1 /*
  2  * Copyright (c) 1999, 2023, 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.comp;
 27 
 28 import java.util.Map;
 29 import java.util.Optional;
 30 
 31 import javax.tools.JavaFileObject;
 32 import javax.tools.JavaFileManager;
 33 
 34 import com.sun.tools.javac.code.*;
 35 import com.sun.tools.javac.code.Kinds.KindName;
 36 import com.sun.tools.javac.code.Kinds.KindSelector;
 37 import com.sun.tools.javac.code.Scope.*;
 38 import com.sun.tools.javac.code.Symbol.*;
 39 import com.sun.tools.javac.code.Type.*;
 40 import com.sun.tools.javac.main.Option.PkgInfo;
 41 import com.sun.tools.javac.resources.CompilerProperties.Errors;
 42 import com.sun.tools.javac.resources.CompilerProperties.Warnings;
 43 import com.sun.tools.javac.tree.*;
 44 import com.sun.tools.javac.tree.JCTree.*;
 45 import com.sun.tools.javac.util.*;
 46 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
 47 import com.sun.tools.javac.util.List;
 48 
 49 import static com.sun.tools.javac.code.Flags.*;
 50 import static com.sun.tools.javac.code.Kinds.Kind.*;
 51 
 52 /** This class enters symbols for all encountered definitions into
 53  *  the symbol table. The pass consists of high-level two phases,
 54  *  organized as follows:
 55  *
 56  *  <p>In the first phase, all class symbols are entered into their
 57  *  enclosing scope, descending recursively down the tree for classes
 58  *  which are members of other classes. The class symbols are given a
 59  *  TypeEnter object as completer.
 60  *
 61  *  <p>In the second phase classes are completed using
 62  *  TypeEnter.complete(). Completion might occur on demand, but
 63  *  any classes that are not completed that way will be eventually
 64  *  completed by processing the `uncompleted' queue. Completion
 65  *  entails determination of a class's parameters, supertype and
 66  *  interfaces, as well as entering all symbols defined in the
 67  *  class into its scope, with the exception of class symbols which
 68  *  have been entered in phase 1.
 69  *
 70  *  <p>Whereas the first phase is organized as a sweep through all
 71  *  compiled syntax trees, the second phase is on-demand. Members of a
 72  *  class are entered when the contents of a class are first
 73  *  accessed. This is accomplished by installing completer objects in
 74  *  class symbols for compiled classes which invoke the type-enter
 75  *  phase for the corresponding class tree.
 76  *
 77  *  <p>Classes migrate from one phase to the next via queues:
 78  *
 79  *  <pre>{@literal
 80  *  class enter -> (Enter.uncompleted)         --> type enter
 81  *              -> (Todo)                      --> attribute
 82  *                                              (only for toplevel classes)
 83  *  }</pre>
 84  *
 85  *  <p><b>This is NOT part of any supported API.
 86  *  If you write code that depends on this, you do so at your own risk.
 87  *  This code and its internal interfaces are subject to change or
 88  *  deletion without notice.</b>
 89  */
 90 public class Enter extends JCTree.Visitor {
 91     protected static final Context.Key<Enter> enterKey = new Context.Key<>();
 92 
 93     Annotate annotate;
 94     Log log;
 95     Symtab syms;
 96     Check chk;
 97     TreeMaker make;
 98     TypeEnter typeEnter;
 99     Types types;
100     Lint lint;
101     Names names;
102     JavaFileManager fileManager;
103     PkgInfo pkginfoOpt;
104     TypeEnvs typeEnvs;
105     Modules modules;
106     JCDiagnostic.Factory diags;
107 
108     private final Todo todo;
109 
110     public static Enter instance(Context context) {
111         Enter instance = context.get(enterKey);
112         if (instance == null)
113             instance = new Enter(context);
114         return instance;
115     }
116 
117     @SuppressWarnings("this-escape")
118     protected Enter(Context context) {
119         context.put(enterKey, this);
120 
121         log = Log.instance(context);
122         make = TreeMaker.instance(context);
123         syms = Symtab.instance(context);
124         chk = Check.instance(context);
125         typeEnter = TypeEnter.instance(context);
126         types = Types.instance(context);
127         annotate = Annotate.instance(context);
128         lint = Lint.instance(context);
129         names = Names.instance(context);
130         modules = Modules.instance(context);
131         diags = JCDiagnostic.Factory.instance(context);
132 
133         predefClassDef = make.ClassDef(
134             make.Modifiers(PUBLIC),
135             syms.predefClass.name,
136             List.nil(),
137             null,
