// previously appeared within a `Binder<>` and hence would not
// have been normalized before.
let fn_sig = self.replace_bound_vars_with_fresh_vars(call_expr.span, infer::FnCall, fn_sig);
// previously appeared within a `Binder<>` and hence would not
// have been normalized before.
let fn_sig = self.replace_bound_vars_with_fresh_vars(call_expr.span, infer::FnCall, fn_sig);