diff options
author | Paul Phillips <paulp@improving.org> | 2011-06-24 05:42:08 +0000 |
---|---|---|
committer | Paul Phillips <paulp@improving.org> | 2011-06-24 05:42:08 +0000 |
commit | 034489b50158756b57091a04830d94160975bddb (patch) | |
tree | 4b695b2c00f7d464b893842ad8e729404b62c69b /test/pending | |
parent | 5dc127e69cae1d88aa6910ea6378ad5dc1aaeaab (diff) | |
download | scala-034489b50158756b57091a04830d94160975bddb.tar.gz scala-034489b50158756b57091a04830d94160975bddb.tar.bz2 scala-034489b50158756b57091a04830d94160975bddb.zip |
Added sanity check to lub calculation to preven...
Added sanity check to lub calculation to prevent invalid lubs from
emerging. The underlying cause of said lubs is that higher-order
type parameters are not handled correctly: this is why the issue
is seen so frequently in the collections. See pending test
pending/pos/those-kinds-are-high.scala for a demonstration. Until that's
fixed, we can at least raise the bar a bit.
Closes #2094, #2322, #4501. Also, some test cases in neg have been
promoted into working programs: #2179, #3774. (They're not in neg for
the "shouldn't work" reason, but out of despair.)
In some cases, such as the original reported ticket in #3528, this
only pushes the problem downfield: it still fails due to inferred type
parameters not conforming to bounds. I believe a similar issue with
higher-order type parameters underlies that.
Look at how far this takes us though. All kinds of stuff which did not
work, now works. None of these even compiled until now:
scala> :type List(mutable.Map(1 -> 1), immutable.Map(1 -> 1))
List[scala.collection.Map[Int,Int]]
scala> :type Set(List(1), mutable.Map(1 -> 1))
scala.collection.Set[Iterable[Any] with PartialFunction[Int,Int]]
scala> :type Stream(List(1), Set(1), 1 to 5)
Stream[Iterable[Int] with Int => AnyVal{def getClass(): Class[_ >: Int with Boolean <: AnyVal]}]
scala> :type Map(1 -> (1 to 10), 2 -> (1 to 10).toList)
scala.collection.immutable.Map[Int,scala.collection.immutable.Seq[Int]
]
PERFORMANCE: compiling quick.lib and quick.comp, this patch results in
an extra 27 subtype tests. Total. Time difference too small to measure.
However to be on the safe side I made it really easy to disable.
private final val verifyLubs = true // set to false
Review by moors, odersky.
Diffstat (limited to 'test/pending')
-rw-r--r-- | test/pending/pos/those-kinds-are-high.scala | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/test/pending/pos/those-kinds-are-high.scala b/test/pending/pos/those-kinds-are-high.scala new file mode 100644 index 0000000000..d3ee2bf308 --- /dev/null +++ b/test/pending/pos/those-kinds-are-high.scala @@ -0,0 +1,37 @@ +class A { + trait Container[+T] + trait Template[+CC[X] <: Container[X]] + + class C1[T] extends Template[C1] with Container[T] + class C2[T] extends Template[C2] with Container[T] + + /** Target expression: + * List(new C1[String], new C2[String]) + */ + + // Here's what would ideally be inferred. + // + // scala> :type List[Template[Container] with Container[String]](new C1[String], new C2[String]) + // List[Template[Container] with Container[java.lang.String]] + // + // Here's what it does infer. + // + // scala> :type List(new C1[String], new C2[String]) + // <console>:8: error: type mismatch; + // found : C1[String] + // required: Container[String] with Template[Container[Any] with Template[Container[Any] with Template[Any] with ScalaObject] with ScalaObject] with ScalaObject + // List(new C1[String], new C2[String]) + // ^ + // + // Simplified, the inferred type is: + // + // List[Container[String] with Template[Container[Any] with Template[Container[Any] with Template[Any]]] + // + + /** Working version explicitly typed. + */ + def fExplicit = List[Template[Container] with Container[String]](new C1[String], new C2[String]) + + // nope + // def fFail = List(new C1[String], new C2[String]) +} |