RFR: 8254274: Development to add 'lint' warning for @ValueBased classes

[Srikanth Adayapalam]

On Mon, 26 Oct 2020 17:11:55 GMT, Dan Smith <dlsmith at openjdk.org> wrote:

>> A few questions for reviewers:
>> 
>> (1) Do we want the lint mode to be on my default ? Presently it is off and has to be expressly opted into.
>> (2) Do we want to not use up a bit for VALUE_BASED flag and simply walk the annotations to determine if a type is value based ??
>
>> (1) Do we want the lint mode to be on my default ? Presently it is off and has to be expressly opted into.
> 
> Given that it's already been established that there's an ad hoc set of on-by-default lint warnings, yeah, I think this one makes sense to put in that set. (Inventing a new concept of on-by-default lint warnings is something I'd be more hesitant about.)

I have pushed additional changes to incorporate review comments:

    - The lint mode's token is "synchronization" (instead of "synchronize")
    - This lint mode is on by default
    - Redundant warnings on wait/notify calls are removed.
    - We don't burn up a flag bit to mark value based classes. We simply walk the declaration annotations on a class to discover the ones that are @ValueBased
    - Ensure descriptions (in the neighbourhood) in javac.properties end with a period for consistency's sake. 
    - Streamline and simplify tests.

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PR: https://git.openjdk.java.net/valhalla/pull/237