1 /*
  2  * Copyright (c) 1999, 2024, 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 
 26 package com.sun.tools.javac.code;
 27 
 28 import java.util.Collection;
 29 import java.util.Collections;
 30 import java.util.EnumSet;
 31 import java.util.HashMap;
 32 import java.util.LinkedHashMap;
 33 import java.util.Map;
 34 
 35 import javax.lang.model.element.ElementVisitor;
 36 
 37 import com.sun.tools.javac.code.Scope.WriteableScope;
 38 import com.sun.tools.javac.code.Source.Feature;
 39 import com.sun.tools.javac.code.Symbol.ClassSymbol;
 40 import com.sun.tools.javac.code.Symbol.Completer;
 41 import com.sun.tools.javac.code.Symbol.CompletionFailure;
 42 import com.sun.tools.javac.code.Symbol.MethodSymbol;
 43 import com.sun.tools.javac.code.Symbol.ModuleSymbol;
 44 import com.sun.tools.javac.code.Symbol.PackageSymbol;
 45 import com.sun.tools.javac.code.Symbol.RootPackageSymbol;
 46 import com.sun.tools.javac.code.Symbol.TypeSymbol;
 47 import com.sun.tools.javac.code.Symbol.VarSymbol;
 48 import com.sun.tools.javac.code.Type.BottomType;
 49 import com.sun.tools.javac.code.Type.ClassType;
 50 import com.sun.tools.javac.code.Type.ErrorType;
 51 import com.sun.tools.javac.code.Type.JCPrimitiveType;
 52 import com.sun.tools.javac.code.Type.JCVoidType;
 53 import com.sun.tools.javac.code.Type.MethodType;
 54 import com.sun.tools.javac.code.Type.UnknownType;
 55 import com.sun.tools.javac.code.Types.UniqueType;
 56 import com.sun.tools.javac.comp.Modules;
 57 import com.sun.tools.javac.jvm.Target;
 58 import com.sun.tools.javac.util.Assert;
 59 import com.sun.tools.javac.util.Context;
 60 import com.sun.tools.javac.util.Convert;
 61 import com.sun.tools.javac.util.DefinedBy;
 62 import com.sun.tools.javac.util.DefinedBy.Api;
 63 import com.sun.tools.javac.util.Iterators;
 64 import com.sun.tools.javac.util.JavacMessages;
 65 import com.sun.tools.javac.util.List;
 66 import com.sun.tools.javac.util.Name;
 67 import com.sun.tools.javac.util.Names;
 68 
 69 import static com.sun.tools.javac.code.Flags.*;
 70 import static com.sun.tools.javac.code.Kinds.Kind.*;
 71 import static com.sun.tools.javac.code.TypeTag.*;
 72 
 73 /** A class that defines all predefined constants and operators
 74  *  as well as special classes such as java.lang.Object, which need
 75  *  to be known to the compiler. All symbols are held in instance
 76  *  fields. This makes it possible to work in multiple concurrent
 77  *  projects, which might use different class files for library classes.
 78  *
 79  *  <p><b>This is NOT part of any supported API.
 80  *  If you write code that depends on this, you do so at your own risk.
 81  *  This code and its internal interfaces are subject to change or
 82  *  deletion without notice.</b>
 83  */
 84 public class Symtab {
 85     /** The context key for the symbol table. */
 86     protected static final Context.Key<Symtab> symtabKey = new Context.Key<>();
 87 
 88     /** Get the symbol table instance. */
 89     public static Symtab instance(Context context) {
 90         Symtab instance = context.get(symtabKey);
 91         if (instance == null)
 92             instance = new Symtab(context);
 93         return instance;
 94     }
 95 
 96     /** Builtin types.
 97      */
 98     public final JCPrimitiveType byteType = new JCPrimitiveType(BYTE, null);
 99     public final JCPrimitiveType charType = new JCPrimitiveType(CHAR, null);
100     public final JCPrimitiveType shortType = new JCPrimitiveType(SHORT, null);
101     public final JCPrimitiveType intType = new JCPrimitiveType(INT, null);
102     public final JCPrimitiveType longType = new JCPrimitiveType(LONG, null);
103     public final JCPrimitiveType floatType = new JCPrimitiveType(FLOAT, null);
104     public final JCPrimitiveType doubleType = new JCPrimitiveType(DOUBLE, null);
105     public final JCPrimitiveType booleanType = new JCPrimitiveType(BOOLEAN, null);
106     public final Type botType = new BottomType();
107     public final JCVoidType voidType = new JCVoidType();
108 
109     private final Names names;
110     private final JavacMessages messages;
111     private final Completer initialCompleter;
112     private final Completer moduleCompleter;
113 
114     /** A symbol for the unnamed module.
115      */
116     public final ModuleSymbol unnamedModule;
117 
118     /** The error module.
