Fix #2973: Check variances of class parents #4932
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smarter
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Aug 12, 2018
| case _ => defn.ObjectType // can happen if class files are missing | ||
| } | ||
| } | ||
| tp.parents.map { p => transformedParent(apply(p)) } |
tests/neg/i2973.scala
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| @@ -0,0 +1,2 @@ | |||
| class Foo[U] | |||
| class Bar[-T] extends Foo[T] // error: contravariant type T occurs in invariant position | |||
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More testcases (related to annotations, etc) would be nice.
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Can't find any annotation for parent classes apart from @uncheckedVariance. So added more tests for that.
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You can just create a dummy annotation and use it wherever
In particular, this preserves @uncheckedVariance for the variance checker.
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Fix #2973: check variance of parent classes via
ClassInfo.classParents(via @odersky's fix in #4057).To account for
@uncheckedVariance(unlike #4057), preventNamerfrom stripping annotations inclassParents. Surprisingly, the rest of Dotty doesn't mind!We probably should test this on the new collections and the community build, since collections will stress this out much more.