Re: [PATCH v3] target/s390x: filter deprecated properties based on model expansion type

[Markus Armbruster <armbru@redhat.com>]

Collin Walling <walling@linux.ibm.com> writes:

> On 7/25/24 3:39 AM, David Hildenbrand wrote:
>> On 25.07.24 09:35, Markus Armbruster wrote:
>>> Markus Armbruster <armbru@redhat.com> writes:

[...]

>>>> Arguments that are silently ignored is bad interface design.
>>>>
>>>> Observe: when CpuModelInfo is an argument, @deprecated-props is always
>>>> ignored.  When it's a return value, absent means {}, and it can be
>>>> present only for certain targets (currently S390).
>>>>
>>>> The reason we end up with an argument we ignore is laziness: we use the
>>>> same type for both roles.  We can fix that easily:
>>>>
>>>>      { 'struct': 'CpuModel',
>>>>        'data': { 'name': 'str',
>>>>                  '*props': 'any' } }
>>>>
>>>>      { 'struct': 'CpuModelInfo',
>>>>        'base': 'CpuModel',
>>>>        'data': { '*deprecated-props': ['str'] } }
>>>>
>>>> Use CpuModel for arguments, CpuModelInfo for return values.
>>>>
>>>> Since @deprecated-props is used only by some targets, I'd make it
>>>> conditional, i.e. 'if': 'TARGET_S390X'.
>>>
>>> If we want just query-cpu-model-expansion return deprecated properties,
>>> we can instead move @deprecated-props from CpuModelInfo to
>>> CpuModelExpansionInfo.
>> 
>> That might a bit more sense, because deprecated-props does not make any 
>> sense as input parameter, for example.
>
> Will do.  Thanks for the feedback.  v4 in the works.

We better get this into 9.1.  Plan B: mark @deprecated-props unstable to
avoid backward compatibility pain.