1 /*
   2  * Copyright (c) 1999, 2022, 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.*;
  29 import java.util.function.BiConsumer;
  30 import java.util.function.Predicate;
  31 import java.util.function.Supplier;
  32 
  33 import javax.lang.model.element.ElementKind;
  34 import javax.lang.model.element.NestingKind;
  35 import javax.tools.JavaFileManager;
  36 
  37 import com.sun.source.tree.CaseTree;
  38 import com.sun.tools.javac.code.*;
  39 import com.sun.tools.javac.code.Attribute.Compound;
  40 import com.sun.tools.javac.code.Directive.ExportsDirective;
  41 import com.sun.tools.javac.code.Directive.RequiresDirective;
  42 import com.sun.tools.javac.code.Source.Feature;
  43 import com.sun.tools.javac.comp.Annotate.AnnotationTypeMetadata;
  44 import com.sun.tools.javac.jvm.*;
  45 import com.sun.tools.javac.resources.CompilerProperties.Errors;
  46 import com.sun.tools.javac.resources.CompilerProperties.Fragments;
  47 import com.sun.tools.javac.resources.CompilerProperties.Warnings;
  48 import com.sun.tools.javac.tree.*;
  49 import com.sun.tools.javac.util.*;
  50 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticFlag;
  51 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
  52 import com.sun.tools.javac.util.JCDiagnostic.Error;
  53 import com.sun.tools.javac.util.JCDiagnostic.Fragment;
  54 import com.sun.tools.javac.util.JCDiagnostic.Warning;
  55 import com.sun.tools.javac.util.List;
  56 
  57 import com.sun.tools.javac.code.Lint;
  58 import com.sun.tools.javac.code.Lint.LintCategory;
  59 import com.sun.tools.javac.code.Scope.WriteableScope;
  60 import com.sun.tools.javac.code.Type.*;
  61 import com.sun.tools.javac.code.Symbol.*;
  62 import com.sun.tools.javac.comp.DeferredAttr.DeferredAttrContext;
  63 import com.sun.tools.javac.tree.JCTree.*;
  64 
  65 import static com.sun.tools.javac.code.Flags.*;
  66 import static com.sun.tools.javac.code.Flags.ANNOTATION;
  67 import static com.sun.tools.javac.code.Flags.SYNCHRONIZED;
  68 import static com.sun.tools.javac.code.Kinds.*;
  69 import static com.sun.tools.javac.code.Kinds.Kind.*;
  70 import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
  71 import static com.sun.tools.javac.code.TypeTag.*;
  72 import static com.sun.tools.javac.code.TypeTag.WILDCARD;
  73 
  74 import static com.sun.tools.javac.tree.JCTree.Tag.*;
  75 import javax.lang.model.element.Element;
  76 import javax.lang.model.element.ExecutableElement;
  77 import javax.lang.model.element.TypeElement;
  78 import javax.lang.model.type.DeclaredType;
  79 import javax.lang.model.type.TypeMirror;
  80 import javax.lang.model.util.ElementFilter;
  81 import javax.lang.model.util.ElementKindVisitor14;
  82 
  83 /** Type checking helper class for the attribution phase.
  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 Check {
  91     protected static final Context.Key<Check> checkKey = new Context.Key<>();
  92 
  93     private final Names names;
  94     private final Log log;
  95     private final Resolve rs;
  96     private final Symtab syms;
  97     private final Enter enter;
  98     private final DeferredAttr deferredAttr;
  99     private final Infer infer;
 100     private final Types types;
 101     private final TypeAnnotations typeAnnotations;
 102     private final JCDiagnostic.Factory diags;
 103     private final JavaFileManager fileManager;
 104     private final Source source;
 105     private final Target target;
 106     private final Profile profile;
 107     private final Preview preview;
 108     private final boolean warnOnAnyAccessToMembers;
 109 
 110     // The set of lint options currently in effect. It is initialized
 111     // from the context, and then is set/reset as needed by Attr as it
 112     // visits all the various parts of the trees during attribution.
 113     private Lint lint;
 114 
 115     // The method being analyzed in Attr - it is set/reset as needed by
 116     // Attr as it visits new method declarations.
 117     private MethodSymbol method;
 118 
 119     public static Check instance(Context context) {
 120         Check instance = context.get(checkKey);
 121         if (instance == null)
 122             instance = new Check(context);
 123         return instance;
 124     }
 125 
 126     protected Check(Context context) {
 127         context.put(checkKey, this);
 128 
 129         names = Names.instance(context);
 130         log = Log.instance(context);
 131         rs = Resolve.instance(context);
 132         syms = Symtab.instance(context);
 133         enter = Enter.instance(context);
 134         deferredAttr = DeferredAttr.instance(context);
 135         infer = Infer.instance(context);
 136         types = Types.instance(context);
 137         typeAnnotations = TypeAnnotations.instance(context);
 138         diags = JCDiagnostic.Factory.instance(context);
 139         Options options = Options.instance(context);
 140         lint = Lint.instance(context);
 141         fileManager = context.get(JavaFileManager.class);
 142 
 143         source = Source.instance(context);
 144         target = Target.instance(context);
 145         warnOnAnyAccessToMembers = options.isSet("warnOnAccessToMembers");
 146         Target target = Target.instance(context);
 147         syntheticNameChar = target.syntheticNameChar();
 148 
 149         profile = Profile.instance(context);
 150         preview = Preview.instance(context);
 151 
 152         boolean verboseDeprecated = lint.isEnabled(LintCategory.DEPRECATION);
 153         boolean verboseRemoval = lint.isEnabled(LintCategory.REMOVAL);
 154         boolean verboseUnchecked = lint.isEnabled(LintCategory.UNCHECKED);
 155         boolean enforceMandatoryWarnings = true;
 156 
 157         deprecationHandler = new MandatoryWarningHandler(log, null, verboseDeprecated,
 158                 enforceMandatoryWarnings, "deprecated", LintCategory.DEPRECATION);
 159         removalHandler = new MandatoryWarningHandler(log, null, verboseRemoval,
 160                 enforceMandatoryWarnings, "removal", LintCategory.REMOVAL);
 161         uncheckedHandler = new MandatoryWarningHandler(log, null, verboseUnchecked,
 162                 enforceMandatoryWarnings, "unchecked", LintCategory.UNCHECKED);
 163         sunApiHandler = new MandatoryWarningHandler(log, null, false,
 164                 enforceMandatoryWarnings, "sunapi", null);
 165 
 166         deferredLintHandler = DeferredLintHandler.instance(context);
 167 
 168         allowModules = Feature.MODULES.allowedInSource(source);
 169         allowRecords = Feature.RECORDS.allowedInSource(source);
 170         allowSealed = Feature.SEALED_CLASSES.allowedInSource(source);
 171     }
 172 
 173     /** Character for synthetic names
 174      */
 175     char syntheticNameChar;
 176 
 177     /** A table mapping flat names of all compiled classes for each module in this run
 178      *  to their symbols; maintained from outside.
 179      */
 180     private Map<Pair<ModuleSymbol, Name>,ClassSymbol> compiled = new HashMap<>();
 181 
 182     /** A handler for messages about deprecated usage.
 183      */
 184     private MandatoryWarningHandler deprecationHandler;
 185 
 186     /** A handler for messages about deprecated-for-removal usage.
 187      */
 188     private MandatoryWarningHandler removalHandler;
 189 
 190     /** A handler for messages about unchecked or unsafe usage.
 191      */
 192     private MandatoryWarningHandler uncheckedHandler;
 193 
 194     /** A handler for messages about using proprietary API.
 195      */
 196     private MandatoryWarningHandler sunApiHandler;
 197 
 198     /** A handler for deferred lint warnings.
 199      */
 200     private DeferredLintHandler deferredLintHandler;
 201 
 202     /** Are modules allowed
 203      */
 204     private final boolean allowModules;
 205 
 206     /** Are records allowed
 207      */
 208     private final boolean allowRecords;
 209 
 210     /** Are sealed classes allowed
 211      */
 212     private final boolean allowSealed;
 213 
 214 /* *************************************************************************
 215  * Errors and Warnings
 216  **************************************************************************/
 217 
 218     Lint setLint(Lint newLint) {
 219         Lint prev = lint;
 220         lint = newLint;
 221         return prev;
 222     }
 223 
 224     MethodSymbol setMethod(MethodSymbol newMethod) {
 225         MethodSymbol prev = method;
 226         method = newMethod;
 227         return prev;
 228     }
 229 
 230     /** Warn about deprecated symbol.
 231      *  @param pos        Position to be used for error reporting.
 232      *  @param sym        The deprecated symbol.
 233      */
 234     void warnDeprecated(DiagnosticPosition pos, Symbol sym) {
 235         if (sym.isDeprecatedForRemoval()) {
 236             if (!lint.isSuppressed(LintCategory.REMOVAL)) {
 237                 if (sym.kind == MDL) {
 238                     removalHandler.report(pos, Warnings.HasBeenDeprecatedForRemovalModule(sym));
 239                 } else {
 240                     removalHandler.report(pos, Warnings.HasBeenDeprecatedForRemoval(sym, sym.location()));
 241                 }
 242             }
 243         } else if (!lint.isSuppressed(LintCategory.DEPRECATION)) {
 244             if (sym.kind == MDL) {
 245                 deprecationHandler.report(pos, Warnings.HasBeenDeprecatedModule(sym));
 246             } else {
 247                 deprecationHandler.report(pos, Warnings.HasBeenDeprecated(sym, sym.location()));
 248             }
 249         }
 250     }
 251 
 252     /** Log a preview warning.
 253      *  @param pos        Position to be used for error reporting.
 254      *  @param msg        A Warning describing the problem.
 255      */
 256     public void warnPreviewAPI(DiagnosticPosition pos, Warning warnKey) {
 257         if (!lint.isSuppressed(LintCategory.PREVIEW))
 258             preview.reportPreviewWarning(pos, warnKey);
 259     }
 260 
 261     /** Log a preview warning.
 262      *  @param pos        Position to be used for error reporting.
 263      *  @param msg        A Warning describing the problem.
 264      */
 265     public void warnDeclaredUsingPreview(DiagnosticPosition pos, Symbol sym) {
 266         if (!lint.isSuppressed(LintCategory.PREVIEW))
 267             preview.reportPreviewWarning(pos, Warnings.DeclaredUsingPreview(kindName(sym), sym));
 268     }
 269 
 270     /** Warn about unchecked operation.
 271      *  @param pos        Position to be used for error reporting.
 272      *  @param msg        A string describing the problem.
 273      */
 274     public void warnUnchecked(DiagnosticPosition pos, Warning warnKey) {
 275         if (!lint.isSuppressed(LintCategory.UNCHECKED))
 276             uncheckedHandler.report(pos, warnKey);
 277     }
 278 
 279     /** Warn about unsafe vararg method decl.
 280      *  @param pos        Position to be used for error reporting.
 281      */
 282     void warnUnsafeVararg(DiagnosticPosition pos, Warning warnKey) {
 283         if (lint.isEnabled(LintCategory.VARARGS))
 284             log.warning(LintCategory.VARARGS, pos, warnKey);
 285     }
 286 
 287     public void warnStatic(DiagnosticPosition pos, Warning warnKey) {
 288         if (lint.isEnabled(LintCategory.STATIC))
 289             log.warning(LintCategory.STATIC, pos, warnKey);
 290     }
 291 
 292     /** Warn about division by integer constant zero.
 293      *  @param pos        Position to be used for error reporting.
 294      */
 295     void warnDivZero(DiagnosticPosition pos) {
 296         if (lint.isEnabled(LintCategory.DIVZERO))
 297             log.warning(LintCategory.DIVZERO, pos, Warnings.DivZero);
 298     }
 299 
 300     /**
 301      * Report any deferred diagnostics.
 302      */
 303     public void reportDeferredDiagnostics() {
 304         deprecationHandler.reportDeferredDiagnostic();
 305         removalHandler.reportDeferredDiagnostic();
 306         uncheckedHandler.reportDeferredDiagnostic();
 307         sunApiHandler.reportDeferredDiagnostic();
 308     }
 309 
 310 
 311     /** Report a failure to complete a class.
 312      *  @param pos        Position to be used for error reporting.
 313      *  @param ex         The failure to report.
 314      */
 315     public Type completionError(DiagnosticPosition pos, CompletionFailure ex) {
 316         log.error(JCDiagnostic.DiagnosticFlag.NON_DEFERRABLE, pos, Errors.CantAccess(ex.sym, ex.getDetailValue()));
 317         return syms.errType;
 318     }
 319 
 320     /** Report an error that wrong type tag was found.
 321      *  @param pos        Position to be used for error reporting.
 322      *  @param required   An internationalized string describing the type tag
 323      *                    required.
 324      *  @param found      The type that was found.
 325      */
 326     Type typeTagError(DiagnosticPosition pos, JCDiagnostic required, Object found) {
 327         // this error used to be raised by the parser,
 328         // but has been delayed to this point:
 329         if (found instanceof Type type && type.hasTag(VOID)) {
 330             log.error(pos, Errors.IllegalStartOfType);
 331             return syms.errType;
 332         }
 333         log.error(pos, Errors.TypeFoundReq(found, required));
 334         return types.createErrorType(found instanceof Type type ? type : syms.errType);
 335     }
 336 
 337     /** Report an error that symbol cannot be referenced before super
 338      *  has been called.
 339      *  @param pos        Position to be used for error reporting.
 340      *  @param sym        The referenced symbol.
 341      */
 342     void earlyRefError(DiagnosticPosition pos, Symbol sym) {
 343         log.error(pos, Errors.CantRefBeforeCtorCalled(sym));
 344     }
 345 
 346     /** Report duplicate declaration error.
 347      */
 348     void duplicateError(DiagnosticPosition pos, Symbol sym) {
 349         if (!sym.type.isErroneous()) {
 350             Symbol location = sym.location();
 351             if (location.kind == MTH &&
 352                     ((MethodSymbol)location).isStaticOrInstanceInit()) {
 353                 log.error(pos,
 354                           Errors.AlreadyDefinedInClinit(kindName(sym),
 355                                                         sym,
 356                                                         kindName(sym.location()),
 357                                                         kindName(sym.location().enclClass()),
 358                                                         sym.location().enclClass()));
 359             } else {
 360                 /* dont error if this is a duplicated parameter of a generated canonical constructor
 361                  * as we should have issued an error for the duplicated fields
 362                  */
 363                 if (location.kind != MTH ||
 364                         ((sym.owner.flags_field & GENERATEDCONSTR) == 0) ||
 365                         ((sym.owner.flags_field & RECORD) == 0)) {
 366                     log.error(pos,
 367                             Errors.AlreadyDefined(kindName(sym),
 368                                     sym,
 369                                     kindName(sym.location()),
 370                                     sym.location()));
 371                 }
 372             }
 373         }
 374     }
 375 
 376     /** Report array/varargs duplicate declaration
 377      */
 378     void varargsDuplicateError(DiagnosticPosition pos, Symbol sym1, Symbol sym2) {
 379         if (!sym1.type.isErroneous() && !sym2.type.isErroneous()) {
 380             log.error(pos, Errors.ArrayAndVarargs(sym1, sym2, sym2.location()));
 381         }
 382     }
 383 
 384 /* ************************************************************************
 385  * duplicate declaration checking
 386  *************************************************************************/
 387 
 388     /** Check that variable does not hide variable with same name in
 389      *  immediately enclosing local scope.
 390      *  @param pos           Position for error reporting.
 391      *  @param v             The symbol.
 392      *  @param s             The scope.
 393      */
 394     void checkTransparentVar(DiagnosticPosition pos, VarSymbol v, Scope s) {
 395         for (Symbol sym : s.getSymbolsByName(v.name)) {
 396             if (sym.owner != v.owner) break;
 397             if (sym.kind == VAR &&
 398                 sym.owner.kind.matches(KindSelector.VAL_MTH) &&
 399                 v.name != names.error) {
 400                 duplicateError(pos, sym);
 401                 return;
 402             }
 403         }
 404     }
 405 
 406     /** Check that a class or interface does not hide a class or
 407      *  interface with same name in immediately enclosing local scope.
 408      *  @param pos           Position for error reporting.
 409      *  @param c             The symbol.
 410      *  @param s             The scope.
 411      */
 412     void checkTransparentClass(DiagnosticPosition pos, ClassSymbol c, Scope s) {
 413         for (Symbol sym : s.getSymbolsByName(c.name)) {
 414             if (sym.owner != c.owner) break;
 415             if (sym.kind == TYP && !sym.type.hasTag(TYPEVAR) &&
 416                 sym.owner.kind.matches(KindSelector.VAL_MTH) &&
 417                 c.name != names.error) {
 418                 duplicateError(pos, sym);
 419                 return;
 420             }
 421         }
 422     }
 423 
 424     /** Check that class does not have the same name as one of
 425      *  its enclosing classes, or as a class defined in its enclosing scope.
 426      *  return true if class is unique in its enclosing scope.
 427      *  @param pos           Position for error reporting.
 428      *  @param name          The class name.
 429      *  @param s             The enclosing scope.
 430      */
 431     boolean checkUniqueClassName(DiagnosticPosition pos, Name name, Scope s) {
 432         for (Symbol sym : s.getSymbolsByName(name, NON_RECURSIVE)) {
 433             if (sym.kind == TYP && sym.name != names.error) {
 434                 duplicateError(pos, sym);
 435                 return false;
 436             }
 437         }
 438         for (Symbol sym = s.owner; sym != null; sym = sym.owner) {
 439             if (sym.kind == TYP && sym.name == name && sym.name != names.error) {
 440                 duplicateError(pos, sym);
 441                 return true;
 442             }
 443         }
 444         return true;
 445     }
 446 
 447 /* *************************************************************************
 448  * Class name generation
 449  **************************************************************************/
 450 
 451 
 452     private Map<Pair<Name, Name>, Integer> localClassNameIndexes = new HashMap<>();
 453 
 454     /** Return name of local class.
 455      *  This is of the form   {@code <enclClass> $ n <classname> }
 456      *  where
 457      *    enclClass is the flat name of the enclosing class,
 458      *    classname is the simple name of the local class
 459      */
 460     public Name localClassName(ClassSymbol c) {
 461         Name enclFlatname = c.owner.enclClass().flatname;
 462         String enclFlatnameStr = enclFlatname.toString();
 463         Pair<Name, Name> key = new Pair<>(enclFlatname, c.name);
 464         Integer index = localClassNameIndexes.get(key);
 465         for (int i = (index == null) ? 1 : index; ; i++) {
 466             Name flatname = names.fromString(enclFlatnameStr
 467                     + syntheticNameChar + i + c.name);
 468             if (getCompiled(c.packge().modle, flatname) == null) {
 469                 localClassNameIndexes.put(key, i + 1);
 470                 return flatname;
 471             }
 472         }
 473     }
 474 
 475     public void clearLocalClassNameIndexes(ClassSymbol c) {
 476         if (c.owner != null && c.owner.kind != NIL) {
 477             localClassNameIndexes.remove(new Pair<>(
 478                     c.owner.enclClass().flatname, c.name));
 479         }
 480     }
 481 
 482     public void newRound() {
 483         compiled.clear();
 484         localClassNameIndexes.clear();
 485     }
 486 
 487     public void clear() {
 488         deprecationHandler.clear();
 489         removalHandler.clear();
 490         uncheckedHandler.clear();
 491         sunApiHandler.clear();
 492     }
 493 
 494     public void putCompiled(ClassSymbol csym) {
 495         compiled.put(Pair.of(csym.packge().modle, csym.flatname), csym);
 496     }
 497 
 498     public ClassSymbol getCompiled(ClassSymbol csym) {
 499         return compiled.get(Pair.of(csym.packge().modle, csym.flatname));
 500     }
 501 
 502     public ClassSymbol getCompiled(ModuleSymbol msym, Name flatname) {
 503         return compiled.get(Pair.of(msym, flatname));
 504     }
 505 
 506     public void removeCompiled(ClassSymbol csym) {
 507         compiled.remove(Pair.of(csym.packge().modle, csym.flatname));
 508     }
 509 
 510     /* *************************************************************************
 511  * Type Checking
 512  **************************************************************************/
 513 
 514     /**
 515      * A check context is an object that can be used to perform compatibility
 516      * checks - depending on the check context, meaning of 'compatibility' might
 517      * vary significantly.
 518      */
 519     public interface CheckContext {
 520         /**
 521          * Is type 'found' compatible with type 'req' in given context
 522          */
 523         boolean compatible(Type found, Type req, Warner warn);
 524         /**
 525          * Report a check error
 526          */
 527         void report(DiagnosticPosition pos, JCDiagnostic details);
 528         /**
 529          * Obtain a warner for this check context
 530          */
 531         public Warner checkWarner(DiagnosticPosition pos, Type found, Type req);
 532 
 533         public InferenceContext inferenceContext();
 534 
 535         public DeferredAttr.DeferredAttrContext deferredAttrContext();
 536     }
 537 
 538     /**
 539      * This class represent a check context that is nested within another check
 540      * context - useful to check sub-expressions. The default behavior simply
 541      * redirects all method calls to the enclosing check context leveraging
 542      * the forwarding pattern.
 543      */
 544     static class NestedCheckContext implements CheckContext {
 545         CheckContext enclosingContext;
 546 
 547         NestedCheckContext(CheckContext enclosingContext) {
 548             this.enclosingContext = enclosingContext;
 549         }
 550 
 551         public boolean compatible(Type found, Type req, Warner warn) {
 552             return enclosingContext.compatible(found, req, warn);
 553         }
 554 
 555         public void report(DiagnosticPosition pos, JCDiagnostic details) {
 556             enclosingContext.report(pos, details);
 557         }
 558 
 559         public Warner checkWarner(DiagnosticPosition pos, Type found, Type req) {
 560             return enclosingContext.checkWarner(pos, found, req);
 561         }
 562 
 563         public InferenceContext inferenceContext() {
 564             return enclosingContext.inferenceContext();
 565         }
 566 
 567         public DeferredAttrContext deferredAttrContext() {
 568             return enclosingContext.deferredAttrContext();
 569         }
 570     }
 571 
 572     /**
 573      * Check context to be used when evaluating assignment/return statements
 574      */
 575     CheckContext basicHandler = new CheckContext() {
 576         public void report(DiagnosticPosition pos, JCDiagnostic details) {
 577             log.error(pos, Errors.ProbFoundReq(details));
 578         }
 579         public boolean compatible(Type found, Type req, Warner warn) {
 580             return types.isAssignable(found, req, warn);
 581         }
 582 
 583         public Warner checkWarner(DiagnosticPosition pos, Type found, Type req) {
 584             return convertWarner(pos, found, req);
 585         }
 586 
 587         public InferenceContext inferenceContext() {
 588             return infer.emptyContext;
 589         }
 590 
 591         public DeferredAttrContext deferredAttrContext() {
 592             return deferredAttr.emptyDeferredAttrContext;
 593         }
 594 
 595         @Override
 596         public String toString() {
 597             return "CheckContext: basicHandler";
 598         }
 599     };
 600 
 601     /** Check that a given type is assignable to a given proto-type.
 602      *  If it is, return the type, otherwise return errType.
 603      *  @param pos        Position to be used for error reporting.
 604      *  @param found      The type that was found.
 605      *  @param req        The type that was required.
 606      */
 607     public Type checkType(DiagnosticPosition pos, Type found, Type req) {
 608         return checkType(pos, found, req, basicHandler);
 609     }
 610 
 611     Type checkType(final DiagnosticPosition pos, final Type found, final Type req, final CheckContext checkContext) {
 612         final InferenceContext inferenceContext = checkContext.inferenceContext();
 613         if (inferenceContext.free(req) || inferenceContext.free(found)) {
 614             inferenceContext.addFreeTypeListener(List.of(req, found),
 615                     solvedContext -> checkType(pos, solvedContext.asInstType(found), solvedContext.asInstType(req), checkContext));
 616         } else {
 617             if (found.hasTag(CLASS)) {
 618                 if (inferenceContext != infer.emptyContext)
 619                     checkParameterizationByPrimitiveClass(pos, found);
 620             }
 621         }
 622         if (req.hasTag(ERROR))
 623             return req;
 624         if (req.hasTag(NONE))
 625             return found;
 626         if (checkContext.compatible(found, req, checkContext.checkWarner(pos, found, req))) {
 627             return found;
 628         } else {
 629             if (found.isNumeric() && req.isNumeric()) {
 630                 checkContext.report(pos, diags.fragment(Fragments.PossibleLossOfPrecision(found, req)));
 631                 return types.createErrorType(found);
 632             }
 633             checkContext.report(pos, diags.fragment(Fragments.InconvertibleTypes(found, req)));
 634             return types.createErrorType(found);
 635         }
 636     }
 637 
 638     /** Check that a given type can be cast to a given target type.
 639      *  Return the result of the cast.
 640      *  @param pos        Position to be used for error reporting.
 641      *  @param found      The type that is being cast.
 642      *  @param req        The target type of the cast.
 643      */
 644     Type checkCastable(DiagnosticPosition pos, Type found, Type req) {
 645         return checkCastable(pos, found, req, basicHandler);
 646     }
 647     Type checkCastable(DiagnosticPosition pos, Type found, Type req, CheckContext checkContext) {
 648         if (types.isCastable(found, req, castWarner(pos, found, req))) {
 649             return req;
 650         } else {
 651             checkContext.report(pos, diags.fragment(Fragments.InconvertibleTypes(found, req)));
 652             return types.createErrorType(found);
 653         }
 654     }
 655 
 656     /** Check for redundant casts (i.e. where source type is a subtype of target type)
 657      * The problem should only be reported for non-292 cast
 658      */
 659     public void checkRedundantCast(Env<AttrContext> env, final JCTypeCast tree) {
 660         if (!tree.type.isErroneous()
 661                 && types.isSameType(tree.expr.type, tree.clazz.type)
 662                 && !(ignoreAnnotatedCasts && TreeInfo.containsTypeAnnotation(tree.clazz))
 663                 && !is292targetTypeCast(tree)) {
 664             deferredLintHandler.report(() -> {
 665                 if (lint.isEnabled(LintCategory.CAST))
 666                     log.warning(LintCategory.CAST,
 667                             tree.pos(), Warnings.RedundantCast(tree.clazz.type));
 668             });
 669         }
 670     }
 671     //where
 672         private boolean is292targetTypeCast(JCTypeCast tree) {
 673             boolean is292targetTypeCast = false;
 674             JCExpression expr = TreeInfo.skipParens(tree.expr);
 675             if (expr.hasTag(APPLY)) {
 676                 JCMethodInvocation apply = (JCMethodInvocation)expr;
 677                 Symbol sym = TreeInfo.symbol(apply.meth);
 678                 is292targetTypeCast = sym != null &&
 679                     sym.kind == MTH &&
 680                     (sym.flags() & HYPOTHETICAL) != 0;
 681             }
 682             return is292targetTypeCast;
 683         }
 684 
 685         private static final boolean ignoreAnnotatedCasts = true;
 686 
 687     /** Check that a type is within some bounds.
 688      *
 689      *  Used in TypeApply to verify that, e.g., X in {@code V<X>} is a valid
 690      *  type argument.
 691      *  @param a             The type that should be bounded by bs.
 692      *  @param bound         The bound.
 693      */
 694     private boolean checkExtends(Type a, Type bound) {
 695          if (a.isUnbound()) {
 696              return true;
 697          } else if (!a.hasTag(WILDCARD)) {
 698              a = types.cvarUpperBound(a);
 699              return types.isSubtype(a, bound);
 700          } else if (a.isExtendsBound()) {
 701              return types.isCastable(bound, types.wildUpperBound(a), types.noWarnings);
 702          } else if (a.isSuperBound()) {
 703              return !types.notSoftSubtype(types.wildLowerBound(a), bound);
 704          }
 705          return true;
 706      }
 707 
 708     /** Check that type is different from 'void'.
 709      *  @param pos           Position to be used for error reporting.
 710      *  @param t             The type to be checked.
 711      */
 712     Type checkNonVoid(DiagnosticPosition pos, Type t) {
 713         if (t.hasTag(VOID)) {
 714             log.error(pos, Errors.VoidNotAllowedHere);
 715             return types.createErrorType(t);
 716         } else {
 717             return t;
 718         }
 719     }
 720 
 721     Type checkClassOrArrayType(DiagnosticPosition pos, Type t) {
 722         if (!t.hasTag(CLASS) && !t.hasTag(ARRAY) && !t.hasTag(ERROR)) {
 723             return typeTagError(pos,
 724                                 diags.fragment(Fragments.TypeReqClassArray),
 725                                 asTypeParam(t));
 726         } else {
 727             return t;
 728         }
 729     }
 730 
 731     /** Check that type is a class or interface type.
