Moving in macros can produce `value moved here in previous iteration of loop` without any loops

[Zoxc]

Test case:

macro_rules! test {
    ($v:expr) => {{
        drop(&$v);
        $v
    }}
}

fn main() {
    let b = Box::new(true);
    test!({b});
}

Produces:

error[E0382]: use of moved value: `b`
  --> src/main.rs:10:12
   |
10 |     test!({b});
   |            ^ value moved here in previous iteration of loop
   |
   = note: move occurs because `b` has type `std::boxed::Box<bool>`, which does not implement the `Copy` trait

[Ekleog]

This is likely due to https://github.com/rust-lang/rust/blob/master/src/librustc_borrowck/borrowck/mod.rs#L724-L732