def_id,
);
+ if fn_sig.abi == abi::Abi::RustCall {
+ let sp = arg_exprs.last().map_or(call_expr.span, |expr| expr.span);
+ if let Some(ty) = fn_sig.inputs().last().copied() {
+ self.register_bound(
+ ty,
+ self.tcx.require_lang_item(hir::LangItem::Tuple, Some(sp)),
+ traits::ObligationCause::new(sp, self.body_id, traits::RustCall),
+ );
+ } else {
+ self.tcx.sess.span_err(
+ sp,
+ "functions with the \"rust-call\" ABI must take a single non-self tuple argument",
+ );
+ }
+ }
+
fn_sig.output()
}