Symtab.java revision 2824:e0b35c562008 
1/*
2 * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.tools.javac.code;
27
28import java.util.HashMap;
29import java.util.HashSet;
30import java.util.Map;
31import java.util.Set;
32
33import javax.lang.model.element.ElementVisitor;
34import javax.tools.JavaFileObject;
35
36
37import com.sun.tools.javac.code.Scope.WriteableScope;
38import com.sun.tools.javac.code.Symbol.ClassSymbol;
39import com.sun.tools.javac.code.Symbol.Completer;
40import com.sun.tools.javac.code.Symbol.CompletionFailure;
41import com.sun.tools.javac.code.Symbol.MethodSymbol;
42import com.sun.tools.javac.code.Symbol.OperatorSymbol;
43import com.sun.tools.javac.code.Symbol.PackageSymbol;
44import com.sun.tools.javac.code.Symbol.TypeSymbol;
45import com.sun.tools.javac.code.Symbol.VarSymbol;
46import com.sun.tools.javac.code.Type.BottomType;
47import com.sun.tools.javac.code.Type.ClassType;
48import com.sun.tools.javac.code.Type.ErrorType;
49import com.sun.tools.javac.code.Type.JCPrimitiveType;
50import com.sun.tools.javac.code.Type.JCVoidType;
51import com.sun.tools.javac.code.Type.MethodType;
52import com.sun.tools.javac.code.Type.UnknownType;
53import com.sun.tools.javac.jvm.ByteCodes;
54import com.sun.tools.javac.jvm.Target;
55import com.sun.tools.javac.util.Assert;
56import com.sun.tools.javac.util.Context;
57import com.sun.tools.javac.util.Convert;
58import com.sun.tools.javac.util.DefinedBy;
59import com.sun.tools.javac.util.DefinedBy.Api;
60import com.sun.tools.javac.util.JavacMessages;
61import com.sun.tools.javac.util.List;
62import com.sun.tools.javac.util.Log;
63import com.sun.tools.javac.util.Name;
64import com.sun.tools.javac.util.Names;
65
66import static com.sun.tools.javac.code.Flags.*;
67import static com.sun.tools.javac.code.Kinds.Kind.*;
68import static com.sun.tools.javac.jvm.ByteCodes.*;
69import static com.sun.tools.javac.code.TypeTag.*;
70
71/** A class that defines all predefined constants and operators
72 *  as well as special classes such as java.lang.Object, which need
73 *  to be known to the compiler. All symbols are held in instance
74 *  fields. This makes it possible to work in multiple concurrent
75 *  projects, which might use different class files for library classes.
76 *
77 *  <p><b>This is NOT part of any supported API.
78 *  If you write code that depends on this, you do so at your own risk.
79 *  This code and its internal interfaces are subject to change or
80 *  deletion without notice.</b>
81 */
82public class Symtab {
83    /** The context key for the symbol table. */
84    protected static final Context.Key<Symtab> symtabKey = new Context.Key<>();
85
86    /** Get the symbol table instance. */
87    public static Symtab instance(Context context) {
88        Symtab instance = context.get(symtabKey);
89        if (instance == null)
90            instance = new Symtab(context);
91        return instance;
92    }
93
94    /** Builtin types.
95     */
96    public final JCPrimitiveType byteType = new JCPrimitiveType(BYTE, null);
97    public final JCPrimitiveType charType = new JCPrimitiveType(CHAR, null);
98    public final JCPrimitiveType shortType = new JCPrimitiveType(SHORT, null);
99    public final JCPrimitiveType intType = new JCPrimitiveType(INT, null);
100    public final JCPrimitiveType longType = new JCPrimitiveType(LONG, null);
101    public final JCPrimitiveType floatType = new JCPrimitiveType(FLOAT, null);
102    public final JCPrimitiveType doubleType = new JCPrimitiveType(DOUBLE, null);
103    public final JCPrimitiveType booleanType = new JCPrimitiveType(BOOLEAN, null);
104    public final Type botType = new BottomType();
105    public final JCVoidType voidType = new JCVoidType();
106
107    private final Names names;
108    private final Completer initialCompleter;
109    private final Target target;
110
111    /** A symbol for the root package.
