Refactor stopAtStatic

Introduce a third boundary for stopping at packages

Author: odersky

compiler/src/dotty/tools/dotc/core/ConstraintHandling.scala

@@ -99,7 +99,7 @@ trait ConstraintHandling {
       val bound = dropWildcards(rawBound)
       val oldBounds @ TypeBounds(lo, hi) = constraint.nonParamBounds(param)
       val equalBounds = (if isUpper then lo else hi) eq bound
-      if equalBounds && !bound.existsPart(_ eq param, stopAtStatic = true) then
+      if equalBounds && !bound.existsPart(_ eq param, StopAt.Static) then
         // The narrowed bounds are equal and not recursive,
         // so we can remove `param` from the constraint.
         constraint = constraint.replace(param, bound)

compiler/src/dotty/tools/dotc/core/TypeComparer.scala

@@ -1391,7 +1391,7 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
      */
     def canCompare(ts: Set[Type]) =
       ctx.phase.isTyper
-      || !ts.exists(_.existsPart(_.isInstanceOf[SkolemType], stopAtStatic = true))
+      || !ts.exists(_.existsPart(_.isInstanceOf[SkolemType], StopAt.Static))
 
     def verified(result: Boolean): Boolean =
       if Config.checkAtomsComparisons then

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

@@ -439,23 +439,23 @@ object Types {
 
     /** Does this type contain wildcard types? */
     final def containsWildcardTypes(using Context) =
-      existsPart(_.isInstanceOf[WildcardType], stopAtStatic = true, forceLazy = false)
+      existsPart(_.isInstanceOf[WildcardType], StopAt.Static, forceLazy = false)
 
 // ----- Higher-order combinators -----------------------------------
 
     /** Returns true if there is a part of this type that satisfies predicate `p`.
      */
-    final def existsPart(p: Type => Boolean, stopAtStatic: Boolean = false, forceLazy: Boolean = true)(using Context): Boolean =
-      new ExistsAccumulator(p, stopAtStatic, forceLazy).apply(false, this)
+    final def existsPart(p: Type => Boolean, stopAt: StopAt = StopAt.None, forceLazy: Boolean = true)(using Context): Boolean =
+      new ExistsAccumulator(p, stopAt, forceLazy).apply(false, this)
 
     /** Returns true if all parts of this type satisfy predicate `p`.
      */
     final def forallParts(p: Type => Boolean)(using Context): Boolean =
       !existsPart(!p(_))
 
     /** Performs operation on all parts of this type */
-    final def foreachPart(p: Type => Unit, stopAtStatic: Boolean = false)(using Context): Unit =
-      new ForeachAccumulator(p, stopAtStatic).apply((), this)
+    final def foreachPart(p: Type => Unit, stopAt: StopAt = StopAt.None)(using Context): Unit =
+      new ForeachAccumulator(p, stopAt).apply((), this)
 
     /** The parts of this type which are type or term refs and which
      *  satisfy predicate `p`.
@@ -5199,6 +5199,12 @@ object Types {
 
   // ----- TypeMaps --------------------------------------------------------------------
 
+  /** Where a traversal should stop */
+  enum StopAt:
+    case None    // traverse everything
+    case Package // stop at package references
+    case Static  // stop at static references
+
   /** Common base class of TypeMap and TypeAccumulator */
   abstract class VariantTraversal:
     protected[core] var variance: Int = 1
@@ -5211,7 +5217,7 @@ object Types {
       res
     }
 
-    protected def stopAtStatic: Boolean = true
+    protected def stopAt: StopAt = StopAt.Static
 
