qapi script: do not allow string discriminator

Since enum based discriminators provide better type-safety and
ensure that future qapi additions do not forget to adjust dependent
unions, forbid using string as discriminator from now on.

Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/qapi-schema/flat-union-string-discriminator.json b/tests/qapi-schema/flat-union-string-discriminator.json
new file mode 100644
index 0000000000..e966aeb395
--- /dev/null
+++ b/tests/qapi-schema/flat-union-string-discriminator.json
@@ -0,0 +1,17 @@
+{ 'enum': 'TestEnum',
+  'data': [ 'value1', 'value2' ] }
+
+{ 'type': 'TestBase',
+  'data': { 'enum1': 'TestEnum', 'kind': 'str' } }
+
+{ 'type': 'TestTypeA',
+  'data': { 'string': 'str' } }
+
+{ 'type': 'TestTypeB',
+  'data': { 'integer': 'int' } }
+
+{ 'union': 'TestUnion',
+  'base': 'TestBase',
+  'discriminator': 'kind',
+  'data': { 'kind1': 'TestTypeA',
+            'kind2': 'TestTypeB' } }