Cleanup, including removing dead code.

Author: sjrd

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

@@ -110,8 +110,7 @@ class Compiler {
                                         // Note: constructors changes decls in transformTemplate, no InfoTransformers should be added after it
          new FunctionalInterfaces,   // Rewrites closures to implement @specialized types of Functions.
          new Instrumentation) ::     // Count closure allocations under -Yinstrument-closures
-    List(//new LinkScala2Impls,        // Redirect calls to trait methods defined by Scala 2.x, so that they now go to
-         new LambdaLift,             // Lifts out nested functions to class scope, storing free variables in environments
+    List(new LambdaLift,             // Lifts out nested functions to class scope, storing free variables in environments
                                      // Note: in this mini-phase block scopes are incorrect. No phases that rely on scopes should be here
          new ElimStaticThis,         // Replace `this` references to static objects by global identifiers
          new CountOuterAccesses) ::  // Identify outer accessors that can be dropped

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

@@ -380,11 +380,10 @@ object Flags {
 
   /** A module variable (Scala 2.x only)
    *    /
-   *  A Scala 2.x trait that has been partially augmented.
-   *  This is set in `AugmentScala2Trait` and reset in `LinkScala2Impls`
-   *  when the trait is fully augmented.
+   *  A Scala 2.x trait that has been augmented.
+   *  This is set in `AugmentScala2Trait` when the trait is augmented.
    */
-  val (_, Scala2ModuleVar @ _, Scala2xPartiallyAugmented @ _) = newFlags(57, "<modulevar>", "<scala-2.x-partially-augmented>")
+  val (_, Scala2ModuleVar @ _, Scala2xAugmented @ _) = newFlags(57, "<modulevar>", "<scala-2.x-augmented>")
 
   /** A macro */
   val (Macro @ _, _, _) = newFlags(58, "<macro>")

compiler/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala

@@ -38,7 +38,7 @@ class AugmentScala2Traits extends MiniPhase with IdentityDenotTransformer { this
     val cls = impl.symbol.owner.asClass
     for (mixin <- cls.mixins) {
       val erasedMixin = TypeErasure.normalizeClass(mixin)
-      if (erasedMixin.is(Scala2x) && !erasedMixin.is(Scala2xPartiallyAugmented))
+      if (erasedMixin.is(Scala2x) && !erasedMixin.is(Scala2xAugmented))
         augmentScala2Trait(erasedMixin)
     }
     impl
@@ -49,6 +49,6 @@ class AugmentScala2Traits extends MiniPhase with IdentityDenotTransformer { this
       if (sym.isSuperAccessor)
         sym.ensureNotPrivate.installAfter(thisPhase)
     }
-    mixin.setFlagFrom(thisPhase, Scala2xPartiallyAugmented)
+    mixin.setFlagFrom(thisPhase, Scala2xAugmented)
   }
 }

compiler/src/dotty/tools/dotc/transform/LinkScala2Impls.scala

@@ -160,21 +160,6 @@ class Mixin extends MiniPhase with SymTransformer { thisPhase =>
       sym
   end transformSym
 
-  private def initializer(sym: Symbol)(using Context): TermSymbol = {
-    if (sym.is(Lazy)) sym
-    else {
-      val initName = InitializerName(sym.name.asTermName)
-      sym.owner.info.decl(initName).symbol
-        .orElse(
-          newSymbol(
-            sym.owner,
-            initName,
-            Protected | Synthetic | Method,
-            sym.info,
-            coord = sym.coord).enteredAfter(thisPhase))
-    }
-  }.asTerm
-
   private def wasOneOf(sym: Symbol, flags: FlagSet)(using Context): Boolean =
     atPhase(thisPhase) { sym.isOneOf(flags) }
 

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

@@ -146,7 +146,7 @@ phases. The current list of phases is specified in class [Compiler] as follows:
          new ElimByName,             // Expand by-name parameter references
          new CollectNullableFields,  // Collect fields that can be nulled out after use in lazy initialization
          new ElimOuterSelect,        // Expand outer selections
-         new AugmentScala2Traits,    // Augments Scala2 traits with additional members needed for mixin composition.
+         new AugmentScala2Traits,    // Augments Scala2 traits so that super accessors are made non-private
          new ResolveSuper,           // Implement super accessors
          new FunctionXXLForwarders,  // Add forwarders for FunctionXXL apply method
          new TupleOptimizations,     // Optimize generic operations on tuples
@@ -168,8 +168,7 @@ phases. The current list of phases is specified in class [Compiler] as follows:
          new Instrumentation,        // Count closure allocations under -Yinstrument-closures
          new GetClass,               // Rewrites getClass calls on primitive types.
          new LiftTry) ::             // Put try expressions that might execute on non-empty stacks into their own methods their implementations
-    List(new LinkScala2Impls,        // Redirect calls to trait methods defined by Scala 2.x, so that they now go to
-         new LambdaLift,             // Lifts out nested functions to class scope, storing free variables in environments
+    List(new LambdaLift,             // Lifts out nested functions to class scope, storing free variables in environments
                                         // Note: in this mini-phase block scopes are incorrect. No phases that rely on scopes should be here
          new ElimStaticThis) ::      // Replace `this` references to static objects by global identifiers
     List(new Flatten,                // Lift all inner classes to package scope