From 7f2eaea3e7f08c6fcb53b6c7d7f35bbb4a82ebf5 Mon Sep 17 00:00:00 2001 From: Adriaan Moors Date: Tue, 6 Oct 2009 10:44:57 +0000 Subject: fixed #2421: checkBounds in typedImplicit0 to f... fixed #2421: checkBounds in typedImplicit0 to filter out implicit searchresults that result in nonsenical type instantiations --- test/files/pos/t2421_delitedsl.scala | 37 ++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 test/files/pos/t2421_delitedsl.scala (limited to 'test/files/pos/t2421_delitedsl.scala') diff --git a/test/files/pos/t2421_delitedsl.scala b/test/files/pos/t2421_delitedsl.scala new file mode 100644 index 0000000000..a05887023a --- /dev/null +++ b/test/files/pos/t2421_delitedsl.scala @@ -0,0 +1,37 @@ +trait DeliteDSL { + abstract class <~<[-From, +To] extends (From => To) + implicit def trivial[A]: A <~< A = new (A <~< A) {def apply(x: A) = x} + + trait Forcible[T] + object Forcible { + def factory[T](f: T => Forcible[T]) = new (T <~< Forcible[T]){def apply(x: T) = f(x)} + } + + case class DeliteInt(x: Int) extends Forcible[Int] + implicit val forcibleInt = Forcible.factory(DeliteInt(_: Int)) + + import scala.collection.Traversable + class DeliteCollection[T](val xs: Traversable[T]) { + // must use existential in bound of P, instead of T itself, because we cannot both have: + // Test.x below: DeliteCollection[T=Int] -> P=DeliteInt <: Forcible[T=Int], as T=Int <~< P=DeliteInt + // Test.xAlready below: DeliteCollection[T=DeliteInt] -> P=DeliteInt <: Forcible[T=DeliteInt], as T=DeliteInt <~< P=DeliteInt + // this would required DeliteInt <: Forcible[Int] with Forcible[DeliteInt] + + def headProxy[P <: Forcible[_]](implicit w: T <~< P): P = xs.head + } + // If T is already a proxy (it is forcible), the compiler should use + // forcibleIdentity to deduce that P=T. If T is Int, the compiler + // should use intToForcible to deduce that P=DeliteInt. + // + // Without this feature, the user must write 'xs.proxyOfFirst[DeliteInt]', + // with the feature they can write 'xs.proxyOfFirst', which is shorter and + // avoids exposing internal DELITE types to the world. + + object Test { + val x = new DeliteCollection(List(1,2,3)).headProxy + // inferred: val x: Forcible[Int] = new DeliteCollection[Int](List.apply[Int](1, 2, 3)).headProxy[Forcible[Int]](forcibleInt); + + val xAlready = new DeliteCollection(List(DeliteInt(1),DeliteInt(2),DeliteInt(3))).headProxy + // inferred: val xAlready: DeliteInt = new DeliteCollection[DeliteInt](List.apply[DeliteInt](DeliteInt(1), DeliteInt(2), DeliteInt(3))).headProxy[DeliteInt](trivial[DeliteInt]); + } +} \ No newline at end of file -- cgit v1.2.3