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// edition:2021
// [next] compile-flags: -Zlower-impl-trait-in-trait-to-assoc-ty
// revisions: current next
#![feature(return_position_impl_trait_in_trait)]
#![allow(incomplete_features)]
use std::future::Future;
trait Captures<'a> {}
impl<T> Captures<'_> for T {}
trait Captures2<'a, 'b> {}
impl<T> Captures2<'_, '_> for T {}
pub trait AsyncTrait {
fn async_fn(&self, buff: &[u8]) -> impl Future<Output = Vec<u8>>;
fn async_fn_early<'a: 'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>>;
fn async_fn_multiple<'a>(&'a self, buff: &[u8])
-> impl Future<Output = Vec<u8>> + Captures<'a>;
fn async_fn_reduce_outlive<'a, T>(
&'a self,
buff: &[u8],
t: T,
) -> impl Future<Output = Vec<u8>> + 'a;
fn async_fn_reduce<'a, T>(
&'a self,
buff: &[u8],
t: T,
) -> impl Future<Output = Vec<u8>> + Captures<'a>;
}
pub struct Struct;
impl AsyncTrait for Struct {
fn async_fn<'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>> + 'a {
//~^ ERROR return type captures more lifetimes than trait definition
async move { buff.to_vec() }
}
fn async_fn_early<'a: 'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>> + 'a {
//~^ ERROR return type captures more lifetimes than trait definition
async move { buff.to_vec() }
}
fn async_fn_multiple<'a, 'b>(
&'a self,
buff: &'b [u8],
) -> impl Future<Output = Vec<u8>> + Captures2<'a, 'b> {
//~^ ERROR return type captures more lifetimes than trait definition
async move { buff.to_vec() }
}
fn async_fn_reduce_outlive<'a, 'b, T>(
&'a self,
buff: &'b [u8],
t: T,
) -> impl Future<Output = Vec<u8>> {
//~^ ERROR the parameter type `T` may not live long enough
async move {
let _t = t;
vec![]
}
}
// OK: We remove the `Captures<'a>`, providing a guarantee that we don't capture `'a`,
// but we still fulfill the `Captures<'a>` trait bound.
fn async_fn_reduce<'a, 'b, T>(&'a self, buff: &'b [u8], t: T) -> impl Future<Output = Vec<u8>> {
async move {
let _t = t;
vec![]
}
}
}
fn main() {}
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