Problems building with --release=8

Jonathan Gibbons jonathan.gibbons at
Wed Jan 17 17:43:15 UTC 2018

On 1/17/18 9:37 AM, David Lloyd wrote:

> I'm trying to create some MR JARs for projects which use
> sun.misc.Unsafe and sun.reflect.ReflectionFactory (both of which exist
> in the jdk.unsupported module).  For the Java 8 portion, I'm
> attempting to move from using the Java 8 javac to Java 9 (or later).
> However I'm running into a problem where these classes are not
> available when I compile with --release=8.
> As a workaround, I created a JAR which stubbed these two classes and
> included it on the compile class path.  However, it seems that they
> were actively filtered out or ignored somehow.  Removing --release=8
> and just using -source 8 -target 8 allowed the compilation to succeed,
> however I want to be sure that no 9+ classes sneak into the 8 part so
> I want to use --release=8 if possible.
> If jdk.unsupported is allowed for Java 9+, then surely these two
> classes should be included in the Java 8 image.
> Did I make some kind of mistake or is this a legitimate bug?

It doesn't sound like you made a mistake, but this is not a bug.
Generally, the spec for --release N is to provide access to the
public documented API for JDK N.

That being said, there has been discussion recently about providing
access to some of the API that precedes jdk.unsupported, as a special

-- Jon

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