qapi: Require boxed for conditional command and event arguments

The C code generator fails to honor 'if' conditions of command and
event arguments.

For instance, tests/qapi-schema/qapi-schema-test.json has

    { 'event': 'TEST_IF_EVENT',
      'data': { 'foo': 'TestIfStruct',
		'bar': { 'type': ['str'], 'if': 'TEST_IF_EVT_ARG' } },
      'if': { 'all': ['TEST_IF_EVT', 'TEST_IF_STRUCT'] } }

Generated tests/test-qapi-events.h fails to honor the TEST_IF_EVT_ARG
condition:

    #if defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT)
    void qapi_event_send_test_if_event(TestIfStruct *foo, strList *bar);
    #endif /* defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT) */

Only uses so far are in tests/.

We could fix the generator to emit something like

    #if defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT)
    void qapi_event_send_test_if_event(TestIfStruct *foo
    #if defined(TEST_IF_EVT_ARG)
                    , strList *bar
    #endif
                    );
    #endif /* defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT) */

Ugly.  Calls become similarly ugly.  Not worth fixing.

Conditional arguments work fine with 'boxed': true, simply because
complex types with conditional members work fine.  Not worth breaking.

Reject conditional arguments unless boxed.

Move the tests cases covering unboxed conditional arguments out of
tests/qapi-schema/qapi-schema-test.json.  Cover boxed conditional
arguments there instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230316071325.492471-15-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

tests/qapi-schema/args-if-implicit.err

@@ -0,0 +1,2 @@
+args-if-implicit.json: In command 'test-if-cmd':
+args-if-implicit.json:1: conditional command arguments require 'boxed': true

tests/qapi-schema/args-if-implicit.json

@@ -0,0 +1,4 @@
+{ 'command': 'test-if-cmd',
+  'data': {
+    'foo': 'int',
+    'bar': { 'type': 'str', 'if': 'TEST_IF_CMD_ARG' } } }

tests/qapi-schema/args-if-unboxed.err

@@ -0,0 +1,2 @@
+args-if-unboxed.json: In command 'test-if-cmd':
+args-if-unboxed.json:5: conditional command arguments require 'boxed': true

tests/qapi-schema/args-if-unboxed.json

@@ -0,0 +1,6 @@
+{ 'struct': 'TestIfCmdArgs',
+  'data': {
+    'foo': 'int',
+    'bar': { 'type': 'str', 'if': 'TEST_IF_CMD_ARG' } } }
+{ 'command': 'test-if-cmd',
+  'data': 'TestIfCmdArgs' }

tests/qapi-schema/event-args-if-unboxed.err

@@ -0,0 +1,2 @@
+tests/qapi-schema/event-args-if-unboxed.json: In event 'TEST_IF_EVENT':
+tests/qapi-schema/event-args-if-unboxed.json:1: event's 'data' members may have 'if' conditions only with 'boxed': true

tests/qapi-schema/event-args-if-unboxed.json

@@ -0,0 +1,4 @@
+ { 'event': 'TEST_IF_EVENT',
+  'data': {
+    'foo': 'int',
+    'bar': { 'type': 'str', 'if': 'TEST_IF_CMD_ARG' } } }

tests/qapi-schema/meson.build

@@ -27,6 +27,8 @@ schemas = [
   'args-bad-boxed.json',
   'args-boxed-anon.json',
   'args-boxed-string.json',
+  'args-if-implicit.json',
+  'args-if-unboxed.json',
   'args-int.json',
   'args-invalid.json',
   'args-member-array-bad.json',

tests/qapi-schema/qapi-schema-test.json

@@ -249,17 +249,16 @@
   'if': { 'all': ['TEST_IF_ALT', 'TEST_IF_STRUCT'] } }
 
 { 'command': 'test-if-cmd',
-  'data': {
-    'foo': 'TestIfStruct',
-    'bar': { 'type': 'str', 'if': 'TEST_IF_CMD_ARG' } },
+  'boxed': true,
+  'data': 'TestIfStruct',
   'returns': 'UserDefThree',
   'if': { 'all': ['TEST_IF_CMD', 'TEST_IF_STRUCT'] } }
 
 { 'command': 'test-cmd-return-def-three', 'returns': 'UserDefThree' }
 
 { 'event': 'TEST_IF_EVENT',
-  'data': { 'foo': 'TestIfStruct',
-            'bar': { 'type': ['str'], 'if': 'TEST_IF_EVT_ARG' } },
+  'boxed': true,
+  'data': 'TestIfStruct',
   'if': { 'all': ['TEST_IF_EVT', 'TEST_IF_STRUCT'] } }
 
 { 'event': 'TEST_IF_EVENT2', 'data': {},

tests/qapi-schema/qapi-schema-test.out

@@ -283,23 +283,13 @@ object q_obj_test-if-alternate-cmd-arg
 command test-if-alternate-cmd q_obj_test-if-alternate-cmd-arg -> None
     gen=True success_response=True boxed=False oob=False preconfig=False
     if {'all': ['TEST_IF_ALT', 'TEST_IF_STRUCT']}
-object q_obj_test-if-cmd-arg
-    member foo: TestIfStruct optional=False
-    member bar: str optional=False
-        if TEST_IF_CMD_ARG
-    if {'all': ['TEST_IF_CMD', 'TEST_IF_STRUCT']}
-command test-if-cmd q_obj_test-if-cmd-arg -> UserDefThree
-    gen=True success_response=True boxed=False oob=False preconfig=False
+command test-if-cmd TestIfStruct -> UserDefThree
+    gen=True success_response=True boxed=True oob=False preconfig=False
     if {'all': ['TEST_IF_CMD', 'TEST_IF_STRUCT']}
 command test-cmd-return-def-three None -> UserDefThree
     gen=True success_response=True boxed=False oob=False preconfig=False
-object q_obj_TEST_IF_EVENT-arg
-    member foo: TestIfStruct optional=False
-    member bar: strList optional=False
-        if TEST_IF_EVT_ARG
-    if {'all': ['TEST_IF_EVT', 'TEST_IF_STRUCT']}
-event TEST_IF_EVENT q_obj_TEST_IF_EVENT-arg
-    boxed=False
+event TEST_IF_EVENT TestIfStruct
+    boxed=True
     if {'all': ['TEST_IF_EVT', 'TEST_IF_STRUCT']}
 event TEST_IF_EVENT2 None
     boxed=False