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src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java

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 150         Options options = Options.instance(context);
 151         lint = Lint.instance(context);
 152         fileManager = context.get(JavaFileManager.class);
 153 
 154         source = Source.instance(context);
 155         target = Target.instance(context);
 156         warnOnAnyAccessToMembers = options.isSet("warnOnAccessToMembers");
 157 
 158         disablePreviewCheck = false;
 159 
 160         Target target = Target.instance(context);
 161         syntheticNameChar = target.syntheticNameChar();
 162 
 163         profile = Profile.instance(context);
 164         preview = Preview.instance(context);
 165 
 166         allowModules = Feature.MODULES.allowedInSource(source);
 167         allowRecords = Feature.RECORDS.allowedInSource(source);
 168         allowSealed = Feature.SEALED_CLASSES.allowedInSource(source);
 169         allowPrimitivePatterns = preview.isEnabled() && Feature.PRIMITIVE_PATTERNS.allowedInSource(source);

 170     }
 171 
 172     /** Character for synthetic names
 173      */
 174     char syntheticNameChar;
 175 
 176     /** A table mapping flat names of all compiled classes for each module in this run
 177      *  to their symbols; maintained from outside.
 178      */
 179     private Map<Pair<ModuleSymbol, Name>,ClassSymbol> compiled = new HashMap<>();
 180 
 181     /** Are modules allowed
 182      */
 183     private final boolean allowModules;
 184 
 185     /** Are records allowed
 186      */
 187     private final boolean allowRecords;
 188 
 189     /** Are sealed classes allowed
 190      */
 191     private final boolean allowSealed;
 192 
 193     /** Are primitive patterns allowed
 194      */
 195     private final boolean allowPrimitivePatterns;
 196 




 197     /** Whether to force suppression of deprecation and preview warnings.
 198      *  This happens when attributing import statements for JDK 9+.
 199      *  @see Feature#DEPRECATION_ON_IMPORT
 200      */
 201     private boolean importSuppression;
 202 
 203 /* *************************************************************************
 204  * Errors and Warnings
 205  **************************************************************************/
 206 
 207     Lint setLint(Lint newLint) {
 208         Lint prev = lint;
 209         lint = newLint;
 210         return prev;
 211     }
 212 
 213     boolean setImportSuppression(boolean newImportSuppression) {
 214         boolean prev = importSuppression;
 215         importSuppression = newImportSuppression;
 216         return prev;

 711                 args = args.tail;
 712             }
 713         }
 714         return t;
 715     }
 716 
 717     /** Check that type is a reference type, i.e. a class, interface or array type
 718      *  or a type variable.
 719      *  @param pos           Position to be used for error reporting.
 720      *  @param t             The type to be checked.
 721      */
 722     Type checkRefType(DiagnosticPosition pos, Type t) {
 723         if (t.isReference())
 724             return t;
 725         else
 726             return typeTagError(pos,
 727                                 diags.fragment(Fragments.TypeReqRef),
 728                                 t);
 729     }
 730 


























 731     /** Check that each type is a reference type, i.e. a class, interface or array type
 732      *  or a type variable.
 733      *  @param trees         Original trees, used for error reporting.
 734      *  @param types         The types to be checked.
 735      */
 736     List<Type> checkRefTypes(List<JCExpression> trees, List<Type> types) {
 737         List<JCExpression> tl = trees;
 738         for (List<Type> l = types; l.nonEmpty(); l = l.tail) {
 739             l.head = checkRefType(tl.head.pos(), l.head);
 740             tl = tl.tail;
 741         }
 742         return types;
 743     }
 744 
 745     /** Check that type is a null or reference type.
 746      *  @param pos           Position to be used for error reporting.
 747      *  @param t             The type to be checked.
 748      */
 749     Type checkNullOrRefType(DiagnosticPosition pos, Type t) {
 750         if (t.isReference() || t.hasTag(BOT))

1102      *  Warning: we can't use flags() here since this method
1103      *  is called during class enter, when flags() would cause a premature
1104      *  completion.
1105      *  @param flags         The set of modifiers given in a definition.
1106      *  @param sym           The defined symbol.
1107      *  @param tree          The declaration
1108      */
1109     long checkFlags(long flags, Symbol sym, JCTree tree) {
1110         final DiagnosticPosition pos = tree.pos();
1111         long mask;
1112         long implicit = 0;
1113 
1114         switch (sym.kind) {
1115         case VAR:
1116             if (TreeInfo.isReceiverParam(tree))
1117                 mask = ReceiverParamFlags;
1118             else if (sym.owner.kind != TYP)
1119                 mask = LocalVarFlags;
1120             else if ((sym.owner.flags_field & INTERFACE) != 0)
1121                 mask = implicit = InterfaceVarFlags;
1122             else
1123                 mask = VarFlags;









1124             break;
1125         case MTH:
1126             if (sym.name == names.init) {
1127                 if ((sym.owner.flags_field & ENUM) != 0) {
1128                     // enum constructors cannot be declared public or
1129                     // protected and must be implicitly or explicitly
1130                     // private
1131                     implicit = PRIVATE;
1132                     mask = PRIVATE;
1133                 } else
1134                     mask = ConstructorFlags;
1135             }  else if ((sym.owner.flags_field & INTERFACE) != 0) {
1136                 if ((sym.owner.flags_field & ANNOTATION) != 0) {
1137                     mask = AnnotationTypeElementMask;
1138                     implicit = PUBLIC | ABSTRACT;
1139                 } else if ((flags & (DEFAULT | STATIC | PRIVATE)) != 0) {
1140                     mask = InterfaceMethodMask;
1141                     implicit = (flags & PRIVATE) != 0 ? 0 : PUBLIC;
1142                     if ((flags & DEFAULT) != 0) {
1143                         implicit |= ABSTRACT;
1144                     }
1145                 } else {
1146                     mask = implicit = InterfaceMethodFlags;
1147                 }
1148             } else if ((sym.owner.flags_field & RECORD) != 0) {
1149                 mask = RecordMethodFlags;

1150             } else {
1151                 mask = MethodFlags;


1152             }
1153             if ((flags & STRICTFP) != 0) {
1154                 log.warning(tree.pos(), LintWarnings.Strictfp);
1155             }
1156             // Imply STRICTFP if owner has STRICTFP set.
1157             if (((flags|implicit) & Flags.ABSTRACT) == 0 ||
1158                 ((flags) & Flags.DEFAULT) != 0)
1159                 implicit |= sym.owner.flags_field & STRICTFP;
1160             break;
1161         case TYP:
1162             if (sym.owner.kind.matches(KindSelector.VAL_MTH) ||
1163                     (sym.isDirectlyOrIndirectlyLocal() && (flags & ANNOTATION) != 0)) {
1164                 boolean implicitlyStatic = !sym.isAnonymous() &&
1165                         ((flags & RECORD) != 0 || (flags & ENUM) != 0 || (flags & INTERFACE) != 0);
1166                 boolean staticOrImplicitlyStatic = (flags & STATIC) != 0 || implicitlyStatic;
1167                 // local statics are allowed only if records are allowed too
1168                 mask = staticOrImplicitlyStatic && allowRecords && (flags & ANNOTATION) == 0 ? StaticLocalFlags : LocalClassFlags;
1169                 implicit = implicitlyStatic ? STATIC : implicit;
1170             } else if (sym.owner.kind == TYP) {
1171                 // statics in inner classes are allowed only if records are allowed too
1172                 mask = ((flags & STATIC) != 0) && allowRecords && (flags & ANNOTATION) == 0 ? ExtendedMemberStaticClassFlags : ExtendedMemberClassFlags;
1173                 if (sym.owner.owner.kind == PCK ||
1174                     (sym.owner.flags_field & STATIC) != 0) {
1175                     mask |= STATIC;
1176                 } else if (!allowRecords && ((flags & ENUM) != 0 || (flags & RECORD) != 0)) {
1177                     log.error(pos, Errors.StaticDeclarationNotAllowedInInnerClasses);
1178                 }
1179                 // Nested interfaces and enums are always STATIC (Spec ???)
1180                 if ((flags & (INTERFACE | ENUM | RECORD)) != 0 ) implicit = STATIC;
1181             } else {
1182                 mask = ExtendedClassFlags;
1183             }




1184             // Interfaces are always ABSTRACT
1185             if ((flags & INTERFACE) != 0) implicit |= ABSTRACT;
1186 




1187             if ((flags & ENUM) != 0) {
1188                 // enums can't be declared abstract, final, sealed or non-sealed
1189                 mask &= ~(ABSTRACT | FINAL | SEALED | NON_SEALED);
1190                 implicit |= implicitEnumFinalFlag(tree);
1191             }
1192             if ((flags & RECORD) != 0) {
1193                 // records can't be declared abstract
1194                 mask &= ~ABSTRACT;
1195                 implicit |= FINAL;
1196             }
1197             if ((flags & STRICTFP) != 0) {
1198                 log.warning(tree.pos(), LintWarnings.Strictfp);
1199             }
1200             // Imply STRICTFP if owner has STRICTFP set.
1201             implicit |= sym.owner.flags_field & STRICTFP;





1202             break;
1203         default:
1204             throw new AssertionError();
1205         }
1206         long illegal = flags & ExtendedStandardFlags & ~mask;
1207         if (illegal != 0) {
1208             if ((illegal & INTERFACE) != 0) {
1209                 log.error(pos, ((flags & ANNOTATION) != 0) ? Errors.AnnotationDeclNotAllowedHere : Errors.IntfNotAllowedHere);
1210                 mask |= INTERFACE;
1211             }
1212             else {
1213                 log.error(pos,
1214                         Errors.ModNotAllowedHere(asFlagSet(illegal)));
1215             }
1216         }
1217         else if ((sym.kind == TYP ||
1218                   // ISSUE: Disallowing abstract&private is no longer appropriate
1219                   // in the presence of inner classes. Should it be deleted here?
1220                   checkDisjoint(pos, flags,
1221                                 ABSTRACT,
1222                                 PRIVATE | STATIC | DEFAULT))
1223                  &&
1224                  checkDisjoint(pos, flags,
1225                                 STATIC | PRIVATE,
1226                                 DEFAULT)
1227                  &&
1228                  checkDisjoint(pos, flags,
1229                                ABSTRACT | INTERFACE,
1230                                FINAL | NATIVE | SYNCHRONIZED)
1231                  &&
1232                  checkDisjoint(pos, flags,
1233                                PUBLIC,
1234                                PRIVATE | PROTECTED)
1235                  &&
1236                  checkDisjoint(pos, flags,
1237                                PRIVATE,
1238                                PUBLIC | PROTECTED)
1239                  &&
1240                  checkDisjoint(pos, flags,