112     */
113    public final PackageSymbol rootPackage;
114
115    /** A symbol for the unnamed package.
116     */
117    public final PackageSymbol unnamedPackage;
118
119    /** A symbol that stands for a missing symbol.
120     */
121    public final TypeSymbol noSymbol;
122
123    /** The error symbol.
124     */
125    public final ClassSymbol errSymbol;
126
127    /** The unknown symbol.
128     */
129    public final ClassSymbol unknownSymbol;
130
131    /** A value for the errType, with a originalType of noType */
132    public final Type errType;
133
134    /** A value for the unknown type. */
135    public final Type unknownType;
136
137    /** The builtin type of all arrays. */
138    public final ClassSymbol arrayClass;
139    public final MethodSymbol arrayCloneMethod;
140
141    /** VGJ: The (singleton) type of all bound types. */
142    public final ClassSymbol boundClass;
143
144    /** The builtin type of all methods. */
145    public final ClassSymbol methodClass;
146
147    /** Predefined types.
148     */
149    public final Type objectType;
150    public final Type classType;
151    public final Type classLoaderType;
152    public final Type stringType;
153    public final Type stringBufferType;
154    public final Type stringBuilderType;
155    public final Type cloneableType;
156    public final Type serializableType;
157    public final Type serializedLambdaType;
158    public final Type methodHandleType;
159    public final Type methodHandleLookupType;
160    public final Type methodTypeType;
161    public final Type nativeHeaderType;
162    public final Type throwableType;
163    public final Type errorType;
164    public final Type interruptedExceptionType;
165    public final Type illegalArgumentExceptionType;
166    public final Type exceptionType;
167    public final Type runtimeExceptionType;
168    public final Type classNotFoundExceptionType;
169    public final Type noClassDefFoundErrorType;
170    public final Type noSuchFieldErrorType;
171    public final Type assertionErrorType;
172    public final Type cloneNotSupportedExceptionType;
173    public final Type annotationType;
174    public final TypeSymbol enumSym;
175    public final Type listType;
176    public final Type collectionsType;
177    public final Type comparableType;
178    public final Type comparatorType;
179    public final Type arraysType;
180    public final Type iterableType;
181    public final Type iteratorType;
182    public final Type annotationTargetType;
183    public final Type overrideType;
184    public final Type retentionType;
185    public final Type deprecatedType;
186    public final Type suppressWarningsType;
187    public final Type inheritedType;
188    public final Type profileType;
189    public final Type proprietaryType;
190    public final Type systemType;
191    public final Type autoCloseableType;
192    public final Type trustMeType;
193    public final Type lambdaMetafactory;
194    public final Type repeatableType;
195    public final Type documentedType;
196    public final Type elementTypeType;
197    public final Type functionalInterfaceType;
198
199    /** The symbol representing the length field of an array.
200     */
201    public final VarSymbol lengthVar;
202
203    /** The symbol representing the final finalize method on enums */
204    public final MethodSymbol enumFinalFinalize;
205
206    /** The symbol representing the close method on TWR AutoCloseable type */
207    public final MethodSymbol autoCloseableClose;
208
209    /** The predefined type that belongs to a tag.
210     */
211    public final Type[] typeOfTag = new Type[TypeTag.getTypeTagCount()];
212
213    /** The name of the class that belongs to a basix type tag.
214     */
215    public final Name[] boxedName = new Name[TypeTag.getTypeTagCount()];
216
217    /** A hashtable containing the encountered top-level and member classes,
218     *  indexed by flat names. The table does not contain local classes.
219     *  It should be updated from the outside to reflect classes defined
220     *  by compiled source files.
221     */
222    public final Map<Name, ClassSymbol> classes = new HashMap<>();
223
224    /** A hashtable containing the encountered packages.
225     *  the table should be updated from outside to reflect packages defined
226     *  by compiled source files.