 732      *  @param pos           Position to be used for error reporting.
 733      *  @param t             The type to be checked.
 734      */
 735     Type checkClassType(DiagnosticPosition pos, Type t) {
 736         if (!t.hasTag(CLASS) && !t.hasTag(ERROR)) {
 737             return typeTagError(pos,
 738                                 diags.fragment(Fragments.TypeReqClass),
 739                                 asTypeParam(t));
 740         } else {
 741             return t;
 742         }
 743     }
 744     //where
 745         private Object asTypeParam(Type t) {
 746             return (t.hasTag(TYPEVAR))
 747                                     ? diags.fragment(Fragments.TypeParameter(t))
 748                                     : t;
 749         }
 750 
 751     void checkConstraintsOfValueClass(DiagnosticPosition pos, ClassSymbol c) {
 752         for (Type st : types.closure(c.type)) {
 753             if (st == null || st.tsym == null || st.tsym.kind == ERR)
 754                 continue;
 755             if  (st.tsym == syms.objectType.tsym || st.tsym == syms.recordType.tsym || st.isInterface())
 756                 continue;
 757             if (!st.tsym.isAbstract()) {
 758                 if (c != st.tsym) {
 759                     log.error(pos, Errors.ConcreteSupertypeForValueClass(c, st));
 760                 }
 761                 continue;
 762             }
 763             // dealing with an abstract value or value super class below.
 764             Fragment fragment = c.isAbstract() && c.isValueClass() && c == st.tsym ? Fragments.AbstractValueClass(c) : Fragments.SuperclassOfValueClass(c, st);
 765             if ((st.tsym.flags() & HASINITBLOCK) != 0) {
 766                 log.error(pos, Errors.SuperClassDeclaresInitBlock(fragment));
 767             }
 768             // No instance fields and no arged constructors both mean inner classes
 769             // cannot be super classes for primitive classes.
 770             Type encl = st.getEnclosingType();
 771             if (encl != null && encl.hasTag(CLASS)) {
 772                 log.error(pos, Errors.SuperClassCannotBeInner(fragment));
 773             }
 774             for (Symbol s : st.tsym.members().getSymbols(NON_RECURSIVE)) {
 775                 switch (s.kind) {
 776                 case VAR:
 777                     if ((s.flags() & STATIC) == 0) {
 778                         log.error(pos, Errors.SuperFieldNotAllowed(s, fragment));
 779                     }
 780                     break;
 781                 case MTH:
 782                     if ((s.flags() & (SYNCHRONIZED | STATIC)) == SYNCHRONIZED) {
 783                         log.error(pos, Errors.SuperMethodCannotBeSynchronized(s, c, st));
 784                     } else if (s.isConstructor()) {
 785                         MethodSymbol m = (MethodSymbol)s;
 786                         if (m.getParameters().size() > 0) {
 787                             log.error(pos, Errors.SuperConstructorCannotTakeArguments(m, fragment));
 788                         } else if (m.getTypeParameters().size() > 0) {
 789                             log.error(pos, Errors.SuperConstructorCannotBeGeneric(m, fragment));
 790                         } else if (m.type.getThrownTypes().size() > 0) {
 791                             log.error(pos, Errors.SuperConstructorCannotThrow(m, fragment));
 792                         } else if (protection(m.flags()) > protection(m.owner.flags())) {
 793                             log.error(pos, Errors.SuperConstructorAccessRestricted(m, fragment));
 794                         } else if ((m.flags() & EMPTYNOARGCONSTR) == 0) {
 795                                 log.error(pos, Errors.SuperNoArgConstructorMustBeEmpty(m, fragment));
 796                         }
 797                     }
 798                     break;
 799                 }
 800             }
 801         }
 802     }
 803 
 804     /** Check that type is a valid qualifier for a constructor reference expression
 805      */
 806     Type checkConstructorRefType(JCExpression expr, Type t) {
 807         t = checkClassOrArrayType(expr, t);
 808         if (t.hasTag(CLASS)) {
 809             if ((t.tsym.flags() & (ABSTRACT | INTERFACE)) != 0) {
 810                 log.error(expr, Errors.AbstractCantBeInstantiated(t.tsym));
 811                 t = types.createErrorType(t);
 812             } else if ((t.tsym.flags() & ENUM) != 0) {
 813                 log.error(expr, Errors.EnumCantBeInstantiated);
 814                 t = types.createErrorType(t);
 815             } else {
 816                 // Projection types may not be mentioned in constructor references
 817                 if (expr.hasTag(SELECT)) {
 818                     JCFieldAccess fieldAccess = (JCFieldAccess) expr;
 819                     if (fieldAccess.selected.type.isPrimitiveClass() &&
 820                             (fieldAccess.name == names.ref || fieldAccess.name == names.val)) {
 821                         log.error(expr, Errors.ProjectionCantBeInstantiated);
 822                         t = types.createErrorType(t);
 823                     }
 824                 }
 825                 t = checkClassType(expr, t, true);
 826             }
 827         } else if (t.hasTag(ARRAY)) {
 828             if (!types.isReifiable(((ArrayType)t).elemtype)) {
 829                 log.error(expr, Errors.GenericArrayCreation);
 830                 t = types.createErrorType(t);
 831             }
 832         }
 833         return t;
 834     }
 835 
 836     /** Check that type is a class or interface type.
 837      *  @param pos           Position to be used for error reporting.
 838      *  @param t             The type to be checked.
 839      *  @param noBounds    True if type bounds are illegal here.
 840      */
 841     Type checkClassType(DiagnosticPosition pos, Type t, boolean noBounds) {
 842         t = checkClassType(pos, t);
 843         if (noBounds && t.isParameterized()) {
 844             List<Type> args = t.getTypeArguments();
 845             while (args.nonEmpty()) {
 846                 if (args.head.hasTag(WILDCARD))
 847                     return typeTagError(pos,
 848                                         diags.fragment(Fragments.TypeReqExact),
 849                                         args.head);
 850                 args = args.tail;
 851             }
 852         }
 853         return t;
 854     }
 855 
 856     /** Check that type is a reference type, i.e. a class, interface or array type
 857      *  or a type variable.
 858      *  @param pos           Position to be used for error reporting.
 859      *  @param t             The type to be checked.
 860      *  @param primitiveClassOK       If false, a primitive class does not qualify
 861      */
 862     Type checkRefType(DiagnosticPosition pos, Type t, boolean primitiveClassOK) {
 863         if (t.isReference() && (primitiveClassOK || !t.isPrimitiveClass()))
 864             return t;
 865         else
 866             return typeTagError(pos,
 867                                 diags.fragment(Fragments.TypeReqRef),
 868                                 t);
 869     }
 870 
 871     /** Check that type is an identity type, i.e. not a primitive/value type
 872      *  nor its reference projection. When not discernible statically,
 873      *  give it the benefit of doubt and defer to runtime.
 874      *
 875      *  @param pos           Position to be used for error reporting.
 876      *  @param t             The type to be checked.
 877      */
 878     Type checkIdentityType(DiagnosticPosition pos, Type t) {
 879 
 880         if (t.isPrimitive() || t.isValueClass() || t.isValueInterface() || t.isReferenceProjection())
 881             return typeTagError(pos,
 882                     diags.fragment(Fragments.TypeReqIdentity),
 883                     t);
 884 
 885         return t;
 886     }
 887 
 888     /** Check that type is a reference type, i.e. a class, interface or array type
 889      *  or a type variable.
 890      *  @param pos           Position to be used for error reporting.
 891      *  @param t             The type to be checked.
 892      */
 893     Type checkRefType(DiagnosticPosition pos, Type t) {
 894         return checkRefType(pos, t, true);
 895     }
 896 
 897     /** Check that each type is a reference type, i.e. a class, interface or array type
 898      *  or a type variable.
 899      *  @param trees         Original trees, used for error reporting.
 900      *  @param types         The types to be checked.
 901      */
 902     List<Type> checkRefTypes(List<JCExpression> trees, List<Type> types) {
 903         List<JCExpression> tl = trees;
 904         for (List<Type> l = types; l.nonEmpty(); l = l.tail) {
 905             l.head = checkRefType(tl.head.pos(), l.head, false);
 906             tl = tl.tail;
 907         }
 908         return types;
 909     }
 910 
 911     /** Check that type is a null or reference type.
 912      *  @param pos           Position to be used for error reporting.
 913      *  @param t             The type to be checked.
 914      */
 915     Type checkNullOrRefType(DiagnosticPosition pos, Type t) {
 916         if (t.isReference() || t.hasTag(BOT))
 917             return t;
 918         else
 919             return typeTagError(pos,
 920                                 diags.fragment(Fragments.TypeReqRef),
 921                                 t);
 922     }
 923 
 924     /** Check that flag set does not contain elements of two conflicting sets. s
 925      *  Return true if it doesn't.
 926      *  @param pos           Position to be used for error reporting.
 927      *  @param flags         The set of flags to be checked.
 928      *  @param set1          Conflicting flags set #1.
 929      *  @param set2          Conflicting flags set #2.
 930      */
 931     boolean checkDisjoint(DiagnosticPosition pos, long flags, long set1, long set2) {
 932         if ((flags & set1) != 0 && (flags & set2) != 0) {
 933             log.error(pos,
 934                       Errors.IllegalCombinationOfModifiers(asFlagSet(TreeInfo.firstFlag(flags & set1)),
 935                                                            asFlagSet(TreeInfo.firstFlag(flags & set2))));
 936             return false;
 937         } else
 938             return true;
 939     }
 940 
 941     void checkParameterizationByPrimitiveClass(DiagnosticPosition pos, Type t) {
 942         parameterizationByPrimitiveClassChecker.visit(t, pos);
 943     }
 944 
 945     /** parameterizationByPrimitiveClassChecker: A type visitor that descends down the given type looking for instances of primitive classes
 946      *  being used as type arguments and issues error against those usages.
 947      */
 948     private final Types.SimpleVisitor<Void, DiagnosticPosition> parameterizationByPrimitiveClassChecker =
 949             new Types.SimpleVisitor<Void, DiagnosticPosition>() {
 950 
 951         @Override
 952         public Void visitType(Type t, DiagnosticPosition pos) {
 953             return null;
 954         }
 955 
 956         @Override
 957         public Void visitClassType(ClassType t, DiagnosticPosition pos) {
 958             for (Type targ : t.allparams()) {
 959                 if (targ.isPrimitiveClass()) {
 960                     log.error(pos, Errors.GenericParameterizationWithPrimitiveClass(t));
 961                 }
 962                 visit(targ, pos);
 963             }
 964             return null;
 965         }
 966 
 967         @Override
 968         public Void visitTypeVar(TypeVar t, DiagnosticPosition pos) {
 969              return null;
 970         }
 971 
 972         @Override
 973         public Void visitCapturedType(CapturedType t, DiagnosticPosition pos) {
 974             return null;
 975         }
 976 
 977         @Override
 978         public Void visitArrayType(ArrayType t, DiagnosticPosition pos) {
 979             return visit(t.elemtype, pos);
 980         }
 981 
 982         @Override
 983         public Void visitWildcardType(WildcardType t, DiagnosticPosition pos) {
 984             return visit(t.type, pos);
 985         }
 986     };
 987 
 988 
 989 
 990     /** Check that usage of diamond operator is correct (i.e. diamond should not
 991      * be used with non-generic classes or in anonymous class creation expressions)
 992      */
 993     Type checkDiamond(JCNewClass tree, Type t) {
 994         if (!TreeInfo.isDiamond(tree) ||
 995                 t.isErroneous()) {
 996             return checkClassType(tree.clazz.pos(), t, true);
 997         } else {
 998             if (tree.def != null && !Feature.DIAMOND_WITH_ANONYMOUS_CLASS_CREATION.allowedInSource(source)) {
 999                 log.error(DiagnosticFlag.SOURCE_LEVEL, tree.clazz.pos(),
1000                         Errors.CantApplyDiamond1(t, Feature.DIAMOND_WITH_ANONYMOUS_CLASS_CREATION.fragment(source.name)));
1001             }
1002             if (t.tsym.type.getTypeArguments().isEmpty()) {
1003                 log.error(tree.clazz.pos(),
1004                           Errors.CantApplyDiamond1(t,
1005                                                    Fragments.DiamondNonGeneric(t)));
1006                 return types.createErrorType(t);
1007             } else if (tree.typeargs != null &&
1008                     tree.typeargs.nonEmpty()) {
1009                 log.error(tree.clazz.pos(),
1010                           Errors.CantApplyDiamond1(t,
1011                                                    Fragments.DiamondAndExplicitParams(t)));
1012                 return types.createErrorType(t);
1013             } else {
1014                 return t;
1015             }
1016         }
1017     }
1018 
1019     /** Check that the type inferred using the diamond operator does not contain
1020      *  non-denotable types such as captured types or intersection types.
1021      *  @param t the type inferred using the diamond operator
1022      *  @return  the (possibly empty) list of non-denotable types.
1023      */
1024     List<Type> checkDiamondDenotable(ClassType t) {
1025         ListBuffer<Type> buf = new ListBuffer<>();
1026         for (Type arg : t.allparams()) {
1027             if (!checkDenotable(arg)) {
1028                 buf.append(arg);
1029             }
1030         }
1031         return buf.toList();
1032     }
1033 
1034     public boolean checkDenotable(Type t) {
1035         return denotableChecker.visit(t, null);
1036     }
1037         // where
1038 
1039         /** diamondTypeChecker: A type visitor that descends down the given type looking for non-denotable
1040          *  types. The visit methods return false as soon as a non-denotable type is encountered and true
1041          *  otherwise.
1042          */
1043         private static final Types.SimpleVisitor<Boolean, Void> denotableChecker = new Types.SimpleVisitor<Boolean, Void>() {
1044             @Override
1045             public Boolean visitType(Type t, Void s) {
1046                 return true;
1047             }
1048             @Override
1049             public Boolean visitClassType(ClassType t, Void s) {
1050                 if (t.isUnion() || t.isIntersection()) {
1051                     return false;
1052                 }
1053                 for (Type targ : t.allparams()) {
1054                     if (!visit(targ, s)) {
1055                         return false;
1056                     }
1057                 }
1058                 return true;
1059             }
1060 
1061             @Override
1062             public Boolean visitTypeVar(TypeVar t, Void s) {
1063                 /* Any type variable mentioned in the inferred type must have been declared as a type parameter
1064                   (i.e cannot have been produced by inference (18.4))
1065                 */
1066                 return (t.tsym.flags() & SYNTHETIC) == 0;
1067             }
1068 
1069             @Override
1070             public Boolean visitCapturedType(CapturedType t, Void s) {
1071                 /* Any type variable mentioned in the inferred type must have been declared as a type parameter
1072                   (i.e cannot have been produced by capture conversion (5.1.10))
1073                 */
1074                 return false;
1075             }
1076 
1077             @Override
1078             public Boolean visitArrayType(ArrayType t, Void s) {
1079                 return visit(t.elemtype, s);
1080             }
1081 
1082             @Override
1083             public Boolean visitWildcardType(WildcardType t, Void s) {
1084                 return visit(t.type, s);
1085             }
1086         };
1087 
1088     void checkVarargsMethodDecl(Env<AttrContext> env, JCMethodDecl tree) {
1089         MethodSymbol m = tree.sym;
1090         boolean hasTrustMeAnno = m.attribute(syms.trustMeType.tsym) != null;
1091         Type varargElemType = null;
1092         if (m.isVarArgs()) {
1093             varargElemType = types.elemtype(tree.params.last().type);
1094         }
1095         if (hasTrustMeAnno && !isTrustMeAllowedOnMethod(m)) {
1096             if (varargElemType != null) {
1097                 JCDiagnostic msg = Feature.PRIVATE_SAFE_VARARGS.allowedInSource(source) ?
1098                         diags.fragment(Fragments.VarargsTrustmeOnVirtualVarargs(m)) :
1099                         diags.fragment(Fragments.VarargsTrustmeOnVirtualVarargsFinalOnly(m));
1100                 log.error(tree,
1101                           Errors.VarargsInvalidTrustmeAnno(syms.trustMeType.tsym,
1102                                                            msg));
1103             } else {
1104                 log.error(tree,
1105                           Errors.VarargsInvalidTrustmeAnno(syms.trustMeType.tsym,
1106                                                            Fragments.VarargsTrustmeOnNonVarargsMeth(m)));
1107             }
1108         } else if (hasTrustMeAnno && varargElemType != null &&
1109                             types.isReifiable(varargElemType)) {
1110             warnUnsafeVararg(tree, Warnings.VarargsRedundantTrustmeAnno(
1111                                 syms.trustMeType.tsym,
1112                                 diags.fragment(Fragments.VarargsTrustmeOnReifiableVarargs(varargElemType))));
1113         }
1114         else if (!hasTrustMeAnno && varargElemType != null &&
1115                 !types.isReifiable(varargElemType)) {
1116             warnUnchecked(tree.params.head.pos(), Warnings.UncheckedVarargsNonReifiableType(varargElemType));
1117         }
1118     }
1119     //where
1120         private boolean isTrustMeAllowedOnMethod(Symbol s) {
1121             return (s.flags() & VARARGS) != 0 &&
1122                 (s.isConstructor() ||
1123                     (s.flags() & (STATIC | FINAL |
1124                                   (Feature.PRIVATE_SAFE_VARARGS.allowedInSource(source) ? PRIVATE : 0) )) != 0);
1125         }
1126 
1127     Type checkLocalVarType(DiagnosticPosition pos, Type t, Name name) {
1128         //check that resulting type is not the null type
1129         if (t.hasTag(BOT)) {
1130             log.error(pos, Errors.CantInferLocalVarType(name, Fragments.LocalCantInferNull));
1131             return types.createErrorType(t);
1132         } else if (t.hasTag(VOID)) {
1133             log.error(pos, Errors.CantInferLocalVarType(name, Fragments.LocalCantInferVoid));
1134             return types.createErrorType(t);
1135         }
1136 
1137         //upward project the initializer type
1138         Type varType = types.upward(t, types.captures(t));
1139         if (varType.hasTag(CLASS)) {
1140             checkParameterizationByPrimitiveClass(pos, varType);
1141         }
1142         return varType;
1143     }
1144 
1145     public void checkForSuspectClassLiteralComparison(
1146             final JCBinary tree,
1147             final Type leftType,
1148             final Type rightType) {
1149 
1150         if (lint.isEnabled(LintCategory.MIGRATION)) {
1151             if (isInvocationOfGetClass(tree.lhs) && isClassOfSomeInterface(rightType) ||
1152                     isInvocationOfGetClass(tree.rhs) && isClassOfSomeInterface(leftType)) {
1153                 log.warning(LintCategory.MIGRATION, tree.pos(), Warnings.GetClassComparedWithInterface);
1154             }
1155         }
1156     }
1157     //where
1158     private boolean isClassOfSomeInterface(Type someClass) {
1159         if (someClass.tsym.flatName() == names.java_lang_Class) {
1160             List<Type> arguments = someClass.getTypeArguments();
1161             if (arguments.length() == 1) {
1162                 return arguments.head.isInterface();
1163             }
1164         }
1165         return false;
1166     }
1167     //where
1168     private boolean isInvocationOfGetClass(JCExpression tree) {
1169         tree = TreeInfo.skipParens(tree);
1170         if (tree.hasTag(APPLY)) {
1171             JCMethodInvocation apply = (JCMethodInvocation)tree;
1172             MethodSymbol msym = (MethodSymbol)TreeInfo.symbol(apply.meth);
1173             return msym.name == names.getClass && msym.implementedIn(syms.objectType.tsym, types) != null;
1174         }
1175         return false;
1176     }
1177 
1178     Type checkMethod(final Type mtype,
1179             final Symbol sym,
1180             final Env<AttrContext> env,
1181             final List<JCExpression> argtrees,
1182             final List<Type> argtypes,
1183             final boolean useVarargs,
1184             InferenceContext inferenceContext) {
1185         // System.out.println("call   : " + env.tree);
1186         // System.out.println("method : " + owntype);
1187         // System.out.println("actuals: " + argtypes);
1188         if (inferenceContext.free(mtype)) {
1189             inferenceContext.addFreeTypeListener(List.of(mtype),
1190                     solvedContext -> checkMethod(solvedContext.asInstType(mtype), sym, env, argtrees, argtypes, useVarargs, solvedContext));
1191             return mtype;
1192         }
1193         Type owntype = mtype;
1194         List<Type> formals = owntype.getParameterTypes();
1195         List<Type> nonInferred = sym.type.getParameterTypes();
1196         if (nonInferred.length() != formals.length()) nonInferred = formals;
1197         Type last = useVarargs ? formals.last() : null;
1198         if (sym.name == names.init && sym.owner == syms.enumSym) {
1199             formals = formals.tail.tail;
1200             nonInferred = nonInferred.tail.tail;
1201         }
1202         if ((sym.flags() & ANONCONSTR_BASED) != 0) {
1203             formals = formals.tail;
1204             nonInferred = nonInferred.tail;
1205         }
1206         List<JCExpression> args = argtrees;
1207         if (args != null) {
1208             //this is null when type-checking a method reference
1209             while (formals.head != last) {
1210                 JCTree arg = args.head;
1211                 Warner warn = convertWarner(arg.pos(), arg.type, nonInferred.head);
1212                 assertConvertible(arg, arg.type, formals.head, warn);
1213                 args = args.tail;
1214                 formals = formals.tail;
1215                 nonInferred = nonInferred.tail;
1216             }
1217             if (useVarargs) {
1218                 Type varArg = types.elemtype(last);
1219                 while (args.tail != null) {
1220                     JCTree arg = args.head;
1221                     Warner warn = convertWarner(arg.pos(), arg.type, varArg);
1222                     assertConvertible(arg, arg.type, varArg, warn);
1223                     args = args.tail;
1224                 }
1225             } else if ((sym.flags() & (VARARGS | SIGNATURE_POLYMORPHIC)) == VARARGS) {
1226                 // non-varargs call to varargs method
1227                 Type varParam = owntype.getParameterTypes().last();
1228                 Type lastArg = argtypes.last();
1229                 if (types.isSubtypeUnchecked(lastArg, types.elemtype(varParam)) &&
1230                     !types.isSameType(types.erasure(varParam), types.erasure(lastArg)))
1231                     log.warning(argtrees.last().pos(),
1232                                 Warnings.InexactNonVarargsCall(types.elemtype(varParam),varParam));
1233             }
1234         }
1235         if (useVarargs) {
1236             Type argtype = owntype.getParameterTypes().last();
1237             if (!types.isReifiable(argtype) &&
1238                 (sym.baseSymbol().attribute(syms.trustMeType.tsym) == null ||
1239                  !isTrustMeAllowedOnMethod(sym))) {
1240                 warnUnchecked(env.tree.pos(), Warnings.UncheckedGenericArrayCreation(argtype));
1241             }
1242             TreeInfo.setVarargsElement(env.tree, types.elemtype(argtype));
1243          }
1244          return owntype;
1245     }
1246     //where
1247     private void assertConvertible(JCTree tree, Type actual, Type formal, Warner warn) {
1248         if (types.isConvertible(actual, formal, warn))
1249             return;
1250 
1251         if (formal.isCompound()
1252             && types.isSubtype(actual, types.supertype(formal))
1253             && types.isSubtypeUnchecked(actual, types.interfaces(formal), warn))
1254             return;
1255     }
1256 
1257     /**
1258      * Check that type 't' is a valid instantiation of a generic class
1259      * (see JLS 4.5)
1260      *
1261      * @param t class type to be checked
1262      * @return true if 't' is well-formed
1263      */
1264     public boolean checkValidGenericType(Type t) {
1265         return firstIncompatibleTypeArg(t) == null;
1266     }
1267     //WHERE
1268         private Type firstIncompatibleTypeArg(Type type) {
1269             List<Type> formals = type.tsym.type.allparams();
1270             List<Type> actuals = type.allparams();
1271             List<Type> args = type.getTypeArguments();
1272             List<Type> forms = type.tsym.type.getTypeArguments();
1273             ListBuffer<Type> bounds_buf = new ListBuffer<>();
1274 
1275             // For matching pairs of actual argument types `a' and
1276             // formal type parameters with declared bound `b' ...
1277             while (args.nonEmpty() && forms.nonEmpty()) {
1278                 // exact type arguments needs to know their
1279                 // bounds (for upper and lower bound
1280                 // calculations).  So we create new bounds where
1281                 // type-parameters are replaced with actuals argument types.
1282                 bounds_buf.append(types.subst(forms.head.getUpperBound(), formals, actuals));
1283                 args = args.tail;
1284                 forms = forms.tail;
1285             }
1286 
1287             args = type.getTypeArguments();
1288             List<Type> tvars_cap = types.substBounds(formals,
1289                                       formals,
1290                                       types.capture(type).allparams());
1291             while (args.nonEmpty() && tvars_cap.nonEmpty()) {
1292                 // Let the actual arguments know their bound
1293                 args.head.withTypeVar((TypeVar)tvars_cap.head);
1294                 args = args.tail;
1295                 tvars_cap = tvars_cap.tail;
1296             }
1297 
1298             args = type.getTypeArguments();
1299             List<Type> bounds = bounds_buf.toList();
1300 
1301             while (args.nonEmpty() && bounds.nonEmpty()) {
1302                 Type actual = args.head;
1303                 if (!isTypeArgErroneous(actual) &&
1304                         !bounds.head.isErroneous() &&
1305                         !checkExtends(actual, bounds.head)) {
1306                     return args.head;
1307                 }
1308                 args = args.tail;
1309                 bounds = bounds.tail;
1310             }
1311 
1312             args = type.getTypeArguments();
1313             bounds = bounds_buf.toList();
1314 
1315             for (Type arg : types.capture(type).getTypeArguments()) {
1316                 if (arg.hasTag(TYPEVAR) &&
1317                         arg.getUpperBound().isErroneous() &&
1318                         !bounds.head.isErroneous() &&
1319                         !isTypeArgErroneous(args.head)) {
1320                     return args.head;
1321                 }
1322                 bounds = bounds.tail;
1323                 args = args.tail;
1324             }
1325 
1326             return null;
1327         }
1328         //where
1329         boolean isTypeArgErroneous(Type t) {
1330             return isTypeArgErroneous.visit(t);
1331         }
1332 
1333         Types.UnaryVisitor<Boolean> isTypeArgErroneous = new Types.UnaryVisitor<Boolean>() {
1334             public Boolean visitType(Type t, Void s) {
1335                 return t.isErroneous();
1336             }
1337             @Override
1338             public Boolean visitTypeVar(TypeVar t, Void s) {
1339                 return visit(t.getUpperBound());
1340             }
1341             @Override
1342             public Boolean visitCapturedType(CapturedType t, Void s) {
1343                 return visit(t.getUpperBound()) ||
1344                         visit(t.getLowerBound());
1345             }
1346             @Override
1347             public Boolean visitWildcardType(WildcardType t, Void s) {
1348                 return visit(t.type);
1349             }
1350         };
1351 
1352     /** Check that given modifiers are legal for given symbol and
1353      *  return modifiers together with any implicit modifiers for that symbol.
1354      *  Warning: we can't use flags() here since this method
1355      *  is called during class enter, when flags() would cause a premature
1356      *  completion.
1357      *  @param pos           Position to be used for error reporting.
1358      *  @param flags         The set of modifiers given in a definition.
1359      *  @param sym           The defined symbol.
1360      */
1361     long checkFlags(DiagnosticPosition pos, long flags, Symbol sym, JCTree tree) {
1362         long mask;
1363         long implicit = 0;
1364 
1365         switch (sym.kind) {
1366         case VAR:
1367             if (TreeInfo.isReceiverParam(tree))
1368                 mask = ReceiverParamFlags;
1369             else if (sym.owner.kind != TYP)
1370                 mask = LocalVarFlags;
1371             else if ((sym.owner.flags_field & INTERFACE) != 0)
1372                 mask = implicit = InterfaceVarFlags;
1373             else {
1374                 mask = VarFlags;
1375                 if (sym.owner.type.isValueClass() && (flags & STATIC) == 0) {
1376                     implicit |= FINAL;
1377                 }
1378             }
1379             break;
1380         case MTH:
1381             if (sym.name == names.init) {
1382                 if ((sym.owner.flags_field & ENUM) != 0) {
1383                     // enum constructors cannot be declared public or
1384                     // protected and must be implicitly or explicitly
1385                     // private
1386                     implicit = PRIVATE;
1387                     mask = PRIVATE;
1388                 } else
1389                     mask = ConstructorFlags;
1390             }  else if ((sym.owner.flags_field & INTERFACE) != 0) {
1391                 if ((sym.owner.flags_field & ANNOTATION) != 0) {
1392                     mask = AnnotationTypeElementMask;
1393                     implicit = PUBLIC | ABSTRACT;
1394                 } else if ((flags & (DEFAULT | STATIC | PRIVATE)) != 0) {
1395                     mask = InterfaceMethodMask;
1396                     implicit = (flags & PRIVATE) != 0 ? 0 : PUBLIC;
1397                     if ((flags & DEFAULT) != 0) {
1398                         implicit |= ABSTRACT;
1399                     }
1400                 } else {
1401                     mask = implicit = InterfaceMethodFlags;
1402                 }
1403             } else if ((sym.owner.flags_field & RECORD) != 0) {
1404                 mask = ((sym.owner.flags_field & VALUE_CLASS) != 0 && (flags & Flags.STATIC) == 0) ?
