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