JDK 12 RFR of JDK-802856: Remove javac support for 6/1.6 source and target values

[Stephen Colebourne]

While sad to see Java 6 go, I think JDK 12 is the right time, so +1
for the basic idea of the change here.
thanks
Stephen

On 8 July 2018 at 18:01, joe darcy <joe.darcy at oracle.com> wrote:
> Hello,
>
> Please review the initial implementation of
>
>     JDK-802856: Remove javac support for 6/1.6 source and target values
>     http://cr.openjdk.java.net/~darcy/8028563.4/
>
> and the accompanying CSR:
>
>     https://bugs.openjdk.java.net/browse/JDK-8206877
>
> I suspect at least one adjustment of the changeset will be needed, as
> discussed below.
>
> All the langtools tests pass with these changes.
>
> A few comments about the current state of the patch:
>
> Updating the various components of the compiler was in part revisiting and
> then retiring some of the detailed engineering done for Project Coin, such
> as giving distinct error messages about a try statement lacking other pieces
> dependent on whether or not try-with-resources is supported under the source
> version in effect.
>
> The refactoring in Source.java to use the Feature enum was easy to work
> with. Excising the now conceptually dead code and checks was
> straightforward. The enum constant for DIAMOND was *not* removed, although
> it is also semantically unconditionally true now just like the other
> introduced-in-7 features, because messages about diamond from
> checkSourceLevel called in the parser are used in the testing  of
> diagnostics generated for the preview feature functionality. I didn't dig
> down to try to determine the full set of interactions here. There is also
> support for the diamond finder elsewhere in the compiler. I think it would
> be acceptable to leave DIAMOND available as a enum constant if there are
> other uses for it.
>
> While an earlier changeset cleared out uses of -source 6 and -target 6
> (JDK-8206439), various other tests needed updating since -source 7 is now
> obsolete. This was often handled by adding "-lint:-options" to the compile
> invocation. I'll file a follow-up issue to add "-lint:-options" to a handful
> of uses of -source 8 to avoid similar edits being needed in the future.
>
> For expediency, I ignored the warning in make/data/symbols/symbols that
> "THIS FILE IS AUTOMATICALLY GENERATED. DO NOT EDIT." and edited the file to
> remove support for --release 6. This aspect of the change should be redone
> properly, but I thought it would be quicker to ask about this point during
> the code review than investigate how this aspect of the build works. Once
> the proper way is determined, I'll send a note to build-dev for a review of
> that aspect of the change.
>
> Thanks,
>
> -Joe
>
>