138             List.nil(),
139             List.nil());
140         predefClassDef.sym = syms.predefClass;
141         todo = Todo.instance(context);
142         fileManager = context.get(JavaFileManager.class);
143 
144         Options options = Options.instance(context);
145         pkginfoOpt = PkgInfo.get(options);
146         typeEnvs = TypeEnvs.instance(context);
147     }
148 
149     /** Accessor for typeEnvs
150      */
151     public Env<AttrContext> getEnv(TypeSymbol sym) {
152         return typeEnvs.get(sym);
153     }
154 
155     public Iterable<Env<AttrContext>> getEnvs() {
156         return typeEnvs.values();
157     }
158 
159     public Env<AttrContext> getClassEnv(TypeSymbol sym) {
160         Env<AttrContext> localEnv = getEnv(sym);
161         if (localEnv == null) return null;
162         Env<AttrContext> lintEnv = localEnv;
163         while (lintEnv.info.lint == null)
164             lintEnv = lintEnv.next;
165         localEnv.info.lint = lintEnv.info.lint.augment(sym);
166         return localEnv;
167     }
168 
169     /** The queue of all classes that might still need to be completed;
170      *  saved and initialized by main().
171      */
172     ListBuffer<ClassSymbol> uncompleted;
173 
174     /** The queue of classes that should have typeEnter completer installed after
175      *  all the classes are discovered.
176      */
177     List<ClassSymbol> pendingCompleter = null;
178 
179     /** The queue of modules whose imports still need to be checked. */
180     ListBuffer<JCCompilationUnit> unfinishedModules = new ListBuffer<>();
181 
182     /** A dummy class to serve as enclClass for toplevel environments.
183      */
184     private JCClassDecl predefClassDef;
185 
186 /* ************************************************************************
187  * environment construction
188  *************************************************************************/
189 
190 
191     /** Create a fresh environment for class bodies.
192      *  This will create a fresh scope for local symbols of a class, referred
193      *  to by the environments info.scope field.
194      *  This scope will contain
195      *    - symbols for this and super
196      *    - symbols for any type parameters
197      *  In addition, it serves as an anchor for scopes of methods and initializers
198      *  which are nested in this scope via Scope.dup().
199      *  This scope should not be confused with the members scope of a class.
200      *
201      *  @param tree     The class definition.
202      *  @param env      The environment current outside of the class definition.
203      */
204     public Env<AttrContext> classEnv(JCClassDecl tree, Env<AttrContext> env) {
205         Env<AttrContext> localEnv =
206             env.dup(tree, env.info.dup(WriteableScope.create(tree.sym)));
207         localEnv.enclClass = tree;
208         localEnv.outer = env;
209         localEnv.info.isSelfCall = false;
210         localEnv.info.lint = null; // leave this to be filled in by Attr,
211                                    // when annotations have been processed
212         localEnv.info.isAnonymousDiamond = TreeInfo.isDiamond(env.tree);
213         return localEnv;
214     }
215 
216     /** Create a fresh environment for toplevels.
217      *  @param tree     The toplevel tree.
218      */
219     Env<AttrContext> topLevelEnv(JCCompilationUnit tree) {
220         Env<AttrContext> localEnv = new Env<>(tree, new AttrContext());
221         localEnv.toplevel = tree;
222         localEnv.enclClass = predefClassDef;
223         tree.toplevelScope = WriteableScope.create(tree.packge);
224         tree.namedImportScope = new NamedImportScope(tree.packge);
225         tree.starImportScope = new StarImportScope(tree.packge);
226         localEnv.info.scope = tree.toplevelScope;
227         localEnv.info.lint = lint;
228         return localEnv;
229     }
230 
231     public Env<AttrContext> getTopLevelEnv(JCCompilationUnit tree) {
232         Env<AttrContext> localEnv = new Env<>(tree, new AttrContext());
233         localEnv.toplevel = tree;
234         localEnv.enclClass = predefClassDef;
235         localEnv.info.scope = tree.toplevelScope;
236         localEnv.info.lint = lint;
237         return localEnv;
238     }
239 
240     /** The scope in which a member definition in environment env is to be entered
241      *  This is usually the environment's scope, except for class environments,
242      *  where the local scope is for type variables, and the this and super symbol
243      *  only, and members go into the class member scope.