1405                         RecordMethodFlags & ~SYNCHRONIZED : RecordMethodFlags;
1406             } else {
1407                 // value objects do not have an associated monitor/lock
1408                 mask = ((sym.owner.flags_field & VALUE_CLASS) != 0 && (flags & Flags.STATIC) == 0) ?
1409                         MethodFlags & ~SYNCHRONIZED : MethodFlags;
1410             }
1411             if ((flags & STRICTFP) != 0) {
1412                 warnOnExplicitStrictfp(pos);
1413             }
1414             // Imply STRICTFP if owner has STRICTFP set.
1415             if (((flags|implicit) & Flags.ABSTRACT) == 0 ||
1416                 ((flags) & Flags.DEFAULT) != 0)
1417                 implicit |= sym.owner.flags_field & STRICTFP;
1418             break;
1419         case TYP:
1420             if (sym.owner.kind.matches(KindSelector.VAL_MTH) ||
1421                     (sym.isDirectlyOrIndirectlyLocal() && (flags & ANNOTATION) != 0)) {
1422                 boolean implicitlyStatic = !sym.isAnonymous() &&
1423                         ((flags & RECORD) != 0 || (flags & ENUM) != 0 || (flags & INTERFACE) != 0);
1424                 boolean staticOrImplicitlyStatic = (flags & STATIC) != 0 || implicitlyStatic;
1425                 // local statics are allowed only if records are allowed too
1426                 mask = staticOrImplicitlyStatic && allowRecords && (flags & ANNOTATION) == 0 ? ExtendedStaticLocalClassFlags : ExtendedLocalClassFlags;
1427                 implicit = implicitlyStatic ? STATIC : implicit;
1428             } else if (sym.owner.kind == TYP) {
1429                 // statics in inner classes are allowed only if records are allowed too
1430                 mask = ((flags & STATIC) != 0) && allowRecords && (flags & ANNOTATION) == 0 ? ExtendedMemberStaticClassFlags : ExtendedMemberClassFlags;
1431                 if (sym.owner.owner.kind == PCK ||
1432                     (sym.owner.flags_field & STATIC) != 0) {
1433                     mask |= STATIC;
1434                 } else if (!allowRecords && ((flags & ENUM) != 0 || (flags & RECORD) != 0)) {
1435                     log.error(pos, Errors.StaticDeclarationNotAllowedInInnerClasses);
1436                 }
1437                 // Nested interfaces and enums are always STATIC (Spec ???)
1438                 if ((flags & (INTERFACE | ENUM | RECORD)) != 0 ) implicit = STATIC;
1439             } else {
1440                 mask = ExtendedClassFlags;
1441             }
1442             // Interfaces are always ABSTRACT
1443             if ((flags & INTERFACE) != 0) implicit |= ABSTRACT;
1444 
1445             if ((flags & ENUM) != 0) {
1446                 // enums can't be declared abstract, final, sealed or non-sealed or primitive/value
1447                 mask &= ~(ABSTRACT | FINAL | SEALED | NON_SEALED | PRIMITIVE_CLASS | VALUE_CLASS);
1448                 implicit |= implicitEnumFinalFlag(tree);
1449             }
1450             if ((flags & RECORD) != 0) {
1451                 // records can't be declared abstract
1452                 mask &= ~ABSTRACT;
1453                 implicit |= FINAL;
1454             }
1455             if ((flags & STRICTFP) != 0) {
1456                 warnOnExplicitStrictfp(pos);
1457             }
1458             // Imply STRICTFP if owner has STRICTFP set.
1459             implicit |= sym.owner.flags_field & STRICTFP;
1460 
1461             // primitive classes are implicitly final value classes.
1462             if ((flags & PRIMITIVE_CLASS) != 0)
1463                 implicit |= VALUE_CLASS | FINAL;
1464 
1465             // concrete value classes are implicitly final
1466             if ((flags & (ABSTRACT | INTERFACE | VALUE_CLASS)) == VALUE_CLASS)
1467                 implicit |= FINAL;
1468 
1469             // TYPs can't be declared synchronized
1470             mask &= ~SYNCHRONIZED;
1471             break;
1472         default:
1473             throw new AssertionError();
1474         }
1475         long illegal = flags & ExtendedStandardFlags & ~mask;
1476         if (illegal != 0) {
1477             if ((illegal & INTERFACE) != 0) {
1478                 log.error(pos, ((flags & ANNOTATION) != 0) ? Errors.AnnotationDeclNotAllowedHere : Errors.IntfNotAllowedHere);
1479                 mask |= INTERFACE;
1480             }
1481             else {
1482                 log.error(pos,
1483                         Errors.ModNotAllowedHere(asFlagSet(illegal)));
1484             }
1485         }
1486         else if ((sym.kind == TYP ||
1487                   // ISSUE: Disallowing abstract&private is no longer appropriate
1488                   // in the presence of inner classes. Should it be deleted here?
1489                   checkDisjoint(pos, flags,
1490                                 ABSTRACT,
1491                                 PRIVATE | STATIC | DEFAULT))
1492                  &&
1493                  checkDisjoint(pos, flags,
1494                                 STATIC | PRIVATE,
1495                                 DEFAULT)
1496                  &&
1497                  checkDisjoint(pos, flags,
1498                                ABSTRACT | INTERFACE,
1499                                FINAL | NATIVE | SYNCHRONIZED | PRIMITIVE_CLASS)
1500                  &&
1501                  checkDisjoint(pos, flags,
1502                         IDENTITY_TYPE,
1503                         PRIMITIVE_CLASS | VALUE_CLASS)
1504                  &&
1505                  checkDisjoint(pos, flags,
1506                                PUBLIC,
1507                                PRIVATE | PROTECTED)
1508                  &&
1509                  checkDisjoint(pos, flags,
1510                                PRIVATE,
1511                                PUBLIC | PROTECTED)
1512                  &&
1513                  checkDisjoint(pos, (flags | implicit), // complain against volatile & implcitly final entities too.
1514                                FINAL,
1515                                VOLATILE)
1516                  &&
1517                  (sym.kind == TYP ||
1518                   checkDisjoint(pos, flags,
1519                                 ABSTRACT | NATIVE,
1520                                 STRICTFP))
1521                  && checkDisjoint(pos, flags,
1522                                 FINAL,
1523                            SEALED | NON_SEALED)
1524                  && checkDisjoint(pos, flags,
1525                                 SEALED,
1526                            FINAL | NON_SEALED)
1527                  && checkDisjoint(pos, flags,
1528                                 SEALED,
1529                                 ANNOTATION)) {
1530             // skip
1531         }
1532         return flags & (mask | ~ExtendedStandardFlags) | implicit;
1533     }
1534 
1535     private void warnOnExplicitStrictfp(DiagnosticPosition pos) {
1536         DiagnosticPosition prevLintPos = deferredLintHandler.setPos(pos);
1537         try {
1538             deferredLintHandler.report(() -> {
1539                                            if (lint.isEnabled(LintCategory.STRICTFP)) {
1540                                                log.warning(LintCategory.STRICTFP,
1541                                                            pos, Warnings.Strictfp); }
1542                                        });
1543         } finally {
1544             deferredLintHandler.setPos(prevLintPos);
1545         }
1546     }
1547 
1548 
1549     /** Determine if this enum should be implicitly final.
1550      *
1551      *  If the enum has no specialized enum constants, it is final.
1552      *
1553      *  If the enum does have specialized enum constants, it is
1554      *  <i>not</i> final.
1555      */
1556     private long implicitEnumFinalFlag(JCTree tree) {
1557         if (!tree.hasTag(CLASSDEF)) return 0;
1558         class SpecialTreeVisitor extends JCTree.Visitor {
1559             boolean specialized;
1560             SpecialTreeVisitor() {
1561                 this.specialized = false;
1562             }
1563 
1564             @Override
1565             public void visitTree(JCTree tree) { /* no-op */ }
1566 
1567             @Override
1568             public void visitVarDef(JCVariableDecl tree) {
1569                 if ((tree.mods.flags & ENUM) != 0) {
1570                     if (tree.init instanceof JCNewClass newClass && newClass.def != null) {
1571                         specialized = true;
1572                     }
1573                 }
1574             }
1575         }
1576 
1577         SpecialTreeVisitor sts = new SpecialTreeVisitor();
1578         JCClassDecl cdef = (JCClassDecl) tree;
1579         for (JCTree defs: cdef.defs) {
1580             defs.accept(sts);
1581             if (sts.specialized) return allowSealed ? SEALED : 0;
1582         }
1583         return FINAL;
1584     }
1585 
1586 /* *************************************************************************
1587  * Type Validation
1588  **************************************************************************/
1589 
1590     /** Validate a type expression. That is,
1591      *  check that all type arguments of a parametric type are within
1592      *  their bounds. This must be done in a second phase after type attribution
1593      *  since a class might have a subclass as type parameter bound. E.g:
1594      *
1595      *  <pre>{@code
1596      *  class B<A extends C> { ... }
1597      *  class C extends B<C> { ... }
1598      *  }</pre>
1599      *
1600      *  and we can't make sure that the bound is already attributed because
1601      *  of possible cycles.
1602      *
1603      * Visitor method: Validate a type expression, if it is not null, catching
1604      *  and reporting any completion failures.
1605      */
1606     void validate(JCTree tree, Env<AttrContext> env) {
1607         validate(tree, env, true);
1608     }
1609     void validate(JCTree tree, Env<AttrContext> env, boolean checkRaw) {
1610         new Validator(env).validateTree(tree, checkRaw, true);
1611     }
1612 
1613     /** Visitor method: Validate a list of type expressions.
1614      */
1615     void validate(List<? extends JCTree> trees, Env<AttrContext> env) {
1616         for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
1617             validate(l.head, env);
1618     }
1619 
1620     /** A visitor class for type validation.
1621      */
1622     class Validator extends JCTree.Visitor {
1623 
1624         boolean checkRaw;
1625         boolean isOuter;
1626         Env<AttrContext> env;
1627 
1628         Validator(Env<AttrContext> env) {
1629             this.env = env;
1630         }
1631 
1632         @Override
1633         public void visitTypeArray(JCArrayTypeTree tree) {
1634             validateTree(tree.elemtype, checkRaw, isOuter);
1635         }
1636 
1637         @Override
1638         public void visitTypeApply(JCTypeApply tree) {
1639             if (tree.type.hasTag(CLASS)) {
1640                 List<JCExpression> args = tree.arguments;
1641                 List<Type> forms = tree.type.tsym.type.getTypeArguments();
1642 
1643                 Type incompatibleArg = firstIncompatibleTypeArg(tree.type);
1644                 if (incompatibleArg != null) {
1645                     for (JCTree arg : tree.arguments) {
1646                         if (arg.type == incompatibleArg) {
1647                             log.error(arg, Errors.NotWithinBounds(incompatibleArg, forms.head));
1648                         }
1649                         forms = forms.tail;
1650                      }
1651                  }
1652 
1653                 forms = tree.type.tsym.type.getTypeArguments();
1654 
1655                 boolean is_java_lang_Class = tree.type.tsym.flatName() == names.java_lang_Class;
1656 
1657                 // For matching pairs of actual argument types `a' and
1658                 // formal type parameters with declared bound `b' ...
1659                 while (args.nonEmpty() && forms.nonEmpty()) {
1660                     validateTree(args.head,
1661                             !(isOuter && is_java_lang_Class),
1662                             false);
1663                     args = args.tail;
1664                     forms = forms.tail;
1665                 }
1666 
1667                 // Check that this type is either fully parameterized, or
1668                 // not parameterized at all.
1669                 if (tree.type.getEnclosingType().isRaw())
1670                     log.error(tree.pos(), Errors.ImproperlyFormedTypeInnerRawParam);
1671                 if (tree.clazz.hasTag(SELECT))
1672                     visitSelectInternal((JCFieldAccess)tree.clazz);
1673             }
1674         }
1675 
1676         @Override
1677         public void visitTypeParameter(JCTypeParameter tree) {
1678             validateTrees(tree.bounds, true, isOuter);
1679             checkClassBounds(tree.pos(), tree.type);
1680         }
1681 
1682         @Override
1683         public void visitWildcard(JCWildcard tree) {
1684             if (tree.inner != null)
1685                 validateTree(tree.inner, true, isOuter);
1686         }
1687 
1688         @Override
1689         public void visitSelect(JCFieldAccess tree) {
1690             if (tree.type.hasTag(CLASS)) {
1691                 visitSelectInternal(tree);
1692 
1693                 // Check that this type is either fully parameterized, or
1694                 // not parameterized at all.
1695                 if (tree.selected.type.isParameterized() && tree.type.tsym.type.getTypeArguments().nonEmpty())
1696                     log.error(tree.pos(), Errors.ImproperlyFormedTypeParamMissing);
1697             }
1698         }
1699 
1700         public void visitSelectInternal(JCFieldAccess tree) {
1701             if (tree.type.tsym.isStatic() &&
1702                 tree.selected.type.isParameterized() &&
1703                     (tree.name != names.ref || !tree.type.isReferenceProjection())) {
1704                 // The enclosing type is not a class, so we are
1705                 // looking at a static member type.  However, the
1706                 // qualifying expression is parameterized.
1707                 // Tolerate the pseudo-select V.ref: V<T>.ref will be static if V<T> is and
1708                 // should not be confused as selecting a static member of a parameterized type.
1709                 log.error(tree.pos(), Errors.CantSelectStaticClassFromParamType);
1710             } else {
1711                 // otherwise validate the rest of the expression
1712                 tree.selected.accept(this);
1713             }
1714         }
1715 
1716         @Override
1717         public void visitAnnotatedType(JCAnnotatedType tree) {
1718             tree.underlyingType.accept(this);
1719         }
1720 
1721         @Override
1722         public void visitTypeIdent(JCPrimitiveTypeTree that) {
1723             if (that.type.hasTag(TypeTag.VOID)) {
1724                 log.error(that.pos(), Errors.VoidNotAllowedHere);
1725             }
1726             super.visitTypeIdent(that);
1727         }
1728 
1729         /** Default visitor method: do nothing.
1730          */
1731         @Override
1732         public void visitTree(JCTree tree) {
1733         }
1734 
1735         public void validateTree(JCTree tree, boolean checkRaw, boolean isOuter) {
1736             if (tree != null) {
1737                 boolean prevCheckRaw = this.checkRaw;
1738                 this.checkRaw = checkRaw;
1739                 this.isOuter = isOuter;
1740 
1741                 try {
1742                     tree.accept(this);
1743                     if (checkRaw)
1744                         checkRaw(tree, env);
1745                 } catch (CompletionFailure ex) {
1746                     completionError(tree.pos(), ex);
1747                 } finally {
1748                     this.checkRaw = prevCheckRaw;
1749                 }
1750             }
1751         }
1752 
1753         public void validateTrees(List<? extends JCTree> trees, boolean checkRaw, boolean isOuter) {
1754             for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
1755                 validateTree(l.head, checkRaw, isOuter);
1756         }
1757     }
1758 
1759     void checkRaw(JCTree tree, Env<AttrContext> env) {
1760         if (lint.isEnabled(LintCategory.RAW) &&
1761             tree.type.hasTag(CLASS) &&
1762             !TreeInfo.isDiamond(tree) &&
1763             !withinAnonConstr(env) &&
1764             tree.type.isRaw()) {
1765             log.warning(LintCategory.RAW,
1766                     tree.pos(), Warnings.RawClassUse(tree.type, tree.type.tsym.type));
1767         }
1768     }
1769     //where
1770         private boolean withinAnonConstr(Env<AttrContext> env) {
1771             return env.enclClass.name.isEmpty() &&
1772                     env.enclMethod != null && env.enclMethod.name == names.init;
1773         }
1774 
1775 /* *************************************************************************
1776  * Exception checking
1777  **************************************************************************/
1778 
1779     /* The following methods treat classes as sets that contain
1780      * the class itself and all their subclasses
1781      */
1782 
1783     /** Is given type a subtype of some of the types in given list?
1784      */
1785     boolean subset(Type t, List<Type> ts) {
1786         for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
1787             if (types.isSubtype(t, l.head)) return true;
1788         return false;
1789     }
1790 
1791     /** Is given type a subtype or supertype of
1792      *  some of the types in given list?
1793      */
1794     boolean intersects(Type t, List<Type> ts) {
1795         for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
1796             if (types.isSubtype(t, l.head) || types.isSubtype(l.head, t)) return true;
1797         return false;
1798     }
1799 
1800     /** Add type set to given type list, unless it is a subclass of some class
1801      *  in the list.
1802      */
1803     List<Type> incl(Type t, List<Type> ts) {
1804         return subset(t, ts) ? ts : excl(t, ts).prepend(t);
1805     }
1806 
1807     /** Remove type set from type set list.
1808      */
1809     List<Type> excl(Type t, List<Type> ts) {
1810         if (ts.isEmpty()) {
1811             return ts;
1812         } else {
1813             List<Type> ts1 = excl(t, ts.tail);
1814             if (types.isSubtype(ts.head, t)) return ts1;
1815             else if (ts1 == ts.tail) return ts;
1816             else return ts1.prepend(ts.head);
1817         }
1818     }
1819 
1820     /** Form the union of two type set lists.
1821      */
1822     List<Type> union(List<Type> ts1, List<Type> ts2) {
1823         List<Type> ts = ts1;
1824         for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
1825             ts = incl(l.head, ts);
1826         return ts;
1827     }
1828 
1829     /** Form the difference of two type lists.
1830      */
1831     List<Type> diff(List<Type> ts1, List<Type> ts2) {
1832         List<Type> ts = ts1;
1833         for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
1834             ts = excl(l.head, ts);
1835         return ts;
1836     }
1837 
1838     /** Form the intersection of two type lists.
1839      */
1840     public List<Type> intersect(List<Type> ts1, List<Type> ts2) {
1841         List<Type> ts = List.nil();
1842         for (List<Type> l = ts1; l.nonEmpty(); l = l.tail)
1843             if (subset(l.head, ts2)) ts = incl(l.head, ts);
1844         for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
1845             if (subset(l.head, ts1)) ts = incl(l.head, ts);
1846         return ts;
1847     }
1848 
1849     /** Is exc an exception symbol that need not be declared?
1850      */
1851     boolean isUnchecked(ClassSymbol exc) {
1852         return
1853             exc.kind == ERR ||
1854             exc.isSubClass(syms.errorType.tsym, types) ||
1855             exc.isSubClass(syms.runtimeExceptionType.tsym, types);
1856     }
1857 
1858     /** Is exc an exception type that need not be declared?
1859      */
1860     boolean isUnchecked(Type exc) {
1861         return
1862             (exc.hasTag(TYPEVAR)) ? isUnchecked(types.supertype(exc)) :
1863             (exc.hasTag(CLASS)) ? isUnchecked((ClassSymbol)exc.tsym) :
1864             exc.hasTag(BOT);
1865     }
1866 
1867     boolean isChecked(Type exc) {
1868         return !isUnchecked(exc);
1869     }
1870 
1871     /** Same, but handling completion failures.
1872      */
1873     boolean isUnchecked(DiagnosticPosition pos, Type exc) {
1874         try {
1875             return isUnchecked(exc);
1876         } catch (CompletionFailure ex) {
1877             completionError(pos, ex);
1878             return true;
1879         }
1880     }
1881 
1882     /** Is exc handled by given exception list?
1883      */
1884     boolean isHandled(Type exc, List<Type> handled) {
1885         return isUnchecked(exc) || subset(exc, handled);
1886     }
1887 
1888     /** Return all exceptions in thrown list that are not in handled list.
1889      *  @param thrown     The list of thrown exceptions.
1890      *  @param handled    The list of handled exceptions.
1891      */
1892     List<Type> unhandled(List<Type> thrown, List<Type> handled) {
1893         List<Type> unhandled = List.nil();
1894         for (List<Type> l = thrown; l.nonEmpty(); l = l.tail)
1895             if (!isHandled(l.head, handled)) unhandled = unhandled.prepend(l.head);
1896         return unhandled;
1897     }
1898 
1899 /* *************************************************************************
1900  * Overriding/Implementation checking
1901  **************************************************************************/
1902 
1903     /** The level of access protection given by a flag set,
1904      *  where PRIVATE is highest and PUBLIC is lowest.
1905      */
1906     static int protection(long flags) {
1907         switch ((short)(flags & AccessFlags)) {
1908         case PRIVATE: return 3;
1909         case PROTECTED: return 1;
1910         default:
1911         case PUBLIC: return 0;
1912         case 0: return 2;
1913         }
1914     }
1915 
1916     /** A customized "cannot override" error message.
1917      *  @param m      The overriding method.
1918      *  @param other  The overridden method.
1919      *  @return       An internationalized string.
1920      */
1921     Fragment cannotOverride(MethodSymbol m, MethodSymbol other) {
1922         Symbol mloc = m.location();
1923         Symbol oloc = other.location();
1924 
1925         if ((other.owner.flags() & INTERFACE) == 0)
1926             return Fragments.CantOverride(m, mloc, other, oloc);
1927         else if ((m.owner.flags() & INTERFACE) == 0)
1928             return Fragments.CantImplement(m, mloc, other, oloc);
1929         else
1930             return Fragments.ClashesWith(m, mloc, other, oloc);
1931     }
1932 
1933     /** A customized "override" warning message.
1934      *  @param m      The overriding method.
1935      *  @param other  The overridden method.
1936      *  @return       An internationalized string.
1937      */
1938     Fragment uncheckedOverrides(MethodSymbol m, MethodSymbol other) {
1939         Symbol mloc = m.location();
1940         Symbol oloc = other.location();
1941 
1942         if ((other.owner.flags() & INTERFACE) == 0)
1943             return Fragments.UncheckedOverride(m, mloc, other, oloc);
1944         else if ((m.owner.flags() & INTERFACE) == 0)
1945             return Fragments.UncheckedImplement(m, mloc, other, oloc);
1946         else
1947             return Fragments.UncheckedClashWith(m, mloc, other, oloc);
1948     }
1949 
1950     /** A customized "override" warning message.
1951      *  @param m      The overriding method.
1952      *  @param other  The overridden method.
1953      *  @return       An internationalized string.
1954      */
1955     Fragment varargsOverrides(MethodSymbol m, MethodSymbol other) {
1956         Symbol mloc = m.location();
1957         Symbol oloc = other.location();
1958 
1959         if ((other.owner.flags() & INTERFACE) == 0)
1960             return Fragments.VarargsOverride(m, mloc, other, oloc);
1961         else  if ((m.owner.flags() & INTERFACE) == 0)
1962             return Fragments.VarargsImplement(m, mloc, other, oloc);
1963         else
1964             return Fragments.VarargsClashWith(m, mloc, other, oloc);
1965     }
1966 
1967     /** Check that this method conforms with overridden method 'other'.
1968      *  where `origin' is the class where checking started.
1969      *  Complications:
1970      *  (1) Do not check overriding of synthetic methods
1971      *      (reason: they might be final).
1972      *      todo: check whether this is still necessary.
1973      *  (2) Admit the case where an interface proxy throws fewer exceptions
1974      *      than the method it implements. Augment the proxy methods with the
1975      *      undeclared exceptions in this case.
1976      *  (3) When generics are enabled, admit the case where an interface proxy
1977      *      has a result type
1978      *      extended by the result type of the method it implements.
1979      *      Change the proxies result type to the smaller type in this case.
1980      *
1981      *  @param tree         The tree from which positions
1982      *                      are extracted for errors.
1983      *  @param m            The overriding method.
1984      *  @param other        The overridden method.
1985      *  @param origin       The class of which the overriding method
1986      *                      is a member.
1987      */
1988     void checkOverride(JCTree tree,
1989                        MethodSymbol m,
1990                        MethodSymbol other,
1991                        ClassSymbol origin) {
1992         // Don't check overriding of synthetic methods or by bridge methods.
1993         if ((m.flags() & (SYNTHETIC|BRIDGE)) != 0 || (other.flags() & SYNTHETIC) != 0) {
1994             return;
1995         }
1996 
1997         // Error if static method overrides instance method (JLS 8.4.8.2).
1998         if ((m.flags() & STATIC) != 0 &&
1999                    (other.flags() & STATIC) == 0) {
2000             log.error(TreeInfo.diagnosticPositionFor(m, tree),
2001                       Errors.OverrideStatic(cannotOverride(m, other)));
2002             m.flags_field |= BAD_OVERRIDE;
2003             return;
2004         }
2005 
2006         // Error if instance method overrides static or final
2007         // method (JLS 8.4.8.1).
2008         if ((other.flags() & FINAL) != 0 ||
2009                  (m.flags() & STATIC) == 0 &&
2010                  (other.flags() & STATIC) != 0) {
2011             log.error(TreeInfo.diagnosticPositionFor(m, tree),
2012                       Errors.OverrideMeth(cannotOverride(m, other),
2013                                           asFlagSet(other.flags() & (FINAL | STATIC))));
2014             m.flags_field |= BAD_OVERRIDE;
2015             return;
2016         }
2017 
2018         if ((m.owner.flags() & ANNOTATION) != 0) {
2019             // handled in validateAnnotationMethod
2020             return;
2021         }
2022 
2023         // Error if overriding method has weaker access (JLS 8.4.8.3).
2024         if (protection(m.flags()) > protection(other.flags())) {
2025             log.error(TreeInfo.diagnosticPositionFor(m, tree),
2026                       (other.flags() & AccessFlags) == 0 ?
2027                               Errors.OverrideWeakerAccess(cannotOverride(m, other),
2028                                                           "package") :
2029                               Errors.OverrideWeakerAccess(cannotOverride(m, other),
2030                                                           asFlagSet(other.flags() & AccessFlags)));
2031             m.flags_field |= BAD_OVERRIDE;
2032             return;
2033         }
2034 
2035         if (origin.isValueClass() && other.owner == syms.objectType.tsym && m.type.getParameterTypes().size() == 0) {
2036             if (m.name == names.finalize) {
2037                 log.error(TreeInfo.diagnosticPositionFor(m, tree),
2038                         Errors.ValueClassMayNotOverride(m.name));
2039                 m.flags_field |= BAD_OVERRIDE;
2040                 return;
2041             }
2042         }
2043 
2044         Type mt = types.memberType(origin.type, m);
2045         Type ot = types.memberType(origin.type, other);
2046         // Error if overriding result type is different
2047         // (or, in the case of generics mode, not a subtype) of
2048         // overridden result type. We have to rename any type parameters
2049         // before comparing types.
2050         List<Type> mtvars = mt.getTypeArguments();
2051         List<Type> otvars = ot.getTypeArguments();
2052         Type mtres = mt.getReturnType();
2053         Type otres = types.subst(ot.getReturnType(), otvars, mtvars);
2054 
2055         overrideWarner.clear();
2056         boolean resultTypesOK =
2057             types.returnTypeSubstitutable(mt, ot, otres, overrideWarner);
2058         if (!resultTypesOK) {
2059             if ((m.flags() & STATIC) != 0 && (other.flags() & STATIC) != 0) {
2060                 log.error(TreeInfo.diagnosticPositionFor(m, tree),
2061                           Errors.OverrideIncompatibleRet(Fragments.CantHide(m, m.location(), other,
2062                                         other.location()), mtres, otres));
2063                 m.flags_field |= BAD_OVERRIDE;
2064             } else {
2065                 log.error(TreeInfo.diagnosticPositionFor(m, tree),
2066                           Errors.OverrideIncompatibleRet(cannotOverride(m, other), mtres, otres));
2067                 m.flags_field |= BAD_OVERRIDE;
2068             }
2069             return;
2070         } else if (overrideWarner.hasNonSilentLint(LintCategory.UNCHECKED)) {
2071             warnUnchecked(TreeInfo.diagnosticPositionFor(m, tree),
2072                     Warnings.OverrideUncheckedRet(uncheckedOverrides(m, other), mtres, otres));
2073         }
2074 
2075         // Error if overriding method throws an exception not reported
2076         // by overridden method.
