qapi: Fix generated code when flat union has member 'kind'

A flat union's tag member gets renamed to 'kind' in the generated
code.  Breaks when another member named 'kind' exists.

Example, adapted from qapi-schema-test.json:

    { 'struct': 'UserDefUnionBase',
      'data': { 'kind': 'str', 'enum1': 'EnumOne' } }

We generate:

    struct UserDefFlatUnion
    {
        EnumOne kind;
        union {
            void *data;
            UserDefA *value1;
            UserDefB *value2;
            UserDefB *value3;
        };
        char *kind;
    };

Kill the silly rename.

Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

2 files changed, 7 insertions, 3 deletions

diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index 4902440ce3..ac8dad3171 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -200,11 +200,12 @@ def generate_union(expr, meta):
     ret = mcgen('''
 struct %(name)s
 {
-    %(discriminator_type_name)s kind;
+    %(discriminator_type_name)s %(discriminator)s;
     union {
         void *data;
 ''',
                 name=name,
+                discriminator=c_name(discriminator or 'kind'),
                 discriminator_type_name=c_name(discriminator_type_name))
 
     for key in typeinfo:
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index e8ee2688e6..4ec79a6db8 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -288,20 +288,23 @@ void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **e
                      name=c_name(name))
 
     if not discriminator:
+        tag = 'kind'
         disc_key = "type"
     else:
+        tag = discriminator
         disc_key = discriminator
     ret += mcgen('''
-        visit_type_%(disc_type)s(m, &(*obj)->kind, "%(disc_key)s", &err);
+        visit_type_%(disc_type)s(m, &(*obj)->%(c_tag)s, "%(disc_key)s", &err);
         if (err) {
             goto out_obj;
         }
         if (!visit_start_union(m, !!(*obj)->data, &err) || err) {
             goto out_obj;
         }
-        switch ((*obj)->kind) {
+        switch ((*obj)->%(c_tag)s) {
 ''',
                  disc_type = disc_type,
+                 c_tag=c_name(tag),
                  disc_key = disc_key)
 
     for key in members: