Merge remote-tracking branches 'adriaanm/ticket/5189' and 'jsuereth/better-starr-flow' into develop

Author: paulp

build.xml

@@ -2010,9 +2010,28 @@ STABLE REFERENCE (STARR)
         <include name="forkjoin.jar"/>
       </fileset>
     </copy>
+    <!-- remove SHA1 files for no starr, so we don't loose artifacts. -->
+    <delete>
+      <fileset dir="${lib.dir}">
+        <include name="fjbg.jar.desired.sha1"/>
+        <include name="msil.jar.desired.sha1"/>
+        <include name="forkjoin.jar.desired.sha1"/>
+      </fileset>
+    </delete>
+  </target>
+
+  <target name="starr.removesha1" depends="starr.libs">
+    <!-- remove SHA1 files for no starr, so we don't loose artifacts. -->
+    <delete>
+      <fileset dir="${lib.dir}">
+        <include name="scala-compiler.jar.desired.sha1"/>
+        <include name="scala-library.jar.desired.sha1"/>
+        <include name="scala-library-src.jar.desired.sha1"/>
+      </fileset>
+    </delete>
   </target>
 
-  <target name="starr.done" depends="starr.libs"/>
+  <target name="starr.done" depends="starr.libs, starr.removesha1"/>
 
 <!-- ===========================================================================
 FORWARDED TARGETS FOR PACKAGING

src/compiler/scala/reflect/internal/Symbols.scala

@@ -269,9 +269,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     /** Create a new existential type skolem with this symbol its owner,
      *  based on the given symbol and origin.
      */
-    def newExistentialSkolem(basis: Symbol, origin: AnyRef): TypeSkolem = {
-      val skolem = newTypeSkolemSymbol(basis.name.toTypeName, origin, basis.pos, (basis.flags | EXISTENTIAL) & ~PARAM)
-      skolem setInfo (basis.info cloneInfo skolem)
+    def newExistentialSkolem(basis: Symbol, origin: AnyRef, name: TypeName = null, info: Type = null): TypeSkolem = {
+      val skolem = newTypeSkolemSymbol(if (name eq null) basis.name.toTypeName else name, origin, basis.pos, (basis.flags | EXISTENTIAL) & ~PARAM)
+      skolem setInfo (if (info eq null) basis.info cloneInfo skolem else info)
     }
 
     final def newExistential(name: TypeName, pos: Position = NoPosition, newFlags: Long = 0L): Symbol =

src/compiler/scala/tools/nsc/io/Pickler.scala

@@ -165,7 +165,7 @@ object Pickler {
   def pkl[T: Pickler] = implicitly[Pickler[T]]
 
   /** A class represenenting `~`-pairs */
-  case class ~[S, T](fst: S, snd: T)
+  case class ~[+S, +T](fst: S, snd: T)
 
   /** A wrapper class to be able to use `~` s an infix method */
   class TildeDecorator[S](x: S) {

src/compiler/scala/tools/nsc/typechecker/Infer.scala

@@ -1051,49 +1051,74 @@ trait Infer {
      *  @param pt          the expected result type of the instance
      */
     def inferConstructorInstance(tree: Tree, undetparams: List[Symbol], pt0: Type) {
-      val pt = widen(pt0)
-      //println("infer constr inst "+tree+"/"+undetparams+"/"+pt0)
-      var restpe = tree.tpe.finalResultType
-      var tvars = undetparams map freshVar
+      val pt       = widen(pt0)
+      val ptparams = freeTypeParamsOfTerms.collect(pt)
+      val ctorTp   = tree.tpe
+      val resTp    = ctorTp.finalResultType
 
