Keep track of the start of the argument block of a closure
@@ -335,6 +335,7 @@ pub(crate) fn rewrite_last_closure(
ref fn_decl,
ref body,
fn_decl_span: _,
+ fn_arg_span: _,
} = **closure;
let body = match body.kind {
ast::ExprKind::Block(ref block, _)
