mirror of https://github.com/rust-lang/rust
34 lines
504 B
Rust
34 lines
504 B
Rust
//@ edition:2018
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//@ run-pass
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use std::future::Future;
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trait AsyncCallback<'a> {
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type Out;
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}
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impl<'a, Fut, T, F> AsyncCallback<'a> for F
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where
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F: FnOnce(&'a mut ()) -> Fut,
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Fut: Future<Output = T> + Send + 'a,
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{
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type Out = T;
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}
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trait CallbackMarker {}
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impl<F, T> CallbackMarker for F
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where
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T: 'static,
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for<'a> F: AsyncCallback<'a, Out = T> + Send,
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{
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}
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fn do_sth<F: CallbackMarker>(_: F) {}
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async fn callback(_: &mut ()) -> impl Send {}
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fn main() {
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do_sth(callback);
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}
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