2077         List<Type> otthrown = types.subst(ot.getThrownTypes(), otvars, mtvars);
2078         List<Type> unhandledErased = unhandled(mt.getThrownTypes(), types.erasure(otthrown));
2079         List<Type> unhandledUnerased = unhandled(mt.getThrownTypes(), otthrown);
2080         if (unhandledErased.nonEmpty()) {
2081             log.error(TreeInfo.diagnosticPositionFor(m, tree),
2082                       Errors.OverrideMethDoesntThrow(cannotOverride(m, other), unhandledUnerased.head));
2083             m.flags_field |= BAD_OVERRIDE;
2084             return;
2085         }
2086         else if (unhandledUnerased.nonEmpty()) {
2087             warnUnchecked(TreeInfo.diagnosticPositionFor(m, tree),
2088                           Warnings.OverrideUncheckedThrown(cannotOverride(m, other), unhandledUnerased.head));
2089             return;
2090         }
2091 
2092         // Optional warning if varargs don't agree
2093         if ((((m.flags() ^ other.flags()) & Flags.VARARGS) != 0)
2094             && lint.isEnabled(LintCategory.OVERRIDES)) {
2095             log.warning(TreeInfo.diagnosticPositionFor(m, tree),
2096                         ((m.flags() & Flags.VARARGS) != 0)
2097                         ? Warnings.OverrideVarargsMissing(varargsOverrides(m, other))
2098                         : Warnings.OverrideVarargsExtra(varargsOverrides(m, other)));
2099         }
2100 
2101         // Warn if instance method overrides bridge method (compiler spec ??)
2102         if ((other.flags() & BRIDGE) != 0) {
2103             log.warning(TreeInfo.diagnosticPositionFor(m, tree),
2104                         Warnings.OverrideBridge(uncheckedOverrides(m, other)));
2105         }
2106 
2107         // Warn if a deprecated method overridden by a non-deprecated one.
2108         if (!isDeprecatedOverrideIgnorable(other, origin)) {
2109             Lint prevLint = setLint(lint.augment(m));
2110             try {
2111                 checkDeprecated(() -> TreeInfo.diagnosticPositionFor(m, tree), m, other);
2112             } finally {
2113                 setLint(prevLint);
2114             }
2115         }
2116     }
2117     // where
2118         private boolean isDeprecatedOverrideIgnorable(MethodSymbol m, ClassSymbol origin) {
2119             // If the method, m, is defined in an interface, then ignore the issue if the method
2120             // is only inherited via a supertype and also implemented in the supertype,
2121             // because in that case, we will rediscover the issue when examining the method
2122             // in the supertype.
2123             // If the method, m, is not defined in an interface, then the only time we need to
2124             // address the issue is when the method is the supertype implementation: any other
2125             // case, we will have dealt with when examining the supertype classes
2126             ClassSymbol mc = m.enclClass();
2127             Type st = types.supertype(origin.type);
2128             if (!st.hasTag(CLASS))
2129                 return true;
2130             MethodSymbol stimpl = m.implementation((ClassSymbol)st.tsym, types, false);
2131 
2132             if (mc != null && ((mc.flags() & INTERFACE) != 0)) {
2133                 List<Type> intfs = types.interfaces(origin.type);
2134                 return (intfs.contains(mc.type) ? false : (stimpl != null));
2135             }
2136             else
2137                 return (stimpl != m);
2138         }
2139 
2140 
2141     // used to check if there were any unchecked conversions
2142     Warner overrideWarner = new Warner();
2143 
2144     /** Check that a class does not inherit two concrete methods
2145      *  with the same signature.
2146      *  @param pos          Position to be used for error reporting.
2147      *  @param site         The class type to be checked.
2148      */
2149     public void checkCompatibleConcretes(DiagnosticPosition pos, Type site) {
2150         Type sup = types.supertype(site);
2151         if (!sup.hasTag(CLASS)) return;
2152 
2153         for (Type t1 = sup;
2154              t1.hasTag(CLASS) && t1.tsym.type.isParameterized();
2155              t1 = types.supertype(t1)) {
2156             for (Symbol s1 : t1.tsym.members().getSymbols(NON_RECURSIVE)) {
2157                 if (s1.kind != MTH ||
2158                     (s1.flags() & (STATIC|SYNTHETIC|BRIDGE)) != 0 ||
2159                     !s1.isInheritedIn(site.tsym, types) ||
2160                     ((MethodSymbol)s1).implementation(site.tsym,
2161                                                       types,
2162                                                       true) != s1)
2163                     continue;
2164                 Type st1 = types.memberType(t1, s1);
2165                 int s1ArgsLength = st1.getParameterTypes().length();
2166                 if (st1 == s1.type) continue;
2167 
2168                 for (Type t2 = sup;
2169                      t2.hasTag(CLASS);
2170                      t2 = types.supertype(t2)) {
2171                     for (Symbol s2 : t2.tsym.members().getSymbolsByName(s1.name)) {
2172                         if (s2 == s1 ||
2173                             s2.kind != MTH ||
2174                             (s2.flags() & (STATIC|SYNTHETIC|BRIDGE)) != 0 ||
2175                             s2.type.getParameterTypes().length() != s1ArgsLength ||
2176                             !s2.isInheritedIn(site.tsym, types) ||
2177                             ((MethodSymbol)s2).implementation(site.tsym,
2178                                                               types,
2179                                                               true) != s2)
2180                             continue;
2181                         Type st2 = types.memberType(t2, s2);
2182                         if (types.overrideEquivalent(st1, st2))
2183                             log.error(pos,
2184                                       Errors.ConcreteInheritanceConflict(s1, t1, s2, t2, sup));
2185                     }
2186                 }
2187             }
2188         }
2189     }
2190 
2191     /** Check that classes (or interfaces) do not each define an abstract
2192      *  method with same name and arguments but incompatible return types.
2193      *  @param pos          Position to be used for error reporting.
2194      *  @param t1           The first argument type.
2195      *  @param t2           The second argument type.
2196      */
2197     public boolean checkCompatibleAbstracts(DiagnosticPosition pos,
2198                                             Type t1,
2199                                             Type t2,
2200                                             Type site) {
2201         if ((site.tsym.flags() & COMPOUND) != 0) {
2202             // special case for intersections: need to eliminate wildcards in supertypes
2203             t1 = types.capture(t1);
2204             t2 = types.capture(t2);
2205         }
2206         return firstIncompatibility(pos, t1, t2, site) == null;
2207     }
2208 
2209     /** Return the first method which is defined with same args
2210      *  but different return types in two given interfaces, or null if none
2211      *  exists.
2212      *  @param t1     The first type.
2213      *  @param t2     The second type.
2214      *  @param site   The most derived type.
2215      *  @return symbol from t2 that conflicts with one in t1.
2216      */
2217     private Symbol firstIncompatibility(DiagnosticPosition pos, Type t1, Type t2, Type site) {
2218         Map<TypeSymbol,Type> interfaces1 = new HashMap<>();
2219         closure(t1, interfaces1);
2220         Map<TypeSymbol,Type> interfaces2;
2221         if (t1 == t2)
2222             interfaces2 = interfaces1;
2223         else
2224             closure(t2, interfaces1, interfaces2 = new HashMap<>());
2225 
2226         for (Type t3 : interfaces1.values()) {
2227             for (Type t4 : interfaces2.values()) {
2228                 Symbol s = firstDirectIncompatibility(pos, t3, t4, site);
2229                 if (s != null) return s;
2230             }
2231         }
2232         return null;
2233     }
2234 
2235     /** Compute all the supertypes of t, indexed by type symbol. */
2236     private void closure(Type t, Map<TypeSymbol,Type> typeMap) {
2237         if (!t.hasTag(CLASS)) return;
2238         if (typeMap.put(t.tsym, t) == null) {
2239             closure(types.supertype(t), typeMap);
2240             for (Type i : types.interfaces(t))
2241                 closure(i, typeMap);
2242         }
2243     }
2244 
2245     /** Compute all the supertypes of t, indexed by type symbol (except those in typesSkip). */
2246     private void closure(Type t, Map<TypeSymbol,Type> typesSkip, Map<TypeSymbol,Type> typeMap) {
2247         if (!t.hasTag(CLASS)) return;
2248         if (typesSkip.get(t.tsym) != null) return;
2249         if (typeMap.put(t.tsym, t) == null) {
2250             closure(types.supertype(t), typesSkip, typeMap);
2251             for (Type i : types.interfaces(t))
2252                 closure(i, typesSkip, typeMap);
2253         }
2254     }
2255 
2256     /** Return the first method in t2 that conflicts with a method from t1. */
2257     private Symbol firstDirectIncompatibility(DiagnosticPosition pos, Type t1, Type t2, Type site) {
2258         for (Symbol s1 : t1.tsym.members().getSymbols(NON_RECURSIVE)) {
2259             Type st1 = null;
2260             if (s1.kind != MTH || !s1.isInheritedIn(site.tsym, types) ||
2261                     (s1.flags() & SYNTHETIC) != 0) continue;
2262             Symbol impl = ((MethodSymbol)s1).implementation(site.tsym, types, false);
2263             if (impl != null && (impl.flags() & ABSTRACT) == 0) continue;
2264             for (Symbol s2 : t2.tsym.members().getSymbolsByName(s1.name)) {
2265                 if (s1 == s2) continue;
2266                 if (s2.kind != MTH || !s2.isInheritedIn(site.tsym, types) ||
2267                         (s2.flags() & SYNTHETIC) != 0) continue;
2268                 if (st1 == null) st1 = types.memberType(t1, s1);
2269                 Type st2 = types.memberType(t2, s2);
2270                 if (types.overrideEquivalent(st1, st2)) {
2271                     List<Type> tvars1 = st1.getTypeArguments();
2272                     List<Type> tvars2 = st2.getTypeArguments();
2273                     Type rt1 = st1.getReturnType();
2274                     Type rt2 = types.subst(st2.getReturnType(), tvars2, tvars1);
2275                     boolean compat =
2276                         types.isSameType(rt1, rt2) ||
2277                         !rt1.isPrimitiveOrVoid() &&
2278                         !rt2.isPrimitiveOrVoid() &&
2279                         (types.covariantReturnType(rt1, rt2, types.noWarnings) ||
2280                          types.covariantReturnType(rt2, rt1, types.noWarnings)) ||
2281                          checkCommonOverriderIn(s1,s2,site);
2282                     if (!compat) {
2283                         log.error(pos, Errors.TypesIncompatible(t1, t2,
2284                                 Fragments.IncompatibleDiffRet(s2.name, types.memberType(t2, s2).getParameterTypes())));
2285                         return s2;
2286                     }
2287                 } else if (checkNameClash((ClassSymbol)site.tsym, s1, s2) &&
2288                         !checkCommonOverriderIn(s1, s2, site)) {
2289                     log.error(pos, Errors.NameClashSameErasureNoOverride(
2290                             s1.name, types.memberType(site, s1).asMethodType().getParameterTypes(), s1.location(),
2291                             s2.name, types.memberType(site, s2).asMethodType().getParameterTypes(), s2.location()));
2292                     return s2;
2293                 }
2294             }
2295         }
2296         return null;
2297     }
2298     //WHERE
2299     boolean checkCommonOverriderIn(Symbol s1, Symbol s2, Type site) {
2300         Map<TypeSymbol,Type> supertypes = new HashMap<>();
2301         Type st1 = types.memberType(site, s1);
2302         Type st2 = types.memberType(site, s2);
2303         closure(site, supertypes);
2304         for (Type t : supertypes.values()) {
2305             for (Symbol s3 : t.tsym.members().getSymbolsByName(s1.name)) {
2306                 if (s3 == s1 || s3 == s2 || s3.kind != MTH || (s3.flags() & (BRIDGE|SYNTHETIC)) != 0) continue;
2307                 Type st3 = types.memberType(site,s3);
2308                 if (types.overrideEquivalent(st3, st1) &&
2309                         types.overrideEquivalent(st3, st2) &&
2310                         types.returnTypeSubstitutable(st3, st1) &&
2311                         types.returnTypeSubstitutable(st3, st2)) {
2312                     return true;
2313                 }
2314             }
2315         }
2316         return false;
2317     }
2318 
2319     /** Check that a given method conforms with any method it overrides.
2320      *  @param tree         The tree from which positions are extracted
2321      *                      for errors.
2322      *  @param m            The overriding method.
2323      */
2324     void checkOverride(Env<AttrContext> env, JCMethodDecl tree, MethodSymbol m) {
2325         ClassSymbol origin = (ClassSymbol)m.owner;
2326         if ((origin.flags() & ENUM) != 0 && names.finalize.equals(m.name)) {
2327             if (m.overrides(syms.enumFinalFinalize, origin, types, false)) {
2328                 log.error(tree.pos(), Errors.EnumNoFinalize);
2329                 return;
2330             }
2331         }
2332         if (allowRecords && origin.isRecord()) {
2333             // let's find out if this is a user defined accessor in which case the @Override annotation is acceptable
2334             Optional<? extends RecordComponent> recordComponent = origin.getRecordComponents().stream()
2335                     .filter(rc -> rc.accessor == tree.sym && (rc.accessor.flags_field & GENERATED_MEMBER) == 0).findFirst();
2336             if (recordComponent.isPresent()) {
2337                 return;
2338             }
2339         }
2340 
2341         for (Type t = origin.type; t.hasTag(CLASS);
2342              t = types.supertype(t)) {
2343             if (t != origin.type) {
2344                 checkOverride(tree, t, origin, m);
2345             }
2346             for (Type t2 : types.interfaces(t)) {
2347                 checkOverride(tree, t2, origin, m);
2348             }
2349         }
2350 
2351         final boolean explicitOverride = m.attribute(syms.overrideType.tsym) != null;
2352         // Check if this method must override a super method due to being annotated with @Override
2353         // or by virtue of being a member of a diamond inferred anonymous class. Latter case is to
2354         // be treated "as if as they were annotated" with @Override.
2355         boolean mustOverride = explicitOverride ||
2356                 (env.info.isAnonymousDiamond && !m.isConstructor() && !m.isPrivate());
2357         if (mustOverride && !isOverrider(m)) {
2358             DiagnosticPosition pos = tree.pos();
2359             for (JCAnnotation a : tree.getModifiers().annotations) {
2360                 if (a.annotationType.type.tsym == syms.overrideType.tsym) {
2361                     pos = a.pos();
2362                     break;
2363                 }
2364             }
2365             log.error(pos,
2366                       explicitOverride ? (m.isStatic() ? Errors.StaticMethodsCannotBeAnnotatedWithOverride : Errors.MethodDoesNotOverrideSuperclass) :
2367                                 Errors.AnonymousDiamondMethodDoesNotOverrideSuperclass(Fragments.DiamondAnonymousMethodsImplicitlyOverride));
2368         }
2369     }
2370 
2371     void checkOverride(JCTree tree, Type site, ClassSymbol origin, MethodSymbol m) {
2372         TypeSymbol c = site.tsym;
2373         for (Symbol sym : c.members().getSymbolsByName(m.name)) {
2374             if (m.overrides(sym, origin, types, false)) {
2375                 if ((sym.flags() & ABSTRACT) == 0) {
2376                     checkOverride(tree, m, (MethodSymbol)sym, origin);
2377                 }
2378             }
2379         }
2380     }
2381 
2382     private Predicate<Symbol> equalsHasCodeFilter = s -> MethodSymbol.implementation_filter.test(s) &&
2383             (s.flags() & BAD_OVERRIDE) == 0;
2384 
2385     public void checkClassOverrideEqualsAndHashIfNeeded(DiagnosticPosition pos,
2386             ClassSymbol someClass) {
2387         /* At present, annotations cannot possibly have a method that is override
2388          * equivalent with Object.equals(Object) but in any case the condition is
2389          * fine for completeness.
2390          */
2391         if (someClass == (ClassSymbol)syms.objectType.tsym ||
2392             someClass.isInterface() || someClass.isEnum() ||
2393             (someClass.flags() & ANNOTATION) != 0 ||
2394             (someClass.flags() & ABSTRACT) != 0) return;
2395         //anonymous inner classes implementing interfaces need especial treatment
2396         if (someClass.isAnonymous()) {
2397             List<Type> interfaces =  types.interfaces(someClass.type);
2398             if (interfaces != null && !interfaces.isEmpty() &&
2399                 interfaces.head.tsym == syms.comparatorType.tsym) return;
2400         }
2401         checkClassOverrideEqualsAndHash(pos, someClass);
2402     }
2403 
2404     private void checkClassOverrideEqualsAndHash(DiagnosticPosition pos,
2405             ClassSymbol someClass) {
2406         if (lint.isEnabled(LintCategory.OVERRIDES)) {
2407             MethodSymbol equalsAtObject = (MethodSymbol)syms.objectType
2408                     .tsym.members().findFirst(names.equals);
2409             MethodSymbol hashCodeAtObject = (MethodSymbol)syms.objectType
2410                     .tsym.members().findFirst(names.hashCode);
2411             MethodSymbol equalsImpl = types.implementation(equalsAtObject,
2412                     someClass, false, equalsHasCodeFilter);
2413             boolean overridesEquals = equalsImpl != null &&
2414                                       equalsImpl.owner == someClass;
2415             boolean overridesHashCode = types.implementation(hashCodeAtObject,
2416                 someClass, false, equalsHasCodeFilter) != hashCodeAtObject;
2417 
2418             if (overridesEquals && !overridesHashCode) {
2419                 log.warning(LintCategory.OVERRIDES, pos,
2420                             Warnings.OverrideEqualsButNotHashcode(someClass));
2421             }
2422         }
2423     }
2424 
2425     public void checkModuleName (JCModuleDecl tree) {
2426         Name moduleName = tree.sym.name;
2427         Assert.checkNonNull(moduleName);
2428         if (lint.isEnabled(LintCategory.MODULE)) {
2429             JCExpression qualId = tree.qualId;
2430             while (qualId != null) {
2431                 Name componentName;
2432                 DiagnosticPosition pos;
2433                 switch (qualId.getTag()) {
2434                     case SELECT:
2435                         JCFieldAccess selectNode = ((JCFieldAccess) qualId);
2436                         componentName = selectNode.name;
2437                         pos = selectNode.pos();
2438                         qualId = selectNode.selected;
2439                         break;
2440                     case IDENT:
2441                         componentName = ((JCIdent) qualId).name;
2442                         pos = qualId.pos();
2443                         qualId = null;
2444                         break;
2445                     default:
2446                         throw new AssertionError("Unexpected qualified identifier: " + qualId.toString());
2447                 }
2448                 if (componentName != null) {
2449                     String moduleNameComponentString = componentName.toString();
2450                     int nameLength = moduleNameComponentString.length();
2451                     if (nameLength > 0 && Character.isDigit(moduleNameComponentString.charAt(nameLength - 1))) {
2452                         log.warning(Lint.LintCategory.MODULE, pos, Warnings.PoorChoiceForModuleName(componentName));
2453                     }
2454                 }
2455             }
2456         }
2457     }
2458 
2459     private boolean checkNameClash(ClassSymbol origin, Symbol s1, Symbol s2) {
2460         ClashFilter cf = new ClashFilter(origin.type);
2461         return (cf.test(s1) &&
2462                 cf.test(s2) &&
2463                 types.hasSameArgs(s1.erasure(types), s2.erasure(types)));
2464     }
2465 
2466 
2467     /** Check that all abstract members of given class have definitions.
2468      *  @param pos          Position to be used for error reporting.
2469      *  @param c            The class.
2470      */
2471     void checkAllDefined(DiagnosticPosition pos, ClassSymbol c) {
2472         MethodSymbol undef = types.firstUnimplementedAbstract(c);
2473         if (undef != null) {
2474             MethodSymbol undef1 =
2475                 new MethodSymbol(undef.flags(), undef.name,
2476                                  types.memberType(c.type, undef), undef.owner);
2477             log.error(pos,
2478                       Errors.DoesNotOverrideAbstract(c, undef1, undef1.location()));
2479         }
2480     }
2481 
2482     // A primitive class cannot contain a field of its own type either or indirectly.
2483     void checkNonCyclicMembership(JCClassDecl tree) {
2484         Assert.check((tree.sym.flags_field & LOCKED) == 0);
2485         try {
2486             tree.sym.flags_field |= LOCKED;
2487             for (List<? extends JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
2488                 if (l.head.hasTag(VARDEF)) {
2489                     JCVariableDecl field = (JCVariableDecl) l.head;
2490                     if (cyclePossible(field.sym)) {
2491                         checkNonCyclicMembership((ClassSymbol) field.type.tsym, field.pos());
2492                     }
2493                 }
2494             }
2495         } finally {
2496             tree.sym.flags_field &= ~LOCKED;
2497         }
2498 
2499     }
2500     // where
2501     private void checkNonCyclicMembership(ClassSymbol c, DiagnosticPosition pos) {
2502         if ((c.flags_field & LOCKED) != 0) {
2503             log.error(pos, Errors.CyclicPrimitiveClassMembership(c));
2504             return;
2505         }
2506         try {
2507             c.flags_field |= LOCKED;
2508             for (Symbol fld : c.members().getSymbols(s -> s.kind == VAR && cyclePossible((VarSymbol) s), NON_RECURSIVE)) {
2509                 checkNonCyclicMembership((ClassSymbol) fld.type.tsym, pos);
2510             }
2511         } finally {
2512             c.flags_field &= ~LOCKED;
2513         }
2514     }
2515         // where
2516         private boolean cyclePossible(VarSymbol symbol) {
2517             return (symbol.flags() & STATIC) == 0 && symbol.type.isPrimitiveClass();
2518         }
2519 
2520     void checkNonCyclicDecl(JCClassDecl tree) {
2521         CycleChecker cc = new CycleChecker();
2522         cc.scan(tree);
2523         if (!cc.errorFound && !cc.partialCheck) {
2524             tree.sym.flags_field |= ACYCLIC;
2525         }
2526     }
2527 
2528     class CycleChecker extends TreeScanner {
2529 
2530         Set<Symbol> seenClasses = new HashSet<>();
2531         boolean errorFound = false;
2532         boolean partialCheck = false;
2533 
2534         private void checkSymbol(DiagnosticPosition pos, Symbol sym) {
2535             if (sym != null && sym.kind == TYP) {
2536                 Env<AttrContext> classEnv = enter.getEnv((TypeSymbol)sym);
2537                 if (classEnv != null) {
2538                     DiagnosticSource prevSource = log.currentSource();
2539                     try {
2540                         log.useSource(classEnv.toplevel.sourcefile);
2541                         scan(classEnv.tree);
2542                     }
2543                     finally {
2544                         log.useSource(prevSource.getFile());
2545                     }
2546                 } else if (sym.kind == TYP) {
2547                     checkClass(pos, sym, List.nil());
2548                 }
2549             } else if (sym == null || sym.kind != PCK) {
2550                 //not completed yet
2551                 partialCheck = true;
2552             }
2553         }
2554 
2555         @Override
2556         public void visitSelect(JCFieldAccess tree) {
2557             super.visitSelect(tree);
2558             checkSymbol(tree.pos(), tree.sym);
2559         }
2560 
2561         @Override
2562         public void visitIdent(JCIdent tree) {
2563             checkSymbol(tree.pos(), tree.sym);
2564         }
2565 
2566         @Override
2567         public void visitTypeApply(JCTypeApply tree) {
2568             scan(tree.clazz);
2569         }
2570 
2571         @Override
2572         public void visitTypeArray(JCArrayTypeTree tree) {
2573             scan(tree.elemtype);
2574         }
2575 
2576         @Override
2577         public void visitClassDef(JCClassDecl tree) {
2578             List<JCTree> supertypes = List.nil();
2579             if (tree.getExtendsClause() != null) {
2580                 supertypes = supertypes.prepend(tree.getExtendsClause());
2581             }
2582             if (tree.getImplementsClause() != null) {
2583                 for (JCTree intf : tree.getImplementsClause()) {
2584                     supertypes = supertypes.prepend(intf);
2585                 }
2586             }
2587             checkClass(tree.pos(), tree.sym, supertypes);
2588         }
2589 
2590         void checkClass(DiagnosticPosition pos, Symbol c, List<JCTree> supertypes) {
2591             if ((c.flags_field & ACYCLIC) != 0)
2592                 return;
2593             if (seenClasses.contains(c)) {
2594                 errorFound = true;
2595                 noteCyclic(pos, (ClassSymbol)c);
2596             } else if (!c.type.isErroneous()) {
2597                 try {
2598                     seenClasses.add(c);
2599                     if (c.type.hasTag(CLASS)) {
2600                         if (supertypes.nonEmpty()) {
2601                             scan(supertypes);
2602                         }
2603                         else {
2604                             ClassType ct = (ClassType)c.type;
2605                             if (ct.supertype_field == null ||
2606                                     ct.interfaces_field == null) {
2607                                 //not completed yet
2608                                 partialCheck = true;
2609                                 return;
2610                             }
2611                             checkSymbol(pos, ct.supertype_field.tsym);
2612                             for (Type intf : ct.interfaces_field) {
2613                                 checkSymbol(pos, intf.tsym);
2614                             }
2615                         }
2616                         if (c.owner.kind == TYP) {
2617                             checkSymbol(pos, c.owner);
2618                         }
2619                     }
2620                 } finally {
2621                     seenClasses.remove(c);
2622                 }
2623             }
2624         }
2625     }
2626 
2627     /** Check for cyclic references. Issue an error if the
2628      *  symbol of the type referred to has a LOCKED flag set.
2629      *
2630      *  @param pos      Position to be used for error reporting.
2631      *  @param t        The type referred to.
2632      */
2633     void checkNonCyclic(DiagnosticPosition pos, Type t) {
2634         checkNonCyclicInternal(pos, t);
2635     }
2636 
2637 
2638     void checkNonCyclic(DiagnosticPosition pos, TypeVar t) {
2639         checkNonCyclic1(pos, t, List.nil());
2640     }
2641 
2642     private void checkNonCyclic1(DiagnosticPosition pos, Type t, List<TypeVar> seen) {
2643         final TypeVar tv;
2644         if  (t.hasTag(TYPEVAR) && (t.tsym.flags() & UNATTRIBUTED) != 0)
2645             return;
2646         if (seen.contains(t)) {
2647             tv = (TypeVar)t;
2648             tv.setUpperBound(types.createErrorType(t));
2649             log.error(pos, Errors.CyclicInheritance(t));
2650         } else if (t.hasTag(TYPEVAR)) {
2651             tv = (TypeVar)t;
2652             seen = seen.prepend(tv);
2653             for (Type b : types.getBounds(tv))
2654                 checkNonCyclic1(pos, b, seen);
2655         }
2656     }
2657 
2658     /** Check for cyclic references. Issue an error if the
2659      *  symbol of the type referred to has a LOCKED flag set.
2660      *
2661      *  @param pos      Position to be used for error reporting.
2662      *  @param t        The type referred to.
2663      *  @returns        True if the check completed on all attributed classes
2664      */
2665     private boolean checkNonCyclicInternal(DiagnosticPosition pos, Type t) {
2666         boolean complete = true; // was the check complete?
2667         //- System.err.println("checkNonCyclicInternal("+t+");");//DEBUG
2668         Symbol c = t.tsym;
2669         if ((c.flags_field & ACYCLIC) != 0) return true;
2670 
2671         if ((c.flags_field & LOCKED) != 0) {
2672             noteCyclic(pos, (ClassSymbol)c);
2673         } else if (!c.type.isErroneous()) {
2674             try {
2675                 c.flags_field |= LOCKED;
2676                 if (c.type.hasTag(CLASS)) {
2677                     ClassType clazz = (ClassType)c.type;
2678                     if (clazz.interfaces_field != null)
2679                         for (List<Type> l=clazz.interfaces_field; l.nonEmpty(); l=l.tail)
2680                             complete &= checkNonCyclicInternal(pos, l.head);
2681                     if (clazz.supertype_field != null) {
2682                         Type st = clazz.supertype_field;
2683                         if (st != null && st.hasTag(CLASS))
2684                             complete &= checkNonCyclicInternal(pos, st);
2685                     }
2686                     if (c.owner.kind == TYP)
2687                         complete &= checkNonCyclicInternal(pos, c.owner.type);
2688                 }
2689             } finally {
2690                 c.flags_field &= ~LOCKED;
2691             }
2692         }
2693         if (complete)
2694             complete = ((c.flags_field & UNATTRIBUTED) == 0) && c.isCompleted();
2695         if (complete) c.flags_field |= ACYCLIC;
2696         return complete;
2697     }
2698 
2699     /** Note that we found an inheritance cycle. */
2700     private void noteCyclic(DiagnosticPosition pos, ClassSymbol c) {
2701         log.error(pos, Errors.CyclicInheritance(c));
2702         for (List<Type> l=types.interfaces(c.type); l.nonEmpty(); l=l.tail)
2703             l.head = types.createErrorType((ClassSymbol)l.head.tsym, Type.noType);
2704         Type st = types.supertype(c.type);
2705         if (st.hasTag(CLASS))
2706             ((ClassType)c.type).supertype_field = types.createErrorType((ClassSymbol)st.tsym, Type.noType);
2707         c.type = types.createErrorType(c, c.type);
2708         c.flags_field |= ACYCLIC;
2709     }
2710 
2711     /** Check that all methods which implement some
2712      *  method conform to the method they implement.