119      */
120     public final ModuleSymbol errModule;
121 
122     /** A symbol for no module, for use with -source 8 or less
123      */
124     public final ModuleSymbol noModule;
125 
126     /** A symbol for the root package.
127      */
128     public final PackageSymbol rootPackage;
129 
130     /** A symbol that stands for a missing symbol.
131      */
132     public final TypeSymbol noSymbol;
133 
134     /** The error symbol.
135      */
136     public final ClassSymbol errSymbol;
137 
138     /** The unknown symbol.
139      */
140     public final ClassSymbol unknownSymbol;
141 
142     /** A value for the errType, with a originalType of noType */
143     public final Type errType;
144 
145     /** A value for the unknown type. */
146     public final Type unknownType;
147 
148     /** The builtin type of all arrays. */
149     public final ClassSymbol arrayClass;
150     public final MethodSymbol arrayCloneMethod;
151 
152     /** VGJ: The (singleton) type of all bound types. */
153     public final ClassSymbol boundClass;
154 
155     /** The builtin type of all methods. */
156     public final ClassSymbol methodClass;
157 
158     /** A symbol for the java.base module.
159      */
160     public final ModuleSymbol java_base;
161 
162     /** Predefined types.
163      */
164     public final Type objectType;
165     public final Type objectMethodsType;
166     public final Type exactConversionsSupportType;
167     public final Type objectsType;
168     public final Type classType;
169     public final Type classLoaderType;
170     public final Type stringType;
171     public final Type stringBufferType;
172     public final Type stringBuilderType;
173     public final Type cloneableType;
174     public final Type serializableType;
175     public final Type serializedLambdaType;
176     public final Type varHandleType;
177     public final Type methodHandleType;
178     public final Type methodHandlesType;
179     public final Type methodHandleLookupType;
180     public final Type methodTypeType;
181     public final Type nativeHeaderType;
182     public final Type throwableType;
183     public final Type errorType;
184     public final Type interruptedExceptionType;
185     public final Type illegalArgumentExceptionType;
186     public final Type exceptionType;
187     public final Type runtimeExceptionType;
188     public final Type classNotFoundExceptionType;
189     public final Type noClassDefFoundErrorType;
190     public final Type noSuchFieldErrorType;
191     public final Type assertionErrorType;
192     public final Type incompatibleClassChangeErrorType;
193     public final Type cloneNotSupportedExceptionType;
194     public final Type matchExceptionType;
195     public final Type annotationType;
196     public final TypeSymbol enumSym;
197     public final Type listType;
198     public final Type collectionsType;
199     public final Type comparableType;
200     public final Type comparatorType;
201     public final Type arraysType;
202     public final Type iterableType;
203     public final Type iteratorType;
204     public final Type annotationTargetType;
205     public final Type overrideType;
206     public final Type retentionType;
207     public final Type deprecatedType;
208     public final Type suppressWarningsType;
209     public final Type supplierType;
210     public final Type inheritedType;
211     public final Type profileType;
212     public final Type proprietaryType;
213     public final Type systemType;
214     public final Type autoCloseableType;
215     public final Type trustMeType;
216     public final Type lambdaMetafactory;
217     public final Type stringConcatFactory;
218     public final Type repeatableType;
219     public final Type documentedType;
220     public final Type elementTypeType;
221     public final Type functionalInterfaceType;
222     public final Type previewFeatureType;
223     public final Type previewFeatureInternalType;
224     public final Type restrictedType;
225     public final Type typeDescriptorType;
226     public final Type recordType;
227     public final Type switchBootstrapsType;
228     public final Type constantBootstrapsType;
229     public final Type valueBasedType;
230     public final Type valueBasedInternalType;
231     public final Type classDescType;
232     public final Type enumDescType;
233 
234     // For serialization lint checking
235     public final Type objectStreamFieldType;
236     public final Type objectInputStreamType;
237     public final Type objectOutputStreamType;
238     public final Type ioExceptionType;
239     public final Type objectStreamExceptionType;
240     // For externalization lint checking
241     public final Type externalizableType;
242     public final Type objectInputType;
243     public final Type objectOutputType;
244 
245     /** The symbol representing the length field of an array.
246      */
247     public final VarSymbol lengthVar;
248 
249     /** The symbol representing the final finalize method on enums */
250     public final MethodSymbol enumFinalFinalize;
251 
252     /** The symbol representing the close method on TWR AutoCloseable type */
253     public final MethodSymbol autoCloseableClose;
254 
255     /** The predefined type that belongs to a tag.
256      */
257     public final Type[] typeOfTag = new Type[TypeTag.getTypeTagCount()];
258 
259     /** The name of the class that belongs to a basic type tag.
