Fix strawmans

src/dotty/tools/dotc/ast/Desugar.scala

@@ -256,7 +256,21 @@ object desugar {
     // prefixed by type or val). `tparams` and `vparamss` are the type parameters that
     // go in `constr`, the constructor after desugaring.
 
+    /** Does `tree' look like a reference to AnyVal? Temporary test before we have inline classes */
+    def isAnyVal(tree: Tree): Boolean = tree match {
+      case Ident(tpnme.AnyVal) => true
+      case Select(qual, tpnme.AnyVal) => isScala(qual)
+      case _ => false
+    }
+    def isScala(tree: Tree): Boolean = tree match {
+      case Ident(nme.scala_) => true
+      case Select(Ident(nme.ROOTPKG), nme.scala_) => true
+      case _ => false
+    }
+
     val isCaseClass = mods.is(Case) && !mods.is(Module)
+    val isValueClass = parents.nonEmpty && isAnyVal(parents.head)
+      // This is not watertight, but `extends AnyVal` will be replaced by `inline` later.
 
     val constrTparams = constr1.tparams map toDefParam
     val constrVparamss =
@@ -398,7 +412,9 @@ object desugar {
         companionDefs(parent, applyMeths ::: unapplyMeth :: defaultGetters)
       }
       else if (defaultGetters.nonEmpty)
-          companionDefs(anyRef, defaultGetters)
+        companionDefs(anyRef, defaultGetters)
+      else if (isValueClass)
+        companionDefs(anyRef, Nil)
       else Nil
 
 

src/dotty/tools/dotc/core/NameOps.scala

@@ -116,7 +116,12 @@ object NameOps {
       name.drop(tpnme.hkArgPrefixLength).toString.toInt
 
     def isLambdaTraitName(implicit ctx: Context): Boolean =
-      name.startsWith(tpnme.hkLambdaPrefix)
+      name.isTypeName && name.startsWith(tpnme.hkLambdaPrefix)
+
+    def lambdaTraitVariances(implicit ctx: Context): List[Int] = {
+      val vs = name.drop(tpnme.hkLambdaPrefix.length)
+      vs.toList.map(c => tpnme.varianceSuffixes.indexOf(c) - 1)
+    }
 
     /** If the name ends with $nn where nn are
       * all digits, strip the $ and the digits.
@@ -179,7 +184,13 @@ object NameOps {
      *  an encoded name, e.g. super$$plus$eq. See #765.
      */
     def unexpandedName: N = {
-      val idx = name.lastIndexOfSlice(nme.EXPAND_SEPARATOR)
+      var idx = name.lastIndexOfSlice(nme.EXPAND_SEPARATOR)
+
+      // Hack to make super accessors from traits work. They would otherwise fail because of #765
+      // TODO: drop this once we have more robust name handling
+      if (name.slice(idx - FalseSuperLength, idx) == FalseSuper)
+        idx -= FalseSuper.length
+
       if (idx < 0) name else (name drop (idx + nme.EXPAND_SEPARATOR.length)).asInstanceOf[N]
     }
 
@@ -431,4 +442,7 @@ object NameOps {
       name.dropRight(nme.LAZY_LOCAL.length)
     }
   }
+
+  private final val FalseSuper = "$$super".toTermName
+  private val FalseSuperLength = FalseSuper.length
 }

src/dotty/tools/dotc/core/Names.scala

@@ -37,7 +37,7 @@ object Names {
    */
   abstract class Name extends DotClass
     with PreName
-    with Seq[Char]
+    with collection.immutable.Seq[Char]
     with IndexedSeqOptimized[Char, Name] {
 
     /** A type for names of the same kind as this name */

src/dotty/tools/dotc/core/TypeApplications.scala

@@ -377,6 +377,14 @@ class TypeApplications(val self: Type) extends AnyVal {
       false
   }
 
