Rename unused to ghost

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -80,7 +80,7 @@ class Compiler {
          new ShortcutImplicits,      // Allow implicit functions without creating closures
          new CrossCastAnd,           // Normalize selections involving intersection types.
          new Splitter) ::            // Expand selections involving union types into conditionals
-    List(new UnusedDecls,            // Removes all unused defs and vals decls (except for parameters)
+    List(new GhostDecls,             // Removes all ghost defs and vals decls (except for parameters)
          new VCInlineMethods,        // Inlines calls to value class methods
          new SeqLiterals,            // Express vararg arguments as arrays
          new InterceptedMethods,     // Special handling of `==`, `|=`, `getClass` methods

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

@@ -262,7 +262,7 @@ object desugar {
   private def toDefParam(tparam: TypeDef): TypeDef =
     tparam.withMods(tparam.rawMods & EmptyFlags | Param)
   private def toDefParam(vparam: ValDef): ValDef =
-    vparam.withMods(vparam.rawMods & (Implicit | Unused) | Param)
+    vparam.withMods(vparam.rawMods & (Implicit | Ghost) | Param)
 
   /** The expansion of a class definition. See inline comments for what is involved */
   def classDef(cdef: TypeDef)(implicit ctx: Context): Tree = {

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -396,7 +396,7 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
    *               flags set.
    */
   private def refPurity(tree: Tree)(implicit ctx: Context): PurityLevel =
-    if (!tree.tpe.widen.isParameterless || tree.symbol.is(Unused)) SimplyPure
+    if (!tree.tpe.widen.isParameterless || tree.symbol.is(Ghost)) SimplyPure
     else if (!tree.symbol.isStable) Impure
     else if (tree.symbol.is(Lazy)) Idempotent // TODO add Module flag, sinxce Module vals or not Lazy from the start.
     else SimplyPure

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -202,8 +202,8 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       case tp: MethodType =>
         def valueParam(name: TermName, info: Type): TermSymbol = {
           val maybeImplicit = if (tp.isImplicitMethod) Implicit else EmptyFlags
-          val maybeUnused = if (tp.isUnusedMethod) Unused else EmptyFlags
-          ctx.newSymbol(sym, name, TermParam | maybeImplicit | maybeUnused, info, coord = sym.coord)
+          val maybeGhost = if (tp.isGhostMethod) Ghost else EmptyFlags
+          ctx.newSymbol(sym, name, TermParam | maybeImplicit | maybeGhost, info, coord = sym.coord)
         }
         val params = (tp.paramNames, tp.paramInfos).zipped.map(valueParam)
         val (paramss, rtp) = valueParamss(tp.instantiate(params map (_.termRef)))

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -118,7 +118,7 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
 
     case class Implicit() extends Mod(Flags.ImplicitCommon)
 
-    case class Unused() extends Mod(Flags.Unused)
+    case class Ghost() extends Mod(Flags.Ghost)
 
     case class Final() extends Mod(Flags.Final)
 

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

@@ -88,7 +88,7 @@ class Definitions {
     newClassSymbol(ScalaPackageClass, name, EmptyFlags, completer).entered
   }
 
