1 /*
   2  * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.tools.javac.comp;
  27 
  28 import java.util.*;
  29 import java.util.Set;
  30 
  31 import com.sun.tools.javac.code.*;
  32 import com.sun.tools.javac.jvm.*;
  33 import com.sun.tools.javac.tree.*;
  34 import com.sun.tools.javac.util.*;
  35 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
  36 import com.sun.tools.javac.util.List;
  37 
  38 import com.sun.tools.javac.tree.JCTree.*;
  39 import com.sun.tools.javac.code.Lint;
  40 import com.sun.tools.javac.code.Lint.LintCategory;
  41 import com.sun.tools.javac.code.Type.*;
  42 import com.sun.tools.javac.code.Symbol.*;
  43 
  44 import static com.sun.tools.javac.code.Flags.*;
  45 import static com.sun.tools.javac.code.Kinds.*;
  46 import static com.sun.tools.javac.code.TypeTags.*;
  47 
  48 import static com.sun.tools.javac.main.OptionName.*;
  49 
  50 /** Type checking helper class for the attribution phase.
  51  *
  52  *  <p><b>This is NOT part of any supported API.
  53  *  If you write code that depends on this, you do so at your own risk.
  54  *  This code and its internal interfaces are subject to change or
  55  *  deletion without notice.</b>
  56  */
  57 public class Check {
  58     protected static final Context.Key<Check> checkKey =
  59         new Context.Key<Check>();
  60 
  61     private final Names names;
  62     private final Log log;
  63     private final Symtab syms;
  64     private final Enter enter;
  65     private final Infer infer;
  66     private final Types types;
  67     private final JCDiagnostic.Factory diags;
  68     private final boolean skipAnnotations;
  69     private boolean warnOnSyntheticConflicts;
  70     private boolean suppressAbortOnBadClassFile;
  71     private boolean enableSunApiLintControl;
  72     private final TreeInfo treeinfo;
  73 
  74     // The set of lint options currently in effect. It is initialized
  75     // from the context, and then is set/reset as needed by Attr as it
  76     // visits all the various parts of the trees during attribution.
  77     private Lint lint;
  78 
  79     // The method being analyzed in Attr - it is set/reset as needed by
  80     // Attr as it visits new method declarations.
  81     private MethodSymbol method;
  82 
  83     public static Check instance(Context context) {
  84         Check instance = context.get(checkKey);
  85         if (instance == null)
  86             instance = new Check(context);
  87         return instance;
  88     }
  89 
  90     protected Check(Context context) {
  91         context.put(checkKey, this);
  92 
  93         names = Names.instance(context);
  94         log = Log.instance(context);
  95         syms = Symtab.instance(context);
  96         enter = Enter.instance(context);
  97         infer = Infer.instance(context);
  98         this.types = Types.instance(context);
  99         diags = JCDiagnostic.Factory.instance(context);
 100         Options options = Options.instance(context);
 101         lint = Lint.instance(context);
 102         treeinfo = TreeInfo.instance(context);
 103 
 104         Source source = Source.instance(context);
 105         allowGenerics = source.allowGenerics();
 106         allowAnnotations = source.allowAnnotations();
 107         allowCovariantReturns = source.allowCovariantReturns();
 108         allowSimplifiedVarargs = source.allowSimplifiedVarargs();
 109         complexInference = options.isSet(COMPLEXINFERENCE);
 110         skipAnnotations = options.isSet("skipAnnotations");
 111         warnOnSyntheticConflicts = options.isSet("warnOnSyntheticConflicts");
 112         suppressAbortOnBadClassFile = options.isSet("suppressAbortOnBadClassFile");
 113         enableSunApiLintControl = options.isSet("enableSunApiLintControl");
 114 
 115         Target target = Target.instance(context);
 116         syntheticNameChar = target.syntheticNameChar();
 117 
 118         boolean verboseDeprecated = lint.isEnabled(LintCategory.DEPRECATION);
 119         boolean verboseUnchecked = lint.isEnabled(LintCategory.UNCHECKED);
 120         boolean verboseSunApi = lint.isEnabled(LintCategory.SUNAPI);
 121         boolean enforceMandatoryWarnings = source.enforceMandatoryWarnings();
 122 
 123         deprecationHandler = new MandatoryWarningHandler(log, verboseDeprecated,
 124                 enforceMandatoryWarnings, "deprecated", LintCategory.DEPRECATION);
 125         uncheckedHandler = new MandatoryWarningHandler(log, verboseUnchecked,
 126                 enforceMandatoryWarnings, "unchecked", LintCategory.UNCHECKED);
 127         sunApiHandler = new MandatoryWarningHandler(log, verboseSunApi,
 128                 enforceMandatoryWarnings, "sunapi", null);
 129 
 130         deferredLintHandler = DeferredLintHandler.immediateHandler;
 131     }
 132 
 133     /** Switch: generics enabled?
 134      */
 135     boolean allowGenerics;
 136 
 137     /** Switch: annotations enabled?
 138      */
 139     boolean allowAnnotations;
 140 
 141     /** Switch: covariant returns enabled?
 142      */
 143     boolean allowCovariantReturns;
 144 
 145     /** Switch: simplified varargs enabled?
 146      */
 147     boolean allowSimplifiedVarargs;
 148 
 149     /** Switch: -complexinference option set?
 150      */
 151     boolean complexInference;
 152 
 153     /** Character for synthetic names
 154      */
 155     char syntheticNameChar;
 156 
 157     /** A table mapping flat names of all compiled classes in this run to their
 158      *  symbols; maintained from outside.
 159      */
 160     public Map<Name,ClassSymbol> compiled = new HashMap<Name, ClassSymbol>();
 161 
 162     /** A handler for messages about deprecated usage.
 163      */
 164     private MandatoryWarningHandler deprecationHandler;
 165 
 166     /** A handler for messages about unchecked or unsafe usage.
 167      */
 168     private MandatoryWarningHandler uncheckedHandler;
 169 
 170     /** A handler for messages about using proprietary API.
 171      */
 172     private MandatoryWarningHandler sunApiHandler;
 173 
 174     /** A handler for deferred lint warnings.
 175      */
 176     private DeferredLintHandler deferredLintHandler;
 177 
 178 /* *************************************************************************
 179  * Errors and Warnings
 180  **************************************************************************/
 181 
 182     Lint setLint(Lint newLint) {
 183         Lint prev = lint;
 184         lint = newLint;
 185         return prev;
 186     }
 187 
 188     DeferredLintHandler setDeferredLintHandler(DeferredLintHandler newDeferredLintHandler) {
 189         DeferredLintHandler prev = deferredLintHandler;
 190         deferredLintHandler = newDeferredLintHandler;
 191         return prev;
 192     }
 193 
 194     MethodSymbol setMethod(MethodSymbol newMethod) {
 195         MethodSymbol prev = method;
 196         method = newMethod;
 197         return prev;
 198     }
 199 
 200     /** Warn about deprecated symbol.
 201      *  @param pos        Position to be used for error reporting.
 202      *  @param sym        The deprecated symbol.
 203      */
 204     void warnDeprecated(DiagnosticPosition pos, Symbol sym) {
 205         if (!lint.isSuppressed(LintCategory.DEPRECATION))
 206             deprecationHandler.report(pos, "has.been.deprecated", sym, sym.location());
 207     }
 208 
 209     /** Warn about unchecked operation.
 210      *  @param pos        Position to be used for error reporting.
