qapi: Don't special-case simple union wrappers

Simple unions were carrying a special case that hid their 'data'
QMP member from the resulting C struct, via the hack method
QAPISchemaObjectTypeVariant.simple_union_type().  But by using
the work we started by unboxing flat union and alternate
branches, coupled with the ability to visit the members of an
implicit type, we can now expose the simple union's implicit
type in qapi-types.h:

| struct q_obj_ImageInfoSpecificQCow2_wrapper {
|     ImageInfoSpecificQCow2 *data;
| };
|
| struct q_obj_ImageInfoSpecificVmdk_wrapper {
|     ImageInfoSpecificVmdk *data;
| };
...
| struct ImageInfoSpecific {
|     ImageInfoSpecificKind type;
|     union { /* union tag is @type */
|         void *data;
|-        ImageInfoSpecificQCow2 *qcow2;
|-        ImageInfoSpecificVmdk *vmdk;
|+        q_obj_ImageInfoSpecificQCow2_wrapper qcow2;
|+        q_obj_ImageInfoSpecificVmdk_wrapper vmdk;
|     } u;
| };

Doing this removes asymmetry between QAPI's QMP side and its
C side (both sides now expose 'data'), and means that the
treatment of a simple union as sugar for a flat union is now
equivalent in both languages (previously the two approaches used
a different layer of dereferencing, where the simple union could
be converted to a flat union with equivalent C layout but
different {} on the wire, or to an equivalent QMP wire form
but with different C representation).  Using the implicit type
also lets us get rid of the simple_union_type() hack.

Of course, now all clients of simple unions have to adjust from
using su->u.member to using su->u.member.data; while this touches
a number of files in the tree, some earlier cleanup patches
helped minimize the change to the initialization of a temporary
variable rather than every single member access.  The generated
qapi-visit.c code is also affected by the layout change:

|@@ -7393,10 +7393,10 @@ void visit_type_ImageInfoSpecific_member
|     }
|     switch (obj->type) {
|     case IMAGE_INFO_SPECIFIC_KIND_QCOW2:
|-        visit_type_ImageInfoSpecificQCow2(v, "data", &obj->u.qcow2, &err);
|+        visit_type_q_obj_ImageInfoSpecificQCow2_wrapper_members(v, &obj->u.qcow2, &err);
|         break;
|     case IMAGE_INFO_SPECIFIC_KIND_VMDK:
|-        visit_type_ImageInfoSpecificVmdk(v, "data", &obj->u.vmdk, &err);
|+        visit_type_q_obj_ImageInfoSpecificVmdk_wrapper_members(v, &obj->u.vmdk, &err);
|         break;
|     default:
|         abort();

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1458254921-17042-13-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

11 files changed, 13 insertions, 13 deletions

diff --git a/net/dump.c b/net/dump.c
index 61dec9d..94ac32a 100644
--- a/net/dump.c
+++ b/net/dump.c
@@ -189,7 +189,7 @@ int net_init_dump(const NetClientOptions *opts, const char *name,
     DumpNetClient *dnc;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_DUMP);
-    dump = opts->u.dump;
+    dump = opts->u.dump.data;
 
     assert(peer);
 
diff --git a/net/hub.c b/net/hub.c
index b6d44fd..6d90c6e 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -288,7 +288,7 @@ int net_init_hubport(const NetClientOptions *opts, const char *name,
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_HUBPORT);
     assert(!peer);
-    hubport = opts->u.hubport;
+    hubport = opts->u.hubport.data;
 
     net_hub_add_port(hubport->hubid, name);
     return 0;
diff --git a/net/l2tpv3.c b/net/l2tpv3.c
index 824161c..5c668f7 100644
--- a/net/l2tpv3.c
+++ b/net/l2tpv3.c
@@ -546,7 +546,7 @@ int net_init_l2tpv3(const NetClientOptions *opts,
     s->header_mismatch = false;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_L2TPV3);
-    l2tpv3 = opts->u.l2tpv3;
+    l2tpv3 = opts->u.l2tpv3.data;
 
     if (l2tpv3->has_ipv6 && l2tpv3->ipv6) {
         s->ipv6 = l2tpv3->ipv6;
diff --git a/net/net.c b/net/net.c
index 73cefbc..1a78edf 100644
--- a/net/net.c
+++ b/net/net.c
@@ -893,7 +893,7 @@ static int net_init_nic(const NetClientOptions *opts, const char *name,
     const NetLegacyNicOptions *nic;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_NIC);
-    nic = opts->u.nic;
+    nic = opts->u.nic.data;
 
     idx = nic_get_free_idx();
     if (idx == -1 || nb_nics >= MAX_NICS) {
@@ -1025,7 +1025,7 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
 
