See #8076. Skip arg and type check on re-declare of QQ if declare type is classic.

deps/rabbit/priv/schema/rabbit.schema

@@ -2483,6 +2483,8 @@ end}.
 {mapping, "quorum_queue.compute_checksums", "rabbit.quorum_compute_checksums", [
     {datatype, {enum, [true, false]}}]}.
 
+{mapping, "quorum_queue.property_equivalence.relaxed_checks_on_redeclaration", "rabbit.quorum_relaxed_checks_on_redeclaration", [
+    {datatype, {enum, [true, false]}}]}.
 
 %%
 %% Runtime parameters

deps/rabbit/src/rabbit_amqqueue.erl

@@ -652,13 +652,54 @@ priv_absent(QueueName, QPid, _IsDurable, alive) ->
             'ok' | rabbit_types:channel_exit() | rabbit_types:connection_exit().
 
 assert_equivalence(Q, DurableDeclare, AutoDeleteDeclare, Args1, Owner) ->
+    case equivalence_check_level(Q, Args1) of
+        full_check ->
+            perform_full_equivalence_checks(Q, DurableDeclare, AutoDeleteDeclare,
+                                            Args1, Owner);
+        limited_check_on_qq_redeclaration ->
+            perform_limited_equivalence_checks_on_qq_redeclaration(Q, Args1)
+    end.
+
+equivalence_check_level(Q, NewArgs) ->
+    Relaxed = rabbit_misc:get_env(rabbit,
+                                  quorum_relaxed_checks_on_redeclaration,
+                                  false),
+    case Relaxed of
+        true ->
+            ExistingArgs = amqqueue:get_arguments(Q),
+            OldType = rabbit_misc:table_lookup(ExistingArgs, <<"x-queue-type">>),
+            NewType = rabbit_misc:table_lookup(NewArgs, <<"x-queue-type">>),
+            case {OldType, NewType} of
+                {{longstr, <<"quorum">>}, {longstr, <<"classic">>}} ->
+                    limited_check_on_qq_redeclaration;
+                _ ->
+                    full_check
+            end;
+        false ->
+            full_check
+    end.
+
+perform_full_equivalence_checks(Q, DurableDeclare, AutoDeleteDeclare, NewArgs, Owner) ->
     QName = amqqueue:get_name(Q),
     DurableQ = amqqueue:is_durable(Q),
     AutoDeleteQ = amqqueue:is_auto_delete(Q),
     ok = check_exclusive_access(Q, Owner, strict),
     ok = rabbit_misc:assert_field_equivalence(DurableQ, DurableDeclare, QName, durable),
     ok = rabbit_misc:assert_field_equivalence(AutoDeleteQ, AutoDeleteDeclare, QName, auto_delete),
-    ok = assert_args_equivalence(Q, Args1).
+    ok = assert_args_equivalence(Q, NewArgs).
+
+perform_limited_equivalence_checks_on_qq_redeclaration(Q, NewArgs) ->
+    QName = amqqueue:get_name(Q),
+    ExistingArgs = amqqueue:get_arguments(Q),
+    CheckTypeArgs = [<<"x-dead-letter-exchange">>,
+                     <<"x-dead-letter-routing-key">>,
+                     <<"x-expires">>,
+                     <<"x-max-length">>,
+                     <<"x-max-length-bytes">>,
+                     <<"x-single-active-consumer">>,
+                     <<"x-message-ttl">>],
+    ok = rabbit_misc:assert_args_equivalence(ExistingArgs, NewArgs, QName, CheckTypeArgs).
+
 
 -spec augment_declare_args(vhost:name(), boolean(),
                            boolean(), boolean(),

deps/rabbit/test/quorum_queue_SUITE.erl

@@ -107,6 +107,7 @@ all_tests() ->
      declare_invalid_arg_1,
      declare_invalid_arg_2,
      declare_invalid_arg_3,
+     redeclare_qq_as_classic,
      consume_invalid_arg_1,
      consume_invalid_arg_2,
      start_queue,
@@ -416,6 +417,45 @@ declare_invalid_arg_3(Config) ->
        declare(Ch, Q, [{<<"x-queue-type">>, longstr, <<"quorum">>},
                        {<<"x-max-length">>, long, -5}])).
 
+
+redeclare_qq_as_classic(Config) ->
+    ok = rabbit_ct_broker_helpers:rpc(Config, 0, application, set_env,
+                                      [rabbit, quorum_relaxed_checks_on_redeclaration, true]),
+    Node = rabbit_ct_broker_helpers:get_node_config(Config, 0, nodename),
+    VHost = <<"redeclarevhost">>,
+    User = ?config(rmq_username, Config),
+    ok = rabbit_ct_broker_helpers:add_vhost(Config, Node, VHost, User),
+    ok = rabbit_ct_broker_helpers:set_full_permissions(Config, User, VHost),
+    Conn = rabbit_ct_client_helpers:open_unmanaged_connection(Config, Node, VHost),
+    {ok, Ch} = amqp_connection:open_channel(Conn),
+    Q = atom_to_binary(?FUNCTION_NAME, utf8),
+
+    %% Declare a quorum queue
+    ?assertEqual({'queue.declare_ok', Q, 0, 0},
+                 declare(Ch, Q, [{<<"x-queue-type">>, longstr, <<"quorum">>},
+                                 {<<"x-expires">>, long, 1000}])),
+
+    %% re-declare it as 'classic' queue, which now is OK.
+    ?assertEqual({'queue.declare_ok', Q, 0, 0},
+                 declare(Ch, Q, [{<<"x-queue-type">>, longstr, <<"classic">>},
+                                 {<<"x-expires">>, long, 1000}])),
+    %% re-declare it as 'classic' queue, with classic only arguments ignored, so OK.
+    ?assertEqual({'queue.declare_ok', Q, 0, 0},
+                 declare(Ch, Q, [{<<"x-queue-type">>, longstr, <<"classic">>},
+                                 {<<"x-max-priority">>, byte, 5},
+                                 {<<"x-expires">>, long, 1000}])),
+    %% re-declare it as 'classic' queue, with shared arguments not part of original queue not OK,
+    ?assertExit(
+       {{shutdown, {server_initiated_close, 406, _}}, _},
+       declare(Ch, Q, [{<<"x-queue-type">>, longstr, <<"classic">>},
+                       {<<"x-message-ttl">>, long, 5},
+                       {<<"x-expires">>, long, 1000}])),
+
+    ok = rabbit_ct_broker_helpers:delete_vhost(Config, VHost),
+    ok = rabbit_ct_broker_helpers:rpc(Config, 0, application, set_env,
+                                      [rabbit, quorum_relaxed_checks_on_redeclaration, false]),
+    ok.
+
 consume_invalid_arg_1(Config) ->
     Server = rabbit_ct_broker_helpers:get_node_config(Config, 0, nodename),
     Ch = rabbit_ct_client_helpers:open_channel(Config, Server),