content: /*
   * Copyright (c) 1999, 2021, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package openjdk.tools.javac.comp;
  
  import java.util.*;
  import java.util.stream.Collectors;
  
  import openjdk.tools.javac.code.*;
  import openjdk.tools.javac.code.Kinds.KindSelector;
  import openjdk.tools.javac.code.Scope.WriteableScope;
  import openjdk.tools.javac.jvm.*;
  import openjdk.tools.javac.jvm.PoolConstant.LoadableConstant;
  import openjdk.tools.javac.main.Option.PkgInfo;
  import openjdk.tools.javac.resources.CompilerProperties.Fragments;
  import openjdk.tools.javac.tree.*;
  import openjdk.tools.javac.util.*;
  import openjdk.tools.javac.util.JCDiagnostic.DiagnosticPosition;
  import openjdk.tools.javac.util.List;
  
  import openjdk.tools.javac.code.Symbol.*;
  import openjdk.tools.javac.code.Symbol.OperatorSymbol.AccessCode;
  import openjdk.tools.javac.resources.CompilerProperties.Errors;
  import openjdk.tools.javac.tree.JCTree.*;
  import openjdk.tools.javac.code.Type.*;
  
  import openjdk.tools.javac.jvm.Target;
  import openjdk.tools.javac.tree.EndPosTable;
  
  import static openjdk.tools.javac.code.Flags.*;
  import static openjdk.tools.javac.code.Flags.BLOCK;
  import static openjdk.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
  import static openjdk.tools.javac.code.TypeTag.*;
  import static openjdk.tools.javac.code.Kinds.Kind.*;
  import static openjdk.tools.javac.jvm.ByteCodes.*;
  import openjdk.tools.javac.tree.JCTree.JCBreak;
  import openjdk.tools.javac.tree.JCTree.JCCase;
  import openjdk.tools.javac.tree.JCTree.JCExpression;
  import openjdk.tools.javac.tree.JCTree.JCExpressionStatement;
  import static openjdk.tools.javac.tree.JCTree.JCOperatorExpression.OperandPos.LEFT;
  import openjdk.tools.javac.tree.JCTree.JCSwitchExpression;
  import static openjdk.tools.javac.tree.JCTree.Tag.*;
  
  /** This pass translates away some syntactic sugar: inner classes,
   *  class literals, assertions, foreach loops, etc.
   *
   *  <p><b>This is NOT part of any supported API.
   *  If you write code that depends on this, you do so at your own risk.
   *  This code and its internal interfaces are subject to change or
   *  deletion without notice.</b>
   */
  public class Lower extends TreeTranslator {
      protected static final Context.Key<Lower> lowerKey = new Context.Key<>();
  
      public static Lower instance(Context context) {
          Lower instance = context.get(lowerKey);
          if (instance == null)
              instance = new Lower(context);
          return instance;
      }
  
      private final Names names;
      private final Log log;
      private final Symtab syms;
      private final Resolve rs;
      private final Operators operators;
      private final Check chk;
      private final Attr attr;
      private TreeMaker make;
      private DiagnosticPosition make_pos;
      private final ConstFold cfolder;
      private final Target target;
      private final TypeEnvs typeEnvs;
      private final Name dollarAssertionsDisabled;
      private final Types types;
      private final Repair repair;
      private final boolean debugLower;
      private final boolean disableProtectedAccessors; // experimental
      private final PkgInfo pkginfoOpt;
  
      protected Lower(Context context) {
          context.put(lowerKey, this);
          names = Names.instance(context);
          log = Log.instance(context);
          syms = Symtab.instance(context);
          rs = Resolve.instance(context);
          operators = Operators.instance(context);
          chk = Check.instance(context);
          attr = Attr.instance(context);
          make = TreeMaker.instance(context);
          cfolder = ConstFold.instance(context);
          target = Target.instance(context);
          typeEnvs = TypeEnvs.instance(context);
          dollarAssertionsDisabled = names.
              fromString(target.syntheticNameChar() + "assertionsDisabled");
  
          types = Types.instance(context);
          repair = Repair.instance(context);
          Options options = Options.instance(context);
          debugLower = options.isSet("debuglower");
          pkginfoOpt = PkgInfo.get(options);
          disableProtectedAccessors = options.isSet("disableProtectedAccessors");
      }
  
      /** The currently enclosing class.
       */
      ClassSymbol currentClass;
  
      /** A queue of all translated classes.
       */
      ListBuffer<JCTree> translated;
  
      /** Environment for symbol lookup, set by translateTopLevelClass.
       */
      Env<AttrContext> attrEnv;
  
      /** A hash table mapping syntax trees to their ending source positions.
       */
      EndPosTable endPosTable;
  
  /**************************************************************************
   * Global mappings
   *************************************************************************/
  
      /** A hash table mapping local classes to their definitions.
       */
      Map<ClassSymbol, JCClassDecl> classdefs;
  
      /** A hash table mapping local classes to a list of pruned trees.
       */
      public Map<ClassSymbol, List<JCTree>> prunedTree = new WeakHashMap<>();
  
      /** A hash table mapping virtual accessed symbols in outer subclasses
       *  to the actually referred symbol in superclasses.
       */
      Map<Symbol,Symbol> actualSymbols;
  
      /** The current method definition.
       */
      JCMethodDecl currentMethodDef;
  
      /** The current method symbol.
       */
      MethodSymbol currentMethodSym;
  
      /** The currently enclosing outermost class definition.
       */
      JCClassDecl outermostClassDef;
  
      /** The currently enclosing outermost member definition.
       */
      JCTree outermostMemberDef;
  
      /** A map from local variable symbols to their translation (as per LambdaToMethod).
       * This is required when a capturing local class is created from a lambda (in which
       * case the captured symbols should be replaced with the translated lambda symbols).
       */
      Map<Symbol, Symbol> lambdaTranslationMap = null;
  
      /** A navigator class for assembling a mapping from local class symbols
       *  to class definition trees.
       *  There is only one case; all other cases simply traverse down the tree.
       */
      class ClassMap extends TreeScanner {
  
          /** All encountered class defs are entered into classdefs table.
           */
          public void visitClassDef(JCClassDecl tree) {
              classdefs.put(tree.sym, tree);
              super.visitClassDef(tree);
          }
      }
      ClassMap classMap = new ClassMap();
  
      /** Map a class symbol to its definition.
       *  @param c    The class symbol of which we want to determine the definition.
       */
      JCClassDecl classDef(ClassSymbol c) {
          // First lookup the class in the classdefs table.
          JCClassDecl def = classdefs.get(c);
          if (def == null && outermostMemberDef != null) {
              // If this fails, traverse outermost member definition, entering all
              // local classes into classdefs, and try again.
              classMap.scan(outermostMemberDef);
              def = classdefs.get(c);
          }
          if (def == null) {
              // If this fails, traverse outermost class definition, entering all
              // local classes into classdefs, and try again.
              classMap.scan(outermostClassDef);
              def = classdefs.get(c);
          }
          return def;
      }
  
      /** A hash table mapping class symbols to lists of free variables.
       *  accessed by them. Only free variables of the method immediately containing
       *  a class are associated with that class.
       */
      Map<ClassSymbol,List<VarSymbol>> freevarCache;
  
      /** A navigator class for collecting the free variables accessed
       *  from a local class. There is only one case; all other cases simply
       *  traverse down the tree. This class doesn't deal with the specific
       *  of Lower - it's an abstract visitor that is meant to be reused in
       *  order to share the local variable capture logic.
       */
      abstract class BasicFreeVarCollector extends TreeScanner {
  
          /** Add all free variables of class c to fvs list
           *  unless they are already there.
           */
          abstract void addFreeVars(ClassSymbol c);
  
          /** If tree refers to a variable in owner of local class, add it to
           *  free variables list.
           */
          public void visitIdent(JCIdent tree) {
              visitSymbol(tree.sym);
          }
          // where
          abstract void visitSymbol(Symbol _sym);
  
          /** If tree refers to a class instance creation expression
           *  add all free variables of the freshly created class.
           */
          public void visitNewClass(JCNewClass tree) {
              ClassSymbol c = (ClassSymbol)tree.constructor.owner;
              addFreeVars(c);
              super.visitNewClass(tree);
          }
  
          /** If tree refers to a superclass constructor call,
           *  add all free variables of the superclass.
           */
          public void visitApply(JCMethodInvocation tree) {
              if (TreeInfo.name(tree.meth) == names._super) {
                  addFreeVars((ClassSymbol) TreeInfo.symbol(tree.meth).owner);
              }
              super.visitApply(tree);
          }
  
          @Override
          public void visitYield(JCYield tree) {
              scan(tree.value);
          }
  
      }
  
      /**
       * Lower-specific subclass of {@code BasicFreeVarCollector}.
       */
      class FreeVarCollector extends BasicFreeVarCollector {
  
          /** The owner of the local class.
           */
          Symbol owner;
  
          /** The local class.
           */
          ClassSymbol clazz;
  
          /** The list of owner's variables accessed from within the local class,
           *  without any duplicates.
           */
          List<VarSymbol> fvs;
  
          FreeVarCollector(ClassSymbol clazz) {
              this.clazz = clazz;
              this.owner = clazz.owner;
              this.fvs = List.nil();
          }
  
          /** Add free variable to fvs list unless it is already there.
           */
          private void addFreeVar(VarSymbol v) {
              for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail)
                  if (l.head == v) return;
              fvs = fvs.prepend(v);
          }
  
          @Override
          void addFreeVars(ClassSymbol c) {
              List<VarSymbol> fvs = freevarCache.get(c);
              if (fvs != null) {
                  for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail) {
                      addFreeVar(l.head);
                  }
              }
          }
  
          @Override
          void visitSymbol(Symbol _sym) {
              Symbol sym = _sym;
              if (sym.kind == VAR || sym.kind == MTH) {
                  if (sym != null && sym.owner != owner)
                      sym = proxies.get(sym);
                  if (sym != null && sym.owner == owner) {
                      VarSymbol v = (VarSymbol)sym;
                      if (v.getConstValue() == null) {
                          addFreeVar(v);
                      }
                  } else {
                      if (outerThisStack.head != null &&
                          outerThisStack.head != _sym)
                          visitSymbol(outerThisStack.head);
                  }
              }
          }
  
          /** If tree refers to a class instance creation expression
           *  add all free variables of the freshly created class.
           */
          public void visitNewClass(JCNewClass tree) {
              ClassSymbol c = (ClassSymbol)tree.constructor.owner;
              if (tree.encl == null &&
                  c.hasOuterInstance() &&
                  outerThisStack.head != null)
                  visitSymbol(outerThisStack.head);
              super.visitNewClass(tree);
          }
  
          /** If tree refers to a qualified this or super expression
           *  for anything but the current class, add the outer this
           *  stack as a free variable.
           */
          public void visitSelect(JCFieldAccess tree) {
              if ((tree.name == names._this || tree.name == names._super) &&
                  tree.selected.type.tsym != clazz &&
                  outerThisStack.head != null)
                  visitSymbol(outerThisStack.head);
              super.visitSelect(tree);
          }
  
          /** If tree refers to a superclass constructor call,
           *  add all free variables of the superclass.
           */
          public void visitApply(JCMethodInvocation tree) {
              if (TreeInfo.name(tree.meth) == names._super) {
                  Symbol constructor = TreeInfo.symbol(tree.meth);
                  if (constructor.owner.kind == TYP) {
                      ClassSymbol c = (ClassSymbol)constructor.owner;
                      if (c.hasOuterInstance() &&
                          !tree.meth.hasTag(SELECT) &&
                          outerThisStack.head != null)
                          visitSymbol(outerThisStack.head);
                  }
              }
              super.visitApply(tree);
          }
  
      }
  
      ClassSymbol ownerToCopyFreeVarsFrom(ClassSymbol c) {
          if (!c.isDirectlyOrIndirectlyLocal()) {
              return null;
          }
          Symbol currentOwner = c.owner;
          while (currentOwner.owner.kind.matches(KindSelector.TYP) && currentOwner.isDirectlyOrIndirectlyLocal()) {
              currentOwner = currentOwner.owner;
          }
          if (currentOwner.owner.kind.matches(KindSelector.VAL_MTH) && c.isSubClass(currentOwner, types)) {
              return (ClassSymbol)currentOwner;
          }
          return null;
      }
  
      /** Return the variables accessed from within a local class, which
       *  are declared in the local class' owner.
       *  (in reverse order of first access).
       */
      List<VarSymbol> freevars(ClassSymbol c)  {
          List<VarSymbol> fvs = freevarCache.get(c);
          if (fvs != null) {
              return fvs;
          }
          if (c.owner.kind.matches(KindSelector.VAL_MTH)) {
              FreeVarCollector collector = new FreeVarCollector(c);
              collector.scan(classDef(c));
              fvs = collector.fvs;
              freevarCache.put(c, fvs);
              return fvs;
          } else {
              ClassSymbol owner = ownerToCopyFreeVarsFrom(c);
              if (owner != null) {
                  fvs = freevarCache.get(owner);
                  freevarCache.put(c, fvs);
                  return fvs;
              } else {
                  return List.nil();
              }
          }
      }
  
      Map<TypeSymbol,EnumMapping> enumSwitchMap = new LinkedHashMap<>();
  
      EnumMapping mapForEnum(DiagnosticPosition pos, TypeSymbol enumClass) {
          EnumMapping map = enumSwitchMap.get(enumClass);
          if (map == null)
              enumSwitchMap.put(enumClass, map = new EnumMapping(pos, enumClass));
          return map;
      }
  
      /** This map gives a translation table to be used for enum
       *  switches.
       *
       *  <p>For each enum that appears as the type of a switch
       *  expression, we maintain an EnumMapping to assist in the
       *  translation, as exemplified by the following example:
       *
       *  <p>we translate
       *  <pre>
       *          switch(colorExpression) {
       *          case red: stmt1;
       *          case green: stmt2;
       *          }
       *  </pre>
       *  into
       *  <pre>
       *          switch(Outer$0.$EnumMap$Color[colorExpression.ordinal()]) {
       *          case 1: stmt1;
       *          case 2: stmt2
       *          }
       *  </pre>
       *  with the auxiliary table initialized as follows:
       *  <pre>
       *          class Outer$0 {
       *              synthetic final int[] $EnumMap$Color = new int[Color.values().length];
       *              static {
       *                  try { $EnumMap$Color[red.ordinal()] = 1; } catch (NoSuchFieldError ex) {}
       *                  try { $EnumMap$Color[green.ordinal()] = 2; } catch (NoSuchFieldError ex) {}
       *              }
       *          }
       *  </pre>
       *  class EnumMapping provides mapping data and support methods for this translation.
       */
      class EnumMapping {
          EnumMapping(DiagnosticPosition pos, TypeSymbol forEnum) {
              this.forEnum = forEnum;
              this.values = new LinkedHashMap<>();
              this.pos = pos;
              Name varName = names
                  .fromString(target.syntheticNameChar() +
                              "SwitchMap" +
                              target.syntheticNameChar() +
                              names.fromUtf(ClassWriter.externalize(forEnum.type.tsym.flatName())).toString()
                              .replace('/', '.')
                              .replace('.', target.syntheticNameChar()));
              ClassSymbol outerCacheClass = outerCacheClass();
              this.mapVar = new VarSymbol(STATIC | SYNTHETIC | FINAL,
                                          varName,
                                          new ArrayType(syms.intType, syms.arrayClass),
                                          outerCacheClass);
              enterSynthetic(pos, mapVar, outerCacheClass.members());
          }
  
          DiagnosticPosition pos = null;
  
          // the next value to use
          int next = 1; // 0 (unused map elements) go to the default label
  
          // the enum for which this is a map
          final TypeSymbol forEnum;
  
          // the field containing the map
          final VarSymbol mapVar;
  
          // the mapped values
          final Map<VarSymbol,Integer> values;
  
          JCLiteral forConstant(VarSymbol v) {
              Integer result = values.get(v);
              if (result == null)
                  values.put(v, result = next++);
              return make.Literal(result);
          }
  
          // generate the field initializer for the map
          void translate() {
              make.at(pos.getStartPosition());
              JCClassDecl owner = classDef((ClassSymbol)mapVar.owner);
  
              // synthetic static final int[] $SwitchMap$Color = new int[Color.values().length];
              MethodSymbol valuesMethod = lookupMethod(pos,
                                                       names.values,
                                                       forEnum.type,
                                                       List.nil());
              JCExpression size = make // Color.values().length
                  .Select(make.App(make.QualIdent(valuesMethod)),
                          syms.lengthVar);
              JCExpression mapVarInit = make
                  .NewArray(make.Type(syms.intType), List.of(size), null)
                  .setType(new ArrayType(syms.intType, syms.arrayClass));
  
              // try { $SwitchMap$Color[red.ordinal()] = 1; } catch (java.lang.NoSuchFieldError ex) {}
              ListBuffer<JCStatement> stmts = new ListBuffer<>();
              Symbol ordinalMethod = lookupMethod(pos,
                                                  names.ordinal,
                                                  forEnum.type,
                                                  List.nil());
              List<JCCatch> catcher = List.<JCCatch>nil()
                  .prepend(make.Catch(make.VarDef(new VarSymbol(PARAMETER, names.ex,
                                                                syms.noSuchFieldErrorType,
                                                                syms.noSymbol),
                                                  null),
                                      make.Block(0, List.nil())));
              for (Map.Entry<VarSymbol,Integer> e : values.entrySet()) {
                  VarSymbol enumerator = e.getKey();
                  Integer mappedValue = e.getValue();
                  JCExpression assign = make
                      .Assign(make.Indexed(mapVar,
                                           make.App(make.Select(make.QualIdent(enumerator),
                                                                ordinalMethod))),
                              make.Literal(mappedValue))
                      .setType(syms.intType);
                  JCStatement exec = make.Exec(assign);
                  JCStatement _try = make.Try(make.Block(0, List.of(exec)), catcher, null);
                  stmts.append(_try);
              }
  
              owner.defs = owner.defs
                  .prepend(make.Block(STATIC, stmts.toList()))
                  .prepend(make.VarDef(mapVar, mapVarInit));
          }
      }
  
  
  /**************************************************************************
   * Tree building blocks
   *************************************************************************/
  
      /** Equivalent to make.at(pos.getStartPosition()) with side effect of caching
       *  pos as make_pos, for use in diagnostics.
       **/
      TreeMaker make_at(DiagnosticPosition pos) {
          make_pos = pos;
          return make.at(pos);
      }
  
      /** Make an attributed tree representing a literal. This will be an
       *  Ident node in the case of boolean literals, a Literal node in all
       *  other cases.
       *  @param type       The literal's type.
       *  @param value      The literal's value.
       */
      JCExpression makeLit(Type type, Object value) {
          return make.Literal(type.getTag(), value).setType(type.constType(value));
      }
  
      /** Make an attributed tree representing null.
       */
      JCExpression makeNull() {
          return makeLit(syms.botType, null);
      }
  
      /** Make an attributed class instance creation expression.
       *  @param ctype    The class type.
       *  @param args     The constructor arguments.
       */
      JCNewClass makeNewClass(Type ctype, List<JCExpression> args) {
          JCNewClass tree = make.NewClass(null,
              null, make.QualIdent(ctype.tsym), args, null);
          tree.constructor = rs.resolveConstructor(
              make_pos, attrEnv, ctype, TreeInfo.types(args), List.nil());
          tree.type = ctype;
          return tree;
      }
  
