Thomas, I want to experiment with this, pls, could you give me some advise
what are the classes I have to look at?

On Sun, Feb 14, 2016 at 12:00 PM, Thomas Broyer <[email protected]> wrote:

> Just to make it clearer, my suggestion is:
>
>  * force sourceLevel to 8 (either make the argument a no-op –using 8 even
> if arg says 7–, or fail on "-sourceLevel 7")
>  * build GWT with JDK 7; particularly the release artifacts (snapshots
> matter less). Note that this means changing the CI builds to run tests in
> prod mode rather than dev mode, this is probably a good idea anyway given
> we recently changed GWTTestCase to use prod mode by default.
>
> We can revise those rules after 2.8.
>
>
> On Saturday, February 13, 2016 at 6:06:24 PM UTC+1, Manuel Carrasco Moñino
> wrote:
>>
>> Hi all, in the behave of gwt-maintainers, I'm forwarding this discussion
>> started in the maintainer list to the contributors one. Feel free to
>> contribute with your opinions.
>> Basically the matter is about the convenience of not breaking java7
>> compatibility in 2.8
>>
>> Thanks
>>  -Manolo
>>
>> On Fri, Feb 12, 2016 at 6:14 PM, Thomas Broyer <[email protected]>
>> wrote:
>>
>>> FWIW, I just tried the latest snapshot (from today) with Java 7 and it
>>> seems to work (for now; see below).
>>> I think the issue in the samples is with -sourceLevel: the POMs there
>>> set maven.compiler.source to 1.7, which automatically passes -sourceLevel
>>> 1.7 to GWT, which then fails to parse the emul.
>>>
>>> I think that:
>>>  * now that we no longer run tests in "dev mode", it shouldn't be a
>>> problem using -sourceLevel 8 with a JDK 7 (it's a problem in dev mode as
>>> dev mode will compile sources to classes –using JDT so with the
>>> -sourceLevel compat– and then won't be able to read them back in a JDK 7;
>>> IIRC)
>>>  * we should then be able to *build* GWT with a JDK 7, and ensure
>>> compatibility of gwt-servlet with Java 7 runtimes.
>>>  * we could make GWT ignore "-sourceLevel 7" (automatically upgrading to
>>> "8", or simply removing -sourceLevel processing entirely and hard-coding
>>> the value as in older versions of GWT)
>>> This only holds as long as we don't use Java 8 language features and
>>> APIs in GWT proper (and non-GWT tests), but maybe we could set it as a goal
>>> for 2.8?
>>>
>>> Note: I said above that it works "for now", because if we build with JDK
>>> 8, we can never be sure that it'll run with a JDK 7, unless we correctly
>>> cross-compile, by passing the bootclasspath to a JDK 7 too (which is
>>> equivalent to use a JDK 7, except you're using a different version of JavaC
>>> that has a different set of bugs ;-) ) Hence my suggestion above to *build*
>>> the final SDK with a JDK 7.
>>>
>>> Let's continue that discussion publicly on gwt-contrib though.
>>>
>>> On Fri, Feb 12, 2016 at 5:28 PM 'Daniel Kurka' via gwt-maintainers <
>>> [email protected]> wrote:
>>>
>>>> GWT 2.8 needs to contain Java8 APIs so taht guava will start working
>>>> again. All the outstanding Java8 patches need to go in before 2.8. So 2.8
>>>> will not work with Java7.
>>>>
>>>>
>>>> On Fri, Feb 12, 2016 at 5:25 PM Jens Nehlmeier <
>>>> [email protected]> wrote:
>>>>
>>>>> Its not just about adding new classes but we also add APIs to existing
>>>>> classes that require Java8 classes in their signature. So you would
>>>>> need to ignore these changes on method level.
>>>>>
>>>>> AFAICT it was said that as soon as Java 8 APIs are committed GWT will
>>>>> require Java8. If someone needs Java7 support they need to replace the
>>>>> emulation code of GWT 2.8 with the one of GWT 2.7. Because of this
>>>>> possibility we don't use Java8 APIs in gwt-user code. gwt-servlet.jar
>>>>> is something to think about as soon as we want to add GWT-RPC
>>>>> serializer for Java 8 classes. If we really want to give users the
>>>>> possibility to compile GWT 2.8 with Java 7 after replacing the
>>>>> emulation code we probably need a build target that builds
>>>>> gwt-servlet-jdk8.jar when running Java8 only.
>>>>>
>>>>> Generally I thought Java8 stuff will be committed after GWT 2.8 has
>>>>> been released so that GWT 2.8 stays Java7 compatible. I don't know
>>>>> about the Guava issue that requires GWT 2.8 to already have Java8 APIs
>>>>> available. I thought Guava will just release Guava 20 when 2.8 is
>>>>> released because Gauva 19 did use some private APIs of GWT that do not
>>>>> exist anymore.
