = std::chrono::high_resolution_clock::now();
        double result = std::reduce(std::execution::par, v.begin(), v.end());
        auto t2 = std::chrono::high_resolution_clock::now();
        std::chrono::duration<double, std::milli> ms = t2 - t1;
        std::cout << "std::reduce result "
                  << result << " took " << ms.count() << " ms\n";
    }
}