      /** Make an attributed unary expression.
       *  @param optag    The operators tree tag.
       *  @param arg      The operator's argument.
       */
      JCUnary makeUnary(JCTree.Tag optag, JCExpression arg) {
          JCUnary tree = make.Unary(optag, arg);
          tree.operator = operators.resolveUnary(tree, optag, arg.type);
          tree.type = tree.operator.type.getReturnType();
          return tree;
      }
  
      /** Make an attributed binary expression.
       *  @param optag    The operators tree tag.
       *  @param lhs      The operator's left argument.
       *  @param rhs      The operator's right argument.
       */
      JCBinary makeBinary(JCTree.Tag optag, JCExpression lhs, JCExpression rhs) {
          JCBinary tree = make.Binary(optag, lhs, rhs);
          tree.operator = operators.resolveBinary(tree, optag, lhs.type, rhs.type);
          tree.type = tree.operator.type.getReturnType();
          return tree;
      }
  
      /** Make an attributed assignop expression.
       *  @param optag    The operators tree tag.
       *  @param lhs      The operator's left argument.
       *  @param rhs      The operator's right argument.
       */
      JCAssignOp makeAssignop(JCTree.Tag optag, JCTree lhs, JCTree rhs) {
          JCAssignOp tree = make.Assignop(optag, lhs, rhs);
          tree.operator = operators.resolveBinary(tree, tree.getTag().noAssignOp(), lhs.type, rhs.type);
          tree.type = lhs.type;
          return tree;
      }
  
      /** Convert tree into string object, unless it has already a
       *  reference type..
       */
      JCExpression makeString(JCExpression tree) {
          if (!tree.type.isPrimitiveOrVoid()) {
              return tree;
          } else {
              Symbol valueOfSym = lookupMethod(tree.pos(),
                                               names.valueOf,
                                               syms.stringType,
                                               List.of(tree.type));
              return make.App(make.QualIdent(valueOfSym), List.of(tree));
          }
      }
  
      /** Create an empty anonymous class definition and enter and complete
       *  its symbol. Return the class definition's symbol.
       *  and create
       *  @param flags    The class symbol's flags
       *  @param owner    The class symbol's owner
       */
      JCClassDecl makeEmptyClass(long flags, ClassSymbol owner) {
          return makeEmptyClass(flags, owner, null, true);
      }
  
      JCClassDecl makeEmptyClass(long flags, ClassSymbol owner, Name flatname,
              boolean addToDefs) {
          // Create class symbol.
          ClassSymbol c = syms.defineClass(names.empty, owner);
          if (flatname != null) {
              c.flatname = flatname;
          } else {
              c.flatname = chk.localClassName(c);
          }
          c.sourcefile = owner.sourcefile;
          c.completer = Completer.NULL_COMPLETER;
          c.members_field = WriteableScope.create(c);
          c.flags_field = flags;
          ClassType ctype = (ClassType) c.type;
          ctype.supertype_field = syms.objectType;
          ctype.interfaces_field = List.nil();
  
          JCClassDecl odef = classDef(owner);
  
          // Enter class symbol in owner scope and compiled table.
          if (odef != null)
              enterSynthetic(odef.pos(), c, owner.members());
          chk.putCompiled(c);
  
          // Create class definition tree.
          JCClassDecl cdef = make.ClassDef(
              make.Modifiers(flags), names.empty,
              List.nil(),
              null, List.nil(), List.nil());
          cdef.sym = c;
          cdef.type = c.type;
  
          // Append class definition tree to owner's definitions.
          if (addToDefs && odef != null)
              odef.defs = odef.defs.prepend(cdef);
          return cdef;
      }
  
  /**************************************************************************
   * Symbol manipulation utilities
   *************************************************************************/
  
      /** Enter a synthetic symbol in a given scope, but complain if there was already one there.
       *  @param pos           Position for error reporting.
       *  @param sym           The symbol.
       *  @param s             The scope.
       */
      private void enterSynthetic(DiagnosticPosition pos, Symbol sym, WriteableScope s) {
          s.enter(sym);
      }
  
      /** Create a fresh synthetic name within a given scope - the unique name is
       *  obtained by appending '$' chars at the end of the name until no match
       *  is found.
       *
       * @param name base name
       * @param s scope in which the name has to be unique
       * @return fresh synthetic name
       */
      private Name makeSyntheticName(Name name, Scope s) {
          do {
              name = name.append(
                      target.syntheticNameChar(),
                      names.empty);
          } while (lookupSynthetic(name, s) != null);
          return name;
      }
  
      /** Check whether synthetic symbols generated during lowering conflict
       *  with user-defined symbols.
       *
       *  @param translatedTrees lowered class trees
       */
      void checkConflicts(List<JCTree> translatedTrees) {
          for (JCTree t : translatedTrees) {
              t.accept(conflictsChecker);
          }
      }
  
      JCTree.Visitor conflictsChecker = new TreeScanner() {
  
          TypeSymbol currentClass;
  
          @Override
          public void visitMethodDef(JCMethodDecl that) {
              checkConflicts(that.pos(), that.sym, currentClass);
              super.visitMethodDef(that);
          }
  
          @Override
          public void visitVarDef(JCVariableDecl that) {
              if (that.sym.owner.kind == TYP) {
                  checkConflicts(that.pos(), that.sym, currentClass);
              }
              super.visitVarDef(that);
          }
  
          @Override
          public void visitClassDef(JCClassDecl that) {
              TypeSymbol prevCurrentClass = currentClass;
              currentClass = that.sym;
              try {
                  super.visitClassDef(that);
              }
              finally {
                  currentClass = prevCurrentClass;
              }
          }
  
          void checkConflicts(DiagnosticPosition pos, Symbol sym, TypeSymbol c) {
              for (Type ct = c.type; ct != Type.noType ; ct = types.supertype(ct)) {
                  for (Symbol sym2 : ct.tsym.members().getSymbolsByName(sym.name, NON_RECURSIVE)) {
                      // VM allows methods and variables with differing types
                      if (sym.kind == sym2.kind &&
                          types.isSameType(types.erasure(sym.type), types.erasure(sym2.type)) &&
                          sym != sym2 &&
                          (sym.flags() & Flags.SYNTHETIC) != (sym2.flags() & Flags.SYNTHETIC) &&
                          (sym.flags() & BRIDGE) == 0 && (sym2.flags() & BRIDGE) == 0) {
                          syntheticError(pos, (sym2.flags() & SYNTHETIC) == 0 ? sym2 : sym);
                          return;
                      }
                  }
              }
          }
  
          /** Report a conflict between a user symbol and a synthetic symbol.
           */
          private void syntheticError(DiagnosticPosition pos, Symbol sym) {
              if (!sym.type.isErroneous()) {
                  log.error(pos, Errors.CannotGenerateClass(sym.location(), Fragments.SyntheticNameConflict(sym, sym.location())));
              }
          }
      };
  
      /** Look up a synthetic name in a given scope.
       *  @param s            The scope.
       *  @param name         The name.
       */
      private Symbol lookupSynthetic(Name name, Scope s) {
          Symbol sym = s.findFirst(name);
          return (sym==null || (sym.flags()&SYNTHETIC)==0) ? null : sym;
      }
  
      /** Look up a method in a given scope.
       */
      private MethodSymbol lookupMethod(DiagnosticPosition pos, Name name, Type qual, List<Type> args) {
          return rs.resolveInternalMethod(pos, attrEnv, qual, name, args, List.nil());
      }
  
      /** Anon inner classes are used as access constructor tags.
       * accessConstructorTag will use an existing anon class if one is available,
       * and synthesize a class (with makeEmptyClass) if one is not available.
       * However, there is a small possibility that an existing class will not
       * be generated as expected if it is inside a conditional with a constant
       * expression. If that is found to be the case, create an empty class tree here.
       */
      private void checkAccessConstructorTags() {
          for (List<ClassSymbol> l = accessConstrTags; l.nonEmpty(); l = l.tail) {
              ClassSymbol c = l.head;
              if (isTranslatedClassAvailable(c))
                  continue;
              JCClassDecl cdef = classdefs.get(c);
  
              Assert.checkNonNull(cdef);
  
              translate(cdef);
          }
      }
      // where
      private boolean isTranslatedClassAvailable(ClassSymbol c) {
          for (JCTree tree: translated) {
              if (tree.hasTag(CLASSDEF)
                      && ((JCClassDecl) tree).sym == c) {
                  return true;
              }
          }
          return false;
      }
  
  /**************************************************************************
   * Access methods
   *************************************************************************/
  
      /** A mapping from symbols to their access numbers.
       */
      private Map<Symbol,Integer> accessNums;
  
      /** A mapping from symbols to an array of access symbols, indexed by
       *  access code.
       */
      private Map<Symbol,MethodSymbol[]> accessSyms;
  
      /** A mapping from (constructor) symbols to access constructor symbols.
       */
      private Map<Symbol,MethodSymbol> accessConstrs;
  
      /** A list of all class symbols used for access constructor tags.
       */
      private List<ClassSymbol> accessConstrTags;
  
      /** A queue for all accessed symbols.
       */
      private ListBuffer<Symbol> accessed;
  
      /** return access code for identifier,
       *  @param tree     The tree representing the identifier use.
       *  @param enclOp   The closest enclosing operation node of tree,
       *                  null if tree is not a subtree of an operation.
       */
      private static int accessCode(JCTree tree, JCTree enclOp) {
          if (enclOp == null)
              return AccessCode.DEREF.code;
          else if (enclOp.hasTag(ASSIGN) &&
                   tree == TreeInfo.skipParens(((JCAssign) enclOp).lhs))
              return AccessCode.ASSIGN.code;
          else if ((enclOp.getTag().isIncOrDecUnaryOp() || enclOp.getTag().isAssignop()) &&
                  tree == TreeInfo.skipParens(((JCOperatorExpression) enclOp).getOperand(LEFT)))
              return (((JCOperatorExpression) enclOp).operator).getAccessCode(enclOp.getTag());
          else
              return AccessCode.DEREF.code;
      }
  
      /** Return binary operator that corresponds to given access code.
       */
      private OperatorSymbol binaryAccessOperator(int acode, Tag tag) {
          return operators.lookupBinaryOp(op -> op.getAccessCode(tag) == acode);
      }
  
      /** Return tree tag for assignment operation corresponding
       *  to given binary operator.
       */
      private static JCTree.Tag treeTag(OperatorSymbol operator) {
          switch (operator.opcode) {
          case ByteCodes.ior: case ByteCodes.lor:
              return BITOR_ASG;
          case ByteCodes.ixor: case ByteCodes.lxor:
              return BITXOR_ASG;
          case ByteCodes.iand: case ByteCodes.land:
              return BITAND_ASG;
          case ByteCodes.ishl: case ByteCodes.lshl:
          case ByteCodes.ishll: case ByteCodes.lshll:
              return SL_ASG;
          case ByteCodes.ishr: case ByteCodes.lshr:
          case ByteCodes.ishrl: case ByteCodes.lshrl:
              return SR_ASG;
          case ByteCodes.iushr: case ByteCodes.lushr:
          case ByteCodes.iushrl: case ByteCodes.lushrl:
              return USR_ASG;
          case ByteCodes.iadd: case ByteCodes.ladd:
          case ByteCodes.fadd: case ByteCodes.dadd:
          case ByteCodes.string_add:
              return PLUS_ASG;
          case ByteCodes.isub: case ByteCodes.lsub:
          case ByteCodes.fsub: case ByteCodes.dsub:
              return MINUS_ASG;
          case ByteCodes.imul: case ByteCodes.lmul:
          case ByteCodes.fmul: case ByteCodes.dmul:
              return MUL_ASG;
          case ByteCodes.idiv: case ByteCodes.ldiv:
          case ByteCodes.fdiv: case ByteCodes.ddiv:
              return DIV_ASG;
          case ByteCodes.imod: case ByteCodes.lmod:
          case ByteCodes.fmod: case ByteCodes.dmod:
              return MOD_ASG;
          default:
              throw new AssertionError();
          }
      }
  
      /** The name of the access method with number `anum' and access code `acode'.
       */
      Name accessName(int anum, int acode) {
          return names.fromString(
              "access" + target.syntheticNameChar() + anum + acode / 10 + acode % 10);
      }
  
      /** Return access symbol for a private or protected symbol from an inner class.
       *  @param sym        The accessed private symbol.
       *  @param tree       The accessing tree.
       *  @param enclOp     The closest enclosing operation node of tree,
       *                    null if tree is not a subtree of an operation.
       *  @param protAccess Is access to a protected symbol in another
       *                    package?
       *  @param refSuper   Is access via a (qualified) C.super?
       */
      MethodSymbol accessSymbol(Symbol sym, JCTree tree, JCTree enclOp,
                                boolean protAccess, boolean refSuper) {
          ClassSymbol accOwner = refSuper && protAccess
              // For access via qualified super (T.super.x), place the
              // access symbol on T.
              ? (ClassSymbol)((JCFieldAccess) tree).selected.type.tsym
              // Otherwise pretend that the owner of an accessed
              // protected symbol is the enclosing class of the current
              // class which is a subclass of the symbol's owner.
              : accessClass(sym, protAccess, tree);
  
          Symbol vsym = sym;
          if (sym.owner != accOwner) {
              vsym = sym.clone(accOwner);
              actualSymbols.put(vsym, sym);
          }
  
          Integer anum              // The access number of the access method.
              = accessNums.get(vsym);
          if (anum == null) {
              anum = accessed.length();
              accessNums.put(vsym, anum);
              accessSyms.put(vsym, new MethodSymbol[AccessCode.numberOfAccessCodes]);
              accessed.append(vsym);
              // System.out.println("accessing " + vsym + " in " + vsym.location());
          }
  
          int acode;                // The access code of the access method.
          List<Type> argtypes;      // The argument types of the access method.
          Type restype;             // The result type of the access method.
          List<Type> thrown;        // The thrown exceptions of the access method.
          switch (vsym.kind) {
          case VAR:
              acode = accessCode(tree, enclOp);
              if (acode >= AccessCode.FIRSTASGOP.code) {
                  OperatorSymbol operator = binaryAccessOperator(acode, enclOp.getTag());
                  if (operator.opcode == string_add)
                      argtypes = List.of(syms.objectType);
                  else
                      argtypes = operator.type.getParameterTypes().tail;
              } else if (acode == AccessCode.ASSIGN.code)
                  argtypes = List.of(vsym.erasure(types));
              else
                  argtypes = List.nil();
              restype = vsym.erasure(types);
              thrown = List.nil();
              break;
          case MTH:
              acode = AccessCode.DEREF.code;
              argtypes = vsym.erasure(types).getParameterTypes();
              restype = vsym.erasure(types).getReturnType();
              thrown = vsym.type.getThrownTypes();
              break;
          default:
              throw new AssertionError();
          }
  
          // For references via qualified super, increment acode by one,
          // making it odd.
          if (protAccess && refSuper) acode++;
  
          // Instance access methods get instance as first parameter.
          // For protected symbols this needs to be the instance as a member
          // of the type containing the accessed symbol, not the class
          // containing the access method.
          if ((vsym.flags() & STATIC) == 0) {
              argtypes = argtypes.prepend(vsym.owner.erasure(types));
          }
          MethodSymbol[] accessors = accessSyms.get(vsym);
          MethodSymbol accessor = accessors[acode];
          if (accessor == null) {
              accessor = new MethodSymbol(
                  STATIC | SYNTHETIC | (accOwner.isInterface() ? PUBLIC : 0),
                  accessName(anum.intValue(), acode),
                  new MethodType(argtypes, restype, thrown, syms.methodClass),
                  accOwner);
              enterSynthetic(tree.pos(), accessor, accOwner.members());
              accessors[acode] = accessor;
          }
          return accessor;
      }
  
      /** The qualifier to be used for accessing a symbol in an outer class.
       *  This is either C.sym or C.this.sym, depending on whether or not
       *  sym is static.
       *  @param sym   The accessed symbol.
       */
      JCExpression accessBase(DiagnosticPosition pos, Symbol sym) {
          return (sym.flags() & STATIC) != 0
              ? access(make.at(pos.getStartPosition()).QualIdent(sym.owner))
              : makeOwnerThis(pos, sym, true);
      }
  
      /** Do we need an access method to reference private symbol?
       */
      boolean needsPrivateAccess(Symbol sym) {
          if (target.hasNestmateAccess()) {
              return false;
          }
          if ((sym.flags() & PRIVATE) == 0 || sym.owner == currentClass) {
              return false;
          } else if (sym.name == names.init && sym.owner.isDirectlyOrIndirectlyLocal()) {
              // private constructor in local class: relax protection
              sym.flags_field &= ~PRIVATE;
              return false;
          } else {
              return true;
          }
      }
  
      /** Do we need an access method to reference symbol in other package?
       */
      boolean needsProtectedAccess(Symbol sym, JCTree tree) {
          if (disableProtectedAccessors) return false;
          if ((sym.flags() & PROTECTED) == 0 ||
              sym.owner.owner == currentClass.owner || // fast special case
              sym.packge() == currentClass.packge())
              return false;
          if (!currentClass.isSubClass(sym.owner, types))
              return true;
          if ((sym.flags() & STATIC) != 0 ||
              !tree.hasTag(SELECT) ||
              TreeInfo.name(((JCFieldAccess) tree).selected) == names._super)
              return false;
          return !((JCFieldAccess) tree).selected.type.tsym.isSubClass(currentClass, types);
      }
  
      /** The class in which an access method for given symbol goes.
       *  @param sym        The access symbol
       *  @param protAccess Is access to a protected symbol in another
       *                    package?
       */
      ClassSymbol accessClass(Symbol sym, boolean protAccess, JCTree tree) {
          if (protAccess) {
              Symbol qualifier = null;
              ClassSymbol c = currentClass;
              if (tree.hasTag(SELECT) && (sym.flags() & STATIC) == 0) {
                  qualifier = ((JCFieldAccess) tree).selected.type.tsym;
                  while (!qualifier.isSubClass(c, types)) {
                      c = c.owner.enclClass();
                  }
                  return c;
              } else {
                  while (!c.isSubClass(sym.owner, types)) {
                      c = c.owner.enclClass();
                  }
              }
              return c;
          } else {
              // the symbol is private
              return sym.owner.enclClass();
          }
      }
  
      private void addPrunedInfo(JCTree tree) {
          List<JCTree> infoList = prunedTree.get(currentClass);
          infoList = (infoList == null) ? List.of(tree) : infoList.prepend(tree);
          prunedTree.put(currentClass, infoList);
      }
  
