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author | Guillaume Martres <smarter@ubuntu.com> | 2015-11-25 00:07:13 +0100 |
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committer | Guillaume Martres <smarter@ubuntu.com> | 2015-11-25 02:11:17 +0100 |
commit | 81b7ed9abb9627d541b795990980f4431b459380 (patch) | |
tree | 86b9976cdcaee86082e9d8c35ed24fe59d9c2cc3 | |
parent | 4463f5e705480c7da188695abdb0ccacf452103c (diff) | |
download | dotty-81b7ed9abb9627d541b795990980f4431b459380.tar.gz dotty-81b7ed9abb9627d541b795990980f4431b459380.tar.bz2 dotty-81b7ed9abb9627d541b795990980f4431b459380.zip |
isSubtype: try to dealias TypeRefs before recursively checking the prefixes
As demonstrated by tests/pos/hk-deep-subtype.scala, we can avoid some
deep subtype recursions that result in stack overflows by doing this.
Fix #943.
-rw-r--r-- | src/dotty/tools/dotc/core/TypeComparer.scala | 9 | ||||
-rw-r--r-- | test/dotc/scala-collections.whitelist | 9 | ||||
-rw-r--r-- | tests/pos/hk-deep-subtype.scala | 15 |
3 files changed, 23 insertions, 10 deletions
diff --git a/src/dotty/tools/dotc/core/TypeComparer.scala b/src/dotty/tools/dotc/core/TypeComparer.scala index 6e2346710..0d46a4b90 100644 --- a/src/dotty/tools/dotc/core/TypeComparer.scala +++ b/src/dotty/tools/dotc/core/TypeComparer.scala @@ -144,8 +144,7 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling { case info2: TypeAlias => isSubType(tp1, info2.alias) case _ => info1 match { case info1: TypeAlias => isSubType(info1.alias, tp2) - case NoType => secondTry(tp1, tp2) - case _ => thirdTryNamed(tp1, tp2) + case _ => false } } def compareNamed = { @@ -153,6 +152,7 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling { tp1 match { case tp1: NamedType => val sym1 = tp1.symbol + compareAlias(tp1.info) || (if ((sym1 ne NoSymbol) && (sym1 eq tp2.symbol)) ctx.erasedTypes || sym1.isStaticOwner || isSubType(tp1.prefix, tp2.prefix) else @@ -164,10 +164,11 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling { ) || compareHK(tp1, tp2, inOrder = true) || compareHK(tp2, tp1, inOrder = false) || - compareAlias(tp1.info) + thirdTryNamed(tp1, tp2) case _ => compareHK(tp2, tp1, inOrder = false) || - compareAlias(NoType) + compareAlias(NoType) || + secondTry(tp1, tp2) } } compareNamed diff --git a/test/dotc/scala-collections.whitelist b/test/dotc/scala-collections.whitelist index a758f9a8c..25cd73629 100644 --- a/test/dotc/scala-collections.whitelist +++ b/test/dotc/scala-collections.whitelist @@ -263,16 +263,13 @@ ./scala-scala/src/library/scala/collection/generic/GenericSeqCompanion.scala ./scala-scala/src/library/scala/collection/generic/GenericSetTemplate.scala -# deep subtype -#./scala-scala/src/library/scala/collection/generic/GenericTraversableTemplate.scala +./scala-scala/src/library/scala/collection/generic/GenericTraversableTemplate.scala ./scala-scala/src/library/scala/collection/generic/HasNewBuilder.scala ./scala-scala/src/library/scala/collection/generic/HasNewCombiner.scala -# https://github.com/lampepfl/dotty/issues/943 -# [error] Test dotc.tests.compileStdLib failed: java.lang.Error: deep subtype, took 6.462 sec -#./scala-scala/src/library/scala/collection/generic/ImmutableMapFactory.scala -#./scala-scala/src/library/scala/collection/generic/ImmutableSetFactory.scala +./scala-scala/src/library/scala/collection/generic/ImmutableMapFactory.scala +./scala-scala/src/library/scala/collection/generic/ImmutableSetFactory.scala ./scala-scala/src/library/scala/collection/generic/ImmutableSortedMapFactory.scala ./scala-scala/src/library/scala/collection/generic/ImmutableSortedSetFactory.scala diff --git a/tests/pos/hk-deep-subtype.scala b/tests/pos/hk-deep-subtype.scala new file mode 100644 index 000000000..202329a79 --- /dev/null +++ b/tests/pos/hk-deep-subtype.scala @@ -0,0 +1,15 @@ +// Minimized from scala.collection.generic.GenTraversableFactory plus dependencies +import scala.annotation.unchecked.uncheckedVariance + +trait GT[A] extends GTT[A, GT] + +trait HNB[B] +trait GTT[+C, DD[X] <: GT[X]] extends HNB[DD[C] @uncheckedVariance] // Can be any annotation and still crash + +class GTF[EE[X] <: GT[X] with GTT[X, EE]] +{ + def foo[F]: EE[F] = ??? + def bar[G](f: G): EE[G] = ??? + + def tabulate: EE[EE[Int]] = bar(foo) +} |