-  /** The trait FunctionN, ImplicitFunctionN, UnusedFunctionN or UnusedImplicitFunction, for some N
+  /** The trait FunctionN, ImplicitFunctionN, GhostFunctionN or GhostImplicitFunction, for some N
    *  @param  name   The name of the trait to be created
    *
    *  FunctionN traits follow this template:
@@ -107,19 +107,19 @@ class Definitions {
    *        def apply(implicit $x0: T0, ..., $x{N_1}: T{N-1}): R
    *      }
    *
-   *  UnusedFunctionN traits follow this template:
+   *  GhostFunctionN traits follow this template:
    *
-   *      trait UnusedFunctionN[T0,...,T{N-1}, R] extends Object {
-   *        def apply(unused $x0: T0, ..., $x{N_1}: T{N-1}): R
+   *      trait GhostFunctionN[T0,...,T{N-1}, R] extends Object {
+   *        def apply(ghost $x0: T0, ..., $x{N_1}: T{N-1}): R
    *      }
    *
-   *  UnusedImplicitFunctionN traits follow this template:
+   *  GhostImplicitFunctionN traits follow this template:
    *
-   *      trait UnusedImplicitFunctionN[T0,...,T{N-1}, R] extends Object with UnusedFunctionN[T0,...,T{N-1}, R] {
-   *        def apply(unused implicit $x0: T0, ..., $x{N_1}: T{N-1}): R
+   *      trait GhostImplicitFunctionN[T0,...,T{N-1}, R] extends Object with GhostFunctionN[T0,...,T{N-1}, R] {
+   *        def apply(ghost implicit $x0: T0, ..., $x{N_1}: T{N-1}): R
    *      }
    *
-   *  UnusedFunctionN and UnusedImplicitFunctionN erase to Function0.
+   *  GhostFunctionN and GhostImplicitFunctionN erase to Function0.
    */
   def newFunctionNTrait(name: TypeName): ClassSymbol = {
     val completer = new LazyType {
@@ -132,10 +132,10 @@ class Definitions {
           enterTypeParam(cls, paramNamePrefix ++ "T" ++ (i + 1).toString, Contravariant, decls).typeRef
         }
         val resParamRef = enterTypeParam(cls, paramNamePrefix ++ "R", Covariant, decls).typeRef
-        val methodType = MethodType.maker(isJava = false, name.isImplicitFunction, name.isUnusedFunction)
+        val methodType = MethodType.maker(isJava = false, name.isImplicitFunction, name.isGhostFunction)
         val parentTraits =
           if (!name.isImplicitFunction) Nil
-          else FunctionType(arity, isUnused = name.isUnusedFunction).appliedTo(argParamRefs ::: resParamRef :: Nil) :: Nil
+          else FunctionType(arity, isGhost = name.isGhostFunction).appliedTo(argParamRefs ::: resParamRef :: Nil) :: Nil
         decls.enter(newMethod(cls, nme.apply, methodType(argParamRefs, resParamRef), Deferred))
         denot.info =
           ClassInfo(ScalaPackageClass.thisType, cls, ObjectType :: parentTraits, decls)
@@ -756,14 +756,14 @@ class Definitions {
     sym.owner.linkedClass.typeRef
 
   object FunctionOf {
-    def apply(args: List[Type], resultType: Type, isImplicit: Boolean = false, isUnused: Boolean = false)(implicit ctx: Context) =
-      FunctionType(args.length, isImplicit, isUnused).appliedTo(args ::: resultType :: Nil)
+    def apply(args: List[Type], resultType: Type, isImplicit: Boolean = false, isGhost: Boolean = false)(implicit ctx: Context) =
+      FunctionType(args.length, isImplicit, isGhost).appliedTo(args ::: resultType :: Nil)
     def unapply(ft: Type)(implicit ctx: Context) = {
       val tsym = ft.typeSymbol
       if (isFunctionClass(tsym)) {
         val targs = ft.dealias.argInfos
         if (targs.isEmpty) None
-        else Some(targs.init, targs.last, tsym.name.isImplicitFunction, tsym.name.isUnusedFunction)
+        else Some(targs.init, targs.last, tsym.name.isImplicitFunction, tsym.name.isGhostFunction)
       }
       else None
     }
@@ -827,18 +827,18 @@ class Definitions {
 
   lazy val TupleType = mkArityArray("scala.Tuple", MaxTupleArity, 2)
 
