src/librustc_typeck/variance/test.rs

   1 use rustc_errors::struct_span_err;
   2 use rustc_hir as hir;
   3 use rustc_hir::itemlikevisit::ItemLikeVisitor;
   4 use rustc_middle::ty::TyCtxt;
   5 use rustc_span::symbol::sym;
   6
   7 pub fn test_variance(tcx: TyCtxt<'_>) {
   8     tcx.hir().krate().visit_all_item_likes(&mut VarianceTest { tcx });
   9 }
  10
  11 struct VarianceTest<'tcx> {
  12     tcx: TyCtxt<'tcx>,
  13 }
  14
  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);
  18
  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.to_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();
  24         }
  25     }
  26
  27     fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem<'tcx>) {}
  28     fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem<'tcx>) {}
  29 }