Daniel P. Berrangé <berra...@redhat.com> wrote: > 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.
Do we have an example for this? Because it looks really weird. I would expect that the "container" unit of that enumeration is #ifdef out of compilation somehow. Later, Juan.