| //@ revisions: old new | 
 | //@[old] edition:2015 | 
 | //@[new] edition:2021 | 
 | fn id<F>(f: Copy) -> usize { | 
 | //[new]~^ ERROR expected a type, found a trait | 
 | //[old]~^^ ERROR the trait `Copy` is not dyn compatible | 
 | //[old]~| ERROR the size for values of type `(dyn Copy + 'static)` | 
 | //[old]~| WARN trait objects without an explicit `dyn` are deprecated | 
 | //[old]~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021! | 
 | //[old]~| WARN trait objects without an explicit `dyn` are deprecated | 
 | //[old]~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021! | 
 |     f() | 
 |     //[old]~^ ERROR: expected function, found `(dyn Copy + 'static)` | 
 | } | 
 | fn main() {} |