Problems with non Oracle boot JDKs and class file version 52

[David Holmes]

On 7/12/2012 8:31 PM, Erik Joelsson wrote:
> How is configure picking up a jdk6?

AFAIK it was the Java found first in the path.

> I'm not able to reproduce this for lack of access to an icedtea jdk7

No Ubuntu systems? You can use bussund0416.us.oracle.com

> installation. Any chance a "LOG=debug JOBS=1" log could be provided?

Here's the failing command (edited for presentation):

/usr/lib/jvm/java-7-openjdk-amd64/bin/java -Xms64M -Xmx1100M 
-XX:PermSize=32m -XX:MaxPermSize=160m -XX:ThreadStackSize=1536 \
 
-Xbootclasspath/a:/java/embedded/users/dh198349/build-infra/builds/b00/se-linux-i586-ea/jdk/classes 
\
 
"-Xbootclasspath/p:/java/embedded/users/dh198349/build-infra/builds/b00/se-linux-i586-ea/langtools/dist/bootstrap/lib/javac.jar" 
-jar 
/java/embedded/users/dh198349/build-infra/builds/b00/se-linux-i586-ea/langtools/dist/bootstrap/lib/javac.jar 
\
             -XDprocess.packages -proc:only \
             -processor com.sun.tools.javac.sym.CreateSymbols \
 
-Acom.sun.tools.javac.sym.Jar=/java/embedded/users/dh198349/build-infra/builds/b00/se-linux-i586-ea/images/lib/rt.jar 
\
 
-Acom.sun.tools.javac.sym.Dest=/java/embedded/users/dh198349/build-infra/builds/b00/se-linux-i586-ea/images/symbols/META-INF/sym/rt.jar 
\
             java.applet java.awt java.awt.color java.awt.datatransfer 
java.awt.dnd java.awt.event java.awt.font java.awt.geom java.awt.im 
java.awt.im.spi java.awt.image java.awt.image.renderable java.awt.print 
java.beans java.beans.beancontext java.io java.lang
...
com.sun.servicetag com.oracle.net com.oracle.nio
Error occurred during initialization of VM
java/lang/UnsupportedClassVersionError: sun/misc/PostVMInitHook : 
Unsupported major.minor version 52.0

----

Now PostVMInitHook is a class from the closed/Oracle repo. So here is 
what I think is happening - this closed class gets referenced but 
because we are on an OpenJDK build it is not found in rt.jar, but is 
found in our freshly built jdk/classes - hence the jdk7 VM tries to load 
a JDK 8 class and fails.

So it would seem that an OpenJDK VM can not be used to bootstrap the 
Oracle JDK.

Not sure there is anything we can do about that except "don't do that".

David
-----

>
> /Erik
>
> On 2012-12-07 00:35, David Holmes wrote:
>> I've now seen two people encounter problems trying to build Profiles
>> using the new build system, when their boot JDK is the locally
>> installed IcedTea openjdk distribution (7 in one case and 6 in another).
>>
>> The error occurs creating jar files eg
>>
>> Creating resources.jar
>> Error occurred during initialization of VM
>> java/lang/UnsupportedClassVersionError: sun/misc/PostVMInitHook :
>> Unsupported major.minor version 52.0
>>
>> Are we using bootclasspath tricks that only work on Oracle JDK?
>>
>> David
>>