      /** Ensure that identifier is accessible, return tree accessing the identifier.
       *  @param sym      The accessed symbol.
       *  @param tree     The tree referring to the symbol.
       *  @param enclOp   The closest enclosing operation node of tree,
       *                  null if tree is not a subtree of an operation.
       *  @param refSuper Is access via a (qualified) C.super?
       */
      JCExpression access(Symbol sym, JCExpression tree, JCExpression enclOp, boolean refSuper) {
          // Access a free variable via its proxy, or its proxy's proxy
          while (sym.kind == VAR && sym.owner.kind == MTH &&
              sym.owner.enclClass() != currentClass) {
              // A constant is replaced by its constant value.
              Object cv = ((VarSymbol)sym).getConstValue();
              if (cv != null) {
                  make.at(tree.pos);
                  return makeLit(sym.type, cv);
              }
              if (lambdaTranslationMap != null && lambdaTranslationMap.get(sym) != null) {
                  return make.at(tree.pos).Ident(lambdaTranslationMap.get(sym));
              } else {
                  // Otherwise replace the variable by its proxy.
                  sym = proxies.get(sym);
                  if (sym != null && (sym.flags_field & FINAL) != 0) {
                      tree = make.at(tree.pos).Ident(sym);
                  } else {
                      make.at(tree.pos);
                      return repair.generateErrExpr(make, tree, "Cannot find proxy for the variable");
                  }
              }
          }
          JCExpression base = (tree.hasTag(SELECT)) ? ((JCFieldAccess) tree).selected : null;
          switch (sym.kind) {
          case TYP:
              if (sym.owner.kind != PCK) {
                  // Convert type idents to
                  // <flat name> or <package name> . <flat name>
                  Name flatname = Convert.shortName(sym.flatName());
                  while (base != null &&
                         TreeInfo.symbol(base) != null &&
                         TreeInfo.symbol(base).kind != PCK) {
                      base = (base.hasTag(SELECT))
                          ? ((JCFieldAccess) base).selected
                          : null;
                  }
                  if (tree.hasTag(IDENT)) {
                      ((JCIdent) tree).name = flatname;
                  } else if (base == null) {
                      tree = make.at(tree.pos).Ident(sym);
                      ((JCIdent) tree).name = flatname;
                  } else {
                      ((JCFieldAccess) tree).selected = base;
                      ((JCFieldAccess) tree).name = flatname;
                  }
              }
              break;
          case MTH: case VAR:
              if (sym.owner.kind == TYP) {
  
                  // Access methods are required for
                  //  - private members,
                  //  - protected members in a superclass of an
                  //    enclosing class contained in another package.
                  //  - all non-private members accessed via a qualified super.
                  boolean protAccess = refSuper && !needsPrivateAccess(sym)
                      || needsProtectedAccess(sym, tree);
                  boolean accReq = protAccess || needsPrivateAccess(sym);
  
                  // A base has to be supplied for
                  //  - simple identifiers accessing variables in outer classes.
                  boolean baseReq =
                      base == null &&
                      sym.owner != syms.predefClass &&
                      !sym.isMemberOf(currentClass, types);
  
                  if (accReq || baseReq) {
                      make.at(tree.pos);
  
                      // Constants are replaced by their constant value.
                      if (sym.kind == VAR) {
                          Object cv = ((VarSymbol)sym).getConstValue();
                          if (cv != null) {
                              addPrunedInfo(tree);
                              return makeLit(sym.type, cv);
                          }
                      }
  
                      // Private variables and methods are replaced by calls
                      // to their access methods.
                      if (accReq) {
                          List<JCExpression> args = List.nil();
                          if ((sym.flags() & STATIC) == 0) {
                              // Instance access methods get instance
                              // as first parameter.
                              if (base == null)
                                  base = makeOwnerThis(tree.pos(), sym, true);
                              args = args.prepend(base);
                              base = null;   // so we don't duplicate code
                          }
                          Symbol access = accessSymbol(sym, tree,
                                                       enclOp, protAccess,
                                                       refSuper);
                          JCExpression receiver = make.Select(
                              base != null ? base : make.QualIdent(access.owner),
                              access);
                          return make.App(receiver, args);
  
                      // Other accesses to members of outer classes get a
                      // qualifier.
                      } else if (baseReq) {
                          return make.at(tree.pos).Select(
                              accessBase(tree.pos(), sym), sym).setType(tree.type);
                      }
                  }
              } else if (sym.owner.kind == MTH && lambdaTranslationMap != null) {
                  //sym is a local variable - check the lambda translation map to
                  //see if sym has been translated to something else in the current
                  //scope (by LambdaToMethod)
                  Symbol translatedSym = lambdaTranslationMap.get(sym.baseSymbol());
                  if (translatedSym != null) {
                      tree = make.at(tree.pos).Ident(translatedSym);
                  }
              }
          }
          return tree;
      }
  
      /** Ensure that identifier is accessible, return tree accessing the identifier.
       *  @param tree     The identifier tree.
       */
      JCExpression access(JCExpression tree) {
          Symbol sym = TreeInfo.symbol(tree);
          return sym == null ? tree : access(sym, tree, null, false);
      }
  
      /** Return access constructor for a private constructor,
       *  or the constructor itself, if no access constructor is needed.
       *  @param pos       The position to report diagnostics, if any.
       *  @param constr    The private constructor.
       */
      Symbol accessConstructor(DiagnosticPosition pos, Symbol constr) {
          if (needsPrivateAccess(constr)) {
              ClassSymbol accOwner = constr.owner.enclClass();
              MethodSymbol aconstr = accessConstrs.get(constr);
              if (aconstr == null) {
                  List<Type> argtypes = constr.type.getParameterTypes();
                  if ((accOwner.flags_field & ENUM) != 0)
                      argtypes = argtypes
                          .prepend(syms.intType)
                          .prepend(syms.stringType);
                  aconstr = new MethodSymbol(
                      SYNTHETIC,
                      names.init,
                      new MethodType(
                          argtypes.append(
                              accessConstructorTag().erasure(types)),
                          constr.type.getReturnType(),
                          constr.type.getThrownTypes(),
                          syms.methodClass),
                      accOwner);
                  enterSynthetic(pos, aconstr, accOwner.members());
                  accessConstrs.put(constr, aconstr);
                  accessed.append(constr);
              }
              return aconstr;
          } else {
              return constr;
          }
      }
  
      /** Return an anonymous class nested in this toplevel class.
       */
      ClassSymbol accessConstructorTag() {
          ClassSymbol topClass = currentClass.outermostClass();
          ModuleSymbol topModle = topClass.packge().modle;
          for (int i = 1; ; i++) {
              Name flatname = names.fromString("" + topClass.getQualifiedName() +
                                              target.syntheticNameChar() +
                                              i);
              ClassSymbol ctag = chk.getCompiled(topModle, flatname);
              if (ctag != null && !isTranslatedClassAvailable(ctag)) {
                  ctag = null;
              }
              if (ctag == null)
                  ctag = makeEmptyClass(STATIC | SYNTHETIC, topClass).sym;
              else if (!ctag.isAnonymous())
                  continue;
              // keep a record of all tags, to verify that all are generated as required
              accessConstrTags = accessConstrTags.prepend(ctag);
              return ctag;
          }
      }
  
      /** Add all required access methods for a private symbol to enclosing class.
       *  @param sym       The symbol.
       */
      void makeAccessible(Symbol sym) {
          JCClassDecl cdef = classDef(sym.owner.enclClass());
          if (cdef == null) Assert.error("class def not found: " + sym + " in " + sym.owner + "\nflags: " + sym.flags() +
                  "\noutermostMemberDef: " + outermostMemberDef + "\noutermostClassDef: " + outermostClassDef);
          if (sym.name == names.init) {
              cdef.defs = cdef.defs.prepend(
                  accessConstructorDef(cdef.pos, sym, accessConstrs.get(sym)));
          } else {
              MethodSymbol[] accessors = accessSyms.get(sym);
              for (int i = 0; i < AccessCode.numberOfAccessCodes; i++) {
                  if (accessors[i] != null)
                      cdef.defs = cdef.defs.prepend(
                          accessDef(cdef.pos, sym, accessors[i], i));
              }
          }
      }
  
      /** Construct definition of an access method.
       *  @param pos        The source code position of the definition.
       *  @param vsym       The private or protected symbol.
       *  @param accessor   The access method for the symbol.
       *  @param acode      The access code.
       */
      JCTree accessDef(int pos, Symbol vsym, MethodSymbol accessor, int acode) {
  //      System.err.println("access " + vsym + " with " + accessor);//DEBUG
          currentClass = vsym.owner.enclClass();
          make.at(pos);
          JCMethodDecl md = make.MethodDef(accessor, null);
  
          // Find actual symbol
          Symbol sym = actualSymbols.get(vsym);
          if (sym == null) sym = vsym;
  
          JCExpression ref;           // The tree referencing the private symbol.
          List<JCExpression> args;    // Any additional arguments to be passed along.
          if ((sym.flags() & STATIC) != 0) {
              ref = make.Ident(sym);
              args = make.Idents(md.params);
          } else {
              JCExpression site = make.Ident(md.params.head);
              if (acode % 2 != 0) {
                  //odd access codes represent qualified super accesses - need to
                  //emit reference to the direct superclass, even if the referred
                  //member is from an indirect superclass (JLS 13.1)
                  site.setType(types.erasure(types.supertype(vsym.owner.enclClass().type)));
              }
              ref = make.Select(site, sym);
              args = make.Idents(md.params.tail);
          }
          JCStatement stat;          // The statement accessing the private symbol.
          if (sym.kind == VAR) {
              // Normalize out all odd access codes by taking floor modulo 2:
              int acode1 = acode - (acode & 1);
  
              JCExpression expr;      // The access method's return value.
              AccessCode aCode = AccessCode.getFromCode(acode1);
              switch (aCode) {
              case DEREF:
                  expr = ref;
                  break;
              case ASSIGN:
                  expr = make.Assign(ref, args.head);
                  break;
              case PREINC: case POSTINC: case PREDEC: case POSTDEC:
                  expr = makeUnary(aCode.tag, ref);
                  break;
              default:
                  expr = make.Assignop(
                      treeTag(binaryAccessOperator(acode1, JCTree.Tag.NO_TAG)), ref, args.head);
                  ((JCAssignOp) expr).operator = binaryAccessOperator(acode1, JCTree.Tag.NO_TAG);
              }
              stat = make.Return(expr.setType(sym.type));
          } else {
              stat = make.Call(make.App(ref, args));
          }
          md.body = make.Block(0, List.of(stat));
  
          // Make sure all parameters, result types and thrown exceptions
          // are accessible.
          for (List<JCVariableDecl> l = md.params; l.nonEmpty(); l = l.tail)
              l.head.vartype = access(l.head.vartype);
          md.restype = access(md.restype);
          for (List<JCExpression> l = md.thrown; l.nonEmpty(); l = l.tail)
              l.head = access(l.head);
  
          return md;
      }
  
      /** Construct definition of an access constructor.
       *  @param pos        The source code position of the definition.
       *  @param constr     The private constructor.
       *  @param accessor   The access method for the constructor.
       */
      JCTree accessConstructorDef(int pos, Symbol constr, MethodSymbol accessor) {
          make.at(pos);
          JCMethodDecl md = make.MethodDef(accessor,
                                        accessor.externalType(types),
                                        null);
          JCIdent callee = make.Ident(names._this);
          callee.sym = constr;
          callee.type = constr.type;
          md.body =
              make.Block(0, List.of(
                  make.Call(
                      make.App(
                          callee,
                          make.Idents(md.params.reverse().tail.reverse())))));
          return md;
      }
  
  /**************************************************************************
   * Free variables proxies and this$n
   *************************************************************************/
  
      /** A map which allows to retrieve the translated proxy variable for any given symbol of an
       *  enclosing scope that is accessed (the accessed symbol could be the synthetic 'this$n' symbol).
       *  Inside a constructor, the map temporarily overrides entries corresponding to proxies and any
       *  'this$n' symbols, where they represent the constructor parameters.
       */
      Map<Symbol, Symbol> proxies;
  
      /** A scope containing all unnamed resource variables/saved
       *  exception variables for translated TWR blocks
       */
      WriteableScope twrVars;
  
      /** A stack containing the this$n field of the currently translated
       *  classes (if needed) in innermost first order.
       *  Inside a constructor, proxies and any this$n symbol are duplicated
       *  in an additional innermost scope, where they represent the constructor
       *  parameters.
       */
      List<VarSymbol> outerThisStack;
  
      /** The name of a free variable proxy.
       */
      Name proxyName(Name name, int index) {
          Name proxyName = names.fromString("val" + target.syntheticNameChar() + name);
          if (index > 0) {
              proxyName = proxyName.append(names.fromString("" + target.syntheticNameChar() + index));
          }
          return proxyName;
      }
  
      /** Proxy definitions for all free variables in given list, in reverse order.
       *  @param pos        The source code position of the definition.
       *  @param freevars   The free variables.
       *  @param owner      The class in which the definitions go.
       */
      List<JCVariableDecl> freevarDefs(int pos, List<VarSymbol> freevars, Symbol owner) {
          return freevarDefs(pos, freevars, owner, 0);
      }
  
      List<JCVariableDecl> freevarDefs(int pos, List<VarSymbol> freevars, Symbol owner,
              long additionalFlags) {
          long flags = FINAL | SYNTHETIC | additionalFlags;
          List<JCVariableDecl> defs = List.nil();
          Set<Name> proxyNames = new HashSet<>();
          for (List<VarSymbol> l = freevars; l.nonEmpty(); l = l.tail) {
              VarSymbol v = l.head;
              int index = 0;
              Name proxyName;
              do {
                  proxyName = proxyName(v.name, index++);
              } while (!proxyNames.add(proxyName));
              VarSymbol proxy = new VarSymbol(
                  flags, proxyName, v.erasure(types), owner);
              proxies.put(v, proxy);
              JCVariableDecl vd = make.at(pos).VarDef(proxy, null);
              vd.vartype = access(vd.vartype);
              defs = defs.prepend(vd);
          }
          return defs;
      }
  
      /** The name of a this$n field
       *  @param type   The class referenced by the this$n field
       */
      Name outerThisName(Type type, Symbol owner) {
          Type t = type.getEnclosingType();
          int nestingLevel = 0;
          while (t.hasTag(CLASS)) {
              t = t.getEnclosingType();
              nestingLevel++;
          }
          Name result = names.fromString("this" + target.syntheticNameChar() + nestingLevel);
          while (owner.kind == TYP && ((ClassSymbol)owner).members().findFirst(result) != null)
              result = names.fromString(result.toString() + target.syntheticNameChar());
          return result;
      }
  
      private VarSymbol makeOuterThisVarSymbol(Symbol owner, long flags) {
          Type target = types.erasure(owner.enclClass().type.getEnclosingType());
          VarSymbol outerThis =
              new VarSymbol(flags, outerThisName(target, owner), target, owner);
          outerThisStack = outerThisStack.prepend(outerThis);
          return outerThis;
      }
  
      private JCVariableDecl makeOuterThisVarDecl(int pos, VarSymbol sym) {
          JCVariableDecl vd = make.at(pos).VarDef(sym, null);
          vd.vartype = access(vd.vartype);
          return vd;
      }
  
      /** Definition for this$n field.
       *  @param pos        The source code position of the definition.
       *  @param owner      The method in which the definition goes.
       */
      JCVariableDecl outerThisDef(int pos, MethodSymbol owner) {
          ClassSymbol c = owner.enclClass();
          boolean isMandated =
              // Anonymous constructors
              (owner.isConstructor() && owner.isAnonymous()) ||
              // Constructors of non-private inner member classes
              (owner.isConstructor() && c.isInner() &&
               !c.isPrivate() && !c.isStatic());
          long flags =
              FINAL | (isMandated ? MANDATED : SYNTHETIC) | PARAMETER;
          VarSymbol outerThis = makeOuterThisVarSymbol(owner, flags);
          owner.extraParams = owner.extraParams.prepend(outerThis);
          return makeOuterThisVarDecl(pos, outerThis);
      }
  
      /** Definition for this$n field.
       *  @param pos        The source code position of the definition.
       *  @param owner      The class in which the definition goes.
       */
      JCVariableDecl outerThisDef(int pos, ClassSymbol owner) {
          VarSymbol outerThis = makeOuterThisVarSymbol(owner, FINAL | SYNTHETIC);
          return makeOuterThisVarDecl(pos, outerThis);
      }
  
      /** Return a list of trees that load the free variables in given list,
       *  in reverse order.
       *  @param pos          The source code position to be used for the trees.
       *  @param freevars     The list of free variables.
       */
      List<JCExpression> loadFreevars(DiagnosticPosition pos, List<VarSymbol> freevars) {
          List<JCExpression> args = List.nil();
          for (List<VarSymbol> l = freevars; l.nonEmpty(); l = l.tail)
              args = args.prepend(loadFreevar(pos, l.head));
          return args;
      }
  //where
          JCExpression loadFreevar(DiagnosticPosition pos, VarSymbol v) {
              return access(v, make.at(pos).Ident(v), null, false);
          }
  
      /** Construct a tree simulating the expression {@code C.this}.
       *  @param pos           The source code position to be used for the tree.
       *  @param c             The qualifier class.
       */
      JCExpression makeThis(DiagnosticPosition pos, TypeSymbol c) {
          if (currentClass == c) {
              // in this case, `this' works fine
              return make.at(pos).This(c.erasure(types));
          } else {
              // need to go via this$n
              return makeOuterThis(pos, c);
          }
      }
  
      /**
       * Optionally replace a try statement with the desugaring of a
       * try-with-resources statement.  The canonical desugaring of
       *
       * try ResourceSpecification
       *   Block
       *
       * is
       *
       * {
       *   final VariableModifiers_minus_final R #resource = Expression;
       *
       *   try ResourceSpecificationtail
       *     Block
       *   } body-only-finally {
       *     if (#resource != null) //nullcheck skipped if Expression is provably non-null
       *         #resource.close();
       *   } catch (Throwable #primaryException) {
       *       if (#resource != null) //nullcheck skipped if Expression is provably non-null
       *           try {
       *               #resource.close();
       *           } catch (Throwable #suppressedException) {
       *              #primaryException.addSuppressed(#suppressedException);
       *           }
       *       throw #primaryException;
       *   }
       * }
       *
       * @param tree  The try statement to inspect.
       * @return A a desugared try-with-resources tree, or the original
       * try block if there are no resources to manage.
       */
      JCTree makeTwrTry(JCTry tree) {
          make_at(tree.pos());
          twrVars = twrVars.dup();
          JCBlock twrBlock = makeTwrBlock(tree.resources, tree.body, 0);
          if (tree.catchers.isEmpty() && tree.finalizer == null)
              result = translate(twrBlock);
          else
              result = translate(make.Try(twrBlock, tree.catchers, tree.finalizer));
          twrVars = twrVars.leave();
          return result;
      }
  
      private JCBlock makeTwrBlock(List<JCTree> resources, JCBlock block, int depth) {
          if (resources.isEmpty())
              return block;
  
          // Add resource declaration or expression to block statements
          ListBuffer<JCStatement> stats = new ListBuffer<>();
          JCTree resource = resources.head;
          JCExpression resourceUse;
          boolean resourceNonNull;
          if (resource instanceof JCVariableDecl) {
              JCVariableDecl var = (JCVariableDecl) resource;
              resourceUse = make.Ident(var.sym).setType(resource.type);
              resourceNonNull = var.init != null && TreeInfo.skipParens(var.init).hasTag(NEWCLASS);
              stats.add(var);
          } else {
              Assert.check(resource instanceof JCExpression);
              VarSymbol syntheticTwrVar =
              new VarSymbol(SYNTHETIC | FINAL,
                            makeSyntheticName(names.fromString("twrVar" +
                                             depth), twrVars),
                            (resource.type.hasTag(BOT)) ?
                            syms.autoCloseableType : resource.type,
                            currentMethodSym);
              twrVars.enter(syntheticTwrVar);
              JCVariableDecl syntheticTwrVarDecl =
                  make.VarDef(syntheticTwrVar, (JCExpression)resource);
              resourceUse = (JCExpression)make.Ident(syntheticTwrVar);
              resourceNonNull = false;
              stats.add(syntheticTwrVarDecl);
          }
  
          //create (semi-) finally block that will be copied into the main try body:
          int oldPos = make.pos;
          make.at(TreeInfo.endPos(block));
  
