// check-pass #![feature(unboxed_closures)] fn is_fn<T: for<'a> Fn<(&'a (),)>>() {} fn is_fn2<T: for<'a, 'b> Fn<(&'a &'b (),)>>() {} struct Outlives<'a, 'b>(std::marker::PhantomData<&'a &'b ()>); fn main() { is_fn::<for<'a> fn(&'a ()) -> &'a ()>(); is_fn::<for<'a> fn(&'a ()) -> &'a dyn std::fmt::Debug>(); is_fn2::<for<'a, 'b> fn(&'a &'b ()) -> Outlives<'a, 'b>>(); is_fn2::<for<'a, 'b> fn(&'a &'b ()) -> (&'a (), &'a ())>(); }