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//@ build-fail
//@ aux-build:block-on.rs
//@ edition:2021
// Regression test for <https://github.com/rust-lang/rust/issues/135780>.
extern crate block_on;
use std::future::Future;
use std::ops::AsyncFnMut;
use std::pin::{Pin, pin};
use std::task::*;
trait Db {}
impl Db for () {}
struct Env<'db> {
db: &'db (),
}
#[derive(Debug)]
enum SymPerm<'db> {
Dummy(&'db ()),
Apply(Box<SymPerm<'db>>, Box<SymPerm<'db>>),
}
pub struct ToChain<'env, 'db> {
db: &'db dyn crate::Db,
env: &'env Env<'db>,
}
impl<'env, 'db> ToChain<'env, 'db> {
fn perm_pairs<'l>(
&'l self,
perm: &'l SymPerm<'db>,
yield_chain: &'l mut impl AsyncFnMut(&SymPerm<'db>),
) -> Pin<Box<dyn std::future::Future<Output = ()> + 'l>> {
Box::pin(async move {
match perm {
SymPerm::Dummy(_) => yield_chain(perm).await,
SymPerm::Apply(l, r) => {
self.perm_pairs(l, &mut async move |left_pair| {
//~^ ERROR reached the recursion limit while instantiating
self.perm_pairs(r, yield_chain).await
})
.await
}
}
})
}
}
fn main() {
block_on::block_on(async {
let pair = SymPerm::Apply(Box::new(SymPerm::Dummy(&())), Box::new(SymPerm::Dummy(&())));
ToChain { db: &(), env: &Env { db: &() } }
.perm_pairs(&pair, &mut async |p| {
eprintln!("{p:?}");
})
.await;
});
}
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