          // if (#resource != null) { #resource.close(); }
          JCStatement bodyCloseStatement = makeResourceCloseInvocation(resourceUse);
  
          if (!resourceNonNull) {
              bodyCloseStatement = make.If(makeNonNullCheck(resourceUse),
                                           bodyCloseStatement,
                                           null);
          }
  
          JCBlock finallyClause = make.Block(BODY_ONLY_FINALIZE, List.of(bodyCloseStatement));
          make.at(oldPos);
  
          // Create catch clause that saves exception, closes the resource and then rethrows the exception:
          VarSymbol primaryException =
              new VarSymbol(FINAL|SYNTHETIC,
                            names.fromString("t" +
                                             target.syntheticNameChar()),
                            syms.throwableType,
                            currentMethodSym);
          JCVariableDecl primaryExceptionDecl = make.VarDef(primaryException, null);
  
          // close resource:
          // try {
          //     #resource.close();
          // } catch (Throwable #suppressedException) {
          //     #primaryException.addSuppressed(#suppressedException);
          // }
          VarSymbol suppressedException =
              new VarSymbol(SYNTHETIC, make.paramName(2),
                            syms.throwableType,
                            currentMethodSym);
          JCStatement addSuppressedStatement =
              make.Exec(makeCall(make.Ident(primaryException),
                                 names.addSuppressed,
                                 List.of(make.Ident(suppressedException))));
          JCBlock closeResourceTryBlock =
              make.Block(0L, List.of(makeResourceCloseInvocation(resourceUse)));
          JCVariableDecl catchSuppressedDecl = make.VarDef(suppressedException, null);
          JCBlock catchSuppressedBlock = make.Block(0L, List.of(addSuppressedStatement));
          List<JCCatch> catchSuppressedClauses =
                  List.of(make.Catch(catchSuppressedDecl, catchSuppressedBlock));
          JCTry closeResourceTry = make.Try(closeResourceTryBlock, catchSuppressedClauses, null);
          closeResourceTry.finallyCanCompleteNormally = true;
  
          JCStatement exceptionalCloseStatement = closeResourceTry;
  
          if (!resourceNonNull) {
              // if (#resource != null) {  }
              exceptionalCloseStatement = make.If(makeNonNullCheck(resourceUse),
                                                  exceptionalCloseStatement,
                                                  null);
          }
  
          JCStatement exceptionalRethrow = make.Throw(make.Ident(primaryException));
          JCBlock exceptionalCloseBlock = make.Block(0L, List.of(exceptionalCloseStatement, exceptionalRethrow));
          JCCatch exceptionalCatchClause = make.Catch(primaryExceptionDecl, exceptionalCloseBlock);
  
          //create the main try statement with the close:
          JCTry outerTry = make.Try(makeTwrBlock(resources.tail, block, depth + 1),
                                    List.of(exceptionalCatchClause),
                                    finallyClause);
  
          outerTry.finallyCanCompleteNormally = true;
          stats.add(outerTry);
  
          JCBlock newBlock = make.Block(0L, stats.toList());
          return newBlock;
      }
  
      private JCStatement makeResourceCloseInvocation(JCExpression resource) {
          // convert to AutoCloseable if needed
          if (types.asSuper(resource.type, syms.autoCloseableType.tsym) == null) {
              resource = convert(resource, syms.autoCloseableType);
          }
  
          // create resource.close() method invocation
          JCExpression resourceClose = makeCall(resource,
                                                names.close,
                                                List.nil());
          return make.Exec(resourceClose);
      }
  
      private JCExpression makeNonNullCheck(JCExpression expression) {
          return makeBinary(NE, expression, makeNull());
      }
  
      /** Construct a tree that represents the outer instance
       *  {@code C.this}. Never pick the current `this'.
       *  @param pos           The source code position to be used for the tree.
       *  @param c             The qualifier class.
       */
      JCExpression makeOuterThis(DiagnosticPosition pos, TypeSymbol c) {
          List<VarSymbol> ots = outerThisStack;
          if (ots.isEmpty()) {
              log.error(pos, Errors.NoEnclInstanceOfTypeInScope(c));
              return makeNull();
          }
          VarSymbol ot = ots.head;
          JCExpression tree = access(make.at(pos).Ident(ot));
          TypeSymbol otc = ot.type.tsym;
          while (otc != c) {
              do {
                  ots = ots.tail;
                  if (ots.isEmpty()) {
                      log.error(pos, Errors.NoEnclInstanceOfTypeInScope(c));
                      return tree;
                  }
                  ot = ots.head;
              } while (ot.owner != otc);
              if (otc.owner.kind != PCK && !otc.hasOuterInstance()) {
                  chk.earlyRefError(pos, c);
                  return makeNull();
              }
              tree = access(make.at(pos).Select(tree, ot));
              otc = ot.type.tsym;
          }
          return tree;
      }
  
      /** Construct a tree that represents the closest outer instance
       *  {@code C.this} such that the given symbol is a member of C.
       *  @param pos           The source code position to be used for the tree.
       *  @param sym           The accessed symbol.
       *  @param preciseMatch  should we accept a type that is a subtype of
       *                       sym's owner, even if it doesn't contain sym
       *                       due to hiding, overriding, or non-inheritance
       *                       due to protection?
       */
      JCExpression makeOwnerThis(DiagnosticPosition pos, Symbol sym, boolean preciseMatch) {
          Symbol c = sym.owner;
          if (preciseMatch ? sym.isMemberOf(currentClass, types)
                           : currentClass.isSubClass(sym.owner, types)) {
              // in this case, `this' works fine
              return make.at(pos).This(c.erasure(types));
          } else {
              // need to go via this$n
              return makeOwnerThisN(pos, sym, preciseMatch);
          }
      }
  
      /**
       * Similar to makeOwnerThis but will never pick "this".
       */
      JCExpression makeOwnerThisN(DiagnosticPosition pos, Symbol sym, boolean preciseMatch) {
          Symbol c = sym.owner;
          List<VarSymbol> ots = outerThisStack;
          if (ots.isEmpty()) {
              log.error(pos, Errors.NoEnclInstanceOfTypeInScope(c));
              return makeNull();
          }
          VarSymbol ot = ots.head;
          JCExpression tree = access(make.at(pos).Ident(ot));
          TypeSymbol otc = ot.type.tsym;
          while (!(preciseMatch ? sym.isMemberOf(otc, types) : otc.isSubClass(sym.owner, types))) {
              do {
                  ots = ots.tail;
                  if (ots.isEmpty()) {
                      log.error(pos, Errors.NoEnclInstanceOfTypeInScope(c));
                      return tree;
                  }
                  ot = ots.head;
              } while (ot.owner != otc);
              tree = access(make.at(pos).Select(tree, ot));
              otc = ot.type.tsym;
          }
          return tree;
      }
  
      /** Return tree simulating the assignment {@code this.name = name}, where
       *  name is the name of a free variable.
       */
      JCStatement initField(int pos, Symbol rhs, Symbol lhs) {
          Assert.check(rhs.owner.kind == MTH);
          Assert.check(rhs.owner.owner == lhs.owner);
          make.at(pos);
          return
              make.Exec(
                  make.Assign(
                      make.Select(make.This(lhs.owner.erasure(types)), lhs),
                      make.Ident(rhs)).setType(lhs.erasure(types)));
      }
  
      /** Return tree simulating the assignment {@code this.this$n = this$n}.
       */
      JCStatement initOuterThis(int pos) {
          VarSymbol rhs = outerThisStack.head;
          Assert.check(rhs.owner.kind == MTH);
          VarSymbol lhs = outerThisStack.tail.head;
          Assert.check(rhs.owner.owner == lhs.owner);
          make.at(pos);
          return
              make.Exec(
                  make.Assign(
                      make.Select(make.This(lhs.owner.erasure(types)), lhs),
                      make.Ident(rhs)).setType(lhs.erasure(types)));
      }
  
  /**************************************************************************
   * Code for .class
   *************************************************************************/
  
      /** Return the symbol of a class to contain a cache of
       *  compiler-generated statics such as class$ and the
       *  $assertionsDisabled flag.  We create an anonymous nested class
       *  (unless one already exists) and return its symbol.  However,
       *  for backward compatibility in 1.4 and earlier we use the
       *  top-level class itself.
       */
      private ClassSymbol outerCacheClass() {
          ClassSymbol clazz = outermostClassDef.sym;
          Scope s = clazz.members();
          for (Symbol sym : s.getSymbols(NON_RECURSIVE))
              if (sym.kind == TYP &&
                  sym.name == names.empty &&
                  (sym.flags() & INTERFACE) == 0) return (ClassSymbol) sym;
          return makeEmptyClass(STATIC | SYNTHETIC, clazz).sym;
      }
  
      /** Create an attributed tree of the form left.name(). */
      private JCMethodInvocation makeCall(JCExpression left, Name name, List<JCExpression> args) {
          Assert.checkNonNull(left.type);
          Symbol funcsym = lookupMethod(make_pos, name, left.type,
                                        TreeInfo.types(args));
          return make.App(make.Select(left, funcsym), args);
      }
  
      /** The tree simulating a T.class expression.
       *  @param clazz      The tree identifying type T.
       */
      private JCExpression classOf(JCTree clazz) {
          return classOfType(clazz.type, clazz.pos());
      }
  
      private JCExpression classOfType(Type type, DiagnosticPosition pos) {
          switch (type.getTag()) {
          case BYTE: case SHORT: case CHAR: case INT: case LONG: case FLOAT:
          case DOUBLE: case BOOLEAN: case VOID:
              // replace with <BoxedClass>.TYPE
              ClassSymbol c = types.boxedClass(type);
              Symbol typeSym =
                  rs.accessBase(
                      rs.findIdentInType(pos, attrEnv, c.type, names.TYPE, KindSelector.VAR),
                      pos, c.type, names.TYPE, true);
              if (typeSym.kind == VAR)
                  ((VarSymbol)typeSym).getConstValue(); // ensure initializer is evaluated
              return make.QualIdent(typeSym);
          case CLASS: case ARRAY:
                  VarSymbol sym = new VarSymbol(
                          STATIC | PUBLIC | FINAL, names._class,
                          syms.classType, type.tsym);
                  return make_at(pos).Select(make.Type(type), sym);
          default:
              throw new AssertionError();
          }
      }
  
  /**************************************************************************
   * Code for enabling/disabling assertions.
   *************************************************************************/
  
      private ClassSymbol assertionsDisabledClassCache;
  
      /**Used to create an auxiliary class to hold $assertionsDisabled for interfaces.
       */
      private ClassSymbol assertionsDisabledClass() {
          if (assertionsDisabledClassCache != null) return assertionsDisabledClassCache;
  
          assertionsDisabledClassCache = makeEmptyClass(STATIC | SYNTHETIC, outermostClassDef.sym).sym;
  
          return assertionsDisabledClassCache;
      }
  
      // This code is not particularly robust if the user has
      // previously declared a member named '$assertionsDisabled'.
      // The same faulty idiom also appears in the translation of
      // class literals above.  We should report an error if a
      // previous declaration is not synthetic.
  
      private JCExpression assertFlagTest(DiagnosticPosition pos) {
          // Outermost class may be either true class or an interface.
          ClassSymbol outermostClass = outermostClassDef.sym;
  
          //only classes can hold a non-public field, look for a usable one:
          ClassSymbol container = !currentClass.isInterface() ? currentClass :
                  assertionsDisabledClass();
  
          VarSymbol assertDisabledSym =
              (VarSymbol)lookupSynthetic(dollarAssertionsDisabled,
                                         container.members());
          if (assertDisabledSym == null) {
              assertDisabledSym =
                  new VarSymbol(STATIC | FINAL | SYNTHETIC,
                                dollarAssertionsDisabled,
                                syms.booleanType,
                                container);
              enterSynthetic(pos, assertDisabledSym, container.members());
              Symbol desiredAssertionStatusSym = lookupMethod(pos,
                                                              names.desiredAssertionStatus,
                                                              types.erasure(syms.classType),
                                                              List.nil());
              JCClassDecl containerDef = classDef(container);
              make_at(containerDef.pos());
              JCExpression notStatus = makeUnary(NOT, make.App(make.Select(
                      classOfType(types.erasure(outermostClass.type),
                                  containerDef.pos()),
                      desiredAssertionStatusSym)));
              JCVariableDecl assertDisabledDef = make.VarDef(assertDisabledSym,
                                                     notStatus);
              containerDef.defs = containerDef.defs.prepend(assertDisabledDef);
  
              if (currentClass.isInterface()) {
                  //need to load the assertions enabled/disabled state while
                  //initializing the interface:
                  JCClassDecl currentClassDef = classDef(currentClass);
                  make_at(currentClassDef.pos());
                  JCStatement dummy = make.If(make.QualIdent(assertDisabledSym), make.Skip(), null);
                  JCBlock clinit = make.Block(STATIC, List.of(dummy));
                  currentClassDef.defs = currentClassDef.defs.prepend(clinit);
              }
          }
          make_at(pos);
          return makeUnary(NOT, make.Ident(assertDisabledSym));
      }
  
  
  /**************************************************************************
   * Building blocks for let expressions
   *************************************************************************/
  
      interface TreeBuilder {
          JCExpression build(JCExpression arg);
      }
  
      /** Construct an expression using the builder, with the given rval
       *  expression as an argument to the builder.  However, the rval
       *  expression must be computed only once, even if used multiple
       *  times in the result of the builder.  We do that by
       *  constructing a "let" expression that saves the rvalue into a
       *  temporary variable and then uses the temporary variable in
       *  place of the expression built by the builder.  The complete
       *  resulting expression is of the form
       *  <pre>
       *    (let <b>TYPE</b> <b>TEMP</b> = <b>RVAL</b>;
       *     in (<b>BUILDER</b>(<b>TEMP</b>)))
       *  </pre>
       *  where <code><b>TEMP</b></code> is a newly declared variable
       *  in the let expression.
       */
      JCExpression abstractRval(JCExpression rval, Type type, TreeBuilder builder) {
          rval = TreeInfo.skipParens(rval);
          switch (rval.getTag()) {
          case LITERAL:
              return builder.build(rval);
          case IDENT:
              JCIdent id = (JCIdent) rval;
              if ((id.sym.flags() & FINAL) != 0 && id.sym.owner.kind == MTH)
                  return builder.build(rval);
          }
          Name name = TreeInfo.name(rval);
          if (name == names._super || name == names._this)
              return builder.build(rval);
          VarSymbol var =
              new VarSymbol(FINAL|SYNTHETIC,
                            names.fromString(
                                            target.syntheticNameChar()
                                            + "" + rval.hashCode()),
                                        type,
                                        currentMethodSym);
          rval = convert(rval,type);
          JCVariableDecl def = make.VarDef(var, rval); // XXX cast
          JCExpression built = builder.build(make.Ident(var));
          JCExpression res = make.LetExpr(def, built);
          res.type = built.type;
          return res;
      }
  
      // same as above, with the type of the temporary variable computed
      JCExpression abstractRval(JCExpression rval, TreeBuilder builder) {
          return abstractRval(rval, rval.type, builder);
      }
  
      // same as above, but for an expression that may be used as either
      // an rvalue or an lvalue.  This requires special handling for
      // Select expressions, where we place the left-hand-side of the
      // select in a temporary, and for Indexed expressions, where we
      // place both the indexed expression and the index value in temps.
      JCExpression abstractLval(JCExpression lval, final TreeBuilder builder) {
          lval = TreeInfo.skipParens(lval);
          switch (lval.getTag()) {
          case IDENT:
              return builder.build(lval);
          case SELECT: {
              final JCFieldAccess s = (JCFieldAccess)lval;
              Symbol lid = TreeInfo.symbol(s.selected);
              if (lid != null && lid.kind == TYP) return builder.build(lval);
              return abstractRval(s.selected, selected -> builder.build(make.Select(selected, s.sym)));
          }
          case INDEXED: {
              final JCArrayAccess i = (JCArrayAccess)lval;
              return abstractRval(i.indexed, indexed -> abstractRval(i.index, syms.intType, index -> {
                  JCExpression newLval = make.Indexed(indexed, index);
                  newLval.setType(i.type);
                  return builder.build(newLval);
              }));
          }
          case TYPECAST: {
              return abstractLval(((JCTypeCast)lval).expr, builder);
          }
          }
          throw new AssertionError(lval);
      }
  
      // evaluate and discard the first expression, then evaluate the second.
      JCExpression makeComma(final JCExpression expr1, final JCExpression expr2) {
          JCExpression res = make.LetExpr(List.of(make.Exec(expr1)), expr2);
          res.type = expr2.type;
          return res;
      }
  
  /**************************************************************************
   * Translation methods
   *************************************************************************/
  
      /** Visitor argument: enclosing operator node.
       */
      private JCExpression enclOp;
  
      /** Visitor method: Translate a single node.
       *  Attach the source position from the old tree to its replacement tree.
       */
      @Override
      public <T extends JCTree> T translate(T tree) {
          if (tree == null) {
              return null;
          } else {
              make_at(tree.pos());
              T result = super.translate(tree);
              if (endPosTable != null && result != tree) {
                  endPosTable.replaceTree(tree, result);
              }
              return result;
          }
      }
  
      /** Visitor method: Translate a single node, boxing or unboxing if needed.
       */
      public <T extends JCExpression> T translate(T tree, Type type) {
          return (tree == null) ? null : boxIfNeeded(translate(tree), type);
      }
  
      /** Visitor method: Translate tree.
       */
      public <T extends JCTree> T translate(T tree, JCExpression enclOp) {
          JCExpression prevEnclOp = this.enclOp;
          this.enclOp = enclOp;
          T res = translate(tree);
          this.enclOp = prevEnclOp;
          return res;
      }
  
      /** Visitor method: Translate list of trees.
       */
      public <T extends JCExpression> List<T> translate(List<T> trees, Type type) {
          if (trees == null) return null;
          for (List<T> l = trees; l.nonEmpty(); l = l.tail)
              l.head = translate(l.head, type);
          return trees;
      }
  
      public void visitPackageDef(JCPackageDecl tree) {
          if (!needPackageInfoClass(tree))
                          return;
  
          long flags = Flags.ABSTRACT | Flags.INTERFACE;
          // package-info is marked SYNTHETIC in JDK 1.6 and later releases
          flags = flags | Flags.SYNTHETIC;
          ClassSymbol c = tree.packge.package_info;
          c.setAttributes(tree.packge);
          c.flags_field |= flags;
          ClassType ctype = (ClassType) c.type;
          ctype.supertype_field = syms.objectType;
          ctype.interfaces_field = List.nil();
          createInfoClass(tree.annotations, c);
      }
      // where
      private boolean needPackageInfoClass(JCPackageDecl pd) {
          switch (pkginfoOpt) {
              case ALWAYS:
                  return true;
              case LEGACY:
                  return pd.getAnnotations().nonEmpty();
              case NONEMPTY:
                  for (Attribute.Compound a :
                           pd.packge.getDeclarationAttributes()) {
                      Attribute.RetentionPolicy p = types.getRetention(a);
                      if (p != Attribute.RetentionPolicy.SOURCE)
                          return true;
                  }
                  return false;
          }
          throw new AssertionError();
      }
  
      public void visitModuleDef(JCModuleDecl tree) {
          ModuleSymbol msym = tree.sym;
          ClassSymbol c = msym.module_info;
          c.setAttributes(msym);
          c.flags_field |= Flags.MODULE;
          createInfoClass(List.nil(), tree.sym.module_info);
      }
  
      private void createInfoClass(List<JCAnnotation> annots, ClassSymbol c) {
          long flags = Flags.ABSTRACT | Flags.INTERFACE;
          JCClassDecl infoClass =
                  make.ClassDef(make.Modifiers(flags, annots),
                      c.name, List.nil(),
                      null, List.nil(), List.nil());
          infoClass.sym = c;
          translated.append(infoClass);
      }
  
      public void visitClassDef(JCClassDecl tree) {
          Env<AttrContext> prevEnv = attrEnv;
          ClassSymbol currentClassPrev = currentClass;
          MethodSymbol currentMethodSymPrev = currentMethodSym;
  
          currentClass = tree.sym;
          currentMethodSym = null;
          attrEnv = typeEnvs.remove(currentClass);
          if (attrEnv == null)
              attrEnv = prevEnv;
  
          classdefs.put(currentClass, tree);
  
