Currently the error output for this:

#![feature(decl_macro)]

mod foo1 {
    pub macro foo() {}
}

mod foo3 {
    fn bar() {
        foo!();
    }
}

is

error: cannot find macro `foo` in this scope
 --> src/lib.rs:9:9
  |
9 |         foo!();
  |         ^^^
  |
  = note: consider importing this macro:
          crate::foo1::foo

However the "consider importing this macro" part should be
use crate::foo1::foo; to be consistent. (Maybe this change should happen only when decl_macro feature gate is enabled)