/*
 * Copyright (c) 1999, 2019, 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 com.sun.tools.javac.comp;

import java.util.*;
import java.util.stream.Collectors;

import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Kinds.KindSelector;
import com.sun.tools.javac.code.Scope.WriteableScope;
import com.sun.tools.javac.jvm.*;
import com.sun.tools.javac.jvm.PoolConstant.LoadableConstant;
import com.sun.tools.javac.main.Option.PkgInfo;
import com.sun.tools.javac.resources.CompilerProperties.Fragments;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.List;

import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.code.Symbol.OperatorSymbol.AccessCode;
import com.sun.tools.javac.resources.CompilerProperties.Errors;
import com.sun.tools.javac.tree.JCTree.*;
import com.sun.tools.javac.code.Type.*;

import com.sun.tools.javac.jvm.Target;
import com.sun.tools.javac.tree.EndPosTable;

import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Flags.BLOCK;
import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
import static com.sun.tools.javac.code.TypeTag.*;
import static com.sun.tools.javac.code.Kinds.Kind.*;
import static com.sun.tools.javac.jvm.ByteCodes.*;
import com.sun.tools.javac.tree.JCTree.JCBreak;
import com.sun.tools.javac.tree.JCTree.JCCase;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import com.sun.tools.javac.tree.JCTree.JCExpressionStatement;
import static com.sun.tools.javac.tree.JCTree.JCOperatorExpression.OperandPos.LEFT;
import com.sun.tools.javac.tree.JCTree.JCSwitchExpression;
import static com.sun.tools.javac.tree.JCTree.Tag.*;

This pass translates away some syntactic sugar: inner classes,
 class literals, assertions, foreach loops, etc.
 
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.
/** 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 Source source;
    private final TypeEnvs typeEnvs;
    private final Name dollarAssertionsDisabled;
    private final Name classDollar;
    private final Name dollarCloseResource;
    private final Types types;
    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);
        source = Source.instance(context);
        typeEnvs = TypeEnvs.instance(context);
        dollarAssertionsDisabled = names.
            fromString(target.syntheticNameChar() + "assertionsDisabled");
        classDollar = names.
            fromString("class" + target.syntheticNameChar());
        dollarCloseResource = names.
            fromString(target.syntheticNameChar() + "closeResource");

        types = Types.instance(context);
        Options options = Options.instance(context);
        debugLower = options.isSet("debuglower");
        pkginfoOpt = PkgInfo.get(options);
        disableProtectedAccessors = options.isSet("disableProtectedAccessors");
    }

    
The currently enclosing class.
/** The currently enclosing class.
     */
    ClassSymbol currentClass;

    
A queue of all translated classes.
/** A queue of all translated classes.
     */
    ListBuffer<JCTree> translated;

    
Environment for symbol lookup, set by translateTopLevelClass.
/** Environment for symbol lookup, set by translateTopLevelClass.
     */
    Env<AttrContext> attrEnv;

    
A hash table mapping syntax trees to their ending source positions.
/** A hash table mapping syntax trees to their ending source positions.
     */
    EndPosTable endPosTable;

/**************************************************************************
 * Global mappings
 *************************************************************************/

    
A hash table mapping local classes to their definitions.
/** 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.
/** 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.
/** 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.
/** The current method definition.
     */
    JCMethodDecl currentMethodDef;

    
The current method symbol.
/** The current method symbol.
     */
    MethodSymbol currentMethodSym;

    
The currently enclosing outermost class definition.
/** The currently enclosing outermost class definition.
     */
    JCClassDecl outermostClassDef;

    
The currently enclosing outermost member definition.
/** 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).
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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 BasicFreeVarCollector. /**
     * Lower-specific subclass of {@code BasicFreeVarCollector}.
     */
    class FreeVarCollector extends BasicFreeVarCollector {

        
The owner of the local class.
/** The owner of the local class.
         */
        Symbol owner;

        
The local class.
/** The local class.
         */
        ClassSymbol clazz;

        
The list of owner's variables accessed from within the local class,
 without any duplicates.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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);
                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.isLocal()) {
            return null;
        }
        Symbol currentOwner = c.owner;
        while (currentOwner.owner.kind.matches(KindSelector.TYP) && currentOwner.isLocal()) {
            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).
/** 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.
 
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:
 
we translate
 
         switch(colorExpression) {
         case red: stmt1;
         case green: stmt2;
         }
 
 into
 
         switch(Outer$0.$EnumMap$Color[colorExpression.ordinal()]) {
         case 1: stmt1;
         case 2: stmt2
         }
 
 with the auxiliary table initialized as follows:
 