          Map<Symbol, Symbol> prevProxies = proxies;
          proxies = new HashMap<>(proxies);
          List<VarSymbol> prevOuterThisStack = outerThisStack;
  
          // If this is an enum definition
          Type sup;
          if ((tree.mods.flags & ENUM) != 0 &&
              (sup = types.supertype(currentClass.type)).tsym != null && (sup.tsym.flags() & ENUM) == 0)
              visitEnumDef(tree);
  
          if ((tree.mods.flags & RECORD) != 0) {
              visitRecordDef(tree);
          }
  
          // If this is a nested class, define a this$n field for
          // it and add to proxies.
          JCVariableDecl otdef = null;
          if (currentClass.hasOuterInstance())
              otdef = outerThisDef(tree.pos, currentClass);
  
          // If this is a local class, define proxies for all its free variables.
          List<JCVariableDecl> fvdefs = freevarDefs(
              tree.pos, freevars(currentClass), currentClass);
  
          // Recursively translate superclass, interfaces.
          tree.extending = translate(tree.extending);
          tree.implementing = translate(tree.implementing);
  
          if (currentClass.isDirectlyOrIndirectlyLocal()) {
              ClassSymbol encl = currentClass.owner.enclClass();
              if (encl.trans_local == null) {
                  encl.trans_local = List.nil();
              }
              encl.trans_local = encl.trans_local.prepend(currentClass);
          }
  
          // Recursively translate members, taking into account that new members
          // might be created during the translation and prepended to the member
          // list `tree.defs'.
          List<JCTree> seen = List.nil();
          while (tree.defs != seen) {
              List<JCTree> unseen = tree.defs;
              for (List<JCTree> l = unseen; l.nonEmpty() && l != seen; l = l.tail) {
                  JCTree outermostMemberDefPrev = outermostMemberDef;
                  if (outermostMemberDefPrev == null) outermostMemberDef = l.head;
                  l.head = translate(l.head);
                  outermostMemberDef = outermostMemberDefPrev;
              }
              seen = unseen;
          }
  
          // Convert a protected modifier to public, mask static modifier.
          if ((tree.mods.flags & PROTECTED) != 0) tree.mods.flags |= PUBLIC;
          tree.mods.flags &= ClassFlags;
  
          // Convert name to flat representation, replacing '.' by '$'.
          tree.name = Convert.shortName(currentClass.flatName());
  
          // Add this$n and free variables proxy definitions to class.
  
          for (List<JCVariableDecl> l = fvdefs; l.nonEmpty(); l = l.tail) {
              tree.defs = tree.defs.prepend(l.head);
              enterSynthetic(tree.pos(), l.head.sym, currentClass.members());
          }
          if (currentClass.hasOuterInstance()) {
              tree.defs = tree.defs.prepend(otdef);
              enterSynthetic(tree.pos(), otdef.sym, currentClass.members());
          }
  
          proxies = prevProxies;
          outerThisStack = prevOuterThisStack;
  
          // Append translated tree to `translated' queue.
          translated.append(tree);
  
          attrEnv = prevEnv;
          currentClass = currentClassPrev;
          currentMethodSym = currentMethodSymPrev;
  
          // Return empty block {} as a placeholder for an inner class.
          result = make_at(tree.pos()).Block(SYNTHETIC, List.nil());
      }
  
      List<JCTree> generateMandatedAccessors(JCClassDecl tree) {
          List<JCVariableDecl> fields = TreeInfo.recordFields(tree);
          return tree.sym.getRecordComponents().stream()
                  .filter(rc -> (rc.accessor.flags() & Flags.GENERATED_MEMBER) != 0)
                  .map(rc -> {
                      // we need to return the field not the record component
                      JCVariableDecl field = fields.stream().filter(f -> f.name == rc.name).findAny().get();
                      make_at(tree.pos());
                      return make.MethodDef(rc.accessor, make.Block(0,
                              List.of(make.Return(make.Ident(field)))));
                  }).collect(List.collector());
      }
  
      /** Translate an enum class. */
      private void visitEnumDef(JCClassDecl tree) {
          make_at(tree.pos());
  
          // add the supertype, if needed
          if (tree.extending == null)
              tree.extending = make.Type(types.supertype(tree.type));
  
          // classOfType adds a cache field to tree.defs
          JCExpression e_class = classOfType(tree.sym.type, tree.pos()).
              setType(types.erasure(syms.classType));
  
          // process each enumeration constant, adding implicit constructor parameters
          int nextOrdinal = 0;
          ListBuffer<JCExpression> values = new ListBuffer<>();
          ListBuffer<JCTree> enumDefs = new ListBuffer<>();
          ListBuffer<JCTree> otherDefs = new ListBuffer<>();
          for (List<JCTree> defs = tree.defs;
               defs.nonEmpty();
               defs=defs.tail) {
              if (defs.head.hasTag(VARDEF) && (((JCVariableDecl) defs.head).mods.flags & ENUM) != 0) {
                  JCVariableDecl var = (JCVariableDecl)defs.head;
                  visitEnumConstantDef(var, nextOrdinal++);
                  values.append(make.QualIdent(var.sym));
                  enumDefs.append(var);
              } else {
                  otherDefs.append(defs.head);
              }
          }
  
          // synthetic private static T[] $values() { return new T[] { a, b, c }; }
          // synthetic private static final T[] $VALUES = $values();
          Name valuesName = syntheticName(tree, "VALUES");
          Type arrayType = new ArrayType(types.erasure(tree.type), syms.arrayClass);
          VarSymbol valuesVar = new VarSymbol(PRIVATE|FINAL|STATIC|SYNTHETIC,
                                              valuesName,
                                              arrayType,
                                              tree.type.tsym);
          JCNewArray newArray = make.NewArray(make.Type(types.erasure(tree.type)),
                                            List.nil(),
                                            values.toList());
          newArray.type = arrayType;
  
          MethodSymbol valuesMethod = new MethodSymbol(PRIVATE|STATIC|SYNTHETIC,
                  syntheticName(tree, "values"),
                  new MethodType(List.nil(), arrayType, List.nil(), tree.type.tsym),
                  tree.type.tsym);
          enumDefs.append(make.MethodDef(valuesMethod, make.Block(0, List.of(make.Return(newArray)))));
          tree.sym.members().enter(valuesMethod);
  
          enumDefs.append(make.VarDef(valuesVar, make.App(make.QualIdent(valuesMethod))));
          tree.sym.members().enter(valuesVar);
  
          Symbol valuesSym = lookupMethod(tree.pos(), names.values,
                                          tree.type, List.nil());
          List<JCStatement> valuesBody;
          if (useClone()) {
              // return (T[]) $VALUES.clone();
              JCTypeCast valuesResult =
                  make.TypeCast(valuesSym.type.getReturnType(),
                                make.App(make.Select(make.Ident(valuesVar),
                                                     syms.arrayCloneMethod)));
              valuesBody = List.of(make.Return(valuesResult));
          } else {
              // template: T[] $result = new T[$values.length];
              Name resultName = syntheticName(tree, "result");
              VarSymbol resultVar = new VarSymbol(FINAL|SYNTHETIC,
                                                  resultName,
                                                  arrayType,
                                                  valuesSym);
              JCNewArray resultArray = make.NewArray(make.Type(types.erasure(tree.type)),
                                    List.of(make.Select(make.Ident(valuesVar), syms.lengthVar)),
                                    null);
              resultArray.type = arrayType;
              JCVariableDecl decl = make.VarDef(resultVar, resultArray);
  
              // template: System.arraycopy($VALUES, 0, $result, 0, $VALUES.length);
              if (systemArraycopyMethod == null) {
                  systemArraycopyMethod =
                      new MethodSymbol(PUBLIC | STATIC,
                                       names.fromString("arraycopy"),
                                       new MethodType(List.of(syms.objectType,
                                                              syms.intType,
                                                              syms.objectType,
                                                              syms.intType,
                                                              syms.intType),
                                                      syms.voidType,
                                                      List.nil(),
                                                      syms.methodClass),
                                       syms.systemType.tsym);
              }
              JCStatement copy =
                  make.Exec(make.App(make.Select(make.Ident(syms.systemType.tsym),
                                                 systemArraycopyMethod),
                            List.of(make.Ident(valuesVar), make.Literal(0),
                                    make.Ident(resultVar), make.Literal(0),
                                    make.Select(make.Ident(valuesVar), syms.lengthVar))));
  
              // template: return $result;
              JCStatement ret = make.Return(make.Ident(resultVar));
              valuesBody = List.of(decl, copy, ret);
          }
  
          JCMethodDecl valuesDef =
               make.MethodDef((MethodSymbol)valuesSym, make.Block(0, valuesBody));
  
          enumDefs.append(valuesDef);
  
          if (debugLower)
              System.err.println(tree.sym + ".valuesDef = " + valuesDef);
  
          /** The template for the following code is:
           *
           *     public static E valueOf(String name) {
           *         return (E)Enum.valueOf(E.class, name);
           *     }
           *
           *  where E is tree.sym
           */
          MethodSymbol valueOfSym = lookupMethod(tree.pos(),
                           names.valueOf,
                           tree.sym.type,
                           List.of(syms.stringType));
          Assert.check((valueOfSym.flags() & STATIC) != 0);
          VarSymbol nameArgSym = valueOfSym.params().head;
          JCIdent nameVal = make.Ident(nameArgSym);
          JCStatement enum_ValueOf =
              make.Return(make.TypeCast(tree.sym.type,
                                        makeCall(make.Ident(syms.enumSym),
                                                 names.valueOf,
                                                 List.of(e_class, nameVal))));
          JCMethodDecl valueOf = make.MethodDef(valueOfSym,
                                             make.Block(0, List.of(enum_ValueOf)));
          nameVal.sym = valueOf.params.head.sym;
          if (debugLower)
              System.err.println(tree.sym + ".valueOf = " + valueOf);
          enumDefs.append(valueOf);
  
          enumDefs.appendList(otherDefs.toList());
          tree.defs = enumDefs.toList();
      }
          // where
          private MethodSymbol systemArraycopyMethod;
          private boolean useClone() {
              try {
                  return syms.objectType.tsym.members().findFirst(names.clone) != null;
              }
              catch (CompletionFailure e) {
                  return false;
              }
          }
  
          private Name syntheticName(JCClassDecl tree, String baseName) {
              Name valuesName = names.fromString(target.syntheticNameChar() + baseName);
              while (tree.sym.members().findFirst(valuesName) != null) // avoid name clash
                  valuesName = names.fromString(valuesName + "" + target.syntheticNameChar());
              return valuesName;
          }
  
      /** Translate an enumeration constant and its initializer. */
      private void visitEnumConstantDef(JCVariableDecl var, int ordinal) {
          if (var.init instanceof JCNewClass) {
              JCNewClass varDef = (JCNewClass)var.init;
              varDef.args = varDef.args.
                  prepend(makeLit(syms.intType, ordinal)).
                  prepend(makeLit(syms.stringType, var.name.toString()));
          }
      }
  
      private List<VarSymbol> recordVars(Type t) {
          List<VarSymbol> vars = List.nil();
          while (!t.hasTag(NONE)) {
              if (t.hasTag(CLASS)) {
                  for (Symbol s : t.tsym.members().getSymbols(s -> s.kind == VAR && (s.flags() & RECORD) != 0)) {
                      vars = vars.prepend((VarSymbol)s);
                  }
              }
              t = types.supertype(t);
          }
          return vars;
      }
  
      /** Translate a record. */
      private void visitRecordDef(JCClassDecl tree) {
          make_at(tree.pos());
          List<VarSymbol> vars = recordVars(tree.type);
          MethodHandleSymbol[] getterMethHandles = new MethodHandleSymbol[vars.size()];
          int index = 0;
          for (VarSymbol var : vars) {
              if (var.owner != tree.sym) {
                  var = new VarSymbol(var.flags_field, var.name, var.type, tree.sym);
              }
              getterMethHandles[index] = var.asMethodHandle(true);
              index++;
          }
  
          tree.defs = tree.defs.appendList(generateMandatedAccessors(tree));
          tree.defs = tree.defs.appendList(List.of(
                  generateRecordMethod(tree, names.toString, vars, getterMethHandles),
                  generateRecordMethod(tree, names.hashCode, vars, getterMethHandles),
                  generateRecordMethod(tree, names.equals, vars, getterMethHandles)
          ));
      }
  
      JCTree generateRecordMethod(JCClassDecl tree, Name name, List<VarSymbol> vars, MethodHandleSymbol[] getterMethHandles) {
          make_at(tree.pos());
          boolean isEquals = name == names.equals;
          MethodSymbol msym = lookupMethod(tree.pos(),
                  name,
                  tree.sym.type,
                  isEquals ? List.of(syms.objectType) : List.nil());
          // compiler generated methods have the record flag set, user defined ones dont
          if ((msym.flags() & RECORD) != 0) {
              /* class java.lang.runtime.ObjectMethods provides a common bootstrap that provides a customized implementation
               * for methods: toString, hashCode and equals. Here we just need to generate and indy call to:
               * java.lang.runtime.ObjectMethods::bootstrap and provide: the record class, the record component names and
               * the accessors.
               */
              Name bootstrapName = names.bootstrap;
              LoadableConstant[] staticArgsValues = new LoadableConstant[2 + getterMethHandles.length];
              staticArgsValues[0] = (ClassType)tree.sym.type;
              String concatNames = vars.stream()
                      .map(v -> v.name)
                      .collect(Collectors.joining(";", "", ""));
              staticArgsValues[1] = LoadableConstant.String(concatNames);
              int index = 2;
              for (MethodHandleSymbol mho : getterMethHandles) {
                  staticArgsValues[index] = mho;
                  index++;
              }
  
              List<Type> staticArgTypes = List.of(syms.classType,
                      syms.stringType,
                      new ArrayType(syms.methodHandleType, syms.arrayClass));
  
              JCFieldAccess qualifier = makeIndyQualifier(syms.objectMethodsType, tree, msym,
                      List.of(syms.methodHandleLookupType,
                              syms.stringType,
                              syms.typeDescriptorType).appendList(staticArgTypes),
                      staticArgsValues, bootstrapName, name, false);
  
              VarSymbol _this = new VarSymbol(SYNTHETIC, names._this, tree.sym.type, tree.sym);
  
              JCMethodInvocation proxyCall;
              if (!isEquals) {
                  proxyCall = make.Apply(List.nil(), qualifier, List.of(make.Ident(_this)));
              } else {
                  VarSymbol o = msym.params.head;
                  o.adr = 0;
                  proxyCall = make.Apply(List.nil(), qualifier, List.of(make.Ident(_this), make.Ident(o)));
              }
              proxyCall.type = qualifier.type;
              return make.MethodDef(msym, make.Block(0, List.of(make.Return(proxyCall))));
          } else {
              return make.Block(SYNTHETIC, List.nil());
          }
      }
  
      private String argsTypeSig(List<Type> typeList) {
          LowerSignatureGenerator sg = new LowerSignatureGenerator();
          sg.assembleSig(typeList);
          return sg.toString();
      }
  
      /**
       * Signature Generation
       */
      private class LowerSignatureGenerator extends Types.SignatureGenerator {
  
          /**
           * An output buffer for type signatures.
           */
          StringBuilder sb = new StringBuilder();
  
          LowerSignatureGenerator() {
              super(types);
          }
  
          @Override
          protected void append(char ch) {
              sb.append(ch);
          }
  
          @Override
          protected void append(byte[] ba) {
              sb.append(new String(ba));
          }
  
          @Override
          protected void append(Name name) {
              sb.append(name.toString());
          }
  
          @Override
          public String toString() {
              return sb.toString();
          }
      }
  
      /**
       * Creates an indy qualifier, helpful to be part of an indy invocation
       * @param site                the site
       * @param tree                a class declaration tree
       * @param msym                the method symbol
       * @param staticArgTypes      the static argument types
       * @param staticArgValues     the static argument values
       * @param bootstrapName       the bootstrap name to look for
       * @param argName             normally bootstraps receives a method name as second argument, if you want that name
       *                            to be different to that of the bootstrap name pass a different name here
       * @param isStatic            is it static or not
       * @return                    a field access tree
       */
      JCFieldAccess makeIndyQualifier(
              Type site,
              JCClassDecl tree,
              MethodSymbol msym,
              List<Type> staticArgTypes,
              LoadableConstant[] staticArgValues,
              Name bootstrapName,
              Name argName,
              boolean isStatic) {
          Symbol bsm = rs.resolveInternalMethod(tree.pos(), attrEnv, site,
                  bootstrapName, staticArgTypes, List.nil());
  
          MethodType indyType = msym.type.asMethodType();
          indyType = new MethodType(
                  isStatic ? List.nil() : indyType.argtypes.prepend(tree.sym.type),
                  indyType.restype,
                  indyType.thrown,
                  syms.methodClass
          );
          DynamicMethodSymbol dynSym = new DynamicMethodSymbol(argName,
                  syms.noSymbol,
                  ((MethodSymbol)bsm).asHandle(),
                  indyType,
                  staticArgValues);
          JCFieldAccess qualifier = make.Select(make.QualIdent(site.tsym), argName);
          qualifier.sym = dynSym;
          qualifier.type = msym.type.asMethodType().restype;
          return qualifier;
      }
  
      public void visitMethodDef(JCMethodDecl tree) {
          if (tree.name == names.init && (currentClass.flags_field&ENUM) != 0) {
              // Add "String $enum$name, int $enum$ordinal" to the beginning of the
              // argument list for each constructor of an enum.
              JCVariableDecl nameParam = make_at(tree.pos()).
                  Param(names.fromString(target.syntheticNameChar() +
                                         "enum" + target.syntheticNameChar() + "name"),
                        syms.stringType, tree.sym);
              nameParam.mods.flags |= SYNTHETIC; nameParam.sym.flags_field |= SYNTHETIC;
              JCVariableDecl ordParam = make.
                  Param(names.fromString(target.syntheticNameChar() +
                                         "enum" + target.syntheticNameChar() +
                                         "ordinal"),
                        syms.intType, tree.sym);
              ordParam.mods.flags |= SYNTHETIC; ordParam.sym.flags_field |= SYNTHETIC;
  
              MethodSymbol m = tree.sym;
              tree.params = tree.params.prepend(ordParam).prepend(nameParam);
  
              m.extraParams = m.extraParams.prepend(ordParam.sym);
              m.extraParams = m.extraParams.prepend(nameParam.sym);
              Type olderasure = m.erasure(types);
              m.erasure_field = new MethodType(
                  olderasure.getParameterTypes().prepend(syms.intType).prepend(syms.stringType),
                  olderasure.getReturnType(),
                  olderasure.getThrownTypes(),
                  syms.methodClass);
          }
  
