More robust way to refer to private definitions in types

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

@@ -342,10 +342,10 @@ object Denotations {
       def mergeDenot(denot1: Denotation, denot2: SingleDenotation): Denotation = denot1 match {
         case denot1 @ MultiDenotation(denot11, denot12) =>
           val d1 = mergeDenot(denot11, denot2)
-          if (d1.exists) denot1.derivedMultiDenotation(d1, denot12)
+          if (d1.exists) denot1.derivedUnionDenotation(d1, denot12)
           else {
             val d2 = mergeDenot(denot12, denot2)
-            if (d2.exists) denot1.derivedMultiDenotation(denot11, d2)
+            if (d2.exists) denot1.derivedUnionDenotation(denot11, d2)
             else NoDenotation
           }
         case denot1: SingleDenotation =>
@@ -532,11 +532,11 @@ object Denotations {
       else if (!that.exists) that
       else this match {
         case denot1 @ MultiDenotation(denot11, denot12) =>
-          denot1.derivedMultiDenotation(denot11 | (that, pre), denot12 | (that, pre))
+          denot1.derivedUnionDenotation(denot11 | (that, pre), denot12 | (that, pre))
         case denot1: SingleDenotation =>
           that match {
             case denot2 @ MultiDenotation(denot21, denot22) =>
-              denot2.derivedMultiDenotation(this | (denot21, pre), this | (denot22, pre))
+              denot2.derivedUnionDenotation(this | (denot21, pre), this | (denot22, pre))
             case denot2: SingleDenotation =>
               unionDenot(denot1, denot2)
           }
@@ -558,9 +558,10 @@ object Denotations {
     final def isType = false
     final def signature(implicit ctx: Context) = Signature.OverloadedSignature
     def atSignature(sig: Signature, site: Type, relaxed: Boolean)(implicit ctx: Context): Denotation =
-      derivedMultiDenotation(denot1.atSignature(sig, site, relaxed), denot2.atSignature(sig, site, relaxed))
+      if (sig eq Signature.OverloadedSignature) this
+      else derivedUnionDenotation(denot1.atSignature(sig, site, relaxed), denot2.atSignature(sig, site, relaxed))
     def current(implicit ctx: Context): Denotation =
-      derivedMultiDenotation(denot1.current, denot2.current)
+      derivedUnionDenotation(denot1.current, denot2.current)
     def altsWith(p: Symbol => Boolean): List[SingleDenotation] =
       denot1.altsWith(p) ++ denot2.altsWith(p)
     def suchThat(p: Symbol => Boolean)(implicit ctx: Context): SingleDenotation = {
@@ -580,12 +581,15 @@ object Denotations {
       val d2 = denot2 accessibleFrom (pre, superAccess)
       if (!d1.exists) d2
       else if (!d2.exists) d1
-      else derivedMultiDenotation(d1, d2)
+      else derivedUnionDenotation(d1, d2)
     }
     def mapInfo(f: Type => Type)(implicit ctx: Context): Denotation =
-      derivedMultiDenotation(denot1.mapInfo(f), denot2.mapInfo(f))
-    def derivedMultiDenotation(d1: Denotation, d2: Denotation) =
-      if ((d1 eq denot1) && (d2 eq denot2)) this else MultiDenotation(d1, d2)
+      derivedUnionDenotation(denot1.mapInfo(f), denot2.mapInfo(f))
+    def derivedUnionDenotation(d1: Denotation, d2: Denotation): Denotation =
+      if ((d1 eq denot1) && (d2 eq denot2)) this
+      else if (!d1.exists) d2
+      else if (!d2.exists) d1
+      else MultiDenotation(d1, d2)
     override def toString = alternatives.mkString(" <and> ")
 
     private def multiHasNot(op: String): Nothing =

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

@@ -3,14 +3,17 @@ package dotc
 package core
 
 import Names._
+import NameKinds.SignedName
+import Types.{TypeRef, NameSpace, noNameSpace}
+import Symbols.Symbol
 import Contexts.Context
 
