Using `-Z macro-backtrace` breaks 'unreachable statement' with macro call

[Aaron1011]

The following code:

fn main() {
    panic!("{}", 25);
    return ();
}

prints the following warning on nightly:

warning: unreachable statement
 --> panic_unreachable.rs:3:5
  |
2 |     panic!("{}", 25);
  |     ----------------- any code following this expression is unreachable
3 |     return ();
  |     ^^^^^^^^^^ unreachable statement
  |
  = note: `#[warn(unreachable_code)]` on by default

However, with -Z macro-backtrace, this warning is printed:

warning: unreachable statement
  --> panic_unreachable.rs:3:5
   |
3  |     return ();
   |     ^^^^^^^^^^ unreachable statement
   | 
  ::: /home/aaron/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/macros.rs:16:9
   |
16 |         $crate::rt::begin_panic_fmt(&$crate::format_args!($fmt, $($arg)+))
   |         ------------------------------------------------------------------ any code following this expression is unreachable
   |
   = note: `#[warn(unreachable_code)]` on by default

The original panic! call isn't even shown, making the "any code following this expression is unreachable" almost useless.

[oscarsun95]

I'm also trying to use -Z macro-bactrace (in nightly build).
Could you show your full command please?

[Aaron1011]

@oscarsun95: I used rustc main.rs -Z macro-backtrace