-  def FunctionClass(n: Int, isImplicit: Boolean = false, isUnused: Boolean = false)(implicit ctx: Context) = {
-    if (isImplicit && isUnused) {
+  def FunctionClass(n: Int, isImplicit: Boolean = false, isGhost: Boolean = false)(implicit ctx: Context) = {
+    if (isImplicit && isGhost) {
       require(n > 0)
-      ctx.requiredClass("scala.UnusedImplicitFunction" + n.toString)
+      ctx.requiredClass("scala.GhostImplicitFunction" + n.toString)
     }
     else if (isImplicit) {
       require(n > 0)
       ctx.requiredClass("scala.ImplicitFunction" + n.toString)
     }
-    else if (isUnused) {
+    else if (isGhost) {
       require(n > 0)
-      ctx.requiredClass("scala.UnusedFunction" + n.toString)
+      ctx.requiredClass("scala.GhostFunction" + n.toString)
     }
     else if (n <= MaxImplementedFunctionArity) FunctionClassPerRun()(ctx)(n)
     else ctx.requiredClass("scala.Function" + n.toString)
@@ -847,9 +847,9 @@ class Definitions {
     lazy val Function0_applyR = ImplementedFunctionType(0).symbol.requiredMethodRef(nme.apply)
     def Function0_apply(implicit ctx: Context) = Function0_applyR.symbol
 
-  def FunctionType(n: Int, isImplicit: Boolean = false, isUnused: Boolean = false)(implicit ctx: Context): TypeRef =
-    if (n <= MaxImplementedFunctionArity && (!isImplicit || ctx.erasedTypes) && !isUnused) ImplementedFunctionType(n)
-    else FunctionClass(n, isImplicit, isUnused).typeRef
+  def FunctionType(n: Int, isImplicit: Boolean = false, isGhost: Boolean = false)(implicit ctx: Context): TypeRef =
+    if (n <= MaxImplementedFunctionArity && (!isImplicit || ctx.erasedTypes) && !isGhost) ImplementedFunctionType(n)
+    else FunctionClass(n, isImplicit, isGhost).typeRef
 
   private lazy val TupleTypes: Set[TypeRef] = TupleType.toSet
 
@@ -874,22 +874,22 @@ class Definitions {
   /** Is a function class.
    *   - FunctionN for N >= 0
    *   - ImplicitFunctionN for N > 0
-   *   - UnusedFunctionN for N > 0
-   *   - UnusedImplicitFunctionN for N > 0
+   *   - GhostFunctionN for N > 0
+   *   - GhostImplicitFunctionN for N > 0
    */
   def isFunctionClass(cls: Symbol) = scalaClassName(cls).isFunction
 
   /** Is an implicit function class.
    *   - ImplicitFunctionN for N > 0
-   *   - UnusedImplicitFunctionN for N > 0
+   *   - GhostImplicitFunctionN for N > 0
    */
   def isImplicitFunctionClass(cls: Symbol) = scalaClassName(cls).isImplicitFunction
 
-  /** Is an unused function class.
-   *   - UnusedFunctionN for N > 0
-   *   - UnusedImplicitFunctionN for N > 0
+  /** Is an ghost function class.
+   *   - GhostFunctionN for N > 0
+   *   - GhostImplicitFunctionN for N > 0
    */
-  def isUnusedFunctionClass(cls: Symbol) = scalaClassName(cls).isUnusedFunction
+  def isGhostFunctionClass(cls: Symbol) = scalaClassName(cls).isGhostFunction
 
