warning: unused closure that must be used
  --> $DIR/issue-1460.rs:6:5
   |
LL |     {|i: u32| if 1 == i { }};
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_must_use)]` on by default
   = note: closures are lazy and do nothing unless called

warning: 1 warning emitted