error[E0600]: cannot apply unary operator `!` to type `&'static str`
  --> $DIR/E0600.rs:12:5
   |
LL |     !"a"; //~ ERROR E0600
   |     ^^^^
   |
   = note: an implementation of `std::ops::Not` might be missing for `&'static str`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0600`.