260      */
261     public final Name[] boxedName = new Name[TypeTag.getTypeTagCount()];
262 
263     /** A hashtable containing the encountered top-level and member classes,
264      *  indexed by flat names. The table does not contain local classes.
265      *  It should be updated from the outside to reflect classes defined
266      *  by compiled source files.
267      */
268     private final Map<Name, Map<ModuleSymbol,ClassSymbol>> classes = new HashMap<>();
269 
270     /** A hashtable containing the encountered packages.
271      *  the table should be updated from outside to reflect packages defined
272      *  by compiled source files.
273      */
274     private final Map<Name, Map<ModuleSymbol,PackageSymbol>> packages = new HashMap<>();
275 
276     /** A hashtable giving the encountered modules.
277      */
278     private final Map<Name, ModuleSymbol> modules = new LinkedHashMap<>();
279 
280     private final Map<Types.UniqueType, VarSymbol> classFields = new HashMap<>();
281 
282     public VarSymbol getClassField(Type type, Types types) {
283         return classFields.computeIfAbsent(
284             new UniqueType(type, types), k -> {
285                 Type arg = null;
286                 if (type.getTag() == ARRAY || type.getTag() == CLASS)
287                     arg = types.erasure(type);
288                 else if (type.isPrimitiveOrVoid())
289                     arg = types.boxedClass(type).type;
290                 else
291                     throw new AssertionError(type);
292 
293                 Type t = new ClassType(
294                     classType.getEnclosingType(), List.of(arg), classType.tsym);
295                 return new VarSymbol(
296                     STATIC | PUBLIC | FINAL, names._class, t, type.tsym);
297             });
298     }
299 
300     public void initType(Type type, ClassSymbol c) {
301         type.tsym = c;
302         typeOfTag[type.getTag().ordinal()] = type;
303     }
304 
305     public void initType(Type type, String name) {
306         initType(
307             type,
308             new ClassSymbol(
309                 PUBLIC, names.fromString(name), type, rootPackage));
310     }
311 
312     public void initType(Type type, String name, String bname) {
313         initType(type, name);
314         boxedName[type.getTag().ordinal()] = names.fromString("java.lang." + bname);
315     }
316 
317     /** The class symbol that owns all predefined symbols.
318      */
319     public final ClassSymbol predefClass;
320 
321     /** Enter a class into symbol table.
322      *  @param s The name of the class.
323      */
324     private Type enterClass(String s) {
325         return enterClass(java_base, names.fromString(s)).type;
326     }
327 
328     public void synthesizeEmptyInterfaceIfMissing(final Type type) {
329         final Completer completer = type.tsym.completer;
330         type.tsym.completer = new Completer() {
331             @Override
332             public void complete(Symbol sym) throws CompletionFailure {
333                 try {
334                     completer.complete(sym);
335                 } catch (CompletionFailure e) {
336                     sym.flags_field |= (PUBLIC | INTERFACE);
337                     ((ClassType) sym.type).supertype_field = objectType;
338                 }
339             }
340 
341             @Override
342             public boolean isTerminal() {
343                 return completer.isTerminal();
344             }
345         };
346     }
347 
348     public void synthesizeBoxTypeIfMissing(final Type type) {
349         ClassSymbol sym = enterClass(java_base, boxedName[type.getTag().ordinal()]);
350         final Completer completer = sym.completer;
351         sym.completer = new Completer() {
352             @Override
353             public void complete(Symbol sym) throws CompletionFailure {
354                 try {
355                     completer.complete(sym);
356                 } catch (CompletionFailure e) {
357                     sym.flags_field |= PUBLIC;
358                     ((ClassType) sym.type).supertype_field = objectType;
359                     MethodSymbol boxMethod =
360                         new MethodSymbol(PUBLIC | STATIC, names.valueOf,
361                                          new MethodType(List.of(type), sym.type,
362                                 List.nil(), methodClass),
363                             sym);
364                     sym.members().enter(boxMethod);
365                     MethodSymbol unboxMethod =
366                         new MethodSymbol(PUBLIC,
367                             type.tsym.name.append(names.Value), // x.intValue()
368                             new MethodType(List.nil(), type,
369                                 List.nil(), methodClass),
370                             sym);
371                     sym.members().enter(unboxMethod);
372                 }
373             }
374 
375             @Override
376             public boolean isTerminal() {
377                 return completer.isTerminal();
378             }
379         };
380     }
381 
382     // Enter a synthetic class that is used to mark classes in ct.sym.
383     // This class does not have a class file.
