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object Test
{
def s1 = "bob".toList match { case Seq('b', 'o', 'b') => true } // list ok
// not final, allowed
class Bop
def s2(x: Bop) = x match { case Seq('b', 'o', 'b') => true }
// covariance, allowed
final class Bop4[+T]
def s3[T](x: Bop4[T]) = x match { case Seq('b', 'o', 'b') => true }
// contravariance, allowed
final class Bop5[T, U, -V]
def s4[T1, T2](x: Bop5[_, T1, T2]) = x match { case Seq('b', 'o', 'b') => true }
// free type parameter, allowed
final class Bop3[T]
def f4[T](x: Bop3[T]) = x match { case Seq('b', 'o', 'b') => true }
// String and Array are final/invariant, disallowed
def f1 = "bob".reverse match { case Seq('b', 'o', 'b') => true } // fail
def f2 = "bob".toArray match { case Seq('b', 'o', 'b') => true } // fail
// final, no type parameters, should be disallowed
final class Bop2
def f3(x: Bop2) = x match { case Seq('b', 'o', 'b') => true } // fail
// final, invariant type parameter, should be disallowed
def f4[T](x: Bop3[Char]) = x match { case Seq('b', 'o', 'b') => true } // fail
}
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