error[E0658]: using an imported function as entry point `main` is experimental
  --> $DIR/feature-gate-imported_main.rs:6:5
   |
LL | use foo::bar as main;
   |     ^^^^^^^^^^^^^^^^
   |
   = note: see issue #28937 <https://github.com/rust-lang/rust/issues/28937> for more information
   = help: add `#![feature(imported_main)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0658`.