expr.span,
&format!("calling `to_string` on `{arg_ty}`"),
|diag| {
- diag.help(&format!(
+ diag.help(format!(
"`{self_ty}` implements `ToString` through a slower blanket impl, but `{deref_self_ty}` has a fast specialization of `ToString`"
));
let mut applicability = Applicability::MachineApplicable;