On Tue, Dec 15, 2020 at 11:39 AM Jiri Vanek <jvanek(a)redhat.com> wrote:
Hi! Mikolaj!
On 12/15/20 11:08 AM, Mikolaj Izdebski wrote:
> On Mon, Dec 7, 2020 at 11:26 AM Jiri Vanek <jvanek(a)redhat.com> wrote:
>> The idea is, to provide rpm macros, keeping the default source/target eventually
- for jdk11 and up -the release - numbers for javac to use.
>> Then to provide tooling, which will help packagers to use them - for ant and
maven it should be simple. For others, probably nothing to do on our side, each packager
will be able to patch/sed theirs builds as necessary (Still it will help a lot for
future).
>
> You seem to be implying that there should be a distro-wide default for
Correct
And do you propose to always override these values set by upstreams
with distro-specific values, or provide defaults only in case
upstreams don't set explicit source/release/target?
> source/target/release values. What values do you propose to set
them
> to? 11?
No, 8.
So even if upstream builds with --source 11 --target 11, in Fedora you
want to override their decision and build the software with --source 8
--target 8 ?
Once we move to jdk17 as system JDK, the value will be enforced to
rise to 11.
>
> Historically we always tried to stay close to upstream and follow
> their choices for source/target/release whenever possible, changing
There is no upstream of source/target/release. Javac always by default compile for its
current version. javac8 would default to source/target of 8, java11 to 11 and so on.
The usptream we can speak about, is oldest supported version of javac. Now, for jdk 11
it is 6. For jdk17 it will be 11. So in this, we are keeping perfectly aligned with
uptream. And there is absolutey no wish to bend this (eg patch javac of jdk17 to eat
source/target 8)
What I meant is that most of upstream projects do pass source/target
to javac. Projects built with Maven always do that. For upstreams that
don't set these values I consider this as a bug and try to contact
them to fix the issue.
> them only when necessary. A common case was upstreams targeting
very
> old Java releases that are no longer supported by current Java
> compilers. Therefore IMHO it makes most sense to force *minimal*
Right, the limit was set to 5 versions to past.
On contrary, i think it have snese to have default od oldest supported.
New projects usually built on older libreries. And it is library set where this change is
primarily targetting. If old library is built by old source/target, is still usbale by
newer source/target project and remains usable for older projects too.
Anyway toolchain shold be aware of %_javac_source, %_javac_target, and %_javac_release
being %nil, and default to defaults in that state.
Maybe I don't understand what these macros are supposed to mean
exactly. Can you explain what you mean by them?
> source/target/release values, or change combinations that are known
> not to work for sure. But overriding these values across the whole
> distro is not a good idea in my opinion only, it only introduces
> unnecessary deviation from upstreams, and potentially introduces bugs.
Maybe. Although I doubt it a lot. The release switch is much more tricky one. But is only
9+. So for source/target of 8 we do not need to worry about it.
During bump of system jdk to jd11 pretty common use-case raised - where we tried to
compile all by defaults, then all was suddenly source/target 11. So all packages, wihch
have to remain on jdk8 (less then 10%) suddenly couldnot use theirs dependencies and so
they rebuilt depndencies with source/target 8 anyway, or used embedded ones or created
comapct legacy pakcages. From those three, the first is smallest evil.
I think that upstream projects not setting explicit
source/target/release should be fixed individually, fixes should be
forwarded upstream.
So compiling with oldest possible source/target still seems to be
rigt to me.
I disagree. Most projects won't build if you set source/target to
values lower than upstream. Besides that there are cases in which
newer bytecode introduces very significant performance gains (one
example I remember is the use of Invokedynamic in Groovy). Compiling
for older releases would introduce performance regressions when
compared to upstream builds.
>
> --
> Mikolaj Izdebski
Tahxn a lot!
>
>> I do not know how to provide them as default (except hardcoding in xmvn, and
only allow to disable them on demand).
>>
>> This will smooth the bump to jdk17 in f36 really a lot.
>>
>>
>> Thoughts?
>> J.
>> --
>> Jiri Vanek
>> Senior QE engineer, OpenJDK QE lead, Mgr.
>> Red Hat Czech
>> jvanek(a)redhat.com M: +420775390109
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--
Jiri Vanek
Senior QE engineer, OpenJDK QE lead, Mgr.
Red Hat Czech
jvanek(a)redhat.com M: +420775390109