         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) {}
             }
         }
 
 class EnumMapping provides mapping data and support methods for this translation.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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..
/** 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
/** 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.
        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.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.
/** 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 '$' chars at the end of the name until no match
 is found.
Params:
name – base name
s – scope in which the name has to be unique
Returns:
fresh synthetic name/** Create a fresh synthetic name within a given scope - the unique name is
     *  obtained by appending '$' 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
/** 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.
/** 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.
/** 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.
/** 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 synthethise 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.
/** Anon inner classes are used as access constructor tags.
     * accessConstructorTag will use an existing anon class if one is available,
     * and synthethise 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;
            // Create class definition tree.
            JCClassDecl cdec = makeEmptyClass(STATIC | SYNTHETIC,
                    c.outermostClass(), c.flatname, false);
            swapAccessConstructorTag(c, cdec.sym);
            translated.append(cdec);
        }
    }
    // where
    private boolean isTranslatedClassAvailable(ClassSymbol c) {
        for (JCTree tree: translated) {
            if (tree.hasTag(CLASSDEF)
                    && ((JCClassDecl) tree).sym == c) {
                return true;
            }
        }
        return false;
    }

    void swapAccessConstructorTag(ClassSymbol oldCTag, ClassSymbol newCTag) {
        for (MethodSymbol methodSymbol : accessConstrs.values()) {
            Assert.check(methodSymbol.type.hasTag(METHOD));
            MethodType oldMethodType =
                    (MethodType)methodSymbol.type;
            if (oldMethodType.argtypes.head.tsym == oldCTag)
                methodSymbol.type =
                    types.createMethodTypeWithParameters(oldMethodType,
                        oldMethodType.getParameterTypes().tail
                            .prepend(newCTag.erasure(types)));
        }
    }

/**************************************************************************
 * Access methods
 *************************************************************************/

    
A mapping from symbols to their access numbers.
/** 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.
/** 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.
/** 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.
/** A list of all class symbols used for access constructor tags.
     */
    private List<ClassSymbol> accessConstrTags;

    
A queue for all accessed symbols.
/** 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.
/** 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.
/** 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.
/** 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'.
/** 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?
/** 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.
/** 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?
/** 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.isLocal()) {
            // 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?
/** 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?
/** 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?
/** 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);
                Assert.check(sym != null && (sym.flags_field & FINAL) != 0);
                tree = make.at(tree.pos).Ident(sym);
            }
        }
        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);
                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.
/** 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.
/** 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.
/** 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)
                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.
/** 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);
        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.
/** 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 refered
                //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.
/** 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.
/** 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
/** 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.
/** 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.
/** 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.
/** 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
/** 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$n field.
 @param pos        The source code position of the definition.
 @param owner      The method in which the definition goes.
/** Definition for this$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$n field.
 @param pos        The source code position of the definition.
 @param owner      The class in which the definition goes.
/** Definition for this$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.
/** 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 C.this. @param pos The source code position to be used for the tree. @param c The qualifier class. /** 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;
  }
}
Params:
tree –  The try statement to inspect.
Returns:
A a desugared try-with-resources tree, or the original
try block if there are no resources to manage./**
     * 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 C.this. Never pick the current `this'. @param pos The source code position to be used for the tree. @param c The qualifier class. /** 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));
            Assert.error();
            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));
                    Assert.error(); // should have been caught in Attr
                    return tree;
                }
                ot = ots.head;
            } while (ot.owner != otc);
            if (otc.owner.kind != PCK && !otc.hasOuterInstance()) {
                chk.earlyRefError(pos, c);
                Assert.error(); // should have been caught in Attr
                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 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? /** 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".
/**
     * 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));
            Assert.error();
            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));
                    Assert.error();
                    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 this.name = name, where name is the name of a free variable. /** 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 this.this$n = this$n. /** 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
 $assertionsDisabled flag.  We create an anonymous nested class
 (unless one already exists) and return its symbol.  However,
 for backward compatibility in 1.4 and earlier we use the
 top-level class itself.
/** Return the symbol of a class to contain a cache of
     *  compiler-generated statics such as class$ 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(). /** 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.
/** 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.
/**************************************************************************
 * Code for enabling/disabling assertions.
 *************************************************************************/

    private ClassSymbol assertionsDisabledClassCache;

    
Used to create an auxiliary class to hold $assertionsDisabled for interfaces.
/**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
/**************************************************************************
 * 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
 
   (let TYPE TEMP = RVAL;
    in (BUILDER(TEMP)))
 
 where TEMP is a newly declared variable
 in the let expression.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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.
/** 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
        if ((tree.mods.flags & ENUM) != 0 &&
            (types.supertype(currentClass.type).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.isLocal()) {
            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) {
        return tree.sym.getRecordComponents().stream()
                .filter(rc -> (rc.accessor.flags() & Flags.GENERATED_MEMBER) != 0)
                .map(rc -> {
                    make_at(tree.pos());
                    return make.MethodDef(rc.accessor, make.Block(0,
                            List.of(make.Return(make.Ident(rc)))));
                }).collect(List.collector());
    }

    
Translate an enum class. /** 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);
            }
        }

        // private static final T[] #VALUES = { a, b, c };
        Name valuesName = names.fromString(target.syntheticNameChar() + "VALUES");
        while (tree.sym.members().findFirst(valuesName) != null) // avoid name clash
            valuesName = names.fromString(valuesName + "" + target.syntheticNameChar());
        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;
        enumDefs.append(make.VarDef(valuesVar, newArray));
        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 = names.fromString(target.syntheticNameChar() + "result");
            while (tree.sym.members().findFirst(resultName) != null) // avoid name clash
                resultName = names.fromString(resultName + "" + target.syntheticNameChar());
            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;
            }
        }