-      /** Compute type arguments for undetermined params and substitute them in given tree.
+      debuglog("infer constr inst "+ tree +"/"+ undetparams +"/ pt= "+ pt +" pt0= "+ pt0 +" resTp: "+ resTp)
+
+      /** Compute type arguments for undetermined params
        */
-      def computeArgs =
-        try {
-          val targs = solvedTypes(tvars, undetparams, undetparams map varianceInType(restpe),
-                                  true, lubDepth(List(restpe, pt)))
-//          checkBounds(tree, NoPrefix, NoSymbol, undetparams, targs, "inferred ")
-//          no checkBounds here. If we enable it, test bug602 fails.
-          new TreeTypeSubstituter(undetparams, targs).traverse(tree)
-        } catch ifNoInstance{ msg =>
-          NoConstructorInstanceError(tree, restpe, pt, msg)
+      def inferFor(pt: Type): Option[List[Type]] = {
+        val tvars   = undetparams map freshVar
+        val resTpV  = resTp.instantiateTypeParams(undetparams, tvars)
+
+        if (resTpV <:< pt) {
+          try {
+            // debuglog("TVARS "+ (tvars map (_.constr)))
+            // look at the argument types of the primary constructor corresponding to the pattern
+            val variances  = undetparams map varianceInType(ctorTp.paramTypes.headOption getOrElse ctorTp)
+            val targs      = solvedTypes(tvars, undetparams, variances, true, lubDepth(List(resTp, pt)))
+            // checkBounds(tree, NoPrefix, NoSymbol, undetparams, targs, "inferred ")
+            // no checkBounds here. If we enable it, test bug602 fails.
+            // TODO: reinstate checkBounds, return params that fail to meet their bounds to undetparams
+            Some(targs)
+          } catch ifNoInstance { msg =>
+            debuglog("NO INST "+ (tvars, tvars map (_.constr)))
+            NoConstructorInstanceError(tree, resTp, pt, msg)
+            None
+          }
+        } else {
+          debuglog("not a subtype: "+ resTpV +" </:< "+ pt)
+          None
         }
-      def instError = {
-        if (settings.debug.value) Console.println("ici " + tree + " " + undetparams + " " + pt)
-        if (settings.explaintypes.value) explainTypes(restpe.instantiateTypeParams(undetparams, tvars), pt)
-        ConstrInstantiationError(tree, restpe, pt)
       }
-      if (restpe.instantiateTypeParams(undetparams, tvars) <:< pt) {
-        computeArgs
-      } else if (isFullyDefined(pt)) {
-        debuglog("infer constr " + tree + ":" + restpe + ", pt = " + pt)
-        var ptparams = freeTypeParamsOfTerms.collect(pt)
-        debuglog("free type params = " + ptparams)
-        val ptWithWildcards = pt.instantiateTypeParams(ptparams, ptparams map (ptparam => WildcardType))
-        tvars = undetparams map freshVar
-        if (restpe.instantiateTypeParams(undetparams, tvars) <:< ptWithWildcards) {
-          computeArgs
-          restpe = skipImplicit(tree.tpe.resultType)
-          debuglog("new tree = " + tree + ":" + restpe)
-          val ptvars = ptparams map freshVar
-          val pt1 = pt.instantiateTypeParams(ptparams, ptvars)
-          if (isPopulated(restpe, pt1)) {
-            ptvars foreach instantiateTypeVar
-          } else { if (settings.debug.value) Console.println("no instance: "); instError }
-        } else { if (settings.debug.value) Console.println("not a subtype " + restpe.instantiateTypeParams(undetparams, tvars) + " of " + ptWithWildcards); instError }
-      } else { if (settings.debug.value) Console.println("not fully defined: " + pt); instError }
+
+      def inferForApproxPt =
+        if (isFullyDefined(pt)) {
+          inferFor(pt.instantiateTypeParams(ptparams, ptparams map (x => WildcardType))) flatMap { targs =>
+            val ctorTpInst = tree.tpe.instantiateTypeParams(undetparams, targs)
+            val resTpInst  = skipImplicit(ctorTpInst.finalResultType)
+            val ptvars     =
+              ptparams map {
+                // since instantiateTypeVar wants to modify the skolem that corresponds to the method's type parameter,
+                // and it uses the TypeVar's origin to locate it, deskolemize the existential skolem to the method tparam skolem
+                // (the existential skolem was created by adaptConstrPattern to introduce the type slack necessary to soundly deal with variant type parameters)
+                case skolem if skolem.isExistentialSkolem => freshVar(skolem.deSkolemize.asInstanceOf[TypeSymbol])
+                case p => freshVar(p)
+              }
+
+            val ptV        = pt.instantiateTypeParams(ptparams, ptvars)
+
+            if (isPopulated(resTpInst, ptV)) {
+              ptvars foreach instantiateTypeVar
+              debuglog("isPopulated "+ resTpInst +", "+ ptV +" vars= "+ ptvars)
+              Some(targs)
+            } else None
+          }
+        } else None
+
+      (inferFor(pt) orElse inferForApproxPt) map { targs =>
+        new TreeTypeSubstituter(undetparams, targs).traverse(tree)
+      } getOrElse {
+        debugwarn("failed inferConstructorInstance for "+ tree  +" : "+ tree.tpe +" under "+ undetparams +" pt = "+ pt +(if(isFullyDefined(pt)) " (fully defined)" else " (not fully defined)"))
+        // if (settings.explaintypes.value) explainTypes(resTp.instantiateTypeParams(undetparams, tvars), pt)
+        ConstrInstantiationError(tree, resTp, pt)
+      }
     }
 