2713      *  @param tree         The class definition whose members are checked.
2714      */
2715     void checkImplementations(JCClassDecl tree) {
2716         checkImplementations(tree, tree.sym, tree.sym);
2717     }
2718     //where
2719         /** Check that all methods which implement some
2720          *  method in `ic' conform to the method they implement.
2721          */
2722         void checkImplementations(JCTree tree, ClassSymbol origin, ClassSymbol ic) {
2723             for (List<Type> l = types.closure(ic.type); l.nonEmpty(); l = l.tail) {
2724                 ClassSymbol lc = (ClassSymbol)l.head.tsym;
2725                 if ((lc.flags() & ABSTRACT) != 0) {
2726                     for (Symbol sym : lc.members().getSymbols(NON_RECURSIVE)) {
2727                         if (sym.kind == MTH &&
2728                             (sym.flags() & (STATIC|ABSTRACT)) == ABSTRACT) {
2729                             MethodSymbol absmeth = (MethodSymbol)sym;
2730                             MethodSymbol implmeth = absmeth.implementation(origin, types, false);
2731                             if (implmeth != null && implmeth != absmeth &&
2732                                 (implmeth.owner.flags() & INTERFACE) ==
2733                                 (origin.flags() & INTERFACE)) {
2734                                 // don't check if implmeth is in a class, yet
2735                                 // origin is an interface. This case arises only
2736                                 // if implmeth is declared in Object. The reason is
2737                                 // that interfaces really don't inherit from
2738                                 // Object it's just that the compiler represents
2739                                 // things that way.
2740                                 checkOverride(tree, implmeth, absmeth, origin);
2741                             }
2742                         }
2743                     }
2744                 }
2745             }
2746         }
2747 
2748     /** Check that all abstract methods implemented by a class are
2749      *  mutually compatible.
2750      *  @param pos          Position to be used for error reporting.
2751      *  @param c            The class whose interfaces are checked.
2752      */
2753     void checkCompatibleSupertypes(DiagnosticPosition pos, Type c) {
2754         List<Type> supertypes = types.interfaces(c);
2755         Type supertype = types.supertype(c);
2756         if (supertype.hasTag(CLASS) &&
2757             (supertype.tsym.flags() & ABSTRACT) != 0)
2758             supertypes = supertypes.prepend(supertype);
2759         for (List<Type> l = supertypes; l.nonEmpty(); l = l.tail) {
2760             if (!l.head.getTypeArguments().isEmpty() &&
2761                 !checkCompatibleAbstracts(pos, l.head, l.head, c))
2762                 return;
2763             for (List<Type> m = supertypes; m != l; m = m.tail)
2764                 if (!checkCompatibleAbstracts(pos, l.head, m.head, c))
2765                     return;
2766         }
2767         checkCompatibleConcretes(pos, c);
2768 
2769         boolean cIsValue = (c.tsym.flags() & VALUE_CLASS) != 0;
2770         boolean cHasIdentity = (c.tsym.flags() & IDENTITY_TYPE) != 0;
2771         Type identitySuper = null, valueSuper = null;
2772         for (Type t : types.closure(c)) {
2773             if (t != c) {
2774                 if ((t.tsym.flags() & IDENTITY_TYPE) != 0)
2775                     identitySuper = t;
2776                 else if ((t.tsym.flags() & VALUE_CLASS) != 0)
2777                     valueSuper = t;
2778                 if (cIsValue &&  identitySuper != null) {
2779                     log.error(pos, Errors.ValueTypeHasIdentitySuperType(c, identitySuper));
2780                     break;
2781                 } else if (cHasIdentity &&  valueSuper != null) {
2782                     log.error(pos, Errors.IdentityTypeHasValueSuperType(c, valueSuper));
2783                     break;
2784                 } else if (identitySuper != null && valueSuper != null) {
2785                     log.error(pos, Errors.MutuallyIncompatibleSupers(c, identitySuper, valueSuper));
2786                     break;
2787                 }
2788             }
2789         }
2790     }
2791 
2792     /** Check that all non-override equivalent methods accessible from 'site'
2793      *  are mutually compatible (JLS 8.4.8/9.4.1).
2794      *
2795      *  @param pos  Position to be used for error reporting.
2796      *  @param site The class whose methods are checked.
2797      *  @param sym  The method symbol to be checked.
2798      */
2799     void checkOverrideClashes(DiagnosticPosition pos, Type site, MethodSymbol sym) {
2800          ClashFilter cf = new ClashFilter(site);
2801         //for each method m1 that is overridden (directly or indirectly)
2802         //by method 'sym' in 'site'...
2803 
2804         List<MethodSymbol> potentiallyAmbiguousList = List.nil();
2805         boolean overridesAny = false;
2806         ArrayList<Symbol> symbolsByName = new ArrayList<>();
2807         types.membersClosure(site, false).getSymbolsByName(sym.name, cf).forEach(symbolsByName::add);
2808         for (Symbol m1 : symbolsByName) {
2809             if (!sym.overrides(m1, site.tsym, types, false)) {
2810                 if (m1 == sym) {
2811                     continue;
2812                 }
2813 
2814                 if (!overridesAny) {
2815                     potentiallyAmbiguousList = potentiallyAmbiguousList.prepend((MethodSymbol)m1);
2816                 }
2817                 continue;
2818             }
2819 
2820             if (m1 != sym) {
2821                 overridesAny = true;
2822                 potentiallyAmbiguousList = List.nil();
2823             }
2824 
2825             //...check each method m2 that is a member of 'site'
2826             for (Symbol m2 : symbolsByName) {
2827                 if (m2 == m1) continue;
2828                 //if (i) the signature of 'sym' is not a subsignature of m1 (seen as
2829                 //a member of 'site') and (ii) m1 has the same erasure as m2, issue an error
2830                 if (!types.isSubSignature(sym.type, types.memberType(site, m2), Feature.STRICT_METHOD_CLASH_CHECK.allowedInSource(source)) &&
2831                         types.hasSameArgs(m2.erasure(types), m1.erasure(types))) {
2832                     sym.flags_field |= CLASH;
2833                     if (m1 == sym) {
2834                         log.error(pos, Errors.NameClashSameErasureNoOverride(
2835                             m1.name, types.memberType(site, m1).asMethodType().getParameterTypes(), m1.location(),
2836                             m2.name, types.memberType(site, m2).asMethodType().getParameterTypes(), m2.location()));
2837                     } else {
2838                         ClassType ct = (ClassType)site;
2839                         String kind = ct.isInterface() ? "interface" : "class";
2840                         log.error(pos, Errors.NameClashSameErasureNoOverride1(
2841                             kind,
2842                             ct.tsym.name,
2843                             m1.name,
2844                             types.memberType(site, m1).asMethodType().getParameterTypes(),
2845                             m1.location(),
2846                             m2.name,
2847                             types.memberType(site, m2).asMethodType().getParameterTypes(),
2848                             m2.location()));
2849                     }
2850                     return;
2851                 }
2852             }
2853         }
2854 
2855         if (!overridesAny) {
2856             for (MethodSymbol m: potentiallyAmbiguousList) {
2857                 checkPotentiallyAmbiguousOverloads(pos, site, sym, m);
2858             }
2859         }
2860     }
2861 
2862     /** Check that all static methods accessible from 'site' are
2863      *  mutually compatible (JLS 8.4.8).
2864      *
2865      *  @param pos  Position to be used for error reporting.
2866      *  @param site The class whose methods are checked.
2867      *  @param sym  The method symbol to be checked.
2868      */
2869     void checkHideClashes(DiagnosticPosition pos, Type site, MethodSymbol sym) {
2870         ClashFilter cf = new ClashFilter(site);
2871         //for each method m1 that is a member of 'site'...
2872         for (Symbol s : types.membersClosure(site, true).getSymbolsByName(sym.name, cf)) {
2873             //if (i) the signature of 'sym' is not a subsignature of m1 (seen as
2874             //a member of 'site') and (ii) 'sym' has the same erasure as m1, issue an error
2875             if (!types.isSubSignature(sym.type, types.memberType(site, s), Feature.STRICT_METHOD_CLASH_CHECK.allowedInSource(source))) {
2876                 if (types.hasSameArgs(s.erasure(types), sym.erasure(types))) {
2877                     log.error(pos,
2878                               Errors.NameClashSameErasureNoHide(sym, sym.location(), s, s.location()));
2879                     return;
2880                 } else {
2881                     checkPotentiallyAmbiguousOverloads(pos, site, sym, (MethodSymbol)s);
2882                 }
2883             }
2884          }
2885      }
2886 
2887      //where
2888      private class ClashFilter implements Predicate<Symbol> {
2889 
2890          Type site;
2891 
2892          ClashFilter(Type site) {
2893              this.site = site;
2894          }
2895 
2896          boolean shouldSkip(Symbol s) {
2897              return (s.flags() & CLASH) != 0 &&
2898                 s.owner == site.tsym;
2899          }
2900 
2901          @Override
2902          public boolean test(Symbol s) {
2903              return s.kind == MTH &&
2904                      (s.flags() & SYNTHETIC) == 0 &&
2905                      !shouldSkip(s) &&
2906                      s.isInheritedIn(site.tsym, types) &&
2907                      !s.isConstructor();
2908          }
2909      }
2910 
2911     void checkDefaultMethodClashes(DiagnosticPosition pos, Type site) {
2912         DefaultMethodClashFilter dcf = new DefaultMethodClashFilter(site);
2913         for (Symbol m : types.membersClosure(site, false).getSymbols(dcf)) {
2914             Assert.check(m.kind == MTH);
2915             List<MethodSymbol> prov = types.interfaceCandidates(site, (MethodSymbol)m);
2916             if (prov.size() > 1) {
2917                 ListBuffer<Symbol> abstracts = new ListBuffer<>();
2918                 ListBuffer<Symbol> defaults = new ListBuffer<>();
2919                 for (MethodSymbol provSym : prov) {
2920                     if ((provSym.flags() & DEFAULT) != 0) {
2921                         defaults = defaults.append(provSym);
2922                     } else if ((provSym.flags() & ABSTRACT) != 0) {
2923                         abstracts = abstracts.append(provSym);
2924                     }
2925                     if (defaults.nonEmpty() && defaults.size() + abstracts.size() >= 2) {
2926                         //strong semantics - issue an error if two sibling interfaces
2927                         //have two override-equivalent defaults - or if one is abstract
2928                         //and the other is default
2929                         Fragment diagKey;
2930                         Symbol s1 = defaults.first();
2931                         Symbol s2;
2932                         if (defaults.size() > 1) {
2933                             s2 = defaults.toList().tail.head;
2934                             diagKey = Fragments.IncompatibleUnrelatedDefaults(Kinds.kindName(site.tsym), site,
2935                                     m.name, types.memberType(site, m).getParameterTypes(),
2936                                     s1.location(), s2.location());
2937 
2938                         } else {
2939                             s2 = abstracts.first();
2940                             diagKey = Fragments.IncompatibleAbstractDefault(Kinds.kindName(site.tsym), site,
2941                                     m.name, types.memberType(site, m).getParameterTypes(),
2942                                     s1.location(), s2.location());
2943                         }
2944                         log.error(pos, Errors.TypesIncompatible(s1.location().type, s2.location().type, diagKey));
2945                         break;
2946                     }
2947                 }
2948             }
2949         }
2950     }
2951 
2952     //where
2953      private class DefaultMethodClashFilter implements Predicate<Symbol> {
2954 
2955          Type site;
2956 
2957          DefaultMethodClashFilter(Type site) {
2958              this.site = site;
2959          }
2960 
2961          @Override
2962          public boolean test(Symbol s) {
2963              return s.kind == MTH &&
2964                      (s.flags() & DEFAULT) != 0 &&
2965                      s.isInheritedIn(site.tsym, types) &&
2966                      !s.isConstructor();
2967          }
2968      }
2969 
2970     /**
2971       * Report warnings for potentially ambiguous method declarations. Two declarations
2972       * are potentially ambiguous if they feature two unrelated functional interface
2973       * in same argument position (in which case, a call site passing an implicit
2974       * lambda would be ambiguous).
2975       */
2976     void checkPotentiallyAmbiguousOverloads(DiagnosticPosition pos, Type site,
2977             MethodSymbol msym1, MethodSymbol msym2) {
2978         if (msym1 != msym2 &&
2979                 Feature.DEFAULT_METHODS.allowedInSource(source) &&
2980                 lint.isEnabled(LintCategory.OVERLOADS) &&
2981                 (msym1.flags() & POTENTIALLY_AMBIGUOUS) == 0 &&
2982                 (msym2.flags() & POTENTIALLY_AMBIGUOUS) == 0) {
2983             Type mt1 = types.memberType(site, msym1);
2984             Type mt2 = types.memberType(site, msym2);
2985             //if both generic methods, adjust type variables
2986             if (mt1.hasTag(FORALL) && mt2.hasTag(FORALL) &&
2987                     types.hasSameBounds((ForAll)mt1, (ForAll)mt2)) {
2988                 mt2 = types.subst(mt2, ((ForAll)mt2).tvars, ((ForAll)mt1).tvars);
2989             }
2990             //expand varargs methods if needed
2991             int maxLength = Math.max(mt1.getParameterTypes().length(), mt2.getParameterTypes().length());
2992             List<Type> args1 = rs.adjustArgs(mt1.getParameterTypes(), msym1, maxLength, true);
2993             List<Type> args2 = rs.adjustArgs(mt2.getParameterTypes(), msym2, maxLength, true);
2994             //if arities don't match, exit
2995             if (args1.length() != args2.length()) return;
2996             boolean potentiallyAmbiguous = false;
2997             while (args1.nonEmpty() && args2.nonEmpty()) {
2998                 Type s = args1.head;
2999                 Type t = args2.head;
3000                 if (!types.isSubtype(t, s) && !types.isSubtype(s, t)) {
3001                     if (types.isFunctionalInterface(s) && types.isFunctionalInterface(t) &&
3002                             types.findDescriptorType(s).getParameterTypes().length() > 0 &&
3003                             types.findDescriptorType(s).getParameterTypes().length() ==
3004                             types.findDescriptorType(t).getParameterTypes().length()) {
3005                         potentiallyAmbiguous = true;
3006                     } else {
3007                         return;
3008                     }
3009                 }
3010                 args1 = args1.tail;
3011                 args2 = args2.tail;
3012             }
3013             if (potentiallyAmbiguous) {
3014                 //we found two incompatible functional interfaces with same arity
3015                 //this means a call site passing an implicit lambda would be ambiguous
3016                 msym1.flags_field |= POTENTIALLY_AMBIGUOUS;
3017                 msym2.flags_field |= POTENTIALLY_AMBIGUOUS;
3018                 log.warning(LintCategory.OVERLOADS, pos,
3019                             Warnings.PotentiallyAmbiguousOverload(msym1, msym1.location(),
3020                                                                   msym2, msym2.location()));
3021                 return;
3022             }
3023         }
3024     }
3025 
3026     void checkAccessFromSerializableElement(final JCTree tree, boolean isLambda) {
3027         if (warnOnAnyAccessToMembers ||
3028             (lint.isEnabled(LintCategory.SERIAL) &&
3029             !lint.isSuppressed(LintCategory.SERIAL) &&
3030             isLambda)) {
3031             Symbol sym = TreeInfo.symbol(tree);
3032             if (!sym.kind.matches(KindSelector.VAL_MTH)) {
3033                 return;
3034             }
3035 
3036             if (sym.kind == VAR) {
3037                 if ((sym.flags() & PARAMETER) != 0 ||
3038                     sym.isDirectlyOrIndirectlyLocal() ||
3039                     sym.name == names._this ||
3040                     sym.name == names._super) {
3041                     return;
3042                 }
3043             }
3044 
3045             if (!types.isSubtype(sym.owner.type, syms.serializableType) &&
3046                 isEffectivelyNonPublic(sym)) {
3047                 if (isLambda) {
3048                     if (belongsToRestrictedPackage(sym)) {
3049                         log.warning(LintCategory.SERIAL, tree.pos(),
3050                                     Warnings.AccessToMemberFromSerializableLambda(sym));
3051                     }
3052                 } else {
3053                     log.warning(tree.pos(),
3054                                 Warnings.AccessToMemberFromSerializableElement(sym));
3055                 }
3056             }
3057         }
3058     }
3059 
3060     private boolean isEffectivelyNonPublic(Symbol sym) {
3061         if (sym.packge() == syms.rootPackage) {
3062             return false;
3063         }
3064 
3065         while (sym.kind != PCK) {
3066             if ((sym.flags() & PUBLIC) == 0) {
3067                 return true;
3068             }
3069             sym = sym.owner;
3070         }
3071         return false;
3072     }
3073 
3074     private boolean belongsToRestrictedPackage(Symbol sym) {
3075         String fullName = sym.packge().fullname.toString();
3076         return fullName.startsWith("java.") ||
3077                 fullName.startsWith("javax.") ||
3078                 fullName.startsWith("sun.") ||
3079                 fullName.contains(".internal.");
3080     }
3081 
3082     /** Check that class c does not implement directly or indirectly
3083      *  the same parameterized interface with two different argument lists.
3084      *  @param pos          Position to be used for error reporting.
3085      *  @param type         The type whose interfaces are checked.
3086      */
3087     void checkClassBounds(DiagnosticPosition pos, Type type) {
3088         checkClassBounds(pos, new HashMap<TypeSymbol,Type>(), type);
3089     }
3090 //where
3091         /** Enter all interfaces of type `type' into the hash table `seensofar'
3092          *  with their class symbol as key and their type as value. Make
3093          *  sure no class is entered with two different types.
3094          */
3095         void checkClassBounds(DiagnosticPosition pos,
3096                               Map<TypeSymbol,Type> seensofar,
3097                               Type type) {
3098             if (type.isErroneous()) return;
3099             for (List<Type> l = types.interfaces(type); l.nonEmpty(); l = l.tail) {
3100                 Type it = l.head;
3101                 if (type.hasTag(CLASS) && !it.hasTag(CLASS)) continue; // JLS 8.1.5
3102 
3103                 Type oldit = seensofar.put(it.tsym, it);
3104                 if (oldit != null) {
3105                     List<Type> oldparams = oldit.allparams();
3106                     List<Type> newparams = it.allparams();
3107                     if (!types.containsTypeEquivalent(oldparams, newparams))
3108                         log.error(pos,
3109                                   Errors.CantInheritDiffArg(it.tsym,
3110                                                             Type.toString(oldparams),
3111                                                             Type.toString(newparams)));
3112                 }
3113                 checkClassBounds(pos, seensofar, it);
3114             }
3115             Type st = types.supertype(type);
3116             if (type.hasTag(CLASS) && !st.hasTag(CLASS)) return; // JLS 8.1.4
3117             if (st != Type.noType) checkClassBounds(pos, seensofar, st);
3118         }
3119 
3120     /** Enter interface into into set.
3121      *  If it existed already, issue a "repeated interface" error.
3122      */
3123     void checkNotRepeated(DiagnosticPosition pos, Type it, Set<Type> its) {
3124         if (its.contains(it))
3125             log.error(pos, Errors.RepeatedInterface);
3126         else {
3127             its.add(it);
3128         }
3129     }
3130 
3131 /* *************************************************************************
3132  * Check annotations
3133  **************************************************************************/
3134 
3135     /**
3136      * Recursively validate annotations values
3137      */
3138     void validateAnnotationTree(JCTree tree) {
3139         class AnnotationValidator extends TreeScanner {
3140             @Override
3141             public void visitAnnotation(JCAnnotation tree) {
3142                 if (!tree.type.isErroneous() && tree.type.tsym.isAnnotationType()) {
3143                     super.visitAnnotation(tree);
3144                     validateAnnotation(tree);
3145                 }
3146             }
3147         }
3148         tree.accept(new AnnotationValidator());
3149     }
3150 
3151     /**
3152      *  {@literal
3153      *  Annotation types are restricted to primitives, String, an
3154      *  enum, an annotation, Class, Class<?>, Class<? extends
3155      *  Anything>, arrays of the preceding.
3156      *  }
3157      */
3158     void validateAnnotationType(JCTree restype) {
3159         // restype may be null if an error occurred, so don't bother validating it
3160         if (restype != null) {
3161             validateAnnotationType(restype.pos(), restype.type);
3162         }
3163     }
3164 
3165     void validateAnnotationType(DiagnosticPosition pos, Type type) {
3166         if (type.isPrimitive()) return;
3167         if (types.isSameType(type, syms.stringType)) return;
3168         if ((type.tsym.flags() & Flags.ENUM) != 0) return;
3169         if ((type.tsym.flags() & Flags.ANNOTATION) != 0) return;
3170         if (types.cvarLowerBound(type).tsym == syms.classType.tsym) return;
3171         if (types.isArray(type) && !types.isArray(types.elemtype(type))) {
3172             validateAnnotationType(pos, types.elemtype(type));
3173             return;
3174         }
3175         log.error(pos, Errors.InvalidAnnotationMemberType);
3176     }
3177 
3178     /**
3179      * "It is also a compile-time error if any method declared in an
3180      * annotation type has a signature that is override-equivalent to
3181      * that of any public or protected method declared in class Object
3182      * or in the interface annotation.Annotation."
3183      *
3184      * @jls 9.6 Annotation Types
3185      */
3186     void validateAnnotationMethod(DiagnosticPosition pos, MethodSymbol m) {
3187         for (Type sup = syms.annotationType; sup.hasTag(CLASS); sup = types.supertype(sup)) {
3188             Scope s = sup.tsym.members();
3189             for (Symbol sym : s.getSymbolsByName(m.name)) {
3190                 if (sym.kind == MTH &&
3191                     (sym.flags() & (PUBLIC | PROTECTED)) != 0 &&
3192                     types.overrideEquivalent(m.type, sym.type))
3193                     log.error(pos, Errors.IntfAnnotationMemberClash(sym, sup));
3194             }
3195         }
3196     }
3197 
3198     /** Check the annotations of a symbol.
3199      */
3200     public void validateAnnotations(List<JCAnnotation> annotations, JCTree declarationTree, Symbol s) {
3201         for (JCAnnotation a : annotations)
3202             validateAnnotation(a, declarationTree, s);
3203     }
3204 
3205     /** Check the type annotations.
3206      */
3207     public void validateTypeAnnotations(List<JCAnnotation> annotations, boolean isTypeParameter) {
3208         for (JCAnnotation a : annotations)
3209             validateTypeAnnotation(a, isTypeParameter);
3210     }
3211 
3212     /** Check an annotation of a symbol.
3213      */
3214     private void validateAnnotation(JCAnnotation a, JCTree declarationTree, Symbol s) {
3215         validateAnnotationTree(a);
3216         boolean isRecordMember = ((s.flags_field & RECORD) != 0 || s.enclClass() != null && s.enclClass().isRecord());
3217 
3218         boolean isRecordField = (s.flags_field & RECORD) != 0 &&
3219                 declarationTree.hasTag(VARDEF) &&
3220                 s.owner.kind == TYP;
3221 
3222         if (isRecordField) {
3223             // first we need to check if the annotation is applicable to records
3224             Name[] targets = getTargetNames(a);
3225             boolean appliesToRecords = false;
3226             for (Name target : targets) {
3227                 appliesToRecords =
3228                                 target == names.FIELD ||
3229                                 target == names.PARAMETER ||
3230                                 target == names.METHOD ||
3231                                 target == names.TYPE_USE ||
3232                                 target == names.RECORD_COMPONENT;
3233                 if (appliesToRecords) {
3234                     break;
3235                 }
3236             }
3237             if (!appliesToRecords) {
3238                 log.error(a.pos(), Errors.AnnotationTypeNotApplicable);
3239             } else {
3240                 /* lets now find the annotations in the field that are targeted to record components and append them to
3241                  * the corresponding record component
3242                  */
3243                 ClassSymbol recordClass = (ClassSymbol) s.owner;
3244                 RecordComponent rc = recordClass.getRecordComponent((VarSymbol)s);
3245                 SymbolMetadata metadata = rc.getMetadata();
3246                 if (metadata == null || metadata.isEmpty()) {
3247                     /* if not is empty then we have already been here, which is the case if multiple annotations are applied
3248                      * to the record component declaration
3249                      */
3250                     rc.appendAttributes(s.getRawAttributes().stream().filter(anno ->
3251                             Arrays.stream(getTargetNames(anno.type.tsym)).anyMatch(name -> name == names.RECORD_COMPONENT)
3252                     ).collect(List.collector()));
3253                     rc.setTypeAttributes(s.getRawTypeAttributes());
3254                     // to get all the type annotations applied to the type
3255                     rc.type = s.type;
3256                 }
3257             }
3258         }
3259 
3260         /* the section below is tricky. Annotations applied to record components are propagated to the corresponding
3261          * record member so if an annotation has target: FIELD, it is propagated to the corresponding FIELD, if it has
3262          * target METHOD, it is propagated to the accessor and so on. But at the moment when method members are generated
3263          * there is no enough information to propagate only the right annotations. So all the annotations are propagated
3264          * to all the possible locations.
3265          *
3266          * At this point we need to remove all the annotations that are not in place before going on with the annotation
3267          * party. On top of the above there is the issue that there is no AST representing record components, just symbols
3268          * so the corresponding field has been holding all the annotations and it's metadata has been modified as if it
3269          * was both a field and a record component.
3270          *
3271          * So there are two places where we need to trim annotations from: the metadata of the symbol and / or the modifiers
3272          * in the AST. Whatever is in the metadata will be written to the class file, whatever is in the modifiers could
3273          * be see by annotation processors.
3274          *
3275          * The metadata contains both type annotations and declaration annotations. At this point of the game we don't
3276          * need to care about type annotations, they are all in the right place. But we could need to remove declaration
3277          * annotations. So for declaration annotations if they are not applicable to the record member, excluding type
3278          * annotations which are already correct, then we will remove it. For the AST modifiers if the annotation is not
3279          * applicable either as type annotation and or declaration annotation, only in that case it will be removed.
3280          *
3281          * So it could be that annotation is removed as a declaration annotation but it is kept in the AST modifier for
3282          * further inspection by annotation processors.
3283          *
3284          * For example:
3285          *
3286          *     import java.lang.annotation.*;
3287          *
3288          *     @Target({ElementType.TYPE_USE, ElementType.RECORD_COMPONENT})
3289          *     @Retention(RetentionPolicy.RUNTIME)
3290          *     @interface Anno { }
3291          *
3292          *     record R(@Anno String s) {}
3293          *
3294          * at this point we will have for the case of the generated field:
3295          *   - @Anno in the modifier
3296          *   - @Anno as a type annotation
3297          *   - @Anno as a declaration annotation
3298          *
3299          * the last one should be removed because the annotation has not FIELD as target but it was applied as a
3300          * declaration annotation because the field was being treated both as a field and as a record component
3301          * as we have already copied the annotations to the record component, now the field doesn't need to hold
3302          * annotations that are not intended for it anymore. Still @Anno has to be kept in the AST's modifiers as it
3303          * is applicable as a type annotation to the type of the field.
