error: struct `Foo` is never constructed
  --> tests/fail/deny_lint.rs:LL:CC
   |
LL | struct Foo;
   |        ^^^
   |
note: the lint level is defined here
  --> tests/fail/deny_lint.rs:LL:CC
   |
LL | #![deny(warnings, unused)]
   |                   ^^^^^^
   = note: `#[deny(dead_code)]` implied by `#[deny(unused)]`

error: miri cannot be run on programs that fail compilation

error: aborting due to 2 previous errors