 211      *  @param msg        A string describing the problem.
 212      */
 213     public void warnUnchecked(DiagnosticPosition pos, String msg, Object... args) {
 214         if (!lint.isSuppressed(LintCategory.UNCHECKED))
 215             uncheckedHandler.report(pos, msg, args);
 216     }
 217 
 218     /** Warn about unsafe vararg method decl.
 219      *  @param pos        Position to be used for error reporting.
 220      *  @param sym        The deprecated symbol.
 221      */
 222     void warnUnsafeVararg(DiagnosticPosition pos, String key, Object... args) {
 223         if (lint.isEnabled(LintCategory.VARARGS) && allowSimplifiedVarargs)
 224             log.warning(LintCategory.VARARGS, pos, key, args);
 225     }
 226 
 227     /** Warn about using proprietary API.
 228      *  @param pos        Position to be used for error reporting.
 229      *  @param msg        A string describing the problem.
 230      */
 231     public void warnSunApi(DiagnosticPosition pos, String msg, Object... args) {
 232         if (!lint.isSuppressed(LintCategory.SUNAPI))
 233             sunApiHandler.report(pos, msg, args);
 234     }
 235 
 236     public void warnStatic(DiagnosticPosition pos, String msg, Object... args) {
 237         if (lint.isEnabled(LintCategory.STATIC))
 238             log.warning(LintCategory.STATIC, pos, msg, args);
 239     }
 240 
 241     /**
 242      * Report any deferred diagnostics.
 243      */
 244     public void reportDeferredDiagnostics() {
 245         deprecationHandler.reportDeferredDiagnostic();
 246         uncheckedHandler.reportDeferredDiagnostic();
 247         sunApiHandler.reportDeferredDiagnostic();
 248     }
 249 
 250 
 251     /** Report a failure to complete a class.
 252      *  @param pos        Position to be used for error reporting.
 253      *  @param ex         The failure to report.
 254      */
 255     public Type completionError(DiagnosticPosition pos, CompletionFailure ex) {
 256         log.error(pos, "cant.access", ex.sym, ex.getDetailValue());
 257         if (ex instanceof ClassReader.BadClassFile
 258                 && !suppressAbortOnBadClassFile) throw new Abort();
 259         else return syms.errType;
 260     }
 261 
 262     /** Report a type error.
 263      *  @param pos        Position to be used for error reporting.
 264      *  @param problem    A string describing the error.
 265      *  @param found      The type that was found.
 266      *  @param req        The type that was required.
 267      */
 268     Type typeError(DiagnosticPosition pos, Object problem, Type found, Type req) {
 269         log.error(pos, "prob.found.req",
 270                   problem, found, req);
 271         return types.createErrorType(found);
 272     }
 273 
 274     Type typeError(DiagnosticPosition pos, String problem, Type found, Type req, Object explanation) {
 275         log.error(pos, "prob.found.req.1", problem, found, req, explanation);
 276         return types.createErrorType(found);
 277     }
 278 
 279     /** Report an error that wrong type tag was found.
 280      *  @param pos        Position to be used for error reporting.
 281      *  @param required   An internationalized string describing the type tag
 282      *                    required.
 283      *  @param found      The type that was found.
 284      */
 285     Type typeTagError(DiagnosticPosition pos, Object required, Object found) {
 286         // this error used to be raised by the parser,
 287         // but has been delayed to this point:
 288         if (found instanceof Type && ((Type)found).tag == VOID) {
 289             log.error(pos, "illegal.start.of.type");
 290             return syms.errType;
 291         }
 292         log.error(pos, "type.found.req", found, required);
 293         return types.createErrorType(found instanceof Type ? (Type)found : syms.errType);
 294     }
 295 
 296     /** Report an error that symbol cannot be referenced before super
 297      *  has been called.
 298      *  @param pos        Position to be used for error reporting.
 299      *  @param sym        The referenced symbol.
 300      */
 301     void earlyRefError(DiagnosticPosition pos, Symbol sym) {
 302         log.error(pos, "cant.ref.before.ctor.called", sym);
 303     }
 304 
 305     /** Report duplicate declaration error.
 306      */
 307     void duplicateError(DiagnosticPosition pos, Symbol sym) {
 308         if (!sym.type.isErroneous()) {
 309             Symbol location = sym.location();
 310             if (location.kind == MTH &&
 311                     ((MethodSymbol)location).isStaticOrInstanceInit()) {
 312                 log.error(pos, "already.defined.in.clinit", kindName(sym), sym,
 313                         kindName(sym.location()), kindName(sym.location().enclClass()),
 314                         sym.location().enclClass());
 315             } else {
 316                 log.error(pos, "already.defined", kindName(sym), sym,
 317                         kindName(sym.location()), sym.location());
 318             }
 319         }
 320     }
 321 
 322     /** Report array/varargs duplicate declaration
 323      */
 324     void varargsDuplicateError(DiagnosticPosition pos, Symbol sym1, Symbol sym2) {
 325         if (!sym1.type.isErroneous() && !sym2.type.isErroneous()) {
 326             log.error(pos, "array.and.varargs", sym1, sym2, sym2.location());
 327         }
 328     }
 329 
 330 /* ************************************************************************
 331  * duplicate declaration checking
 332  *************************************************************************/
 333 
 334     /** Check that variable does not hide variable with same name in
 335      *  immediately enclosing local scope.
 336      *  @param pos           Position for error reporting.
 337      *  @param v             The symbol.
 338      *  @param s             The scope.
 339      */
 340     void checkTransparentVar(DiagnosticPosition pos, VarSymbol v, Scope s) {
 341         if (s.next != null) {
 342             for (Scope.Entry e = s.next.lookup(v.name);
 343                  e.scope != null && e.sym.owner == v.owner;
 344                  e = e.next()) {
 345                 if (e.sym.kind == VAR &&
 346                     (e.sym.owner.kind & (VAR | MTH)) != 0 &&
 347                     v.name != names.error) {
 348                     duplicateError(pos, e.sym);
 349                     return;
 350                 }
 351             }
 352         }
 353     }
 354 
 355     /** Check that a class or interface does not hide a class or
 356      *  interface with same name in immediately enclosing local scope.
 357      *  @param pos           Position for error reporting.
 358      *  @param c             The symbol.
 359      *  @param s             The scope.
 360      */
 361     void checkTransparentClass(DiagnosticPosition pos, ClassSymbol c, Scope s) {
 362         if (s.next != null) {
 363             for (Scope.Entry e = s.next.lookup(c.name);
 364                  e.scope != null && e.sym.owner == c.owner;
 365                  e = e.next()) {
 366                 if (e.sym.kind == TYP && e.sym.type.tag != TYPEVAR &&
 367                     (e.sym.owner.kind & (VAR | MTH)) != 0 &&
 368                     c.name != names.error) {
 369                     duplicateError(pos, e.sym);
 370                     return;
 371                 }
 372             }
 373         }
 374     }
 375 
 376     /** Check that class does not have the same name as one of
 377      *  its enclosing classes, or as a class defined in its enclosing scope.
 378      *  return true if class is unique in its enclosing scope.
 379      *  @param pos           Position for error reporting.
 380      *  @param name          The class name.
 381      *  @param s             The enclosing scope.