          JCMethodDecl prevMethodDef = currentMethodDef;
          MethodSymbol prevMethodSym = currentMethodSym;
          try {
              currentMethodDef = tree;
              currentMethodSym = tree.sym;
              visitMethodDefInternal(tree);
          } finally {
              currentMethodDef = prevMethodDef;
              currentMethodSym = prevMethodSym;
          }
      }
  
      private void visitMethodDefInternal(JCMethodDecl tree) {
          if (tree.name == names.init &&
              (currentClass.isInner() || currentClass.isDirectlyOrIndirectlyLocal())) {
              // We are seeing a constructor of an inner class.
              MethodSymbol m = tree.sym;
  
              // Push a new proxy scope for constructor parameters.
              // and create definitions for any this$n and proxy parameters.
              Map<Symbol, Symbol> prevProxies = proxies;
              proxies = new HashMap<>(proxies);
              List<VarSymbol> prevOuterThisStack = outerThisStack;
              List<VarSymbol> fvs = freevars(currentClass);
              JCVariableDecl otdef = null;
              if (currentClass.hasOuterInstance())
                  otdef = outerThisDef(tree.pos, m);
              List<JCVariableDecl> fvdefs = freevarDefs(tree.pos, fvs, m, PARAMETER);
  
              // Recursively translate result type, parameters and thrown list.
              tree.restype = translate(tree.restype);
              tree.params = translateVarDefs(tree.params);
              tree.thrown = translate(tree.thrown);
  
              // when compiling stubs, don't process body
              if (tree.body == null) {
                  result = tree;
                  return;
              }
  
              // Add this$n (if needed) in front of and free variables behind
              // constructor parameter list.
              tree.params = tree.params.appendList(fvdefs);
              if (currentClass.hasOuterInstance()) {
                  tree.params = tree.params.prepend(otdef);
              }
  
              // If this is an initial constructor, i.e., it does not start with
              // this(...), insert initializers for this$n and proxies
              // before (pre-1.4, after) the call to superclass constructor.
              JCStatement selfCall = translate(tree.body.stats.head);
  
              List<JCStatement> added = List.nil();
              if (fvs.nonEmpty()) {
                  List<Type> addedargtypes = List.nil();
                  for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail) {
                      m.capturedLocals =
                          m.capturedLocals.prepend((VarSymbol)
                                                  (proxies.get(l.head)));
                      if (TreeInfo.isInitialConstructor(tree)) {
                          added = added.prepend(
                            initField(tree.body.pos, proxies.get(l.head), prevProxies.get(l.head)));
                      }
                      addedargtypes = addedargtypes.prepend(l.head.erasure(types));
                  }
                  Type olderasure = m.erasure(types);
                  m.erasure_field = new MethodType(
                      olderasure.getParameterTypes().appendList(addedargtypes),
                      olderasure.getReturnType(),
                      olderasure.getThrownTypes(),
                      syms.methodClass);
              }
              if (currentClass.hasOuterInstance() &&
                  TreeInfo.isInitialConstructor(tree))
              {
                  added = added.prepend(initOuterThis(tree.body.pos));
              }
  
              // pop local variables from proxy stack
              proxies = prevProxies;
  
              // recursively translate following local statements and
              // combine with this- or super-call
              List<JCStatement> stats = translate(tree.body.stats.tail);
              if (stats != null) {
                  tree.body.stats = stats.prepend(selfCall).prependList(added);
              }
              outerThisStack = prevOuterThisStack;
          } else {
              Map<Symbol, Symbol> prevLambdaTranslationMap =
                      lambdaTranslationMap;
              try {
                  lambdaTranslationMap = (tree.sym.flags() & SYNTHETIC) != 0 &&
                          tree.sym.name.startsWith(names.lambda) ?
                          makeTranslationMap(tree) : null;
                  super.visitMethodDef(tree);
              } finally {
                  lambdaTranslationMap = prevLambdaTranslationMap;
              }
          }
          if (tree.name == names.init && (tree.sym.flags_field & Flags.COMPACT_RECORD_CONSTRUCTOR) != 0) {
              // lets find out if there is any field waiting to be initialized
              ListBuffer<VarSymbol> fields = new ListBuffer<>();
              for (Symbol sym : currentClass.getEnclosedElements()) {
                  if (sym.kind == Kinds.Kind.VAR && ((sym.flags() & RECORD) != 0))
                      fields.append((VarSymbol) sym);
              }
              for (VarSymbol field: fields) {
                  if ((field.flags_field & Flags.UNINITIALIZED_FIELD) != 0) {
                      VarSymbol param = tree.params.stream().filter(p -> p.name == field.name).findFirst().get().sym;
                      make.at(tree.pos);
                      tree.body.stats = tree.body.stats.append(
                              make.Exec(
                                      make.Assign(
                                              make.Select(make.This(field.owner.erasure(types)), field),
                                              make.Ident(param)).setType(field.erasure(types))));
                      // we don't need the flag at the field anymore
                      field.flags_field &= ~Flags.UNINITIALIZED_FIELD;
                  }
              }
          }
          result = tree;
      }
      //where
          private Map<Symbol, Symbol> makeTranslationMap(JCMethodDecl tree) {
              Map<Symbol, Symbol> translationMap = new HashMap<>();
              for (JCVariableDecl vd : tree.params) {
                  Symbol p = vd.sym;
                  if (p != p.baseSymbol()) {
                      translationMap.put(p.baseSymbol(), p);
                  }
              }
              return translationMap;
          }
  
      public void visitTypeCast(JCTypeCast tree) {
          tree.clazz = translate(tree.clazz);
          if (tree.type.isPrimitive() != tree.expr.type.isPrimitive())
              tree.expr = translate(tree.expr, tree.type);
          else
              tree.expr = translate(tree.expr);
          result = tree;
      }
  
      public void visitNewClass(JCNewClass tree) {
          ClassSymbol c = (ClassSymbol)tree.constructor.owner;
  
          // Box arguments, if necessary
          boolean isEnum = (tree.constructor.owner.flags() & ENUM) != 0;
          List<Type> argTypes = tree.constructor.type.getParameterTypes();
          if (isEnum) argTypes = argTypes.prepend(syms.intType).prepend(syms.stringType);
          tree.args = boxArgs(argTypes, tree.args, tree.varargsElement);
          tree.varargsElement = null;
  
          // If created class is local, add free variables after
          // explicit constructor arguments.
          if (c.isDirectlyOrIndirectlyLocal()) {
              tree.args = tree.args.appendList(loadFreevars(tree.pos(), freevars(c)));
          }
  
          // If an access constructor is used, append null as a last argument.
          Symbol constructor = accessConstructor(tree.pos(), tree.constructor);
          if (constructor != tree.constructor) {
              tree.args = tree.args.append(makeNull());
              tree.constructor = constructor;
          }
  
          // If created class has an outer instance, and new is qualified, pass
          // qualifier as first argument. If new is not qualified, pass the
          // correct outer instance as first argument.
          if (c.hasOuterInstance()) {
              JCExpression thisArg;
              if (tree.encl != null) {
                  thisArg = attr.makeNullCheck(translate(tree.encl));
                  thisArg.type = tree.encl.type;
              } else if (c.isDirectlyOrIndirectlyLocal()) {
                  // local class
                  thisArg = makeThis(tree.pos(), c.type.getEnclosingType().tsym);
              } else {
                  // nested class
                  thisArg = makeOwnerThis(tree.pos(), c, false);
              }
              tree.args = tree.args.prepend(thisArg);
          }
          tree.encl = null;
  
          // If we have an anonymous class, create its flat version, rather
          // than the class or interface following new.
          if (tree.def != null) {
              Map<Symbol, Symbol> prevLambdaTranslationMap = lambdaTranslationMap;
              try {
                  lambdaTranslationMap = null;
                  translate(tree.def);
              } finally {
                  lambdaTranslationMap = prevLambdaTranslationMap;
              }
  
              tree.clazz = access(make_at(tree.clazz.pos()).Ident(tree.def.sym));
              tree.def = null;
          } else {
              tree.clazz = access(c, tree.clazz, enclOp, false);
          }
          result = tree;
      }
  
      // Simplify conditionals with known constant controlling expressions.
      // This allows us to avoid generating supporting declarations for
      // the dead code, which will not be eliminated during code generation.
      // Note that Flow.isFalse and Flow.isTrue only return true
      // for constant expressions in the sense of JLS 15.27, which
      // are guaranteed to have no side-effects.  More aggressive
      // constant propagation would require that we take care to
      // preserve possible side-effects in the condition expression.
  
      // One common case is equality expressions involving a constant and null.
      // Since null is not a constant expression (because null cannot be
      // represented in the constant pool), equality checks involving null are
      // not captured by Flow.isTrue/isFalse.
      // Equality checks involving a constant and null, e.g.
      //     "" == null
      // are safe to simplify as no side-effects can occur.
  
      private boolean isTrue(JCTree exp) {
          if (exp.type.isTrue())
              return true;
          Boolean b = expValue(exp);
          return b == null ? false : b;
      }
      private boolean isFalse(JCTree exp) {
          if (exp.type.isFalse())
              return true;
          Boolean b = expValue(exp);
          return b == null ? false : !b;
      }
      /* look for (in)equality relations involving null.
       * return true - if expression is always true
       *       false - if expression is always false
       *        null - if expression cannot be eliminated
       */
      private Boolean expValue(JCTree exp) {
          while (exp.hasTag(PARENS))
              exp = ((JCParens)exp).expr;
  
          boolean eq;
          switch (exp.getTag()) {
          case EQ: eq = true;  break;
          case NE: eq = false; break;
          default:
              return null;
          }
  
          // we have a JCBinary(EQ|NE)
          // check if we have two literals (constants or null)
          JCBinary b = (JCBinary)exp;
          if (b.lhs.type.hasTag(BOT)) return expValueIsNull(eq, b.rhs);
          if (b.rhs.type.hasTag(BOT)) return expValueIsNull(eq, b.lhs);
          return null;
      }
      private Boolean expValueIsNull(boolean eq, JCTree t) {
          if (t.type.hasTag(BOT)) return Boolean.valueOf(eq);
          if (t.hasTag(LITERAL))  return Boolean.valueOf(!eq);
          return null;
      }
  
      /** Visitor method for conditional expressions.
       */
      @Override
      public void visitConditional(JCConditional tree) {
          JCTree cond = tree.cond = translate(tree.cond, syms.booleanType);
          if (isTrue(cond)) {
              result = convert(translate(tree.truepart, tree.type), tree.type);
              addPrunedInfo(cond);
          } else if (isFalse(cond)) {
              result = convert(translate(tree.falsepart, tree.type), tree.type);
              addPrunedInfo(cond);
          } else {
              // Condition is not a compile-time constant.
              tree.truepart = translate(tree.truepart, tree.type);
              tree.falsepart = translate(tree.falsepart, tree.type);
              result = tree;
          }
      }
  //where
      private JCExpression convert(JCExpression tree, Type pt) {
          if (tree.type == pt || tree.type.hasTag(BOT))
              return tree;
          JCExpression result = make_at(tree.pos()).TypeCast(make.Type(pt), tree);
          result.type = (tree.type.constValue() != null) ? cfolder.coerce(tree.type, pt)
                                                         : pt;
          return result;
      }
  
      /** Visitor method for if statements.
       */
      public void visitIf(JCIf tree) {
          JCTree cond = tree.cond = translate(tree.cond, syms.booleanType);
          if (isTrue(cond)) {
              result = translate(tree.thenpart);
              addPrunedInfo(cond);
          } else if (isFalse(cond)) {
              if (tree.elsepart != null) {
                  result = translate(tree.elsepart);
              } else {
                  result = make.Skip();
              }
              addPrunedInfo(cond);
          } else {
              // Condition is not a compile-time constant.
              tree.thenpart = translate(tree.thenpart);
              tree.elsepart = translate(tree.elsepart);
              result = tree;
          }
      }
  
      /** Visitor method for assert statements. Translate them away.
       */
      public void visitAssert(JCAssert tree) {
          tree.cond = translate(tree.cond, syms.booleanType);
          if (!tree.cond.type.isTrue()) {
              JCExpression cond = assertFlagTest(tree.pos());
              List<JCExpression> exnArgs = (tree.detail == null) ?
                  List.nil() : List.of(translate(tree.detail));
              if (!tree.cond.type.isFalse()) {
                  cond = makeBinary
                      (AND,
                       cond,
                       makeUnary(NOT, tree.cond));
              }
              result =
                  make.If(cond,
                          make_at(tree).
                             Throw(makeNewClass(syms.assertionErrorType, exnArgs)),
                          null);
          } else {
              result = make.Skip();
          }
      }
  
      public void visitApply(JCMethodInvocation tree) {
          Symbol meth = TreeInfo.symbol(tree.meth);
          List<Type> argtypes = meth.type.getParameterTypes();
          if (meth.name == names.init && meth.owner == syms.enumSym)
              argtypes = argtypes.tail.tail;
          tree.args = boxArgs(argtypes, tree.args, tree.varargsElement);
          tree.varargsElement = null;
          Name methName = TreeInfo.name(tree.meth);
          if (meth.name==names.init) {
              // We are seeing a this(...) or super(...) constructor call.
              // If an access constructor is used, append null as a last argument.
              Symbol constructor = accessConstructor(tree.pos(), meth);
              if (constructor != meth) {
                  tree.args = tree.args.append(makeNull());
                  TreeInfo.setSymbol(tree.meth, constructor);
              }
  
              // If we are calling a constructor of a local class, add
              // free variables after explicit constructor arguments.
              ClassSymbol c = (ClassSymbol)constructor.owner;
              if (c.isDirectlyOrIndirectlyLocal()) {
                  tree.args = tree.args.appendList(loadFreevars(tree.pos(), freevars(c)));
              }
  
              // If we are calling a constructor of an enum class, pass
              // along the name and ordinal arguments
              if ((c.flags_field&ENUM) != 0 || c.getQualifiedName() == names.java_lang_Enum) {
                  List<JCVariableDecl> params = currentMethodDef.params;
                  if (currentMethodSym.owner.hasOuterInstance())
                      params = params.tail; // drop this$n
                  if (params.isEmpty() || params.tail.isEmpty()) {
                      tree.args = tree.args.prepend(makeNull()).prepend(makeNull());
                  } else {
                      tree.args = tree.args
                          .prepend(make_at(tree.pos()).Ident(params.tail.head.sym)) // ordinal
                          .prepend(make.Ident(params.head.sym)); // name
                  }
              }
  
              // If we are calling a constructor of a class with an outer
              // instance, and the call
              // is qualified, pass qualifier as first argument in front of
              // the explicit constructor arguments. If the call
              // is not qualified, pass the correct outer instance as
              // first argument.
              if (c.hasOuterInstance()) {
                  JCExpression thisArg;
                  if (tree.meth.hasTag(SELECT)) {
                      thisArg = attr.
                          makeNullCheck(translate(((JCFieldAccess) tree.meth).selected));
                      tree.meth = make.Ident(constructor);
                      ((JCIdent) tree.meth).name = methName;
                  } else if (c.isDirectlyOrIndirectlyLocal() || methName == names._this){
                      // local class or this() call
                      thisArg = makeThis(tree.meth.pos(), c.type.getEnclosingType().tsym);
                  } else {
                      // super() call of nested class - never pick 'this'
                      thisArg = makeOwnerThisN(tree.meth.pos(), c, false);
                  }
                  tree.args = tree.args.prepend(thisArg);
              }
          } else {
              // We are seeing a normal method invocation; translate this as usual.
              tree.meth = translate(tree.meth);
  
              // If the translated method itself is an Apply tree, we are
              // seeing an access method invocation. In this case, append
              // the method arguments to the arguments of the access method.
              if (tree.meth.hasTag(APPLY)) {
                  JCMethodInvocation app = (JCMethodInvocation)tree.meth;
                  app.args = tree.args.prependList(app.args);
                  result = app;
                  return;
              }
          }
          result = tree;
      }
  
      List<JCExpression> boxArgs(List<Type> parameters, List<JCExpression> _args, Type varargsElement) {
          List<JCExpression> args = _args;
          if (parameters.isEmpty()) return args;
          boolean anyChanges = false;
          ListBuffer<JCExpression> result = new ListBuffer<>();
          while (parameters.tail.nonEmpty() && args.nonEmpty()) {
              JCExpression arg = translate(args.head, parameters.head);
              anyChanges |= (arg != args.head);
              result.append(arg);
              args = args.tail;
              parameters = parameters.tail;
          }
          Type parameter = parameters.head;
          if (varargsElement != null) {
              anyChanges = true;
              ListBuffer<JCExpression> elems = new ListBuffer<>();
              while (args.nonEmpty()) {
                  JCExpression arg = translate(args.head, varargsElement);
                  elems.append(arg);
                  args = args.tail;
              }
              JCNewArray boxedArgs = make.NewArray(make.Type(varargsElement),
                                                 List.nil(),
                                                 elems.toList());
              boxedArgs.type = new ArrayType(varargsElement, syms.arrayClass);
              result.append(boxedArgs);
          } else {
              if (args.length() != 1) throw new AssertionError(args);
              JCExpression arg = translate(args.head, parameter);
              anyChanges |= (arg != args.head);
              result.append(arg);
              if (!anyChanges) return _args;
          }
          return result.toList();
      }
  
      /** Expand a boxing or unboxing conversion if needed. */
      @SuppressWarnings("unchecked") // XXX unchecked
      <T extends JCExpression> T boxIfNeeded(T tree, Type type) {
          if (type == null)
              return tree;
          boolean havePrimitive = tree.type != null ? tree.type.isPrimitive() : false;
          if (havePrimitive == type.isPrimitive())
              return tree;
          if (havePrimitive) {
              Type unboxedTarget = types.unboxedType(type);
              if (!unboxedTarget.hasTag(NONE)) {
                  if (!types.isSubtype(tree.type, unboxedTarget)) //e.g. Character c = 89;
                      tree.type = unboxedTarget.constType(tree.type.constValue());
                  return (T)boxPrimitive(tree, types.erasure(type));
              } else {
                  tree = (T)boxPrimitive(tree);
              }
          } else {
              tree = (T)unbox(tree, type);
          }
          return tree;
      }
  
      /** Box up a single primitive expression. */
      JCExpression boxPrimitive(JCExpression tree) {
          return boxPrimitive(tree, types.boxedClass(tree.type).type);
      }
  
      /** Box up a single primitive expression. */
      JCExpression boxPrimitive(JCExpression tree, Type box) {
          make_at(tree.pos());
          Symbol valueOfSym = lookupMethod(tree.pos(),
                                           names.valueOf,
                                           box,
                                           List.<Type>nil()
                                           .prepend(tree.type));
          return make.App(make.QualIdent(valueOfSym), List.of(tree));
      }
  
      /** Unbox an object to a primitive value. */
      JCExpression unbox(JCExpression tree, Type primitive) {
          if (tree.type == null || tree.type.isErroneous())
              return tree;
          Type unboxedType = types.unboxedType(tree.type);
          if (unboxedType.hasTag(NONE)) {
              unboxedType = primitive;
              if (!unboxedType.isPrimitive())
                  throw new AssertionError(unboxedType);
              make_at(tree.pos());
              tree = make.TypeCast(types.boxedClass(unboxedType).type, tree);
          } else {
              // There must be a conversion from unboxedType to primitive.
              if (!types.isSubtype(unboxedType, primitive))
                  throw new AssertionError(tree);
          }
          // note: the "primitive" parameter is not used.  There muse be
          // a conversion from unboxedType to primitive.
          if (unboxedType.tsym == null)
              return tree;
          make_at(tree.pos());
          Symbol valueSym = lookupMethod(tree.pos(),
                                         unboxedType.tsym.name.append(names.Value), // x.intValue()
                                         tree.type,
                                         List.nil());
          return make.App(make.Select(tree, valueSym));
      }
  
