On Wed, 29 May 2024 12:53:42 GMT, Pavel Rappo <pra...@openjdk.org> wrote:
>> src/java.base/share/classes/jdk/internal/util/ArraysSupport.java line 252:
>>
>>> 250: return switch (length) {
>>> 251: case 0 -> initialValue;
>>> 252: case 1 -> 31 * initialValue + (int) a[fromIndex];
>>
>> Suggestion:
>>
>> case 1 -> 31 * initialValue + (int) a[fromIndex]; // sign
>> extension
>
> To be honest, I don't think that this cast is needed. A better solution than
> to add a comment would be to delete all `(int)` casts from new `hashCode*`
> methods of `ArraysSupport`.
>
> Those `(int)` casts migrated from `hashCode` methods of `Arrays` where there
> were used if neither of two `+` operands were of type `int`. But in
> `ArraysSupport` it's no longer the case: `31 * initialValue` is always `int`
> because `initialValue` is. So, `a[fromIndex]` is promoted to `int` by the
> virtue of
> https://docs.oracle.com/javase/specs/jls/se22/html/jls-5.html#jls-5.6.
>
> For more confidence, consider that the `private static int hashCode` methods
> (implementation) of `ArraysSupport` do not have those casts.
Removed casts in
https://github.com/openjdk/jdk/pull/19414/commits/d8dabc68c4264520fd6c57c949049f2ab5c8e0ec.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/19414#discussion_r1619127224
