//! This test ensures that a mutable reference cannot be passed as a resume argument twice. #![feature(generators, generator_trait)] use std::marker::Unpin; use std::ops::{ Generator, GeneratorState::{self, *}, }; use std::pin::Pin; fn main() { let mut thing = String::from("hello"); let mut gen = |r| { if false { yield r; } }; let mut gen = Pin::new(&mut gen); gen.as_mut().resume(&mut thing); gen.as_mut().resume(&mut thing); //~^ cannot borrow `thing` as mutable more than once at a time }