384     private Type enterSyntheticAnnotation(String name) {
385         // for now, leave the module null, to prevent problems from synthesizing the
386         // existence of a class in any specific module, including noModule
387         ClassType type = (ClassType)enterClass(java_base, names.fromString(name)).type;
388         ClassSymbol sym = (ClassSymbol)type.tsym;
389         sym.completer = Completer.NULL_COMPLETER;
390         sym.flags_field = PUBLIC|ACYCLIC|ANNOTATION|INTERFACE;
391         sym.erasure_field = type;
392         sym.members_field = WriteableScope.create(sym);
393         type.typarams_field = List.nil();
394         type.allparams_field = List.nil();
395         type.supertype_field = annotationType;
396         type.interfaces_field = List.nil();
397         return type;
398     }
399 
400     /** Constructor; enters all predefined identifiers and operators
401      *  into symbol table.
402      */
403     @SuppressWarnings("this-escape")
404     protected Symtab(Context context) throws CompletionFailure {
405         context.put(symtabKey, this);
406 
407         names = Names.instance(context);
408 
409         // Create the unknown type
410         unknownType = new UnknownType();
411 
412         messages = JavacMessages.instance(context);
413 
414         MissingInfoHandler missingInfoHandler = MissingInfoHandler.instance(context);
415 
416         Target target = Target.instance(context);
417         rootPackage = new RootPackageSymbol(names.empty, null,
418                                             missingInfoHandler,
419                                             target.runtimeUseNestAccess());
420 
421         // create the basic builtin symbols
422         unnamedModule = new ModuleSymbol(names.empty, null) {
423                 {
424                     directives = List.nil();
425                     exports = List.nil();
426                     provides = List.nil();
427                     uses = List.nil();
428                     ModuleSymbol java_base = enterModule(names.java_base);
429                     com.sun.tools.javac.code.Directive.RequiresDirective d =
430                             new com.sun.tools.javac.code.Directive.RequiresDirective(java_base,
431                                     EnumSet.of(com.sun.tools.javac.code.Directive.RequiresFlag.MANDATED));
432                     requires = List.of(d);
433                 }
434                 @Override
435                 public String toString() {
436                     return messages.getLocalizedString("compiler.misc.unnamed.module");
437                 }
438             };
439         addRootPackageFor(unnamedModule);
440         unnamedModule.enclosedPackages = unnamedModule.enclosedPackages.prepend(unnamedModule.unnamedPackage);
441 
442         errModule = new ModuleSymbol(names.empty, null) {
443                 {
444                     directives = List.nil();
445                     exports = List.nil();
446                     provides = List.nil();
447                     uses = List.nil();
448                     ModuleSymbol java_base = enterModule(names.java_base);
449                     com.sun.tools.javac.code.Directive.RequiresDirective d =
450                             new com.sun.tools.javac.code.Directive.RequiresDirective(java_base,
451                                     EnumSet.of(com.sun.tools.javac.code.Directive.RequiresFlag.MANDATED));
452                     requires = List.of(d);
453                 }
454             };
455         addRootPackageFor(errModule);
456 
457         noModule = new ModuleSymbol(names.empty, null) {
458             @Override public boolean isNoModule() {
459                 return true;
460             }
461         };
462         addRootPackageFor(noModule);
463 
464         noSymbol = new TypeSymbol(NIL, 0, names.empty, Type.noType, rootPackage) {
465             @Override @DefinedBy(Api.LANGUAGE_MODEL)
466             public <R, P> R accept(ElementVisitor<R, P> v, P p) {
467                 return v.visitUnknown(this, p);
468             }
469         };
470 
471         // create the error symbols
472         errSymbol = new ClassSymbol(PUBLIC|STATIC|ACYCLIC, names.any, null, rootPackage);
473         errType = new ErrorType(errSymbol, Type.noType);
474 
475         unknownSymbol = new ClassSymbol(PUBLIC|STATIC|ACYCLIC, names.fromString("<any?>"), null, rootPackage);
476         unknownSymbol.members_field = new Scope.ErrorScope(unknownSymbol);
477         unknownSymbol.type = unknownType;
478 
479         // initialize builtin types
480         initType(byteType, "byte", "Byte");
481         initType(shortType, "short", "Short");
482         initType(charType, "char", "Character");
483         initType(intType, "int", "Integer");
484         initType(longType, "long", "Long");
485         initType(floatType, "float", "Float");
486         initType(doubleType, "double", "Double");
487         initType(booleanType, "boolean", "Boolean");
488         initType(voidType, "void", "Void");
489         initType(botType, "<nulltype>");
490         initType(errType, errSymbol);
491         initType(unknownType, unknownSymbol);
492 
493         // the builtin class of all arrays
494         arrayClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Array, noSymbol);
495 
496         // VGJ
497         boundClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Bound, noSymbol);
498         boundClass.members_field = new Scope.ErrorScope(boundClass);
499 
500         // the builtin class of all methods
501         methodClass = new ClassSymbol(PUBLIC|ACYCLIC, names.Method, noSymbol);
502         methodClass.members_field = new Scope.ErrorScope(boundClass);
503 
504         // Create class to hold all predefined constants and operations.
