Add IMPLIED_BOUNDS_ENTAILMENT lint

compiler/rustc_infer/src/infer/mod.rs

@@ -1693,7 +1693,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         generic_param_scope: LocalDefId,
         outlives_env: &OutlivesEnvironment<'tcx>,
-    ) {
+    ) -> Option<ErrorGuaranteed> {
         let errors = self.resolve_regions(outlives_env);
 
         if let None = self.tainted_by_errors() {
@@ -1704,6 +1704,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             // errors from silly ones.
             self.report_region_errors(generic_param_scope, &errors);
         }
+
+        (!errors.is_empty()).then(|| {
+            self.tcx.sess.delay_span_bug(rustc_span::DUMMY_SP, "error should have been emitted")
+        })
     }
 
     // [Note-Type-error-reporting]