//@ check-pass pub trait Foo<'a> { type Bar; fn foo(&'a self) -> Self::Bar; } impl<'a, 'b, T: 'a> Foo<'a> for &'b T { type Bar = &'a T; fn foo(&'a self) -> &'a T { self } } pub fn uncallable(x: T, f: F) where T: for<'a> Foo<'a>, F: for<'a> Fn(>::Bar), { f(x.foo()); } pub fn catalyst(x: &i32) { broken(x, |_| {}) } pub fn broken(x: &i32, f: F) { uncallable(x, |y| f(y)); } fn main() {}