Re: [PATCH v3 1/8] reset: allow registering handlers that aren't called by snapshot loading

[Markus Armbruster <armbru@redhat.com>]

Peter Maydell <peter.maydell@linaro.org> writes:

> On Mon, 24 Oct 2022 at 13:28, Markus Armbruster <armbru@redhat.com> wrote:
>>
>> Peter Maydell <peter.maydell@linaro.org> writes:
>> > Markus: if we add a new value to the ShutdownCause enumeration,
>> > how annoying is it if we decide we don't want it later? I guess
>> > we can just leave it in the enum unused... (In this case we're
>> > using it for purely internal purposes and it won't ever actually
>> > wind up in any QMP events.)
>>
>> Deleting enumeration values is a compatibility issue only if the value
>> is usable in QMP input.
>>
>> "Purely internal" means it cannot occur in QMP output, and any attempt
>> to use it in input fails.  Aside: feels a bit fragile.
>
> In this case there are as far as I can see no QMP input commands
> which use the enum at all -- it's only used in events, which are
> always output, I think.

They are.

Ascertaining "not used in QMP input" is pretty easy, and "not used in
CLI" isn't hard.  My point is that uses could creep in later.  This is
what makes "purely internal" fragile.