On Tue, 28 May 2024 19:13:50 GMT, Jorn Vernee <jver...@openjdk.org> wrote:
>> Pavel Rappo has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Fix incorrect utf16 hashCode adaptation
>
> 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.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/19414#discussion_r1618835934
