[lworld] RFR: 8294312: [lworld] Add java.util.Objects.isIdentityObject

[Mandy Chung]

On Wed, 28 Sep 2022 15:49:05 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

> Add `java.util.Objects.isIdentityObject(obj)` and update tests.
> 
> Correct j.l.Class.isIdentity() and .isValue() to correctly identify all arrays as identity objects.
> (The modifiers for array classes do have not reliable ACC_IDENTITY or ACC_VALUE bits).
> 
> Updated ValhallaFeaturesTest to use junit.

src/java.base/share/classes/java/util/Objects.java line 201:

> 199:         return o.getClass().isIdentity() ||
> 200:                 o.getClass() == Object.class ||
> 201:                 !ValhallaFeatures.isEnabled(); // Before Valhalla all objects are identity objects.

`Class::isIdentity` should check for `!ValhallaFeatures.isEnabled()` as well.   Just a side note: we will need to go through the current implementation to see where this check is needed as well.

test/jdk/valhalla/valuetypes/ObjectMethods.java line 85:

> 83:                 {new PrimitiveRecord(1, "A"), false},
> 84:                 {new ValueRecord(1,"B"), false},
> 85:                 {new int[0], true},  // arrays of primitives classes are identity objects

s/primitives/primitive/

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PR: https://git.openjdk.org/valhalla/pull/770