 /** Defines a common superclass of Name and Symbol and its Term/Type variants
  *  Designators are used in reference type to identity what is referred to.
  */
 object Designators {
 
-  abstract class Designator extends util.DotClass {
+  abstract class Designator extends util.DotClass { self =>
 
     type ThisName <: Name
 
@@ -23,8 +26,53 @@ object Designators {
 
     def asTerm(implicit ctx: Context): TermDesignator = unsupported("asTerm")
     def asType(implicit ctx: Context): TypeDesignator = unsupported("asType")
+
+    def withNameSpace(space: NameSpace)(implicit ctx: Context): Designator { type ThisName = self.ThisName } =
+      if (space == noNameSpace) this
+      else localName(this.asInstanceOf[ThisName], space)
+
+    /** Localize this name to the owner of `sym` if `sym` is private */
+    def localizeIfPrivate(sym: Symbol)(implicit ctx: Context): Designator { type ThisName = self.ThisName } =
+      if (sym.isPrivate) withNameSpace(sym.owner.typeRef) else this
+
+    def withSig(sig: Signature): Designator{ type ThisName = TermName } = {
+      val unsigned = this.asInstanceOf[TermName].exclude(SignedName)
+      if (sig eq Signature.NotAMethod) unsigned else SignedName(unsigned, sig)
+    }
   }
 
   type TermDesignator = Designator { type ThisName = TermName }
   type TypeDesignator = Designator { type ThisName = TypeName }
+
+  /** Names that come with the namespace where they are defined.
+   *  Used to give a stable reference to private names, and also to
+   *  Scala 2x inner classes.
+   */
+  case class LocalName[N <: Name](name: N, nameSpace: TypeRef) extends Designator {
+    type ThisName = N
+
+    override def isTerm(implicit ctx: Context) = name.isTermName
+    override def isType(implicit ctx: Context) = name.isTypeName
+
+    override def asTerm(implicit ctx: Context): TermDesignator = {
+      name.asTermName
+      this.asInstanceOf[TermDesignator]
+    }
+    override def asType(implicit ctx: Context): TypeDesignator = {
+      name.asTypeName
+      this.asInstanceOf[TypeDesignator]
+    }
+
+    override def withNameSpace(space: NameSpace)(implicit ctx: Context) =
+      name.withNameSpace(space).asInstanceOf[Designator { type ThisName = N }]
+
+    override def withSig(sig: Signature) =
+      LocalName(name.withSig(sig).asInstanceOf[TermName], nameSpace)
+  }
+
+  /** Introduced to overcome shortcoming with refined type inference of case classes:
+   *  LocalName's result type is always Designator, without a refinement.
+   */
+  def localName[N <: Name](name: N, nameSpace: TypeRef): Designator { type ThisName = N } =
+    LocalName(name, nameSpace).asInstanceOf[Designator { type ThisName = N }]
 }

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

@@ -54,7 +54,8 @@ object NameKinds {
     def unmangle(name: SimpleName): TermName = name
 
     /** Turn a name of this kind consisting of an `underlying` prefix
-     *  and the given `info` into a string.
+     *  and the given `info` into a string. Used to turn structured into
+     *  simple name.
      */
     def mkString(underlying: TermName, info: ThisInfo): String
 
@@ -120,7 +121,7 @@ object NameKinds {
   class QualifiedNameKind(tag: Int, val separator: String)
   extends NameKind(tag) {
     type ThisInfo = QualInfo
-    case class QualInfo(val name: SimpleName) extends Info with QualifiedInfo {
+    case class QualInfo(name: SimpleName) extends Info with QualifiedInfo {
       override def map(f: SimpleName => SimpleName): NameInfo = new QualInfo(f(name))
       override def toString = s"$infoString $name"
     }
@@ -349,7 +350,6 @@ object NameKinds {
 
