Re: [Qemu-devel] [PATCH RFC v2 07/47] qapi: Generate a nicer struct for flat unions

[Eric Blake]

On 07/01/2015 02:21 PM, Markus Armbruster wrote:
> The struct generated for a flat union is weird: the members of its
> base are at the end, except for the union tag, which is renamed to
> 'kind' and put at the beginning.

The renaming to 'kind' was a bug waiting to happen.  Consider this
example, which is broken before your series:

diff --git i/tests/qapi-schema/qapi-schema-test.json
w/tests/qapi-schema/qapi-schema-test.json
index c7eaa86..12c09e3 100644
--- i/tests/qapi-schema/qapi-schema-test.json
+++ w/tests/qapi-schema/qapi-schema-test.json
@@ -37,7 +37,7 @@
   'data': { 'string1': 'str', 'string2': 'str' } }

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

 { 'union': 'UserDefFlatUnion',
   'base': 'UserDefUnionBase',


leading to this compilation error during 'make check-unit':

In file included from tests/test-qmp-output-visitor.c:17:0:
tests/test-qapi-types.h:617:11: error: duplicate member ‘kind’
     char *kind;
           ^
tests/test-qapi-types.h:631:11: error: duplicate member ‘kind’
     char *kind;
           ^

Therefore, it might be worth mentioning that avoiding the rename to
'kind' is a bug fix, not just a nicer struct :)

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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