+
     def instBounds(tvar: TypeVar): (Type, Type) = {
       val tparam = tvar.origin.typeSymbol
       val instType = toOrigin(tvar.constr.inst)

src/compiler/scala/tools/nsc/typechecker/Typers.scala

@@ -864,6 +864,33 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
         }
       }
 
+      /**
+       * To deal with the type slack between actual (run-time) types and statically known types, for each abstract type T,
+       * reflect its variance as a skolem that is upper-bounded by T (covariant position), or lower-bounded by T (contravariant).
+       *
+       * Consider the following example:
+       *
+       *  class AbsWrapperCov[+A]
+       *  case class Wrapper[B](x: Wrapped[B]) extends AbsWrapperCov[B]
+       *
+       *  def unwrap[T](x: AbsWrapperCov[T]): Wrapped[T] = x match {
+       *    case Wrapper(wrapped) => // Wrapper's type parameter must not be assumed to be equal to T, it's *upper-bounded* by it
+       *      wrapped // : Wrapped[_ <: T]
+       *  }
+       *
+       * this method should type check if and only if Wrapped is covariant in its type parameter
+       *
+       * when inferring Wrapper's type parameter B from x's type AbsWrapperCov[T],
+       * we must take into account that x's actual type is AbsWrapperCov[Tactual] forSome {type Tactual <: T}
+       * as AbsWrapperCov is covariant in A -- in other words, we must not assume we know T exactly, all we know is its upper bound
+       *
+       * since method application is the only way to generate this slack between run-time and compile-time types (TODO: right!?),
+       * we can simply replace skolems that represent method type parameters as seen from the method's body
+       * by other skolems that are (upper/lower)-bounded by that type-parameter skolem
+       * (depending on the variance position of the skolem in the statically assumed type of the scrutinee, pt)
+       *
+       * see test/files/../t5189*.scala
+       */
       def adaptConstrPattern(): Tree = { // (5)
         val extractor = tree.symbol.filter(sym => reallyExists(unapplyMember(sym.tpe)))
         if (extractor != NoSymbol) {
@@ -877,7 +904,32 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
             val tree1 = TypeTree(clazz.primaryConstructor.tpe.asSeenFrom(prefix, clazz.owner))
               .setOriginal(tree)
 