505         predefClass = new ClassSymbol(PUBLIC|ACYCLIC, names.empty, rootPackage);
506         WriteableScope scope = WriteableScope.create(predefClass);
507         predefClass.members_field = scope;
508 
509         // Get the initial completer for Symbols from the ClassFinder
510         initialCompleter = ClassFinder.instance(context).getCompleter();
511         rootPackage.members_field = WriteableScope.create(rootPackage);
512 
513         // Enter symbols for basic types.
514         scope.enter(byteType.tsym);
515         scope.enter(shortType.tsym);
516         scope.enter(charType.tsym);
517         scope.enter(intType.tsym);
518         scope.enter(longType.tsym);
519         scope.enter(floatType.tsym);
520         scope.enter(doubleType.tsym);
521         scope.enter(booleanType.tsym);
522         scope.enter(errType.tsym);
523 
524         // Enter symbol for the errSymbol
525         scope.enter(errSymbol);
526 
527         Source source = Source.instance(context);
528         if (Feature.MODULES.allowedInSource(source)) {
529             java_base = enterModule(names.java_base);
530             //avoid completing java.base during the Symtab initialization
531             java_base.completer = Completer.NULL_COMPLETER;
532             java_base.visiblePackages = Collections.emptyMap();
533         } else {
534             java_base = noModule;
535         }
536 
537         // Get the initial completer for ModuleSymbols from Modules
538         moduleCompleter = Modules.instance(context).getCompleter();
539 
540         // Enter predefined classes. All are assumed to be in the java.base module.
541         objectType = enterClass("java.lang.Object");
542         objectMethodsType = enterClass("java.lang.runtime.ObjectMethods");
543         exactConversionsSupportType = enterClass("java.lang.runtime.ExactConversionsSupport");
544         objectsType = enterClass("java.util.Objects");
545         classType = enterClass("java.lang.Class");
546         stringType = enterClass("java.lang.String");
547         stringBufferType = enterClass("java.lang.StringBuffer");
548         stringBuilderType = enterClass("java.lang.StringBuilder");
549         cloneableType = enterClass("java.lang.Cloneable");
550         throwableType = enterClass("java.lang.Throwable");
551         serializableType = enterClass("java.io.Serializable");
552         serializedLambdaType = enterClass("java.lang.invoke.SerializedLambda");
553         varHandleType = enterClass("java.lang.invoke.VarHandle");
554         methodHandleType = enterClass("java.lang.invoke.MethodHandle");
555         methodHandlesType = enterClass("java.lang.invoke.MethodHandles");
556         methodHandleLookupType = enterClass("java.lang.invoke.MethodHandles$Lookup");
557         methodTypeType = enterClass("java.lang.invoke.MethodType");
558         errorType = enterClass("java.lang.Error");
559         illegalArgumentExceptionType = enterClass("java.lang.IllegalArgumentException");
560         interruptedExceptionType = enterClass("java.lang.InterruptedException");
561         exceptionType = enterClass("java.lang.Exception");
562         runtimeExceptionType = enterClass("java.lang.RuntimeException");
563         classNotFoundExceptionType = enterClass("java.lang.ClassNotFoundException");
564         noClassDefFoundErrorType = enterClass("java.lang.NoClassDefFoundError");
565         noSuchFieldErrorType = enterClass("java.lang.NoSuchFieldError");
566         assertionErrorType = enterClass("java.lang.AssertionError");
567         incompatibleClassChangeErrorType = enterClass("java.lang.IncompatibleClassChangeError");
568         cloneNotSupportedExceptionType = enterClass("java.lang.CloneNotSupportedException");
569         matchExceptionType = enterClass("java.lang.MatchException");
570         annotationType = enterClass("java.lang.annotation.Annotation");
571         classLoaderType = enterClass("java.lang.ClassLoader");
572         enumSym = enterClass(java_base, names.java_lang_Enum);
573         enumFinalFinalize =
574             new MethodSymbol(PROTECTED|FINAL|HYPOTHETICAL,
575                              names.finalize,
576                              new MethodType(List.nil(), voidType,
577                                             List.nil(), methodClass),
578                              enumSym);
579         listType = enterClass("java.util.List");
580         collectionsType = enterClass("java.util.Collections");
581         comparableType = enterClass("java.lang.Comparable");
582         comparatorType = enterClass("java.util.Comparator");
583         arraysType = enterClass("java.util.Arrays");
584         iterableType = enterClass("java.lang.Iterable");
585         iteratorType = enterClass("java.util.Iterator");
586         annotationTargetType = enterClass("java.lang.annotation.Target");
587         overrideType = enterClass("java.lang.Override");
588         retentionType = enterClass("java.lang.annotation.Retention");
589         deprecatedType = enterClass("java.lang.Deprecated");
590         suppressWarningsType = enterClass("java.lang.SuppressWarnings");