 382      */
 383     boolean checkUniqueClassName(DiagnosticPosition pos, Name name, Scope s) {
 384         for (Scope.Entry e = s.lookup(name); e.scope == s; e = e.next()) {
 385             if (e.sym.kind == TYP && e.sym.name != names.error) {
 386                 duplicateError(pos, e.sym);
 387                 return false;
 388             }
 389         }
 390         for (Symbol sym = s.owner; sym != null; sym = sym.owner) {
 391             if (sym.kind == TYP && sym.name == name && sym.name != names.error) {
 392                 duplicateError(pos, sym);
 393                 return true;
 394             }
 395         }
 396         return true;
 397     }
 398 
 399 /* *************************************************************************
 400  * Class name generation
 401  **************************************************************************/
 402 
 403     /** Return name of local class.
 404      *  This is of the form    <enclClass> $ n <classname>
 405      *  where
 406      *    enclClass is the flat name of the enclosing class,
 407      *    classname is the simple name of the local class
 408      */
 409     Name localClassName(ClassSymbol c) {
 410         for (int i=1; ; i++) {
 411             Name flatname = names.
 412                 fromString("" + c.owner.enclClass().flatname +
 413                            syntheticNameChar + i +
 414                            c.name);
 415             if (compiled.get(flatname) == null) return flatname;
 416         }
 417     }
 418 
 419 /* *************************************************************************
 420  * Type Checking
 421  **************************************************************************/
 422 
 423     /** Check that a given type is assignable to a given proto-type.
 424      *  If it is, return the type, otherwise return errType.
 425      *  @param pos        Position to be used for error reporting.
 426      *  @param found      The type that was found.
 427      *  @param req        The type that was required.
 428      */
 429     Type checkType(DiagnosticPosition pos, Type found, Type req) {
 430         return checkType(pos, found, req, "incompatible.types");
 431     }
 432 
 433     Type checkType(DiagnosticPosition pos, Type found, Type req, String errKey) {
 434         if (req.tag == ERROR)
 435             return req;
 436         if (found.tag == FORALL)
 437             return instantiatePoly(pos, (ForAll)found, req, convertWarner(pos, found, req));
 438         if (req.tag == NONE)
 439             return found;
 440         if (types.isAssignable(found, req, convertWarner(pos, found, req)))
 441             return found;
 442         if (found.tag <= DOUBLE && req.tag <= DOUBLE)
 443             return typeError(pos, diags.fragment("possible.loss.of.precision"), found, req);
 444         if (found.isSuperBound()) {
 445             log.error(pos, "assignment.from.super-bound", found);
 446             return types.createErrorType(found);
 447         }
 448         if (req.isExtendsBound()) {
 449             log.error(pos, "assignment.to.extends-bound", req);
 450             return types.createErrorType(found);
 451         }
 452         return typeError(pos, diags.fragment(errKey), found, req);
 453     }
 454 
 455     /** Instantiate polymorphic type to some prototype, unless
 456      *  prototype is `anyPoly' in which case polymorphic type
 457      *  is returned unchanged.
 458      */
 459     Type instantiatePoly(DiagnosticPosition pos, ForAll t, Type pt, Warner warn) throws Infer.NoInstanceException {
 460         if (pt == Infer.anyPoly && complexInference) {
 461             return t;
 462         } else if (pt == Infer.anyPoly || pt.tag == NONE) {
 463             Type newpt = t.qtype.tag <= VOID ? t.qtype : syms.objectType;
 464             return instantiatePoly(pos, t, newpt, warn);
 465         } else if (pt.tag == ERROR) {
 466             return pt;
 467         } else {
 468             try {
 469                 return infer.instantiateExpr(t, pt, warn);
 470             } catch (Infer.NoInstanceException ex) {
 471                 if (ex.isAmbiguous) {
 472                     JCDiagnostic d = ex.getDiagnostic();
 473                     log.error(pos,
 474                               "undetermined.type" + (d!=null ? ".1" : ""),
 475                               t, d);
 476                     return types.createErrorType(pt);
 477                 } else {
 478                     JCDiagnostic d = ex.getDiagnostic();
 479                     return typeError(pos,
 480                                      diags.fragment("incompatible.types" + (d!=null ? ".1" : ""), d),
 481                                      t, pt);
 482                 }
 483             } catch (Infer.InvalidInstanceException ex) {
 484                 JCDiagnostic d = ex.getDiagnostic();
 485                 log.error(pos, "invalid.inferred.types", t.tvars, d);
 486                 return types.createErrorType(pt);
 487             }
 488         }
 489     }
 490 
 491     /** Check that a given type can be cast to a given target type.
 492      *  Return the result of the cast.
 493      *  @param pos        Position to be used for error reporting.
 494      *  @param found      The type that is being cast.
 495      *  @param req        The target type of the cast.
 496      */
 497     Type checkCastable(DiagnosticPosition pos, Type found, Type req) {
 498         if (found.tag == FORALL) {
 499             instantiatePoly(pos, (ForAll) found, req, castWarner(pos, found, req));
 500             return req;
 501         } else if (types.isCastable(found, req, castWarner(pos, found, req))) {
 502             return req;
 503         } else {
 504             return typeError(pos,
 505                              diags.fragment("inconvertible.types"),
 506                              found, req);
 507         }
 508     }
 509 //where
 510         /** Is type a type variable, or a (possibly multi-dimensional) array of
 511          *  type variables?
 512          */
 513         boolean isTypeVar(Type t) {
 514             return t.tag == TYPEVAR || t.tag == ARRAY && isTypeVar(types.elemtype(t));
 515         }
 516 
 517     /** Check that a type is within some bounds.
 518      *
 519      *  Used in TypeApply to verify that, e.g., X in V<X> is a valid
 520      *  type argument.
 521      *  @param pos           Position to be used for error reporting.
 522      *  @param a             The type that should be bounded by bs.
 523      *  @param bs            The bound.
 524      */
 525     private boolean checkExtends(Type a, TypeVar bs) {
 526          if (a.isUnbound()) {
 527              return true;
 528          } else if (a.tag != WILDCARD) {
 529              a = types.upperBound(a);
 530              return types.isSubtype(a, bs.bound);
 531          } else if (a.isExtendsBound()) {
 532              return types.isCastable(bs.getUpperBound(), types.upperBound(a), Warner.noWarnings);
 533          } else if (a.isSuperBound()) {
 534              return !types.notSoftSubtype(types.lowerBound(a), bs.getUpperBound());
 535          }
 536          return true;
 537      }
 538 
 539     /** Check that type is different from 'void'.
 540      *  @param pos           Position to be used for error reporting.
 541      *  @param t             The type to be checked.
 542      */
 543     Type checkNonVoid(DiagnosticPosition pos, Type t) {
 544         if (t.tag == VOID) {
 545             log.error(pos, "void.not.allowed.here");
 546             return types.createErrorType(t);
 547         } else {
 548             return t;
 549         }
 550     }
 551 
 552     /** Check that type is a class or interface type.
 553      *  @param pos           Position to be used for error reporting.
 554      *  @param t             The type to be checked.
 555      */
 556     Type checkClassType(DiagnosticPosition pos, Type t) {
 557         if (t.tag != CLASS && t.tag != ERROR)
 558             return typeTagError(pos,
 559                                 diags.fragment("type.req.class"),
 560                                 (t.tag == TYPEVAR)
 561                                 ? diags.fragment("type.parameter", t)
 562                                 : t);
 563         else
 564             return t;
 565     }
 566 
 567     /** Check that type is a class or interface type.
 568      *  @param pos           Position to be used for error reporting.
 569      *  @param t             The type to be checked.
