error[E0308]: `if` and `else` have incompatible types
  --> $DIR/suggest-boxed-trait-objects-instead-of-impl-trait.rs:17:9
   |
LL | /     if true {
LL | |         S
   | |         - expected because of this
LL | |     } else {
LL | |         Y
   | |         ^ expected struct `S`, found struct `Y`
LL | |     }
   | |_____- `if` and `else` have incompatible types
   |
help: you could change the return type to be a boxed trait object
   |
LL | fn foo() -> Box<dyn Trait> {
   |             ~~~~~~~      +
help: if you change the return type to expect trait objects, box the returned expressions
   |
LL ~         Box::new(S)
LL |     } else {
LL ~         Box::new(Y)
   |

error[E0308]: `match` arms have incompatible types
  --> $DIR/suggest-boxed-trait-objects-instead-of-impl-trait.rs:24:18
   |
LL | /     match true {
LL | |         true => S,
   | |                 - this is found to be of type `S`
LL | |         false => Y,
   | |                  ^ expected struct `S`, found struct `Y`
LL | |     }
   | |_____- `match` arms have incompatible types
   |
help: you could change the return type to be a boxed trait object
   |
LL | fn bar() -> Box<dyn Trait> {
   |             ~~~~~~~      +
help: if you change the return type to expect trait objects, box the returned expressions
   |
LL ~         true => Box::new(S),
LL ~         false => Box::new(Y),
   |

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0308`.