diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/compiler/scala/reflect/internal/Types.scala | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/src/compiler/scala/reflect/internal/Types.scala b/src/compiler/scala/reflect/internal/Types.scala index e8b9dc0865..b5777c099f 100644 --- a/src/compiler/scala/reflect/internal/Types.scala +++ b/src/compiler/scala/reflect/internal/Types.scala @@ -90,6 +90,8 @@ trait Types /*extends reflect.generic.Types*/ { self: SymbolTable => private final def decr(depth: Int) = if (depth == AnyDepth) AnyDepth else depth - 1 private final val printLubs = false + /** In case anyone wants to turn off lub verification without reverting anything. */ + private final val verifyLubs = true /** The current skolemization level, needed for the algorithms * in isSameType, isSubType that do constraint solving under a prefix. @@ -5310,9 +5312,25 @@ A type's typeSymbol should never be inspected directly. } } if (lubRefined.decls.isEmpty) lubBase + else if (!verifyLubs) lubRefined else { -// println("refined lub of "+ts+"/"+narrowts+" is "+lubRefined+", baseclasses = "+(ts map (_.baseTypeSeq) map (_.toList))) - lubRefined + // Verify that every given type conforms to the calculated lub. + // In theory this should not be necessary, but higher-order type + // parameters are not handled correctly. + val ok = ts forall { t => + (t <:< lubRefined) || { + if (settings.debug.value) { + Console.println( + "Malformed lub: " + lubRefined + "\n" + + "Argument " + t + " does not conform. Falling back to " + lubBase + ) + } + false + } + } + // If not, fall back on the more conservative calculation. + if (ok) lubRefined + else lubBase } } existentialAbstraction(tparams, lubType) |