227     */
228    public final Map<Name, PackageSymbol> packages = new HashMap<>();
229
230    public void initType(Type type, ClassSymbol c) {
231        type.tsym = c;
232        typeOfTag[type.getTag().ordinal()] = type;
233    }
234
235    public void initType(Type type, String name) {
236        initType(
237            type,
238            new ClassSymbol(
239                PUBLIC, names.fromString(name), type, rootPackage));
240    }
241
242    public void initType(Type type, String name, String bname) {
243        initType(type, name);
244            boxedName[type.getTag().ordinal()] = names.fromString("java.lang." + bname);
245    }
246
247    /** The class symbol that owns all predefined symbols.
248     */
249    public final ClassSymbol predefClass;
250
251    /** Enter a class into symbol table.
252     *  @param s The name of the class.
253     */
254    private Type enterClass(String s) {
255        return enterClass(names.fromString(s)).type;
256    }
257
258    public void synthesizeEmptyInterfaceIfMissing(final Type type) {
259        final Completer completer = type.tsym.completer;
260        if (completer != null) {
261            type.tsym.completer = new Completer() {
262                public void complete(Symbol sym) throws CompletionFailure {
263                    try {
264                        completer.complete(sym);
265                    } catch (CompletionFailure e) {
266                        sym.flags_field |= (PUBLIC | INTERFACE);
267                        ((ClassType) sym.type).supertype_field = objectType;
268                    }
269                }
270            };
271        }
272    }
273
274    public void synthesizeBoxTypeIfMissing(final Type type) {
275        ClassSymbol sym = enterClass(boxedName[type.getTag().ordinal()]);
276        final Completer completer = sym.completer;
277        if (completer != null) {
278            sym.completer = new Completer() {
279                public void complete(Symbol sym) throws CompletionFailure {
280                    try {
281                        completer.complete(sym);
282                    } catch (CompletionFailure e) {
283                        sym.flags_field |= PUBLIC;
284                        ((ClassType) sym.type).supertype_field = objectType;
285                        MethodSymbol boxMethod =
286                            new MethodSymbol(PUBLIC | STATIC, names.valueOf,
287                                             new MethodType(List.of(type), sym.type,
288                                    List.<Type>nil(), methodClass),
289                                sym);
290                        sym.members().enter(boxMethod);
291                        MethodSymbol unboxMethod =
292                            new MethodSymbol(PUBLIC,
293                                type.tsym.name.append(names.Value), // x.intValue()
294                                new MethodType(List.<Type>nil(), type,
295                                    List.<Type>nil(), methodClass),
296                                sym);
297                        sym.members().enter(unboxMethod);
298                    }
299                }
300            };
301        }
302
303    }
304
305    // Enter a synthetic class that is used to mark classes in ct.sym.
306    // This class does not have a class file.
307    private Type enterSyntheticAnnotation(String name) {
308        ClassType type = (ClassType)enterClass(name);
309        ClassSymbol sym = (ClassSymbol)type.tsym;
310        sym.completer = null;
311        sym.flags_field = PUBLIC|ACYCLIC|ANNOTATION|INTERFACE;
312        sym.erasure_field = type;
313        sym.members_field = WriteableScope.create(sym);
314        type.typarams_field = List.nil();
315        type.allparams_field = List.nil();
316        type.supertype_field = annotationType;
317        type.interfaces_field = List.nil();
318        return type;
319    }
320
321    /** Constructor; enters all predefined identifiers and operators
322     *  into symbol table.