1241                                FINAL,
1242                                VOLATILE)
1243                  &&
1244                  (sym.kind == TYP ||
1245                   checkDisjoint(pos, flags,
1246                                 ABSTRACT | NATIVE,
1247                                 STRICTFP))
1248                  && checkDisjoint(pos, flags,
1249                                 FINAL,
1250                            SEALED | NON_SEALED)
1251                  && checkDisjoint(pos, flags,
1252                                 SEALED,
1253                            FINAL | NON_SEALED)
1254                  && checkDisjoint(pos, flags,
1255                                 SEALED,
1256                                 ANNOTATION)) {






1257             // skip
1258         }
1259         return flags & (mask | ~ExtendedStandardFlags) | implicit;
1260     }
1261 
1262     /** Determine if this enum should be implicitly final.
1263      *
1264      *  If the enum has no specialized enum constants, it is final.
1265      *
1266      *  If the enum does have specialized enum constants, it is
1267      *  <i>not</i> final.
1268      */
1269     private long implicitEnumFinalFlag(JCTree tree) {
1270         if (!tree.hasTag(CLASSDEF)) return 0;
1271         class SpecialTreeVisitor extends JCTree.Visitor {
1272             boolean specialized;
1273             SpecialTreeVisitor() {
1274                 this.specialized = false;
1275             }
1276 

2033                     return true;
2034                 }
2035             }
2036         }
2037         return false;
2038     }
2039 
2040     /** Check that a given method conforms with any method it overrides.
2041      *  @param tree         The tree from which positions are extracted
2042      *                      for errors.
2043      *  @param m            The overriding method.
2044      */
2045     void checkOverride(Env<AttrContext> env, JCMethodDecl tree, MethodSymbol m) {
2046         ClassSymbol origin = (ClassSymbol)m.owner;
2047         if ((origin.flags() & ENUM) != 0 && names.finalize.equals(m.name)) {
2048             if (m.overrides(syms.enumFinalFinalize, origin, types, false)) {
2049                 log.error(tree.pos(), Errors.EnumNoFinalize);
2050                 return;
2051             }
2052         }





2053         if (allowRecords && origin.isRecord()) {
2054             // let's find out if this is a user defined accessor in which case the @Override annotation is acceptable
2055             Optional<? extends RecordComponent> recordComponent = origin.getRecordComponents().stream()
2056                     .filter(rc -> rc.accessor == tree.sym && (rc.accessor.flags_field & GENERATED_MEMBER) == 0).findFirst();
2057             if (recordComponent.isPresent()) {
2058                 return;
2059             }
2060         }
2061 
2062         for (Type t = origin.type; t.hasTag(CLASS);
2063              t = types.supertype(t)) {
2064             if (t != origin.type) {
2065                 checkOverride(tree, t, origin, m);
2066             }
2067             for (Type t2 : types.interfaces(t)) {
2068                 checkOverride(tree, t2, origin, m);
2069             }
2070         }
2071 
2072         final boolean explicitOverride = m.attribute(syms.overrideType.tsym) != null;

2468     /** Check that all abstract methods implemented by a class are
2469      *  mutually compatible.
2470      *  @param pos          Position to be used for error reporting.
2471      *  @param c            The class whose interfaces are checked.
2472      */
2473     void checkCompatibleSupertypes(DiagnosticPosition pos, Type c) {
2474         List<Type> supertypes = types.interfaces(c);
2475         Type supertype = types.supertype(c);
2476         if (supertype.hasTag(CLASS) &&
2477             (supertype.tsym.flags() & ABSTRACT) != 0)
2478             supertypes = supertypes.prepend(supertype);
2479         for (List<Type> l = supertypes; l.nonEmpty(); l = l.tail) {
2480             if (!l.head.getTypeArguments().isEmpty() &&
2481                 !checkCompatibleAbstracts(pos, l.head, l.head, c))
2482                 return;
2483             for (List<Type> m = supertypes; m != l; m = m.tail)
2484                 if (!checkCompatibleAbstracts(pos, l.head, m.head, c))
2485                     return;
2486         }
2487         checkCompatibleConcretes(pos, c);








2488     }
2489 
2490     /** Check that all non-override equivalent methods accessible from 'site'
2491      *  are mutually compatible (JLS 8.4.8/9.4.1).
2492      *
2493      *  @param pos  Position to be used for error reporting.
2494      *  @param site The class whose methods are checked.
2495      *  @param sym  The method symbol to be checked.
2496      */
2497     void checkOverrideClashes(DiagnosticPosition pos, Type site, MethodSymbol sym) {
2498          ClashFilter cf = new ClashFilter(site);
2499         //for each method m1 that is overridden (directly or indirectly)
2500         //by method 'sym' in 'site'...
2501 
2502         ArrayList<Symbol> symbolsByName = new ArrayList<>();
2503         types.membersClosure(site, false).getSymbolsByName(sym.name, cf).forEach(symbolsByName::add);
2504         for (Symbol m1 : symbolsByName) {
2505             if (!sym.overrides(m1, site.tsym, types, false)) {
2506                 continue;
2507             }

4841                 }
4842             } else {
4843                 Assert.error("Unknown pattern: " + currentPattern.getTag());
4844             }
4845             return false;
4846         }
4847 
4848     /** check if a type is a subtype of Externalizable, if that is available. */
4849     boolean isExternalizable(Type t) {
4850         try {
4851             syms.externalizableType.complete();
4852         } catch (CompletionFailure e) {
4853             return false;
4854         }
4855         return types.isSubtype(t, syms.externalizableType);
4856     }
4857 
4858     /**
4859      * Check structure of serialization declarations.
4860      */
4861     public void checkSerialStructure(JCClassDecl tree, ClassSymbol c) {
4862         (new SerialTypeVisitor()).visit(c, tree);
4863     }
4864 
4865     /**
4866      * This visitor will warn if a serialization-related field or
4867      * method is declared in a suspicious or incorrect way. In
4868      * particular, it will warn for cases where the runtime
4869      * serialization mechanism will silently ignore a mis-declared
4870      * entity.
4871      *
4872      * Distinguished serialization-related fields and methods:
4873      *
4874      * Methods:
4875      *
4876      * private void writeObject(ObjectOutputStream stream) throws IOException
4877      * ANY-ACCESS-MODIFIER Object writeReplace() throws ObjectStreamException
4878      *
4879      * private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException
4880      * private void readObjectNoData() throws ObjectStreamException
4881      * ANY-ACCESS-MODIFIER Object readResolve() throws ObjectStreamException
4882      *
4883      * Fields:
4884      *
4885      * private static final long serialVersionUID
4886      * private static final ObjectStreamField[] serialPersistentFields
4887      *
4888      * Externalizable: methods defined on the interface
4889      * public void writeExternal(ObjectOutput) throws IOException
4890      * public void readExternal(ObjectInput) throws IOException
4891      */
4892     private class SerialTypeVisitor extends ElementKindVisitor14<Void, JCClassDecl> {
4893         SerialTypeVisitor() {

4894             this.lint = Check.this.lint;

4895         }
4896 
4897         private static final Set<String> serialMethodNames =
4898             Set.of("writeObject", "writeReplace",
4899                    "readObject",  "readObjectNoData",
4900                    "readResolve");
4901 
4902         private static final Set<String> serialFieldNames =
4903             Set.of("serialVersionUID", "serialPersistentFields");
4904 
4905         // Type of serialPersistentFields
4906         private final Type OSF_TYPE = new Type.ArrayType(syms.objectStreamFieldType, syms.arrayClass);
4907 
4908         Lint lint;
4909 
4910         @Override
4911         public Void defaultAction(Element e, JCClassDecl p) {
4912             throw new IllegalArgumentException(Objects.requireNonNullElse(e.toString(), ""));
4913         }
4914 
4915         @Override
4916         public Void visitType(TypeElement e, JCClassDecl p) {
4917             runUnderLint(e, p, (symbol, param) -> super.visitType(symbol, param));
4918             return null;
4919         }
4920 
4921         @Override
4922         public Void visitTypeAsClass(TypeElement e,
4923                                      JCClassDecl p) {
4924             // Anonymous classes filtered out by caller.
4925 
4926             ClassSymbol c = (ClassSymbol)e;
4927 
4928             checkCtorAccess(p, c);
4929 
4930             // Check for missing serialVersionUID; check *not* done
4931             // for enums or records.



