qapi: Smooth another visitor error checking pattern

Convert

    visit_type_FOO(v, ..., &ptr, &err);
    ...
    if (err) {
        ...
    }

to

    visit_type_FOO(v, ..., &ptr, errp);
    ...
    if (!ptr) {
        ...
    }

for functions that set @ptr to non-null / null on success / error.

Eliminate error_propagate() that are now unnecessary.  Delete @err
that are now unused.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-40-armbru@redhat.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index 96c6c009c7..a775fba7c0 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -682,11 +682,9 @@ static char *xen_block_blockdev_add(const char *id, QDict *qdict,
     trace_xen_block_blockdev_add(node_name);
 
     v = qobject_input_visitor_new(QOBJECT(qdict));
-    visit_type_BlockdevOptions(v, NULL, &options, &local_err);
+    visit_type_BlockdevOptions(v, NULL, &options, errp);
     visit_free(v);
-
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (!options) {
         goto fail;
     }