error: invalid `?` in type
  --> $DIR/issue-103748-ICE-wrong-braces.rs:3:36
   |
LL | struct Apple((Apple, Option(Banana ? Citron)));
   |                                    ^ `?` is only allowed on expressions, not types
   |
help: if you meant to express that the type might not contain a value, use the `Option` wrapper type
   |
LL - struct Apple((Apple, Option(Banana ? Citron)));
LL + struct Apple((Apple, Option(Option<Banana > Citron)));
   |

error: unexpected token: `Citron`
  --> $DIR/issue-103748-ICE-wrong-braces.rs:3:38
   |
LL | struct Apple((Apple, Option(Banana ? Citron)));
   |                                      ^^^^^^ unexpected token after this

error: aborting due to 2 previous errors