RFR: 8299444 java.util.Set.copyOf allocates needlessly for empty input collections [v2]

[Viktor Klang]

On Sun, 22 Jan 2023 15:20:18 GMT, Attila Szegedi <attila at openjdk.org> wrote:

>> Viktor Klang has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - 8299444: java.util.Set.copyOf allocates needlessly for empty input collections
>>    
>>        Modifies ImmutableCollections.listCopy:
>>        Introduces a check for isEmpty to avoid allocation in the case of an empty input collection.
>>  - 8299444: java.util.Set.copyOf allocates needlessly for empty input collections
>>    
>>    Modifies Map.copyOf:
>>    Introduces a check for isEmpty to avoid allocation in the case of an empty input Map.
>
> src/java.base/share/classes/java/util/ImmutableCollections.java line 174:
> 
>> 172:             return List.of();
>> 173:         } else {
>> 174:             return (List<E>)List.of(coll.toArray()); // implicit nullcheck of coll
> 
> The comment is no longer relevant here, as it now happens on line 171.

@szegedi Nice catch, Attila. Corrected!

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PR: https://git.openjdk.org/jdk/pull/11847