Eliminate redundant "symbol" calls on Symbols.

Everyone of these is a roundtrip `toDenot(stm).symbol`.

Author: odersky

compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala

@@ -842,7 +842,7 @@ class DottyBackendInterface(outputDirectory: AbstractFile, val superCallsMap: Ma
     def superInterfaces: List[Symbol] = {
       val directlyInheritedTraits = decorateSymbol(sym).directlyInheritedTraits
       val directlyInheritedTraitsSet = directlyInheritedTraits.toSet
-      val allBaseClasses = directlyInheritedTraits.iterator.flatMap(_.symbol.asClass.baseClasses.drop(1)).toSet
+      val allBaseClasses = directlyInheritedTraits.iterator.flatMap(_.asClass.baseClasses.drop(1)).toSet
       val superCalls = superCallsMap.getOrElse(sym, Set.empty)
       val additional = (superCalls -- directlyInheritedTraitsSet).filter(_.is(Flags.Trait))
 //      if (additional.nonEmpty)

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

@@ -625,7 +625,7 @@ class Definitions {
     lazy val Product_productPrefixR = ProductClass.requiredMethodRef(nme.productPrefix)
     def Product_productPrefix(implicit ctx: Context) = Product_productPrefixR.symbol
   lazy val LanguageModuleRef = ctx.requiredModule("scala.language")
-  def LanguageModuleClass(implicit ctx: Context) = LanguageModuleRef.symbol.moduleClass.asClass
+  def LanguageModuleClass(implicit ctx: Context) = LanguageModuleRef.moduleClass.asClass
   lazy val NonLocalReturnControlType: TypeRef   = ctx.requiredClassRef("scala.runtime.NonLocalReturnControl")
   lazy val SelectableType: TypeRef              = ctx.requiredClassRef("scala.Selectable")
 
@@ -635,19 +635,13 @@ class Definitions {
 
   lazy val QuotedExprType = ctx.requiredClassRef("scala.quoted.Expr")
   def QuotedExprClass(implicit ctx: Context) = QuotedExprType.symbol.asClass
-
-  lazy val QuotedExprModuleType = ctx.requiredModuleRef("scala.quoted.Expr")
-  def QuotedExprModule(implicit ctx: Context) = QuotedExprModuleType.symbol
+  def QuotedExprModule(implicit ctx: Context) = QuotedExprClass.companionModule
     lazy val QuotedExpr_applyR = QuotedExprModule.requiredMethodRef(nme.apply)
     def QuotedExpr_apply(implicit ctx: Context) = QuotedExpr_applyR.symbol
-
-    lazy val QuotedExpr_spliceR = QuotedExprClass.requiredMethod(nme.UNARY_~)
-    def QuotedExpr_~(implicit ctx: Context) = QuotedExpr_spliceR.symbol
-    lazy val QuotedExpr_runR = QuotedExprClass.requiredMethodRef(nme.run)
-    def QuotedExpr_run(implicit ctx: Context) = QuotedExpr_runR.symbol
+    lazy val QuotedExpr_~ = QuotedExprClass.requiredMethod(nme.UNARY_~)
 
   lazy val QuotedExprsModule = ctx.requiredModule("scala.quoted.Exprs")
-  def QuotedExprsClass(implicit ctx: Context) = QuotedExprsModule.symbol.asClass
+  def QuotedExprsClass(implicit ctx: Context) = QuotedExprsModule.asClass
 
   lazy val QuotedTypeType = ctx.requiredClassRef("scala.quoted.Type")
   def QuotedTypeClass(implicit ctx: Context) = QuotedTypeType.symbol.asClass

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

@@ -580,13 +580,13 @@ object SymDenotations {
       myFlags.is(ModuleClass) && (myFlags.is(PackageClass) || isStatic)
 
