qapi: Convert QType into QAPI built-in enum type

What's more meta than using qapi to define qapi? :)

Convert QType into a full-fledged[*] builtin qapi enum type, so
that a subsequent patch can then use it as the discriminator
type of qapi alternate types.  Fortunately, the judicious use of
'prefix' in the qapi definition avoids churn to the spelling of
the enum constants.

To avoid circular definitions, we have to flip the order of
inclusion between "qobject.h" vs. "qapi-types.h".  Back in commit
28770e0, we had the latter include the former, so that we could
use 'QObject *' for our implementation of 'any'.  But that usage
also works with only a forward declaration, whereas the
definition of QObject requires QType to be a complete type.

[*] The type has to be builtin, rather than declared in
qapi/common.json, because we want to use it for alternates even
when common.json is not included. But since it is the first
builtin enum type, we have to add special cases to qapi-types
and qapi-visit to only emit definitions once, even when two
qapi files are being compiled into the same binary (the way we
already handled builtin list types like 'intList').  We may
need to revisit how multiple qapi files share common types,
but that's a project for another day.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1449033659-25497-4-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/qapi-schema/union-clash-data.out b/tests/qapi-schema/union-clash-data.out
index cea8551c4c..f5752f4595 100644
--- a/tests/qapi-schema/union-clash-data.out
+++ b/tests/qapi-schema/union-clash-data.out
@@ -1,6 +1,8 @@
 object :empty
 object :obj-int-wrapper
     member data: int optional=False
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 object TestUnion
     member type: TestUnionKind optional=False
     case data: :obj-int-wrapper