RFR: universal type variables: initial prototype [v3]

[Vicente Romero]

On Wed, 11 Aug 2021 14:58:15 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> doing this change right now breaks the build, I think it is because we generate reference projections for universal type vars in a lazy way, so some universal type variables could have its projection field set to null
>
> ugh - I understand - moving forward it'd be nice not to depend on tricky init semantics.

yep, will fix this

>> not sure to be honest, although there is no reference in the JEP to these warnings so we can do either now
>
> I double checked with Brian yesterday - he confirmed that both `T` and `T.ref` should not support identity operation (well, given warning when attempting to).

ok, thanks for double checking, will fix this

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PR: https://git.openjdk.java.net/valhalla/pull/521