     /** Is this denotation defined in the same scope and compilation unit as that symbol? */
-    final def isCoDefinedWith(that: Symbol)(implicit ctx: Context) =
-      (this.effectiveOwner == that.effectiveOwner) &&
+    final def isCoDefinedWith(other: Symbol)(implicit ctx: Context) =
+      (this.effectiveOwner == other.effectiveOwner) &&
       (  !(this.effectiveOwner is PackageClass)
-        || this.unforcedIsAbsent || that.unforcedIsAbsent
+        || this.unforcedIsAbsent || other.unforcedIsAbsent
         || { // check if they are defined in the same file(or a jar)
            val thisFile = this.symbol.associatedFile
-           val thatFile = that.symbol.associatedFile
+           val thatFile = other.associatedFile
            (  thisFile == null
            || thatFile == null
            || thisFile.path == thatFile.path // Cheap possibly wrong check, then expensive normalization

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

@@ -564,14 +564,20 @@ object Symbols {
      *  Overridden in ClassSymbol
      */
     def associatedFile(implicit ctx: Context): AbstractFile =
-      if (lastDenot == null) null else lastDenot.topLevelClass.symbol.associatedFile
+      if (lastDenot == null) null else lastDenot.topLevelClass.associatedFile
 
     /** The class file from which this class was generated, null if not applicable. */
     final def binaryFile(implicit ctx: Context): AbstractFile = {
       val file = associatedFile
       if (file != null && file.extension == "class") file else null
     }
 
+    /** A trap to avoid calling x.symbol on something that is already a symbol.
+     *  This would be expanded to `toDenot(x).symbol` which is guaraneteed to be
+     *  the same as `x`
+     */
+    final def symbol: Nothing = unsupported("symbol")
+
     /** The source file from which this class was generated, null if not applicable. */
     final def sourceFile(implicit ctx: Context): AbstractFile = {
       val file = associatedFile

compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala

@@ -172,7 +172,7 @@ class ClassfileParser(
       setClassInfo(classRoot, classInfo)
       setClassInfo(moduleRoot, staticInfo)
     } else if (result == Some(NoEmbedded)) {
-      for (sym <- List(moduleRoot.sourceModule.symbol, moduleRoot.symbol, classRoot.symbol)) {
+      for (sym <- List(moduleRoot.sourceModule, moduleRoot.symbol, classRoot.symbol)) {
         classRoot.owner.asClass.delete(sym)
         if (classRoot.owner == defn.ScalaShadowingPackageClass) {
           // Symbols in scalaShadowing are also added to scala

compiler/src/dotty/tools/dotc/interactive/Interactive.scala

@@ -231,8 +231,8 @@ object Interactive {
         val boundaryCtx = ctx.withOwner(boundary)
         def exclude(sym: Symbol) = sym.isAbsent || sym.is(Synthetic) || sym.is(Artifact)
         def addMember(name: Name, buf: mutable.Buffer[SingleDenotation]): Unit =
-          buf ++= prefix.member(name).altsWith(d =>
-            !exclude(d) && d.symbol.isAccessibleFrom(prefix)(boundaryCtx))
+          buf ++= prefix.member(name).altsWith(sym =>
+            !exclude(sym) && sym.isAccessibleFrom(prefix)(boundaryCtx))
           prefix.memberDenots(completionsFilter, addMember).map(_.symbol).toList
       }
       else Nil

compiler/src/dotty/tools/dotc/transform/LambdaLift.scala

@@ -190,7 +190,7 @@ object LambdaLift {
       def traverse(tree: Tree)(implicit ctx: Context) = try { //debug
         val sym = tree.symbol
 
-        def enclosure = ctx.owner.enclosingMethod.symbol
+        def enclosure = ctx.owner.enclosingMethod
 
         def narrowTo(thisClass: ClassSymbol) = {
           val enclMethod = enclosure

compiler/src/dotty/tools/dotc/transform/Mixin.scala

@@ -132,7 +132,7 @@ class Mixin extends MiniPhase with SymTransformer { thisPhase =>
             initName,
             Protected | Synthetic | Method,
             sym.info,
-            coord = sym.symbol.coord).enteredAfter(thisPhase))
+            coord = sym.coord).enteredAfter(thisPhase))
     }
   }.asTerm
 

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

@@ -279,7 +279,7 @@ object Inferencing {
       case tp: TypeRef =>
         val companion = tp.classSymbol.companionModule
         if (companion.exists)
-          companion.termRef.asSeenFrom(tp.prefix, companion.symbol.owner)
+          companion.termRef.asSeenFrom(tp.prefix, companion.owner)
         else NoType
       case _ => NoType
     }