1 error[E0596]: cannot borrow `foo` as mutable, as it is not declared as mutable
2 --> $DIR/span-covering-argument-1.rs:5:14
5 | -- help: consider changing this to be mutable: `mut foo`
7 | ^^^^^^^ cannot borrow as mutable
9 LL | bad!(foo whatever);
10 | ------------------- in this macro invocation
12 = note: this error originates in the macro `bad` (in Nightly builds, run with -Z macro-backtrace for more info)
14 error: aborting due to previous error
16 For more information about this error, try `rustc --explain E0596`.