4932             VarSymbol svuidSym = null;
4933             for (Symbol sym : c.members().getSymbolsByName(names.serialVersionUID)) {
4934                 if (sym.kind == VAR) {
4935                     svuidSym = (VarSymbol)sym;
4936                     break;
4937                 }
4938             }
4939 
4940             if (svuidSym == null) {
4941                 log.warning(p.pos(), LintWarnings.MissingSVUID(c));
4942             }
4943 
4944             // Check for serialPersistentFields to gate checks for
4945             // non-serializable non-transient instance fields
4946             boolean serialPersistentFieldsPresent =
4947                     c.members()
4948                      .getSymbolsByName(names.serialPersistentFields, sym -> sym.kind == VAR)
4949                      .iterator()
4950                      .hasNext();
4951 
4952             // Check declarations of serialization-related methods and
4953             // fields

4954             for(Symbol el : c.getEnclosedElements()) {
4955                 runUnderLint(el, p, (enclosed, tree) -> {
4956                     String name = null;
4957                     switch(enclosed.getKind()) {
4958                     case FIELD -> {
4959                         if (!serialPersistentFieldsPresent) {
4960                             var flags = enclosed.flags();
4961                             if ( ((flags & TRANSIENT) == 0) &&
4962                                  ((flags & STATIC) == 0)) {
4963                                 Type varType = enclosed.asType();
4964                                 if (!canBeSerialized(varType)) {
4965                                     // Note per JLS arrays are
4966                                     // serializable even if the
4967                                     // component type is not.
4968                                     log.warning(
4969                                             TreeInfo.diagnosticPositionFor(enclosed, tree),
4970                                                 LintWarnings.NonSerializableInstanceField);
4971                                 } else if (varType.hasTag(ARRAY)) {
4972                                     ArrayType arrayType = (ArrayType)varType;
4973                                     Type elementType = arrayType.elemtype;

5006                     // Class.getDeclaredMethod. This differs from calling
5007                     // Elements.getAllMembers(TypeElement) as the latter
5008                     // will also pull in default methods from
5009                     // superinterfaces. In other words, the runtime checks
5010                     // (which long predate default methods on interfaces)
5011                     // do not admit the possibility of inheriting methods
5012                     // this way, a difference from general inheritance.
5013 
5014                     // The current implementation just checks the enclosed
5015                     // elements and does not directly check the inherited
5016                     // methods. If all the types are being checked this is
5017                     // less of a concern; however, there are cases that
5018                     // could be missed. In particular, readResolve and
5019                     // writeReplace could, in principle, by inherited from
5020                     // a non-serializable superclass and thus not checked
5021                     // even if compiled with a serializable child class.
5022                     case METHOD -> {
5023                         var method = (MethodSymbol)enclosed;
5024                         name = method.getSimpleName().toString();
5025                         if (serialMethodNames.contains(name)) {
5026                             switch (name) {
5027                             case "writeObject"      -> checkWriteObject(tree, e, method);
5028                             case "writeReplace"     -> checkWriteReplace(tree,e, method);
5029                             case "readObject"       -> checkReadObject(tree,e, method);
5030                             case "readObjectNoData" -> checkReadObjectNoData(tree, e, method);
5031                             case "readResolve"      -> checkReadResolve(tree, e, method);
5032                             default ->  throw new AssertionError();


5033                             }
5034                         }
5035                     }
5036                     }
5037                 });
5038             }
5039 










































5040             return null;
5041         }
5042 
5043         boolean canBeSerialized(Type type) {
5044             return type.isPrimitive() || rs.isSerializable(type);
5045         }
5046 
















5047         /**
5048          * Check that Externalizable class needs a public no-arg
5049          * constructor.
5050          *
5051          * Check that a Serializable class has access to the no-arg
5052          * constructor of its first nonserializable superclass.
5053          */
5054         private void checkCtorAccess(JCClassDecl tree, ClassSymbol c) {
5055             if (isExternalizable(c.type)) {
5056                 for(var sym : c.getEnclosedElements()) {
5057                     if (sym.isConstructor() &&
5058                         ((sym.flags() & PUBLIC) == PUBLIC)) {
5059                         if (((MethodSymbol)sym).getParameters().isEmpty()) {
5060                             return;
5061                         }
5062                     }
5063                 }
5064                 log.warning(tree.pos(),
5065                             LintWarnings.ExternalizableMissingPublicNoArgCtor);
5066             } else {

5143 
5144             if (isExternalizable((Type)(e.asType()))) {
5145                 log.warning(
5146                         TreeInfo.diagnosticPositionFor(spf, tree),
5147                             LintWarnings.IneffectualSerialFieldExternalizable);
5148             }
5149 
5150             // Warn if serialPersistentFields is initialized to a
5151             // literal null.
5152             JCTree spfDecl = TreeInfo.declarationFor(spf, tree);
5153             if (spfDecl != null && spfDecl.getTag() == VARDEF) {
5154                 JCVariableDecl variableDef = (JCVariableDecl) spfDecl;
5155                 JCExpression initExpr = variableDef.init;
5156                  if (initExpr != null && TreeInfo.isNull(initExpr)) {
5157                      log.warning(initExpr.pos(),
5158                                  LintWarnings.SPFNullInit);
5159                  }
5160             }
5161         }
5162 
5163         private void checkWriteObject(JCClassDecl tree, Element e, MethodSymbol method) {
5164             // The "synchronized" modifier is seen in the wild on
5165             // readObject and writeObject methods and is generally
5166             // innocuous.
5167 
5168             // private void writeObject(ObjectOutputStream stream) throws IOException
5169             checkPrivateNonStaticMethod(tree, method);
5170             checkReturnType(tree, e, method, syms.voidType);
5171             checkOneArg(tree, e, method, syms.objectOutputStreamType);
5172             checkExceptions(tree, e, method, syms.ioExceptionType);
5173             checkExternalizable(tree, e, method);
5174         }
5175 
5176         private void checkWriteReplace(JCClassDecl tree, Element e, MethodSymbol method) {
5177             // ANY-ACCESS-MODIFIER Object writeReplace() throws
5178             // ObjectStreamException
5179 
5180             // Excluding abstract, could have a more complicated
5181             // rule based on abstract-ness of the class
5182             checkConcreteInstanceMethod(tree, e, method);
5183             checkReturnType(tree, e, method, syms.objectType);
5184             checkNoArgs(tree, e, method);
5185             checkExceptions(tree, e, method, syms.objectStreamExceptionType);
5186         }
5187 
5188         private void checkReadObject(JCClassDecl tree, Element e, MethodSymbol method) {
5189             // The "synchronized" modifier is seen in the wild on
5190             // readObject and writeObject methods and is generally
5191             // innocuous.
5192 
5193             // private void readObject(ObjectInputStream stream)
5194             //   throws IOException, ClassNotFoundException
5195             checkPrivateNonStaticMethod(tree, method);
5196             checkReturnType(tree, e, method, syms.voidType);
5197             checkOneArg(tree, e, method, syms.objectInputStreamType);
5198             checkExceptions(tree, e, method, syms.ioExceptionType, syms.classNotFoundExceptionType);
5199             checkExternalizable(tree, e, method);
5200         }
5201 
5202         private void checkReadObjectNoData(JCClassDecl tree, Element e, MethodSymbol method) {
5203             // private void readObjectNoData() throws ObjectStreamException
5204             checkPrivateNonStaticMethod(tree, method);
5205             checkReturnType(tree, e, method, syms.voidType);
5206             checkNoArgs(tree, e, method);
5207             checkExceptions(tree, e, method, syms.objectStreamExceptionType);
5208             checkExternalizable(tree, e, method);
5209         }
5210 
5211         private void checkReadResolve(JCClassDecl tree, Element e, MethodSymbol method) {
5212             // ANY-ACCESS-MODIFIER Object readResolve()
5213             // throws ObjectStreamException
5214 
5215             // Excluding abstract, could have a more complicated
5216             // rule based on abstract-ness of the class
5217             checkConcreteInstanceMethod(tree, e, method);
5218             checkReturnType(tree,e, method, syms.objectType);
5219             checkNoArgs(tree, e, method);
5220             checkExceptions(tree, e, method, syms.objectStreamExceptionType);
5221         }
5222 
5223         private void checkWriteExternalRecord(JCClassDecl tree, Element e, MethodSymbol method, boolean isExtern) {
5224             //public void writeExternal(ObjectOutput) throws IOException
5225             checkExternMethodRecord(tree, e, method, syms.objectOutputType, isExtern);
5226         }
5227 
5228         private void checkReadExternalRecord(JCClassDecl tree, Element e, MethodSymbol method, boolean isExtern) {
5229             // public void readExternal(ObjectInput) throws IOException
5230             checkExternMethodRecord(tree, e, method, syms.objectInputType, isExtern);
5231          }
5232 
5233         private void checkExternMethodRecord(JCClassDecl tree, Element e, MethodSymbol method, Type argType,
5234                                              boolean isExtern) {
5235             if (isExtern && isExternMethod(tree, e, method, argType)) {
5236                 log.warning(
5237                         TreeInfo.diagnosticPositionFor(method, tree),
5238                             LintWarnings.IneffectualExternalizableMethodRecord(method.getSimpleName().toString()));
5239             }
5240         }
5241 
5242         void checkPrivateNonStaticMethod(JCClassDecl tree, MethodSymbol method) {
5243             var flags = method.flags();

5244             if ((flags & PRIVATE) == 0) {
5245                 log.warning(
5246                         TreeInfo.diagnosticPositionFor(method, tree),
5247                             LintWarnings.SerialMethodNotPrivate(method.getSimpleName()));

5248             }
5249 
5250             if ((flags & STATIC) != 0) {
5251                 log.warning(
5252                         TreeInfo.diagnosticPositionFor(method, tree),
5253                             LintWarnings.SerialMethodStatic(method.getSimpleName()));

5254             }

5255         }
5256 
5257         /**
5258          * Per section 1.12 "Serialization of Enum Constants" of
5259          * the serialization specification, due to the special
5260          * serialization handling of enums, any writeObject,
5261          * readObject, writeReplace, and readResolve methods are
5262          * ignored as are serialPersistentFields and
5263          * serialVersionUID fields.
5264          */
5265         @Override
5266         public Void visitTypeAsEnum(TypeElement e,
5267                                     JCClassDecl p) {
5268             boolean isExtern = isExternalizable((Type)e.asType());
5269             for(Element el : e.getEnclosedElements()) {
5270                 runUnderLint(el, p, (enclosed, tree) -> {
5271                     String name = enclosed.getSimpleName().toString();
5272                     switch(enclosed.getKind()) {
5273                     case FIELD -> {
5274                         var field = (VarSymbol)enclosed;

