qapi: Tighten checking of unions

Previous commits demonstrated that the generator had several
flaws with less-than-perfect unions:
- a simple union that listed the same branch twice (or two variant
names that map to the same C enumerator, including the implicit
MAX sentinel) ended up generating invalid C code
- an anonymous union that listed two branches with the same qtype
ended up generating invalid C code
- the generator crashed on anonymous union attempts to use an
array type
- the generator was silently ignoring a base type for anonymous
unions
- the generator allowed unknown types or nested anonymous unions
as a branch in an anonymous union

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

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/qapi-schema/alternate-array.json b/tests/qapi-schema/alternate-array.json
index 25224c6..0da1a64 100644
--- a/tests/qapi-schema/alternate-array.json
+++ b/tests/qapi-schema/alternate-array.json
@@ -1,4 +1,4 @@
-# FIXME: we should not allow array branches in anonymous unions
+# we do not allow array branches in anonymous unions
 # TODO: should we support this?
 { 'type': 'One',
   'data': { 'name': 'str' } }