src/test/run-pass/generator/nested_generators.rs

// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// run-pass

#![feature(generators)]
#![feature(generator_trait)]

use std::ops::Generator;
use std::ops::GeneratorState;

fn main() {
    let _generator = || {
        let mut sub_generator = || {
            yield 2;
        };

        match unsafe { sub_generator.resume() } {
            GeneratorState::Yielded(x) => {
                yield x;
            }
            _ => panic!(),
        };
    };
}