+  /** Dealias type if it can be done without forcing anything */
+  def safeDealias(implicit ctx: Context): Type = self match {
+    case self: TypeRef if self.denot.exists && self.symbol.isAliasType =>
+      self.info.bounds.hi.stripTypeVar.safeDealias
+    case _ =>
+      self
+  }
+
   /** Replace references to type parameters with references to hk arguments `this.$hk_i`
    * Care is needed not to cause cyclic reference errors, hence `SafeSubstMap`.
    */
@@ -546,8 +554,8 @@ class TypeApplications(val self: Type) extends AnyVal {
         substHkArgs(body)
       case self: PolyType =>
         self.instantiate(args)
-      case _ =>
-        appliedTo(args, typeParams)
+      case self1 =>
+        self1.safeDealias.appliedTo(args, typeParams)
     }
   }
 

src/dotty/tools/dotc/core/Types.scala

@@ -903,7 +903,9 @@ object Types {
         case pre: RefinedType =>
           object instantiate extends TypeMap {
             var isSafe = true
-            def apply(tp: Type): Type = tp match {
+            def apply(tp: Type): Type =
+              if (!isSafe) tp
+              else tp match {
               case TypeRef(RefinedThis(`pre`), name) if name.isHkArgName =>
                 member(name).info match {
                   case TypeAlias(alias) => alias
@@ -2061,7 +2063,7 @@ object Types {
         false
     }
     override def computeHash = doHash(refinedName, refinedInfo, parent)
-    override def toString = s"RefinedType($parent, $refinedName, $refinedInfo)"
+    override def toString = s"RefinedType($parent, $refinedName, $refinedInfo | $hashCode)"
   }
 
   class CachedRefinedType(parent: Type, refinedName: Name, infoFn: RefinedType => Type) extends RefinedType(parent, refinedName) {

src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -252,6 +252,8 @@ class TreeUnpickler(reader: TastyReader, tastyName: TastyName.Table) {
           readPackageRef().termRef
         case TYPEREF =>
           val name =  readName().toTypeName
+          if (name.isLambdaTraitName) // Make sure curresponding lambda trait exists
+            defn.LambdaTrait(name.lambdaTraitVariances)
           TypeRef(readType(), name)
         case TERMREF =>
           readNameSplitSig() match {

src/dotty/tools/dotc/transform/ExtensionMethods.scala

@@ -33,7 +33,7 @@ import SymUtils._
  * This is different from the implementation of value classes in Scala 2
  * (see SIP-15) which uses `asInstanceOf` which does not typecheck.
  */
-class ExtensionMethods extends MiniPhaseTransform with DenotTransformer with FullParameterization with NeedsCompanions { thisTransformer =>
+class ExtensionMethods extends MiniPhaseTransform with DenotTransformer with FullParameterization { thisTransformer =>
 
   import tpd._
   import ExtensionMethods._
@@ -45,10 +45,6 @@ class ExtensionMethods extends MiniPhaseTransform with DenotTransformer with Ful
 
   override def runsAfterGroupsOf = Set(classOf[FirstTransform]) // need companion objects to exist
 
-  def isCompanionNeeded(cls: ClassSymbol)(implicit ctx: Context): Boolean = {
-    isDerivedValueClass(cls)
-  }
-
   override def transform(ref: SingleDenotation)(implicit ctx: Context): SingleDenotation = ref match {
     case moduleClassSym: ClassDenotation if moduleClassSym is ModuleClass =>
       moduleClassSym.linkedClass match {

src/dotty/tools/dotc/transform/FirstTransform.scala

@@ -44,7 +44,7 @@ class FirstTransform extends MiniPhaseTransform with IdentityDenotTransformer wi
     this
   }
 
-  def transformInfo(tp: Type, sym: Symbol)(implicit ctx: Context): Type = {
+  def transformInfo(tp: Type, sym: Symbol)(implicit ctx: Context): Type = tp/*{
       tp match {
         //create companions for value classes that are not from currently compiled source file
         case tp@ClassInfo(_, cls, _, decls, _)
@@ -59,7 +59,7 @@ class FirstTransform extends MiniPhaseTransform with IdentityDenotTransformer wi
         case _ => tp
       }
   }
-
+*/
   override def checkPostCondition(tree: Tree)(implicit ctx: Context): Unit = {
     tree match {
       case Select(qual, _) if tree.symbol.exists =>

src/dotty/tools/dotc/transform/SyntheticMethods.scala

@@ -10,6 +10,7 @@ import DenotTransformers._
 import ast.Trees._
 import ast.untpd
 import Decorators._
+import NameOps._
 import ValueClasses.isDerivedValueClass
 import scala.collection.mutable.ListBuffer
 import scala.language.postfixOps
@@ -79,14 +80,17 @@ class SyntheticMethods(thisTransformer: DenotTransformer) {
       def forwardToRuntime(vrefss: List[List[Tree]]): Tree =
         ref(defn.runtimeMethodRef("_" + sym.name.toString)).appliedToArgs(This(clazz) :: vrefss.head)
 
