Fix/#646 array addition

src/dotty/DottyPredef.scala

@@ -4,22 +4,34 @@ import scala.reflect.ClassTag
 import scala.reflect.runtime.universe.TypeTag
 import scala.Predef.???  // this is currently ineffective, because of #530
 
-object DottyPredef {
-  /** implicits for ClassTag and TypeTag. Should be implemented with macros */
+abstract class I1 {
   implicit def classTag[T]: ClassTag[T] = scala.Predef.???
   implicit def typeTag[T]: TypeTag[T] = scala.Predef.???
-
-
-  /** ClassTags for final classes */
+  implicit val DoubleClassTag: ClassTag[Double]   = ClassTag.Double
+}
+abstract class I2 extends I1 {
+  implicit val FloatClassTag: ClassTag[Double]   = ClassTag.Double
+}
+abstract class I3 extends I2 {
+  implicit val LongClassTag: ClassTag[Long]       = ClassTag.Long
+}
+abstract class I4 extends I3 {
   implicit val IntClassTag: ClassTag[Int]         = ClassTag.Int
-  implicit val ByteClassTag: ClassTag[Byte]       = ClassTag.Byte
+}
+abstract class I5 extends I4 {
   implicit val ShortClassTag: ClassTag[Short]     = ClassTag.Short
+}
+abstract class I6 extends I5 {
+  implicit val ByteClassTag: ClassTag[Byte]       = ClassTag.Byte
   implicit val CharClassTag: ClassTag[Char]       = ClassTag.Char
-  implicit val LongClassTag: ClassTag[Long]       = ClassTag.Long
-  implicit val FloatClassTag: ClassTag[Float]     = ClassTag.Float
-  implicit val DoubleClassTag: ClassTag[Double]   = ClassTag.Double
   implicit val BooleanClassTag: ClassTag[Boolean] = ClassTag.Boolean
   implicit val UnitClassTag: ClassTag[Unit]       = ClassTag.Unit
   implicit val NullClassTag: ClassTag[Null]       = ClassTag.Null
+}
+
+/** implicits for ClassTag and TypeTag. Should be implemented with macros */
+object DottyPredef extends I6 {
+
+  /** ClassTags for final classes */
   implicit val NothingClassTag: ClassTag[Nothing] = ClassTag.Nothing
 }

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

@@ -386,13 +386,6 @@ object Contexts {
     final def withOwner(owner: Symbol): Context =
       if (owner ne this.owner) fresh.setOwner(owner) else this
 
-    final def withMode(mode: Mode): Context =
-      if (mode != this.mode) fresh.setMode(mode) else this
-
-    final def addMode(mode: Mode): Context = withMode(this.mode | mode)
-    final def maskMode(mode: Mode): Context = withMode(this.mode & mode)
-    final def retractMode(mode: Mode): Context = withMode(this.mode &~ mode)
-
     override def toString =
       "Context(\n" +
       (outersIterator map ( ctx => s"  owner = ${ctx.owner}, scope = ${ctx.scope}") mkString "\n")
@@ -444,6 +437,21 @@ object Contexts {
     def setDebug = setSetting(base.settings.debug, true)
   }
 
+  implicit class ModeChanges(val c: Context) extends AnyVal {
+    final def withMode(mode: Mode): Context =
+      if (mode != c.mode) c.fresh.setMode(mode) else c
+
+    final def addMode(mode: Mode): Context = withMode(c.mode | mode)
+    final def maskMode(mode: Mode): Context = withMode(c.mode & mode)
+    final def retractMode(mode: Mode): Context = withMode(c.mode &~ mode)
+  }
+
+  implicit class FreshModeChanges(val c: FreshContext) extends AnyVal {
+    final def addMode(mode: Mode): c.type = c.setMode(c.mode | mode)
+    final def maskMode(mode: Mode): c.type = c.setMode(c.mode & mode)
+    final def retractMode(mode: Mode): c.type = c.setMode(c.mode &~ mode)
+  }
+
   /** A class defining the initial context with given context base
    *  and set of possible settings.
    */

src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -12,7 +12,7 @@ import typer.Mode
 import scala.annotation.switch
 
 class PlainPrinter(_ctx: Context) extends Printer {
-  protected[this] implicit def ctx: Context = _ctx.fresh.addMode(Mode.Printing)
+  protected[this] implicit def ctx: Context = _ctx.addMode(Mode.Printing)
 