5450                     case FIELD -> {
5451                         var field = (VarSymbol)enclosed;
5452                         switch(name) {
5453                         case "serialPersistentFields" -> {
5454                             log.warning(
5455                                     TreeInfo.diagnosticPositionFor(field, tree),
5456                                         LintWarnings.IneffectualSerialFieldRecord);
5457                         }
5458 
5459                         case "serialVersionUID" -> {
5460                             // Could generate additional warning that
5461                             // svuid value is not checked to match for
5462                             // records.
5463                             checkSerialVersionUID(tree, e, field);
5464                         }}
5465                     }
5466 
5467                     case METHOD -> {
5468                         var method = (MethodSymbol)enclosed;
5469                         switch(name) {
5470                         case "writeReplace" -> checkWriteReplace(tree, e, method);
5471                         case "readResolve"  -> checkReadResolve(tree, e, method);
5472 
5473                         case "writeExternal" -> checkWriteExternalRecord(tree, e, method, isExtern);
5474                         case "readExternal"  -> checkReadExternalRecord(tree, e, method, isExtern);
5475 
5476                         default -> {
5477                             if (serialMethodNames.contains(name)) {
5478                                 log.warning(
5479                                         TreeInfo.diagnosticPositionFor(method, tree),
5480                                             LintWarnings.IneffectualSerialMethodRecord(name));
5481                             }
5482                         }}
5483                     }}});
5484             }
5485             return null;
5486         }
5487 
5488         void checkConcreteInstanceMethod(JCClassDecl tree,
5489                                          Element enclosing,
5490                                          MethodSymbol method) {
5491             if ((method.flags() & (STATIC | ABSTRACT)) != 0) {

5492                     log.warning(
5493                             TreeInfo.diagnosticPositionFor(method, tree),
5494                                 LintWarnings.SerialConcreteInstanceMethod(method.getSimpleName()));


5495             }

5496         }
5497 
5498         private void checkReturnType(JCClassDecl tree,
5499                                      Element enclosing,
5500                                      MethodSymbol method,
5501                                      Type expectedReturnType) {
5502             // Note: there may be complications checking writeReplace
5503             // and readResolve since they return Object and could, in
5504             // principle, have covariant overrides and any synthetic
5505             // bridge method would not be represented here for
5506             // checking.
5507             Type rtype = method.getReturnType();
5508             if (!types.isSameType(expectedReturnType, rtype)) {
5509                 log.warning(
5510                         TreeInfo.diagnosticPositionFor(method, tree),

5511                             LintWarnings.SerialMethodUnexpectedReturnType(method.getSimpleName(),
5512                                                                       rtype, expectedReturnType));


5513             }

5514         }
5515 
5516         private void checkOneArg(JCClassDecl tree,
5517                                  Element enclosing,
5518                                  MethodSymbol method,
5519                                  Type expectedType) {
5520             String name = method.getSimpleName().toString();
5521 
5522             var parameters= method.getParameters();
5523 
5524             if (parameters.size() != 1) {
5525                 log.warning(
5526                         TreeInfo.diagnosticPositionFor(method, tree),
5527                             LintWarnings.SerialMethodOneArg(method.getSimpleName(), parameters.size()));
5528                 return;
5529             }
5530 
5531             Type parameterType = parameters.get(0).asType();
5532             if (!types.isSameType(parameterType, expectedType)) {
5533                 log.warning(
5534                         TreeInfo.diagnosticPositionFor(method, tree),
5535                             LintWarnings.SerialMethodParameterType(method.getSimpleName(),
5536                                                                expectedType,
5537                                                                parameterType));

5538             }

5539         }
5540 
5541         private boolean hasExactlyOneArgWithType(JCClassDecl tree,
5542                                                  Element enclosing,
5543                                                  MethodSymbol method,
5544                                                  Type expectedType) {
5545             var parameters = method.getParameters();
5546             return (parameters.size() == 1) &&
5547                 types.isSameType(parameters.get(0).asType(), expectedType);
5548         }
5549 
5550 
5551         private void checkNoArgs(JCClassDecl tree, Element enclosing, MethodSymbol method) {
5552             var parameters = method.getParameters();
5553             if (!parameters.isEmpty()) {
5554                 log.warning(
5555                         TreeInfo.diagnosticPositionFor(parameters.get(0), tree),

5556                             LintWarnings.SerialMethodNoArgs(method.getSimpleName()));


5557             }

5558         }
5559 
5560         private void checkExternalizable(JCClassDecl tree, Element enclosing, MethodSymbol method) {
5561             // If the enclosing class is externalizable, warn for the method
5562             if (isExternalizable((Type)enclosing.asType())) {
5563                 log.warning(
5564                         TreeInfo.diagnosticPositionFor(method, tree),
5565                             LintWarnings.IneffectualSerialMethodExternalizable(method.getSimpleName()));

5566             }
5567             return;
5568         }
5569 
5570         private void checkExceptions(JCClassDecl tree,
5571                                      Element enclosing,
5572                                      MethodSymbol method,
5573                                      Type... declaredExceptions) {
5574             for (Type thrownType: method.getThrownTypes()) {
5575                 // For each exception in the throws clause of the
5576                 // method, if not an Error and not a RuntimeException,
5577                 // check if the exception is a subtype of a declared
5578                 // exception from the throws clause of the
5579                 // serialization method in question.
5580                 if (types.isSubtype(thrownType, syms.runtimeExceptionType) ||
5581                     types.isSubtype(thrownType, syms.errorType) ) {
5582                     continue;
5583                 } else {
5584                     boolean declared = false;
5585                     for (Type declaredException : declaredExceptions) {
5586                         if (types.isSubtype(thrownType, declaredException)) {
5587                             declared = true;
5588                             continue;
5589                         }
5590                     }
5591                     if (!declared) {
5592                         log.warning(
5593                                 TreeInfo.diagnosticPositionFor(method, tree),

5594                                     LintWarnings.SerialMethodUnexpectedException(method.getSimpleName(),
5595                                                                              thrownType));


5596                     }
5597                 }
5598             }
5599             return;
5600         }
5601 
5602         private <E extends Element> Void runUnderLint(E symbol, JCClassDecl p, BiConsumer<E, JCClassDecl> task) {
5603             Lint prevLint = lint;
5604             try {
5605                 lint = lint.augment((Symbol) symbol);
5606 
5607                 if (lint.isEnabled(LintCategory.SERIAL)) {
5608                     task.accept(symbol, p);
5609                 }
5610 
5611                 return null;
5612             } finally {
5613                 lint = prevLint;
5614             }
5615         }
5616 
5617     }
5618 
5619     void checkRequiresIdentity(JCTree tree, Lint lint) {

 150         Options options = Options.instance(context);
 151         lint = Lint.instance(context);
 152         fileManager = context.get(JavaFileManager.class);
 153 
 154         source = Source.instance(context);
 155         target = Target.instance(context);
 156         warnOnAnyAccessToMembers = options.isSet("warnOnAccessToMembers");
 157 
 158         disablePreviewCheck = false;
 159 
 160         Target target = Target.instance(context);
 161         syntheticNameChar = target.syntheticNameChar();
 162 
 163         profile = Profile.instance(context);
 164         preview = Preview.instance(context);
 165 
 166         allowModules = Feature.MODULES.allowedInSource(source);
 167         allowRecords = Feature.RECORDS.allowedInSource(source);
 168         allowSealed = Feature.SEALED_CLASSES.allowedInSource(source);
 169         allowPrimitivePatterns = preview.isEnabled() && Feature.PRIMITIVE_PATTERNS.allowedInSource(source);
 170         allowValueClasses = preview.isEnabled() && Feature.VALUE_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     /** Are modules allowed
 183      */
 184     private final boolean allowModules;
 185 
 186     /** Are records allowed
 187      */
 188     private final boolean allowRecords;
 189 
 190     /** Are sealed classes allowed
 191      */
 192     private final boolean allowSealed;
 193 
 194     /** Are primitive patterns allowed
 195      */
 196     private final boolean allowPrimitivePatterns;
 197 
 198     /** Are value classes allowed
 199      */
 200     private final boolean allowValueClasses;
 201 
 202     /** Whether to force suppression of deprecation and preview warnings.
 203      *  This happens when attributing import statements for JDK 9+.
 204      *  @see Feature#DEPRECATION_ON_IMPORT
 205      */
 206     private boolean importSuppression;
 207 
 208 /* *************************************************************************
 209  * Errors and Warnings
 210  **************************************************************************/
 211 
 212     Lint setLint(Lint newLint) {
 213         Lint prev = lint;
 214         lint = newLint;
 215         return prev;
 216     }
 217 
 218     boolean setImportSuppression(boolean newImportSuppression) {
 219         boolean prev = importSuppression;
 220         importSuppression = newImportSuppression;
 221         return prev;

 716                 args = args.tail;
 717             }
 718         }
 719         return t;
 720     }
 721 
 722     /** Check that type is a reference type, i.e. a class, interface or array type
 723      *  or a type variable.
 724      *  @param pos           Position to be used for error reporting.
 725      *  @param t             The type to be checked.
 726      */
 727     Type checkRefType(DiagnosticPosition pos, Type t) {
 728         if (t.isReference())
 729             return t;
 730         else
 731             return typeTagError(pos,
 732                                 diags.fragment(Fragments.TypeReqRef),
 733                                 t);
 734     }
 735 
 736     /** Check that type is an identity type, i.e. not a value type.
 737      *  When not discernible statically, give it the benefit of doubt
 738      *  and defer to runtime.
 739      *
 740      *  @param pos           Position to be used for error reporting.
 741      *  @param t             The type to be checked.
 742      */
 743     boolean checkIdentityType(DiagnosticPosition pos, Type t) {
 744         if (t.hasTag(TYPEVAR)) {
 745             t = types.skipTypeVars(t, false);
 746         }
 747         if (t.isIntersection()) {
 748             IntersectionClassType ict = (IntersectionClassType)t;
 749             boolean result = true;
 750             for (Type component : ict.getExplicitComponents()) {
 751                 result &= checkIdentityType(pos, component);
 752             }
 753             return result;
 754         }
 755         if (t.isPrimitive() || (t.isValueClass() && !t.tsym.isAbstract())) {
 756             typeTagError(pos, diags.fragment(Fragments.TypeReqIdentity), t);
 757             return false;
 758         }
 759         return true;
 760     }
 761 
 762     /** Check that each type is a reference type, i.e. a class, interface or array type
 763      *  or a type variable.
 764      *  @param trees         Original trees, used for error reporting.
 765      *  @param types         The types to be checked.
 766      */
 767     List<Type> checkRefTypes(List<JCExpression> trees, List<Type> types) {
 768         List<JCExpression> tl = trees;
 769         for (List<Type> l = types; l.nonEmpty(); l = l.tail) {
 770             l.head = checkRefType(tl.head.pos(), l.head);
 771             tl = tl.tail;
 772         }
 773         return types;
 774     }
 775 
 776     /** Check that type is a null or reference type.
 777      *  @param pos           Position to be used for error reporting.
 778      *  @param t             The type to be checked.
 779      */
 780     Type checkNullOrRefType(DiagnosticPosition pos, Type t) {
 781         if (t.isReference() || t.hasTag(BOT))

