NOT token (!) inside a macro call inside `macro_rules!` erroneously de-indented (non-idempotency)

Minimal reproducer:

mod ok {
    mod ok {
        const _: &'static str = stringify!(Foo: !Bar);
    }
}

macro_rules! ok_2 {
    () => {
        const _: i32 = !1;
    };
}
ok_2!();

macro_rules! fail_dedented {
    () => {
        const _: &'static str = stringify!(Foo: !Bar);
    };
}
fail_dedented!();

macro_rules! fail_dedented_nonidempotent {
    () => {
        const _: () = assert!(stringify!(Foo: !Bar).len() > 0, concat!(stringify!(Foo: !Bar), "Lorem ipsum dolor sit amet, consectetur adipiscing elit"));
    };
}
fail_dedented_nonidempotent!();

macro_rules! fail_dedented_nonidempotent_2 {
    () => {
        const _: () = assert!(stringify!(Foo: !Bar).len() > 0, concat!(stringify!(Foo: !Bar), "Lorem ipsum dolor sit amet, consectetur adipiscing elit"));
    };
}

fail_dedented_nonidempotent_2!();

formats to

mod ok {
    mod ok {
        const _: &'static str = stringify!(Foo: !Bar);
    }
}

macro_rules! ok_2 {
    () => {
        const _: i32 = !1;
    };
}
ok_2!();

macro_rules! fail_dedented {
    () => {
const _: &'static str = stringify!(Foo: !Bar);
    };
}
fail_dedented!();

macro_rules! fail_dedented_nonidempotent {
    () => {
const _: () = assert!(
            stringify!(Foo: !Bar).len() > 0,
            concat!(
                stringify!(Foo: !Bar),
                "Lorem ipsum dolor sit amet, consectetur adipiscing elit"
            )
        );
    };
}
fail_dedented_nonidempotent!();

macro_rules! fail_dedented_nonidempotent_2 {
    () => {
const _: () = assert!(
            stringify!(Foo: !Bar).len() > 0,
            concat!(
                stringify!(Foo: !Bar),
                "Lorem ipsum dolor sit amet, consectetur adipiscing elit"
            )
        );
    };
}

fail_dedented_nonidempotent_2!();

formats to

mod ok {
    mod ok {
        const _: &'static str = stringify!(Foo: !Bar);
    }
}

macro_rules! ok_2 {
    () => {
        const _: i32 = !1;
    };
}
ok_2!();

macro_rules! fail_dedented {
    () => {
const _: &'static str = stringify!(Foo: !Bar);
    };
}
fail_dedented!();

macro_rules! fail_dedented_nonidempotent {
    () => {
        const _: () = assert!(
    stringify!(Foo: !Bar).len() > 0,
            concat!(
        stringify!(Foo: !Bar),
                "Lorem ipsum dolor sit amet, consectetur adipiscing elit"
            )
        );
    };
}
fail_dedented_nonidempotent!();

macro_rules! fail_dedented_nonidempotent_2 {
    () => {
        const _: () = assert!(
    stringify!(Foo: !Bar).len() > 0,
            concat!(
        stringify!(Foo: !Bar),
                "Lorem ipsum dolor sit amet, consectetur adipiscing elit"
            )
        );
    };
}

fail_dedented_nonidempotent_2!();

Start by running rustfmt on the minimal reproducer in the issue and compare the first and second formatting passes. The fix is done when the macro body is not incorrectly de-indented and formatting the result again produces identical output.