1 error[E0596]: cannot borrow immutable local variable `foo` as mutable
2 --> $DIR/span-covering-argument-1.rs:15:19
5 | -- consider changing this to `mut $s`
7 | ^^ cannot borrow mutably
9 22 | bad!(foo whatever);
10 | ------------------- in this macro invocation
12 error: aborting due to previous error