 570      *  @param noBounds    True if type bounds are illegal here.
 571      */
 572     Type checkClassType(DiagnosticPosition pos, Type t, boolean noBounds) {
 573         t = checkClassType(pos, t);
 574         if (noBounds && t.isParameterized()) {
 575             List<Type> args = t.getTypeArguments();
 576             while (args.nonEmpty()) {
 577                 if (args.head.tag == WILDCARD)
 578                     return typeTagError(pos,
 579                                         diags.fragment("type.req.exact"),
 580                                         args.head);
 581                 args = args.tail;
 582             }
 583         }
 584         return t;
 585     }
 586 
 587     /** Check that type is a reifiable class, interface or array type.
 588      *  @param pos           Position to be used for error reporting.
 589      *  @param t             The type to be checked.
 590      */
 591     Type checkReifiableReferenceType(DiagnosticPosition pos, Type t) {
 592         if (t.tag != CLASS && t.tag != ARRAY && t.tag != ERROR) {
 593             return typeTagError(pos,
 594                                 diags.fragment("type.req.class.array"),
 595                                 t);
 596         } else if (!types.isReifiable(t)) {
 597             log.error(pos, "illegal.generic.type.for.instof");
 598             return types.createErrorType(t);
 599         } else {
 600             return t;
 601         }
 602     }
 603 
 604     /** Check that type is a reference type, i.e. a class, interface or array type
 605      *  or a type variable.
 606      *  @param pos           Position to be used for error reporting.
 607      *  @param t             The type to be checked.
 608      */
 609     Type checkRefType(DiagnosticPosition pos, Type t) {
 610         switch (t.tag) {
 611         case CLASS:
 612         case ARRAY:
 613         case TYPEVAR:
 614         case WILDCARD:
 615         case ERROR:
 616             return t;
 617         default:
 618             return typeTagError(pos,
 619                                 diags.fragment("type.req.ref"),
 620                                 t);
 621         }
 622     }
 623 
 624     /** Check that each type is a reference type, i.e. a class, interface or array type
 625      *  or a type variable.
 626      *  @param trees         Original trees, used for error reporting.
 627      *  @param types         The types to be checked.
 628      */
 629     List<Type> checkRefTypes(List<JCExpression> trees, List<Type> types) {
 630         List<JCExpression> tl = trees;
 631         for (List<Type> l = types; l.nonEmpty(); l = l.tail) {
 632             l.head = checkRefType(tl.head.pos(), l.head);
 633             tl = tl.tail;
 634         }
 635         return types;
 636     }
 637 
 638     /** Check that type is a null or reference type.
 639      *  @param pos           Position to be used for error reporting.
 640      *  @param t             The type to be checked.
 641      */
 642     Type checkNullOrRefType(DiagnosticPosition pos, Type t) {
 643         switch (t.tag) {
 644         case CLASS:
 645         case ARRAY:
 646         case TYPEVAR:
 647         case WILDCARD:
 648         case BOT:
 649         case ERROR:
 650             return t;
 651         default:
 652             return typeTagError(pos,
 653                                 diags.fragment("type.req.ref"),
 654                                 t);
 655         }
 656     }
 657 
 658     /** Check that flag set does not contain elements of two conflicting sets. s
 659      *  Return true if it doesn't.
 660      *  @param pos           Position to be used for error reporting.
 661      *  @param flags         The set of flags to be checked.
 662      *  @param set1          Conflicting flags set #1.
 663      *  @param set2          Conflicting flags set #2.
 664      */
 665     boolean checkDisjoint(DiagnosticPosition pos, long flags, long set1, long set2) {
 666         if ((flags & set1) != 0 && (flags & set2) != 0) {
 667             log.error(pos,
 668                       "illegal.combination.of.modifiers",
 669                       asFlagSet(TreeInfo.firstFlag(flags & set1)),
 670                       asFlagSet(TreeInfo.firstFlag(flags & set2)));
 671             return false;
 672         } else
 673             return true;
 674     }
 675 
 676     /** Check that usage of diamond operator is correct (i.e. diamond should not
 677      * be used with non-generic classes or in anonymous class creation expressions)
 678      */
 679     Type checkDiamond(JCNewClass tree, Type t) {
 680         if (!TreeInfo.isDiamond(tree) ||
 681                 t.isErroneous()) {
 682             return checkClassType(tree.clazz.pos(), t, true);
 683         } else if (tree.def != null) {
 684             log.error(tree.clazz.pos(),
 685                     "cant.apply.diamond.1",
 686                     t, diags.fragment("diamond.and.anon.class", t));
 687             return types.createErrorType(t);
 688         } else if (t.tsym.type.getTypeArguments().isEmpty()) {
 689             log.error(tree.clazz.pos(),
 690                 "cant.apply.diamond.1",
 691                 t, diags.fragment("diamond.non.generic", t));
 692             return types.createErrorType(t);
 693         } else if (tree.typeargs != null &&
 694                 tree.typeargs.nonEmpty()) {
 695             log.error(tree.clazz.pos(),
 696                 "cant.apply.diamond.1",
 697                 t, diags.fragment("diamond.and.explicit.params", t));
 698             return types.createErrorType(t);
 699         } else {
 700             return t;
 701         }
 702     }
 703 
 704     void checkVarargsMethodDecl(Env<AttrContext> env, JCMethodDecl tree) {
 705         MethodSymbol m = tree.sym;
 706         if (!allowSimplifiedVarargs) return;
 707         boolean hasTrustMeAnno = m.attribute(syms.trustMeType.tsym) != null;
 708         Type varargElemType = null;
 709         if (m.isVarArgs()) {
 710             varargElemType = types.elemtype(tree.params.last().type);
 711         }
 712         if (hasTrustMeAnno && !isTrustMeAllowedOnMethod(m)) {
 713             if (varargElemType != null) {
 714                 log.error(tree,
 715                         "varargs.invalid.trustme.anno",
 716                         syms.trustMeType.tsym,
 717                         diags.fragment("varargs.trustme.on.virtual.varargs", m));
 718             } else {
 719                 log.error(tree,
 720                             "varargs.invalid.trustme.anno",
 721                             syms.trustMeType.tsym,
 722                             diags.fragment("varargs.trustme.on.non.varargs.meth", m));
 723             }
 724         } else if (hasTrustMeAnno && varargElemType != null &&
 725                             types.isReifiable(varargElemType)) {
 726             warnUnsafeVararg(tree,
 727                             "varargs.redundant.trustme.anno",
 728                             syms.trustMeType.tsym,
 729                             diags.fragment("varargs.trustme.on.reifiable.varargs", varargElemType));
 730         }
 731         else if (!hasTrustMeAnno && varargElemType != null &&
 732                 !types.isReifiable(varargElemType)) {
 733             warnUnchecked(tree.params.head.pos(), "unchecked.varargs.non.reifiable.type", varargElemType);
 734         }
 735     }
 736     //where
 737         private boolean isTrustMeAllowedOnMethod(Symbol s) {
 738             return (s.flags() & VARARGS) != 0 &&
 739                 (s.isConstructor() ||
 740                     (s.flags() & (STATIC | FINAL)) != 0);
 741         }
 742 
 743     /**
 744      * Check that vararg method call is sound
 745      * @param pos Position to be used for error reporting.
 746      * @param argtypes Actual arguments supplied to vararg method.
