diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala index 2ee3570905..c466206192 100644 --- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala +++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala @@ -2153,6 +2153,21 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL // the equals inherited from AnyRef does just this } + // find most precise super-type of tp that is a class + // we skip non-class types (singleton types, abstract types) so that we can + // correctly compute how types relate in terms of the values they rule out + // e.g., when we know some value must be of type T, can it still be of type S? (this is the positive formulation of what `excludes` on Const computes) + // since we're talking values, there must have been a class involved in creating it, so rephrase our types in terms of classes + // (At least conceptually: `true` is an instance of class `Boolean`) + private def widenToClass(tp: Type) = { + // getOrElse to err on the safe side -- all BTS should end in Any, right? + val wideTp = tp.widen + val clsTp = + if (wideTp.typeSymbol.isClass) wideTp + else wideTp.baseTypeSeq.toList.find(_.typeSymbol.isClass).getOrElse(AnyClass.tpe) + // patmatDebug("Widening to class: "+ (tp, clsTp, tp.widen, tp.widen.baseTypeSeq, tp.widen.baseTypeSeq.toList.find(_.typeSymbol.isClass))) + clsTp + } object TypeConst { def apply(tp: Type) = { @@ -2168,7 +2183,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL assert(!(tp =:= NullTp)) private[this] val id: Int = Const.nextTypeId - val wideTp = tp.widen + val wideTp = widenToClass(tp) override def toString = tp.toString //+"#"+ id } @@ -2187,10 +2202,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL val tp = p.tpe.normalize if (tp =:= NullTp) NullConst else { - val wideTp = { - if (p.hasSymbol && p.symbol.isStable) tp.asSeenFrom(tp.prefix, p.symbol.owner).widen - else tp.widen - } + val wideTp = widenToClass(tp) val narrowTp = if (tp.isInstanceOf[SingletonType]) tp |