+      def ownName(vrefss: List[List[Tree]]): Tree =
+        Literal(Constant(clazz.name.stripModuleClassSuffix.decode.toString))
+
       def syntheticRHS(implicit ctx: Context): List[List[Tree]] => Tree = synthetic.name match {
         case nme.hashCode_ if isDerivedValueClass(clazz) => vrefss => valueHashCodeBody
         case nme.hashCode_ => vrefss => caseHashCodeBody
-        case nme.toString_ => forwardToRuntime
+        case nme.toString_ => if (clazz.is(ModuleClass)) ownName else forwardToRuntime
         case nme.equals_ => vrefss => equalsBody(vrefss.head.head)
         case nme.canEqual_ => vrefss => canEqualBody(vrefss.head.head)
         case nme.productArity => vrefss => Literal(Constant(accessors.length))
-        case nme.productPrefix => vrefss => Literal(Constant(clazz.name.decode.toString))
+        case nme.productPrefix => ownName
       }
       ctx.log(s"adding $synthetic to $clazz at ${ctx.phase}")
       DefDef(synthetic, syntheticRHS(ctx.withOwner(synthetic)))

src/strawman/collections/CollectionStrawMan4.scala

@@ -2,6 +2,8 @@ package strawman.collections
 
 import Predef.{augmentString => _, wrapString => _, _}
 import scala.reflect.ClassTag
+import annotation.unchecked.uncheckedVariance
+import annotation.tailrec
 
 /** A strawman architecture for new collections. It contains some
  *  example collection classes and methods with the intent to expose
@@ -20,14 +22,7 @@ object CollectionStrawMan4 {
     def iterator: Iterator[A]
   }
 
-  /** Base trait for generic collections */
-  trait Iterable[+A] extends IterableOnce[A] with FromIterable[Iterable] {
-    def iterator: Iterator[A]
-    def view: View[A] = View.fromIterator(iterator)
-    def knownLength: Int = -1
-  }
-
-  /** Base trait for instances that can construct a collection from an iterator */
+  /** Base trait for instances that can construct a collection from an iterable */
   trait FromIterable[+C[X] <: Iterable[X]] {
     def fromIterable[B](v: Iterable[B]): C[B]
   }
@@ -38,16 +33,27 @@ object CollectionStrawMan4 {
     def apply[A](xs: A*): C[A] = fromIterable(View.Elems(xs: _*))
   }
 
+  /** Base trait for generic collections */
+  trait Iterable[+A] extends IterableOnce[A] with FromIterable[Iterable] {
+    def view: View[A] = View.fromIterator(iterator) // view is overridden, cannot be defined in ops
+    def knownLength: Int = -1
+  }
+
   /** Base trait for sequence collections */
   trait Seq[+A] extends Iterable[A] with FromIterable[Seq] {
     def apply(i: Int): A
     def length: Int
   }
 
+  /** Base trait for collection builders */
   trait Builder[-A, +To] {
     def +=(x: A): this.type
-    def ++=(xs: IterableOnce[A]): Unit = xs.iterator.foreach(+=)
     def result: To
+
+    def ++=(xs: IterableOnce[A]): this.type = {
+      xs.iterator.foreach(+=)
+      this
+    }
   }
 
   /* ------------ Operations ----------------------------------- */
@@ -134,17 +140,18 @@ object CollectionStrawMan4 {
       require(!isEmpty)
       if (i == 0) head else tail.apply(i - 1)
     }
-    def :::[B >: A](prefix: List[B]): List[B] =
-      if (prefix.isEmpty) this
-      else Cons(prefix.head, prefix.tail ::: this)
     def length: Int =
       if (isEmpty) 0 else 1 + tail.length
+    def ++:[B >: A](prefix: List[B]): List[B] =
+      if (prefix.isEmpty) this
+      else Cons(prefix.head, prefix.tail ++: this)
   }
 
