[Qemu-devel] [PATCH v6 15/23] qapi: Improve generated event use of qapi visitor

[Eric Blake <eblake@redhat.com>]

All other successful clients of visit_start_struct() were paired
with an unconditional visit_end_struct(); but the generated
code for events was relying on qmp_output_visitor_cleanup() to
work on an incomplete visit.  Alter the code to guarantee that
the struct is completed, which will make a future patch to
split visit_end_struct() easier to reason about.  While at it,
drop some assertions and comments that are not present in other
uses of the qmp output visitor, and rearrange the declaration
to make it easier for a future patch to introduce the notion of
a boxed event visit.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v6: new patch

If desired, I can defer the hunk re-ordering the declaration of
obj to later in the series where it actually comes in handy.
---
 scripts/qapi-event.py | 19 ++++++++++---------
 scripts/qapi.py       |  5 +++--
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 51128f4..5dc9726 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -41,9 +41,9 @@ def gen_event_send(name, arg_type):

     if arg_type and not arg_type.is_empty():
         ret += mcgen('''
+    QObject *obj;
     QmpOutputVisitor *qov;
     Visitor *v;
-    QObject *obj;

 ''')

@@ -59,27 +59,28 @@ def gen_event_send(name, arg_type):
                  name=name)

     if arg_type and not arg_type.is_empty():
+        c_name = 'NULL'
+        if not arg_type.is_implicit():
+            c_name = '"%s"' % arg_type.c_name()
         ret += mcgen('''
     qov = qmp_output_visitor_new();
-    g_assert(qov);
-
     v = qmp_output_get_visitor(qov);
-    g_assert(v);

-    /* Fake visit, as if all members are under a structure */
-    visit_start_struct(v, NULL, "", "%(name)s", 0, &err);
+    visit_start_struct(v, NULL, %(c_name)s, "%(name)s", 0, &err);
 ''',
-                     name=name)
+                     c_name=c_name, name=name)
         ret += gen_err_check()
-        ret += gen_visit_fields(arg_type.members, need_cast=True)
+        ret += gen_visit_fields(arg_type.members, need_cast=True,
+                                label='out_obj')
         ret += mcgen('''
+out_obj:
     visit_end_struct(v, &err);
     if (err) {
         goto out;
     }

     obj = qmp_output_get_qobject(qov);
-    g_assert(obj != NULL);
+    g_assert(obj);

     qdict_put_obj(qmp, "data", obj);
 ''')
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 45bc5a7..ed2a063 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1637,7 +1637,8 @@ def gen_err_check(label='out', skiperr=False):
                  label=label)


-def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
+def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
+                     label='out'):
     ret = ''
     if skiperr:
         errparg = 'NULL'
@@ -1665,7 +1666,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
                      c_type=memb.type.c_name(), prefix=prefix, cast=cast,
                      c_name=c_name(memb.name), name=memb.name,
                      errp=errparg)
-        ret += gen_err_check(skiperr=skiperr)
+        ret += gen_err_check(skiperr=skiperr, label=label)

         if memb.optional:
             pop_indent()
-- 
2.4.3