error[E0308]: mismatched types --> $DIR/hang-on-deeply-nested-dyn.rs:12:5 | LL | ) -> &dyn Fn( | ______- LL | | &dyn Fn( LL | | &dyn Fn( LL | | &dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(&dyn Fn(u32))))))))), LL | | ), LL | | ), LL | | ) { | |_- expected `&dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn Fn(u32) + 'a)) + 'a)) + 'a)) + 'a)) + 'a)) + 'a)) + 'a)) + 'a)) + 'a)) + 'a)) + 'a))` because of return type LL | f | ^ expected reference, found `u32` | = note: expected reference `&dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a (dyn for<'a> Fn(&'a ...) + 'a)) + 'a)) + 'a))` the full type name has been written to '$TEST_BUILD_DIR/higher-rank-trait-bounds/hang-on-deeply-nested-dyn/hang-on-deeply-nested-dyn.long-type-hash.txt' found reference `&dyn Fn(u32)` error: aborting due to previous error For more information about this error, try `rustc --explain E0308`.