591         supplierType = enterClass("java.util.function.Supplier");
592         inheritedType = enterClass("java.lang.annotation.Inherited");
593         repeatableType = enterClass("java.lang.annotation.Repeatable");
594         documentedType = enterClass("java.lang.annotation.Documented");
595         elementTypeType = enterClass("java.lang.annotation.ElementType");
596         systemType = enterClass("java.lang.System");
597         autoCloseableType = enterClass("java.lang.AutoCloseable");
598         autoCloseableClose = new MethodSymbol(PUBLIC,
599                              names.close,
600                              new MethodType(List.nil(), voidType,
601                                             List.of(exceptionType), methodClass),
602                              autoCloseableType.tsym);
603         trustMeType = enterClass("java.lang.SafeVarargs");
604         nativeHeaderType = enterClass("java.lang.annotation.Native");
605         lambdaMetafactory = enterClass("java.lang.invoke.LambdaMetafactory");
606         stringConcatFactory = enterClass("java.lang.invoke.StringConcatFactory");
607         functionalInterfaceType = enterClass("java.lang.FunctionalInterface");
608         previewFeatureType = enterClass("jdk.internal.javac.PreviewFeature");
609         previewFeatureInternalType = enterSyntheticAnnotation("jdk.internal.PreviewFeature+Annotation");
610         restrictedType = enterClass("jdk.internal.javac.Restricted");
611         typeDescriptorType = enterClass("java.lang.invoke.TypeDescriptor");
612         recordType = enterClass("java.lang.Record");
613         switchBootstrapsType = enterClass("java.lang.runtime.SwitchBootstraps");
614         constantBootstrapsType = enterClass("java.lang.invoke.ConstantBootstraps");
615         valueBasedType = enterClass("jdk.internal.ValueBased");
616         valueBasedInternalType = enterSyntheticAnnotation("jdk.internal.ValueBased+Annotation");
617         classDescType = enterClass("java.lang.constant.ClassDesc");
618         enumDescType = enterClass("java.lang.Enum$EnumDesc");
619         // For serialization lint checking
620         objectStreamFieldType = enterClass("java.io.ObjectStreamField");
621         objectInputStreamType = enterClass("java.io.ObjectInputStream");
622         objectOutputStreamType = enterClass("java.io.ObjectOutputStream");
623         ioExceptionType = enterClass("java.io.IOException");
624         objectStreamExceptionType = enterClass("java.io.ObjectStreamException");
625         externalizableType = enterClass("java.io.Externalizable");
626         objectInputType  = enterClass("java.io.ObjectInput");
627         objectOutputType = enterClass("java.io.ObjectOutput");
628         synthesizeEmptyInterfaceIfMissing(autoCloseableType);
629         synthesizeEmptyInterfaceIfMissing(cloneableType);
630         synthesizeEmptyInterfaceIfMissing(serializableType);
631         synthesizeEmptyInterfaceIfMissing(lambdaMetafactory);
632         synthesizeEmptyInterfaceIfMissing(serializedLambdaType);
633         synthesizeEmptyInterfaceIfMissing(stringConcatFactory);
634         synthesizeBoxTypeIfMissing(doubleType);
635         synthesizeBoxTypeIfMissing(floatType);
636         synthesizeBoxTypeIfMissing(voidType);
637 
638         // Enter a synthetic class that is used to mark internal
639         // proprietary classes in ct.sym.  This class does not have a
640         // class file.
641         proprietaryType = enterSyntheticAnnotation("sun.Proprietary+Annotation");
642 
643         // Enter a synthetic class that is used to provide profile info for
644         // classes in ct.sym.  This class does not have a class file.
645         profileType = enterSyntheticAnnotation("jdk.Profile+Annotation");
646         MethodSymbol m = new MethodSymbol(PUBLIC | ABSTRACT, names.value, intType, profileType.tsym);
647         profileType.tsym.members().enter(m);
648 
649         // Enter a class for arrays.
650         // The class implements java.lang.Cloneable and java.io.Serializable.
651         // It has a final length field and a clone method.
652         ClassType arrayClassType = (ClassType)arrayClass.type;
653         arrayClassType.supertype_field = objectType;
654         arrayClassType.interfaces_field = List.of(cloneableType, serializableType);
655         arrayClass.members_field = WriteableScope.create(arrayClass);
656         lengthVar = new VarSymbol(
657             PUBLIC | FINAL,
658             names.length,
659             intType,
660             arrayClass);
661         arrayClass.members().enter(lengthVar);
662         arrayCloneMethod = new MethodSymbol(
663             PUBLIC,
664             names.clone,
665             new MethodType(List.nil(), objectType,
666                            List.nil(), methodClass),
667             arrayClass);
668         arrayClass.members().enter(arrayCloneMethod);
669 
670         if (java_base != noModule)
671             java_base.completer = moduleCompleter::complete; //bootstrap issues
672 
673     }
674 
675     /** Define a new class given its name and owner.