 747      */
 748     void checkVararg(DiagnosticPosition pos, List<Type> argtypes, Symbol msym) {
 749         Type argtype = argtypes.last();
 750         if (!types.isReifiable(argtype) &&
 751                 (!allowSimplifiedVarargs ||
 752                 msym.attribute(syms.trustMeType.tsym) == null ||
 753                 !isTrustMeAllowedOnMethod(msym))) {
 754             warnUnchecked(pos,
 755                               "unchecked.generic.array.creation",
 756                               argtype);
 757         }
 758     }
 759 
 760     /**
 761      * Check that type 't' is a valid instantiation of a generic class
 762      * (see JLS 4.5)
 763      *
 764      * @param t class type to be checked
 765      * @return true if 't' is well-formed
 766      */
 767     public boolean checkValidGenericType(Type t) {
 768         return firstIncompatibleTypeArg(t) == null;
 769     }
 770     //WHERE
 771         private Type firstIncompatibleTypeArg(Type type) {
 772             List<Type> formals = type.tsym.type.allparams();
 773             List<Type> actuals = type.allparams();
 774             List<Type> args = type.getTypeArguments();
 775             List<Type> forms = type.tsym.type.getTypeArguments();
 776             ListBuffer<Type> tvars_buf = new ListBuffer<Type>();
 777 
 778             // For matching pairs of actual argument types `a' and
 779             // formal type parameters with declared bound `b' ...
 780             while (args.nonEmpty() && forms.nonEmpty()) {
 781                 // exact type arguments needs to know their
 782                 // bounds (for upper and lower bound
 783                 // calculations).  So we create new TypeVars with
 784                 // bounds substed with actuals.
 785                 tvars_buf.append(types.substBound(((TypeVar)forms.head),
 786                                                   formals,
 787                                                   actuals));
 788                 args = args.tail;
 789                 forms = forms.tail;
 790             }
 791 
 792             args = type.getTypeArguments();
 793             List<Type> tvars_cap = types.substBounds(formals,
 794                                       formals,
 795                                       types.capture(type).allparams());
 796             while (args.nonEmpty() && tvars_cap.nonEmpty()) {
 797                 // Let the actual arguments know their bound
 798                 args.head.withTypeVar((TypeVar)tvars_cap.head);
 799                 args = args.tail;
 800                 tvars_cap = tvars_cap.tail;
 801             }
 802 
 803             args = type.getTypeArguments();
 804             List<Type> tvars = tvars_buf.toList();
 805 
 806             while (args.nonEmpty() && tvars.nonEmpty()) {
 807                 Type actual = types.subst(args.head,
 808                     type.tsym.type.getTypeArguments(),
 809                     tvars_buf.toList());
 810                 if (!isTypeArgErroneous(actual) &&
 811                         !tvars.head.getUpperBound().isErroneous() &&
 812                         !checkExtends(actual, (TypeVar)tvars.head)) {
 813                     return args.head;
 814                 }
 815                 args = args.tail;
 816                 tvars = tvars.tail;
 817             }
 818 
 819             args = type.getTypeArguments();
 820             tvars = tvars_buf.toList();
 821 
 822             for (Type arg : types.capture(type).getTypeArguments()) {
 823                 if (arg.tag == TYPEVAR &&
 824                         arg.getUpperBound().isErroneous() &&
 825                         !tvars.head.getUpperBound().isErroneous() &&
 826                         !isTypeArgErroneous(args.head)) {
 827                     return args.head;
 828                 }
 829                 tvars = tvars.tail;
 830                 args = args.tail;
 831             }
 832 
 833             return null;
 834         }
 835         //where
 836         boolean isTypeArgErroneous(Type t) {
 837             return isTypeArgErroneous.visit(t);
 838         }
 839 
 840         Types.UnaryVisitor<Boolean> isTypeArgErroneous = new Types.UnaryVisitor<Boolean>() {
 841             public Boolean visitType(Type t, Void s) {
 842                 return t.isErroneous();
 843             }
 844             @Override
 845             public Boolean visitTypeVar(TypeVar t, Void s) {
 846                 return visit(t.getUpperBound());
 847             }
 848             @Override
 849             public Boolean visitCapturedType(CapturedType t, Void s) {
 850                 return visit(t.getUpperBound()) ||
 851                         visit(t.getLowerBound());
 852             }
 853             @Override
 854             public Boolean visitWildcardType(WildcardType t, Void s) {
 855                 return visit(t.type);
 856             }
 857         };
 858 
 859     /** Check that given modifiers are legal for given symbol and
 860      *  return modifiers together with any implicit modififiers for that symbol.
 861      *  Warning: we can't use flags() here since this method
 862      *  is called during class enter, when flags() would cause a premature
 863      *  completion.
 864      *  @param pos           Position to be used for error reporting.
 865      *  @param flags         The set of modifiers given in a definition.
 866      *  @param sym           The defined symbol.
 867      */
 868     long checkFlags(DiagnosticPosition pos, long flags, Symbol sym, JCTree tree) {
 869         long mask;
 870         long implicit = 0;
 871         switch (sym.kind) {
 872         case VAR:
 873             if (sym.owner.kind != TYP)
 874                 mask = LocalVarFlags;
 875             else if ((sym.owner.flags_field & INTERFACE) != 0)
 876                 mask = implicit = InterfaceVarFlags;
 877             else
 878                 mask = VarFlags;
 879             break;
 880         case MTH:
 881             if (sym.name == names.init) {
 882                 if ((sym.owner.flags_field & ENUM) != 0) {
 883                     // enum constructors cannot be declared public or
 884                     // protected and must be implicitly or explicitly
 885                     // private
 886                     implicit = PRIVATE;
 887                     mask = PRIVATE;
 888                 } else
 889                     mask = ConstructorFlags;
 890             }  else if ((sym.owner.flags_field & INTERFACE) != 0)
 891                 mask = implicit = InterfaceMethodFlags;
 892             else {
 893                 mask = MethodFlags;
 894             }
 895             // Imply STRICTFP if owner has STRICTFP set.
 896             if (((flags|implicit) & Flags.ABSTRACT) == 0)
 897               implicit |= sym.owner.flags_field & STRICTFP;
 898             break;
 899         case TYP:
 900             if (sym.isLocal()) {
 901                 mask = LocalClassFlags;
 902                 if (sym.name.isEmpty()) { // Anonymous class
 903                     // Anonymous classes in static methods are themselves static;
 904                     // that's why we admit STATIC here.
 905                     mask |= STATIC;
 906                     // JLS: Anonymous classes are final.
 907                     implicit |= FINAL;
 908                 }
 909                 if ((sym.owner.flags_field & STATIC) == 0 &&
 910                     (flags & ENUM) != 0)
 911                     log.error(pos, "enums.must.be.static");
 912             } else if (sym.owner.kind == TYP) {
 913                 mask = MemberClassFlags;
 914                 if (sym.owner.owner.kind == PCK ||
 915                     (sym.owner.flags_field & STATIC) != 0)
 916                     mask |= STATIC;
 917                 else if ((flags & ENUM) != 0)
 918                     log.error(pos, "enums.must.be.static");
 919                 // Nested interfaces and enums are always STATIC (Spec ???)
 920                 if ((flags & (INTERFACE | ENUM)) != 0 ) implicit = STATIC;
 921             } else {
 922                 mask = ClassFlags;
 923             }
 924             // Interfaces are always ABSTRACT
 925             if ((flags & INTERFACE) != 0) implicit |= ABSTRACT;
 926 
 927             if ((flags & ENUM) != 0) {
 928                 // enums can't be declared abstract or final
 929                 mask &= ~(ABSTRACT | FINAL);
 930                 implicit |= implicitEnumFinalFlag(tree);
 931             }
 932             // Imply STRICTFP if owner has STRICTFP set.