3304          */
3305 
3306         if (a.type.tsym.isAnnotationType()) {
3307             Optional<Set<Name>> applicableTargetsOp = getApplicableTargets(a, s);
3308             if (!applicableTargetsOp.isEmpty()) {
3309                 Set<Name> applicableTargets = applicableTargetsOp.get();
3310                 boolean notApplicableOrIsTypeUseOnly = applicableTargets.isEmpty() ||
3311                         applicableTargets.size() == 1 && applicableTargets.contains(names.TYPE_USE);
3312                 boolean isCompGeneratedRecordElement = isRecordMember && (s.flags_field & Flags.GENERATED_MEMBER) != 0;
3313                 boolean isCompRecordElementWithNonApplicableDeclAnno = isCompGeneratedRecordElement && notApplicableOrIsTypeUseOnly;
3314 
3315                 if (applicableTargets.isEmpty() || isCompRecordElementWithNonApplicableDeclAnno) {
3316                     if (isCompRecordElementWithNonApplicableDeclAnno) {
3317                             /* so we have found an annotation that is not applicable to a record member that was generated by the
3318                              * compiler. This was intentionally done at TypeEnter, now is the moment strip away the annotations
3319                              * that are not applicable to the given record member
3320                              */
3321                         JCModifiers modifiers = TreeInfo.getModifiers(declarationTree);
3322                             /* lets first remove the annotation from the modifier if it is not applicable, we have to check again as
3323                              * it could be a type annotation
3324                              */
3325                         if (modifiers != null && applicableTargets.isEmpty()) {
3326                             ListBuffer<JCAnnotation> newAnnotations = new ListBuffer<>();
3327                             for (JCAnnotation anno : modifiers.annotations) {
3328                                 if (anno != a) {
3329                                     newAnnotations.add(anno);
3330                                 }
3331                             }
3332                             modifiers.annotations = newAnnotations.toList();
3333                         }
3334                         // now lets remove it from the symbol
3335                         s.getMetadata().removeDeclarationMetadata(a.attribute);
3336                     } else {
3337                         log.error(a.pos(), Errors.AnnotationTypeNotApplicable);
3338                     }
3339                 }
3340                 /* if we are seeing the @SafeVarargs annotation applied to a compiler generated accessor,
3341                  * then this is an error as we know that no compiler generated accessor will be a varargs
3342                  * method, better to fail asap
3343                  */
3344                 if (isCompGeneratedRecordElement && !isRecordField && a.type.tsym == syms.trustMeType.tsym && declarationTree.hasTag(METHODDEF)) {
3345                     log.error(a.pos(), Errors.VarargsInvalidTrustmeAnno(syms.trustMeType.tsym, Fragments.VarargsTrustmeOnNonVarargsAccessor(s)));
3346                 }
3347             }
3348         }
3349 
3350         if (a.annotationType.type.tsym == syms.functionalInterfaceType.tsym) {
3351             if (s.kind != TYP) {
3352                 log.error(a.pos(), Errors.BadFunctionalIntfAnno);
3353             } else if (!s.isInterface() || (s.flags() & ANNOTATION) != 0) {
3354                 log.error(a.pos(), Errors.BadFunctionalIntfAnno1(Fragments.NotAFunctionalIntf(s)));
3355             }
3356         }
3357     }
3358 
3359     public void validateTypeAnnotation(JCAnnotation a, boolean isTypeParameter) {
3360         Assert.checkNonNull(a.type);
3361         validateAnnotationTree(a);
3362 
3363         if (a.hasTag(TYPE_ANNOTATION) &&
3364                 !a.annotationType.type.isErroneous() &&
3365                 !isTypeAnnotation(a, isTypeParameter)) {
3366             log.error(a.pos(), Errors.AnnotationTypeNotApplicableToType(a.type));
3367         }
3368     }
3369 
3370     /**
3371      * Validate the proposed container 'repeatable' on the
3372      * annotation type symbol 's'. Report errors at position
3373      * 'pos'.
3374      *
3375      * @param s The (annotation)type declaration annotated with a @Repeatable
3376      * @param repeatable the @Repeatable on 's'
3377      * @param pos where to report errors
3378      */
3379     public void validateRepeatable(TypeSymbol s, Attribute.Compound repeatable, DiagnosticPosition pos) {
3380         Assert.check(types.isSameType(repeatable.type, syms.repeatableType));
3381 
3382         Type t = null;
3383         List<Pair<MethodSymbol,Attribute>> l = repeatable.values;
3384         if (!l.isEmpty()) {
3385             Assert.check(l.head.fst.name == names.value);
3386             if (l.head.snd instanceof Attribute.Class) {
3387                 t = ((Attribute.Class)l.head.snd).getValue();
3388             }
3389         }
3390 
3391         if (t == null) {
3392             // errors should already have been reported during Annotate
3393             return;
3394         }
3395 
3396         validateValue(t.tsym, s, pos);
3397         validateRetention(t.tsym, s, pos);
3398         validateDocumented(t.tsym, s, pos);
3399         validateInherited(t.tsym, s, pos);
3400         validateTarget(t.tsym, s, pos);
3401         validateDefault(t.tsym, pos);
3402     }
3403 
3404     private void validateValue(TypeSymbol container, TypeSymbol contained, DiagnosticPosition pos) {
3405         Symbol sym = container.members().findFirst(names.value);
3406         if (sym != null && sym.kind == MTH) {
3407             MethodSymbol m = (MethodSymbol) sym;
3408             Type ret = m.getReturnType();
3409             if (!(ret.hasTag(ARRAY) && types.isSameType(((ArrayType)ret).elemtype, contained.type))) {
3410                 log.error(pos,
3411                           Errors.InvalidRepeatableAnnotationValueReturn(container,
3412                                                                         ret,
3413                                                                         types.makeArrayType(contained.type)));
3414             }
3415         } else {
3416             log.error(pos, Errors.InvalidRepeatableAnnotationNoValue(container));
3417         }
3418     }
3419 
3420     private void validateRetention(TypeSymbol container, TypeSymbol contained, DiagnosticPosition pos) {
3421         Attribute.RetentionPolicy containerRetention = types.getRetention(container);
3422         Attribute.RetentionPolicy containedRetention = types.getRetention(contained);
3423 
3424         boolean error = false;
3425         switch (containedRetention) {
3426         case RUNTIME:
3427             if (containerRetention != Attribute.RetentionPolicy.RUNTIME) {
3428                 error = true;
3429             }
3430             break;
3431         case CLASS:
3432             if (containerRetention == Attribute.RetentionPolicy.SOURCE)  {
3433                 error = true;
3434             }
3435         }
3436         if (error ) {
3437             log.error(pos,
3438                       Errors.InvalidRepeatableAnnotationRetention(container,
3439                                                                   containerRetention.name(),
3440                                                                   contained,
3441                                                                   containedRetention.name()));
3442         }
3443     }
3444 
3445     private void validateDocumented(Symbol container, Symbol contained, DiagnosticPosition pos) {
3446         if (contained.attribute(syms.documentedType.tsym) != null) {
3447             if (container.attribute(syms.documentedType.tsym) == null) {
3448                 log.error(pos, Errors.InvalidRepeatableAnnotationNotDocumented(container, contained));
3449             }
3450         }
3451     }
3452 
3453     private void validateInherited(Symbol container, Symbol contained, DiagnosticPosition pos) {
3454         if (contained.attribute(syms.inheritedType.tsym) != null) {
3455             if (container.attribute(syms.inheritedType.tsym) == null) {
3456                 log.error(pos, Errors.InvalidRepeatableAnnotationNotInherited(container, contained));
3457             }
3458         }
3459     }
3460 
3461     private void validateTarget(TypeSymbol container, TypeSymbol contained, DiagnosticPosition pos) {
3462         // The set of targets the container is applicable to must be a subset
3463         // (with respect to annotation target semantics) of the set of targets
3464         // the contained is applicable to. The target sets may be implicit or
3465         // explicit.
3466 
3467         Set<Name> containerTargets;
3468         Attribute.Array containerTarget = getAttributeTargetAttribute(container);
3469         if (containerTarget == null) {
3470             containerTargets = getDefaultTargetSet();
3471         } else {
3472             containerTargets = new HashSet<>();
3473             for (Attribute app : containerTarget.values) {
3474                 if (!(app instanceof Attribute.Enum attributeEnum)) {
3475                     continue; // recovery
3476                 }
3477                 containerTargets.add(attributeEnum.value.name);
3478             }
3479         }
3480 
3481         Set<Name> containedTargets;
3482         Attribute.Array containedTarget = getAttributeTargetAttribute(contained);
3483         if (containedTarget == null) {
3484             containedTargets = getDefaultTargetSet();
3485         } else {
3486             containedTargets = new HashSet<>();
3487             for (Attribute app : containedTarget.values) {
3488                 if (!(app instanceof Attribute.Enum attributeEnum)) {
3489                     continue; // recovery
3490                 }
3491                 containedTargets.add(attributeEnum.value.name);
3492             }
3493         }
3494 
3495         if (!isTargetSubsetOf(containerTargets, containedTargets)) {
3496             log.error(pos, Errors.InvalidRepeatableAnnotationIncompatibleTarget(container, contained));
3497         }
3498     }
3499 
3500     /* get a set of names for the default target */
3501     private Set<Name> getDefaultTargetSet() {
3502         if (defaultTargets == null) {
3503             defaultTargets = Set.of(defaultTargetMetaInfo());
3504         }
3505 
3506         return defaultTargets;
3507     }
3508     private Set<Name> defaultTargets;
3509 
3510 
3511     /** Checks that s is a subset of t, with respect to ElementType
3512      * semantics, specifically {ANNOTATION_TYPE} is a subset of {TYPE},
3513      * and {TYPE_USE} covers the set {ANNOTATION_TYPE, TYPE, TYPE_USE,
3514      * TYPE_PARAMETER}.
3515      */
3516     private boolean isTargetSubsetOf(Set<Name> s, Set<Name> t) {
3517         // Check that all elements in s are present in t
3518         for (Name n2 : s) {
3519             boolean currentElementOk = false;
3520             for (Name n1 : t) {
3521                 if (n1 == n2) {
3522                     currentElementOk = true;
3523                     break;
3524                 } else if (n1 == names.TYPE && n2 == names.ANNOTATION_TYPE) {
3525                     currentElementOk = true;
3526                     break;
3527                 } else if (n1 == names.TYPE_USE &&
3528                         (n2 == names.TYPE ||
3529                          n2 == names.ANNOTATION_TYPE ||
3530                          n2 == names.TYPE_PARAMETER)) {
3531                     currentElementOk = true;
3532                     break;
3533                 }
3534             }
3535             if (!currentElementOk)
3536                 return false;
3537         }
3538         return true;
3539     }
3540 
3541     private void validateDefault(Symbol container, DiagnosticPosition pos) {
3542         // validate that all other elements of containing type has defaults
3543         Scope scope = container.members();
3544         for(Symbol elm : scope.getSymbols()) {
3545             if (elm.name != names.value &&
3546                 elm.kind == MTH &&
3547                 ((MethodSymbol)elm).defaultValue == null) {
3548                 log.error(pos,
3549                           Errors.InvalidRepeatableAnnotationElemNondefault(container, elm));
3550             }
3551         }
3552     }
3553 
3554     /** Is s a method symbol that overrides a method in a superclass? */
3555     boolean isOverrider(Symbol s) {
3556         if (s.kind != MTH || s.isStatic())
3557             return false;
3558         MethodSymbol m = (MethodSymbol)s;
3559         TypeSymbol owner = (TypeSymbol)m.owner;
3560         for (Type sup : types.closure(owner.type)) {
3561             if (sup == owner.type)
3562                 continue; // skip "this"
3563             Scope scope = sup.tsym.members();
3564             for (Symbol sym : scope.getSymbolsByName(m.name)) {
3565                 if (!sym.isStatic() && m.overrides(sym, owner, types, true))
3566                     return true;
3567             }
3568         }
3569         return false;
3570     }
3571 
3572     /** Is the annotation applicable to types? */
3573     protected boolean isTypeAnnotation(JCAnnotation a, boolean isTypeParameter) {
3574         List<Attribute> targets = typeAnnotations.annotationTargets(a.annotationType.type.tsym);
3575         return (targets == null) ?
3576                 false :
3577                 targets.stream()
3578                         .anyMatch(attr -> isTypeAnnotation(attr, isTypeParameter));
3579     }
3580     //where
3581         boolean isTypeAnnotation(Attribute a, boolean isTypeParameter) {
3582             Attribute.Enum e = (Attribute.Enum)a;
3583             return (e.value.name == names.TYPE_USE ||
3584                     (isTypeParameter && e.value.name == names.TYPE_PARAMETER));
3585         }
3586 
3587     /** Is the annotation applicable to the symbol? */
3588     Name[] getTargetNames(JCAnnotation a) {
3589         return getTargetNames(a.annotationType.type.tsym);
3590     }
3591 
3592     public Name[] getTargetNames(TypeSymbol annoSym) {
3593         Attribute.Array arr = getAttributeTargetAttribute(annoSym);
3594         Name[] targets;
3595         if (arr == null) {
3596             targets = defaultTargetMetaInfo();
3597         } else {
3598             // TODO: can we optimize this?
3599             targets = new Name[arr.values.length];
3600             for (int i=0; i<arr.values.length; ++i) {
3601                 Attribute app = arr.values[i];
3602                 if (!(app instanceof Attribute.Enum attributeEnum)) {
3603                     return new Name[0];
3604                 }
3605                 targets[i] = attributeEnum.value.name;
3606             }
3607         }
3608         return targets;
3609     }
3610 
3611     boolean annotationApplicable(JCAnnotation a, Symbol s) {
3612         Optional<Set<Name>> targets = getApplicableTargets(a, s);
3613         /* the optional could be emtpy if the annotation is unknown in that case
3614          * we return that it is applicable and if it is erroneous that should imply
3615          * an error at the declaration site
3616          */
3617         return targets.isEmpty() || targets.isPresent() && !targets.get().isEmpty();
3618     }
3619 
3620     Optional<Set<Name>> getApplicableTargets(JCAnnotation a, Symbol s) {
3621         Attribute.Array arr = getAttributeTargetAttribute(a.annotationType.type.tsym);
3622         Name[] targets;
3623         Set<Name> applicableTargets = new HashSet<>();
3624 
3625         if (arr == null) {
3626             targets = defaultTargetMetaInfo();
3627         } else {
3628             // TODO: can we optimize this?
3629             targets = new Name[arr.values.length];
3630             for (int i=0; i<arr.values.length; ++i) {
3631                 Attribute app = arr.values[i];
3632                 if (!(app instanceof Attribute.Enum attributeEnum)) {
3633                     // recovery
3634                     return Optional.empty();
3635                 }
3636                 targets[i] = attributeEnum.value.name;
3637             }
3638         }
3639         for (Name target : targets) {
3640             if (target == names.TYPE) {
3641                 if (s.kind == TYP)
3642                     applicableTargets.add(names.TYPE);
3643             } else if (target == names.FIELD) {
3644                 if (s.kind == VAR && s.owner.kind != MTH)
3645                     applicableTargets.add(names.FIELD);
3646             } else if (target == names.RECORD_COMPONENT) {
3647                 if (s.getKind() == ElementKind.RECORD_COMPONENT) {
3648                     applicableTargets.add(names.RECORD_COMPONENT);
3649                 }
3650             } else if (target == names.METHOD) {
3651                 if (s.kind == MTH && !s.isConstructor())
3652                     applicableTargets.add(names.METHOD);
3653             } else if (target == names.PARAMETER) {
3654                 if (s.kind == VAR &&
3655                     (s.owner.kind == MTH && (s.flags() & PARAMETER) != 0)) {
3656                     applicableTargets.add(names.PARAMETER);
3657                 }
3658             } else if (target == names.CONSTRUCTOR) {
3659                 if (s.kind == MTH && s.isConstructor())
3660                     applicableTargets.add(names.CONSTRUCTOR);
3661             } else if (target == names.LOCAL_VARIABLE) {
3662                 if (s.kind == VAR && s.owner.kind == MTH &&
3663                       (s.flags() & PARAMETER) == 0) {
3664                     applicableTargets.add(names.LOCAL_VARIABLE);
3665                 }
3666             } else if (target == names.ANNOTATION_TYPE) {
3667                 if (s.kind == TYP && (s.flags() & ANNOTATION) != 0) {
3668                     applicableTargets.add(names.ANNOTATION_TYPE);
3669                 }
3670             } else if (target == names.PACKAGE) {
3671                 if (s.kind == PCK)
3672                     applicableTargets.add(names.PACKAGE);
3673             } else if (target == names.TYPE_USE) {
3674                 if (s.kind == VAR && s.owner.kind == MTH && s.type.hasTag(NONE)) {
3675                     //cannot type annotate implicitly typed locals
3676                     continue;
3677                 } else if (s.kind == TYP || s.kind == VAR ||
3678                         (s.kind == MTH && !s.isConstructor() &&
3679                                 !s.type.getReturnType().hasTag(VOID)) ||
3680                         (s.kind == MTH && s.isConstructor())) {
3681                     applicableTargets.add(names.TYPE_USE);
3682                 }
3683             } else if (target == names.TYPE_PARAMETER) {
3684                 if (s.kind == TYP && s.type.hasTag(TYPEVAR))
3685                     applicableTargets.add(names.TYPE_PARAMETER);
3686             } else if (target == names.MODULE) {
3687                 if (s.kind == MDL)
3688                     applicableTargets.add(names.MODULE);
3689             } else
3690                 return Optional.empty(); // Unknown ElementType. This should be an error at declaration site,
3691                                          // assume applicable.
3692         }
3693         return Optional.of(applicableTargets);
3694     }
3695 
3696     Attribute.Array getAttributeTargetAttribute(TypeSymbol s) {
3697         Attribute.Compound atTarget = s.getAnnotationTypeMetadata().getTarget();
3698         if (atTarget == null) return null; // ok, is applicable
3699         Attribute atValue = atTarget.member(names.value);
3700         return (atValue instanceof Attribute.Array attributeArray) ? attributeArray : null;
3701     }
3702 
3703     private Name[] dfltTargetMeta;
3704     private Name[] defaultTargetMetaInfo() {
3705         if (dfltTargetMeta == null) {
3706             ArrayList<Name> defaultTargets = new ArrayList<>();
3707             defaultTargets.add(names.PACKAGE);
3708             defaultTargets.add(names.TYPE);
3709             defaultTargets.add(names.FIELD);
3710             defaultTargets.add(names.METHOD);
3711             defaultTargets.add(names.CONSTRUCTOR);
3712             defaultTargets.add(names.ANNOTATION_TYPE);
3713             defaultTargets.add(names.LOCAL_VARIABLE);
3714             defaultTargets.add(names.PARAMETER);
3715             if (allowRecords) {
3716               defaultTargets.add(names.RECORD_COMPONENT);
3717             }
3718             if (allowModules) {
3719               defaultTargets.add(names.MODULE);
3720             }
3721             dfltTargetMeta = defaultTargets.toArray(new Name[0]);
3722         }
3723         return dfltTargetMeta;
3724     }
3725 
3726     /** Check an annotation value.
3727      *
3728      * @param a The annotation tree to check
3729      * @return true if this annotation tree is valid, otherwise false
3730      */
3731     public boolean validateAnnotationDeferErrors(JCAnnotation a) {
3732         boolean res = false;
3733         final Log.DiagnosticHandler diagHandler = new Log.DiscardDiagnosticHandler(log);
3734         try {
3735             res = validateAnnotation(a);
3736         } finally {
3737             log.popDiagnosticHandler(diagHandler);
3738         }
3739         return res;
3740     }
3741 
3742     private boolean validateAnnotation(JCAnnotation a) {
3743         boolean isValid = true;
3744         AnnotationTypeMetadata metadata = a.annotationType.type.tsym.getAnnotationTypeMetadata();
3745 
3746         // collect an inventory of the annotation elements
3747         Set<MethodSymbol> elements = metadata.getAnnotationElements();
3748 
3749         // remove the ones that are assigned values
3750         for (JCTree arg : a.args) {
3751             if (!arg.hasTag(ASSIGN)) continue; // recovery
3752             JCAssign assign = (JCAssign)arg;
3753             Symbol m = TreeInfo.symbol(assign.lhs);
3754             if (m == null || m.type.isErroneous()) continue;
3755             if (!elements.remove(m)) {
3756                 isValid = false;
3757                 log.error(assign.lhs.pos(),
3758                           Errors.DuplicateAnnotationMemberValue(m.name, a.type));
3759             }
3760         }
3761 
3762         // all the remaining ones better have default values
3763         List<Name> missingDefaults = List.nil();
3764         Set<MethodSymbol> membersWithDefault = metadata.getAnnotationElementsWithDefault();
3765         for (MethodSymbol m : elements) {
3766             if (m.type.isErroneous())
3767                 continue;
3768 
3769             if (!membersWithDefault.contains(m))
3770                 missingDefaults = missingDefaults.append(m.name);
3771         }
3772         missingDefaults = missingDefaults.reverse();
3773         if (missingDefaults.nonEmpty()) {
3774             isValid = false;
3775             Error errorKey = (missingDefaults.size() > 1)
3776                     ? Errors.AnnotationMissingDefaultValue1(a.type, missingDefaults)
3777                     : Errors.AnnotationMissingDefaultValue(a.type, missingDefaults);
3778             log.error(a.pos(), errorKey);
3779         }
3780 
3781         return isValid && validateTargetAnnotationValue(a);
3782     }
3783 
3784     /* Validate the special java.lang.annotation.Target annotation */
3785     boolean validateTargetAnnotationValue(JCAnnotation a) {
3786         // special case: java.lang.annotation.Target must not have
3787         // repeated values in its value member
3788         if (a.annotationType.type.tsym != syms.annotationTargetType.tsym ||
3789                 a.args.tail == null)
3790             return true;
3791 
3792         boolean isValid = true;
3793         if (!a.args.head.hasTag(ASSIGN)) return false; // error recovery
3794         JCAssign assign = (JCAssign) a.args.head;
3795         Symbol m = TreeInfo.symbol(assign.lhs);
3796         if (m.name != names.value) return false;
3797         JCTree rhs = assign.rhs;
3798         if (!rhs.hasTag(NEWARRAY)) return false;
3799         JCNewArray na = (JCNewArray) rhs;
3800         Set<Symbol> targets = new HashSet<>();
3801         for (JCTree elem : na.elems) {
3802             if (!targets.add(TreeInfo.symbol(elem))) {
3803                 isValid = false;
3804                 log.error(elem.pos(), Errors.RepeatedAnnotationTarget);
3805             }
3806         }
3807         return isValid;
3808     }
3809 
3810     void checkDeprecatedAnnotation(DiagnosticPosition pos, Symbol s) {
3811         if (lint.isEnabled(LintCategory.DEP_ANN) && s.isDeprecatableViaAnnotation() &&
3812             (s.flags() & DEPRECATED) != 0 &&
3813             !syms.deprecatedType.isErroneous() &&
3814             s.attribute(syms.deprecatedType.tsym) == null) {
3815             log.warning(LintCategory.DEP_ANN,
3816                     pos, Warnings.MissingDeprecatedAnnotation);
3817         }
3818         // Note: @Deprecated has no effect on local variables, parameters and package decls.
3819         if (lint.isEnabled(LintCategory.DEPRECATION) && !s.isDeprecatableViaAnnotation()) {
3820             if (!syms.deprecatedType.isErroneous() && s.attribute(syms.deprecatedType.tsym) != null) {
3821                 log.warning(LintCategory.DEPRECATION, pos,
3822                             Warnings.DeprecatedAnnotationHasNoEffect(Kinds.kindName(s)));
3823             }
3824         }
3825     }
3826 
3827     void checkDeprecated(final DiagnosticPosition pos, final Symbol other, final Symbol s) {
3828         checkDeprecated(() -> pos, other, s);
3829     }
3830 
3831     void checkDeprecated(Supplier<DiagnosticPosition> pos, final Symbol other, final Symbol s) {
3832         if ( (s.isDeprecatedForRemoval()
3833                 || s.isDeprecated() && !other.isDeprecated())
3834                 && (s.outermostClass() != other.outermostClass() || s.outermostClass() == null)
3835                 && s.kind != Kind.PCK) {
3836             deferredLintHandler.report(() -> warnDeprecated(pos.get(), s));
3837         }
3838     }
3839 
3840     void checkSunAPI(final DiagnosticPosition pos, final Symbol s) {
3841         if ((s.flags() & PROPRIETARY) != 0) {
3842             deferredLintHandler.report(() -> {
3843                 log.mandatoryWarning(pos, Warnings.SunProprietary(s));
3844             });
3845         }
3846     }
3847 
3848     void checkProfile(final DiagnosticPosition pos, final Symbol s) {
3849         if (profile != Profile.DEFAULT && (s.flags() & NOT_IN_PROFILE) != 0) {
3850             log.error(pos, Errors.NotInProfile(s, profile));
3851         }
3852     }
3853 
3854     void checkPreview(DiagnosticPosition pos, Symbol other, Symbol s) {
3855         if ((s.flags() & PREVIEW_API) != 0 && s.packge().modle != other.packge().modle) {
3856             if ((s.flags() & PREVIEW_REFLECTIVE) == 0) {
3857                 if (!preview.isEnabled()) {
3858                     log.error(pos, Errors.IsPreview(s));
3859                 } else {
3860                     preview.markUsesPreview(pos);
3861                     deferredLintHandler.report(() -> warnPreviewAPI(pos, Warnings.IsPreview(s)));
3862                 }
3863             } else {
3864                     deferredLintHandler.report(() -> warnPreviewAPI(pos, Warnings.IsPreviewReflective(s)));
3865             }
3866         }
3867         if (preview.declaredUsingPreviewFeature(s)) {
3868             if (preview.isEnabled()) {
3869                 //for preview disabled do presumably so not need to do anything?
3870                 //If "s" is compiled from source, then there was an error for it already;
3871                 //if "s" is from classfile, there already was an error for the classfile.
3872                 preview.markUsesPreview(pos);
3873                 deferredLintHandler.report(() -> warnDeclaredUsingPreview(pos, s));
3874             }
3875         }
3876     }
3877 
3878 /* *************************************************************************
3879  * Check for recursive annotation elements.
3880  **************************************************************************/
3881 
3882     /** Check for cycles in the graph of annotation elements.
3883      */
3884     void checkNonCyclicElements(JCClassDecl tree) {
3885         if ((tree.sym.flags_field & ANNOTATION) == 0) return;
3886         Assert.check((tree.sym.flags_field & LOCKED) == 0);
3887         try {
3888             tree.sym.flags_field |= LOCKED;
3889             for (JCTree def : tree.defs) {
3890                 if (!def.hasTag(METHODDEF)) continue;
3891                 JCMethodDecl meth = (JCMethodDecl)def;
3892                 checkAnnotationResType(meth.pos(), meth.restype.type);
3893             }
3894         } finally {
3895             tree.sym.flags_field &= ~LOCKED;
3896             tree.sym.flags_field |= ACYCLIC_ANN;
3897         }
3898     }
3899 
3900     void checkNonCyclicElementsInternal(DiagnosticPosition pos, TypeSymbol tsym) {
3901         if ((tsym.flags_field & ACYCLIC_ANN) != 0)
3902             return;
3903         if ((tsym.flags_field & LOCKED) != 0) {
3904             log.error(pos, Errors.CyclicAnnotationElement(tsym));
3905             return;
3906         }
3907         try {
3908             tsym.flags_field |= LOCKED;
3909             for (Symbol s : tsym.members().getSymbols(NON_RECURSIVE)) {
3910                 if (s.kind != MTH)
3911                     continue;
3912                 checkAnnotationResType(pos, ((MethodSymbol)s).type.getReturnType());
3913             }
3914         } finally {
3915             tsym.flags_field &= ~LOCKED;
3916             tsym.flags_field |= ACYCLIC_ANN;
3917         }
3918     }
3919 
3920     void checkAnnotationResType(DiagnosticPosition pos, Type type) {
3921         switch (type.getTag()) {
3922         case CLASS:
3923             if ((type.tsym.flags() & ANNOTATION) != 0)
3924                 checkNonCyclicElementsInternal(pos, type.tsym);
3925             break;
3926         case ARRAY:
3927             checkAnnotationResType(pos, types.elemtype(type));
3928             break;
3929         default:
3930             break; // int etc
3931         }
3932     }
3933 
3934 /* *************************************************************************
3935  * Check for cycles in the constructor call graph.
3936  **************************************************************************/
3937 
3938     /** Check for cycles in the graph of constructors calling other
3939      *  constructors.
