Experimental Physics and
Industrial Control System

"J. Lewis Muir via Core-talk" <core-talk at aps.anl.gov> · Fri, 12 Mar 2021 10:10:02 -0600

On 03/12, Ralph Lange via Core-talk wrote:
> I did not expect backward compatibility breaking code changes in a minor
> release.
> Can someone please clarify for me what changes are accepted for which level
> of release jump?!

Any change could be accepted for any release according to

  https://epics.anl.gov/tech-talk/2020/msg00072.php

Andrew makes it clear that EPICS does not follow Semantic Versioning, so
there is no concept of a "minor release" nor a "level of release jump"
having any particular meaning.

In terms of ABI backward compatibility, Andrew said that the project
makes no guarantee whatsoever of ABI backward compatibility even across
the least significant component of the version number.

In terms of API backward compatibility, Andrew said that the project is
aware of the pain that an API breaking change causes, but that there is
no guarantee that the project won't make such a change.  He does say,
however, that if an API breaking change is made,

  We document that and show module developers how to change their code
  so it can be compiled against both the old and new APIs.  If we do
  make an API change, code using the old API that needs to be modified
  should always break at compile-time, we don't want our users to find
  out they need to change their code after an upgrade when something
  doesn't work at 2am.

So, in this case where interfaces have been removed, it seems that the
API breaking change was not documented according to what Andrew said
above since there's nothing in the change documentation explaining how
to change your code to work with the new API.

Lewis

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System