[PATCH RFC 5/5] block: Deprecate transaction type drive-backup

[Markus Armbruster <armbru@redhat.com>]

Several moons ago, Vladimir posted

    Subject: [PATCH v2 3/3] qapi: deprecate drive-backup
    Date: Wed,  5 May 2021 16:58:03 +0300
    Message-Id: <20210505135803.67896-4-vsementsov@virtuozzo.com>
    https://lists.gnu.org/archive/html/qemu-devel/2021-05/msg01394.html

with this

    TODO: We also need to deprecate drive-backup transaction action..
    But union members in QAPI doesn't support 'deprecated' feature. I tried
    to dig a bit, but failed :/ Markus, could you please help with it? At
    least by advice?

This is one way to resolve it.  Sorry it took so long.

John explored another way, namely adding feature flags to union
branches.  Could also be useful, say to add different features to
branches in multiple unions sharing the same tag enum.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qapi/transaction.json | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/qapi/transaction.json b/qapi/transaction.json
index d7fc73d7df..0be6f83f6d 100644
--- a/qapi/transaction.json
+++ b/qapi/transaction.json
@@ -41,6 +41,9 @@
 ##
 # @TransactionActionKind:
 #
+# Features:
+# @deprecated: Member @drive-backup is deprecated.  Use FIXME instead.
+#
 # Since: 6.1
 ##
 { 'enum': 'TransactionActionKind',
@@ -49,7 +52,7 @@
             'block-dirty-bitmap-disable', 'block-dirty-bitmap-merge',
             'blockdev-backup', 'blockdev-snapshot',
             'blockdev-snapshot-internal-sync', 'blockdev-snapshot-sync',
-            'drive-backup' ] }
+            { 'name': 'drive-backup', 'features': [ 'deprecated' ] } ] }
 
 ##
 # @AbortWrapper:
-- 
2.31.1