   protected def maxToTextRecursions = 100
 

src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -148,7 +148,8 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       case JavaArrayType(elemtp) =>
         return toText(elemtp) ~ "[]"
       case tp: SelectionProto =>
-        return "?{ " ~ toText(tp.name) ~ ": " ~ toText(tp.memberProto) ~ " }"
+        return "?{ " ~ toText(tp.name) ~ (" " provided !tp.name.decode.last.isLetterOrDigit) ~
+          ": " ~ toText(tp.memberProto) ~ " }"
       case tp: ViewProto =>
         return toText(tp.argType) ~ " ?=>? " ~ toText(tp.resultType)
       case tp @ FunProto(args, resultType, _) =>

src/dotty/tools/dotc/typer/Implicits.scala

@@ -90,7 +90,7 @@ object Implicits {
       }
 
       if (refs.isEmpty) refs
-      else refs filter (refMatches(_)(ctx.fresh.setExploreTyperState.addMode(Mode.TypevarsMissContext))) // create a defensive copy of ctx to avoid constraint pollution
+      else refs filter (refMatches(_)(ctx.fresh.addMode(Mode.TypevarsMissContext).setExploreTyperState)) // create a defensive copy of ctx to avoid constraint pollution
     }
   }
 
@@ -384,7 +384,9 @@ trait Implicits { self: Typer =>
     && (ctx.mode is Mode.ImplicitsEnabled)
     && from.isInstanceOf[ValueType]
     && (  from.isValueSubType(to)
-       || inferView(dummyTreeOfType(from), to)(ctx.fresh.setExploreTyperState).isInstanceOf[SearchSuccess]
+       || inferView(dummyTreeOfType(from), to)
+            (ctx.fresh.addMode(Mode.ImplicitExploration).setExploreTyperState)
+            .isInstanceOf[SearchSuccess]
        )
     )
 
@@ -480,7 +482,8 @@ trait Implicits { self: Typer =>
             pt)
         val generated1 = adapt(generated, pt)
         lazy val shadowing =
-          typed(untpd.Ident(ref.name) withPos pos.toSynthetic, funProto)(nestedContext.setNewTyperState.addMode(Mode.ImplicitShadowing))
+          typed(untpd.Ident(ref.name) withPos pos.toSynthetic, funProto)
+               (nestedContext.addMode(Mode.ImplicitShadowing).setNewTyperState)
         def refMatches(shadowing: Tree): Boolean =
           ref.symbol == closureBody(shadowing).symbol || {
             shadowing match {
@@ -514,8 +517,11 @@ trait Implicits { self: Typer =>
             case fail: SearchFailure =>
               rankImplicits(pending1, acc)
             case best: SearchSuccess =>
-              val newPending = pending1 filter (isAsGood(_, best.ref)(nestedContext.setExploreTyperState))
-              rankImplicits(newPending, best :: acc)
+              if (ctx.mode.is(Mode.ImplicitExploration)) best :: Nil
+              else {
+                val newPending = pending1 filter (isAsGood(_, best.ref)(nestedContext.setExploreTyperState))
+                rankImplicits(newPending, best :: acc)
+              }
           }
         case nil => acc
       }

src/dotty/tools/dotc/typer/Mode.scala

@@ -73,5 +73,11 @@ object Mode {
    */
   val ImplicitShadowing = newMode(11, "ImplicitShadowing")
 
+  /** We are currently in a `viewExists` check. In that case, ambiguous
+   *  implicits checks are disabled and we succeed with the first implicit
+   *  found.
+   */
+  val ImplicitExploration = newMode(12, "ImplicitExploration")
+
   val PatternOrType = Pattern | Type
 }

src/dotty/tools/dotc/typer/Namer.scala

@@ -701,7 +701,7 @@ class Namer { typer: Typer =>
 
       // println(s"final inherited for $sym: ${inherited.toString}") !!!
       // println(s"owner = ${sym.owner}, decls = ${sym.owner.info.decls.show}")
-      val rhsCtx = ctx.fresh addMode Mode.InferringReturnType
+      val rhsCtx = ctx.addMode(Mode.InferringReturnType)
       def rhsType = ctx.deskolemize(
         typedAheadExpr(mdef.rhs, rhsProto)(rhsCtx).tpe.widen.approximateUnion)
       def lhsType = fullyDefinedType(rhsType, "right-hand side", mdef.pos)