-            inferConstructorInstance(tree1, clazz.typeParams, pt)
+            val skolems = new mutable.ListBuffer[TypeSymbol]
+            object variantToSkolem extends VariantTypeMap {
+              def apply(tp: Type) = mapOver(tp) match {
+                case TypeRef(NoPrefix, tpSym, Nil) if variance != 0 && tpSym.isTypeParameterOrSkolem && tpSym.owner.isTerm =>
+                  val bounds = if (variance == 1) TypeBounds.upper(tpSym.tpe) else TypeBounds.lower(tpSym.tpe)
+                  val skolem = context.owner.newExistentialSkolem(tpSym, tpSym, unit.freshTypeName("?"+tpSym.name), bounds)
+                  // println("mapping "+ tpSym +" to "+ skolem + " : "+ bounds +" -- pt= "+ pt)
+                  skolems += skolem
+                  skolem.tpe
+                case tp1 => tp1
+              }
+            }
+
+            // have to open up the existential and put the skolems in scope
+            // can't simply package up pt in an ExistentialType, because that takes us back to square one (List[_ <: T] == List[T] due to covariance)
+            val ptSafe   = variantToSkolem(pt) // TODO: pt.skolemizeExistential(context.owner, tree) ?
+            val freeVars = skolems.toList
+
+            // use "tree" for the context, not context.tree: don't make another CaseDef context,
+            // as instantiateTypeVar's bounds would end up there
+            val ctorContext = context.makeNewScope(tree, context.owner)
+            freeVars foreach ctorContext.scope.enter
+            newTyper(ctorContext).infer.inferConstructorInstance(tree1, clazz.typeParams, ptSafe)
+
+            // tree1's type-slack skolems will be deskolemized (to the method type parameter skolems)
+            // once the containing CaseDef has been type checked (see typedCase)
             tree1
           } else {
             tree
@@ -1998,15 +2050,35 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
       val guard1: Tree = if (cdef.guard == EmptyTree) EmptyTree
                          else typed(cdef.guard, BooleanClass.tpe)
       var body1: Tree = typed(cdef.body, pt)
-      if (!context.savedTypeBounds.isEmpty) {
-        body1.tpe = context.restoreTypeBounds(body1.tpe)
-        if (isFullyDefined(pt) && !(body1.tpe <:< pt)) {
-          // @M no need for pt.normalize here, is done in erasure
+
+      val contextWithTypeBounds = context.nextEnclosing(_.tree.isInstanceOf[CaseDef])
+      if (contextWithTypeBounds.savedTypeBounds nonEmpty) {
+        body1.tpe = contextWithTypeBounds restoreTypeBounds body1.tpe
+
+        // insert a cast if something typechecked under the GADT constraints,
+        // but not in real life (i.e., now that's we've reset the method's type skolems'
+        //   infos back to their pre-GADT-constraint state)
+        if (isFullyDefined(pt) && !(body1.tpe <:< pt))
           body1 = typedPos(body1.pos)(gen.mkCast(body1, pt))
-        }
+
       }
+
 //    body1 = checkNoEscaping.locals(context.scope, pt, body1)
-      treeCopy.CaseDef(cdef, pat1, guard1, body1) setType body1.tpe
+      val treeWithSkolems = treeCopy.CaseDef(cdef, pat1, guard1, body1) setType body1.tpe
+
+      // undo adaptConstrPattern's evil deeds, as they confuse the old pattern matcher
+      // TODO: Paul, can we do the deskolemization lazily in the old pattern matcher
+      object deskolemizeOnce extends TypeMap {
+        def apply(tp: Type): Type = mapOver(tp) match {
+          case TypeRef(pre, sym, args) if sym.isExistentialSkolem && sym.deSkolemize.isSkolem && sym.deSkolemize.owner.isTerm =>
+            typeRef(NoPrefix, sym.deSkolemize, args)
+          case tp1 => tp1
+        }
+      }
+
+      new TypeMapTreeSubstituter(deskolemizeOnce).traverse(treeWithSkolems)
+
+      treeWithSkolems // now without skolems, actually
     }
 
     def typedCases(cases: List[CaseDef], pattp: Type, pt: Type): List[CaseDef] =

src/library/scala/collection/JavaConversions.scala

@@ -69,7 +69,7 @@ object JavaConversions {
    * @return A Java Iterator view of the argument.
    */
   implicit def asJavaIterator[A](it: Iterator[A]): ju.Iterator[A] = it match {
-    case JIteratorWrapper(wrapped) => wrapped
+    case JIteratorWrapper(wrapped) => wrapped.asInstanceOf[ju.Iterator[A]]
     case _ => IteratorWrapper(it)
   }
 
@@ -87,7 +87,7 @@ object JavaConversions {
    * @return A Java Enumeration view of the argument.
    */
   implicit def asJavaEnumeration[A](it: Iterator[A]): ju.Enumeration[A] = it match {
-    case JEnumerationWrapper(wrapped) => wrapped
+    case JEnumerationWrapper(wrapped) => wrapped.asInstanceOf[ju.Enumeration[A]]
     case _ => IteratorWrapper(it)
   }
 
@@ -105,7 +105,7 @@ object JavaConversions {
    * @return A Java Iterable view of the argument.
    */
   implicit def asJavaIterable[A](i: Iterable[A]): jl.Iterable[A] = i match {
-    case JIterableWrapper(wrapped) => wrapped
+    case JIterableWrapper(wrapped) => wrapped.asInstanceOf[jl.Iterable[A]]
     case _ => IterableWrapper(i)
   }
 
@@ -121,7 +121,7 @@ object JavaConversions {
    * @return A Java Collection view of the argument.
    */
   implicit def asJavaCollection[A](it: Iterable[A]): ju.Collection[A] = it match {
-    case JCollectionWrapper(wrapped) => wrapped
+    case JCollectionWrapper(wrapped) => wrapped.asInstanceOf[ju.Collection[A]]
     case _ => new IterableWrapper(it)
   }
 
@@ -179,7 +179,7 @@ object JavaConversions {
    * @return A Java List view of the argument.
    */
   implicit def seqAsJavaList[A](seq: Seq[A]): ju.List[A] = seq match {
-    case JListWrapper(wrapped) => wrapped
+    case JListWrapper(wrapped) => wrapped.asInstanceOf[ju.List[A]]
     case _ => new SeqWrapper(seq)
   }
 
