nyaaa 🤔

Author: lcnr

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -615,6 +615,14 @@ fn apply_defining_uses<'tcx>(
             ),
         ) {
             root_cx.add_concrete_opaque_type(key.def_id, OpaqueHiddenType::new_error(tcx, guar));
+        } else {
+            let opaque_types = infcx.take_opaque_types();
+            if !opaque_types.is_empty() {
+                tcx.dcx().span_delayed_bug(
+                    hidden_type.span,
+                    format!("unsupported recursive opaque type definition: {:?}", opaque_types),
+                );
+            }
         }
     }
 }