Drop Config.checkKinds

Allows us to drop also the involved knownHK method. Lots of other
cleanups.

13 files changed, 20 insertions, 107 deletions

diff --git a/src/dotty/tools/dotc/config/Config.scala b/src/dotty/tools/dotc/config/Config.scala
index 796a2e693..3cc3091b5 100644
--- a/src/dotty/tools/dotc/config/Config.scala
+++ b/src/dotty/tools/dotc/config/Config.scala
@@ -77,13 +77,6 @@ object Config {
    */
   final val checkProjections = false
 
-  /** If this flag is set, it is checked that &/| only apply to types
-   *  that are either both hk types or both * types. Should be used
-   *  only for debugging as the assertion may be violated by Implicits.liftToClasses,
-   *  which can produce an And over a generic class without arguments.
-   */
-  final val checkKinds = false
-
   /** The recursion depth for showing a summarized string */
   final val summarizeDepth = 2
 
diff --git a/src/dotty/tools/dotc/core/TypeApplications.scala b/src/dotty/tools/dotc/core/TypeApplications.scala
index 94ca7a3ac..580cd6569 100644
--- a/src/dotty/tools/dotc/core/TypeApplications.scala
+++ b/src/dotty/tools/dotc/core/TypeApplications.scala
@@ -209,7 +209,7 @@ class TypeApplications(val self: Type) extends AnyVal {
     }
   }
 
-  /** If `self` is a higher-kinded type, its type parameters $hk_i, otherwise Nil */
+  /** If `self` is a higher-kinded type, its type parameters, otherwise Nil */
   final def hkTypeParams(implicit ctx: Context): List[TypeParamInfo] =
     if (isHK) typeParams else Nil
 
@@ -295,57 +295,10 @@ class TypeApplications(val self: Type) extends AnyVal {
     case _ => false
   }
 
-  /** Computes the kind of `self` without forcing anything.
-   *  @return   1   if type is known to be higher-kinded
-   *           -1   if type is known to be a * type
-   *            0   if kind of `self` is unknown (because symbols have not yet completed)
-   */
-  def knownHK(implicit ctx: Context): Int = self match {
-    case self: TypeRef =>
-      val tsym = self.symbol
-      if (tsym.isClass) -1
-      else tsym.infoOrCompleter match {
-        case completer: TypeParamsCompleter =>
-          if (completer.completerTypeParams(tsym).nonEmpty) 1 else -1
-        case _ =>
-          if (!tsym.isCompleting || tsym.isAliasType) tsym.info.knownHK
-          else 0
-      }
-    case self: RefinedType => -1
-    case self: TypeLambda => 1
-    case self: HKApply => -1
-    case self: SingletonType => -1
-    case self: TypeVar => self.origin.knownHK
-    case self: WildcardType => self.optBounds.knownHK
-    case self: TypeProxy => self.underlying.knownHK
-    case NoType | _: LazyType => 0
-    case _ => -1
-  }
-
-  /** True if it can be determined without forcing that the class symbol
-   *  of this application exists. Equivalent to
-   *
-   *    self.classSymbol.exists
-   *
-   *  but without forcing anything.
-   */
-  def safeIsClassRef(implicit ctx: Context): Boolean = self.stripTypeVar match {
-    case self: RefinedOrRecType =>
-      self.parent.safeIsClassRef
-    case self: TypeRef =>
-      self.denot.exists && {
-        val sym = self.symbol
-        sym.isClass ||
-        sym.isCompleted && self.info.isAlias
-      }
-    case _ =>
-      false
-  }
-
   /** Dealias type if it can be done without forcing the TypeRef's info */
   def safeDealias(implicit ctx: Context): Type = self match {
     case self: TypeRef if self.denot.exists && self.symbol.isAliasType =>
-      self.info.bounds.hi.stripTypeVar.safeDealias
+      self.superType.stripTypeVar.safeDealias
     case _ =>
       self
   }
@@ -389,14 +342,6 @@ class TypeApplications(val self: Type) extends AnyVal {
       //.ensuring(res => res.EtaReduce =:= self, s"res = $res, core = ${res.EtaReduce}, self = $self, hc = ${res.hashCode}")
   }
 
