diff options
4 files changed, 51 insertions, 12 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala index 68522c727f..4e8f416b16 100644 --- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala +++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala @@ -1429,6 +1429,12 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL // (Select(codegen._asInstanceOf(testedBinder, expectedTp), outer)) OBJ_EQ expectedOuter // } + // TODO: improve, e.g., for constants + def sameValue(a: Tree, b: Tree): Boolean = (a eq b) || ((a, b) match { + case (_ : Ident, _ : Ident) => a.symbol eq b.symbol + case _ => false + }) + // returns (tree, tests), where `tree` will be used to refer to `root` in `tests` abstract class TreeMakersToConds(val root: Symbol) { @@ -1476,13 +1482,6 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL // patmatDebug("accumSubst: "+ accumSubst) } - - // TODO: improve, e.g., for constants - def sameValue(a: Tree, b: Tree): Boolean = (a eq b) || ((a, b) match { - case (_ : Ident, _ : Ident) => a.symbol eq b.symbol - case _ => false - }) - // hashconsing trees (modulo value-equality) def unique(t: Tree, tpOverride: Type = NoType): Tree = trees find (a => a.correspondsStructure(t)(sameValue)) match { @@ -2075,7 +2074,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL // a literal constant becomes ConstantType(Constant(v)) when the type allows it (roughly, anyval + string + null) // equality between variables: SingleType(x) (note that pattern variables cannot relate to each other -- it's always patternVar == nonPatternVar) object Const { - def resetUniques() = {_nextTypeId = 0; _nextValueId = 0; uniques.clear()} // patmatDebug("RESET") + def resetUniques() = {_nextTypeId = 0; _nextValueId = 0; uniques.clear() ; trees.clear() } // patmatDebug("RESET") private var _nextTypeId = 0 def nextTypeId = {_nextTypeId += 1; _nextTypeId} @@ -2093,6 +2092,27 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL uniques(tp) = fresh fresh }) + + private val trees = collection.mutable.HashSet.empty[Tree] + + // hashconsing trees (modulo value-equality) + private[SymbolicMatchAnalysis] def uniqueTpForTree(t: Tree): Type = + // a new type for every unstable symbol -- only stable value are uniqued + // technically, an unreachable value may change between cases + // thus, the failure of a case that matches on a mutable value does not exclude the next case succeeding + // (and thuuuuus, the latter case must be considered reachable) + if (!t.symbol.isStable) t.tpe.narrow + else trees find (a => a.correspondsStructure(t)(sameValue)) match { + case Some(orig) => + // patmatDebug("unique: "+ (orig, orig.tpe)) + orig.tpe + case _ => + // duplicate, don't mutate old tree (TODO: use a map tree -> type instead?) + val treeWithNarrowedType = t.duplicate setType t.tpe.narrow + // patmatDebug("uniqued: "+ (t, t.tpe, treeWithNarrowedType.tpe)) + trees += treeWithNarrowedType + treeWithNarrowedType.tpe + } } sealed abstract class Const extends AbsConst { @@ -2181,11 +2201,13 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL case Literal(c) => if (c.tpe.typeSymbol == UnitClass) c.tpe else ConstantType(c) - case p if p.symbol.isStable => + case Ident(_) if p.symbol.isStable => + // for Idents, can encode uniqueness of symbol as uniqueness of the corresponding singleton type + // for Selects, which are handled by the next case, the prefix of the select varies independently of the symbol (see pos/virtpatmat_unreach_select.scala) singleType(tp.prefix, p.symbol) - case x => - // TODO: better type - x.tpe.narrow + case _ => + // patmatDebug("unique type for "+(p, Const.uniqueTpForTree(p))) + Const.uniqueTpForTree(p) } val toString = diff --git a/test/files/neg/virtpatmat_unreach_select.check b/test/files/neg/virtpatmat_unreach_select.check new file mode 100644 index 0000000000..3771971020 --- /dev/null +++ b/test/files/neg/virtpatmat_unreach_select.check @@ -0,0 +1,4 @@ +virtpatmat_unreach_select.scala:10: error: unreachable code + case WARNING.id => // unreachable + ^ +one error found diff --git a/test/files/neg/virtpatmat_unreach_select.flags b/test/files/neg/virtpatmat_unreach_select.flags new file mode 100644 index 0000000000..85d8eb2ba2 --- /dev/null +++ b/test/files/neg/virtpatmat_unreach_select.flags @@ -0,0 +1 @@ +-Xfatal-warnings diff --git a/test/files/neg/virtpatmat_unreach_select.scala b/test/files/neg/virtpatmat_unreach_select.scala new file mode 100644 index 0000000000..c46ff15453 --- /dev/null +++ b/test/files/neg/virtpatmat_unreach_select.scala @@ -0,0 +1,12 @@ +class Test { + object severity extends Enumeration + class Severity(val id: Int) extends severity.Value + val INFO = new Severity(0) + val WARNING = new Severity(1) + + (0: Int) match { + case WARNING.id => + case INFO.id => // reachable + case WARNING.id => // unreachable + } +} |