244      */
245     WriteableScope enterScope(Env<AttrContext> env) {
246         return (env.tree.hasTag(JCTree.Tag.CLASSDEF))
247             ? ((JCClassDecl) env.tree).sym.members_field
248             : env.info.scope;
249     }
250 
251     /** Create a fresh environment for modules.
252      *
253      *  @param tree     The module definition.
254      *  @param env      The environment current outside of the module definition.
255      */
256     public Env<AttrContext> moduleEnv(JCModuleDecl tree, Env<AttrContext> env) {
257         Assert.checkNonNull(tree.sym);
258         Env<AttrContext> localEnv =
259             env.dup(tree, env.info.dup(WriteableScope.create(tree.sym)));
260         localEnv.enclClass = predefClassDef;
261         localEnv.outer = env;
262         localEnv.info.isSelfCall = false;
263         localEnv.info.lint = null; // leave this to be filled in by Attr,
264                                    // when annotations have been processed
265         return localEnv;
266     }
267 
268 
269 /* ************************************************************************
270  * Visitor methods for phase 1: class enter
271  *************************************************************************/
272 
273     /** Visitor argument: the current environment.
274      */
275     protected Env<AttrContext> env;
276 
277     /** Visitor result: the computed type.
278      */
279     Type result;
280 
281     /** Visitor method: enter all classes in given tree, catching any
282      *  completion failure exceptions. Return the tree's type.
283      *
284      *  @param tree    The tree to be visited.
285      *  @param env     The environment visitor argument.
286      */
287     Type classEnter(JCTree tree, Env<AttrContext> env) {
288         Env<AttrContext> prevEnv = this.env;
289         try {
290             this.env = env;
291             annotate.blockAnnotations();
292             tree.accept(this);
293             return result;
294         }  catch (CompletionFailure ex) {
295             return chk.completionError(tree.pos(), ex);
296         } finally {
297             annotate.unblockAnnotations();
298             this.env = prevEnv;
299         }
300     }
301 
302     /** Visitor method: enter classes of a list of trees, returning a list of types.
303      */
304     <T extends JCTree> List<Type> classEnter(List<T> trees, Env<AttrContext> env) {
305         ListBuffer<Type> ts = new ListBuffer<>();
306         for (List<T> l = trees; l.nonEmpty(); l = l.tail) {
307             Type t = classEnter(l.head, env);
308             if (t != null)
309                 ts.append(t);
310         }
311         return ts.toList();
312     }
313 
314     @Override
315     public void visitTopLevel(JCCompilationUnit tree) {
316         JavaFileObject prev = log.useSource(tree.sourcefile);
317         boolean addEnv = false;
318         boolean isPkgInfo = tree.sourcefile.isNameCompatible("package-info",
319                                                              JavaFileObject.Kind.SOURCE);
320         if (TreeInfo.isModuleInfo(tree)) {
321             JCPackageDecl pd = tree.getPackage();
322             if (pd != null) {
323                 log.error(pd.pos(), Errors.NoPkgInModuleInfoJava);
324             }
325             tree.packge = syms.rootPackage;
326             Env<AttrContext> topEnv = topLevelEnv(tree);
327             classEnter(tree.defs, topEnv);
328             tree.modle.usesProvidesCompleter = modules.getUsesProvidesCompleter();
329         } else {
330             JCPackageDecl pd = tree.getPackage();
331             if (pd != null) {
332                 tree.packge = pd.packge = syms.enterPackage(tree.modle, TreeInfo.fullName(pd.pid));
333                 setPackageSymbols.scan(pd);
334                 if (   pd.annotations.nonEmpty()
335                     || pkginfoOpt == PkgInfo.ALWAYS
336                     || tree.docComments != null) {
337                     if (isPkgInfo) {
338                         addEnv = true;
339                     } else if (pd.annotations.nonEmpty()) {
340                         log.error(pd.annotations.head.pos(),
341                                   Errors.PkgAnnotationsSbInPackageInfoJava);
342                     }
343                 }
344             } else {
345                 tree.packge = tree.modle.unnamedPackage;
346             }
347 
348             Map<Name, PackageSymbol> visiblePackages = tree.modle.visiblePackages;
349             Optional<ModuleSymbol> dependencyWithPackage =
350                 syms.listPackageModules(tree.packge.fullname)
351                     .stream()
352                     .filter(m -> m != tree.modle)
353                     .filter(cand -> visiblePackages.get(tree.packge.fullname) == syms.getPackage(cand, tree.packge.fullname))
354                     .findAny();
355 
356             if (dependencyWithPackage.isPresent()) {
357                 log.error(pd, Errors.PackageInOtherModule(dependencyWithPackage.get()));
358             }
359 
360             tree.packge.complete(); // Find all classes in package.
