2 use rustc_errors::struct_span_err;
4 use rustc_hir::itemlikevisit::ItemLikeVisitor;
5 use rustc_span::symbol::sym;
7 pub fn test_variance(tcx: TyCtxt<'_>) {
8 tcx.hir().krate().visit_all_item_likes(&mut VarianceTest { tcx });
11 struct VarianceTest<'tcx> {
15 impl ItemLikeVisitor<'tcx> for VarianceTest<'tcx> {
16 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
17 let item_def_id = self.tcx.hir().local_def_id(item.hir_id);
19 // For unit testing: check for a special "rustc_variance"
20 // attribute and report an error with various results if found.
21 if self.tcx.has_attr(item_def_id, sym::rustc_variance) {
22 let variances_of = self.tcx.variances_of(item_def_id);
23 struct_span_err!(self.tcx.sess, item.span, E0208, "{:?}", variances_of).emit();
27 fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem<'tcx>) {}
28 fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem<'tcx>) {}