1133      *  Warning: we can't use flags() here since this method
1134      *  is called during class enter, when flags() would cause a premature
1135      *  completion.
1136      *  @param flags         The set of modifiers given in a definition.
1137      *  @param sym           The defined symbol.
1138      *  @param tree          The declaration
1139      */
1140     long checkFlags(long flags, Symbol sym, JCTree tree) {
1141         final DiagnosticPosition pos = tree.pos();
1142         long mask;
1143         long implicit = 0;
1144 
1145         switch (sym.kind) {
1146         case VAR:
1147             if (TreeInfo.isReceiverParam(tree))
1148                 mask = ReceiverParamFlags;
1149             else if (sym.owner.kind != TYP)
1150                 mask = LocalVarFlags;
1151             else if ((sym.owner.flags_field & INTERFACE) != 0)
1152                 mask = implicit = InterfaceVarFlags;
1153             else {
1154                 boolean isInstanceField = (flags & STATIC) == 0;
1155                 boolean isInstanceFieldOfValueClass = isInstanceField && sym.owner.type.isValueClass();
1156                 boolean isRecordField = isInstanceField && (sym.owner.flags_field & RECORD) != 0;
1157                 if (allowValueClasses && (isInstanceFieldOfValueClass || isRecordField)) {
1158                     implicit |= FINAL | STRICT;
1159                     mask = ValueFieldFlags;
1160                 } else {
1161                     mask = VarFlags;
1162                 }
1163             }
1164             break;
1165         case MTH:
1166             if (sym.name == names.init) {
1167                 if ((sym.owner.flags_field & ENUM) != 0) {
1168                     // enum constructors cannot be declared public or
1169                     // protected and must be implicitly or explicitly
1170                     // private
1171                     implicit = PRIVATE;
1172                     mask = PRIVATE;
1173                 } else
1174                     mask = ConstructorFlags;
1175             }  else if ((sym.owner.flags_field & INTERFACE) != 0) {
1176                 if ((sym.owner.flags_field & ANNOTATION) != 0) {
1177                     mask = AnnotationTypeElementMask;
1178                     implicit = PUBLIC | ABSTRACT;
1179                 } else if ((flags & (DEFAULT | STATIC | PRIVATE)) != 0) {
1180                     mask = InterfaceMethodMask;
1181                     implicit = (flags & PRIVATE) != 0 ? 0 : PUBLIC;
1182                     if ((flags & DEFAULT) != 0) {
1183                         implicit |= ABSTRACT;
1184                     }
1185                 } else {
1186                     mask = implicit = InterfaceMethodFlags;
1187                 }
1188             } else if ((sym.owner.flags_field & RECORD) != 0) {
1189                 mask = ((sym.owner.flags_field & VALUE_CLASS) != 0 && (flags & Flags.STATIC) == 0) ?
1190                         RecordMethodFlags & ~SYNCHRONIZED : RecordMethodFlags;
1191             } else {
1192                 // value objects do not have an associated monitor/lock
1193                 mask = ((sym.owner.flags_field & VALUE_CLASS) != 0 && (flags & Flags.STATIC) == 0) ?
1194                         MethodFlags & ~SYNCHRONIZED : MethodFlags;
1195             }
1196             if ((flags & STRICTFP) != 0) {
1197                 log.warning(tree.pos(), LintWarnings.Strictfp);
1198             }
1199             // Imply STRICTFP if owner has STRICTFP set.
1200             if (((flags|implicit) & Flags.ABSTRACT) == 0 ||
1201                 ((flags) & Flags.DEFAULT) != 0)
1202                 implicit |= sym.owner.flags_field & STRICTFP;
1203             break;
1204         case TYP:
1205             if (sym.owner.kind.matches(KindSelector.VAL_MTH) ||
1206                     (sym.isDirectlyOrIndirectlyLocal() && (flags & ANNOTATION) != 0)) {
1207                 boolean implicitlyStatic = !sym.isAnonymous() &&
1208                         ((flags & RECORD) != 0 || (flags & ENUM) != 0 || (flags & INTERFACE) != 0);
1209                 boolean staticOrImplicitlyStatic = (flags & STATIC) != 0 || implicitlyStatic;
1210                 // local statics are allowed only if records are allowed too
1211                 mask = staticOrImplicitlyStatic && allowRecords && (flags & ANNOTATION) == 0 ? ExtendedStaticLocalClassFlags : ExtendedLocalClassFlags;
1212                 implicit = implicitlyStatic ? STATIC : implicit;
1213             } else if (sym.owner.kind == TYP) {
1214                 // statics in inner classes are allowed only if records are allowed too
1215                 mask = ((flags & STATIC) != 0) && allowRecords && (flags & ANNOTATION) == 0 ? ExtendedMemberStaticClassFlags : ExtendedMemberClassFlags;
1216                 if (sym.owner.owner.kind == PCK ||
1217                     (sym.owner.flags_field & STATIC) != 0) {
1218                     mask |= STATIC;
1219                 } else if (!allowRecords && ((flags & ENUM) != 0 || (flags & RECORD) != 0)) {
1220                     log.error(pos, Errors.StaticDeclarationNotAllowedInInnerClasses);
1221                 }
1222                 // Nested interfaces and enums are always STATIC (Spec ???)
1223                 if ((flags & (INTERFACE | ENUM | RECORD)) != 0 ) implicit = STATIC;
1224             } else {
1225                 mask = ExtendedClassFlags;
1226             }
1227             if ((flags & (VALUE_CLASS | SEALED | ABSTRACT)) == (VALUE_CLASS | SEALED) ||
1228                 (flags & (VALUE_CLASS | NON_SEALED | ABSTRACT)) == (VALUE_CLASS | NON_SEALED)) {
1229                 log.error(pos, Errors.NonAbstractValueClassCantBeSealedOrNonSealed);
1230             }
1231             // Interfaces are always ABSTRACT
1232             if ((flags & INTERFACE) != 0) implicit |= ABSTRACT;
1233 
1234             if ((flags & (INTERFACE | VALUE_CLASS)) == 0) {
1235                 implicit |= IDENTITY_TYPE;
1236             }
1237 
1238             if ((flags & ENUM) != 0) {
1239                 // enums can't be declared abstract, final, sealed or non-sealed or value
1240                 mask &= ~(ABSTRACT | FINAL | SEALED | NON_SEALED | VALUE_CLASS);
1241                 implicit |= implicitEnumFinalFlag(tree);
1242             }
1243             if ((flags & RECORD) != 0) {
1244                 // records can't be declared abstract
1245                 mask &= ~ABSTRACT;
1246                 implicit |= FINAL;
1247             }
1248             if ((flags & STRICTFP) != 0) {
1249                 log.warning(tree.pos(), LintWarnings.Strictfp);
1250             }
1251             // Imply STRICTFP if owner has STRICTFP set.
1252             implicit |= sym.owner.flags_field & STRICTFP;
1253 
1254             // concrete value classes are implicitly final
1255             if ((flags & (ABSTRACT | INTERFACE | VALUE_CLASS)) == VALUE_CLASS) {
1256                 implicit |= FINAL;
1257             }
1258             break;
1259         default:
1260             throw new AssertionError();
1261         }
1262         long illegal = flags & ExtendedStandardFlags & ~mask;
1263         if (illegal != 0) {
1264             if ((illegal & INTERFACE) != 0) {
1265                 log.error(pos, ((flags & ANNOTATION) != 0) ? Errors.AnnotationDeclNotAllowedHere : Errors.IntfNotAllowedHere);
1266                 mask |= INTERFACE;
1267             }
1268             else {
1269                 log.error(pos,
1270                         Errors.ModNotAllowedHere(asFlagSet(illegal)));
1271             }
1272         } else if ((sym.kind == TYP ||

1273                   // ISSUE: Disallowing abstract&private is no longer appropriate
1274                   // in the presence of inner classes. Should it be deleted here?
1275                   checkDisjoint(pos, flags,
1276                                 ABSTRACT,
1277                                 PRIVATE | STATIC | DEFAULT))
1278                  &&
1279                  checkDisjoint(pos, flags,
1280                                 STATIC | PRIVATE,
1281                                 DEFAULT)
1282                  &&
1283                  checkDisjoint(pos, flags,
1284                                ABSTRACT | INTERFACE,
1285                                FINAL | NATIVE | SYNCHRONIZED)
1286                  &&
1287                  checkDisjoint(pos, flags,
1288                                PUBLIC,
1289                                PRIVATE | PROTECTED)
1290                  &&
1291                  checkDisjoint(pos, flags,
1292                                PRIVATE,
1293                                PUBLIC | PROTECTED)
1294                  &&
1295                  // we are using `implicit` here as instance fields of value classes are implicitly final
1296                  checkDisjoint(pos, flags | implicit,
1297                                FINAL,
1298                                VOLATILE)
1299                  &&
1300                  (sym.kind == TYP ||
1301                   checkDisjoint(pos, flags,
1302                                 ABSTRACT | NATIVE,
1303                                 STRICTFP))
1304                  && checkDisjoint(pos, flags,
1305                                 FINAL,
1306                            SEALED | NON_SEALED)
1307                  && checkDisjoint(pos, flags,
1308                                 SEALED,
1309                            FINAL | NON_SEALED)
1310                  && checkDisjoint(pos, flags,
1311                                 SEALED,
1312                                 ANNOTATION)
1313                 && checkDisjoint(pos, flags,
1314                                 VALUE_CLASS,
1315                                 ANNOTATION)
1316                 && checkDisjoint(pos, flags,
1317                                 VALUE_CLASS,
1318                                 INTERFACE) ) {
1319             // skip
1320         }
1321         return flags & (mask | ~ExtendedStandardFlags) | implicit;
1322     }
1323 
1324     /** Determine if this enum should be implicitly final.
1325      *
1326      *  If the enum has no specialized enum constants, it is final.
1327      *
1328      *  If the enum does have specialized enum constants, it is
1329      *  <i>not</i> final.
1330      */
1331     private long implicitEnumFinalFlag(JCTree tree) {
1332         if (!tree.hasTag(CLASSDEF)) return 0;
1333         class SpecialTreeVisitor extends JCTree.Visitor {
1334             boolean specialized;
1335             SpecialTreeVisitor() {
1336                 this.specialized = false;
1337             }
1338 