>>>>
>>>>
>>>>> 2016-02-12 16:06 GMT+01:00 Daniel Kurka <[email protected]>:
>>>>> > +Colin Alworth  +Jens
>>>>> >
>>>>> > Colin and Jens have been doing a lot of the Java8 API work, I
>>>>> believe this
>>>>> > will touch many classes within the JRE and thus will not be as easy
>>>>> as
>>>>> > ignoring a few classes.
>>>>> >
>>>>> > To be clear:
>>>>> > We won't be putting any resources into addressing this since its not
>>>>> an
>>>>> > issue for us, if someone feels strongly (s)he can step up and tackle
>>>>> this,
>>>>> > but the whole case does not seem to be convincing for me, why would
>>>>> agencies
>>>>> > that are slow to adopt things adopt the latest GWT version?
>>>>> >
>>>>> > -Daniel
>>>>> >
>>>>> > On Fri, Feb 12, 2016 at 3:52 PM Manuel Carrasco Moñino <
>>>>> [email protected]>
>>>>> > wrote:
>>>>> >>
>>>>> >> Well the situation I know, is that there are many big companies and
>>>>> >> government agencies moving very slow, their standard server
>>>>> configuration is
>>>>> >> java7, as well as their code standards.
>>>>> >>
>>>>> >> Their GWT projects are compiled in one phase (not client and server
>>>>> >> sides). It could be very difficult for them to compile their byte
>>>>> code for
>>>>> >> 1.7.
>>>>> >> It's true that if they don't use java 8 many features in 2.8 are
>>>>> useless
>>>>> >> for them, but we have to facilitate and encourage users to be in
>>>>> latest
>>>>> >> version.
>>>>> >>
>>>>> >> I don't know how complex it could be, but if for example, ignoring
>>>>> java8
>>>>> >> /emul/ classes could fix the problem I think it's worth to consider.
>>>>> >>
>>>>> >> On Fri, Feb 12, 2016 at 3:42 PM, 'Daniel Kurka' via gwt-maintainers
>>>>> >> <[email protected]> wrote:
>>>>> >>>
>>>>> >>> I am not sure how this is connected to the beta1 release. Beta1
>>>>> did not
>>>>> >>> have any Java8 apis for the final release we need them to support
>>>>> the next
>>>>> >>> version of guava.
>>>>> >>>
>>>>> >>> If you feel strongly you can always step in with a design that will
>>>>> >>> support both modes and execute on it, but we went over this in the
>>>>> SC and
>>>>> >>> this seems like a lot of work for something that almost all devs
>>>>> are fine
>>>>> >>> with (run java8 while developing).
>>>>> >>>
>>>>> >>>
>>>>> >>> On Fri, Feb 12, 2016 at 3:36 PM Manuel Carrasco Moñino
>>>>> >>> <[email protected]> wrote:
>>>>> >>>>
>>>>> >>>> Since beta1 supports 1.7, isn't feasible someway to make the
>>>>> compiler
>>>>> >>>> ignore java8 specific stuff when compiler level is set to java 7?
>>>>> >>>>
>>>>> >>>> On Fri, Feb 12, 2016 at 3:29 PM, 'Daniel Kurka' via
>>>>> gwt-maintainers
>>>>> >>>> <[email protected]> wrote:
>>>>> >>>>>
>>>>> >>>>> Compiling GWT code will require Java 8, if someone is willing to
>>>>> put in
>>>>> >>>>> the work we can potentially make GWT servlet run in java7
>>>>> >>>>>
>>>>> >>>>>
>>>>> >>>>> On Fri, Feb 12, 2016, 3:18 PM Manuel Carrasco Moñino
>>>>> >>>>> <[email protected]> wrote:
>>>>> >>>>>>
>>>>> >>>>>> Is it planed to be fixed? or do we break 1.7 compatibility ?
>>>>> >>>>>>
>>>>> >>>>>> On Fri, Feb 12, 2016 at 3:16 PM, 'Daniel Kurka' via
>>>>> gwt-maintainers
>>>>> >>>>>> <[email protected]> wrote:
>>>>> >>>>>>>
>>>>> >>>>>>> This is expected since java8 emulation patches have gone in.
>>>>> >>>>>>>
>>>>> >>>>>>> On Fri, Feb 12, 2016 at 3:11 PM Manuel Carrasco Moñino
>>>>> >>>>>>> <[email protected]> wrote:
>>>>> >>>>>>>>
>>>>> >>>>>>>>
>>>>> >>>>>>>>
>>>>> >>>>>>>> Current master seems not supporting correctly compilation in
>>>>> java ,
>>>>> >>>>>>>> take a look to CI output when compiling dynatablerf which is
>>>>> configured to
>>>>> >>>>>>>> be compiled in 1.7 mode
>>>>> >>>>>>>>
>>>>> >>>>>>>> http://build.gwtproject.org/job/gwt-samples/15/console
>>>>> >>>>>>>>
>>>>> >>>>>>>>
>>>>>
>>>>
>> --
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