     /** Can the prefix of this static reference be omitted if the reference
      *  itself can be omitted? Overridden in TypeOps#avoid.
@@ -5220,7 +5226,11 @@ object Types {
 
     protected def stopBecauseStaticOrLocal(tp: NamedType)(using Context): Boolean =
       (tp.prefix eq NoPrefix)
-      || stopAtStatic && tp.currentSymbol.isStatic && isStaticPrefix(tp.prefix)
+      || {
+        val stop = stopAt
+        stop == StopAt.Static && tp.currentSymbol.isStatic && isStaticPrefix(tp.prefix)
+        || stop == StopAt.Package && tp.currentSymbol.is(Package)
+      }
   end VariantTraversal
 
   abstract class TypeMap(implicit protected var mapCtx: Context)
@@ -5409,7 +5419,7 @@ object Types {
       derivedClassInfo(tp, this(tp.prefix))
 
     def andThen(f: Type => Type): TypeMap = new TypeMap {
-      override def stopAtStatic = thisMap.stopAtStatic
+      override def stopAt = thisMap.stopAt
       def apply(tp: Type) = f(thisMap(tp))
     }
   }
@@ -5831,12 +5841,12 @@ object Types {
 
   class ExistsAccumulator(
       p: Type => Boolean,
-      override val stopAtStatic: Boolean,
+      override val stopAt: StopAt,
       forceLazy: Boolean)(using Context) extends TypeAccumulator[Boolean]:
     def apply(x: Boolean, tp: Type): Boolean =
       x || p(tp) || (forceLazy || !tp.isInstanceOf[LazyRef]) && foldOver(x, tp)
 
-  class ForeachAccumulator(p: Type => Unit, override val stopAtStatic: Boolean)(using Context) extends TypeAccumulator[Unit] {
+  class ForeachAccumulator(p: Type => Unit, override val stopAt: StopAt)(using Context) extends TypeAccumulator[Unit] {
     def apply(x: Unit, tp: Type): Unit = foldOver(p(tp), tp)
   }
 

compiler/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala

@@ -700,7 +700,7 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
     }
     // Cannot use standard `existsPart` method because it calls `lookupRefined`
     // which can cause CyclicReference errors.
-    val isBoundAccumulator = new ExistsAccumulator(isBound, stopAtStatic = true, forceLazy = true):
+    val isBoundAccumulator = new ExistsAccumulator(isBound, StopAt.Static, forceLazy = true):
       override def foldOver(x: Boolean, tp: Type): Boolean = tp match
         case tp: TypeRef => applyToPrefix(x, tp)
         case _ => super.foldOver(x, tp)

compiler/src/dotty/tools/dotc/typer/Checking.scala

@@ -1088,7 +1088,7 @@ trait Checking {
         }
       case _ =>
     }
-    tp.foreachPart(check, stopAtStatic = true)
+    tp.foreachPart(check, StopAt.Static)
     if (ok) tp else UnspecifiedErrorType
   }
 

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

@@ -732,7 +732,7 @@ trait ImplicitRunInfo:
       case null =>
         record(i"implicitScope")
         val liftToAnchors = new TypeMap:
-          override def stopAtStatic = true
+          override def stopAt = StopAt.Static
           private val seen = util.HashSet[Type]()
 
           def applyToUnderlying(t: TypeProxy) =

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -669,7 +669,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(using Context) {
   /** Register type of leaf node */
   private def registerLeaf(tree: Tree): Unit = tree match {
     case _: This | _: Ident | _: TypeTree =>
-      tree.typeOpt.foreachPart(registerType, stopAtStatic = true)
+      tree.typeOpt.foreachPart(registerType, StopAt.Static)
     case _ =>
   }
 

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

@@ -1519,7 +1519,7 @@ class Namer { typer: Typer =>
         approxTp.stripPoly match
           case atp @ defn.ContextFunctionType(_, resType, _)
           if !defn.isNonRefinedFunction(atp) // in this case `resType` is lying, gives us only the non-dependent upper bound
-              || resType.existsPart(_.isInstanceOf[WildcardType], stopAtStatic = true, forceLazy = false) =>
+              || resType.existsPart(_.isInstanceOf[WildcardType], StopAt.Static, forceLazy = false) =>
             originalTp
           case _ =>
             approxTp

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -2803,7 +2803,7 @@ class Typer extends Namer
     // see tests/pos/i7778b.scala
 
     val paramTypes = {
-      val hasWildcard = formals.exists(_.existsPart(_.isInstanceOf[WildcardType], stopAtStatic = true))
+      val hasWildcard = formals.exists(_.existsPart(_.isInstanceOf[WildcardType], StopAt.Static))
       if hasWildcard then formals.map(_ => untpd.TypeTree())
       else formals.map(untpd.TypeTree)
     }