-  /** Eta expand the prefix in front of any refinements. */
-  def EtaExpandCore(implicit ctx: Context): Type = self.stripTypeVar match {
-    case self: RefinedType =>
-      self.derivedRefinedType(self.parent.EtaExpandCore, self.refinedName, self.refinedInfo)
-    case _ =>
-      self.EtaExpand(self.typeParamSymbols)
-  }
-
   /** If self is not higher-kinded, eta expand it. */
   def ensureHK(implicit ctx: Context): Type =
     if (isHK) self else EtaExpansion(self)
@@ -566,7 +511,8 @@ class TypeApplications(val self: Type) extends AnyVal {
    */
   final def baseArgInfos(base: Symbol)(implicit ctx: Context): List[Type] =
     if (self derivesFrom base)
-      self match {
+      self.dealias match {
+        case self: TypeRef if !self.symbol.isClass => self.superType.baseArgInfos(base)
         case self: HKApply => self.superType.baseArgInfos(base)
         case _ => base.typeParams.map(param => self.member(param.name).info.argInfo)
       }
@@ -591,17 +537,6 @@ class TypeApplications(val self: Type) extends AnyVal {
   final def baseArgTypesHi(base: Symbol)(implicit ctx: Context): List[Type] =
     baseArgInfos(base) mapConserve boundsToHi
 
-  /** The first type argument of the base type instance wrt `base` of this type */
-  final def firstBaseArgInfo(base: Symbol)(implicit ctx: Context): Type = base.typeParams match {
-    case param :: _ if self derivesFrom base =>
-      self match {
-        case self: HKApply => self.superType.firstBaseArgInfo(base)
-        case _ => self.member(param.name).info.argInfo
-      }
-    case _ =>
-      NoType
-  }
-
   /** The base type including all type arguments and applicable refinements
    *  of this type. Refinements are applicable if they refine a member of
    *  the parent type which furthermore is not a name-mangled type parameter.
@@ -711,6 +646,6 @@ class TypeApplications(val self: Type) extends AnyVal {
   def elemType(implicit ctx: Context): Type = self match {
     case defn.ArrayOf(elemtp) => elemtp
     case JavaArrayType(elemtp) => elemtp
-    case _ => firstBaseArgInfo(defn.SeqClass)
+    case _ => baseArgInfos(defn.SeqClass).headOption.getOrElse(NoType)
   }
 }
diff --git a/src/dotty/tools/dotc/core/TypeComparer.scala b/src/dotty/tools/dotc/core/TypeComparer.scala
index 34fe8629e..d310bd844 100644
--- a/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -1353,7 +1353,7 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling {
       case _ => tp.show
     }
     if (true) throw new MergeError(s"cannot merge ${showType(tp1)} with ${showType(tp2)}", tp1, tp2)
-    else throw new Error(s"cannot merge ${showType(tp1)} with ${showType(tp2)}")
+    else throw new Error(s"cannot merge ${showType(tp1)} with ${showType(tp2)}") // flip condition for debugging
   }
 
   /** Merge two lists of names. If names in corresponding positions match, keep them,
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index 85c8fd623..786c74069 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -1744,7 +1744,7 @@ object Types {
     type ThisType = TypeRef
 
     override def underlying(implicit ctx: Context): Type = info
-    
+
     override def superType(implicit ctx: Context): Type = info match {
       case TypeBounds(_, hi) => hi
       case _ => info
@@ -2203,8 +2203,6 @@ object Types {
   object AndType {
     def apply(tp1: Type, tp2: Type)(implicit ctx: Context) = {
       assert(tp1.isInstanceOf[ValueType] && tp2.isInstanceOf[ValueType], i"$tp1 & $tp2 / " + s"$tp1 & $tp2")
-      if (Config.checkKinds)
-        assert((tp1.knownHK - tp2.knownHK).abs <= 1, i"$tp1 & $tp2 / " + s"$tp1 & $tp2")
       unchecked(tp1, tp2)
     }
     def unchecked(tp1: Type, tp2: Type)(implicit ctx: Context) = {
@@ -2239,7 +2237,6 @@ object Types {
   object OrType {
     def apply(tp1: Type, tp2: Type)(implicit ctx: Context) = {
       assertUnerased()
-      if (Config.checkKinds) assert((tp1.knownHK - tp2.knownHK).abs <= 1, i"$tp1 | $tp2")
       unique(new CachedOrType(tp1, tp2))
     }
     def make(tp1: Type, tp2: Type)(implicit ctx: Context): Type =
diff --git a/src/dotty/tools/dotc/core/tasty/TastyFormat.scala b/src/dotty/tools/dotc/core/tasty/TastyFormat.scala
index d9006eda9..394d8f11a 100644
--- a/src/dotty/tools/dotc/core/tasty/TastyFormat.scala
+++ b/src/dotty/tools/dotc/core/tasty/TastyFormat.scala
@@ -499,7 +499,6 @@ object TastyFormat {
          SELFDEF | REFINEDtype => 1
     case RENAMED | PARAMtype => 2
     case POLYtype | METHODtype => -1
-    case TYPEBOUNDS => -2
     case _ => 0
   }
 
