// edition:2018 #![feature(async_closure)] use std::future::Future; // test the quality of annotations giving lifetimes names (`'1`) when async constructs are involved pub async fn async_fn(x: &mut i32) -> &i32 { let y = &*x; *x += 1; //~ ERROR cannot assign to `*x` because it is borrowed y } pub fn async_closure(x: &mut i32) -> impl Future<Output=&i32> { (async move || { let y = &*x; *x += 1; //~ ERROR cannot assign to `*x` because it is borrowed y })() } pub fn async_closure_explicit_return_type(x: &mut i32) -> impl Future<Output=&i32> { (async move || -> &i32 { let y = &*x; *x += 1; //~ ERROR cannot assign to `*x` because it is borrowed y })() } pub fn async_block(x: &mut i32) -> impl Future<Output=&i32> { async move { let y = &*x; *x += 1; //~ ERROR cannot assign to `*x` because it is borrowed y } } fn main() {}