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Diffstat (limited to 'test/files/neg/t7872b.scala')
-rw-r--r-- | test/files/neg/t7872b.scala | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/test/files/neg/t7872b.scala b/test/files/neg/t7872b.scala new file mode 100644 index 0000000000..307a1470c5 --- /dev/null +++ b/test/files/neg/t7872b.scala @@ -0,0 +1,23 @@ +object coinv { + def up[F[+_]](fa: F[String]): F[Object] = fa + def down[F[-_]](fa: F[Object]): F[String] = fa + + up(List("hi")) + + // should not compile; `l' is unsound + def oops1 = down[({type l[-a] = List[a]})#l](List('whatever: Object)).head + "oops" + // scala> oops1 + // java.lang.ClassCastException: scala.Symbol cannot be cast to java.lang.String + // at com.nocandysw.coinv$.oops1(coinv.scala:12) + + type Stringer[-A] = A => String + down[Stringer](_.toString) + // [error] type A is contravariant, but type _ is declared covariant + // up[Stringer]("printed: " + _) + + // should not compile; `l' is unsound + def oops2 = up[({type l[+a] = Stringer[a]})#l]("printed: " + _) + // scala> oops2(Some(33)) + // java.lang.ClassCastException: scala.Some cannot be cast to java.lang.String + // at com.nocandysw.coinv$$anonfun$oops2$1.apply(coinv.scala:20) +} |