323     */
324    protected Symtab(Context context) throws CompletionFailure {
325        context.put(symtabKey, this);
326
327        names = Names.instance(context);
328        target = Target.instance(context);
329
330        // Create the unknown type
331        unknownType = new UnknownType();
332
333        // create the basic builtin symbols
334        rootPackage = new PackageSymbol(names.empty, null);
335        packages.put(names.empty, rootPackage);
336        final JavacMessages messages = JavacMessages.instance(context);
337        unnamedPackage = new PackageSymbol(names.empty, rootPackage) {
338                public String toString() {
339                    return messages.getLocalizedString("compiler.misc.unnamed.package");
340                }
341            };
342        noSymbol = new TypeSymbol(NIL, 0, names.empty, Type.noType, rootPackage) {
343            @DefinedBy(Api.LANGUAGE_MODEL)
344            public <R, P> R accept(ElementVisitor<R, P> v, P p) {
345                return v.visitUnknown(this, p);
346            }
347        };
348
349        // create the error symbols
350        errSymbol = new ClassSymbol(PUBLIC|STATIC|ACYCLIC, names.any, null, rootPackage);
351        errType = new ErrorType(errSymbol, Type.noType);
352
353        unknownSymbol = new ClassSymbol(PUBLIC|STATIC|ACYCLIC, names.fromString("<any?>"), null, rootPackage);
354        unknownSymbol.members_field = new Scope.ErrorScope(unknownSymbol);
355        unknownSymbol.type = unknownType;
356
357        // initialize builtin types
358        initType(byteType, "byte", "Byte");
359        initType(shortType, "short", "Short");
360        initType(charType, "char", "Character");
361        initType(intType, "int", "Integer");
362        initType(longType, "long", "Long");
363        initType(floatType, "float", "Float");
364        initType(doubleType, "double", "Double");
365        initType(booleanType, "boolean", "Boolean");
366        initType(voidType, "void", "Void");
367        initType(botType, "<nulltype>");
368        initType(errType, errSymbol);
369        initType(unknownType, unknownSymbol);
370
371        // the builtin class of all arrays
372        arrayClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Array, noSymbol);
373
374        // VGJ
375        boundClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Bound, noSymbol);
376        boundClass.members_field = new Scope.ErrorScope(boundClass);
377
378        // the builtin class of all methods
379        methodClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Method, noSymbol);
380        methodClass.members_field = new Scope.ErrorScope(boundClass);
381
382        // Create class to hold all predefined constants and operations.
383        predefClass = new ClassSymbol(PUBLIC|ACYCLIC, names.empty, rootPackage);
384        WriteableScope scope = WriteableScope.create(predefClass);
385        predefClass.members_field = scope;
386
387        // Get the initial completer for Symbols from the ClassFinder
388        initialCompleter = ClassFinder.instance(context).getCompleter();
389        rootPackage.completer = initialCompleter;
390        unnamedPackage.completer = initialCompleter;
391
392        // Enter symbols for basic types.
393        scope.enter(byteType.tsym);
394        scope.enter(shortType.tsym);
395        scope.enter(charType.tsym);
396        scope.enter(intType.tsym);
397        scope.enter(longType.tsym);
398        scope.enter(floatType.tsym);
399        scope.enter(doubleType.tsym);
400        scope.enter(booleanType.tsym);
401        scope.enter(errType.tsym);
402
403        // Enter symbol for the errSymbol
404        scope.enter(errSymbol);
405
406        classes.put(predefClass.fullname, predefClass);
407
408        // Enter predefined classes.
409        objectType = enterClass("java.lang.Object");
410        classType = enterClass("java.lang.Class");
411        stringType = enterClass("java.lang.String");
412        stringBufferType = enterClass("java.lang.StringBuffer");
413        stringBuilderType = enterClass("java.lang.StringBuilder");
414        cloneableType = enterClass("java.lang.Cloneable");
415        throwableType = enterClass("java.lang.Throwable");
416        serializableType = enterClass("java.io.Serializable");
417        serializedLambdaType = enterClass("java.lang.invoke.SerializedLambda");
418        methodHandleType = enterClass("java.lang.invoke.MethodHandle");
419        methodHandleLookupType = enterClass("java.lang.invoke.MethodHandles$Lookup");
