error: unused attribute
  --> $DIR/lint-unknown-attr.rs:19:1
   |
LL | #[dance] mod a {} //~ ERROR unused attribute
   | ^^^^^^^^
   |
note: lint level defined here
  --> $DIR/lint-unknown-attr.rs:15:9
   |
LL | #![deny(unused_attributes)]
   |         ^^^^^^^^^^^^^^^^^

error: unused attribute
  --> $DIR/lint-unknown-attr.rs:21:1
   |
LL | #[dance] fn main() {} //~ ERROR unused attribute
   | ^^^^^^^^

error: unused attribute
  --> $DIR/lint-unknown-attr.rs:17:1
   |
LL | #![mutable_doc] //~ ERROR unused attribute
   | ^^^^^^^^^^^^^^^

error: aborting due to 3 previous errors