   /** Is a class that will be erased to FunctionXXL
    *   - FunctionN for N >= 22
@@ -915,13 +915,13 @@ class Definitions {
    *    - FunctionN for 22 > N >= 0 remains as FunctionN
    *    - ImplicitFunctionN for N > 22 becomes FunctionXXL
    *    - ImplicitFunctionN for 22 > N >= 0 becomes FunctionN
-   *    - UnusedFunctionN becomes Function0
-   *    - ImplicitUnusedFunctionN becomes Function0
+   *    - GhostFunctionN becomes Function0
+   *    - ImplicitGhostFunctionN becomes Function0
    *    - anything else becomes a NoSymbol
    */
   def erasedFunctionClass(cls: Symbol): Symbol = {
     val arity = scalaClassName(cls).functionArity
-    if (cls.name.isUnusedFunction) FunctionClass(0)
+    if (cls.name.isGhostFunction) FunctionClass(0)
     else if (arity > 22) FunctionXXLClass
     else if (arity >= 0) FunctionClass(arity)
     else NoSymbol
@@ -932,13 +932,13 @@ class Definitions {
    *    - FunctionN for 22 > N >= 0 remains as FunctionN
    *    - ImplicitFunctionN for N > 22 becomes FunctionXXL
    *    - ImplicitFunctionN for 22 > N >= 0 becomes FunctionN
-   *    - UnusedFunctionN becomes Function0
-   *    - ImplicitUnusedFunctionN becomes Function0
+   *    - GhostFunctionN becomes Function0
+   *    - ImplicitGhostFunctionN becomes Function0
    *    - anything else becomes a NoType
    */
   def erasedFunctionType(cls: Symbol): Type = {
     val arity = scalaClassName(cls).functionArity
-    if (cls.name.isUnusedFunction) FunctionType(0)
+    if (cls.name.isGhostFunction) FunctionType(0)
     else if (arity > 22) FunctionXXLType
     else if (arity >= 0) FunctionType(arity)
     else NoType
@@ -1008,7 +1008,7 @@ class Definitions {
   def isNonDepFunctionType(tp: Type)(implicit ctx: Context) = {
     val arity = functionArity(tp)
     val sym = tp.dealias.typeSymbol
-    arity >= 0 && isFunctionClass(sym) && tp.isRef(FunctionType(arity, sym.name.isImplicitFunction, sym.name.isUnusedFunction).typeSymbol)
+    arity >= 0 && isFunctionClass(sym) && tp.isRef(FunctionType(arity, sym.name.isImplicitFunction, sym.name.isGhostFunction).typeSymbol)
   }
 
   /** Is `tp` a representation of a (possibly depenent) function type or an alias of such? */
@@ -1074,8 +1074,8 @@ class Definitions {
   def isImplicitFunctionType(tp: Type)(implicit ctx: Context): Boolean =
     asImplicitFunctionType(tp).exists
 
-  def isUnusedFunctionType(tp: Type)(implicit ctx: Context) =
-    isFunctionType(tp) && tp.dealias.typeSymbol.name.isUnusedFunction
+  def isGhostFunctionType(tp: Type)(implicit ctx: Context) =
+    isFunctionType(tp) && tp.dealias.typeSymbol.name.isGhostFunction
 
   // ----- primitive value class machinery ------------------------------------------
 

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

@@ -367,8 +367,8 @@ object Flags {
   /** Symbol is a Java enum */
   final val Enum = commonFlag(40, "<enum>")
 
-  /** Labeled with `unused` modifier (unused value)  */
-  final val Unused = termFlag(42, "unused")
+  /** Labeled with `ghost` modifier (ghost value)  */
+  final val Ghost = termFlag(42, "ghost")
 
   // Flags following this one are not pickled
 
@@ -441,7 +441,7 @@ object Flags {
   /** Flags representing source modifiers */
   final val SourceModifierFlags =
     commonFlags(Private, Protected, Abstract, Final, Inline,
-     Sealed, Case, Implicit, Override, AbsOverride, Lazy, JavaStatic, Unused)
+     Sealed, Case, Implicit, Override, AbsOverride, Lazy, JavaStatic, Ghost)
 
   /** Flags representing modifiers that can appear in trees */
   final val ModifierFlags =
@@ -515,7 +515,7 @@ object Flags {
   /** Flags that can apply to a module val */
   final val RetainedModuleValFlags: FlagSet = RetainedModuleValAndClassFlags |
     Override | Final | Method | Implicit | Lazy |
-    Accessor | AbsOverride | Stable | Captured | Synchronized | Inline | Unused
+    Accessor | AbsOverride | Stable | Captured | Synchronized | Inline | Ghost
 
   /** Flags that can apply to a module class */
   final val RetainedModuleClassFlags: FlagSet = RetainedModuleValAndClassFlags | ImplClass | Enum