    
Translate an enumeration constant and its initializer. /** Translate an enumeration constant and its initializer. */
    private void visitEnumConstantDef(JCVariableDecl var, int ordinal) {
        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. /** 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
/**
     * Signature Generation
     */
    private class LowerSignatureGenerator extends Types.SignatureGenerator {

        
An output buffer for type signatures.
/**
         * 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
Params:
site –                the site
tree –                a class declaration tree
msym –                the method symbol
staticArgTypes –      the static argument types
staticArgValues –     the static argument values
bootstrapName –       the bootstrap name to look for
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
isStatic –            is it static or not
Returns:
                   a field access tree/**
     * 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.isLocal())) {
            // 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);
            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.isLocal()) {
            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.isLocal()) {
                // 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) {
            translate(tree.def);
            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.
/** 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.
/** 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.
/** 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.isLocal()) {
                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
                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.isLocal() || 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()) {
            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. /** Expand a boxing or unboxing conversion if needed. */
    @SuppressWarnings("unchecked") // XXX unchecked
    <T extends JCExpression> T boxIfNeeded(T tree, Type type) {
        boolean havePrimitive = tree.type.isPrimitive();
        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. /** Box up a single primitive expression. */
    JCExpression boxPrimitive(JCExpression tree) {
        return boxPrimitive(tree, types.boxedClass(tree.type).type);
    }

    
Box up a single primitive expression. /** 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. /** Unbox an object to a primitive value. */
    JCExpression unbox(JCExpression tree, Type primitive) {
        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);
        }
        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.
/** 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.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 /** 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.  /** 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
    for ( T v : arrayexpr ) stmt;

(where arrayexpr is of an array type) gets translated to

    for ( { arraytype #arr = arrayexpr;
            int #len = array.length;
            int #i = 0; };
          #i < #len; i$++ ) {
        T v = arr$[#i];
        stmt;
    }

where #arr, #len, and #i are freshly named synthetic local variables.
/**
         * 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. /** 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
    for ( T v : coll ) stmt ;
 (where coll implements Iterable<? extends T>) gets translated to 

    for ( Iterator<? extends T> #i = coll.iterator(); #i.hasNext(); ) {
        T v = (T) #i.next();
        stmt;
    }

where #i is a freshly named synthetic local variable.
/**
         * 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.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) {
        handleSwitch(tree, tree.selector, tree.cases);
    }

    @Override
    public void visitSwitchExpression(JCSwitchExpression tree) {
        if (tree.cases.stream().noneMatch(c -> c.pats.isEmpty())) {
            JCThrow thr = make.Throw(makeNewClass(syms.incompatibleClassChangeErrorType,
                                                  List.nil()));
            JCCase c = make.Case(JCCase.STATEMENT, List.nil(), List.of(thr), null);
            tree.cases = tree.cases.append(c);
        }
        handleSwitch(tree, tree.selector, tree.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.pats.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<JCExpression> patterns = c.pats;
                    while (patterns.tail.nonEmpty()) {
                        convertedCases.append(make_at(c.pos()).Case(JCCase.STATEMENT,
                                                           List.of(patterns.head),
                                                           List.nil(),
                                                           null));
                        patterns = patterns.tail;
                    }
                    c.pats = patterns;
                    convertedCases.append(c);
                    break;
            }
        }

        for (JCCase c : convertedCases) {
            if (c.caseKind == JCCase.RULE && c.completesNormally) {
                JCBreak b = make_at(c.pos()).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);
        Type target = enumSwitch ? selector.type :
            (stringSwitch? syms.stringType : syms.intType);
        selector = translate(selector, target);
        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 {
            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());
        JCArrayAccess newSelector = make.Indexed(map.mapVar,
                                        make.App(make.Select(selector,
                                                             ordinalMethod)));
        ListBuffer<JCCase> newCases = new ListBuffer<>();
        for (JCCase c : cases) {
            if (c.pats.nonEmpty()) {
                VarSymbol label = (VarSymbol)TreeInfo.symbol(c.pats.head);
                JCLiteral 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;

            for(JCCase oneCase : caseList) {
                if (oneCase.pats.nonEmpty()) { // pats is empty for a "default" case
                    JCExpression expression = oneCase.pats.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();
            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.pats.isEmpty());
                JCExpression caseExpr;
                if (isDefault)
                    caseExpr = null;
                else {
                    caseExpr = make.Literal(caseLabelToPosition.get((String)TreeInfo.skipParens(oneCase.pats.head).
                                                                    type.constValue()));
                }

                lb.append(make.Case(JCCase.STATEMENT, caseExpr == null ? List.nil() : 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);

                return make.Block(0L, stmtList.toList());
            } 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;
            }
        }
    }

    @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.
/** 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();
    }
}