From 034489b50158756b57091a04830d94160975bddb Mon Sep 17 00:00:00 2001 From: Paul Phillips Date: Fri, 24 Jun 2011 05:42:08 +0000 Subject: 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. --- test/files/pos/bug4501.scala | 14 ++++++++++++++ 1 file changed, 14 insertions(+) create mode 100644 test/files/pos/bug4501.scala (limited to 'test/files/pos/bug4501.scala') diff --git a/test/files/pos/bug4501.scala b/test/files/pos/bug4501.scala new file mode 100644 index 0000000000..40628f1a4b --- /dev/null +++ b/test/files/pos/bug4501.scala @@ -0,0 +1,14 @@ +// After lub modification +import scala.collection.mutable.ListBuffer + +class A { + def foo[T](a:T, b:T):T = a + def f1 = foo(ListBuffer(), List()) + def f2 = foo(ListBuffer(), ListBuffer()) + def f3 = foo(List(), List()) + + // scalap + // def f1 : scala.collection.Seq[scala.Nothing] = { /* compiled code */ } + // def f2 : scala.collection.mutable.ListBuffer[scala.Nothing] = { /* compiled code */ } + // def f3 : scala.collection.immutable.List[scala.Nothing] = { /* compiled code */ } +} \ No newline at end of file -- cgit v1.2.3