3940      */
3941     void checkCyclicConstructors(JCClassDecl tree) {
3942         Map<Symbol,Symbol> callMap = new HashMap<>();
3943 
3944         // enter each constructor this-call into the map
3945         for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
3946             JCMethodInvocation app = TreeInfo.firstConstructorCall(l.head);
3947             if (app == null) continue;
3948             JCMethodDecl meth = (JCMethodDecl) l.head;
3949             if (TreeInfo.name(app.meth) == names._this) {
3950                 callMap.put(meth.sym, TreeInfo.symbol(app.meth));
3951             } else {
3952                 meth.sym.flags_field |= ACYCLIC;
3953             }
3954         }
3955 
3956         // Check for cycles in the map
3957         Symbol[] ctors = new Symbol[0];
3958         ctors = callMap.keySet().toArray(ctors);
3959         for (Symbol caller : ctors) {
3960             checkCyclicConstructor(tree, caller, callMap);
3961         }
3962     }
3963 
3964     /** Look in the map to see if the given constructor is part of a
3965      *  call cycle.
3966      */
3967     private void checkCyclicConstructor(JCClassDecl tree, Symbol ctor,
3968                                         Map<Symbol,Symbol> callMap) {
3969         if (ctor != null && (ctor.flags_field & ACYCLIC) == 0) {
3970             if ((ctor.flags_field & LOCKED) != 0) {
3971                 log.error(TreeInfo.diagnosticPositionFor(ctor, tree),
3972                           Errors.RecursiveCtorInvocation);
3973             } else {
3974                 ctor.flags_field |= LOCKED;
3975                 checkCyclicConstructor(tree, callMap.remove(ctor), callMap);
3976                 ctor.flags_field &= ~LOCKED;
3977             }
3978             ctor.flags_field |= ACYCLIC;
3979         }
3980     }
3981 
3982 /* *************************************************************************
3983  * Miscellaneous
3984  **************************************************************************/
3985 
3986     /**
3987      *  Check for division by integer constant zero
3988      *  @param pos           Position for error reporting.
3989      *  @param operator      The operator for the expression
3990      *  @param operand       The right hand operand for the expression
3991      */
3992     void checkDivZero(final DiagnosticPosition pos, Symbol operator, Type operand) {
3993         if (operand.constValue() != null
3994             && operand.getTag().isSubRangeOf(LONG)
3995             && ((Number) (operand.constValue())).longValue() == 0) {
3996             int opc = ((OperatorSymbol)operator).opcode;
3997             if (opc == ByteCodes.idiv || opc == ByteCodes.imod
3998                 || opc == ByteCodes.ldiv || opc == ByteCodes.lmod) {
3999                 deferredLintHandler.report(() -> warnDivZero(pos));
4000             }
4001         }
4002     }
4003 
4004     /**
4005      * Check for empty statements after if
4006      */
4007     void checkEmptyIf(JCIf tree) {
4008         if (tree.thenpart.hasTag(SKIP) && tree.elsepart == null &&
4009                 lint.isEnabled(LintCategory.EMPTY))
4010             log.warning(LintCategory.EMPTY, tree.thenpart.pos(), Warnings.EmptyIf);
4011     }
4012 
4013     /** Check that symbol is unique in given scope.
4014      *  @param pos           Position for error reporting.
4015      *  @param sym           The symbol.
4016      *  @param s             The scope.
4017      */
4018     boolean checkUnique(DiagnosticPosition pos, Symbol sym, Scope s) {
4019         if (sym.type.isErroneous())
4020             return true;
4021         if (sym.owner.name == names.any) return false;
4022         for (Symbol byName : s.getSymbolsByName(sym.name, NON_RECURSIVE)) {
4023             if (sym != byName &&
4024                     (byName.flags() & CLASH) == 0 &&
4025                     sym.kind == byName.kind &&
4026                     sym.name != names.error &&
4027                     (sym.kind != MTH ||
4028                      types.hasSameArgs(sym.type, byName.type) ||
4029                      types.hasSameArgs(types.erasure(sym.type), types.erasure(byName.type)))) {
4030                 if ((sym.flags() & VARARGS) != (byName.flags() & VARARGS)) {
4031                     sym.flags_field |= CLASH;
4032                     varargsDuplicateError(pos, sym, byName);
4033                     return true;
4034                 } else if (sym.kind == MTH && !types.hasSameArgs(sym.type, byName.type, false)) {
4035                     duplicateErasureError(pos, sym, byName);
4036                     sym.flags_field |= CLASH;
4037                     return true;
4038                 } else if ((sym.flags() & MATCH_BINDING) != 0 &&
4039                            (byName.flags() & MATCH_BINDING) != 0 &&
4040                            (byName.flags() & MATCH_BINDING_TO_OUTER) == 0) {
4041                     if (!sym.type.isErroneous()) {
4042                         log.error(pos, Errors.MatchBindingExists);
4043                         sym.flags_field |= CLASH;
4044                     }
4045                     return false;
4046                 } else {
4047                     duplicateError(pos, byName);
4048                     return false;
4049                 }
4050             }
4051         }
4052         return true;
4053     }
4054 
4055     /** Report duplicate declaration error.
4056      */
4057     void duplicateErasureError(DiagnosticPosition pos, Symbol sym1, Symbol sym2) {
4058         if (!sym1.type.isErroneous() && !sym2.type.isErroneous()) {
4059             log.error(pos, Errors.NameClashSameErasure(sym1, sym2));
4060         }
4061     }
4062 
4063     /**Check that types imported through the ordinary imports don't clash with types imported
4064      * by other (static or ordinary) imports. Note that two static imports may import two clashing
4065      * types without an error on the imports.
4066      * @param toplevel       The toplevel tree for which the test should be performed.
4067      */
4068     void checkImportsUnique(JCCompilationUnit toplevel) {
4069         WriteableScope ordinallyImportedSoFar = WriteableScope.create(toplevel.packge);
4070         WriteableScope staticallyImportedSoFar = WriteableScope.create(toplevel.packge);
4071         WriteableScope topLevelScope = toplevel.toplevelScope;
4072 
4073         for (JCTree def : toplevel.defs) {
4074             if (!def.hasTag(IMPORT))
4075                 continue;
4076 
4077             JCImport imp = (JCImport) def;
4078 
4079             if (imp.importScope == null)
4080                 continue;
4081 
4082             for (Symbol sym : imp.importScope.getSymbols(sym -> sym.kind == TYP)) {
4083                 if (imp.isStatic()) {
4084                     checkUniqueImport(imp.pos(), ordinallyImportedSoFar, staticallyImportedSoFar, topLevelScope, sym, true);
4085                     staticallyImportedSoFar.enter(sym);
4086                 } else {
4087                     checkUniqueImport(imp.pos(), ordinallyImportedSoFar, staticallyImportedSoFar, topLevelScope, sym, false);
4088                     ordinallyImportedSoFar.enter(sym);
4089                 }
4090             }
4091 
4092             imp.importScope = null;
4093         }
4094     }
4095 
4096     /** Check that single-type import is not already imported or top-level defined,
4097      *  but make an exception for two single-type imports which denote the same type.
4098      *  @param pos                     Position for error reporting.
4099      *  @param ordinallyImportedSoFar  A Scope containing types imported so far through
4100      *                                 ordinary imports.
4101      *  @param staticallyImportedSoFar A Scope containing types imported so far through
4102      *                                 static imports.
4103      *  @param topLevelScope           The current file's top-level Scope
4104      *  @param sym                     The symbol.
4105      *  @param staticImport            Whether or not this was a static import
4106      */
4107     private boolean checkUniqueImport(DiagnosticPosition pos, Scope ordinallyImportedSoFar,
4108                                       Scope staticallyImportedSoFar, Scope topLevelScope,
4109                                       Symbol sym, boolean staticImport) {
4110         Predicate<Symbol> duplicates = candidate -> candidate != sym && !candidate.type.isErroneous();
4111         Symbol ordinaryClashing = ordinallyImportedSoFar.findFirst(sym.name, duplicates);
4112         Symbol staticClashing = null;
4113         if (ordinaryClashing == null && !staticImport) {
4114             staticClashing = staticallyImportedSoFar.findFirst(sym.name, duplicates);
4115         }
4116         if (ordinaryClashing != null || staticClashing != null) {
4117             if (ordinaryClashing != null)
4118                 log.error(pos, Errors.AlreadyDefinedSingleImport(ordinaryClashing));
4119             else
4120                 log.error(pos, Errors.AlreadyDefinedStaticSingleImport(staticClashing));
4121             return false;
4122         }
4123         Symbol clashing = topLevelScope.findFirst(sym.name, duplicates);
4124         if (clashing != null) {
4125             log.error(pos, Errors.AlreadyDefinedThisUnit(clashing));
4126             return false;
4127         }
4128         return true;
4129     }
4130 
4131     /** Check that a qualified name is in canonical form (for import decls).
4132      */
4133     public void checkCanonical(JCTree tree) {
4134         if (!isCanonical(tree))
4135             log.error(tree.pos(),
4136                       Errors.ImportRequiresCanonical(TreeInfo.symbol(tree)));
4137     }
4138         // where
4139         private boolean isCanonical(JCTree tree) {
4140             while (tree.hasTag(SELECT)) {
4141                 JCFieldAccess s = (JCFieldAccess) tree;
4142                 if (s.sym.owner.getQualifiedName() != TreeInfo.symbol(s.selected).getQualifiedName())
4143                     return false;
4144                 tree = s.selected;
4145             }
4146             return true;
4147         }
4148 
4149     /** Check that an auxiliary class is not accessed from any other file than its own.
4150      */
4151     void checkForBadAuxiliaryClassAccess(DiagnosticPosition pos, Env<AttrContext> env, ClassSymbol c) {
4152         if (lint.isEnabled(Lint.LintCategory.AUXILIARYCLASS) &&
4153             (c.flags() & AUXILIARY) != 0 &&
4154             rs.isAccessible(env, c) &&
4155             !fileManager.isSameFile(c.sourcefile, env.toplevel.sourcefile))
4156         {
4157             log.warning(pos,
4158                         Warnings.AuxiliaryClassAccessedFromOutsideOfItsSourceFile(c, c.sourcefile));
4159         }
4160     }
4161 
4162     /**
4163      * Check for a default constructor in an exported package.
4164      */
4165     void checkDefaultConstructor(ClassSymbol c, DiagnosticPosition pos) {
4166         if (lint.isEnabled(LintCategory.MISSING_EXPLICIT_CTOR) &&
4167             ((c.flags() & (ENUM | RECORD)) == 0) &&
4168             !c.isAnonymous() &&
4169             ((c.flags() & (PUBLIC | PROTECTED)) != 0) &&
4170             Feature.MODULES.allowedInSource(source)) {
4171             NestingKind nestingKind = c.getNestingKind();
4172             switch (nestingKind) {
4173                 case ANONYMOUS,
4174                      LOCAL -> {return;}
4175                 case TOP_LEVEL -> {;} // No additional checks needed
4176                 case MEMBER -> {
4177                     // For nested member classes, all the enclosing
4178                     // classes must be public or protected.
4179                     Symbol owner = c.owner;
4180                     while (owner != null && owner.kind == TYP) {
4181                         if ((owner.flags() & (PUBLIC | PROTECTED)) == 0)
4182                             return;
4183                         owner = owner.owner;
4184                     }
4185                 }
4186             }
4187 
4188             // Only check classes in named packages exported by its module
4189             PackageSymbol pkg = c.packge();
4190             if (!pkg.isUnnamed()) {
4191                 ModuleSymbol modle = pkg.modle;
4192                 for (ExportsDirective exportDir : modle.exports) {
4193                     // Report warning only if the containing
4194                     // package is unconditionally exported
4195                     if (exportDir.packge.equals(pkg)) {
4196                         if (exportDir.modules == null || exportDir.modules.isEmpty()) {
4197                             // Warning may be suppressed by
4198                             // annotations; check again for being
4199                             // enabled in the deferred context.
4200                             deferredLintHandler.report(() -> {
4201                                 if (lint.isEnabled(LintCategory.MISSING_EXPLICIT_CTOR))
4202                                    log.warning(LintCategory.MISSING_EXPLICIT_CTOR,
4203                                                pos, Warnings.MissingExplicitCtor(c, pkg, modle));
4204                                                        });
4205                         } else {
4206                             return;
4207                         }
4208                     }
4209                 }
4210             }
4211         }
4212         return;
4213     }
4214 
4215     private class ConversionWarner extends Warner {
4216         final String uncheckedKey;
4217         final Type found;
4218         final Type expected;
4219         public ConversionWarner(DiagnosticPosition pos, String uncheckedKey, Type found, Type expected) {
4220             super(pos);
4221             this.uncheckedKey = uncheckedKey;
4222             this.found = found;
4223             this.expected = expected;
4224         }
4225 
4226         @Override
4227         public void warn(LintCategory lint) {
4228             boolean warned = this.warned;
4229             super.warn(lint);
4230             if (warned) return; // suppress redundant diagnostics
4231             switch (lint) {
4232                 case UNCHECKED:
4233                     Check.this.warnUnchecked(pos(), Warnings.ProbFoundReq(diags.fragment(uncheckedKey), found, expected));
4234                     break;
4235                 case VARARGS:
4236                     if (method != null &&
4237                             method.attribute(syms.trustMeType.tsym) != null &&
4238                             isTrustMeAllowedOnMethod(method) &&
4239                             !types.isReifiable(method.type.getParameterTypes().last())) {
4240                         Check.this.warnUnsafeVararg(pos(), Warnings.VarargsUnsafeUseVarargsParam(method.params.last()));
4241                     }
4242                     break;
4243                 default:
4244                     throw new AssertionError("Unexpected lint: " + lint);
4245             }
4246         }
4247     }
4248 
4249     public Warner castWarner(DiagnosticPosition pos, Type found, Type expected) {
4250         return new ConversionWarner(pos, "unchecked.cast.to.type", found, expected);
4251     }
4252 
4253     public Warner convertWarner(DiagnosticPosition pos, Type found, Type expected) {
4254         return new ConversionWarner(pos, "unchecked.assign", found, expected);
4255     }
4256 
4257     public void checkFunctionalInterface(JCClassDecl tree, ClassSymbol cs) {
4258         Compound functionalType = cs.attribute(syms.functionalInterfaceType.tsym);
4259 
4260         if (functionalType != null) {
4261             try {
4262                 types.findDescriptorSymbol((TypeSymbol)cs);
4263             } catch (Types.FunctionDescriptorLookupError ex) {
4264                 DiagnosticPosition pos = tree.pos();
4265                 for (JCAnnotation a : tree.getModifiers().annotations) {
4266                     if (a.annotationType.type.tsym == syms.functionalInterfaceType.tsym) {
4267                         pos = a.pos();
4268                         break;
4269                     }
4270                 }
4271                 log.error(pos, Errors.BadFunctionalIntfAnno1(ex.getDiagnostic()));
4272             }
4273         }
4274     }
4275 
4276     public void checkImportsResolvable(final JCCompilationUnit toplevel) {
4277         for (final JCImport imp : toplevel.getImports()) {
4278             if (!imp.staticImport || !imp.qualid.hasTag(SELECT))
4279                 continue;
4280             final JCFieldAccess select = (JCFieldAccess) imp.qualid;
4281             final Symbol origin;
4282             if (select.name == names.asterisk || (origin = TreeInfo.symbol(select.selected)) == null || origin.kind != TYP)
4283                 continue;
4284 
4285             TypeSymbol site = (TypeSymbol) TreeInfo.symbol(select.selected);
4286             if (!checkTypeContainsImportableElement(site, site, toplevel.packge, select.name, new HashSet<Symbol>())) {
4287                 log.error(imp.pos(),
4288                           Errors.CantResolveLocation(KindName.STATIC,
4289                                                      select.name,
4290                                                      null,
4291                                                      null,
4292                                                      Fragments.Location(kindName(site),
4293                                                                         site,
4294                                                                         null)));
4295             }
4296         }
4297     }
4298 
4299     // Check that packages imported are in scope (JLS 7.4.3, 6.3, 6.5.3.1, 6.5.3.2)
4300     public void checkImportedPackagesObservable(final JCCompilationUnit toplevel) {
4301         OUTER: for (JCImport imp : toplevel.getImports()) {
4302             if (!imp.staticImport && TreeInfo.name(imp.qualid) == names.asterisk) {
4303                 TypeSymbol tsym = ((JCFieldAccess)imp.qualid).selected.type.tsym;
4304                 if (tsym.kind == PCK && tsym.members().isEmpty() &&
4305                     !(Feature.IMPORT_ON_DEMAND_OBSERVABLE_PACKAGES.allowedInSource(source) && tsym.exists())) {
4306                     log.error(DiagnosticFlag.RESOLVE_ERROR, imp.pos, Errors.DoesntExist(tsym));
4307                 }
4308             }
4309         }
4310     }
4311 
4312     private boolean checkTypeContainsImportableElement(TypeSymbol tsym, TypeSymbol origin, PackageSymbol packge, Name name, Set<Symbol> processed) {
4313         if (tsym == null || !processed.add(tsym))
4314             return false;
4315 
4316             // also search through inherited names
4317         if (checkTypeContainsImportableElement(types.supertype(tsym.type).tsym, origin, packge, name, processed))
4318             return true;
4319 
4320         for (Type t : types.interfaces(tsym.type))
4321             if (checkTypeContainsImportableElement(t.tsym, origin, packge, name, processed))
4322                 return true;
4323 
4324         for (Symbol sym : tsym.members().getSymbolsByName(name)) {
4325             if (sym.isStatic() &&
4326                 importAccessible(sym, packge) &&
4327                 sym.isMemberOf(origin, types)) {
4328                 return true;
4329             }
4330         }
4331 
4332         return false;
4333     }
4334 
4335     // is the sym accessible everywhere in packge?
4336     public boolean importAccessible(Symbol sym, PackageSymbol packge) {
4337         try {
4338             int flags = (int)(sym.flags() & AccessFlags);
4339             switch (flags) {
4340             default:
4341             case PUBLIC:
4342                 return true;
4343             case PRIVATE:
4344                 return false;
4345             case 0:
4346             case PROTECTED:
4347                 return sym.packge() == packge;
4348             }
4349         } catch (ClassFinder.BadClassFile err) {
4350             throw err;
4351         } catch (CompletionFailure ex) {
4352             return false;
4353         }
4354     }
4355 
4356     public void checkLeaksNotAccessible(Env<AttrContext> env, JCClassDecl check) {
4357         JCCompilationUnit toplevel = env.toplevel;
4358 
4359         if (   toplevel.modle == syms.unnamedModule
4360             || toplevel.modle == syms.noModule
4361             || (check.sym.flags() & COMPOUND) != 0) {
4362             return ;
4363         }
4364 
4365         ExportsDirective currentExport = findExport(toplevel.packge);
4366 
4367         if (   currentExport == null //not exported
4368             || currentExport.modules != null) //don't check classes in qualified export
4369             return ;
4370 
4371         new TreeScanner() {
4372             Lint lint = env.info.lint;
4373             boolean inSuperType;
4374 
4375             @Override
4376             public void visitBlock(JCBlock tree) {
4377             }
4378             @Override
4379             public void visitMethodDef(JCMethodDecl tree) {
4380                 if (!isAPISymbol(tree.sym))
4381                     return;
4382                 Lint prevLint = lint;
4383                 try {
4384                     lint = lint.augment(tree.sym);
4385                     if (lint.isEnabled(LintCategory.EXPORTS)) {
4386                         super.visitMethodDef(tree);
4387                     }
4388                 } finally {
4389                     lint = prevLint;
4390                 }
4391             }
4392             @Override
4393             public void visitVarDef(JCVariableDecl tree) {
4394                 if (!isAPISymbol(tree.sym) && tree.sym.owner.kind != MTH)
4395                     return;
4396                 Lint prevLint = lint;
4397                 try {
4398                     lint = lint.augment(tree.sym);
4399                     if (lint.isEnabled(LintCategory.EXPORTS)) {
4400                         scan(tree.mods);
4401                         scan(tree.vartype);
4402                     }
4403                 } finally {
4404                     lint = prevLint;
4405                 }
4406             }
4407             @Override
4408             public void visitClassDef(JCClassDecl tree) {
4409                 if (tree != check)
4410                     return ;
4411 
4412                 if (!isAPISymbol(tree.sym))
4413                     return ;
4414 
4415                 Lint prevLint = lint;
4416                 try {
4417                     lint = lint.augment(tree.sym);
4418                     if (lint.isEnabled(LintCategory.EXPORTS)) {
4419                         scan(tree.mods);
4420                         scan(tree.typarams);
4421                         try {
4422                             inSuperType = true;
4423                             scan(tree.extending);
4424                             scan(tree.implementing);
4425                         } finally {
4426                             inSuperType = false;
4427                         }
4428                         scan(tree.defs);
4429                     }
4430                 } finally {
4431                     lint = prevLint;
4432                 }
4433             }
4434             @Override
4435             public void visitTypeApply(JCTypeApply tree) {
4436                 scan(tree.clazz);
4437                 boolean oldInSuperType = inSuperType;
4438                 try {
4439                     inSuperType = false;
4440                     scan(tree.arguments);
4441                 } finally {
4442                     inSuperType = oldInSuperType;
4443                 }
4444             }
4445             @Override
4446             public void visitIdent(JCIdent tree) {
4447                 Symbol sym = TreeInfo.symbol(tree);
4448                 if (sym.kind == TYP && !sym.type.hasTag(TYPEVAR)) {
4449                     checkVisible(tree.pos(), sym, toplevel.packge, inSuperType);
4450                 }
4451             }
4452 
4453             @Override
4454             public void visitSelect(JCFieldAccess tree) {
4455                 Symbol sym = TreeInfo.symbol(tree);
4456                 Symbol sitesym = TreeInfo.symbol(tree.selected);
4457                 if (sym.kind == TYP && sitesym.kind == PCK) {
4458                     checkVisible(tree.pos(), sym, toplevel.packge, inSuperType);
4459                 } else {
4460                     super.visitSelect(tree);
4461                 }
4462             }
4463 
4464             @Override
4465             public void visitAnnotation(JCAnnotation tree) {
4466                 if (tree.attribute.type.tsym.getAnnotation(java.lang.annotation.Documented.class) != null)
4467                     super.visitAnnotation(tree);
4468             }
4469 
4470         }.scan(check);
4471     }
4472         //where:
4473         private ExportsDirective findExport(PackageSymbol pack) {
4474             for (ExportsDirective d : pack.modle.exports) {
4475                 if (d.packge == pack)
4476                     return d;
4477             }
4478 
4479             return null;
4480         }
4481         private boolean isAPISymbol(Symbol sym) {
4482             while (sym.kind != PCK) {
4483                 if ((sym.flags() & Flags.PUBLIC) == 0 && (sym.flags() & Flags.PROTECTED) == 0) {
4484                     return false;
4485                 }
4486                 sym = sym.owner;
4487             }
4488             return true;
4489         }
4490         private void checkVisible(DiagnosticPosition pos, Symbol what, PackageSymbol inPackage, boolean inSuperType) {
4491             if (!isAPISymbol(what) && !inSuperType) { //package private/private element
4492                 log.warning(LintCategory.EXPORTS, pos, Warnings.LeaksNotAccessible(kindName(what), what, what.packge().modle));
4493                 return ;
4494             }
4495 
4496             PackageSymbol whatPackage = what.packge();
4497             ExportsDirective whatExport = findExport(whatPackage);
4498             ExportsDirective inExport = findExport(inPackage);
4499 
4500             if (whatExport == null) { //package not exported:
4501                 log.warning(LintCategory.EXPORTS, pos, Warnings.LeaksNotAccessibleUnexported(kindName(what), what, what.packge().modle));
4502                 return ;
4503             }
4504 
4505             if (whatExport.modules != null) {
4506                 if (inExport.modules == null || !whatExport.modules.containsAll(inExport.modules)) {
4507                     log.warning(LintCategory.EXPORTS, pos, Warnings.LeaksNotAccessibleUnexportedQualified(kindName(what), what, what.packge().modle));
4508                 }
4509             }
4510 
4511             if (whatPackage.modle != inPackage.modle && whatPackage.modle != syms.java_base) {
4512                 //check that relativeTo.modle requires transitive what.modle, somehow:
4513                 List<ModuleSymbol> todo = List.of(inPackage.modle);
4514 
4515                 while (todo.nonEmpty()) {
4516                     ModuleSymbol current = todo.head;
4517                     todo = todo.tail;
4518                     if (current == whatPackage.modle)
4519                         return ; //OK
4520                     if ((current.flags() & Flags.AUTOMATIC_MODULE) != 0)
4521                         continue; //for automatic modules, don't look into their dependencies
4522                     for (RequiresDirective req : current.requires) {
4523                         if (req.isTransitive()) {
4524                             todo = todo.prepend(req.module);
4525                         }
4526                     }
4527                 }
4528 
4529                 log.warning(LintCategory.EXPORTS, pos, Warnings.LeaksNotAccessibleNotRequiredTransitive(kindName(what), what, what.packge().modle));
4530             }
4531         }
4532 
4533     void checkModuleExists(final DiagnosticPosition pos, ModuleSymbol msym) {
4534         if (msym.kind != MDL) {
4535             deferredLintHandler.report(() -> {
4536                 if (lint.isEnabled(LintCategory.MODULE))
4537                     log.warning(LintCategory.MODULE, pos, Warnings.ModuleNotFound(msym));
4538             });
4539         }
4540     }
4541 
4542     void checkPackageExistsForOpens(final DiagnosticPosition pos, PackageSymbol packge) {
4543         if (packge.members().isEmpty() &&
4544             ((packge.flags() & Flags.HAS_RESOURCE) == 0)) {
4545             deferredLintHandler.report(() -> {
4546                 if (lint.isEnabled(LintCategory.OPENS))
4547                     log.warning(pos, Warnings.PackageEmptyOrNotFound(packge));
4548             });
4549         }
4550     }
4551 
4552     void checkModuleRequires(final DiagnosticPosition pos, final RequiresDirective rd) {
4553         if ((rd.module.flags() & Flags.AUTOMATIC_MODULE) != 0) {
4554             deferredLintHandler.report(() -> {
4555                 if (rd.isTransitive() && lint.isEnabled(LintCategory.REQUIRES_TRANSITIVE_AUTOMATIC)) {
4556                     log.warning(pos, Warnings.RequiresTransitiveAutomatic);
4557                 } else if (lint.isEnabled(LintCategory.REQUIRES_AUTOMATIC)) {
4558                     log.warning(pos, Warnings.RequiresAutomatic);
4559                 }
4560             });
4561         }
4562     }
4563 
4564     /**
4565      * Verify the case labels conform to the constraints. Checks constraints related
4566      * combinations of patterns and other labels.
4567      *
4568      * @param cases the cases that should be checked.
4569      */
4570     void checkSwitchCaseStructure(List<JCCase> cases) {
4571         boolean wasConstant = false;          // Seen a constant in the same case label
4572         boolean wasDefault = false;           // Seen a default in the same case label
4573         boolean wasNullPattern = false;       // Seen a null pattern in the same case label,
4574                                               //or fall through from a null pattern
4575         boolean wasPattern = false;           // Seen a pattern in the same case label
4576                                               //or fall through from a pattern
4577         boolean wasTypePattern = false;       // Seen a pattern in the same case label
4578                                               //or fall through from a type pattern
4579         boolean wasNonEmptyFallThrough = false;
4580         for (List<JCCase> l = cases; l.nonEmpty(); l = l.tail) {
4581             JCCase c = l.head;
4582             for (JCCaseLabel pat : c.labels) {
4583                 if (pat.isExpression()) {
4584                     JCExpression expr = (JCExpression) pat;
4585                     if (TreeInfo.isNull(expr)) {
4586                         if (wasPattern && !wasTypePattern && !wasNonEmptyFallThrough) {
4587                             log.error(pat.pos(), Errors.FlowsThroughFromPattern);
4588                         }
4589                         wasNullPattern = true;
4590                     } else {
4591                         if (wasPattern && !wasNonEmptyFallThrough) {
4592                             log.error(pat.pos(), Errors.FlowsThroughFromPattern);
4593                         }
4594                         wasConstant = true;
4595                     }
4596                 } else if (pat.hasTag(DEFAULTCASELABEL)) {
4597                     if (wasPattern && !wasNonEmptyFallThrough) {
4598                         log.error(pat.pos(), Errors.FlowsThroughFromPattern);
4599                     }
4600                     wasDefault = true;
4601                 } else {
4602                     boolean isTypePattern = pat.hasTag(BINDINGPATTERN);
4603                     if (wasPattern || wasConstant || wasDefault ||
4604                         (wasNullPattern && (!isTypePattern || wasNonEmptyFallThrough))) {
4605                         log.error(pat.pos(), Errors.FlowsThroughToPattern);
4606                     }
4607                     wasPattern = true;
4608                     wasTypePattern = isTypePattern;
4609                 }
4610             }
4611 
4612             boolean completesNormally = c.caseKind == CaseTree.CaseKind.STATEMENT ? c.completesNormally
4613                                                                                   : false;
4614 
4615             if (c.stats.nonEmpty()) {
4616                 wasConstant = false;
4617                 wasDefault = false;
4618                 wasNullPattern &= completesNormally;
4619                 wasPattern &= completesNormally;
4620                 wasTypePattern &= completesNormally;
4621             }
4622 
4623             wasNonEmptyFallThrough = c.stats.nonEmpty() && completesNormally;
4624         }
4625     }
4626 
4627     /** check if a type is a subtype of Externalizable, if that is available. */
4628     boolean isExternalizable(Type t) {
4629         try {
4630             syms.externalizableType.complete();
4631         }
4632         catch (CompletionFailure e) {
4633             return false;
4634         }
4635         return types.isSubtype(t, syms.externalizableType);
4636     }
4637 
4638     /**
4639      * Check structure of serialization declarations.
