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//@ build-pass
//@ edition:2021
//@ compile-flags: -Cdebuginfo=2
// We were not normalizing opaques with escaping bound vars during codegen,
// leading to later errors during debuginfo computation.
#[derive(Clone, Copy)]
pub struct SharedState {}
pub trait State {
#[allow(async_fn_in_trait)]
async fn execute(self, shared_state: &SharedState);
}
pub trait StateComposer {
fn and_then<T, F>(self, map_fn: F) -> AndThen<Self, F>
where
Self: State + Sized,
T: State,
F: FnOnce() -> T,
{
AndThen { previous: self, map_fn }
}
}
impl<T> StateComposer for T where T: State {}
pub struct AndThen<T, F> {
previous: T,
map_fn: F,
}
impl<T, U, F> State for AndThen<T, F>
where
T: State,
U: State,
F: FnOnce() -> U,
{
async fn execute(self, shared_state: &SharedState)
where
Self: Sized,
{
self.previous.execute(shared_state).await;
(self.map_fn)().execute(shared_state).await
}
}
pub struct SomeState {}
impl State for SomeState {
async fn execute(self, shared_state: &SharedState) {}
}
pub fn main() {
let shared_state = SharedState {};
async {
SomeState {}
.and_then(|| SomeState {})
.and_then(|| SomeState {})
.execute(&shared_state)
.await;
};
}
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