RFR: 8301220: Return value of toArray() of Сollection types from java.base should be trusted [v2]

[j3graham]

On Fri, 27 Jan 2023 13:53:45 GMT, Glavo <duke at openjdk.org> wrote:

>> I checked the `java.base` module, and all the `Collection#toArray()` method of collections be implemented correctly.
>> 
>> Their return values can be trusted, so many unnecessary array duplication can be eliminated.
>
> Glavo has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Collections.isTrustedCollection

What about creating a public `Collections.toArray(Collection c)` method that would return `c.toArray` for trusted collections, otherwise return a copy? This would allow any code to get a trustable array, while avoiding the copy when possible.

Even if this method was packaged-scoped, it might be a more concise way to access this capability in most cases.

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PR: https://git.openjdk.org/jdk/pull/12212