Problems building with --release=8

David Lloyd david.lloyd at
Wed Jan 17 17:49:22 UTC 2018

On Wed, Jan 17, 2018 at 11:43 AM, Jonathan Gibbons
<jonathan.gibbons at> wrote:
> 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.

I'm on board with that, however it is also preventing me from adding
my own sun.misc etc. on the class path.  Surely _that_ is a bug?

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

That would be nice.


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