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

@@ -176,51 +176,51 @@ object NameOps {
       functionArityFor(str.Function) max {
         val n =
           functionArityFor(str.ImplicitFunction) max
-          functionArityFor(str.UnusedFunction) max
-          functionArityFor(str.UnusedImplicitFunction)
+          functionArityFor(str.GhostFunction) max
+          functionArityFor(str.GhostImplicitFunction)
         if (n == 0) -1 else n
       }
 
     /** Is a function name
      *    - FunctionN for N >= 0
      *    - ImplicitFunctionN for N >= 1
-     *    - UnusedFunctionN for N >= 1
-     *    - UnusedImplicitFunctionN for N >= 1
+     *    - GhostFunctionN for N >= 1
+     *    - GhostImplicitFunctionN for N >= 1
      *    - false otherwise
      */
     def isFunction: Boolean = functionArity >= 0
 
     /** Is a implicit function name
      *    - ImplicitFunctionN for N >= 1
-     *    - UnusedImplicitFunctionN for N >= 1
+     *    - GhostImplicitFunctionN for N >= 1
      *    - false otherwise
      */
     def isImplicitFunction: Boolean = {
       functionArityFor(str.ImplicitFunction) >= 1 ||
-      functionArityFor(str.UnusedImplicitFunction) >= 1
+      functionArityFor(str.GhostImplicitFunction) >= 1
     }
 
     /** Is a implicit function name
-      *    - UnusedFunctionN for N >= 1
-      *    - UnusedImplicitFunctionN for N >= 1
+      *    - GhostFunctionN for N >= 1
+      *    - GhostImplicitFunctionN for N >= 1
       *    - false otherwise
       */
-    def isUnusedFunction: Boolean = {
-      functionArityFor(str.UnusedFunction) >= 1 ||
-      functionArityFor(str.UnusedImplicitFunction) >= 1
+    def isGhostFunction: Boolean = {
+      functionArityFor(str.GhostFunction) >= 1 ||
+      functionArityFor(str.GhostImplicitFunction) >= 1
     }
 
     /** Is a synthetic function name
      *    - FunctionN for N > 22
      *    - ImplicitFunctionN for N >= 1
-     *    - UnusedFunctionN for N >= 1
-     *    - UnusedImplicitFunctionN for N >= 1
+     *    - GhostFunctionN for N >= 1
+     *    - GhostImplicitFunctionN for N >= 1
      *    - false otherwise
      */
     def isSyntheticFunction: Boolean = {
       functionArityFor(str.Function) > MaxImplementedFunctionArity ||
       functionArityFor(str.ImplicitFunction) >= 1 ||
-      isUnusedFunction
+      isGhostFunction
     }
 
     /** Parsed function arity for function with some specific prefix */

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

@@ -36,9 +36,9 @@ object StdNames {
     final val MODULE_INSTANCE_FIELD      = "MODULE$"
 
     final val Function                   = "Function"
-    final val UnusedFunction             = "UnusedFunction"
+    final val GhostFunction              = "GhostFunction"
     final val ImplicitFunction           = "ImplicitFunction"
-    final val UnusedImplicitFunction     = "UnusedImplicitFunction"
+    final val GhostImplicitFunction      = "GhostImplicitFunction"
     final val AbstractFunction           = "AbstractFunction"
     final val Tuple                      = "Tuple"
     final val Product                    = "Product"

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

@@ -399,7 +399,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
     case tp: MethodType =>
       def paramErasure(tpToErase: Type) =
         erasureFn(tp.isJavaMethod, semiEraseVCs, isConstructor, wildcardOK)(tpToErase)
-      val (names, formals0) = if (tp.isUnusedMethod) (Nil, Nil) else (tp.paramNames, tp.paramInfos)
+      val (names, formals0) = if (tp.isGhostMethod) (Nil, Nil) else (tp.paramNames, tp.paramInfos)
       val formals = formals0.mapConserve(paramErasure)
       eraseResult(tp.resultType) match {
         case rt: MethodType =>