error: struct `T` is never constructed
  --> $DIR/unused-struct-derive-default.rs:4:8
   |
LL | struct T;
   |        ^
   |
   = note: `T` has a derived impl for the trait `Default`, but this is intentionally ignored during dead code analysis
note: the lint level is defined here
  --> $DIR/unused-struct-derive-default.rs:1:9
   |
LL | #![deny(dead_code)]
   |         ^^^^^^^^^

error: variant `B` is never constructed
  --> $DIR/unused-struct-derive-default.rs:13:5
   |
LL | enum E {
   |      - variant in this enum
...
LL |     B,
   |     ^

error: aborting due to 2 previous errors