4640      */
4641     public void checkSerialStructure(JCClassDecl tree, ClassSymbol c) {
4642         (new SerialTypeVisitor()).visit(c, tree);
4643     }
4644 
4645     /**
4646      * This visitor will warn if a serialization-related field or
4647      * method is declared in a suspicious or incorrect way. In
4648      * particular, it will warn for cases where the runtime
4649      * serialization mechanism will silently ignore a mis-declared
4650      * entity.
4651      *
4652      * Distinguished serialization-related fields and methods:
4653      *
4654      * Methods:
4655      *
4656      * private void writeObject(ObjectOutputStream stream) throws IOException
4657      * ANY-ACCESS-MODIFIER Object writeReplace() throws ObjectStreamException
4658      *
4659      * private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException
4660      * private void readObjectNoData() throws ObjectStreamException
4661      * ANY-ACCESS-MODIFIER Object readResolve() throws ObjectStreamException
4662      *
4663      * Fields:
4664      *
4665      * private static final long serialVersionUID
4666      * private static final ObjectStreamField[] serialPersistentFields
4667      *
4668      * Externalizable: methods defined on the interface
4669      * public void writeExternal(ObjectOutput) throws IOException
4670      * public void readExternal(ObjectInput) throws IOException
4671      */
4672     private class SerialTypeVisitor extends ElementKindVisitor14<Void, JCClassDecl> {
4673         SerialTypeVisitor() {
4674             this.lint = Check.this.lint;
4675         }
4676 
4677         private static final Set<String> serialMethodNames =
4678             Set.of("writeObject", "writeReplace",
4679                    "readObject",  "readObjectNoData",
4680                    "readResolve");
4681 
4682         private static final Set<String> serialFieldNames =
4683             Set.of("serialVersionUID", "serialPersistentFields");
4684 
4685         // Type of serialPersistentFields
4686         private final Type OSF_TYPE = new Type.ArrayType(syms.objectStreamFieldType, syms.arrayClass);
4687 
4688         Lint lint;
4689 
4690         @Override
4691         public Void defaultAction(Element e, JCClassDecl p) {
4692             throw new IllegalArgumentException(Objects.requireNonNullElse(e.toString(), ""));
4693         }
4694 
4695         @Override
4696         public Void visitType(TypeElement e, JCClassDecl p) {
4697             runUnderLint(e, p, (symbol, param) -> super.visitType(symbol, param));
4698             return null;
4699         }
4700 
4701         @Override
4702         public Void visitTypeAsClass(TypeElement e,
4703                                      JCClassDecl p) {
4704             // Anonymous classes filtered out by caller.
4705 
4706             ClassSymbol c = (ClassSymbol)e;
4707 
4708             checkCtorAccess(p, c);
4709 
4710             // Check for missing serialVersionUID; check *not* done
4711             // for enums or records.
4712             VarSymbol svuidSym = null;
4713             for (Symbol sym : c.members().getSymbolsByName(names.serialVersionUID)) {
4714                 if (sym.kind == VAR) {
4715                     svuidSym = (VarSymbol)sym;
4716                     break;
4717                 }
4718             }
4719 
4720             if (svuidSym == null) {
4721                 log.warning(LintCategory.SERIAL, p.pos(), Warnings.MissingSVUID(c));
4722             }
4723 
4724             // Check for serialPersistentFields to gate checks for
4725             // non-serializable non-transient instance fields
4726             boolean serialPersistentFieldsPresent =
4727                     c.members()
4728                      .getSymbolsByName(names.serialPersistentFields, sym -> sym.kind == VAR)
4729                      .iterator()
4730                      .hasNext();
4731 
4732             // Check declarations of serialization-related methods and
4733             // fields
4734             for(Symbol el : c.getEnclosedElements()) {
4735                 runUnderLint(el, p, (enclosed, tree) -> {
4736                     String name = null;
4737                     switch(enclosed.getKind()) {
4738                     case FIELD -> {
4739                         if (!serialPersistentFieldsPresent) {
4740                             var flags = enclosed.flags();
4741                             if ( ((flags & TRANSIENT) == 0) &&
4742                                  ((flags & STATIC) == 0)) {
4743                                 Type varType = enclosed.asType();
4744                                 if (!canBeSerialized(varType)) {
4745                                     // Note per JLS arrays are
4746                                     // serializable even if the
4747                                     // component type is not.
4748                                     log.warning(LintCategory.SERIAL,
4749                                                 TreeInfo.diagnosticPositionFor(enclosed, tree),
4750                                                 Warnings.NonSerializableInstanceField);
4751                                 } else if (varType.hasTag(ARRAY)) {
4752                                     ArrayType arrayType = (ArrayType)varType;
4753                                     Type elementType = arrayType.elemtype;
4754                                     while (elementType.hasTag(ARRAY)) {
4755                                         arrayType = (ArrayType)elementType;
4756                                         elementType = arrayType.elemtype;
4757                                     }
4758                                     if (!canBeSerialized(elementType)) {
4759                                         log.warning(LintCategory.SERIAL,
4760                                                     TreeInfo.diagnosticPositionFor(enclosed, tree),
4761                                                     Warnings.NonSerializableInstanceFieldArray(elementType));
4762                                     }
4763                                 }
4764                             }
4765                         }
4766 
4767                         name = enclosed.getSimpleName().toString();
4768                         if (serialFieldNames.contains(name)) {
4769                             VarSymbol field = (VarSymbol)enclosed;
4770                             switch (name) {
4771                             case "serialVersionUID"       ->  checkSerialVersionUID(tree, e, field);
4772                             case "serialPersistentFields" ->  checkSerialPersistentFields(tree, e, field);
4773                             default -> throw new AssertionError();
4774                             }
4775                         }
4776                     }
4777 
4778                     // Correctly checking the serialization-related
4779                     // methods is subtle. For the methods declared to be
4780                     // private or directly declared in the class, the
4781                     // enclosed elements of the class can be checked in
4782                     // turn. However, writeReplace and readResolve can be
4783                     // declared in a superclass and inherited. Note that
4784                     // the runtime lookup walks the superclass chain
4785                     // looking for writeReplace/readResolve via
4786                     // Class.getDeclaredMethod. This differs from calling
4787                     // Elements.getAllMembers(TypeElement) as the latter
4788                     // will also pull in default methods from
4789                     // superinterfaces. In other words, the runtime checks
4790                     // (which long predate default methods on interfaces)
4791                     // do not admit the possibility of inheriting methods
4792                     // this way, a difference from general inheritance.
4793 
4794                     // The current implementation just checks the enclosed
4795                     // elements and does not directly check the inherited
4796                     // methods. If all the types are being checked this is
4797                     // less of a concern; however, there are cases that
4798                     // could be missed. In particular, readResolve and
4799                     // writeReplace could, in principle, by inherited from
4800                     // a non-serializable superclass and thus not checked
4801                     // even if compiled with a serializable child class.
4802                     case METHOD -> {
4803                         var method = (MethodSymbol)enclosed;
4804                         name = method.getSimpleName().toString();
4805                         if (serialMethodNames.contains(name)) {
4806                             switch (name) {
4807                             case "writeObject"      -> checkWriteObject(tree, e, method);
4808                             case "writeReplace"     -> checkWriteReplace(tree,e, method);
4809                             case "readObject"       -> checkReadObject(tree,e, method);
4810                             case "readObjectNoData" -> checkReadObjectNoData(tree, e, method);
4811                             case "readResolve"      -> checkReadResolve(tree, e, method);
4812                             default ->  throw new AssertionError();
4813                             }
4814                         }
4815                     }
4816                     }
4817                 });
4818             }
4819 
4820             return null;
4821         }
4822 
4823         boolean canBeSerialized(Type type) {
4824             return type.isPrimitive() || rs.isSerializable(type);
4825         }
4826 
4827         /**
4828          * Check that Externalizable class needs a public no-arg
4829          * constructor.
4830          *
4831          * Check that a Serializable class has access to the no-arg
4832          * constructor of its first nonserializable superclass.
4833          */
4834         private void checkCtorAccess(JCClassDecl tree, ClassSymbol c) {
4835             if (isExternalizable(c.type)) {
4836                 for(var sym : c.getEnclosedElements()) {
4837                     if (sym.isConstructor() &&
4838                         ((sym.flags() & PUBLIC) == PUBLIC)) {
4839                         if (((MethodSymbol)sym).getParameters().isEmpty()) {
4840                             return;
4841                         }
4842                     }
4843                 }
4844                 log.warning(LintCategory.SERIAL, tree.pos(),
4845                             Warnings.ExternalizableMissingPublicNoArgCtor);
4846             } else {
4847                 // Approximate access to the no-arg constructor up in
4848                 // the superclass chain by checking that the
4849                 // constructor is not private. This may not handle
4850                 // some cross-package situations correctly.
4851                 Type superClass = c.getSuperclass();
4852                 // java.lang.Object is *not* Serializable so this loop
4853                 // should terminate.
4854                 while (rs.isSerializable(superClass) ) {
4855                     try {
4856                         superClass = (Type)((TypeElement)(((DeclaredType)superClass)).asElement()).getSuperclass();
4857                     } catch(ClassCastException cce) {
4858                         return ; // Don't try to recover
4859                     }
4860                 }
4861                 // Non-Serializable super class
4862                 try {
4863                     ClassSymbol supertype = ((ClassSymbol)(((DeclaredType)superClass).asElement()));
4864                     for(var sym : supertype.getEnclosedElements()) {
4865                         if (sym.isConstructor()) {
4866                             MethodSymbol ctor = (MethodSymbol)sym;
4867                             if (ctor.getParameters().isEmpty()) {
4868                                 if (((ctor.flags() & PRIVATE) == PRIVATE) ||
4869                                     // Handle nested classes and implicit this$0
4870                                     (supertype.getNestingKind() == NestingKind.MEMBER &&
4871                                      ((supertype.flags() & STATIC) == 0)))
4872                                     log.warning(LintCategory.SERIAL, tree.pos(),
4873                                                 Warnings.SerializableMissingAccessNoArgCtor(supertype.getQualifiedName()));
4874                             }
4875                         }
4876                     }
4877                 } catch (ClassCastException cce) {
4878                     return ; // Don't try to recover
4879                 }
4880                 return;
4881             }
4882         }
4883 
4884         private void checkSerialVersionUID(JCClassDecl tree, Element e, VarSymbol svuid) {
4885             // To be effective, serialVersionUID must be marked static
4886             // and final, but private is recommended. But alas, in
4887             // practice there are many non-private serialVersionUID
4888             // fields.
4889              if ((svuid.flags() & (STATIC | FINAL)) !=
4890                  (STATIC | FINAL)) {
4891                  log.warning(LintCategory.SERIAL,
4892                              TreeInfo.diagnosticPositionFor(svuid, tree),
4893                              Warnings.ImproperSVUID((Symbol)e));
4894              }
4895 
4896              // check svuid has type long
4897              if (!svuid.type.hasTag(LONG)) {
4898                  log.warning(LintCategory.SERIAL,
4899                              TreeInfo.diagnosticPositionFor(svuid, tree),
4900                              Warnings.LongSVUID((Symbol)e));
4901              }
4902 
4903              if (svuid.getConstValue() == null)
4904                  log.warning(LintCategory.SERIAL,
4905                             TreeInfo.diagnosticPositionFor(svuid, tree),
4906                              Warnings.ConstantSVUID((Symbol)e));
4907         }
4908 
4909         private void checkSerialPersistentFields(JCClassDecl tree, Element e, VarSymbol spf) {
4910             // To be effective, serialPersisentFields must be private, static, and final.
4911              if ((spf.flags() & (PRIVATE | STATIC | FINAL)) !=
4912                  (PRIVATE | STATIC | FINAL)) {
4913                  log.warning(LintCategory.SERIAL,
4914                              TreeInfo.diagnosticPositionFor(spf, tree), Warnings.ImproperSPF);
4915              }
4916 
4917              if (!types.isSameType(spf.type, OSF_TYPE)) {
4918                  log.warning(LintCategory.SERIAL,
4919                              TreeInfo.diagnosticPositionFor(spf, tree), Warnings.OSFArraySPF);
4920              }
4921 
4922             if (isExternalizable((Type)(e.asType()))) {
4923                 log.warning(LintCategory.SERIAL, tree.pos(),
4924                             Warnings.IneffectualSerialFieldExternalizable);
4925             }
4926 
4927             // Warn if serialPersistentFields is initialized to a
4928             // literal null.
4929             JCTree spfDecl = TreeInfo.declarationFor(spf, tree);
4930             if (spfDecl != null && spfDecl.getTag() == VARDEF) {
4931                 JCVariableDecl variableDef = (JCVariableDecl) spfDecl;
4932                 JCExpression initExpr = variableDef.init;
4933                  if (initExpr != null && TreeInfo.isNull(initExpr)) {
4934                      log.warning(LintCategory.SERIAL, initExpr.pos(),
4935                                  Warnings.SPFNullInit);
4936                  }
4937             }
4938         }
4939 
4940         private void checkWriteObject(JCClassDecl tree, Element e, MethodSymbol method) {
4941             // The "synchronized" modifier is seen in the wild on
4942             // readObject and writeObject methods and is generally
4943             // innocuous.
4944 
4945             // private void writeObject(ObjectOutputStream stream) throws IOException
4946             checkPrivateNonStaticMethod(tree, method);
4947             checkReturnType(tree, e, method, syms.voidType);
4948             checkOneArg(tree, e, method, syms.objectOutputStreamType);
4949             checkExceptions(tree, e, method, syms.ioExceptionType);
4950             checkExternalizable(tree, e, method);
4951         }
4952 
4953         private void checkWriteReplace(JCClassDecl tree, Element e, MethodSymbol method) {
4954             // ANY-ACCESS-MODIFIER Object writeReplace() throws
4955             // ObjectStreamException
4956 
4957             // Excluding abstract, could have a more complicated
4958             // rule based on abstract-ness of the class
4959             checkConcreteInstanceMethod(tree, e, method);
4960             checkReturnType(tree, e, method, syms.objectType);
4961             checkNoArgs(tree, e, method);
4962             checkExceptions(tree, e, method, syms.objectStreamExceptionType);
4963         }
4964 
4965         private void checkReadObject(JCClassDecl tree, Element e, MethodSymbol method) {
4966             // The "synchronized" modifier is seen in the wild on
4967             // readObject and writeObject methods and is generally
4968             // innocuous.
4969 
4970             // private void readObject(ObjectInputStream stream)
4971             //   throws IOException, ClassNotFoundException
4972             checkPrivateNonStaticMethod(tree, method);
4973             checkReturnType(tree, e, method, syms.voidType);
4974             checkOneArg(tree, e, method, syms.objectInputStreamType);
4975             checkExceptions(tree, e, method, syms.ioExceptionType, syms.classNotFoundExceptionType);
4976             checkExternalizable(tree, e, method);
4977         }
4978 
4979         private void checkReadObjectNoData(JCClassDecl tree, Element e, MethodSymbol method) {
4980             // private void readObjectNoData() throws ObjectStreamException
4981             checkPrivateNonStaticMethod(tree, method);
4982             checkReturnType(tree, e, method, syms.voidType);
4983             checkNoArgs(tree, e, method);
4984             checkExceptions(tree, e, method, syms.objectStreamExceptionType);
4985             checkExternalizable(tree, e, method);
4986         }
4987 
4988         private void checkReadResolve(JCClassDecl tree, Element e, MethodSymbol method) {
4989             // ANY-ACCESS-MODIFIER Object readResolve()
4990             // throws ObjectStreamException
4991 
4992             // Excluding abstract, could have a more complicated
4993             // rule based on abstract-ness of the class
4994             checkConcreteInstanceMethod(tree, e, method);
4995             checkReturnType(tree,e, method, syms.objectType);
4996             checkNoArgs(tree, e, method);
4997             checkExceptions(tree, e, method, syms.objectStreamExceptionType);
4998         }
4999 
5000         void checkPrivateNonStaticMethod(JCClassDecl tree, MethodSymbol method) {
5001             var flags = method.flags();
5002             if ((flags & PRIVATE) == 0) {
5003                 log.warning(LintCategory.SERIAL,
5004                             TreeInfo.diagnosticPositionFor(method, tree),
5005                             Warnings.SerialMethodNotPrivate(method.getSimpleName()));
5006             }
5007 
5008             if ((flags & STATIC) != 0) {
5009                 log.warning(LintCategory.SERIAL,
5010                             TreeInfo.diagnosticPositionFor(method, tree),
5011                             Warnings.SerialMethodStatic(method.getSimpleName()));
5012             }
5013         }
5014 
5015         /**
5016          * Per section 1.12 "Serialization of Enum Constants" of
5017          * the serialization specification, due to the special
5018          * serialization handling of enums, any writeObject,
5019          * readObject, writeReplace, and readResolve methods are
5020          * ignored as are serialPersistentFields and
5021          * serialVersionUID fields.
5022          */
5023         @Override
5024         public Void visitTypeAsEnum(TypeElement e,
5025                                     JCClassDecl p) {
5026             for(Element el : e.getEnclosedElements()) {
5027                 runUnderLint(el, p, (enclosed, tree) -> {
5028                     String name = enclosed.getSimpleName().toString();
5029                     switch(enclosed.getKind()) {
5030                     case FIELD -> {
5031                         if (serialFieldNames.contains(name)) {
5032                             log.warning(LintCategory.SERIAL, tree.pos(),
5033                                         Warnings.IneffectualSerialFieldEnum(name));
5034                         }
5035                     }
5036 
5037                     case METHOD -> {
5038                         if (serialMethodNames.contains(name)) {
5039                             log.warning(LintCategory.SERIAL, tree.pos(),
5040                                         Warnings.IneffectualSerialMethodEnum(name));
5041                         }
5042                     }
5043                     }
5044                 });
5045             }
5046             return null;
5047         }
5048 
5049         /**
5050          * Most serialization-related fields and methods on interfaces
5051          * are ineffectual or problematic.
5052          */
5053         @Override
5054         public Void visitTypeAsInterface(TypeElement e,
5055                                          JCClassDecl p) {
5056             for(Element el : e.getEnclosedElements()) {
5057                 runUnderLint(el, p, (enclosed, tree) -> {
5058                     String name = null;
5059                     switch(enclosed.getKind()) {
5060                     case FIELD -> {
5061                         var field = (VarSymbol)enclosed;
5062                         name = field.getSimpleName().toString();
5063                         switch(name) {
5064                         case "serialPersistentFields" -> {
5065                             log.warning(LintCategory.SERIAL,
5066                                         TreeInfo.diagnosticPositionFor(field, tree),
5067                                         Warnings.IneffectualSerialFieldInterface);
5068                         }
5069 
5070                         case "serialVersionUID" -> {
5071                             checkSerialVersionUID(tree, e, field);
5072                         }
5073                         }
5074                     }
5075 
5076                     case METHOD -> {
5077                         var method = (MethodSymbol)enclosed;
5078                         name = enclosed.getSimpleName().toString();
5079                         if (serialMethodNames.contains(name)) {
5080                             switch (name) {
5081                             case
5082                                 "readObject",
5083                                 "readObjectNoData",
5084                                 "writeObject"      -> checkPrivateMethod(tree, e, method);
5085 
5086                             case
5087                                 "writeReplace",
5088                                 "readResolve"      -> checkDefaultIneffective(tree, e, method);
5089 
5090                             default ->  throw new AssertionError();
5091                             }
5092 
5093                         }
5094                     }
5095                     }
5096                 });
5097             }
5098 
5099             return null;
5100         }
5101 
5102         private void checkPrivateMethod(JCClassDecl tree,
5103                                         Element e,
5104                                         MethodSymbol method) {
5105             if ((method.flags() & PRIVATE) == 0) {
5106                 log.warning(LintCategory.SERIAL,
5107                             TreeInfo.diagnosticPositionFor(method, tree),
5108                             Warnings.NonPrivateMethodWeakerAccess);
5109             }
5110         }
5111 
5112         private void checkDefaultIneffective(JCClassDecl tree,
5113                                              Element e,
5114                                              MethodSymbol method) {
5115             if ((method.flags() & DEFAULT) == DEFAULT) {
5116                 log.warning(LintCategory.SERIAL,
5117                             TreeInfo.diagnosticPositionFor(method, tree),
5118                             Warnings.DefaultIneffective);
5119 
5120             }
5121         }
5122 
5123         @Override
5124         public Void visitTypeAsAnnotationType(TypeElement e,
5125                                               JCClassDecl p) {
5126             // Per the JLS, annotation types are not serializeable
5127             return null;
5128         }
5129 
5130         /**
5131          * From the Java Object Serialization Specification, 1.13
5132          * Serialization of Records:
5133          *
5134          * "The process by which record objects are serialized or
5135          * externalized cannot be customized; any class-specific
5136          * writeObject, readObject, readObjectNoData, writeExternal,
5137          * and readExternal methods defined by record classes are
5138          * ignored during serialization and deserialization. However,
5139          * a substitute object to be serialized or a designate
5140          * replacement may be specified, by the writeReplace and
5141          * readResolve methods, respectively. Any
5142          * serialPersistentFields field declaration is
5143          * ignored. Documenting serializable fields and data for
5144          * record classes is unnecessary, since there is no variation
5145          * in the serial form, other than whether a substitute or
5146          * replacement object is used. The serialVersionUID of a
5147          * record class is 0L unless explicitly declared. The
5148          * requirement for matching serialVersionUID values is waived
5149          * for record classes."
5150          */
5151         @Override
5152         public Void visitTypeAsRecord(TypeElement e,
5153                                       JCClassDecl p) {
5154             for(Element el : e.getEnclosedElements()) {
5155                 runUnderLint(el, p, (enclosed, tree) -> {
5156                     String name = enclosed.getSimpleName().toString();
5157                     switch(enclosed.getKind()) {
5158                     case FIELD -> {
5159                         switch(name) {
5160                         case "serialPersistentFields" -> {
5161                             log.warning(LintCategory.SERIAL, tree.pos(),
5162                                         Warnings.IneffectualSerialFieldRecord);
5163                         }
5164 
5165                         case "serialVersionUID" -> {
5166                             // Could generate additional warning that
5167                             // svuid value is not checked to match for
5168                             // records.
5169                             checkSerialVersionUID(tree, e, (VarSymbol)enclosed);
5170                         }
5171 
5172                         }
5173                     }
5174 
5175                     case METHOD -> {
5176                         var method = (MethodSymbol)enclosed;
5177                         switch(name) {
5178                         case "writeReplace" -> checkWriteReplace(tree, e, method);
5179                         case "readResolve"  -> checkReadResolve(tree, e, method);
5180                         default -> {
5181                             if (serialMethodNames.contains(name)) {
5182                                 log.warning(LintCategory.SERIAL, tree.pos(),
5183                                             Warnings.IneffectualSerialMethodRecord(name));
5184                             }
5185                         }
5186                         }
5187 
5188                     }
5189                     }
5190                 });
5191             }
5192             return null;
5193         }
5194 
5195         void checkConcreteInstanceMethod(JCClassDecl tree,
5196                                          Element enclosing,
5197                                          MethodSymbol method) {
5198             if ((method.flags() & (STATIC | ABSTRACT)) != 0) {
5199                     log.warning(LintCategory.SERIAL,
5200                                 TreeInfo.diagnosticPositionFor(method, tree),
5201                                 Warnings.SerialConcreteInstanceMethod(method.getSimpleName()));
5202             }
5203         }
5204 
5205         private void checkReturnType(JCClassDecl tree,
5206                                      Element enclosing,
5207                                      MethodSymbol method,
5208                                      Type expectedReturnType) {
5209             // Note: there may be complications checking writeReplace
5210             // and readResolve since they return Object and could, in
5211             // principle, have covariant overrides and any synthetic
5212             // bridge method would not be represented here for
5213             // checking.
5214             Type rtype = method.getReturnType();
5215             if (!types.isSameType(expectedReturnType, rtype)) {
5216                 log.warning(LintCategory.SERIAL,
5217                             TreeInfo.diagnosticPositionFor(method, tree),
5218                             Warnings.SerialMethodUnexpectedReturnType(method.getSimpleName(),
5219                                                                       rtype, expectedReturnType));
5220             }
5221         }
5222 
5223         private void checkOneArg(JCClassDecl tree,
5224                                  Element enclosing,
5225                                  MethodSymbol method,
5226                                  Type expectedType) {
5227             String name = method.getSimpleName().toString();
5228 
5229             var parameters= method.getParameters();
5230 
5231             if (parameters.size() != 1) {
5232                 log.warning(LintCategory.SERIAL,
5233                             TreeInfo.diagnosticPositionFor(method, tree),
5234                             Warnings.SerialMethodOneArg(method.getSimpleName(), parameters.size()));
5235                 return;
5236             }
5237 
5238             Type parameterType = parameters.get(0).asType();
5239             if (!types.isSameType(parameterType, expectedType)) {
5240                 log.warning(LintCategory.SERIAL,
5241                             TreeInfo.diagnosticPositionFor(method, tree),
5242                             Warnings.SerialMethodParameterType(method.getSimpleName(),
5243                                                                expectedType,
5244                                                                parameterType));
5245             }
5246         }
5247 
5248         private void checkNoArgs(JCClassDecl tree, Element enclosing, MethodSymbol method) {
5249             var parameters = method.getParameters();
5250             if (!parameters.isEmpty()) {
5251                 log.warning(LintCategory.SERIAL,
5252                             TreeInfo.diagnosticPositionFor(parameters.get(0), tree),
5253                             Warnings.SerialMethodNoArgs(method.getSimpleName()));
5254             }
5255         }
5256 
5257         private void checkExternalizable(JCClassDecl tree, Element enclosing, MethodSymbol method) {
5258             // If the enclosing class is externalizable, warn for the method
5259             if (isExternalizable((Type)enclosing.asType())) {
5260                 log.warning(LintCategory.SERIAL, tree.pos(),
5261                             Warnings.IneffectualSerialMethodExternalizable(method.getSimpleName()));
5262             }
5263             return;
5264         }
5265 
5266         private void checkExceptions(JCClassDecl tree,
5267                                      Element enclosing,
5268                                      MethodSymbol method,
5269                                      Type... declaredExceptions) {
5270             for (Type thrownType: method.getThrownTypes()) {
5271                 // For each exception in the throws clause of the
5272                 // method, if not an Error and not a RuntimeException,
5273                 // check if the exception is a subtype of a declared
5274                 // exception from the throws clause of the
5275                 // serialization method in question.
5276                 if (types.isSubtype(thrownType, syms.runtimeExceptionType) ||
5277                     types.isSubtype(thrownType, syms.errorType) ) {
5278                     continue;
5279                 } else {
5280                     boolean declared = false;
5281                     for (Type declaredException : declaredExceptions) {
5282                         if (types.isSubtype(thrownType, declaredException)) {
5283                             declared = true;
5284                             continue;
5285                         }
5286                     }
5287                     if (!declared) {
5288                         log.warning(LintCategory.SERIAL,
5289                                     TreeInfo.diagnosticPositionFor(method, tree),
5290                                     Warnings.SerialMethodUnexpectedException(method.getSimpleName(),
5291                                                                              thrownType));
5292                     }
5293                 }
5294             }
5295             return;
5296         }
5297 
5298         private <E extends Element> Void runUnderLint(E symbol, JCClassDecl p, BiConsumer<E, JCClassDecl> task) {
5299             Lint prevLint = lint;
5300             try {
5301                 lint = lint.augment((Symbol) symbol);
5302 
5303                 if (lint.isEnabled(LintCategory.SERIAL)) {
5304                     task.accept(symbol, p);
5305                 }
5306 
5307                 return null;
5308             } finally {
5309                 lint = prevLint;
5310             }
5311         }
5312 
5313     }
5314 
5315 }