66 lines
1.3 KiB
Rust
66 lines
1.3 KiB
Rust
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// edition:2021
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// check-pass
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#![feature(type_alias_impl_trait)]
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#![feature(closure_lifetime_binder)]
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use std::future::Future;
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trait AsyncFn<I, R>: FnMut(I) -> Self::Fut {
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type Fut: Future<Output = R>;
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}
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impl<F, I, R, Fut> AsyncFn<I, R> for F
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where
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Fut: Future<Output = R>,
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F: FnMut(I) -> Fut,
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{
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type Fut = Fut;
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}
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async fn call<C, R, F>(mut ctx: C, mut f: F) -> Result<R, ()>
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where
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F: for<'a> AsyncFn<&'a mut C, Result<R, ()>>,
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{
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loop {
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match f(&mut ctx).await {
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Ok(val) => return Ok(val),
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Err(_) => continue,
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}
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}
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}
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trait Cap<'a> {}
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impl<T> Cap<'_> for T {}
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fn works(ctx: &mut usize) {
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let mut inner = 0;
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type Ret<'a, 'b: 'a> = impl Future<Output = Result<usize, ()>> + 'a + Cap<'b>;
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let callback = for<'a, 'b> |c: &'a mut &'b mut usize| -> Ret<'a, 'b> {
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inner += 1;
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async move {
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let _c = c;
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Ok(1usize)
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}
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};
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call(ctx, callback);
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}
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fn doesnt_work_but_should(ctx: &mut usize) {
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let mut inner = 0;
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type Ret<'a, 'b: 'a> = impl Future<Output = Result<usize, ()>> + 'a + Cap<'b>;
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call(ctx, for<'a, 'b> |c: &'a mut &'b mut usize| -> Ret<'a, 'b> {
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inner += 1;
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async move {
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let _c = c;
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Ok(1usize)
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}
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});
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}
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fn main() {}
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