Seemingly infinite loop in translation item collection #34416
Comments
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Ok, managed to reduce it to this: pub trait Future: 'static {
type Item;
type Error;
fn boxed(self) -> Box<Future<Item=Self::Item, Error=Self::Error>>
where Self: Sized
{
Box::new(self)
}
fn map(self) -> Map<Self>
where Self: Sized,
{
loop {}
}
fn forget(self) where Self: Sized {
self.map().boxed();
}
}
// =============================================================================
pub struct Map<A> {
_future: A,
}
impl<A> Future for Map<A>
where A: Future,
{
type Item = ();
type Error = A::Error;
}
// =============================================================================
pub struct Promise;
impl Future for Promise {
type Item = ();
type Error = ();
}
// =============================================================================
fn foo() -> Promise {
loop {}
}
fn main() {
foo().boxed();
}If This is in theory just a reduced down version of the original crate, so presumably it was just going to take a very long time to say that before? Haven't quite figured out how this program is causing the recursion limit to get hit... |
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@eddyb managed to reduce further: pub trait Future: 'static {
fn forget(self) where Self: Sized {
Box::new(Map(self)) as Box<Future>;
}
}
pub struct Map<A>(A);
impl<A: Future> Future for Map<A> {}
pub struct Promise;
impl Future for Promise {}
fn main() {
Promise.forget();
} |
bors
added a commit
that referenced
this issue
Jun 27, 2016
Don't translate vtable methods with Self: Sized bounds. Fixes #34416.
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When compiling this file with
cargo build --test eventualin that repository (at that revision), the compiler seemingly hangs. The stack trace after awhile is:And the logs towards the end look like this: https://gist.github.com/alexcrichton/08e46aaef1c170e74752ce1d75287a02
cc @michaelwoerister, looks to be hanging during translation item collections
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