rust/tests/ui/error-codes/E0746.stderr

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/E0746.rs:8:13
   |
LL | fn foo() -> dyn Trait { Struct }
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
help: consider returning an `impl Trait` instead of a `dyn Trait`
   |
LL | fn foo() -> impl Trait { Struct }
   |             ~~~~
help: alternatively, box the return type, and wrap all of the returned values in `Box::new`
   |
LL | fn foo() -> Box<dyn Trait> { Box::new(Struct) }
   |             ++++         +   +++++++++      +

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/E0746.rs:11:13
   |
LL | fn bar() -> dyn Trait {
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
   = help: if there were a single returned type, you could use `impl Trait` instead
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL ~ fn bar() -> Box<dyn Trait> {
LL |     if true {
LL ~         return Box::new(0);
LL |     }
LL ~     Box::new(42)
   |

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0746`.