Draft JEP: Incubating Language and VM Features (original) (raw)

Alex Buckley alex.buckley at oracle.com
Wed Jan 24 19:27:06 UTC 2018

On 1/24/2018 1:30 AM, Volker Simonis wrote:

Finally, the JEP doesn’t specify if version N may (silently or explicitly) support version N+1’s incubating features. This may be attractive for LTS releases.

If Java SE N had no notion of feature X, and Java SE N+1 introduced X as an incubating feature, then there is no realistic possibility of doing a Maintenance Release of SE N to add an incubating feature X. I don't meant to do this in a "Maintenance Release of SE N". The question was if a Java vendor can do that in his implementation of "Java N" if that implementation still passes the "Java N TCK".

The JEP was careful to avoid vendor issues, and the above is a vendor-specific question, so I am unable to answer it here.

I think most people would agree that taking a final-and-permanent feature in Java SE $N+1 (say, LVTI in Java SE 10) and adding it behind an --incubating flag in an implementation of Java SE $N is very weird. After all, the feature was not listed as incubating in the relevant appendix of the Java SE $N Platform specification. And "Nothing in this JEP should be interpreted as encouraging or allowing fragmentation of the Java SE Platform."

Alex

More information about the jdk-dev mailing list