error: `proc-macro` crate types currently cannot export any items other than functions tagged with `#[proc_macro]`, `#[proc_macro_derive]`, or `#[proc_macro_attribute]`
  --> $DIR/exports.rs:7:1
   |
LL | pub fn a() {}
   | ^^^^^^^^^^^^^

error: `proc-macro` crate types currently cannot export any items other than functions tagged with `#[proc_macro]`, `#[proc_macro_derive]`, or `#[proc_macro_attribute]`
  --> $DIR/exports.rs:8:1
   |
LL | pub struct B;
   | ^^^^^^^^^^^^^

error: `proc-macro` crate types currently cannot export any items other than functions tagged with `#[proc_macro]`, `#[proc_macro_derive]`, or `#[proc_macro_attribute]`
  --> $DIR/exports.rs:9:1
   |
LL | pub enum C {}
   | ^^^^^^^^^^^^^

error: `proc-macro` crate types currently cannot export any items other than functions tagged with `#[proc_macro]`, `#[proc_macro_derive]`, or `#[proc_macro_attribute]`
  --> $DIR/exports.rs:10:1
   |
LL | pub mod d {}
   | ^^^^^^^^^^^^

error: aborting due to 4 previous errors