Cleanup of implicit modifiers scheme

Implicit modifiers were quite irregular compared
to the other ones. This commit does a cleanup.

Author: odersky

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

@@ -115,7 +115,7 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
 
     case class Var() extends Mod(Flags.Mutable)
 
-    case class Implicit(flag: FlagSet = Flags.ImplicitCommon) extends Mod(flag)
+    case class Implicit() extends Mod(Flags.ImplicitCommon)
 
     case class Final() extends Mod(Flags.Final)
 

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

@@ -119,7 +119,7 @@ object Comments {
     def apply(comment: Comment, code: String, codePos: Position)(implicit ctx: Context) =
       new UseCase(comment, code, codePos) {
         val untpdCode = {
-          val tree = new Parser(new SourceFile("<usecase>", code)).localDef(codePos.start, EmptyFlags)
+          val tree = new Parser(new SourceFile("<usecase>", code)).localDef(codePos.start)
 
           tree match {
             case tree: untpd.DefDef =>

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -1063,7 +1063,7 @@ object Parsers {
       case FOR =>
         forExpr()
       case IMPLICIT =>
-        implicitClosure(in.skipToken(), location)
+        implicitClosure(in.offset, location, atPos(in.skipToken()) { Mod.Implicit() })
       case _ =>
         expr1Rest(postfixExpr(), location)
     }
@@ -1114,9 +1114,8 @@ object Parsers {
     /** Expr         ::= implicit Id `=>' Expr
      *  BlockResult  ::= implicit Id [`:' InfixType] `=>' Block
      */
-    def implicitClosure(start: Int, location: Location.Value, implicitMod: Option[Mod] = None): Tree = {
-      var mods = atPos(start) { Modifiers(Implicit) }
-      if (implicitMod.nonEmpty) mods = mods.withAddedMod(implicitMod.get)
+    def implicitClosure(start: Int, location: Location.Value, implicitMod: Mod): Tree = {
+      val mods = Modifiers(Implicit).withAddedMod(implicitMod)
       val id = termIdent()
       val paramExpr =
         if (location == Location.InBlock && in.token == COLON)
@@ -1485,7 +1484,7 @@ object Parsers {
     private def modOfToken(tok: Int): Mod = tok match {
       case ABSTRACT  => Mod.Abstract()
       case FINAL     => Mod.Final()
-      case IMPLICIT  => Mod.Implicit(ImplicitCommon)
+      case IMPLICIT  => Mod.Implicit()
       case INLINE    => Mod.Inline()
       case LAZY      => Mod.Lazy()
       case OVERRIDE  => Mod.Override()
@@ -1741,7 +1740,7 @@ object Parsers {
         else {
           if (in.token == IMPLICIT) {
             implicitOffset = in.offset
-            implicitMod = atPos(in.skipToken()) { Mod.Implicit(Implicit) }
+            implicitMod = atPos(in.skipToken()) { Mod.Implicit() }
           }
           commaSeparated(param)
         }
@@ -2214,9 +2213,9 @@ object Parsers {
       stats.toList
     }
 
-    def localDef(start: Int, implicitFlag: FlagSet, implicitMod: Option[Mod] = None): Tree = {
-      var mods = addFlag(defAnnotsMods(localModifierTokens), implicitFlag)
-      if (implicitMod.nonEmpty) mods = mods.withAddedMod(implicitMod.get)
+    def localDef(start: Int, implicitMod: Option[Mod] = None): Tree = {
+      var mods = defAnnotsMods(localModifierTokens)
+      for (imod <- implicitMod) mods = (mods | ImplicitCommon).withAddedMod(imod)
       defOrDcl(start, mods)
     }
 
@@ -2239,11 +2238,11 @@ object Parsers {
         else if (isDefIntro(localModifierTokens))
           if (in.token == IMPLICIT) {
             val start = in.offset
-            val mod = atPos(in.skipToken()) { Mod.Implicit(ImplicitCommon) }
-            if (isIdent) stats += implicitClosure(start, Location.InBlock, Some(mod))
-            else stats += localDef(start, ImplicitCommon, Some(mod))
+            val mod = atPos(in.skipToken()) { Mod.Implicit() }
+            if (isIdent) stats += implicitClosure(start, Location.InBlock, mod)
+            else stats += localDef(start, Some(mod))
           } else {
-            stats += localDef(in.offset, EmptyFlags)
+            stats += localDef(in.offset)
           }
         else if (!isStatSep && (in.token != CASE)) {
           exitOnError = mustStartStat

compiler/test/dotty/tools/dotc/parsing/ModifiersParsingTest.scala

@@ -140,12 +140,12 @@ class ModifiersParsingTest {
 
     source = "def f(implicit a: Int, b: Int) = ???"
     println(source.defParam(0).modifiers)
-    assert(source.defParam(0).modifiers == List(Mod.Implicit(Flags.Implicit)))
-    assert(source.defParam(1).modifiers == List(Mod.Implicit(Flags.Implicit)))
+    assert(source.defParam(0).modifiers == List(Mod.Implicit()))
+    assert(source.defParam(1).modifiers == List(Mod.Implicit()))
 
     source = "def f(x: Int, y: Int)(implicit a: Int, b: Int) = ???"
     assert(source.defParam(0, 0).modifiers == List())
-    assert(source.defParam(1, 0).modifiers == List(Mod.Implicit(Flags.Implicit)))
+    assert(source.defParam(1, 0).modifiers == List(Mod.Implicit()))
   }
 
   @Test def blockDef = {