Fix ActivityArrayMap hashCode() using raw registry ids instead of Activity hashes#800
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Dreeam-qwq merged 1 commit intoJul 4, 2026
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…ivity hashes MapEntry#hashCode() and ActivityArrayMap#hashCode() hashed the raw activity registry id, while the entry key is the Activity itself - getKey() and equals() already use RegistryTypeManager.ACTIVITY_DIRECT[...]. Per the Map/Map.Entry contract an entry's hash is key.hashCode() ^ value.hashCode(), and Activity#hashCode() is name.hashCode(), not the id. As a result an ActivityArrayMap (and its entries) could be equal to an ordinary map with the same contents while returning a different hashCode, breaking the equals/hashCode contract. Hash the Activity instead, matching getKey()/equals().
noramibu
approved these changes
Jul 3, 2026
Contributor
|
This fix looks correct for ActivityArrayMap, but AttributeInstanceArrayMap seems to have the same issue. Maybe a follow-up PR, or dealing with in this PR would be better? |
hayanesuru
approved these changes
Jul 4, 2026
Member
Thanks to your review! We can do it in another PR or commit, it’s fine =w= |
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Problem
ActivityArrayMapstores each key as its raw activity registry id (int), and twohashCode()implementations hash that raw id instead of theActivity:MapEntry#hashCode()returnsObjects.hashCode(key) ^ Objects.hashCode(value)wherekeyis the int id — even though the same class'sgetKey()andequals()use the actualActivityviaRegistryTypeManager.ACTIVITY_DIRECT[key]. So an entry'sequals()andhashCode()disagree.ActivityArrayMap#hashCode()sumsObjects.hashCode(k[i]) ^ ...over the raw ids for the same reason.The
Map/Map.Entrycontract defines an entry hash askey.hashCode() ^ value.hashCode(), and the key here is anActivitywhosehashCode()isname.hashCode(), not its id. Sinceequals()compares against arbitraryActivity-keyed maps, anActivityArrayMap(or its entries) can be equal to an ordinaryHashMapholding the same contents while returning a differenthashCode(), breaking theObjectequals/hashCode contract.Fix
Hash the
Activity(viaRegistryTypeManager.ACTIVITY_DIRECT[...], exactly asgetKey()/equals()already do) instead of the raw id, in bothhashCode()methods.Testing
./gradlew applyAllPatchesand./gradlew :leaf-server:compileJavaboth build cleanly on a JDK 25 toolchain. Docs-level behaviour of a single map is unchanged; its hash is now correct when compared against otherMapimplementations.