diff --git a/src/dotty/tools/dotc/core/tasty/TreePickler.scala b/src/dotty/tools/dotc/core/tasty/TreePickler.scala
index a4fdb2751..be3999533 100644
--- a/src/dotty/tools/dotc/core/tasty/TreePickler.scala
+++ b/src/dotty/tools/dotc/core/tasty/TreePickler.scala
@@ -158,7 +158,7 @@ class TreePickler(pickler: TastyPickler) {
     case ConstantType(value) =>
       pickleConstant(value)
     case tpe: TypeRef if tpe.info.isAlias && tpe.symbol.is(Flags.AliasPreferred) =>
-      pickleType(tpe.info.bounds.hi)
+      pickleType(tpe.superType)
     case tpe: WithFixedSym =>
       val sym = tpe.symbol
       def pickleRef() =
@@ -240,10 +240,7 @@ class TreePickler(pickler: TastyPickler) {
       }
     case tpe: TypeBounds =>
       writeByte(TYPEBOUNDS)
-      withLength {
-        pickleType(tpe.lo, richTypes)
-        pickleType(tpe.hi, richTypes)
-      }
+      withLength { pickleType(tpe.lo, richTypes); pickleType(tpe.hi, richTypes) }
     case tpe: AnnotatedType =>
       writeByte(ANNOTATED)
       withLength { pickleType(tpe.tpe, richTypes); pickleTree(tpe.annot.tree) }
diff --git a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
index 1da92d723..e8f3d63a9 100644
--- a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
+++ b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
@@ -135,13 +135,6 @@ object Scala2Unpickler {
     denot.info = ClassInfo( // final info, except possibly for typeparams ordering
       denot.owner.thisType, denot.classSymbol, parentRefs, decls, ost)
     denot.updateTypeParams(tparams)
-
-    // Curiously the following line is needed to make pos/i859.scala compile.
-    // This test simply accesses scala.tools.nsc.Global. I could not track down why
-    // the reference is needed - referencing any field of the type parameter
-    // does the trick, no completion is needed (in fact such completion would
-    // cause cyclic references elsewhere).
-    assert(denot.typeParams.forall(_.exists))
   }
 }
 
@@ -593,7 +586,7 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
       val tag = readByte()
       val end = readNat() + readIndex
       if (tag == POLYtpe) {
-        val unusedRestperef = readNat()
+        val unusedRestpeRef = readNat()
         until(end, readSymbolRef).asInstanceOf[List[TypeSymbol]]
       } else Nil
     }
diff --git a/src/dotty/tools/dotc/transform/ElimRepeated.scala b/src/dotty/tools/dotc/transform/ElimRepeated.scala
index 30778267d..258b7f234 100644
--- a/src/dotty/tools/dotc/transform/ElimRepeated.scala
+++ b/src/dotty/tools/dotc/transform/ElimRepeated.scala
@@ -74,7 +74,7 @@ class ElimRepeated extends MiniPhaseTransform with InfoTransformer with Annotati
     case SeqLiteral(elems, elemtpt) =>
       JavaSeqLiteral(elems, elemtpt)
     case _ =>
-      val elemType = tree.tpe.firstBaseArgInfo(defn.SeqClass)
+      val elemType = tree.tpe.elemType
       var elemClass = elemType.classSymbol
       if (defn.PhantomClasses contains elemClass) elemClass = defn.ObjectClass
       ref(defn.DottyArraysModule)
diff --git a/src/dotty/tools/dotc/transform/PostTyper.scala b/src/dotty/tools/dotc/transform/PostTyper.scala
index 057026a67..b71284049 100644
--- a/src/dotty/tools/dotc/transform/PostTyper.scala
+++ b/src/dotty/tools/dotc/transform/PostTyper.scala
@@ -13,6 +13,7 @@ import Types._, Contexts._, Constants._, Names._, NameOps._, Flags._, DenotTrans
 import SymDenotations._, Symbols._, StdNames._, Annotations._, Trees._, Scopes._, Denotations._
 import util.Positions._
 import Decorators._
+import config.Printers._
 import Symbols._, TypeUtils._
 
 /** A macro transform that runs immediately after typer and that performs the following functions:
@@ -121,7 +122,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
    */
   private def fixSignature[T <: Tree](tree: T)(implicit ctx: Context): T = tree.tpe match {
     case tpe: TermRefWithSignature if tpe.signature.isUnderDefined =>
-      println(i"fixing $tree with type ${tree.tpe.widen.toString} with sig ${tpe.signature} to ${tpe.widen.signature}")
+      typr.println(i"fixing $tree with type ${tree.tpe.widen.toString} with sig ${tpe.signature} to ${tpe.widen.signature}")
       tree.withType(TermRef.withSig(tpe.prefix, tpe.name, tpe.widen.signature)).asInstanceOf[T]
     case _ => tree
   }
diff --git a/src/dotty/tools/dotc/typer/Applications.scala b/src/dotty/tools/dotc/typer/Applications.scala
index caae422d3..aba073f3d 100644
--- a/src/dotty/tools/dotc/typer/Applications.scala
+++ b/src/dotty/tools/dotc/typer/Applications.scala
@@ -67,7 +67,7 @@ object Applications {
     if (extractorMemberType(unapplyResult, nme.isDefined, pos) isRef defn.BooleanClass) {
       if (getTp.exists)
         if (unapplyFn.symbol.name == nme.unapplySeq) {
-          val seqArg = boundsToHi(getTp.firstBaseArgInfo(defn.SeqClass))
+          val seqArg = boundsToHi(getTp.elemType)
           if (seqArg.exists) return args map Function.const(seqArg)
         }
         else return getUnapplySelectors(getTp, args, pos)
@@ -629,7 +629,7 @@ trait Applications extends Compatibility { self: Typer =>
 