      /** Visitor method for parenthesized expressions.
       *  If the subexpression has changed, omit the parens.
       */
      public void visitParens(JCParens tree) {
          JCTree expr = translate(tree.expr);
          result = ((expr == tree.expr) ? tree : expr);
      }
  
      public void visitIndexed(JCArrayAccess tree) {
          tree.indexed = translate(tree.indexed);
          tree.index = translate(tree.index, syms.intType);
          result = tree;
      }
  
      public void visitAssign(JCAssign tree) {
          tree.lhs = translate(tree.lhs, tree);
          tree.rhs = translate(tree.rhs, tree.lhs.type);
  
          // If translated left hand side is an Apply, we are
          // seeing an access method invocation. In this case, append
          // right hand side as last argument of the access method.
          if (tree.lhs.hasTag(APPLY)) {
              JCMethodInvocation app = (JCMethodInvocation)tree.lhs;
              app.args = List.of(tree.rhs).prependList(app.args);
              result = app;
          } else {
              result = tree;
          }
      }
  
      public void visitAssignop(final JCAssignOp tree) {
          final boolean boxingReq = !tree.lhs.type.isPrimitive() && !tree.lhs.type.isErroneous() &&
              tree.operator.type.getReturnType().isPrimitive();
  
          AssignopDependencyScanner depScanner = new AssignopDependencyScanner(tree);
          depScanner.scan(tree.rhs);
  
          if (boxingReq || depScanner.dependencyFound) {
              // boxing required; need to rewrite as x = (unbox typeof x)(x op y);
              // or if x == (typeof x)z then z = (unbox typeof x)((typeof x)z op y)
              // (but without recomputing x)
              JCTree newTree = abstractLval(tree.lhs, lhs -> {
                  Tag newTag = tree.getTag().noAssignOp();
                  // Erasure (TransTypes) can change the type of
                  // tree.lhs.  However, we can still get the
                  // unerased type of tree.lhs as it is stored
                  // in tree.type in Attr.
                  OperatorSymbol newOperator = operators.resolveBinary(tree,
                                                                newTag,
                                                                tree.type,
                                                                tree.rhs.type);
                  //Need to use the "lhs" at two places, once on the future left hand side
                  //and once in the future binary operator. But further processing may change
                  //the components of the tree in place (see visitSelect for e.g. <Class>.super.<ident>),
                  //so cloning the tree to avoid interference between the uses:
                  JCExpression expr = (JCExpression) lhs.clone();
                  if (expr.type != tree.type)
                      expr = make.TypeCast(tree.type, expr);
                  JCBinary opResult = make.Binary(newTag, expr, tree.rhs);
                  opResult.operator = newOperator;
                  opResult.type = newOperator.type.getReturnType();
                  JCExpression newRhs = boxingReq ?
                      make.TypeCast(types.unboxedType(tree.type), opResult) :
                      opResult;
                  return make.Assign(lhs, newRhs).setType(tree.type);
              });
              result = translate(newTree);
              return;
          }
          tree.lhs = translate(tree.lhs, tree);
          tree.rhs = translate(tree.rhs, tree.operator.type.getParameterTypes().tail.head);
  
          // If translated left hand side is an Apply, we are
          // seeing an access method invocation. In this case, append
          // right hand side as last argument of the access method.
          if (tree.lhs.hasTag(APPLY)) {
              JCMethodInvocation app = (JCMethodInvocation)tree.lhs;
              // if operation is a += on strings,
              // make sure to convert argument to string
              JCExpression rhs = tree.operator.opcode == string_add
                ? makeString(tree.rhs)
                : tree.rhs;
              app.args = List.of(rhs).prependList(app.args);
              result = app;
          } else {
              result = tree;
          }
      }
  
      class AssignopDependencyScanner extends TreeScanner {
  
          Symbol sym;
          boolean dependencyFound = false;
  
          AssignopDependencyScanner(JCAssignOp tree) {
              this.sym = TreeInfo.symbol(tree.lhs);
          }
  
          @Override
          public void scan(JCTree tree) {
              if (tree != null && sym != null) {
                  tree.accept(this);
              }
          }
  
          @Override
          public void visitAssignop(JCAssignOp tree) {
              if (TreeInfo.symbol(tree.lhs) == sym) {
                  dependencyFound = true;
                  return;
              }
              super.visitAssignop(tree);
          }
  
          @Override
          public void visitUnary(JCUnary tree) {
              if (TreeInfo.symbol(tree.arg) == sym) {
                  dependencyFound = true;
                  return;
              }
              super.visitUnary(tree);
          }
      }
  
      /** Lower a tree of the form e++ or e-- where e is an object type */
      JCExpression lowerBoxedPostop(final JCUnary tree) {
          // translate to tmp1=lval(e); tmp2=tmp1; tmp1 OP 1; tmp2
          // or
          // translate to tmp1=lval(e); tmp2=tmp1; (typeof tree)tmp1 OP 1; tmp2
          // where OP is += or -=
          final boolean cast = TreeInfo.skipParens(tree.arg).hasTag(TYPECAST);
          return abstractLval(tree.arg, tmp1 -> abstractRval(tmp1, tree.arg.type, tmp2 -> {
              Tag opcode = (tree.hasTag(POSTINC))
                  ? PLUS_ASG : MINUS_ASG;
              //"tmp1" and "tmp2" may refer to the same instance
              //(for e.g. <Class>.super.<ident>). But further processing may
              //change the components of the tree in place (see visitSelect),
              //so cloning the tree to avoid interference between the two uses:
              JCExpression lhs = (JCExpression)tmp1.clone();
              lhs = cast
                  ? make.TypeCast(tree.arg.type, lhs)
                  : lhs;
              JCExpression update = makeAssignop(opcode,
                                           lhs,
                                           make.Literal(1));
              return makeComma(update, tmp2);
          }));
      }
  
      public void visitUnary(JCUnary tree) {
          boolean isUpdateOperator = tree.getTag().isIncOrDecUnaryOp();
          if (isUpdateOperator && !tree.arg.type.isPrimitive()) {
              switch(tree.getTag()) {
              case PREINC:            // ++ e
                      // translate to e += 1
              case PREDEC:            // -- e
                      // translate to e -= 1
                  {
                      JCTree.Tag opcode = (tree.hasTag(PREINC))
                          ? PLUS_ASG : MINUS_ASG;
                      JCAssignOp newTree = makeAssignop(opcode,
                                                      tree.arg,
                                                      make.Literal(1));
                      result = translate(newTree, tree.type);
                      return;
                  }
              case POSTINC:           // e ++
              case POSTDEC:           // e --
                  {
                      result = translate(lowerBoxedPostop(tree), tree.type);
                      return;
                  }
              }
              throw new AssertionError(tree);
          }
  
          tree.arg = boxIfNeeded(translate(tree.arg, tree), tree.type);
  
          if (tree.hasTag(NOT) && tree.arg.type.constValue() != null) {
              tree.type = cfolder.fold1(bool_not, tree.arg.type);
          }
  
          // If translated left hand side is an Apply, we are
          // seeing an access method invocation. In this case, return
          // that access method invocation as result.
          if (isUpdateOperator && tree.arg.hasTag(APPLY)) {
              result = tree.arg;
          } else {
              result = tree;
          }
      }
  
      public void visitBinary(JCBinary tree) {
          List<Type> formals = tree.operator.type.getParameterTypes();
          JCTree lhs = tree.lhs = translate(tree.lhs, formals.head);
          switch (tree.getTag()) {
          case OR:
              if (isTrue(lhs)) {
                  result = lhs;
                  return;
              }
              if (isFalse(lhs)) {
                  result = translate(tree.rhs, formals.tail.head);
                  return;
              }
              break;
          case AND:
              if (isFalse(lhs)) {
                  result = lhs;
                  return;
              }
              if (isTrue(lhs)) {
                  result = translate(tree.rhs, formals.tail.head);
                  return;
              }
              break;
          }
          tree.rhs = translate(tree.rhs, formals.tail.head);
          result = tree;
      }
  
      public void visitIdent(JCIdent tree) {
          result = access(tree.sym, tree, enclOp, false);
      }
  
      /** Translate away the foreach loop.  */
      public void visitForeachLoop(JCEnhancedForLoop tree) {
          if (types.elemtype(tree.expr.type) == null)
              visitIterableForeachLoop(tree);
          else
              visitArrayForeachLoop(tree);
      }
          // where
          /**
           * A statement of the form
           *
           * <pre>
           *     for ( T v : arrayexpr ) stmt;
           * </pre>
           *
           * (where arrayexpr is of an array type) gets translated to
           *
           * <pre>{@code
           *     for ( { arraytype #arr = arrayexpr;
           *             int #len = array.length;
           *             int #i = 0; };
           *           #i < #len; i$++ ) {
           *         T v = arr$[#i];
           *         stmt;
           *     }
           * }</pre>
           *
           * where #arr, #len, and #i are freshly named synthetic local variables.
           */
          private void visitArrayForeachLoop(JCEnhancedForLoop tree) {
              make_at(tree.expr.pos());
              VarSymbol arraycache = new VarSymbol(SYNTHETIC,
                                                   names.fromString("arr" + target.syntheticNameChar()),
                                                   tree.expr.type,
                                                   currentMethodSym);
              JCStatement arraycachedef = make.VarDef(arraycache, tree.expr);
              VarSymbol lencache = new VarSymbol(SYNTHETIC,
                                                 names.fromString("len" + target.syntheticNameChar()),
                                                 syms.intType,
                                                 currentMethodSym);
              JCStatement lencachedef = make.
                  VarDef(lencache, make.Select(make.Ident(arraycache), syms.lengthVar));
              VarSymbol index = new VarSymbol(SYNTHETIC,
                                              names.fromString("i" + target.syntheticNameChar()),
                                              syms.intType,
                                              currentMethodSym);
  
              JCVariableDecl indexdef = make.VarDef(index, make.Literal(INT, 0));
              indexdef.init.type = indexdef.type = syms.intType.constType(0);
  
              List<JCStatement> loopinit = List.of(arraycachedef, lencachedef, indexdef);
              JCBinary cond = makeBinary(LT, make.Ident(index), make.Ident(lencache));
  
              JCExpressionStatement step = make.Exec(makeUnary(PREINC, make.Ident(index)));
  
              Type elemtype = types.elemtype(tree.expr.type);
              JCExpression loopvarinit = make.Indexed(make.Ident(arraycache),
                                                      make.Ident(index)).setType(elemtype);
              JCVariableDecl loopvardef = (JCVariableDecl)make.VarDef(tree.var.mods,
                                                    tree.var.name,
                                                    tree.var.vartype,
                                                    loopvarinit).setType(tree.var.type);
              loopvardef.sym = tree.var.sym;
              JCBlock body = make.
                  Block(0, List.of(loopvardef, tree.body));
  
              result = translate(make.
                                 ForLoop(loopinit,
                                         cond,
                                         List.of(step),
                                         body));
              patchTargets(body, tree, result);
          }
          /** Patch up break and continue targets. */
          private void patchTargets(JCTree body, final JCTree src, final JCTree dest) {
              class Patcher extends TreeScanner {
                  public void visitBreak(JCBreak tree) {
                      if (tree.target == src)
                          tree.target = dest;
                  }
                  public void visitYield(JCYield tree) {
                      if (tree.target == src)
                          tree.target = dest;
                      scan(tree.value);
                  }
                  public void visitContinue(JCContinue tree) {
                      if (tree.target == src)
                          tree.target = dest;
                  }
                  public void visitClassDef(JCClassDecl tree) {}
              }
              new Patcher().scan(body);
          }
          /**
           * A statement of the form
           *
           * <pre>
           *     for ( T v : coll ) stmt ;
           * </pre>
           *
           * (where coll implements {@code Iterable<? extends T>}) gets translated to
           *
           * <pre>{@code
           *     for ( Iterator<? extends T> #i = coll.iterator(); #i.hasNext(); ) {
           *         T v = (T) #i.next();
           *         stmt;
           *     }
           * }</pre>
           *
           * where #i is a freshly named synthetic local variable.
           */
          private void visitIterableForeachLoop(JCEnhancedForLoop tree) {
              make_at(tree.expr.pos());
              Type iteratorTarget = syms.objectType;
              Type iterableType = types.asSuper(types.cvarUpperBound(tree.expr.type),
                                                syms.iterableType.tsym);
              if (iterableType != null && iterableType.getTypeArguments().nonEmpty())
                  iteratorTarget = types.erasure(iterableType.getTypeArguments().head);
              Type eType = types.skipTypeVars(tree.expr.type, false);
              tree.expr.type = types.erasure(eType);
              if (eType.isCompound())
                  tree.expr = make.TypeCast(types.erasure(iterableType), tree.expr);
              Symbol iterator = lookupMethod(tree.expr.pos(),
                                             names.iterator,
                                             eType,
                                             List.nil());
              VarSymbol itvar = new VarSymbol(SYNTHETIC, names.fromString("i" + target.syntheticNameChar()),
                                              types.erasure(types.asSuper(iterator.type.getReturnType(), syms.iteratorType.tsym)),
                                              currentMethodSym);
  
               JCStatement init = make.
                  VarDef(itvar, make.App(make.Select(tree.expr, iterator)
                       .setType(types.erasure(iterator.type))));
  
              Symbol hasNext = lookupMethod(tree.expr.pos(),
                                            names.hasNext,
                                            itvar.type,
                                            List.nil());
              JCMethodInvocation cond = make.App(make.Select(make.Ident(itvar), hasNext));
              Symbol next = lookupMethod(tree.expr.pos(),
                                         names.next,
                                         itvar.type,
                                         List.nil());
              JCExpression vardefinit = make.App(make.Select(make.Ident(itvar), next));
              if (tree.var.type.isPrimitive())
                  vardefinit = make.TypeCast(types.cvarUpperBound(iteratorTarget), vardefinit);
              else
                  vardefinit = make.TypeCast(tree.var.type, vardefinit);
              JCVariableDecl indexDef = (JCVariableDecl)make.VarDef(tree.var.mods,
                                                    tree.var.name,
                                                    tree.var.vartype,
                                                    vardefinit).setType(tree.var.type);
              indexDef.sym = tree.var.sym;
              JCBlock body = make.Block(0, List.of(indexDef, tree.body));
              body.endpos = TreeInfo.endPos(tree.body);
              result = translate(make.
                  ForLoop(List.of(init),
                          cond,
                          List.nil(),
                          body));
              patchTargets(body, tree, result);
          }
  
      public void visitVarDef(JCVariableDecl tree) {
          MethodSymbol oldMethodSym = currentMethodSym;
          tree.mods = translate(tree.mods);
          tree.vartype = translate(tree.vartype);
          if (currentMethodSym == null) {
              // A class or instance field initializer.
              currentMethodSym =
                  new MethodSymbol((tree.mods.flags&STATIC) | BLOCK,
                                   names.empty, null,
                                   currentClass);
          }
          if (tree.init != null) tree.init = translate(tree.init, tree.type);
          result = tree;
          currentMethodSym = oldMethodSym;
      }
  
      public void visitBlock(JCBlock tree) {
          MethodSymbol oldMethodSym = currentMethodSym;
          if (currentMethodSym == null) {
              // Block is a static or instance initializer.
              currentMethodSym =
                  new MethodSymbol(tree.flags | BLOCK,
                                   names.empty, null,
                                   currentClass);
          }
          super.visitBlock(tree);
          currentMethodSym = oldMethodSym;
      }
  
      public void visitDoLoop(JCDoWhileLoop tree) {
          tree.body = translate(tree.body);
          tree.cond = translate(tree.cond, syms.booleanType);
          result = tree;
      }
  
      public void visitWhileLoop(JCWhileLoop tree) {
          tree.cond = translate(tree.cond, syms.booleanType);
          tree.body = translate(tree.body);
          result = tree;
      }
  
      public void visitForLoop(JCForLoop tree) {
          tree.init = translate(tree.init);
          if (tree.cond != null)
              tree.cond = translate(tree.cond, syms.booleanType);
          tree.step = translate(tree.step);
          tree.body = translate(tree.body);
          result = tree;
      }
  
      public void visitReturn(JCReturn tree) {
          if (tree.expr != null)
              tree.expr = translate(tree.expr,
                                    types.erasure(currentMethodDef
                                                  .restype.type));
          result = tree;
      }
  
      public void visitSwitch(JCSwitch tree) {
          List<JCCase> cases = tree.patternSwitch ? addDefaultIfNeeded(tree.cases) : tree.cases;
          handleSwitch(tree, tree.selector, cases);
      }
  
      @Override
      public void visitSwitchExpression(JCSwitchExpression tree) {
          List<JCCase> cases = addDefaultIfNeeded(tree.cases);
          handleSwitch(tree, tree.selector, cases);
      }
  
      private List<JCCase> addDefaultIfNeeded(List<JCCase> cases) {
          if (cases.stream().flatMap(c -> c.labels.stream()).noneMatch(p -> p.hasTag(Tag.DEFAULTCASELABEL))) {
              JCThrow thr = make.Throw(makeNewClass(syms.incompatibleClassChangeErrorType,
                                                    List.nil()));
              JCCase c = make.Case(JCCase.STATEMENT, List.of(make.DefaultCaseLabel()), List.of(thr), null);
              cases = cases.prepend(c);
          }
  
          return cases;
      }
  
      private void handleSwitch(JCTree tree, JCExpression selector, List<JCCase> cases) {
          //expand multiple label cases:
          ListBuffer<JCCase> convertedCases = new ListBuffer<>();
  
          for (JCCase c : cases) {
              switch (c.labels.size()) {
                  case 0: //default
                  case 1: //single label
                      convertedCases.append(c);
                      break;
                  default: //multiple labels, expand:
                      //case C1, C2, C3: ...
                      //=>
                      //case C1:
                      //case C2:
                      //case C3: ...
                      List<JCCaseLabel> patterns = c.labels;
                      while (patterns.tail.nonEmpty()) {
                          convertedCases.append(make_at(c.pos()).Case(JCCase.STATEMENT,
                                                             List.of(patterns.head),
                                                             List.nil(),
                                                             null));
                          patterns = patterns.tail;
                      }
                      c.labels = patterns;
                      convertedCases.append(c);
                      break;
              }
          }
  
          for (JCCase c : convertedCases) {
              if (c.caseKind == JCCase.RULE && c.completesNormally) {
                  JCBreak b = make.at(TreeInfo.endPos(c.stats.last())).Break(null);
                  b.target = tree;
                  c.stats = c.stats.append(b);
              }
          }
  
          cases = convertedCases.toList();
  
