[fedora-java] Eclipse Luna on Fedora 21 and JDK 8 requirement
Deepak Bhole
dbhole at redhat.com
Fri Oct 31 18:30:53 UTC 2014
* Christopher <ctubbsii-fedora at apache.org> [2014-10-31 14:02]:
> On Fri, Oct 31, 2014 at 11:43 AM, Deepak Bhole <dbhole at redhat.com> wrote:
>
> * Christopher <ctubbsii-fedora at apache.org> [2014-10-31 11:37]:
> > On Fri, Oct 31, 2014 at 5:35 AM, Mat Booth <fedora at matbooth.co.uk> wrote:
> >
> > On 31 October 2014 08:18, Max Rydahl Andersen <manderse at redhat.com>
> wrote:
> >
> >
> > Fedora 20 used to have 3 different Java versions (5,
> 7, 8).
> >
> >
> > ok, why no Java 6 ?
> >
> >
> > Besides many technical reason the biggest one is
> non-technical in
> > my eyes - no one volunteered to do it. You know it's always a
> > matter of "who will do the work?". I'm pretty sure that if
> someone
> > jumps in and say "Hey, I'll maintain Java 6, fix problems/
> adopt
> > Java 6 to changes in the OS if neeeded, help strengthen the
> > switching between JREs, go through the Java projects(shipped
> in
> > Fedora) and help them properly set their targets in build
> scripts
> > so builds properly work on Java 6 and etc" there will be no
> > objection to having Java 6. :)
> >
> >
> > Fair enough.
> >
> >
> > OpenJDK 7
> > was removed from F21 because its support will end
> before
> > F21 EOL and
> > we
> > don't want to ship software not supported by
> upstream.
> >
> >
> > So for users most stable thing is to use Oracle JDK
> builds
> > instead which
> > are and will stay available ?
> >
> >
> > Users can still try to use it but it's something that they
> have to
> > do on their own - download, extract, set PATH, etc. Just like
> on
> > every platform with Oracle JVM.
> >
> >
> > Yeah, this is similar experience for developers on all other
> platforms
> > so its expected/assumed.
> >
> >
> > No separate repo with "binaries that is currently
> supported but
> > will not
> > stay supported for all of fedora 21 lifetime" ?
> >
> >
> > 1. Fedora can not legally redistribute Oracle JDK.
> >
> >
> > I know - hence why I would think having a openjdk 7 build would
> make
> > sense.
> >
> >
> > 2. Fedora can not distribute something that Fedora developers
> can
> > not support if there is a problem in it (as it is with Oracle
> JDK).
> >
> >
> > so *any* package that is known to be marked as EOL sometime in
> the
> > future before the upcoming Fedora EOL's gets removed from that
> future
> > Fedora release ? Even that Java 7 is still the most used and
> targeted
> > Java version ?
> >
> >
> >
> > Maybe I misunderstand the use-case, but your projects can still
> target Java
> > 7 even if Eclipse is running on Java 8.
> >
> >
> >
> > That's not entirely true. This only works if a true JDK7 exists on the
> system.
> > While newer JDKs are able to target older runtimes, there are cases where
> one
> > can introduce source-incompatible changes that work in a newer JDK, but
> not in
> > an older JDK. This matters for collaborating on projects where some team
> > members are not using the newer JDK to target the older runtime. For
> instance,
> > this happened with JDK7/JDK6 on my team... JDK7 allows certain use of
> generics
> > syntax that properly compiles to JDK6 target, and validates in Eclipse as
> JDK6
> > source-compatible, but the actual JDK6 compiler treats as an error. I had
> to
> > abandon my use of Fedora 20 as a development environment for our project,
> and
> > revert to CentOS6 in order to guarantee I wasn't introducing source that
> was
> > incompatible with JDK6. Not making older JDKs (even stale ones) available
> is
> > likely to discourage Java developers from using Fedora as a development
> > platform.
> >
>
> This is a bug -- did you file it with us? If so, what was the
> conclusion? If -target 1.6 was specified, it should have been able to
> run it on 6 without issues and any problems encountered are certainly
> bugs.
>
>
>
> There is no issue with -target 1.6; the issue was with strict source
> compatibility with 1.6. I can't recall the specifics (it had something to do
> with generic type checking, because 1.7's javac can make better inferences),
> but that's outside the scope of this issue. The main point, as it relates here,
> is that there may not be strict compatibility between javac provided by
> different JDKs, even if javac makes a best effort attempt to parse older
> source. A more obvious problem is the lack of bootstrap classpaths for older
> -source/-target, which is known to be likely to create compiled code that is
> not capable of running in an older JVM (this doesn't matter if you're
> developing for the latest Fedora, but it matters if you're using the latest
> Fedora to develop for other platforms, like RHEL or Android).
>
Ah, yeah not much we can do (with current setup) where the older rt.jar
is needed on bootstrap path :/
Deepak
>
> Deepak
>
> > Personally, unlike the original poster, I don't care which JVM Eclipse is
> > running on, itself (OpenJDK 8, or whatever is latest, works for me). But,
> I do
> > care about which JDKs are available on the system that Eclipse can launch
> to
> > build projects, because that affects whether I can use Fedora as my
> development
> > platform on team projects where some team members are using older JDKs
> (which
> > should be fine, until the project bumps its minimum JVM dependency).
> >
>
> > --
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> > java-devel at lists.fedoraproject.org
> > https://admin.fedoraproject.org/mailman/listinfo/java-devel
>
>
>
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