-  case class Cons[+A](x: A, xs: List[A]) extends List[A] {
+  case class Cons[+A](x: A, private[collections] var next: List[A @uncheckedVariance]) // sound because `next` is used only locally
+  extends List[A] {
     def isEmpty = false
     def head = x
-    def tail = xs
+    def tail = next
   }
 
   case object Nil extends List[Nothing] {
@@ -157,20 +164,64 @@ object CollectionStrawMan4 {
     def fromIterator[B](it: Iterator[B]): List[B] =
       if (it.hasNext) Cons(it.next, fromIterator(it)) else Nil
     def fromIterable[B](c: Iterable[B]): List[B] = c match {
-      case View.Concat(xs, ys: Iterable[B]) =>
-        fromIterable(xs) ::: fromIterable(ys)
+      case View.Concat(xs, ys: List[B]) =>
+        fromIterable(xs) ++: ys
       case View.Drop(xs: List[B], n) =>
-        var i = 0
-        var ys = xs
-        while (i < n && !xs.isEmpty) {
-          ys = ys.tail
-          i += 1
-        }
-        ys
+        @tailrec def loop(xs: List[B], n: Int): List[B] =
+          if (n > 0) loop(xs.tail, n - 1) else xs
+        loop(xs, n)
+      case c: List[B] => c
       case _ => fromIterator(c.iterator)
     }
   }
 
+  /** Concrete collection type: ListBuffer */
+  class ListBuffer[A] extends Seq[A] with FromIterable[ListBuffer] with Builder[A, List[A]] {
+    private var first, last: List[A] = Nil
+    private var aliased = false
+    def iterator = first.iterator
+    def fromIterable[B](coll: Iterable[B]) = ListBuffer.fromIterable(coll)
+    def apply(i: Int) = first.apply(i)
+    def length = first.length
+
+    private def copyElems(): Unit = {
+      val buf = ListBuffer.fromIterable(result)
+      first = buf.first
+      last = buf.last
+      aliased = false
+    }
+    def result = {
+      aliased = true
+      first
+    }
+    def +=(elem: A) = {
+      if (aliased) copyElems()
+      val last1 = Cons(elem, Nil)
+      last match {
+        case last: Cons[A] => last.next = last1
+        case _ => first = last1
+      }
+      last = last1
+      this
+    }
+    override def toString: String =
+      if (first.isEmpty) "ListBuffer()"
+      else {
+        val b = new StringBuilder("ListBuffer(").append(first.head)
+        first.tail.foldLeft(b)(_.append(", ").append(_)).append(")").toString
+      }
+  }
+
+  object ListBuffer extends IterableFactory[ListBuffer] {
+    def fromIterable[B](coll: Iterable[B]): ListBuffer[B] = coll match {
+      case pd @ View.Partitioned(partition: View.Partition[B]) =>
+        partition.distribute(new ListBuffer[B]())
+        pd.forced.get.asInstanceOf[ListBuffer[B]]
+      case _ =>
+        new ListBuffer[B] ++= coll
+    }
+  }
+
   /** Concrete collection type: ArrayBuffer */
   class ArrayBuffer[A] private (initElems: Array[AnyRef], initLength: Int)
   extends Seq[A] with FromIterable[ArrayBuffer] with Builder[A, ArrayBuffer[A]] {
@@ -234,12 +285,6 @@ object CollectionStrawMan4 {
     def apply(n: Int) = elems(start + n).asInstanceOf[A]
   }
 
-  case class StringView(s: String) extends RandomAccessView[Char] {
-    val start = 0
-    val end = s.length
-    def apply(n: Int) = s.charAt(n)
-  }
-
   /** Concrete collection type: String */
   implicit class StringOps(val s: String) extends AnyVal with Ops[Char] {
     def iterator: Iterator[Char] = new StringView(s).iterator
@@ -277,6 +322,12 @@ object CollectionStrawMan4 {
     def ++(xs: String): String = s + xs
   }
 
+  case class StringView(s: String) extends RandomAccessView[Char] {
+    val start = 0
+    val end = s.length
+    def apply(n: Int) = s.charAt(n)
+  }
+
   /* ------------ Views --------------------------------------- */
 
   /** A lazy iterable */
@@ -322,6 +373,8 @@ object CollectionStrawMan4 {
     }
     case class Partition[A](val underlying: Iterable[A], p: A => Boolean) {
       val left, right = Partitioned(this)
+      // `distribute` makes up for the lack of generic push-based functionality.
+      // It forces both halves of the partition with a given builder.
       def distribute(bf: => Builder[A, Iterable[A]]) = {
         val lb, rb = bf
         val it = underlying.iterator