2095                     return true;
2096                 }
2097             }
2098         }
2099         return false;
2100     }
2101 
2102     /** Check that a given method conforms with any method it overrides.
2103      *  @param tree         The tree from which positions are extracted
2104      *                      for errors.
2105      *  @param m            The overriding method.
2106      */
2107     void checkOverride(Env<AttrContext> env, JCMethodDecl tree, MethodSymbol m) {
2108         ClassSymbol origin = (ClassSymbol)m.owner;
2109         if ((origin.flags() & ENUM) != 0 && names.finalize.equals(m.name)) {
2110             if (m.overrides(syms.enumFinalFinalize, origin, types, false)) {
2111                 log.error(tree.pos(), Errors.EnumNoFinalize);
2112                 return;
2113             }
2114         }
2115         if (allowValueClasses && origin.isValueClass() && names.finalize.equals(m.name)) {
2116             if (m.overrides(syms.objectFinalize, origin, types, false)) {
2117                 log.warning(tree.pos(), Warnings.ValueFinalize);
2118             }
2119         }
2120         if (allowRecords && origin.isRecord()) {
2121             // let's find out if this is a user defined accessor in which case the @Override annotation is acceptable
2122             Optional<? extends RecordComponent> recordComponent = origin.getRecordComponents().stream()
2123                     .filter(rc -> rc.accessor == tree.sym && (rc.accessor.flags_field & GENERATED_MEMBER) == 0).findFirst();
2124             if (recordComponent.isPresent()) {
2125                 return;
2126             }
2127         }
2128 
2129         for (Type t = origin.type; t.hasTag(CLASS);
2130              t = types.supertype(t)) {
2131             if (t != origin.type) {
2132                 checkOverride(tree, t, origin, m);
2133             }
2134             for (Type t2 : types.interfaces(t)) {
2135                 checkOverride(tree, t2, origin, m);
2136             }
2137         }
2138 
2139         final boolean explicitOverride = m.attribute(syms.overrideType.tsym) != null;

2535     /** Check that all abstract methods implemented by a class are
2536      *  mutually compatible.
2537      *  @param pos          Position to be used for error reporting.
2538      *  @param c            The class whose interfaces are checked.
2539      */
2540     void checkCompatibleSupertypes(DiagnosticPosition pos, Type c) {
2541         List<Type> supertypes = types.interfaces(c);
2542         Type supertype = types.supertype(c);
2543         if (supertype.hasTag(CLASS) &&
2544             (supertype.tsym.flags() & ABSTRACT) != 0)
2545             supertypes = supertypes.prepend(supertype);
2546         for (List<Type> l = supertypes; l.nonEmpty(); l = l.tail) {
2547             if (!l.head.getTypeArguments().isEmpty() &&
2548                 !checkCompatibleAbstracts(pos, l.head, l.head, c))
2549                 return;
2550             for (List<Type> m = supertypes; m != l; m = m.tail)
2551                 if (!checkCompatibleAbstracts(pos, l.head, m.head, c))
2552                     return;
2553         }
2554         checkCompatibleConcretes(pos, c);
2555 
2556         Type identitySuper = null;
2557         Type superType = types.supertype(c);
2558         if (superType.isIdentityClass())
2559             identitySuper = superType;
2560         if (c.isValueClass() && identitySuper != null && identitySuper.tsym != syms.objectType.tsym) { // Object is special
2561             log.error(pos, Errors.ValueTypeHasIdentitySuperType(c, identitySuper));
2562         }
2563     }
2564 
2565     /** Check that all non-override equivalent methods accessible from 'site'
2566      *  are mutually compatible (JLS 8.4.8/9.4.1).
2567      *
2568      *  @param pos  Position to be used for error reporting.
2569      *  @param site The class whose methods are checked.
2570      *  @param sym  The method symbol to be checked.
2571      */
2572     void checkOverrideClashes(DiagnosticPosition pos, Type site, MethodSymbol sym) {
2573          ClashFilter cf = new ClashFilter(site);
2574         //for each method m1 that is overridden (directly or indirectly)
2575         //by method 'sym' in 'site'...
2576 
2577         ArrayList<Symbol> symbolsByName = new ArrayList<>();
2578         types.membersClosure(site, false).getSymbolsByName(sym.name, cf).forEach(symbolsByName::add);
2579         for (Symbol m1 : symbolsByName) {
2580             if (!sym.overrides(m1, site.tsym, types, false)) {
2581                 continue;
2582             }

4916                 }
4917             } else {
4918                 Assert.error("Unknown pattern: " + currentPattern.getTag());
4919             }
4920             return false;
4921         }
4922 
4923     /** check if a type is a subtype of Externalizable, if that is available. */
4924     boolean isExternalizable(Type t) {
4925         try {
4926             syms.externalizableType.complete();
4927         } catch (CompletionFailure e) {
4928             return false;
4929         }
4930         return types.isSubtype(t, syms.externalizableType);
4931     }
4932 
4933     /**
4934      * Check structure of serialization declarations.
4935      */
4936     public void checkSerialStructure(Env<AttrContext> env, JCClassDecl tree, ClassSymbol c) {
4937         (new SerialTypeVisitor(env)).visit(c, tree);
4938     }
4939 
4940     /**
4941      * This visitor will warn if a serialization-related field or
4942      * method is declared in a suspicious or incorrect way. In
4943      * particular, it will warn for cases where the runtime
4944      * serialization mechanism will silently ignore a mis-declared
4945      * entity.
4946      *
4947      * Distinguished serialization-related fields and methods:
4948      *
4949      * Methods:
4950      *
4951      * private void writeObject(ObjectOutputStream stream) throws IOException
4952      * ANY-ACCESS-MODIFIER Object writeReplace() throws ObjectStreamException
4953      *
4954      * private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException
4955      * private void readObjectNoData() throws ObjectStreamException
4956      * ANY-ACCESS-MODIFIER Object readResolve() throws ObjectStreamException
4957      *
4958      * Fields:
4959      *
4960      * private static final long serialVersionUID
4961      * private static final ObjectStreamField[] serialPersistentFields
4962      *
4963      * Externalizable: methods defined on the interface
4964      * public void writeExternal(ObjectOutput) throws IOException
4965      * public void readExternal(ObjectInput) throws IOException
4966      */
4967     private class SerialTypeVisitor extends ElementKindVisitor14<Void, JCClassDecl> {
4968         Env<AttrContext> env;
4969         SerialTypeVisitor(Env<AttrContext> env) {
4970             this.lint = Check.this.lint;
4971             this.env = env;
4972         }
4973 
4974         private static final Set<String> serialMethodNames =
4975             Set.of("writeObject", "writeReplace",
4976                    "readObject",  "readObjectNoData",
4977                    "readResolve");
4978 
4979         private static final Set<String> serialFieldNames =
4980             Set.of("serialVersionUID", "serialPersistentFields");
4981 
4982         // Type of serialPersistentFields
4983         private final Type OSF_TYPE = new Type.ArrayType(syms.objectStreamFieldType, syms.arrayClass);
4984 
4985         Lint lint;
4986 
4987         @Override
4988         public Void defaultAction(Element e, JCClassDecl p) {
4989             throw new IllegalArgumentException(Objects.requireNonNullElse(e.toString(), ""));
4990         }
4991 
4992         @Override
4993         public Void visitType(TypeElement e, JCClassDecl p) {
4994             runUnderLint(e, p, (symbol, param) -> super.visitType(symbol, param));
4995             return null;
4996         }
4997 
4998         @Override
4999         public Void visitTypeAsClass(TypeElement e,
5000                                      JCClassDecl p) {
5001             // Anonymous classes filtered out by caller.
5002 
5003             ClassSymbol c = (ClassSymbol)e;
5004 
5005             checkCtorAccess(p, c);
5006 
5007             /* Check for missing serialVersionUID; check *not* done
5008              * for enums or records.
5009              * Migrated value classes, need the value class and its corresponding
5010              * identity class to have the same SVUID.
5011              */
5012             VarSymbol svuidSym = null;
5013             for (Symbol sym : c.members().getSymbolsByName(names.serialVersionUID)) {
5014                 if (sym.kind == VAR) {
5015                     svuidSym = (VarSymbol)sym;
5016                     break;
5017                 }
5018             }
5019 
5020             if (svuidSym == null) {
5021                 log.warning(p.pos(), LintWarnings.MissingSVUID(c));
5022             }
5023 
5024             // Check for serialPersistentFields to gate checks for
5025             // non-serializable non-transient instance fields
5026             boolean serialPersistentFieldsPresent =
5027                     c.members()
5028                      .getSymbolsByName(names.serialPersistentFields, sym -> sym.kind == VAR)
5029                      .iterator()
5030                      .hasNext();
5031 
5032             // Check declarations of serialization-related methods and
5033             // fields
5034             final Map<String, Symbol> declaredSerialMethodNames = new HashMap<>();
5035             for(Symbol el : c.getEnclosedElements()) {
5036                 runUnderLint(el, p, (enclosed, tree) -> {
5037                     String name = null;
5038                     switch(enclosed.getKind()) {
5039                     case FIELD -> {
5040                         if (!serialPersistentFieldsPresent) {
5041                             var flags = enclosed.flags();
5042                             if ( ((flags & TRANSIENT) == 0) &&
5043                                  ((flags & STATIC) == 0)) {
5044                                 Type varType = enclosed.asType();
5045                                 if (!canBeSerialized(varType)) {
5046                                     // Note per JLS arrays are
5047                                     // serializable even if the
5048                                     // component type is not.
5049                                     log.warning(
5050                                             TreeInfo.diagnosticPositionFor(enclosed, tree),
5051                                                 LintWarnings.NonSerializableInstanceField);
5052                                 } else if (varType.hasTag(ARRAY)) {
5053                                     ArrayType arrayType = (ArrayType)varType;
5054                                     Type elementType = arrayType.elemtype;

