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40 lines
1.1 KiB
Rust
40 lines
1.1 KiB
Rust
// Regression test for #20831: debruijn index account was thrown off
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// by the (anonymous) lifetime in `<Self as Publisher>::Output`
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// below. Note that changing to a named lifetime made the problem go
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// away.
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use std::cell::RefCell;
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use std::ops::{Shl, Shr};
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pub trait Subscriber {
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type Input;
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}
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pub trait Publisher<'a> {
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type Output;
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fn subscribe(&mut self, _: Box<dyn Subscriber<Input=Self::Output> + 'a>);
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}
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pub trait Processor<'a> : Subscriber + Publisher<'a> { }
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impl<'a, P> Processor<'a> for P where P : Subscriber + Publisher<'a> { }
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struct MyStruct<'a> {
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sub: Box<dyn Subscriber<Input=u64> + 'a>
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}
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impl<'a> Publisher<'a> for MyStruct<'a> {
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type Output = u64;
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fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
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// Not obvious, but there is an implicit lifetime here -------^
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//~^^ ERROR cannot infer
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//
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// The fact that `Publisher` is using an implicit lifetime is
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// what was causing the debruijn accounting to be off, so
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// leave it that way!
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self.sub = t;
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}
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}
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fn main() {}
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