   val SuperAccessorName = new PrefixNameKind(SUPERACCESSOR, "super$")
   val InitializerName = new PrefixNameKind(INITIALIZER, "initial$")
-  val ShadowedName = new PrefixNameKind(SHADOWED, "(shadowed)")
   val ProtectedAccessorName = new PrefixNameKind(PROTECTEDACCESSOR, "protected$")
   val ProtectedSetterName = new PrefixNameKind(PROTECTEDSETTER, "protected$set") // dubious encoding, kept for Scala2 compatibility
   val AvoidClashName = new SuffixNameKind(AVOIDCLASH, "$_avoid_name_clash_$")
@@ -363,9 +363,10 @@ object NameKinds {
   val ImplMethName = new SuffixNameKind(IMPLMETH, "$")
 
   /** A name together with a signature. Used in Tasty trees. */
-  object SignedName extends NameKind(63) {
+  object SignedName extends NameKind(SIGNED) {
 
     case class SignedInfo(sig: Signature) extends Info {
+      assert(sig ne Signature.NotAMethod)
       override def toString = s"$infoString $sig"
     }
     type ThisInfo = SignedInfo

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

@@ -311,7 +311,5 @@ object NameOps {
       case raw.BANG  => UNARY_!
       case _ => name
     }
-
-    def withSig(sig: Signature) = SignedName(name.exclude(SignedName), sig)
   }
 }

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

@@ -21,7 +21,6 @@ object StdNames {
     final val TRAIT_SETTER_SEPARATOR   = "$_setter_$"
     final val SUPER_PREFIX             = "super$"
     final val INITIALIZER_PREFIX       = "initial$"
-    final val SHADOWED_PREFIX          = "(shadowed)"
     final val AVOID_CLASH_SUFFIX       = "$_avoid_name_clash_$"
     final val MODULE_SUFFIX            = "$"
     final val NAME_JOIN                = "$"

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

@@ -295,7 +295,7 @@ trait Substituters { this: Context =>
             fs = fs.tail
             ts = ts.tail
           }
-          tp.newLikeThis(apply(tp.prefix))
+          tp.withPrefix(apply(tp.prefix))
         }
         catch {
           case ex: CyclicReference => tp.derivedSelect(apply(tp.prefix))

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

@@ -394,7 +394,7 @@ object Symbols {
 
     type ThisName <: Name
 
-    //assert(id != 4285)
+    //assert(id != 723)
 
     /** The last denotation of this symbol */
     private[this] var lastDenot: SymDenotation = _
@@ -446,11 +446,23 @@ object Symbols {
     final def isClass: Boolean = isInstanceOf[ClassSymbol]
     final def asClass: ClassSymbol = asInstanceOf[ClassSymbol]
 
+    /** Test whether symbol is referenced symbolically. This
+     *  conservatively returns `false` if symbol does not yet have a denotation
+     */
     final def isReferencedSymbolically(implicit ctx: Context) = {
       val d = lastDenot
       d != null && (d.is(NonMember) || d.isTerm && ctx.phase.symbolicRefs)
     }
 
+    /** Test whether symbol is private. This
+     *  conservatively returns `false` if symbol does not yet have a denotation, or denotation
+     *  is a class that is not yet read.
+     */
+    final def isPrivate(implicit ctx: Context) = {
+      val d = lastDenot
+      d != null && d.flagsUNSAFE.is(Private)
+    }
+
     /** The symbol's signature if it is completed or a method, NotAMethod otherwise. */
     final def signature(implicit ctx: Context) =
       if (lastDenot != null && (lastDenot.isCompleted || lastDenot.is(Method)))
@@ -489,7 +501,7 @@ object Symbols {
           if (this is Module) this.moduleClass.validFor |= InitialPeriod
         }
         else this.owner.asClass.ensureFreshScopeAfter(phase)
-        if (!this.flagsUNSAFE.is(Private))
+        if (!isPrivate)
           assert(phase.changesMembers, i"$this entered in ${this.owner} at undeclared phase $phase")
         entered
       }