JMC-6513: Wrong version of compiled classes when importing JMC maven projects in Eclipse with JDT Default Compiler Level of 11

[Langer, Christoph]

Hi Marcus,

thanks for your comments. I agree - it would be ideal if everything was maintained via Maven and all Eclipse settings would be handled by this.

Maybe, if I find time, I'll dig deeper in this. Especially why the behavior is so different between Mac and Windows.

However, for the time being, I'd appreciate if this can be pushed.

Cheers,
Christoph

> -----Original Message-----
> From: Marcus Hirt <marcus.hirt at datadoghq.com>
> Sent: Freitag, 28. Juni 2019 22:45
> To: Langer, Christoph <christoph.langer at sap.com>; Guru
> <guru.hb at oracle.com>
> Cc: jmc-dev at openjdk.java.net
> Subject: Re: JMC-6513: Wrong version of compiled classes when importing
> JMC maven projects in Eclipse with JDT Default Compiler Level of 11
> 
> Hi Christoph,
> 
> I agree; I see no harm in taking this patch, though I would love to
> see Maven and Eclipse collaborate better. In the best of all worlds,
> no Eclipse project files would be required, Maven would be the one
> source of truth and a simple Maven import would be all that is
> required. Guru, do you have any strong opinion here?
> 
> Kind regards,
> Marcus
> 
> On Fri, Jun 28, 2019 at 9:58 PM Langer, Christoph
> <christoph.langer at sap.com> wrote:
> >
> > Ping: Any comments for this?
> >
> >
> >
> > From: Langer, Christoph
> > Sent: Donnerstag, 20. Juni 2019 23:56
> > To: jmc-dev at openjdk.java.net
> > Subject: JMC-6513: Wrong version of compiled classes when importing JMC
> maven projects in Eclipse with JDT Default Compiler Level of 11
> >
> >
> >
> > Hi,
> >
> >
> >
> > please let me know what you think of this patch:
> >
> >
> >
> > Bug: https://bugs.openjdk.java.net/browse/JMC-6513
> >
> > Webrev: http://cr.openjdk.java.net/~clanger/webrevs/JMC-6513.0/
> >
> >
> >
> > I'm having issues when importing the jmc projects into my Eclipse which
> has a default JDK compiler level of 11. Although the JMC projects define a
> JSE18 in their .classpath files, the classes get compiled with Java 11 version.
> This can be helped by creating ".settings/org.eclipse.jdt.core.prefs" files
> which set the compiler to 1.8. Then these issues were gone. So, in my patch I
> propose to add them. A Java compiler level of 8 is needed in Eclipse because I
> want to be able to run/debug with any JDK down to 8.
> >
> >
> >
> > Something is a bit weird though with maven import. On my Windows
> Eclipse I observe that the import would generate these
> .settings/org.eclipse.jdt.core.prefs as contained in the patch. However, this
> import also regenerates some .classpath files which brings other issues and is
> not what is wanted. On my Eclipse on Mac, I don't see neither
> .settings/org.eclipse.jdt.core.prefs getting generated nor .classpath files
> rewritten. Maven settings in both Eclipse installations seem to be the same.
> Does anybody have an explanation for that?
> >
> >
> >
> > So, AFAICS, I don't think my patch causes any harm and can safely be used.
> There's also precedence for that such as the projects in jmc/core (which
> compile with JDK 1.7), as well as project
> jmc/application/org.openjdk.jmc.osgi.extension which was introduced by
> the patch for JMC-5859 [1].
> >
> >
> >
> > Thanks
> >
> > Christoph
> >
> >
> >
> > [1] http://hg.openjdk.java.net/jmc/jmc/rev/2cc768144a86
> >
> >
> >