error[E0601]: `main` function not found in crate `cfg_attr_cfg_2`
  --> $DIR/cfg-attr-cfg-2.rs:9:14
   |
LL | fn main() { }
   |              ^ consider adding a `main` function to `$DIR/cfg-attr-cfg-2.rs`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0601`.