   def typedTypeApply(tree: untpd.TypeApply, pt: Type)(implicit ctx: Context): Tree = track("typedTypeApply") {
     val isNamed = hasNamedArg(tree.args)
-    var typedArgs = if (isNamed) typedNamedArgs(tree.args) else tree.args.mapconserve(typedType(_))
+    val typedArgs = if (isNamed) typedNamedArgs(tree.args) else tree.args.mapconserve(typedType(_))
     val typedFn = typedExpr(tree.fun, PolyProto(typedArgs.tpes, pt))
     typedFn.tpe.widen match {
       case pt: PolyType =>
diff --git a/src/dotty/tools/dotc/typer/Checking.scala b/src/dotty/tools/dotc/typer/Checking.scala
index e77222beb..3aa63aeeb 100644
--- a/src/dotty/tools/dotc/typer/Checking.scala
+++ b/src/dotty/tools/dotc/typer/Checking.scala
@@ -34,7 +34,8 @@ object Checking {
   import tpd._
 
   /** A general checkBounds method that can be used for TypeApply nodes as
-   *  well as for AppliedTypeTree nodes.
+   *  well as for AppliedTypeTree nodes. Also checks that type arguments to
+   *  *-type parameters are fully applied.
    */
   def checkBounds(args: List[tpd.Tree], boundss: List[TypeBounds], instantiate: (Type, List[Type]) => Type)(implicit ctx: Context) = {
     (args, boundss).zipped.foreach { (arg, bound) =>
@@ -223,9 +224,6 @@ object Checking {
     val checker = new CheckNonCyclicMap(sym, reportErrors)(ctx.addMode(Mode.CheckCyclic))
     try checker.checkInfo(info)
     catch {
-          case ex: AssertionError =>
-            println(s"assertion error for $info")
-            throw ex
       case ex: CyclicReference =>
         if (reportErrors) {
           ctx.error(i"illegal cyclic reference: ${checker.where} ${checker.lastChecked} of $sym refers back to the type itself", sym.pos)
@@ -364,7 +362,7 @@ object Checking {
             // try to dealias to avoid a leak error
             val savedErrors = errors
             errors = prevErrors
-            val tp2 = apply(tp.info.bounds.hi)
+            val tp2 = apply(tp.superType)
             if (errors eq prevErrors) tp1 = tp2
             else errors = savedErrors
           }
diff --git a/src/dotty/tools/dotc/typer/Implicits.scala b/src/dotty/tools/dotc/typer/Implicits.scala
index 91a67de9a..feed398aa 100644
--- a/src/dotty/tools/dotc/typer/Implicits.scala
+++ b/src/dotty/tools/dotc/typer/Implicits.scala
@@ -772,7 +772,7 @@ class SearchHistory(val searchDepth: Int, val seen: Map[ClassSymbol, Int]) {
         case tp: RefinedType =>
           foldOver(n + 1, tp)
         case tp: TypeRef if tp.info.isAlias =>
-          apply(n, tp.info.bounds.hi)
+          apply(n, tp.superType)
         case _ =>
           foldOver(n, tp)
       }
diff --git a/src/dotty/tools/dotc/typer/Inferencing.scala b/src/dotty/tools/dotc/typer/Inferencing.scala
index e024192c3..c60f4c1f2 100644
--- a/src/dotty/tools/dotc/typer/Inferencing.scala
+++ b/src/dotty/tools/dotc/typer/Inferencing.scala
@@ -176,7 +176,7 @@ object Inferencing {
   /** Recursively widen and also follow type declarations and type aliases. */
   def widenForMatchSelector(tp: Type)(implicit ctx: Context): Type = tp.widen match {
     case tp: TypeRef if !tp.symbol.isClass =>
-      widenForMatchSelector(tp.info.bounds.hi)
+      widenForMatchSelector(tp.superType)
     case tp: HKApply =>
       widenForMatchSelector(tp.superType)
     case tp: AnnotatedType =>