676      */
677     public ClassSymbol defineClass(Name name, Symbol owner) {
678         ClassSymbol c = new ClassSymbol(0, name, owner);
679         c.completer = initialCompleter;
680         return c;
681     }
682 
683     /** Create a new toplevel or member class symbol with given name
684      *  and owner and enter in `classes' unless already there.
685      */
686     public ClassSymbol enterClass(ModuleSymbol msym, Name name, TypeSymbol owner) {
687         Assert.checkNonNull(msym);
688         Name flatname = TypeSymbol.formFlatName(name, owner);
689         ClassSymbol c = getClass(msym, flatname);
690         if (c == null) {
691             c = defineClass(name, owner);
692             doEnterClass(msym, c);
693         } else if ((c.name != name || c.owner != owner) && owner.kind == TYP &&
694                    c.owner.kind == PCK && ((c.flags_field & FROM_SOURCE) == 0)) {
695             // reassign fields of classes that might have been loaded with
696             // their flat names.
697             c.owner.members().remove(c);
698             c.name = name;
699             c.owner = owner;
700             c.fullname = ClassSymbol.formFullName(name, owner);
701         }
702         return c;
703     }
704 
705     public ClassSymbol getClass(ModuleSymbol msym, Name flatName) {
706         Assert.checkNonNull(msym, flatName::toString);
707         return classes.getOrDefault(flatName, Collections.emptyMap()).get(msym);
708     }
709 
710     public PackageSymbol lookupPackage(ModuleSymbol msym, Name flatName) {
711         return lookupPackage(msym, flatName, false);
712     }
713 
714     private PackageSymbol lookupPackage(ModuleSymbol msym, Name flatName, boolean onlyExisting) {
715         Assert.checkNonNull(msym);
716 
717         if (flatName.isEmpty()) {
718             //unnamed packages only from the current module - visiblePackages contains *root* package, not unnamed package!
719             return msym.unnamedPackage;
720         }
721 
722         if (msym == noModule) {
723             return enterPackage(msym, flatName);
724         }
725 
726         msym.complete();
727 
728         PackageSymbol pack;
729 
730         pack = msym.visiblePackages.get(flatName);
731 
732         if (pack != null)
733             return pack;
734 
735         pack = getPackage(msym, flatName);
736 
737         if ((pack != null && pack.exists()) || onlyExisting)
738             return pack;
739 
740         boolean dependsOnUnnamed = msym.requires != null &&
741                                    msym.requires.stream()
742                                                 .map(rd -> rd.module)
743                                                 .anyMatch(mod -> mod == unnamedModule);
744 
745         if (dependsOnUnnamed) {
746             //msyms depends on the unnamed module, for which we generally don't know
747             //the list of packages it "exports" ahead of time. So try to lookup the package in the
748             //current module, and in the unnamed module and see if it exists in one of them
749             PackageSymbol unnamedPack = getPackage(unnamedModule, flatName);
750 
751             if (unnamedPack != null && unnamedPack.exists()) {
752                 msym.visiblePackages.put(unnamedPack.fullname, unnamedPack);
753                 return unnamedPack;
754             }
755 
756             pack = enterPackage(msym, flatName);
757             pack.complete();
758             if (pack.exists())
759                 return pack;
760 
761             unnamedPack = enterPackage(unnamedModule, flatName);
762             unnamedPack.complete();
763             if (unnamedPack.exists()) {
764                 msym.visiblePackages.put(unnamedPack.fullname, unnamedPack);
765                 return unnamedPack;
766             }
767 
768             return pack;
769         }
770 
771         return enterPackage(msym, flatName);
772     }
773 
774     private static final Map<ModuleSymbol, ClassSymbol> EMPTY = new HashMap<>();
775 
776     public void removeClass(ModuleSymbol msym, Name flatName) {
777         classes.getOrDefault(flatName, EMPTY).remove(msym);
778     }
779 
780     public Iterable<ClassSymbol> getAllClasses() {
781         return () -> Iterators.createCompoundIterator(classes.values(), v -> v.values().iterator());
782     }
783 
784     private void doEnterClass(ModuleSymbol msym, ClassSymbol cs) {
785         classes.computeIfAbsent(cs.flatname, n -> new HashMap<>()).put(msym, cs);
786     }
787 
788     /** Create a new member or toplevel class symbol with given flat name
789      *  and enter in `classes' unless already there.