 933             implicit |= sym.owner.flags_field & STRICTFP;
 934             break;
 935         default:
 936             throw new AssertionError();
 937         }
 938         long illegal = flags & StandardFlags & ~mask;
 939         if (illegal != 0) {
 940             if ((illegal & INTERFACE) != 0) {
 941                 log.error(pos, "intf.not.allowed.here");
 942                 mask |= INTERFACE;
 943             }
 944             else {
 945                 log.error(pos,
 946                           "mod.not.allowed.here", asFlagSet(illegal));
 947             }
 948         }
 949         else if ((sym.kind == TYP ||
 950                   // ISSUE: Disallowing abstract&private is no longer appropriate
 951                   // in the presence of inner classes. Should it be deleted here?
 952                   checkDisjoint(pos, flags,
 953                                 ABSTRACT,
 954                                 PRIVATE | STATIC))
 955                  &&
 956                  checkDisjoint(pos, flags,
 957                                ABSTRACT | INTERFACE,
 958                                FINAL | NATIVE | SYNCHRONIZED)
 959                  &&
 960                  checkDisjoint(pos, flags,
 961                                PUBLIC,
 962                                PRIVATE | PROTECTED)
 963                  &&
 964                  checkDisjoint(pos, flags,
 965                                PRIVATE,
 966                                PUBLIC | PROTECTED)
 967                  &&
 968                  checkDisjoint(pos, flags,
 969                                FINAL,
 970                                VOLATILE)
 971                  &&
 972                  (sym.kind == TYP ||
 973                   checkDisjoint(pos, flags,
 974                                 ABSTRACT | NATIVE,
 975                                 STRICTFP))) {
 976             // skip
 977         }
 978         return flags & (mask | ~StandardFlags) | implicit;
 979     }
 980 
 981 
 982     /** Determine if this enum should be implicitly final.
 983      *
 984      *  If the enum has no specialized enum contants, it is final.
 985      *
 986      *  If the enum does have specialized enum contants, it is
 987      *  <i>not</i> final.
 988      */
 989     private long implicitEnumFinalFlag(JCTree tree) {
 990         if (tree.getTag() != JCTree.CLASSDEF) return 0;
 991         class SpecialTreeVisitor extends JCTree.Visitor {
 992             boolean specialized;
 993             SpecialTreeVisitor() {
 994                 this.specialized = false;
 995             };
 996 
 997             @Override
 998             public void visitTree(JCTree tree) { /* no-op */ }
 999 
1000             @Override
1001             public void visitVarDef(JCVariableDecl tree) {
1002                 if ((tree.mods.flags & ENUM) != 0) {
1003                     if (tree.init instanceof JCNewClass &&
1004                         ((JCNewClass) tree.init).def != null) {
1005                         specialized = true;
1006                     }
1007                 }
1008             }
1009         }
1010 
1011         SpecialTreeVisitor sts = new SpecialTreeVisitor();
1012         JCClassDecl cdef = (JCClassDecl) tree;
1013         for (JCTree defs: cdef.defs) {
1014             defs.accept(sts);
1015             if (sts.specialized) return 0;
1016         }
1017         return FINAL;
1018     }
1019 
1020 /* *************************************************************************
1021  * Type Validation
1022  **************************************************************************/
1023 
1024     /** Validate a type expression. That is,
1025      *  check that all type arguments of a parametric type are within
1026      *  their bounds. This must be done in a second phase after type attributon
1027      *  since a class might have a subclass as type parameter bound. E.g:
1028      *
1029      *  class B<A extends C> { ... }
1030      *  class C extends B<C> { ... }
1031      *
1032      *  and we can't make sure that the bound is already attributed because
1033      *  of possible cycles.
1034      *
1035      * Visitor method: Validate a type expression, if it is not null, catching
1036      *  and reporting any completion failures.
1037      */
1038     void validate(JCTree tree, Env<AttrContext> env) {
1039         validate(tree, env, true);
1040     }
1041     void validate(JCTree tree, Env<AttrContext> env, boolean checkRaw) {
1042         new Validator(env).validateTree(tree, checkRaw, true);
1043     }
1044 
1045     /** Visitor method: Validate a list of type expressions.
1046      */
1047     void validate(List<? extends JCTree> trees, Env<AttrContext> env) {
1048         for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
1049             validate(l.head, env);
1050     }
1051 
1052     /** A visitor class for type validation.
1053      */
1054     class Validator extends JCTree.Visitor {
1055 
1056         boolean isOuter;
1057         Env<AttrContext> env;
1058 
1059         Validator(Env<AttrContext> env) {
1060             this.env = env;
1061         }
1062 
1063         @Override
1064         public void visitTypeArray(JCArrayTypeTree tree) {
1065             tree.elemtype.accept(this);
1066         }
1067 
1068         @Override
1069         public void visitTypeApply(JCTypeApply tree) {
1070             if (tree.type.tag == CLASS) {
1071                 List<JCExpression> args = tree.arguments;
1072                 List<Type> forms = tree.type.tsym.type.getTypeArguments();
1073 
1074                 Type incompatibleArg = firstIncompatibleTypeArg(tree.type);
1075                 if (incompatibleArg != null) {
1076                     for (JCTree arg : tree.arguments) {
1077                         if (arg.type == incompatibleArg) {
1078                             log.error(arg, "not.within.bounds", incompatibleArg, forms.head);
1079                         }
1080                         forms = forms.tail;
1081                      }
1082                  }
1083 
1084                 forms = tree.type.tsym.type.getTypeArguments();
1085 
1086                 boolean is_java_lang_Class = tree.type.tsym.flatName() == names.java_lang_Class;
1087 
1088                 // For matching pairs of actual argument types `a' and
1089                 // formal type parameters with declared bound `b' ...
1090                 while (args.nonEmpty() && forms.nonEmpty()) {
1091                     validateTree(args.head,
1092                             !(isOuter && is_java_lang_Class),
1093                             false);
1094                     args = args.tail;
1095                     forms = forms.tail;
1096                 }
1097 
1098                 // Check that this type is either fully parameterized, or
1099                 // not parameterized at all.
1100                 if (tree.type.getEnclosingType().isRaw())
1101                     log.error(tree.pos(), "improperly.formed.type.inner.raw.param");
1102                 if (tree.clazz.getTag() == JCTree.SELECT)
1103                     visitSelectInternal((JCFieldAccess)tree.clazz);
1104             }
1105         }
1106 
1107         @Override
1108         public void visitTypeParameter(JCTypeParameter tree) {
1109             validateTrees(tree.bounds, true, isOuter);
1110             checkClassBounds(tree.pos(), tree.type);
1111         }
1112 
1113         @Override
1114         public void visitWildcard(JCWildcard tree) {
1115             if (tree.inner != null)
1116                 validateTree(tree.inner, true, isOuter);
1117         }
1118 
1119         @Override
1120         public void visitSelect(JCFieldAccess tree) {
1121             if (tree.type.tag == CLASS) {
1122                 visitSelectInternal(tree);
1123 
1124                 // Check that this type is either fully parameterized, or
1125                 // not parameterized at all.
