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//@ check-pass
// Related to Bevy regression #115559, found in
// a crater run on #118553.
pub trait QueryBase {
type Db;
}
pub trait AsyncQueryFunction<'f>: // 'f is important
QueryBase<Db = <Self as AsyncQueryFunction<'f>>::SendDb> // bound is important
{
type SendDb;
}
pub struct QueryTable<'me, Q, DB> {
_q: Option<Q>,
_db: Option<DB>,
_marker: Option<&'me ()>,
}
impl<'me, Q> QueryTable<'me, Q, <Q as QueryBase>::Db>
where
Q: for<'f> AsyncQueryFunction<'f>,
{
// When borrowchechking this function we normalize `<Q as QueryBase>::Db` in the
// function signature to `<Self as QueryFunction<'?x>>::SendDb`, where `'?x` is an
// unconstrained region variable. We then addd `<Self as QueryFunction<'?x>>::SendDb: 'a`
// as an implied bound. We currently a structural equality to decide whether this bound
// should be used to prove the bound `<Self as QueryFunction<'?x>>::SendDb: 'a`. For this
// to work we may have to structurally resolve regions as the actually used vars may
// otherwise be semantically equal but structurally different.
pub fn get_async<'a>(&'a mut self) {
panic!();
}
}
fn main() {}
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