@@ -286,7 +286,7 @@ object JavaConversions {
    */
   implicit def mapAsJavaMap[A, B](m: Map[A, B]): ju.Map[A, B] = m match {
     //case JConcurrentMapWrapper(wrapped) => wrapped
-    case JMapWrapper(wrapped) => wrapped
+    case JMapWrapper(wrapped) => wrapped.asInstanceOf[ju.Map[A, B]]
     case _ => new MapWrapper(m)
   }
 

src/library/scala/collection/immutable/IntMap.scala

@@ -353,19 +353,19 @@ extends AbstractMap[Int, T]
   def unionWith[S >: T](that : IntMap[S], f : (Int, S, S) => S) : IntMap[S] = (this, that) match{
     case (IntMap.Bin(p1, m1, l1, r1), that@(IntMap.Bin(p2, m2, l2, r2))) =>
       if (shorter(m1, m2)) {
-        if (!hasMatch(p2, p1, m1)) join(p1, this, p2, that);
+        if (!hasMatch(p2, p1, m1)) join[S](p1, this, p2, that); // TODO: remove [S] when SI-5548 is fixed
         else if (zero(p2, m1)) IntMap.Bin(p1, m1, l1.unionWith(that, f), r1);
         else IntMap.Bin(p1, m1, l1, r1.unionWith(that, f));
       } else if (shorter(m2, m1)){
-        if (!hasMatch(p1, p2, m2)) join(p1, this, p2, that);
+        if (!hasMatch(p1, p2, m2)) join[S](p1, this, p2, that); // TODO: remove [S] when SI-5548 is fixed
         else if (zero(p1, m2)) IntMap.Bin(p2, m2, this.unionWith(l2, f), r2);
         else IntMap.Bin(p2, m2, l2, this.unionWith(r2, f));
       }
       else {
         if (p1 == p2) IntMap.Bin(p1, m1, l1.unionWith(l2,f), r1.unionWith(r2, f));
-        else join(p1, this, p2, that);
+        else join[S](p1, this, p2, that); // TODO: remove [S] when SI-5548 is fixed
       }
-    case (IntMap.Tip(key, value), x) => x.updateWith(key, value, (x, y) => f(key, y, x));
+    case (IntMap.Tip(key, value), x) => x.updateWith[S](key, value, (x, y) => f(key, y, x));
     case (x, IntMap.Tip(key, value)) => x.updateWith[S](key, value, (x, y) => f(key, x, y));
     case (IntMap.Nil, x) => x;
     case (x, IntMap.Nil) => x;

src/library/scala/collection/immutable/LongMap.scala

@@ -349,19 +349,19 @@ extends AbstractMap[Long, T]
   def unionWith[S >: T](that : LongMap[S], f : (Long, S, S) => S) : LongMap[S] = (this, that) match{
     case (LongMap.Bin(p1, m1, l1, r1), that@(LongMap.Bin(p2, m2, l2, r2))) =>
       if (shorter(m1, m2)) {
-        if (!hasMatch(p2, p1, m1)) join(p1, this, p2, that);
+        if (!hasMatch(p2, p1, m1)) join[S](p1, this, p2, that); // TODO: remove [S] when SI-5548 is fixed
         else if (zero(p2, m1)) LongMap.Bin(p1, m1, l1.unionWith(that, f), r1);
         else LongMap.Bin(p1, m1, l1, r1.unionWith(that, f));
       } else if (shorter(m2, m1)){
-        if (!hasMatch(p1, p2, m2)) join(p1, this, p2, that);
+        if (!hasMatch(p1, p2, m2)) join[S](p1, this, p2, that); // TODO: remove [S] when SI-5548 is fixed
         else if (zero(p1, m2)) LongMap.Bin(p2, m2, this.unionWith(l2, f), r2);
         else LongMap.Bin(p2, m2, l2, this.unionWith(r2, f));
       }
       else {
         if (p1 == p2) LongMap.Bin(p1, m1, l1.unionWith(l2,f), r1.unionWith(r2, f));
-        else join(p1, this, p2, that);
+        else join[S](p1, this, p2, that); // TODO: remove [S] when SI-5548 is fixed
       }
-    case (LongMap.Tip(key, value), x) => x.updateWith(key, value, (x, y) => f(key, y, x));
+    case (LongMap.Tip(key, value), x) => x.updateWith[S](key, value, (x, y) => f(key, y, x)); // TODO: remove [S] when SI-5548 is fixed
     case (x, LongMap.Tip(key, value)) => x.updateWith[S](key, value, (x, y) => f(key, x, y));
     case (LongMap.Nil, x) => x;
     case (x, LongMap.Nil) => x;