1126                 if (tree.selected.type.isParameterized() && tree.type.tsym.type.getTypeArguments().nonEmpty())
1127                     log.error(tree.pos(), "improperly.formed.type.param.missing");
1128             }
1129         }
1130 
1131         public void visitSelectInternal(JCFieldAccess tree) {
1132             if (tree.type.tsym.isStatic() &&
1133                 tree.selected.type.isParameterized()) {
1134                 // The enclosing type is not a class, so we are
1135                 // looking at a static member type.  However, the
1136                 // qualifying expression is parameterized.
1137                 log.error(tree.pos(), "cant.select.static.class.from.param.type");
1138             } else {
1139                 // otherwise validate the rest of the expression
1140                 tree.selected.accept(this);
1141             }
1142         }
1143 
1144         /** Default visitor method: do nothing.
1145          */
1146         @Override
1147         public void visitTree(JCTree tree) {
1148         }
1149 
1150         public void validateTree(JCTree tree, boolean checkRaw, boolean isOuter) {
1151             try {
1152                 if (tree != null) {
1153                     this.isOuter = isOuter;
1154                     tree.accept(this);
1155                     if (checkRaw)
1156                         checkRaw(tree, env);
1157                 }
1158             } catch (CompletionFailure ex) {
1159                 completionError(tree.pos(), ex);
1160             }
1161         }
1162 
1163         public void validateTrees(List<? extends JCTree> trees, boolean checkRaw, boolean isOuter) {
1164             for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
1165                 validateTree(l.head, checkRaw, isOuter);
1166         }
1167 
1168         void checkRaw(JCTree tree, Env<AttrContext> env) {
1169             if (lint.isEnabled(LintCategory.RAW) &&
1170                 tree.type.tag == CLASS &&
1171                 !TreeInfo.isDiamond(tree) &&
1172                 !withinAnonConstr(env) &&
1173                 tree.type.isRaw()) {
1174                 log.warning(LintCategory.RAW,
1175                         tree.pos(), "raw.class.use", tree.type, tree.type.tsym.type);
1176             }
1177         }
1178 
1179         boolean withinAnonConstr(Env<AttrContext> env) {
1180             return env.enclClass.name.isEmpty() &&
1181                     env.enclMethod != null && env.enclMethod.name == names.init;
1182         }
1183     }
1184 
1185 /* *************************************************************************
1186  * Exception checking
1187  **************************************************************************/
1188 
1189     /* The following methods treat classes as sets that contain
1190      * the class itself and all their subclasses
1191      */
1192 
1193     /** Is given type a subtype of some of the types in given list?
1194      */
1195     boolean subset(Type t, List<Type> ts) {
1196         for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
1197             if (types.isSubtype(t, l.head)) return true;
1198         return false;
1199     }
1200 
1201     /** Is given type a subtype or supertype of
1202      *  some of the types in given list?
1203      */
1204     boolean intersects(Type t, List<Type> ts) {
1205         for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
1206             if (types.isSubtype(t, l.head) || types.isSubtype(l.head, t)) return true;
1207         return false;
1208     }
1209 
1210     /** Add type set to given type list, unless it is a subclass of some class
1211      *  in the list.
1212      */
1213     List<Type> incl(Type t, List<Type> ts) {
1214         return subset(t, ts) ? ts : excl(t, ts).prepend(t);
1215     }
1216 
1217     /** Remove type set from type set list.
1218      */
1219     List<Type> excl(Type t, List<Type> ts) {
1220         if (ts.isEmpty()) {
1221             return ts;
1222         } else {
1223             List<Type> ts1 = excl(t, ts.tail);
1224             if (types.isSubtype(ts.head, t)) return ts1;
1225             else if (ts1 == ts.tail) return ts;
1226             else return ts1.prepend(ts.head);
1227         }
1228     }
1229 
1230     /** Form the union of two type set lists.
1231      */
1232     List<Type> union(List<Type> ts1, List<Type> ts2) {
1233         List<Type> ts = ts1;
1234         for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
1235             ts = incl(l.head, ts);
1236         return ts;
1237     }
1238 
1239     /** Form the difference of two type lists.
1240      */
1241     List<Type> diff(List<Type> ts1, List<Type> ts2) {
1242         List<Type> ts = ts1;
1243         for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
1244             ts = excl(l.head, ts);
1245         return ts;
1246     }
1247 
1248     /** Form the intersection of two type lists.
1249      */
1250     public List<Type> intersect(List<Type> ts1, List<Type> ts2) {
1251         List<Type> ts = List.nil();
1252         for (List<Type> l = ts1; l.nonEmpty(); l = l.tail)
1253             if (subset(l.head, ts2)) ts = incl(l.head, ts);
1254         for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
1255             if (subset(l.head, ts1)) ts = incl(l.head, ts);
1256         return ts;
1257     }
1258 
1259     /** Is exc an exception symbol that need not be declared?
1260      */
1261     boolean isUnchecked(ClassSymbol exc) {
1262         return
1263             exc.kind == ERR ||
1264             exc.isSubClass(syms.errorType.tsym, types) ||
1265             exc.isSubClass(syms.runtimeExceptionType.tsym, types);
1266     }
1267 
1268     /** Is exc an exception type that need not be declared?
1269      */
1270     boolean isUnchecked(Type exc) {
1271         return
1272             (exc.tag == TYPEVAR) ? isUnchecked(types.supertype(exc)) :
1273             (exc.tag == CLASS) ? isUnchecked((ClassSymbol)exc.tsym) :
1274             exc.tag == BOT;
1275     }
1276 
1277     /** Same, but handling completion failures.
1278      */
1279     boolean isUnchecked(DiagnosticPosition pos, Type exc) {
1280         try {
1281             return isUnchecked(exc);
1282         } catch (CompletionFailure ex) {
1283             completionError(pos, ex);
1284             return true;
1285         }
1286     }
1287 
1288     /** Is exc handled by given exception list?
1289      */
1290     boolean isHandled(Type exc, List<Type> handled) {
1291         return isUnchecked(exc) || subset(exc, handled);
1292     }
1293 
1294     /** Return all exceptions in thrown list that are not in handled list.
1295      *  @param thrown     The list of thrown exceptions.
1296      *  @param handled    The list of handled exceptions.
1297      */
1298     List<Type> unhandled(List<Type> thrown, List<Type> handled) {
1299         List<Type> unhandled = List.nil();
1300         for (List<Type> l = thrown; l.nonEmpty(); l = l.tail)
1301             if (!isHandled(l.head, handled)) unhandled = unhandled.prepend(l.head);
1302         return unhandled;
1303     }
1304 
1305 /* *************************************************************************
1306  * Overriding/Implementation checking
1307  **************************************************************************/
1308 
1309     /** The level of access protection given by a flag set,
1310      *  where PRIVATE is highest and PUBLIC is lowest.
1311      */
1312     static int protection(long flags) {
1313         switch ((short)(flags & AccessFlags)) {
1314         case PRIVATE: return 3;
1315         case PROTECTED: return 1;
1316         default:
1317         case PUBLIC: return 0;
1318         case 0: return 2;
1319         }
1320     }
1321 
1322     /** A customized "cannot override" error message.
1323      *  @param m      The overriding method.
1324      *  @param other  The overridden method.
1325      *  @return       An internationalized string.
