c++ - C++20 in g++10: generator not defined

Question

This MCVE works fine in Visual Studio.

#include <experimental/generator>
#include <iostream>

std::experimental::generator<int> f() { for (int i = 0; i < 10; ++i) co_yield i; }

int main ()
{
    for (int i : f())
        std::cout << i << ' ';

    return 0;
}

but in g++10, which is listed as having full support or C++20's coroutines, it does not.

(Taking out experimental doesn't help.)

I am compiling thus: g++ -g -std=c++2a -fcoroutines -c main.cpp.

It complains that there is no include file generator, and if I take out the #include, that generator is not a part of std:: or is not defined. I suppose there's another name for it in the new standard? Or if not, what do I do instead to get a coroutine that uses co_yield?

Answer 1

Nothing in GCC's status list alongside its coroutine support says it supports anything other than p0912r5, which does not provide std::generator, experimentally or otherwise.

I recall that VS added <experimental/generator> a few years ago; I guess GCC never did.

If it's currently proposed for inclusion in C++, and you can find the relevant proposal, perhaps you can track its support status. But honestly, for now, you'd be better off writing your own that works until it becomes part of some actual standard.

tl;dr: Though it is a coroutine, this feature is not part of the Coroutines TS.