5087                     // Class.getDeclaredMethod. This differs from calling
5088                     // Elements.getAllMembers(TypeElement) as the latter
5089                     // will also pull in default methods from
5090                     // superinterfaces. In other words, the runtime checks
5091                     // (which long predate default methods on interfaces)
5092                     // do not admit the possibility of inheriting methods
5093                     // this way, a difference from general inheritance.
5094 
5095                     // The current implementation just checks the enclosed
5096                     // elements and does not directly check the inherited
5097                     // methods. If all the types are being checked this is
5098                     // less of a concern; however, there are cases that
5099                     // could be missed. In particular, readResolve and
5100                     // writeReplace could, in principle, by inherited from
5101                     // a non-serializable superclass and thus not checked
5102                     // even if compiled with a serializable child class.
5103                     case METHOD -> {
5104                         var method = (MethodSymbol)enclosed;
5105                         name = method.getSimpleName().toString();
5106                         if (serialMethodNames.contains(name)) {
5107                             if (switch (name) {
5108                                 case "writeObject"      -> hasAppropriateWriteObject(tree, e, method);
5109                                 case "writeReplace"     -> hasAppropriateWriteReplace(tree, method, true);
5110                                 case "readObject"       -> hasAppropriateReadObject(tree, e, method);
5111                                 case "readObjectNoData" -> hasAppropriateReadObjectNoData(tree, e, method);
5112                                 case "readResolve"      -> hasAppropriateReadResolve(tree, e, method);
5113                                 default ->  throw new AssertionError();
5114                             }) {
5115                                 declaredSerialMethodNames.put(name, el);
5116                             }
5117                         }
5118                     }
5119                     }
5120                 });
5121             }
5122             if (declaredSerialMethodNames.get("writeReplace") == null &&
5123                     (c.isValueClass() || hasAbstractValueSuperClass(c, Set.of(syms.numberType.tsym))) &&
5124                     !c.isAbstract() && !c.isRecord() &&
5125                     types.unboxedType(c.type) == Type.noType) {
5126                 /* if we are dealing with a value class or with a class with a super class that happens to
5127                  * be an abstract value class, that is not declaring a proper `writeReplace` method, then we
5128                  * need to make sure then that it is inheriting an appropriate one.
5129                  */
5130                 MethodSymbol ms = null;
5131                 Log.DiagnosticHandler discardHandler = log.new DiscardDiagnosticHandler();
5132                 try {
5133                     ms = rs.resolveInternalMethod(env.tree, env, c.type, names.writeReplace, List.nil(), List.nil());
5134                 } catch (FatalError fe) {
5135                     // ignore no method was found
5136                 } finally {
5137                     log.popDiagnosticHandler(discardHandler);
5138                 }
5139                 if (ms == null || !hasAppropriateWriteReplace(p, ms, false)) {
5140                     log.warning(p.pos(),
5141                             c.isValueClass() ? LintWarnings.SerializableValueClassWithoutWriteReplace1 :
5142                                     LintWarnings.SerializableValueClassWithoutWriteReplace2);
5143                 }
5144             }
5145             if (c.isValueClass()) {
5146                 /* Value classes are Serializable through the use of the serialization proxy pattern.
5147                  * The serialization protocol does not support a standard serialized form for value classes.
5148                  * The value class delegates to a serialization proxy by supplying an alternate
5149                  * record or object to be serialized instead of the value class.
5150                  * When the proxy is deserialized it re-constructs the value object and returns the value object.
5151                  *
5152                  * In particular methods:
5153                  *  - writeObject
5154                  *  - readObject and
5155                  *  - readObjectNoData
5156                  * are not invoked for value classes, we need to warn the user about this
5157                  */
5158                 for (Map.Entry<String, Symbol> entry : declaredSerialMethodNames.entrySet()) {
5159                     String key = entry.getKey();
5160                     if (key.equals("writeObject") || key.equals("readObject") || key.equals("readObjectNoData")) {
5161                         log.warning(TreeInfo.diagnosticPositionFor(entry.getValue(), p), LintWarnings.IneffectualSerialMethodValueClass(key));
5162                     }
5163                 }
5164             }
5165             return null;
5166         }
5167 
5168         boolean canBeSerialized(Type type) {
5169             return type.isPrimitive() || rs.isSerializable(type);
5170         }
5171 
5172         private boolean hasAbstractValueSuperClass(Symbol c, Set<Symbol> excluding) {
5173             while (c.getKind() == ElementKind.CLASS) {
5174                 Type sup = ((ClassSymbol)c).getSuperclass();
5175                 if (!sup.hasTag(CLASS) || sup.isErroneous() ||
5176                         sup.tsym == syms.objectType.tsym) {
5177                     return false;
5178                 }
5179                 // if it is a value super class it has to be abstract
5180                 if (sup.isValueClass() && !excluding.contains(sup.tsym)) {
5181                     return true;
5182                 }
5183                 c = sup.tsym;
5184             }
5185             return false;
5186         }
5187 
5188         /**
5189          * Check that Externalizable class needs a public no-arg
5190          * constructor.
5191          *
5192          * Check that a Serializable class has access to the no-arg
5193          * constructor of its first nonserializable superclass.
5194          */
5195         private void checkCtorAccess(JCClassDecl tree, ClassSymbol c) {
5196             if (isExternalizable(c.type)) {
5197                 for(var sym : c.getEnclosedElements()) {
5198                     if (sym.isConstructor() &&
5199                         ((sym.flags() & PUBLIC) == PUBLIC)) {
5200                         if (((MethodSymbol)sym).getParameters().isEmpty()) {
5201                             return;
5202                         }
5203                     }
5204                 }
5205                 log.warning(tree.pos(),
5206                             LintWarnings.ExternalizableMissingPublicNoArgCtor);
5207             } else {

5284 
5285             if (isExternalizable((Type)(e.asType()))) {
5286                 log.warning(
5287                         TreeInfo.diagnosticPositionFor(spf, tree),
5288                             LintWarnings.IneffectualSerialFieldExternalizable);
5289             }
5290 
5291             // Warn if serialPersistentFields is initialized to a
5292             // literal null.
5293             JCTree spfDecl = TreeInfo.declarationFor(spf, tree);
5294             if (spfDecl != null && spfDecl.getTag() == VARDEF) {
5295                 JCVariableDecl variableDef = (JCVariableDecl) spfDecl;
5296                 JCExpression initExpr = variableDef.init;
5297                  if (initExpr != null && TreeInfo.isNull(initExpr)) {
5298                      log.warning(initExpr.pos(),
5299                                  LintWarnings.SPFNullInit);
5300                  }
5301             }
5302         }
5303 
5304         private boolean hasAppropriateWriteObject(JCClassDecl tree, Element e, MethodSymbol method) {
5305             // The "synchronized" modifier is seen in the wild on
5306             // readObject and writeObject methods and is generally
5307             // innocuous.
5308 
5309             // private void writeObject(ObjectOutputStream stream) throws IOException
5310             return isPrivateNonStaticMethod(tree, method) &  // no short-circuit we need to log warnings
5311                     isExpectedReturnType(tree, method, syms.voidType, true) &
5312                     hasExpectedArg(tree, method, syms.objectOutputStreamType) &
5313                     hasExpectedExceptions(tree, method, true, syms.ioExceptionType) &
5314                     checkExternalizable(tree, e, method);
5315         }
5316 
5317         private boolean hasAppropriateWriteReplace(JCClassDecl tree, MethodSymbol method, boolean warn) {
5318             // ANY-ACCESS-MODIFIER Object writeReplace() throws
5319             // ObjectStreamException
5320 
5321             // Excluding abstract, could have a more complicated
5322             // rule based on abstract-ness of the class
5323             return isConcreteInstanceMethod(tree, method, warn) &  // no short-circuit we need to log warnings
5324                     isExpectedReturnType(tree, method, syms.objectType, warn) &
5325                     hasNoArgs(tree, method, warn) &
5326                     hasExpectedExceptions(tree, method, warn, syms.objectStreamExceptionType);
5327         }
5328 
5329         private boolean hasAppropriateReadObject(JCClassDecl tree, Element e, MethodSymbol method) {
5330             // The "synchronized" modifier is seen in the wild on
5331             // readObject and writeObject methods and is generally
5332             // innocuous.
5333 
5334             // private void readObject(ObjectInputStream stream)
5335             //   throws IOException, ClassNotFoundException
5336             return isPrivateNonStaticMethod(tree, method) & // no short-circuit we need to log warnings
5337                     isExpectedReturnType(tree, method, syms.voidType, true) &
5338                     hasExpectedArg(tree, method, syms.objectInputStreamType) &
5339                     hasExpectedExceptions(tree, method, true, syms.ioExceptionType, syms.classNotFoundExceptionType) &
5340                     checkExternalizable(tree, e, method);
5341         }
5342 
5343         private boolean hasAppropriateReadObjectNoData(JCClassDecl tree, Element e, MethodSymbol method) {
5344             // private void readObjectNoData() throws ObjectStreamException
5345             return isPrivateNonStaticMethod(tree, method) & // no short-circuit we need to log warnings
5346                     isExpectedReturnType(tree, method, syms.voidType, true) &
5347                     hasNoArgs(tree, method, true) &
5348                     hasExpectedExceptions(tree, method, true, syms.objectStreamExceptionType) &
5349                     checkExternalizable(tree, e, method);
5350         }
5351 
5352         private boolean hasAppropriateReadResolve(JCClassDecl tree, Element e, MethodSymbol method) {
5353             // ANY-ACCESS-MODIFIER Object readResolve()
5354             // throws ObjectStreamException
5355 
5356             // Excluding abstract, could have a more complicated
5357             // rule based on abstract-ness of the class
5358             return isConcreteInstanceMethod(tree, method, true) & // no short-circuit we need to log warnings
5359                     isExpectedReturnType(tree, method, syms.objectType, true) &
5360                     hasNoArgs(tree, method, true) &
5361                     hasExpectedExceptions(tree, method, true, syms.objectStreamExceptionType);
5362         }
5363 
5364         private void checkWriteExternalRecord(JCClassDecl tree, Element e, MethodSymbol method, boolean isExtern) {
5365             //public void writeExternal(ObjectOutput) throws IOException
5366             checkExternMethodRecord(tree, e, method, syms.objectOutputType, isExtern);
5367         }
5368 
5369         private void checkReadExternalRecord(JCClassDecl tree, Element e, MethodSymbol method, boolean isExtern) {
5370             // public void readExternal(ObjectInput) throws IOException
5371             checkExternMethodRecord(tree, e, method, syms.objectInputType, isExtern);
5372          }
5373 
5374         private void checkExternMethodRecord(JCClassDecl tree, Element e, MethodSymbol method, Type argType,
5375                                              boolean isExtern) {
5376             if (isExtern && isExternMethod(tree, e, method, argType)) {
5377                 log.warning(
5378                         TreeInfo.diagnosticPositionFor(method, tree),
5379                             LintWarnings.IneffectualExternalizableMethodRecord(method.getSimpleName().toString()));
5380             }
5381         }
5382 
5383         boolean isPrivateNonStaticMethod(JCClassDecl tree, MethodSymbol method) {
5384             var flags = method.flags();
5385             boolean result = true;
5386             if ((flags & PRIVATE) == 0) {
5387                 log.warning(
5388                         TreeInfo.diagnosticPositionFor(method, tree),
5389                             LintWarnings.SerialMethodNotPrivate(method.getSimpleName()));
5390                 result = false;
5391             }
5392 
5393             if ((flags & STATIC) != 0) {
5394                 log.warning(
5395                         TreeInfo.diagnosticPositionFor(method, tree),
5396                             LintWarnings.SerialMethodStatic(method.getSimpleName()));
5397                 result = false;
5398             }
5399             return result;
5400         }
5401 
5402         /**
5403          * Per section 1.12 "Serialization of Enum Constants" of
5404          * the serialization specification, due to the special
5405          * serialization handling of enums, any writeObject,
5406          * readObject, writeReplace, and readResolve methods are
5407          * ignored as are serialPersistentFields and
5408          * serialVersionUID fields.
5409          */
5410         @Override
5411         public Void visitTypeAsEnum(TypeElement e,
5412                                     JCClassDecl p) {
5413             boolean isExtern = isExternalizable((Type)e.asType());
5414             for(Element el : e.getEnclosedElements()) {
5415                 runUnderLint(el, p, (enclosed, tree) -> {
5416                     String name = enclosed.getSimpleName().toString();
5417                     switch(enclosed.getKind()) {
5418                     case FIELD -> {
5419                         var field = (VarSymbol)enclosed;

