Bubble up opaque <eq> opaque operations instead of picking an order

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -328,19 +328,26 @@ fn check_opaque_type_well_formed<'tcx>(
 
     // Require that the hidden type actually fulfills all the bounds of the opaque type, even without
     // the bounds that the function supplies.
-    let opaque_ty = Ty::new_opaque(tcx, def_id.to_def_id(), identity_args);
-    ocx.eq(&ObligationCause::misc(definition_span, def_id), param_env, opaque_ty, definition_ty)
-        .map_err(|err| {
-            infcx
-                .err_ctxt()
-                .report_mismatched_types(
-                    &ObligationCause::misc(definition_span, def_id),
-                    opaque_ty,
-                    definition_ty,
-                    err,
-                )
-                .emit()
-        })?;
+    let mut obligations = vec![];
+    infcx
+        .insert_hidden_type(
+            OpaqueTypeKey { def_id, args: identity_args },
+            &ObligationCause::misc(definition_span, def_id),
+            param_env,
+            definition_ty,
+            true,
+            &mut obligations,
+        )
+        .unwrap();
+    infcx.add_item_bounds_for_hidden_type(
+        def_id.to_def_id(),
+        identity_args,
+        ObligationCause::misc(definition_span, def_id),
+        param_env,
+        definition_ty,
+        &mut obligations,
+    );
+    ocx.register_obligations(obligations);
 
     // Require the hidden type to be well-formed with only the generics of the opaque type.
     // Defining use functions may have more bounds than the opaque type, which is ok, as long as the