790      */
791     public ClassSymbol enterClass(ModuleSymbol msym, Name flatname) {
792         Assert.checkNonNull(msym);
793         PackageSymbol ps = lookupPackage(msym, Convert.packagePart(flatname));
794         Assert.checkNonNull(ps);
795         Assert.checkNonNull(ps.modle);
796         ClassSymbol c = getClass(ps.modle, flatname);
797         if (c == null) {
798             c = defineClass(Convert.shortName(flatname), ps);
799             doEnterClass(ps.modle, c);
800             return c;
801         } else
802             return c;
803     }
804 
805     /** Check to see if a package exists, given its fully qualified name.
806      */
807     public boolean packageExists(ModuleSymbol msym, Name fullname) {
808         Assert.checkNonNull(msym);
809         PackageSymbol pack = lookupPackage(msym, fullname, true);
810         return pack != null && pack.exists();
811     }
812 
813     /** Make a package, given its fully qualified name.
814      */
815     public PackageSymbol enterPackage(ModuleSymbol currModule, Name fullname) {
816         Assert.checkNonNull(currModule);
817         PackageSymbol p = getPackage(currModule, fullname);
818         if (p == null) {
819             Assert.check(!fullname.isEmpty(), () -> "rootPackage missing!; currModule: " + currModule);
820             p = new PackageSymbol(
821                     Convert.shortName(fullname),
822                     enterPackage(currModule, Convert.packagePart(fullname)));
823             p.completer = initialCompleter;
824             p.modle = currModule;
825             doEnterPackage(currModule, p);
826         }
827         return p;
828     }
829 
830     private void doEnterPackage(ModuleSymbol msym, PackageSymbol pack) {
831         packages.computeIfAbsent(pack.fullname, n -> new HashMap<>()).put(msym, pack);
832         msym.enclosedPackages = msym.enclosedPackages.prepend(pack);
833     }
834 
835     private void addRootPackageFor(ModuleSymbol module) {
836         doEnterPackage(module, rootPackage);
837         PackageSymbol unnamedPackage = new PackageSymbol(names.empty, rootPackage) {
838                 @Override
839                 public String toString() {
840                     return messages.getLocalizedString("compiler.misc.unnamed.package");
841                 }
842             };
843         unnamedPackage.modle = module;
844         //we cannot use a method reference below, as initialCompleter might be null now
845         unnamedPackage.completer = s -> initialCompleter.complete(s);
846         unnamedPackage.flags_field |= EXISTS;
847         module.unnamedPackage = unnamedPackage;
848     }
849 
850     public PackageSymbol getPackage(ModuleSymbol module, Name fullname) {
851         return packages.getOrDefault(fullname, Collections.emptyMap()).get(module);
852     }
853 
854     public ModuleSymbol enterModule(Name name) {
855         ModuleSymbol msym = modules.get(name);
856         if (msym == null) {
857             msym = ModuleSymbol.create(name, names.module_info);
858             addRootPackageFor(msym);
859             msym.completer = s -> moduleCompleter.complete(s); //bootstrap issues
860             modules.put(name, msym);
861         }
862         return msym;
863     }
864 
865     public ModuleSymbol getModule(Name name) {
866         return modules.get(name);
867     }
868 
869     //temporary:
870     public ModuleSymbol inferModule(Name packageName) {
871         if (packageName.isEmpty())
872             return java_base == noModule ? noModule : unnamedModule;//!
873 
874         ModuleSymbol msym = null;
875         Map<ModuleSymbol,PackageSymbol> map = packages.get(packageName);
876         if (map == null)
877             return null;
878         for (Map.Entry<ModuleSymbol,PackageSymbol> e: map.entrySet()) {
879             if (!e.getValue().members().isEmpty()) {
880                 if (msym == null) {
881                     msym = e.getKey();
882                 } else {
883                     return null;
884                 }
885             }
886         }
887         return msym;
888     }
889 
890     public List<ModuleSymbol> listPackageModules(Name packageName) {
891         if (packageName.isEmpty())
892             return List.nil();
893 
894         List<ModuleSymbol> result = List.nil();
895         Map<ModuleSymbol,PackageSymbol> map = packages.get(packageName);
896         if (map != null) {
897             for (Map.Entry<ModuleSymbol, PackageSymbol> e: map.entrySet()) {
898                 if (!e.getValue().members().isEmpty()) {
899                     result = result.prepend(e.getKey());
900                 }
901             }
902         }
903         return result;
904     }
905 
906     public Collection<ModuleSymbol> getAllModules() {
907         return modules.values();
908     }
909 
910     public Iterable<ClassSymbol> getClassesForName(Name candidate) {
911         return classes.getOrDefault(candidate, Collections.emptyMap()).values();
912     }
913 
914     public Iterable<PackageSymbol> getPackagesForName(Name candidate) {
915         return packages.getOrDefault(candidate, Collections.emptyMap()).values();
916     }
917 }