[Qemu-devel] [PATCH v9 07/37] 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 pass NULL rather than "" as
the 'kind' parameter (matching most other uses where obj is NULL).

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

---
v9: save churn in declaration order for later series on boxed params,
drop Marc-Andre's R-b
v8: no change
v7: place earlier in series, adjust handling of 'kind'
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 | 12 +++++-------
 scripts/qapi.py       |  5 +++--
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 720486f..761cda9 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -61,25 +61,23 @@ def gen_event_send(name, arg_type):
     if arg_type and arg_type.members:
         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, NULL, "%(name)s", 0, &err);
 ''',
                      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 7dec611..497eaba 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1636,7 +1636,8 @@ 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'
@@ -1664,7 +1665,7 @@ 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()
-- 
2.5.0