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// This code (probably) _should_ compile, but it currently does not because we
// are not smart enough about implied bounds.
use std::io;
fn real_dispatch<T, F>(f: F) -> Result<(), io::Error>
//~^ NOTE required by a bound in this
where
F: FnOnce(&mut UIView<T>) -> Result<(), io::Error> + Send + 'static,
//~^ NOTE required by this bound in `real_dispatch`
//~| NOTE required by a bound in `real_dispatch`
{
todo!()
}
#[derive(Debug)]
struct UIView<'a, T: 'a> {
_phantom: std::marker::PhantomData<&'a mut T>,
}
trait Handle<'a, T: 'a, V, R> {
fn dispatch<F>(&self, f: F) -> Result<(), io::Error>
where
F: FnOnce(&mut V) -> R + Send + 'static;
}
#[derive(Debug, Clone)]
struct TUIHandle<T> {
_phantom: std::marker::PhantomData<T>,
}
impl<'a, T: 'a> Handle<'a, T, UIView<'a, T>, Result<(), io::Error>> for TUIHandle<T> {
fn dispatch<F>(&self, f: F) -> Result<(), io::Error>
where
F: FnOnce(&mut UIView<'a, T>) -> Result<(), io::Error> + Send + 'static,
{
real_dispatch(f)
//~^ ERROR expected a `FnOnce(&mut UIView<'_, T>)` closure, found `F`
//~| NOTE expected an `FnOnce(&mut UIView<'_, T>)` closure, found `F`
//~| NOTE expected a closure with arguments
//~| NOTE required by a bound introduced by this call
}
}
fn main() {}
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