cargo fmt --all succeeds but --check fails

[gnzlbg]

In these two files: https://gist.github.com/gnzlbg/fda65f2f8bd7b8517be4b8db1fbc7d73

cargo fmt --all succeeds, but cargo fmt --all -- --check fails.

cc @nrc @topecongiro

[gnzlbg]

This is currently triggered in packed_simd master, e.g., in this commit: rust-lang/packed_simd@d8b1472

It also feels like rustfmt fails to properly align the comment, e.g., it aligns the // comment differently than the /* */ one.

The other issue appears to be that --check detects a missing trailing comma, but cargo fmt --all doesn't add it.

[topecongiro]

A minimal example:

macro_rules! foo {
    () => {
        // comment
        /*

        */
    };
}

Diff:

 macro_rules! foo {
     () => {
         // comment
-        /*
+                /*
 
-        */
+                */
     };
 }

[scampi]

I will try to check this one