On 05/02/2020 11:32, Neil Horman wrote:
> On Wed, Feb 05, 2020 at 11:04:29AM +0100, Luca Boccassi wrote:
>> On Tue, 2020-02-04 at 07:02 -0500, Neil Horman wrote:
>>>> But if we can do the versioning in the master, LTS can backport it
>>>> and can have
>>>> mature version of that API in LTS without breaking the existing
>>>> users.
>>>>
>>>
>>> But why bother? The only thing you've changed is the version
>>> tagging. Its ok
>>> to leave that alone in LTS, you just cant change it.
>>>
>>> Thats part of the burden of an LTS release, it will have some drift
>>> from the
>>> upstream head, because you have to keep things stable. So you
>>> stabilize the
>>> upstream ABI version for this API and just never backport it to the
>>> current LTS
>>> release.
>>
>> Hi,
>>
>> A customer (OVS) explicitly and specifically requested backporting the
>> symbol change to 19.11, as they don't want to enable experimental APIs
>> in their releases. I replied that it would only be acceptable with
>> aliasing to keep compatibility, and Ferruh very kindly did the work to
>> implement that.
>>
> but, thats part of the agreement, no? You can't always have new features and
> stability at the same time.
>
> I get that this is an odd corner case, because strictly speaking you could
> waive
> the ABI change that libabigail is reporting, and most application users (like
> OVS) could get away with it, because their application does all the right
> things
> to make it ok, but I don't think you can make a decsion like this for all
> users
> based on the request of a single user.
>
> It seems like the right thing is for OVS to augment their build time
> configuration to allow developers to select the ability to use experimental
> apis
> at compile time, and then the decision is placed in the hands of end users.
So this is not isolated case right ... it is common from API's to graduate
from experimental to mature, we _want_ that to happen, we _want_ APIs to
mature.
I am worried what you are proposing will encourage a behavior whereby
maintainers
to wait until the declaration of the next major ABI version to make these
symbol changes,
causing these kinds of changes to queue up for that release.
And you would have to ask why?
In the case of a reasonably mature API, there will be no functional or
signature change - its mature!
So what is the harm of providing an alias back to Experimental until the next
ABI version is declared?
So while yes, you are 100% right - experimental mean no guarantees.
But if the API is baked, it is not going to change, so I don't see the harm.
We don't want the unnecessary triumph of policy over pragmatism.