420        methodTypeType = enterClass("java.lang.invoke.MethodType");
421        errorType = enterClass("java.lang.Error");
422        illegalArgumentExceptionType = enterClass("java.lang.IllegalArgumentException");
423        interruptedExceptionType = enterClass("java.lang.InterruptedException");
424        exceptionType = enterClass("java.lang.Exception");
425        runtimeExceptionType = enterClass("java.lang.RuntimeException");
426        classNotFoundExceptionType = enterClass("java.lang.ClassNotFoundException");
427        noClassDefFoundErrorType = enterClass("java.lang.NoClassDefFoundError");
428        noSuchFieldErrorType = enterClass("java.lang.NoSuchFieldError");
429        assertionErrorType = enterClass("java.lang.AssertionError");
430        cloneNotSupportedExceptionType = enterClass("java.lang.CloneNotSupportedException");
431        annotationType = enterClass("java.lang.annotation.Annotation");
432        classLoaderType = enterClass("java.lang.ClassLoader");
433        enumSym = enterClass(names.java_lang_Enum);
434        enumFinalFinalize =
435            new MethodSymbol(PROTECTED|FINAL|HYPOTHETICAL,
436                             names.finalize,
437                             new MethodType(List.<Type>nil(), voidType,
438                                            List.<Type>nil(), methodClass),
439                             enumSym);
440        listType = enterClass("java.util.List");
441        collectionsType = enterClass("java.util.Collections");
442        comparableType = enterClass("java.lang.Comparable");
443        comparatorType = enterClass("java.util.Comparator");
444        arraysType = enterClass("java.util.Arrays");
445        iterableType = enterClass("java.lang.Iterable");
446        iteratorType = enterClass("java.util.Iterator");
447        annotationTargetType = enterClass("java.lang.annotation.Target");
448        overrideType = enterClass("java.lang.Override");
449        retentionType = enterClass("java.lang.annotation.Retention");
450        deprecatedType = enterClass("java.lang.Deprecated");
451        suppressWarningsType = enterClass("java.lang.SuppressWarnings");
452        inheritedType = enterClass("java.lang.annotation.Inherited");
453        repeatableType = enterClass("java.lang.annotation.Repeatable");
454        documentedType = enterClass("java.lang.annotation.Documented");
455        elementTypeType = enterClass("java.lang.annotation.ElementType");
456        systemType = enterClass("java.lang.System");
457        autoCloseableType = enterClass("java.lang.AutoCloseable");
458        autoCloseableClose = new MethodSymbol(PUBLIC,
459                             names.close,
460                             new MethodType(List.<Type>nil(), voidType,
461                                            List.of(exceptionType), methodClass),
462                             autoCloseableType.tsym);
463        trustMeType = enterClass("java.lang.SafeVarargs");
464        nativeHeaderType = enterClass("java.lang.annotation.Native");
465        lambdaMetafactory = enterClass("java.lang.invoke.LambdaMetafactory");
466        functionalInterfaceType = enterClass("java.lang.FunctionalInterface");
467
468        synthesizeEmptyInterfaceIfMissing(autoCloseableType);
469        synthesizeEmptyInterfaceIfMissing(cloneableType);
470        synthesizeEmptyInterfaceIfMissing(serializableType);
471        synthesizeEmptyInterfaceIfMissing(lambdaMetafactory);
472        synthesizeEmptyInterfaceIfMissing(serializedLambdaType);
473        synthesizeBoxTypeIfMissing(doubleType);
474        synthesizeBoxTypeIfMissing(floatType);
475        synthesizeBoxTypeIfMissing(voidType);
476
477        // Enter a synthetic class that is used to mark internal
478        // proprietary classes in ct.sym.  This class does not have a
479        // class file.
480        proprietaryType = enterSyntheticAnnotation("sun.Proprietary+Annotation");
481
482        // Enter a synthetic class that is used to provide profile info for
483        // classes in ct.sym.  This class does not have a class file.
484        profileType = enterSyntheticAnnotation("jdk.Profile+Annotation");
485        MethodSymbol m = new MethodSymbol(PUBLIC | ABSTRACT, names.value, intType, profileType.tsym);
486        profileType.tsym.members().enter(m);
487
488        // Enter a class for arrays.
489        // The class implements java.lang.Cloneable and java.io.Serializable.
490        // It has a final length field and a clone method.
