Fix handling of Java varargs #8718
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The class constant corresponding to the primitive type `int` is represented in bytecode by `Integer.TYPE`, this is correctly handled when calling `clsOf`, but so far `ElimRepeated` was manually creating a constant instead which does not work (I've now changed the backend to emit a failure instead of doing the wrong thing when someone does that, I also plan to rework the way we handle classOf to make this less error-prone). Note: after this commit, tests/run/t1360.scala started failing, this is fixed in the next commit.
A Java generic array `T[]` is unpickled in ClassfileParser to `Array[T & Object]`, because it will not accept primitive arrays. However, Java varargs were special-cased to drop this intersection. Erasure contained some code to compensate for this, but this is still unsound and lead to tests/run/t1360.scala failing with a ClassCastException. Thanks to scala#8669 we can drop this special-casing of varargs without affecting typing too much: it's still possible to pass `Array(1, 2): _*` where `(T & Object)*` is expected because adaptation will take care of boxing. One test case had to be adapted, I replaced: def apply[X](xs : X*): java.util.List[X] java.util.Arrays.asList(xs: _*) with: def apply[X <: AnyRef](xs : X*): java.util.List[X] = java.util.Arrays.asList(xs: _*) I don't think that's too constraining. Note: after this commit, tests/run/i533 started failing, this is fixed in the next commit.
Treat them like generic arrays coming from Java classfiles: `T[]` needs to be typed as `Array[T & Object]` since it will not accept primitive arrays.
odersky
approved these changes
May 25, 2020
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