[Qemu-stable] [PATCH 2/3] qapi: dealloc visitor, implement visit_start_union

[Michael Roth]

If the .data field of a QAPI Union is NULL, we don't need to free
any of the union fields..

Make use of the new visit_start_union interface to access this
information and instruct the generated code to not visit these
fields when this occurs.

Cc: address@hidden
Reported-by: Fam Zheng <address@hidden>
Suggested-by: Paolo Bonzini <address@hidden>
Signed-off-by: Michael Roth <address@hidden>
---
 qapi/qapi-dealloc-visitor.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index dc53545..eb77078 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -162,6 +162,11 @@ static void qapi_dealloc_type_enum(Visitor *v, int *obj, 
const char *strings[],
 {
 }
 
+static bool qapi_dealloc_start_union(Visitor *v, bool data_present, Error 
**errp)
+{
+    return data_present;
+}
+
 Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)
 {
     return &v->visitor;
@@ -191,6 +196,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
     v->visitor.type_str = qapi_dealloc_type_str;
     v->visitor.type_number = qapi_dealloc_type_number;
     v->visitor.type_size = qapi_dealloc_type_size;
+    v->visitor.start_union = qapi_dealloc_start_union;
 
     QTAILQ_INIT(&v->stack);
 
-- 
1.9.1