         /* Do not add to a vlan if it's a nic with a netdev= parameter. */
         if (opts->type != NET_CLIENT_OPTIONS_KIND_NIC ||
-            !opts->u.nic->has_netdev) {
+            !opts->u.nic.data->has_netdev) {
             peer = net_hub_add_port(net->has_vlan ? net->vlan : 0, NULL);
         }
     }
diff --git a/net/netmap.c b/net/netmap.c
index 1b42728..6fa2c41 100644
--- a/net/netmap.c
+++ b/net/netmap.c
@@ -420,7 +420,7 @@ static NetClientInfo net_netmap_info = {
 int net_init_netmap(const NetClientOptions *opts,
                     const char *name, NetClientState *peer, Error **errp)
 {
-    const NetdevNetmapOptions *netmap_opts = opts->u.netmap;
+    const NetdevNetmapOptions *netmap_opts = opts->u.netmap.data;
     struct nm_desc *nmd;
     NetClientState *nc;
     Error *err = NULL;
diff --git a/net/slirp.c b/net/slirp.c
index 9954160..95239bc 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -814,7 +814,7 @@ int net_init_slirp(const NetClientOptions *opts, const char *name,
     const char **dnssearch;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_USER);
-    user = opts->u.user;
+    user = opts->u.user.data;
 
     vnet = user->has_net ? g_strdup(user->net) :
            user->has_ip  ? g_strdup_printf("%s/24", user->ip) :
diff --git a/net/socket.c b/net/socket.c
index 73dc49a..9826efb 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -704,7 +704,7 @@ int net_init_socket(const NetClientOptions *opts, const char *name,
     const NetdevSocketOptions *sock;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_SOCKET);
-    sock = opts->u.socket;
+    sock = opts->u.socket.data;
 
     if (sock->has_fd + sock->has_listen + sock->has_connect + sock->has_mcast +
         sock->has_udp != 1) {
diff --git a/net/tap-win32.c b/net/tap-win32.c
index 38bbac0..f1e142a 100644
--- a/net/tap-win32.c
+++ b/net/tap-win32.c
@@ -795,7 +795,7 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
     const NetdevTapOptions *tap;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_TAP);
-    tap = opts->u.tap;
+    tap = opts->u.tap.data;
 
     if (!tap->has_ifname) {
         error_report("tap: no interface name");
diff --git a/net/tap.c b/net/tap.c
index cd7a7fc..8f790d1 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -565,7 +565,7 @@ int net_init_bridge(const NetClientOptions *opts, const char *name,
     int fd, vnet_hdr;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_BRIDGE);
-    bridge = opts->u.bridge;
+    bridge = opts->u.bridge.data;
 
     helper = bridge->has_helper ? bridge->helper : DEFAULT_BRIDGE_HELPER;
     br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
@@ -728,7 +728,7 @@ int net_init_tap(const NetClientOptions *opts, const char *name,
     char ifname[128];
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_TAP);
-    tap = opts->u.tap;
+    tap = opts->u.tap.data;
     queues = tap->has_queues ? tap->queues : 1;
     vhostfdname = tap->has_vhostfd ? tap->vhostfd : NULL;
 
diff --git a/net/vde.c b/net/vde.c
index 973faf5..9427eaa 100644
--- a/net/vde.c
+++ b/net/vde.c
@@ -116,7 +116,7 @@ int net_init_vde(const NetClientOptions *opts, const char *name,
     const NetdevVdeOptions *vde;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_VDE);
-    vde = opts->u.vde;
+    vde = opts->u.vde.data;
 
     /* missing optional values have been initialized to "all bits zero" */
     if (net_vde_init(peer, "vde", name, vde->sock, vde->port, vde->group,
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 58b8dae..1b9e73a 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -306,7 +306,7 @@ int net_init_vhost_user(const NetClientOptions *opts, const char *name,
     CharDriverState *chr;
 
     assert(opts->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
-    vhost_user_opts = opts->u.vhost_user;
+    vhost_user_opts = opts->u.vhost_user.data;
 
     chr = net_vhost_parse_chardev(vhost_user_opts, errp);
     if (!chr) {