361 
362             Env<AttrContext> topEnv = topLevelEnv(tree);
363             Env<AttrContext> packageEnv = null;
364 
365             // Save environment of package-info.java file.
366             if (isPkgInfo) {
367                 packageEnv = topEnv.dup(pd != null ? pd : tree);
368 
369                 Env<AttrContext> env0 = typeEnvs.get(tree.packge);
370                 if (env0 != null) {
371                     JCCompilationUnit tree0 = env0.toplevel;
372                     if (!fileManager.isSameFile(tree.sourcefile, tree0.sourcefile)) {
373                         log.warning(pd != null ? pd.pid.pos() : null,
374                                     Warnings.PkgInfoAlreadySeen(tree.packge));
375                     }
376                 }
377                 typeEnvs.put(tree.packge, packageEnv);
378 
379                 for (Symbol q = tree.packge; q != null && q.kind == PCK; q = q.owner)
380                     q.flags_field |= EXISTS;
381 
382                 Name name = names.package_info;
383                 ClassSymbol c = syms.enterClass(tree.modle, name, tree.packge);
384                 c.flatname = names.fromString(tree.packge + "." + name);
385                 c.classfile = c.sourcefile = tree.sourcefile;
386                 c.completer = Completer.NULL_COMPLETER;
387                 c.members_field = WriteableScope.create(c);
388                 tree.packge.package_info = c;
389                 tree.packge.sourcefile = tree.sourcefile;
390             }
391             classEnter(tree.defs, topEnv);
392             if (addEnv) {
393                 todo.append(packageEnv);
394             }
395         }
396         log.useSource(prev);
397         result = null;
398     }
399         //where:
400         //set package Symbols to the package expression:
401         private final TreeScanner setPackageSymbols = new TreeScanner() {
402             Symbol currentPackage;
403 
404             @Override
405             public void visitIdent(JCIdent tree) {
406                 tree.sym = currentPackage;
407                 tree.type = currentPackage.type;
408             }
409 
410             @Override
411             public void visitSelect(JCFieldAccess tree) {
412                 tree.sym = currentPackage;
413                 tree.type = currentPackage.type;
414                 currentPackage = currentPackage.owner;
415                 super.visitSelect(tree);
416             }
417 
418             @Override
419             public void visitPackageDef(JCPackageDecl tree) {
420                 currentPackage = tree.packge;
421                 scan(tree.pid);
422             }
423         };
424 
425     @Override
426     public void visitClassDef(JCClassDecl tree) {
427         Symbol owner = env.info.scope.owner;
428         WriteableScope enclScope = enterScope(env);
429         ClassSymbol c;
430         if (owner.kind == PCK) {
431             // We are seeing a toplevel class.
432             PackageSymbol packge = (PackageSymbol)owner;
433             for (Symbol q = packge; q != null && q.kind == PCK; q = q.owner)
434                 q.flags_field |= EXISTS;
435             c = syms.enterClass(env.toplevel.modle, tree.name, packge);
436             packge.members().enterIfAbsent(c);
437             if ((tree.mods.flags & PUBLIC) != 0 && !classNameMatchesFileName(c, env)) {
438                 KindName topElement = KindName.CLASS;
439                 if ((tree.mods.flags & ENUM) != 0) {
440                     topElement = KindName.ENUM;
441                 } else if ((tree.mods.flags & INTERFACE) != 0) {
442                     topElement = KindName.INTERFACE;
443                 }
444                 log.error(tree.pos(),
445                           Errors.ClassPublicShouldBeInFile(topElement, tree.name));
446             }
447             if ((tree.mods.flags & UNNAMED_CLASS) != 0) {
448                 syms.removeClass(env.toplevel.modle, tree.name);
449             }
450         } else {
451             if (!tree.name.isEmpty() &&
452                 !chk.checkUniqueClassName(tree.pos(), tree.name, enclScope)) {
453                 result = null;
454                 return;
455             }
456             if (owner.kind == TYP) {
457                 // We are seeing a member class.
