JEP 309 (Dynamic Class-File Constants) integration into build 21?

Remi Forax forax at
Sun Jul 8 11:11:33 UTC 2018

Hi Ess,

----- Mail original -----
> De: "Ess Kay" <s.2016.kay at>
> À: "compiler-dev" <compiler-dev at>
> Envoyé: Dimanche 8 Juillet 2018 07:41:27
> Objet: JEP 309 (Dynamic Class-File Constants) integration into build 21?

> Has JEP 309 been integrated into build 21 (2018/7/5)?  I am unable to
> get javac to generate a CONSTANT_Dynamic entry.

the VM recognizes CONSTANT_Dynamic but there is no feature of Java the language that uses CONSTANT_Dynamic yet,
it's like when Java 7 VM has the support of invokedynamic but Java using it only in 8 for creating lambdas.

There are several features that may use CONSTANT_Dynamic, the JEP 303, constant lambdas creation, switch (expression switch or plain old switch on String and Enums), but none of them are currently integrated with the JDK.

> If JEP 309 has not yet been integrated any idea when it will appear in
> the JDK 11 build? Need to be able to generate our own more complicate
> test cases prior to general availability.

You can test using ASM [1] (6.2 and up) or if you are adventurous you can use cplisp [2] which is a lisp that can compile its expression into CONSTANT_Dynamics.



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