check_name() consists of check_name_is_str() and check_name_str().
check_union() relies on the latter to catch optional discriminators.
The next commit will replace that by a more straightforward check.
Inlining check_name() into check_union() now should make that easier
to review.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190927134639.4284-16-armbru@redhat.com>
---
 scripts/qapi/common.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index 88945804dc..9acff01d3e 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -897,8 +897,10 @@ def check_union(expr, info):
 
         # The value of member 'discriminator' must name a non-optional
         # member of the base struct.
-        check_name(discriminator, info,
-                   "discriminator of flat union '%s'" % name)
+        check_name_is_str(discriminator, info,
+                          "discriminator of flat union '%s'" % name)
+        check_name_str(discriminator, info,
+                       "discriminator of flat union '%s'" % name)
         discriminator_value = base_members.get(discriminator)
         if not discriminator_value:
             raise QAPISemError(info,
-- 
2.21.0