458                 c = syms.enterClass(env.toplevel.modle, tree.name, (TypeSymbol)owner);
459                 if (c.owner != owner) {
460                     if (c.name != tree.name) {
461                         log.error(tree.pos(), Errors.SameBinaryName(c.name, tree.name));
462                         result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);
463                         tree.sym = (ClassSymbol)result.tsym;
464                         return;
465                     }
466                     //anonymous class loaded from a classfile may be recreated from source (see below)
467                     //if this class is a member of such an anonymous class, fix the owner:
468                     Assert.check(owner.owner.kind != TYP, owner::toString);
469                     Assert.check(c.owner.kind == TYP, () -> c.owner.toString());
470                     ClassSymbol cowner = (ClassSymbol) c.owner;
471                     if (cowner.members_field != null) {
472                         cowner.members_field.remove(c);
473                     }
474                     c.owner = owner;
475                 }
476                 if ((owner.flags_field & INTERFACE) != 0) {
477                     tree.mods.flags |= PUBLIC | STATIC;
478                 }
479             } else {
480                 // We are seeing a local class.
481                 c = syms.defineClass(tree.name, owner);
482                 c.flatname = chk.localClassName(c);
483                 if (!c.name.isEmpty())
484                     chk.checkTransparentClass(tree.pos(), c, env.info.scope);
485             }
486         }
487         tree.sym = c;
488 
489         // Enter class into `compiled' table and enclosing scope.
490         if (chk.getCompiled(c) != null) {
491             duplicateClass(tree.pos(), c);
492             result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);
493             tree.sym = (ClassSymbol)result.tsym;
494             return;
495         }
496         chk.putCompiled(c);
497         enclScope.enter(c);
498 
499         // Set up an environment for class block and store in `typeEnvs'
500         // table, to be retrieved later in memberEnter and attribution.
501         Env<AttrContext> localEnv = classEnv(tree, env);
502         typeEnvs.put(c, localEnv);
503 
504         // Fill out class fields.
505         c.completer = Completer.NULL_COMPLETER; // do not allow the initial completer linger on.
506         c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree) | FROM_SOURCE;
507         c.classfile = c.sourcefile = env.toplevel.sourcefile;
508         c.members_field = WriteableScope.create(c);
509         c.isPermittedExplicit = tree.permitting.nonEmpty();
510         c.clearAnnotationMetadata();
511 
512         ClassType ct = (ClassType)c.type;
513         if (owner.kind != PCK && (c.flags_field & STATIC) == 0) {
514             // We are seeing a local or inner class.
515             // Set outer_field of this class to closest enclosing class
516             // which contains this class in a non-static context
517             // (its "enclosing instance class"), provided such a class exists.
518             Symbol owner1 = owner;
519             while (owner1.kind.matches(KindSelector.VAL_MTH) &&
520                    (owner1.flags_field & STATIC) == 0) {
521                 owner1 = owner1.owner;
522             }
523             if (owner1.kind == TYP) {
524                 ct.setEnclosingType(owner1.type);
525             }
526         }
527 
528         // Enter type parameters.
529         ct.typarams_field = classEnter(tree.typarams, localEnv);
530         ct.allparams_field = null;
531 
532         // schedule installation of further completer for this type.
533         if (pendingCompleter != null) {
534             pendingCompleter = pendingCompleter.prepend(c);
535         } else {
536             c.completer = typeEnter;
537         }
538 
539         // Add non-local class to uncompleted, to make sure it will be
540         // completed later.
541         if (!c.isDirectlyOrIndirectlyLocal() && uncompleted != null) uncompleted.append(c);
542 //      System.err.println("entering " + c.fullname + " in " + c.owner);//DEBUG
543 
544         // Recursively enter all member classes.
545         classEnter(tree.defs, localEnv);
546 
547 //        Assert.checkNonNull(c.modle, c.sourcefile.toString());
548 
549         result = c.type;
550     }
551     //where
552         /** Does class have the same name as the file it appears in?
553          */
554         private static boolean classNameMatchesFileName(ClassSymbol c,
555                                                         Env<AttrContext> env) {
556             return env.toplevel.sourcefile.isNameCompatible(c.name.toString(),
557                                                             JavaFileObject.Kind.SOURCE);
558         }
559 
560     /** Complain about a duplicate class. */
561     protected void duplicateClass(DiagnosticPosition pos, ClassSymbol c) {
562         log.error(pos, Errors.DuplicateClass(c.fullname));
563     }
564 
565     /** Class enter visitor method for type parameters.