5595                     case FIELD -> {
5596                         var field = (VarSymbol)enclosed;
5597                         switch(name) {
5598                         case "serialPersistentFields" -> {
5599                             log.warning(
5600                                     TreeInfo.diagnosticPositionFor(field, tree),
5601                                         LintWarnings.IneffectualSerialFieldRecord);
5602                         }
5603 
5604                         case "serialVersionUID" -> {
5605                             // Could generate additional warning that
5606                             // svuid value is not checked to match for
5607                             // records.
5608                             checkSerialVersionUID(tree, e, field);
5609                         }}
5610                     }
5611 
5612                     case METHOD -> {
5613                         var method = (MethodSymbol)enclosed;
5614                         switch(name) {
5615                         case "writeReplace" -> hasAppropriateWriteReplace(tree, method, true);
5616                         case "readResolve"  -> hasAppropriateReadResolve(tree, e, method);
5617 
5618                         case "writeExternal" -> checkWriteExternalRecord(tree, e, method, isExtern);
5619                         case "readExternal"  -> checkReadExternalRecord(tree, e, method, isExtern);
5620 
5621                         default -> {
5622                             if (serialMethodNames.contains(name)) {
5623                                 log.warning(
5624                                         TreeInfo.diagnosticPositionFor(method, tree),
5625                                             LintWarnings.IneffectualSerialMethodRecord(name));
5626                             }
5627                         }}
5628                     }}});
5629             }
5630             return null;
5631         }
5632 
5633         boolean isConcreteInstanceMethod(JCClassDecl tree,
5634                                          MethodSymbol method,
5635                                          boolean warn) {
5636             if ((method.flags() & (STATIC | ABSTRACT)) != 0) {
5637                 if (warn) {
5638                     log.warning(
5639                             TreeInfo.diagnosticPositionFor(method, tree),
5640                                 LintWarnings.SerialConcreteInstanceMethod(method.getSimpleName()));
5641                 }
5642                 return false;
5643             }
5644             return true;
5645         }
5646 
5647         private boolean isExpectedReturnType(JCClassDecl tree,
5648                                           MethodSymbol method,
5649                                           Type expectedReturnType,
5650                                           boolean warn) {
5651             // Note: there may be complications checking writeReplace
5652             // and readResolve since they return Object and could, in
5653             // principle, have covariant overrides and any synthetic
5654             // bridge method would not be represented here for
5655             // checking.
5656             Type rtype = method.getReturnType();
5657             if (!types.isSameType(expectedReturnType, rtype)) {
5658                 if (warn) {
5659                     log.warning(
5660                             TreeInfo.diagnosticPositionFor(method, tree),
5661                             LintWarnings.SerialMethodUnexpectedReturnType(method.getSimpleName(),
5662                                                                       rtype, expectedReturnType));
5663                 }
5664                 return false;
5665             }
5666             return true;
5667         }
5668 
5669         private boolean hasExpectedArg(JCClassDecl tree,
5670                                        MethodSymbol method,
5671                                        Type expectedType) {


5672 
5673             var parameters= method.getParameters();
5674 
5675             if (parameters.size() != 1) {
5676                 log.warning(
5677                         TreeInfo.diagnosticPositionFor(method, tree),
5678                             LintWarnings.SerialMethodOneArg(method.getSimpleName(), parameters.size()));
5679                 return false;
5680             }
5681 
5682             Type parameterType = parameters.get(0).asType();
5683             if (!types.isSameType(parameterType, expectedType)) {
5684                 log.warning(
5685                         TreeInfo.diagnosticPositionFor(method, tree),
5686                             LintWarnings.SerialMethodParameterType(method.getSimpleName(),
5687                                                                expectedType,
5688                                                                parameterType));
5689                 return false;
5690             }
5691             return true;
5692         }
5693 
5694         private boolean hasExactlyOneArgWithType(JCClassDecl tree,
5695                                                  Element enclosing,
5696                                                  MethodSymbol method,
5697                                                  Type expectedType) {
5698             var parameters = method.getParameters();
5699             return (parameters.size() == 1) &&
5700                 types.isSameType(parameters.get(0).asType(), expectedType);
5701         }
5702 
5703 
5704         boolean hasNoArgs(JCClassDecl tree, MethodSymbol method, boolean warn) {
5705             var parameters = method.getParameters();
5706             if (!parameters.isEmpty()) {
5707                 if (warn) {
5708                     log.warning(
5709                             TreeInfo.diagnosticPositionFor(parameters.get(0), tree),
5710                             LintWarnings.SerialMethodNoArgs(method.getSimpleName()));
5711                 }
5712                 return false;
5713             }
5714             return true;
5715         }
5716 
5717         private boolean checkExternalizable(JCClassDecl tree, Element enclosing, MethodSymbol method) {
5718             // If the enclosing class is externalizable, warn for the method
5719             if (isExternalizable((Type)enclosing.asType())) {
5720                 log.warning(
5721                         TreeInfo.diagnosticPositionFor(method, tree),
5722                             LintWarnings.IneffectualSerialMethodExternalizable(method.getSimpleName()));
5723                 return false;
5724             }
5725             return true;
5726         }
5727 
5728         private boolean hasExpectedExceptions(JCClassDecl tree,
5729                                               MethodSymbol method,
5730                                               boolean warn,
5731                                               Type... declaredExceptions) {
5732             for (Type thrownType: method.getThrownTypes()) {
5733                 // For each exception in the throws clause of the
5734                 // method, if not an Error and not a RuntimeException,
5735                 // check if the exception is a subtype of a declared
5736                 // exception from the throws clause of the
5737                 // serialization method in question.
5738                 if (types.isSubtype(thrownType, syms.runtimeExceptionType) ||
5739                     types.isSubtype(thrownType, syms.errorType) ) {
5740                     continue;
5741                 } else {
5742                     boolean declared = false;
5743                     for (Type declaredException : declaredExceptions) {
5744                         if (types.isSubtype(thrownType, declaredException)) {
5745                             declared = true;
5746                             continue;
5747                         }
5748                     }
5749                     if (!declared) {
5750                         if (warn) {
5751                             log.warning(
5752                                     TreeInfo.diagnosticPositionFor(method, tree),
5753                                     LintWarnings.SerialMethodUnexpectedException(method.getSimpleName(),
5754                                                                              thrownType));
5755                         }
5756                         return false;
5757                     }
5758                 }
5759             }
5760             return true;
5761         }
5762 
5763         private <E extends Element> Void runUnderLint(E symbol, JCClassDecl p, BiConsumer<E, JCClassDecl> task) {
5764             Lint prevLint = lint;
5765             try {
5766                 lint = lint.augment((Symbol) symbol);
5767 
5768                 if (lint.isEnabled(LintCategory.SERIAL)) {
5769                     task.accept(symbol, p);
5770                 }
5771 
5772                 return null;
5773             } finally {
5774                 lint = prevLint;
5775             }
5776         }
5777 
5778     }
5779 
5780     void checkRequiresIdentity(JCTree tree, Lint lint) {
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