Add companion class methods for files read from scala & java

Author: DarkDimius

src/dotty/tools/dotc/core/pickling/ClassfileParser.scala

@@ -130,10 +130,20 @@ class ClassfileParser(
     for (i <- 0 until in.nextChar) parseMember(method = true)
     classInfo = parseAttributes(classRoot.symbol, classInfo)
     if (isAnnotation) addAnnotationConstructor(classInfo)
+    if (classRoot.exists) syntecizeCompanionMethod(nme.COMPANION_CLASS_METHOD, classRoot, moduleRoot)
+
     setClassInfo(classRoot, classInfo)
     setClassInfo(moduleRoot, staticInfo)
   }
 
+  def syntecizeCompanionMethod(name: TermName, ret: SymDenotation, owner: SymDenotation)(implicit ctx: Context) = {
+    if(owner.exists) ctx.newSymbol(
+      owner = owner.symbol,
+      name = name,
+      flags = Flags.Synthetic | Flags.Private,
+      info = ExprType(ret.typeRef)).entered
+  }
+
   /** Add type parameters of enclosing classes */
   def addEnclosingTParams()(implicit ctx: Context): Unit = {
     var sym = classRoot.owner

src/dotty/tools/dotc/core/pickling/UnPickler.scala

@@ -118,6 +118,16 @@ object UnPickler {
         denot.owner.thisType select denot.sourceModule
       else selfInfo
     if (!(denot.flagsUNSAFE is JavaModule)) ensureConstructor(denot.symbol.asClass, decls)
+    if (denot.flagsUNSAFE is Module) {
+      val scalacCompanion = denot.classSymbol.scalacLinkedClass
+      if (scalacCompanion.exists)
+      ctx.newSymbol(
+        owner = denot.classSymbol,
+        name = nme.COMPANION_CLASS_METHOD,
+        flags = Flags.Synthetic | Flags.Private,
+        info = ExprType(scalacCompanion.typeRef)).entered
+    }
+
     denot.info = ClassInfo(denot.owner.thisType, denot.classSymbol, parentRefs, decls, ost)
   }
 }