Backport "Mix in the productPrefix hash statically in case class hashCode" to 3.3 LTS
#345
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Since 2.13, case class `hashCode` mixes in the hash code of the `productPrefix` string. This is inconsistent with the `equals` method, subclasses of case classes that override `productPrefix` compare equal but have a different `hashCode`. This commit changes `hashCode` to mix in the `productPrefix.hashCode` statically instead of invoking `productPrefix` at runtime. For case classes without primitive fields, the synthetic `hashCode` invokes `ScalaRunTime._hashCode`, which mixes in the result of `productPrefix`. To fix that, the synthetic hashCode is changed to invoke `MurmurHash3.productHash` directly and mix in the name to the seed statically.
Since 2.13, case class `hashCode` mixes in the hash code of the `productPrefix` string. This is inconsistent with the `equals` method, subclasses of case classes that override `productPrefix` compare equal but have a different `hashCode`. This commit changes `hashCode` to mix in the `productPrefix.hashCode` statically instead of invoking `productPrefix` at runtime. For case classes without primitive fields, the synthetic `hashCode` invokes `ScalaRunTime._hashCode`, which mixes in the result of `productPrefix`. To fix that, the synthetic hashCode is changed to invoke `MurmurHash3.productHash` directly and mix in the name to the seed statically. [Cherry-picked d2fc358][modified]
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No regressions detected in the community build up to backport-lts-3.3-22957. |
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Backports scala#22865 to the 3.3.7.
PR submitted by the release tooling.
[skip ci]