491        ClassType arrayClassType = (ClassType)arrayClass.type;
492        arrayClassType.supertype_field = objectType;
493        arrayClassType.interfaces_field = List.of(cloneableType, serializableType);
494        arrayClass.members_field = WriteableScope.create(arrayClass);
495        lengthVar = new VarSymbol(
496            PUBLIC | FINAL,
497            names.length,
498            intType,
499            arrayClass);
500        arrayClass.members().enter(lengthVar);
501        arrayCloneMethod = new MethodSymbol(
502            PUBLIC,
503            names.clone,
504            new MethodType(List.<Type>nil(), objectType,
505                           List.<Type>nil(), methodClass),
506            arrayClass);
507        arrayClass.members().enter(arrayCloneMethod);
508    }
509
510    /** Define a new class given its name and owner.
511     */
512    public ClassSymbol defineClass(Name name, Symbol owner) {
513        ClassSymbol c = new ClassSymbol(0, name, owner);
514        if (owner.kind == PCK)
515            Assert.checkNull(classes.get(c.flatname), c);
516        c.completer = initialCompleter;
517        return c;
518    }
519
520    /** Create a new toplevel or member class symbol with given name
521     *  and owner and enter in `classes' unless already there.
522     */
523    public ClassSymbol enterClass(Name name, TypeSymbol owner) {
524        Name flatname = TypeSymbol.formFlatName(name, owner);
525        ClassSymbol c = classes.get(flatname);
526        if (c == null) {
527            c = defineClass(name, owner);
528            classes.put(flatname, c);
529        } else if ((c.name != name || c.owner != owner) && owner.kind == TYP && c.owner.kind == PCK) {
530            // reassign fields of classes that might have been loaded with
531            // their flat names.
532            c.owner.members().remove(c);
533            c.name = name;
534            c.owner = owner;
535            c.fullname = ClassSymbol.formFullName(name, owner);
536        }
537        return c;
538    }
539
540    /**
541     * Creates a new toplevel class symbol with given flat name and
542     * given class (or source) file.
543     *
544     * @param flatName a fully qualified binary class name
545     * @param classFile the class file or compilation unit defining
546     * the class (may be {@code null})
547     * @return a newly created class symbol
548     * @throws AssertionError if the class symbol already exists
549     */
550    public ClassSymbol enterClass(Name flatName, JavaFileObject classFile) {
551        ClassSymbol cs = classes.get(flatName);
552        if (cs != null) {
553            String msg = Log.format("%s: completer = %s; class file = %s; source file = %s",
554                                    cs.fullname,
555                                    cs.completer,
556                                    cs.classfile,
557                                    cs.sourcefile);
558            throw new AssertionError(msg);
559        }
560        Name packageName = Convert.packagePart(flatName);
561        PackageSymbol owner = packageName.isEmpty()
562                                ? unnamedPackage
563                                : enterPackage(packageName);
564        cs = defineClass(Convert.shortName(flatName), owner);
565        cs.classfile = classFile;
566        classes.put(flatName, cs);
567        return cs;
568    }
569
570    /** Create a new member or toplevel class symbol with given flat name
571     *  and enter in `classes' unless already there.
572     */
573    public ClassSymbol enterClass(Name flatname) {
574        ClassSymbol c = classes.get(flatname);
575        if (c == null)
576            return enterClass(flatname, (JavaFileObject)null);
577        else
578            return c;
579    }
580
581    /** Check to see if a package exists, given its fully qualified name.
582     */
583    public boolean packageExists(Name fullname) {
584        return enterPackage(fullname).exists();
585    }
586
587    /** Make a package, given its fully qualified name.
588     */
589    public PackageSymbol enterPackage(Name fullname) {
590        PackageSymbol p = packages.get(fullname);
591        if (p == null) {
592            Assert.check(!fullname.isEmpty(), "rootPackage missing!");
593            p = new PackageSymbol(
594                Convert.shortName(fullname),
595                enterPackage(Convert.packagePart(fullname)));
596            p.completer = initialCompleter;
597            packages.put(fullname, p);
598        }
599        return p;
600    }
601
602    /** Make a package, given its unqualified name and enclosing package.
603     */
604    public PackageSymbol enterPackage(Name name, PackageSymbol owner) {
605        return enterPackage(TypeSymbol.formFullName(name, owner));
606    }
607}
608