          Type selsuper = types.supertype(selector.type);
          boolean enumSwitch = selsuper != null &&
              (selector.type.tsym.flags() & ENUM) != 0;
          boolean stringSwitch = selsuper != null &&
              types.isSameType(selector.type, syms.stringType);
          boolean boxedSwitch = !enumSwitch && !stringSwitch && !selector.type.isPrimitive();
          selector = translate(selector, selector.type);
          cases = translateCases(cases);
          if (tree.hasTag(SWITCH)) {
              ((JCSwitch) tree).selector = selector;
              ((JCSwitch) tree).cases = cases;
          } else if (tree.hasTag(SWITCH_EXPRESSION)) {
              ((JCSwitchExpression) tree).selector = selector;
              ((JCSwitchExpression) tree).cases = cases;
          } else {
              Assert.error();
          }
          if (enumSwitch) {
              result = visitEnumSwitch(tree, selector, cases);
          } else if (stringSwitch) {
              result = visitStringSwitch(tree, selector, cases);
          } else if (boxedSwitch) {
              //An switch over boxed primitive. Pattern matching switches are already translated
              //by TransPatterns, so all non-primitive types are only boxed primitives:
              result = visitBoxedPrimitiveSwitch(tree, selector, cases);
          } else {
              result = tree;
          }
      }
  
      public JCTree visitEnumSwitch(JCTree tree, JCExpression selector, List<JCCase> cases) {
          TypeSymbol enumSym = selector.type.tsym;
          EnumMapping map = mapForEnum(tree.pos(), enumSym);
          make_at(tree.pos());
          Symbol ordinalMethod = lookupMethod(tree.pos(),
                                              names.ordinal,
                                              selector.type,
                                              List.nil());
          JCExpression newSelector;
  
          if (cases.stream().anyMatch(c -> TreeInfo.isNull(c.labels.head))) {
              //for enum switches with case null, do:
              //switch ($selector != null ? $mapVar[$selector.ordinal()] : -1) {...}
              //replacing case null with case -1:
              VarSymbol dollar_s = new VarSymbol(FINAL|SYNTHETIC,
                                                 names.fromString("s" + tree.pos + this.target.syntheticNameChar()),
                                                 selector.type,
                                                 currentMethodSym);
              JCStatement var = make.at(tree.pos()).VarDef(dollar_s, selector).setType(dollar_s.type);
              newSelector = make.Indexed(map.mapVar,
                      make.App(make.Select(make.Ident(dollar_s),
                              ordinalMethod)));
              newSelector =
                      make.LetExpr(List.of(var),
                                   make.Conditional(makeBinary(NE, make.Ident(dollar_s), makeNull()),
                                                    newSelector,
                                                    makeLit(syms.intType, -1))
                                       .setType(newSelector.type))
                          .setType(newSelector.type);
          } else {
              newSelector = make.Indexed(map.mapVar,
                      make.App(make.Select(selector,
                              ordinalMethod)));
          }
          ListBuffer<JCCase> newCases = new ListBuffer<>();
          for (JCCase c : cases) {
              if (c.labels.head.isExpression()) {
                  JCExpression pat;
                  if (TreeInfo.isNull(c.labels.head)) {
                      pat = makeLit(syms.intType, -1);
                  } else {
                      VarSymbol label = (VarSymbol)TreeInfo.symbol((JCExpression) c.labels.head);
                      pat = map.forConstant(label);
                  }
                  newCases.append(make.Case(JCCase.STATEMENT, List.of(pat), c.stats, null));
              } else {
                  newCases.append(c);
              }
          }
          JCTree enumSwitch;
          if (tree.hasTag(SWITCH)) {
              enumSwitch = make.Switch(newSelector, newCases.toList());
          } else if (tree.hasTag(SWITCH_EXPRESSION)) {
              enumSwitch = make.SwitchExpression(newSelector, newCases.toList());
              enumSwitch.setType(tree.type);
          } else {
              Assert.error();
              throw new AssertionError();
          }
          patchTargets(enumSwitch, tree, enumSwitch);
          return enumSwitch;
      }
  
      public JCTree visitStringSwitch(JCTree tree, JCExpression selector, List<JCCase> caseList) {
          int alternatives = caseList.size();
  
          if (alternatives == 0) { // Strange but legal possibility (only legal for switch statement)
              return make.at(tree.pos()).Exec(attr.makeNullCheck(selector));
          } else {
              /*
               * The general approach used is to translate a single
               * string switch statement into a series of two chained
               * switch statements: the first a synthesized statement
               * switching on the argument string's hash value and
               * computing a string's position in the list of original
               * case labels, if any, followed by a second switch on the
               * computed integer value.  The second switch has the same
               * code structure as the original string switch statement
               * except that the string case labels are replaced with
               * positional integer constants starting at 0.
               *
               * The first switch statement can be thought of as an
               * inlined map from strings to their position in the case
               * label list.  An alternate implementation would use an
               * actual Map for this purpose, as done for enum switches.
               *
               * With some additional effort, it would be possible to
               * use a single switch statement on the hash code of the
               * argument, but care would need to be taken to preserve
               * the proper control flow in the presence of hash
               * collisions and other complications, such as
               * fallthroughs.  Switch statements with one or two
               * alternatives could also be specially translated into
               * if-then statements to omit the computation of the hash
               * code.
               *
               * The generated code assumes that the hashing algorithm
               * of String is the same in the compilation environment as
               * in the environment the code will run in.  The string
               * hashing algorithm in the SE JDK has been unchanged
               * since at least JDK 1.2.  Since the algorithm has been
               * specified since that release as well, it is very
               * unlikely to be changed in the future.
               *
               * Different hashing algorithms, such as the length of the
               * strings or a perfect hashing algorithm over the
               * particular set of case labels, could potentially be
               * used instead of String.hashCode.
               */
  
              ListBuffer<JCStatement> stmtList = new ListBuffer<>();
  
              // Map from String case labels to their original position in
              // the list of case labels.
              Map<String, Integer> caseLabelToPosition = new LinkedHashMap<>(alternatives + 1, 1.0f);
  
              // Map of hash codes to the string case labels having that hashCode.
              Map<Integer, Set<String>> hashToString = new LinkedHashMap<>(alternatives + 1, 1.0f);
  
              int casePosition = 0;
              JCCase nullCase = null;
              int nullCaseLabel = -1;
  
              for(JCCase oneCase : caseList) {
                  if (oneCase.labels.head.isExpression()) {
                      if (TreeInfo.isNull(oneCase.labels.head)) {
                          nullCase = oneCase;
                          nullCaseLabel = casePosition;
                      } else {
                          JCExpression expression = (JCExpression) oneCase.labels.head;
                          String labelExpr = (String) expression.type.constValue();
                          Integer mapping = caseLabelToPosition.put(labelExpr, casePosition);
                          Assert.checkNull(mapping);
                          int hashCode = labelExpr.hashCode();
  
                          Set<String> stringSet = hashToString.get(hashCode);
                          if (stringSet == null) {
                              stringSet = new LinkedHashSet<>(1, 1.0f);
                              stringSet.add(labelExpr);
                              hashToString.put(hashCode, stringSet);
                          } else {
                              boolean added = stringSet.add(labelExpr);
                              Assert.check(added);
                          }
                      }
                  }
                  casePosition++;
              }
  
              // Synthesize a switch statement that has the effect of
              // mapping from a string to the integer position of that
              // string in the list of case labels.  This is done by
              // switching on the hashCode of the string followed by an
              // if-then-else chain comparing the input for equality
              // with all the case labels having that hash value.
  
              /*
               * s$ = top of stack;
               * tmp$ = -1;
               * switch($s.hashCode()) {
               *     case caseLabel.hashCode:
               *         if (s$.equals("caseLabel_1")
               *           tmp$ = caseLabelToPosition("caseLabel_1");
               *         else if (s$.equals("caseLabel_2"))
               *           tmp$ = caseLabelToPosition("caseLabel_2");
               *         ...
               *         break;
               * ...
               * }
               */
  
              VarSymbol dollar_s = new VarSymbol(FINAL|SYNTHETIC,
                                                 names.fromString("s" + tree.pos + target.syntheticNameChar()),
                                                 syms.stringType,
                                                 currentMethodSym);
              stmtList.append(make.at(tree.pos()).VarDef(dollar_s, selector).setType(dollar_s.type));
  
              VarSymbol dollar_tmp = new VarSymbol(SYNTHETIC,
                                                   names.fromString("tmp" + tree.pos + target.syntheticNameChar()),
                                                   syms.intType,
                                                   currentMethodSym);
              JCVariableDecl dollar_tmp_def =
                  (JCVariableDecl)make.VarDef(dollar_tmp, make.Literal(INT, -1)).setType(dollar_tmp.type);
              dollar_tmp_def.init.type = dollar_tmp.type = syms.intType;
              stmtList.append(dollar_tmp_def);
              ListBuffer<JCCase> caseBuffer = new ListBuffer<>();
              // hashCode will trigger nullcheck on original switch expression
              JCMethodInvocation hashCodeCall = makeCall(make.Ident(dollar_s),
                                                         names.hashCode,
                                                         List.nil()).setType(syms.intType);
              JCSwitch switch1 = make.Switch(hashCodeCall,
                                          caseBuffer.toList());
              for(Map.Entry<Integer, Set<String>> entry : hashToString.entrySet()) {
                  int hashCode = entry.getKey();
                  Set<String> stringsWithHashCode = entry.getValue();
                  Assert.check(stringsWithHashCode.size() >= 1);
  
                  JCStatement elsepart = null;
                  for(String caseLabel : stringsWithHashCode ) {
                      JCMethodInvocation stringEqualsCall = makeCall(make.Ident(dollar_s),
                                                                     names.equals,
                                                                     List.of(make.Literal(caseLabel)));
                      elsepart = make.If(stringEqualsCall,
                                         make.Exec(make.Assign(make.Ident(dollar_tmp),
                                                               make.Literal(caseLabelToPosition.get(caseLabel))).
                                                   setType(dollar_tmp.type)),
                                         elsepart);
                  }
  
                  ListBuffer<JCStatement> lb = new ListBuffer<>();
                  JCBreak breakStmt = make.Break(null);
                  breakStmt.target = switch1;
                  lb.append(elsepart).append(breakStmt);
  
                  caseBuffer.append(make.Case(JCCase.STATEMENT, List.of(make.Literal(hashCode)), lb.toList(), null));
              }
  
              switch1.cases = caseBuffer.toList();
  
              if (nullCase != null) {
                  stmtList.append(make.If(makeBinary(NE, make.Ident(dollar_s), makeNull()), switch1, make.Exec(make.Assign(make.Ident(dollar_tmp),
                                                               make.Literal(nullCaseLabel)).
                                                   setType(dollar_tmp.type))).setType(syms.intType));
              } else {
                  stmtList.append(switch1);
              }
  
              // Make isomorphic switch tree replacing string labels
              // with corresponding integer ones from the label to
              // position map.
  
              ListBuffer<JCCase> lb = new ListBuffer<>();
              for(JCCase oneCase : caseList ) {
                  boolean isDefault = !oneCase.labels.head.isExpression();
                  JCCaseLabel caseExpr;
                  if (isDefault)
                      caseExpr = null;
                  else if (oneCase == nullCase) {
                      caseExpr = make.Literal(nullCaseLabel);
                  } else {
                      caseExpr = make.Literal(caseLabelToPosition.get((String)TreeInfo.skipParens((JCExpression) oneCase.labels.head).
                                                                      type.constValue()));
                  }
  
                  lb.append(make.Case(JCCase.STATEMENT, caseExpr == null ? List.of(make.DefaultCaseLabel()) : List.of(caseExpr),
                                      oneCase.stats, null));
              }
  
              if (tree.hasTag(SWITCH)) {
                  JCSwitch switch2 = make.Switch(make.Ident(dollar_tmp), lb.toList());
                  // Rewire up old unlabeled break statements to the
                  // replacement switch being created.
                  patchTargets(switch2, tree, switch2);
  
                  stmtList.append(switch2);
  
                  JCBlock res = make.Block(0L, stmtList.toList());
                  res.endpos = TreeInfo.endPos(tree);
                  return res;
              } else {
                  JCSwitchExpression switch2 = make.SwitchExpression(make.Ident(dollar_tmp), lb.toList());
  
                  // Rewire up old unlabeled break statements to the
                  // replacement switch being created.
                  patchTargets(switch2, tree, switch2);
  
                  switch2.setType(tree.type);
  
                  LetExpr res = make.LetExpr(stmtList.toList(), switch2);
  
                  res.needsCond = true;
                  res.setType(tree.type);
  
                  return res;
              }
          }
      }
  
      private JCTree visitBoxedPrimitiveSwitch(JCTree tree, JCExpression selector, List<JCCase> cases) {
          JCExpression newSelector;
  
          if (cases.stream().anyMatch(c -> TreeInfo.isNull(c.labels.head))) {
              //a switch over a boxed primitive, with a null case. Pick two constants that are
              //not used by any branch in the case (c1 and c2), close to other constants that are
              //used in the switch. Then do:
              //switch ($selector != null ? $selector != c1 ? $selector : c2 : c1) {...}
              //replacing case null with case c1
              Set<Integer> constants = new LinkedHashSet<>();
              JCCase nullCase = null;
  
              for (JCCase c : cases) {
                  if (TreeInfo.isNull(c.labels.head)) {
                      nullCase = c;
                  } else if (!c.labels.head.hasTag(DEFAULTCASELABEL)) {
                      constants.add((int) c.labels.head.type.constValue());
                  }
              }
  
              Assert.checkNonNull(nullCase);
  
              int nullValue = constants.isEmpty() ? 0 : constants.iterator().next();
  
              while (constants.contains(nullValue)) nullValue++;
  
              constants.add(nullValue);
              nullCase.labels.head = makeLit(syms.intType, nullValue);
  
              int replacementValue = nullValue;
  
              while (constants.contains(replacementValue)) replacementValue++;
  
              VarSymbol dollar_s = new VarSymbol(FINAL|SYNTHETIC,
                                                 names.fromString("s" + tree.pos + this.target.syntheticNameChar()),
                                                 selector.type,
                                                 currentMethodSym);
              JCStatement var = make.at(tree.pos()).VarDef(dollar_s, selector).setType(dollar_s.type);
              JCExpression nullValueReplacement =
                      make.Conditional(makeBinary(NE,
                                                   unbox(make.Ident(dollar_s), syms.intType),
                                                   makeLit(syms.intType, nullValue)),
                                       unbox(make.Ident(dollar_s), syms.intType),
                                       makeLit(syms.intType, replacementValue))
                          .setType(syms.intType);
              JCExpression nullCheck =
                      make.Conditional(makeBinary(NE, make.Ident(dollar_s), makeNull()),
                                       nullValueReplacement,
                                       makeLit(syms.intType, nullValue))
                          .setType(syms.intType);
              newSelector = make.LetExpr(List.of(var), nullCheck).setType(syms.intType);
          } else {
              newSelector = unbox(selector, syms.intType);
          }
  
          if (tree.hasTag(SWITCH)) {
              ((JCSwitch) tree).selector = newSelector;
          } else {
              ((JCSwitchExpression) tree).selector = newSelector;
          }
  
          return tree;
      }
  
      @Override
      public void visitBreak(JCBreak tree) {
          result = tree;
      }
  
      @Override
      public void visitYield(JCYield tree) {
          tree.value = translate(tree.value, tree.target.type);
          result = tree;
      }
  
      public void visitNewArray(JCNewArray tree) {
          tree.elemtype = translate(tree.elemtype);
          for (List<JCExpression> t = tree.dims; t.tail != null; t = t.tail)
              if (t.head != null) t.head = translate(t.head, syms.intType);
          tree.elems = translate(tree.elems, types.elemtype(tree.type));
          result = tree;
      }
  
      public void visitSelect(JCFieldAccess tree) {
          // need to special case-access of the form C.super.x
          // these will always need an access method, unless C
          // is a default interface subclassed by the current class.
          boolean qualifiedSuperAccess =
              tree.selected.hasTag(SELECT) &&
              TreeInfo.name(tree.selected) == names._super &&
              !types.isDirectSuperInterface(((JCFieldAccess)tree.selected).selected.type.tsym, currentClass);
          tree.selected = translate(tree.selected);
          if (tree.name == names._class) {
              result = classOf(tree.selected);
          }
          else if (tree.name == names._super &&
                  types.isDirectSuperInterface(tree.selected.type.tsym, currentClass)) {
              //default super call!! Not a classic qualified super call
              TypeSymbol supSym = tree.selected.type.tsym;
              Assert.checkNonNull(types.asSuper(currentClass.type, supSym));
              result = tree;
          }
          else if (tree.name == names._this || tree.name == names._super) {
              result = makeThis(tree.pos(), tree.selected.type.tsym);
          }
          else
              result = access(tree.sym, tree, enclOp, qualifiedSuperAccess);
      }
  
      public void visitLetExpr(LetExpr tree) {
          tree.defs = translate(tree.defs);
          tree.expr = translate(tree.expr, tree.type);
          result = tree;
      }
  
      // There ought to be nothing to rewrite here;
      // we don't generate code.
      public void visitAnnotation(JCAnnotation tree) {
          result = tree;
      }
  
      @Override
      public void visitTry(JCTry tree) {
          if (tree.resources.nonEmpty()) {
              result = makeTwrTry(tree);
              return;
          }
  
          boolean hasBody = tree.body.getStatements().nonEmpty();
          boolean hasCatchers = tree.catchers.nonEmpty();
          boolean hasFinally = tree.finalizer != null &&
                  tree.finalizer.getStatements().nonEmpty();
  
          if (!hasCatchers && !hasFinally) {
              result = translate(tree.body);
              return;
          }
  
          if (!hasBody) {
              if (hasFinally) {
                  result = translate(tree.finalizer);
              } else {
                  result = translate(tree.body);
              }
              return;
          }
  
          // no optimizations possible
          super.visitTry(tree);
      }
  
  /**************************************************************************
   * main method
   *************************************************************************/
  
      /** Translate a toplevel class and return a list consisting of
       *  the translated class and translated versions of all inner classes.
       *  @param env   The attribution environment current at the class definition.
       *               We need this for resolving some additional symbols.
       *  @param cdef  The tree representing the class definition.
       */
      public List<JCTree> translateTopLevelClass(Env<AttrContext> env, JCTree cdef, TreeMaker make) {
          ListBuffer<JCTree> translated = null;
          try {
              attrEnv = env;
              this.make = make;
              endPosTable = env.toplevel.endPositions;
              currentClass = null;
              currentMethodDef = null;
              outermostClassDef = (cdef.hasTag(CLASSDEF)) ? (JCClassDecl)cdef : null;
              outermostMemberDef = null;
              this.translated = new ListBuffer<>();
              classdefs = new HashMap<>();
              actualSymbols = new HashMap<>();
              freevarCache = new HashMap<>();
              proxies = new HashMap<>();
              twrVars = WriteableScope.create(syms.noSymbol);
              outerThisStack = List.nil();
              accessNums = new HashMap<>();
              accessSyms = new HashMap<>();
              accessConstrs = new HashMap<>();
              accessConstrTags = List.nil();
              accessed = new ListBuffer<>();
              translate(cdef, (JCExpression)null);
              for (List<Symbol> l = accessed.toList(); l.nonEmpty(); l = l.tail)
                  makeAccessible(l.head);
              for (EnumMapping map : enumSwitchMap.values())
                  map.translate();
              checkConflicts(this.translated.toList());
              checkAccessConstructorTags();
              translated = this.translated;
          } finally {
              // note that recursive invocations of this method fail hard
              attrEnv = null;
              this.make = null;
              endPosTable = null;
              currentClass = null;
              currentMethodDef = null;
              outermostClassDef = null;
              outermostMemberDef = null;
              this.translated = null;
              classdefs = null;
              actualSymbols = null;
              freevarCache = null;
              proxies = null;
              outerThisStack = null;
              accessNums = null;
              accessSyms = null;
              accessConstrs = null;
              accessConstrTags = null;
              accessed = null;
              enumSwitchMap.clear();
              assertionsDisabledClassCache = null;
          }
          return translated.toList();
      }
  }
  