On Thu, Mar 16, 2023 at 01:31:04PM +0100, Markus Armbruster wrote: > Philippe Mathieu-Daudé <phi...@linaro.org> writes: > > > Per the C++ standard, empty enum are ill-formed. Do not generate > > them in order to avoid: > > > > In file included from qga/qga-qapi-emit-events.c:14: > > qga/qga-qapi-emit-events.h:20:1: error: empty enum is invalid > > 20 | } qga_QAPIEvent; > > | ^ > > > > Reported-by: Markus Armbruster <arm...@redhat.com> > > Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org> > > Two failures in "make check-qapi-schema" (which is run by "make check"): > > 1. Positive test case qapi-schema-test > > --- /work/armbru/qemu/bld-x86/../tests/qapi-schema/qapi-schema-test.out > +++ > @@ -19,7 +19,6 @@ > member enum2: EnumOne optional=True > member enum3: EnumOne optional=False > member enum4: EnumOne optional=True > -enum MyEnum > object Empty1 > object Empty2 > base Empty1 > > You forgot to update expected test output. No big deal. > > 2. Negative test case union-empty > > --- /work/armbru/qemu/bld-x86/../tests/qapi-schema/union-empty.err > +++ > @@ -1,2 +1,2 @@ > -union-empty.json: In union 'Union': > -union-empty.json:4: union has no branches > +union-empty.json: In struct 'Base': > +union-empty.json:3: member 'type' uses unknown type 'Empty' > stderr: > qapi-schema-test FAIL > union-empty FAIL > > The error message regresses. > > I can see two ways to fix this: > > (A) You can't just drop empty enumeration types on the floor. To not > generate code for them, you need to skip them wherever we > generate code for enumeration types. > > (B) Outlaw empty enumeration types. > > I recommend to give (B) a try, it's likely simpler.
Possible trap-door with (B), if we have any enums where *every* member is conditionalized on a CONFIG_XXX rule, there might be certain build scenarios where an enum suddenly becomes empty. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