566      *  Enter a symbol for type parameter in local scope, after checking that it
567      *  is unique.
568      */
569     @Override
570     public void visitTypeParameter(JCTypeParameter tree) {
571         TypeVar a = (tree.type != null)
572             ? (TypeVar)tree.type
573             : new TypeVar(tree.name, env.info.scope.owner, syms.botType);
574         tree.type = a;
575         if (chk.checkUnique(tree.pos(), a.tsym, env.info.scope)) {
576             env.info.scope.enter(a.tsym);
577         }
578         result = a;
579     }
580 
581     @Override
582     public void visitModuleDef(JCModuleDecl tree) {
583         Env<AttrContext> moduleEnv = moduleEnv(tree, env);
584         typeEnvs.put(tree.sym, moduleEnv);
585         if (modules.isInModuleGraph(tree.sym)) {
586             todo.append(moduleEnv);
587         }
588     }
589 
590     /** Default class enter visitor method: do nothing.
591      */
592     @Override
593     public void visitTree(JCTree tree) {
594         result = null;
595     }
596 
597     /** Main method: enter all classes in a list of toplevel trees.
598      *  @param trees      The list of trees to be processed.
599      */
600     public void main(List<JCCompilationUnit> trees) {
601         complete(trees, null);
602     }
603 
604     /** Main method: enter classes from the list of toplevel trees, possibly
605      *  skipping TypeEnter for all but 'c' by placing them on the uncompleted
606      *  list.
607      *  @param trees      The list of trees to be processed.
608      *  @param c          The class symbol to be processed or null to process all.
609      */
610     public void complete(List<JCCompilationUnit> trees, ClassSymbol c) {
611         annotate.blockAnnotations();
612         ListBuffer<ClassSymbol> prevUncompleted = uncompleted;
613         if (typeEnter.completionEnabled) uncompleted = new ListBuffer<>();
614 
615         try {
616             List<ClassSymbol> prevPendingCompleter = pendingCompleter;
617             try {
618                 pendingCompleter = List.nil();
619                 // enter all classes, and construct uncompleted list
620                 classEnter(trees, null);
621                 // install further completer for classes recognized by the above task:
622                 for (ClassSymbol sym : pendingCompleter) {
623                     sym.completer = typeEnter;
624                 }
625             } finally {
626                 pendingCompleter = prevPendingCompleter;
627             }
628 
629             // complete all uncompleted classes in memberEnter
630             if (typeEnter.completionEnabled) {
631                 while (uncompleted.nonEmpty()) {
632                     ClassSymbol clazz = uncompleted.next();
633                     if (c == null || c == clazz || prevUncompleted == null)
634                         clazz.complete();
635                     else
636                         // defer
637                         prevUncompleted.append(clazz);
638                 }
639 
640                 if (!modules.modulesInitialized()) {
641                     for (JCCompilationUnit cut : trees) {
642                         if (cut.getModuleDecl() != null) {
643                             unfinishedModules.append(cut);
644                         } else {
645                             typeEnter.ensureImportsChecked(List.of(cut));
646                         }
647                     }
648                 } else {
649                     typeEnter.ensureImportsChecked(unfinishedModules.toList());
650                     unfinishedModules.clear();
651                     typeEnter.ensureImportsChecked(trees);
652                 }
653             }
654         } finally {
655             uncompleted = prevUncompleted;
656             annotate.unblockAnnotations();
657         }
658     }
659 
660     public void newRound() {
661         typeEnvs.clear();
662     }
663 
664     public void unenter(JCCompilationUnit topLevel, JCTree tree) {
665         new UnenterScanner(topLevel.modle).scan(tree);
666     }
667         class UnenterScanner extends TreeScanner {
668             private final ModuleSymbol msym;
669 
670             public UnenterScanner(ModuleSymbol msym) {
671                 this.msym = msym;
672             }
673 
674             @Override
675             public void visitClassDef(JCClassDecl tree) {
676                 ClassSymbol csym = tree.sym;
677                 //if something went wrong during method applicability check
678                 //it is possible that nested expressions inside argument expression
679                 //are left unchecked - in such cases there's nothing to clean up.
680                 if (csym == null) return;
681                 typeEnvs.remove(csym);
682                 chk.removeCompiled(csym);
683                 chk.clearLocalClassNameIndexes(csym);
684                 syms.removeClass(msym, csym.flatname);
685                 super.visitClassDef(tree);
686             }
687         }
688 }