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|
#![feature(generators, generator_trait)]
use std::{
cell::RefCell,
sync::Arc,
pin::Pin,
ops::{Generator, GeneratorState},
};
pub struct Ready<T>(Option<T>);
impl<T> Generator<()> for Ready<T> {
type Return = T;
type Yield = ();
fn resume(mut self: Pin<&mut Self>, _args: ()) -> GeneratorState<(), T> {
GeneratorState::Complete(self.0.take().unwrap())
}
}
pub fn make_gen1<T>(t: T) -> Ready<T> {
Ready(Some(t))
}
fn require_send(_: impl Send) {}
//~^ NOTE required by a bound
//~| NOTE required by a bound
//~| NOTE required by this bound
//~| NOTE required by this bound
fn make_non_send_generator() -> impl Generator<Return = Arc<RefCell<i32>>> {
make_gen1(Arc::new(RefCell::new(0)))
}
fn test1() {
let send_gen = || {
let _non_send_gen = make_non_send_generator();
//~^ NOTE not `Send`
yield;
//~^ NOTE yield occurs here
//~| NOTE value is used across a yield
}; //~ NOTE later dropped here
require_send(send_gen);
//~^ ERROR generator cannot be sent between threads
//~| NOTE not `Send`
}
pub fn make_gen2<T>(t: T) -> impl Generator<Return = T> {
//~^ NOTE appears within the type
//~| NOTE expansion of desugaring
|| { //~ NOTE used within this generator
yield;
t
}
}
fn make_non_send_generator2() -> impl Generator<Return = Arc<RefCell<i32>>> { //~ NOTE appears within the type
//~^ NOTE expansion of desugaring
make_gen2(Arc::new(RefCell::new(0)))
}
fn test2() {
let send_gen = || { //~ NOTE used within this generator
let _non_send_gen = make_non_send_generator2();
yield;
};
require_send(send_gen);
//~^ ERROR `RefCell<i32>` cannot be shared between threads safely
//~| NOTE `RefCell<i32>` cannot be shared between threads safely
//~| NOTE required for
//~| NOTE required by a bound introduced by this call
//~| NOTE captures the following types
}
fn main() {}
|
