Attributes on macro does not trigger error or warning

Using rustc 1.25.0-nightly (9fd7da904 2018-01-25),

fn foo() {
    println!("hello world");
}

fn main() {
    #[rustfmt_skip]
    foo ();
}

the abvoe code triggers an error:

error[E0658]: The attribute `rustfmt_skip` is currently unknown to the compiler and may have meaning added to it in the future (see issue #29642)
  --> test.rs:18:5
   |
18 |     #[rustfmt_skip]
   |     ^^^^^^^^^^^^^^^
   |
   = help: add #![feature(custom_attribute)] to the crate attributes to enable

error: aborting due to previous error

However, the following code compiles without any error:

fn main() {
    #[rustfmt_skip]
    println! ("hello world");
}

It looks like the attributes on macros are entirely ignored from the compiler. Is this an expected behavior?

1. Two potentially relevant comments?—

   https://github.com/rust-lang/rust/blob/8ccab7eed5f4fc93500fbf242e575073ca70d7cb/src/libsyntax/visit.rs#L110-L117

   https://github.com/rust-lang/rust/blob/8ccab7eed5f4fc93500fbf242e575073ca70d7cb/src/libsyntax/feature_gate.rs#L1101-L1111

   Zack M. Davis at 2018-02-01 00:57:37

2. This no longer produces a compiler error (playground):

   fn foo() {
       println!("hello world");
   }
   
   fn main() {
       #[rustfmt::skip]
       foo ();
       
       #[rustfmt::skip]
       println! ("hello world");
   }
   

   hello world
   hello world
   

   Can we close?

   Ben Reeves at 2021-12-29 04:03:26