1326      */
1327     Object cannotOverride(MethodSymbol m, MethodSymbol other) {
1328         String key;
1329         if ((other.owner.flags() & INTERFACE) == 0)
1330             key = "cant.override";
1331         else if ((m.owner.flags() & INTERFACE) == 0)
1332             key = "cant.implement";
1333         else
1334             key = "clashes.with";
1335         return diags.fragment(key, m, m.location(), other, other.location());
1336     }
1337 
1338     /** A customized "override" warning message.
1339      *  @param m      The overriding method.
1340      *  @param other  The overridden method.
1341      *  @return       An internationalized string.
1342      */
1343     Object uncheckedOverrides(MethodSymbol m, MethodSymbol other) {
1344         String key;
1345         if ((other.owner.flags() & INTERFACE) == 0)
1346             key = "unchecked.override";
1347         else if ((m.owner.flags() & INTERFACE) == 0)
1348             key = "unchecked.implement";
1349         else
1350             key = "unchecked.clash.with";
1351         return diags.fragment(key, m, m.location(), other, other.location());
1352     }
1353 
1354     /** A customized "override" warning message.
1355      *  @param m      The overriding method.
1356      *  @param other  The overridden method.
1357      *  @return       An internationalized string.
1358      */
1359     Object varargsOverrides(MethodSymbol m, MethodSymbol other) {
1360         String key;
1361         if ((other.owner.flags() & INTERFACE) == 0)
1362             key = "varargs.override";
1363         else  if ((m.owner.flags() & INTERFACE) == 0)
1364             key = "varargs.implement";
1365         else
1366             key = "varargs.clash.with";
1367         return diags.fragment(key, m, m.location(), other, other.location());
1368     }
1369 
1370     /** Check that this method conforms with overridden method 'other'.
1371      *  where `origin' is the class where checking started.
1372      *  Complications:
1373      *  (1) Do not check overriding of synthetic methods
1374      *      (reason: they might be final).
1375      *      todo: check whether this is still necessary.
1376      *  (2) Admit the case where an interface proxy throws fewer exceptions
1377      *      than the method it implements. Augment the proxy methods with the
1378      *      undeclared exceptions in this case.
1379      *  (3) When generics are enabled, admit the case where an interface proxy
1380      *      has a result type
1381      *      extended by the result type of the method it implements.
1382      *      Change the proxies result type to the smaller type in this case.
1383      *
1384      *  @param tree         The tree from which positions
1385      *                      are extracted for errors.
1386      *  @param m            The overriding method.
1387      *  @param other        The overridden method.
1388      *  @param origin       The class of which the overriding method
1389      *                      is a member.
1390      */
1391     void checkOverride(JCTree tree,
1392                        MethodSymbol m,
1393                        MethodSymbol other,
1394                        ClassSymbol origin) {
1395         // Don't check overriding of synthetic methods or by bridge methods.
1396         if ((m.flags() & (SYNTHETIC|BRIDGE)) != 0 || (other.flags() & SYNTHETIC) != 0) {
1397             return;
1398         }
1399 
1400         // Error if static method overrides instance method (JLS 8.4.6.2).
1401         if ((m.flags() & STATIC) != 0 &&
1402                    (other.flags() & STATIC) == 0) {
1403             log.error(TreeInfo.diagnosticPositionFor(m, tree), "override.static",
1404                       cannotOverride(m, other));
1405             return;
1406         }
1407 
1408         // Error if instance method overrides static or final
1409         // method (JLS 8.4.6.1).
1410         if ((other.flags() & FINAL) != 0 ||
1411                  (m.flags() & STATIC) == 0 &&
1412                  (other.flags() & STATIC) != 0) {
1413             log.error(TreeInfo.diagnosticPositionFor(m, tree), "override.meth",
1414                       cannotOverride(m, other),
1415                       asFlagSet(other.flags() & (FINAL | STATIC)));
1416             return;
1417         }
1418 
1419         if ((m.owner.flags() & ANNOTATION) != 0) {
1420             // handled in validateAnnotationMethod
1421             return;
1422         }
1423 
1424         // Error if overriding method has weaker access (JLS 8.4.6.3).
1425         if ((origin.flags() & INTERFACE) == 0 &&
1426                  protection(m.flags()) > protection(other.flags())) {
1427             log.error(TreeInfo.diagnosticPositionFor(m, tree), "override.weaker.access",
1428                       cannotOverride(m, other),
1429                       other.flags() == 0 ?
1430                           Flag.PACKAGE :
1431                           asFlagSet(other.flags() & AccessFlags));
1432             return;
1433         }
1434 
1435         Type mt = types.memberType(origin.type, m);
1436         Type ot = types.memberType(origin.type, other);
1437         // Error if overriding result type is different
1438         // (or, in the case of generics mode, not a subtype) of
1439         // overridden result type. We have to rename any type parameters
1440         // before comparing types.
1441         List<Type> mtvars = mt.getTypeArguments();
1442         List<Type> otvars = ot.getTypeArguments();
1443         Type mtres = mt.getReturnType();
1444         Type otres = types.subst(ot.getReturnType(), otvars, mtvars);
1445 
1446         overrideWarner.clear();
1447         boolean resultTypesOK =
1448             types.returnTypeSubstitutable(mt, ot, otres, overrideWarner);
1449         if (!resultTypesOK) {
1450             if (!allowCovariantReturns &&
1451                 m.owner != origin &&
1452                 m.owner.isSubClass(other.owner, types)) {
1453                 // allow limited interoperability with covariant returns
1454             } else {
1455                 log.error(TreeInfo.diagnosticPositionFor(m, tree),
1456                           "override.incompatible.ret",
1457                           cannotOverride(m, other),
1458                           mtres, otres);
1459                 return;
1460             }
1461         } else if (overrideWarner.hasNonSilentLint(LintCategory.UNCHECKED)) {
1462             warnUnchecked(TreeInfo.diagnosticPositionFor(m, tree),
1463                     "override.unchecked.ret",
1464                     uncheckedOverrides(m, other),
1465                     mtres, otres);
1466         }
1467 
1468         // Error if overriding method throws an exception not reported
1469         // by overridden method.
1470         List<Type> otthrown = types.subst(ot.getThrownTypes(), otvars, mtvars);
1471         List<Type> unhandledErased = unhandled(mt.getThrownTypes(), types.erasure(otthrown));
1472         List<Type> unhandledUnerased = unhandled(mt.getThrownTypes(), otthrown);
1473         if (unhandledErased.nonEmpty()) {
1474             log.error(TreeInfo.diagnosticPositionFor(m, tree),
1475                       "override.meth.doesnt.throw",
1476                       cannotOverride(m, other),
1477                       unhandledUnerased.head);
1478             return;
1479         }
1480         else if (unhandledUnerased.nonEmpty()) {
1481             warnUnchecked(TreeInfo.diagnosticPositionFor(m, tree),
1482                           "override.unchecked.thrown",
1483                          cannotOverride(m, other),
1484                          unhandledUnerased.head);
1485             return;
1486         }
1487 
1488         // Optional warning if varargs don't agree
1489         if ((((m.flags() ^ other.flags()) & Flags.VARARGS) != 0)
1490             && lint.isEnabled(LintCategory.OVERRIDES)) {
1491             log.warning(TreeInfo.diagnosticPositionFor(m, tree),
1492                         ((m.flags() & Flags.VARARGS) != 0)
1493                         ? "override.varargs.missing"
1494                         : "override.varargs.extra",
1495                         varargsOverrides(m, other));
1496         }
1497 
1498         // Warn if instance method overrides bridge method (compiler spec ??)
1499         if ((other.flags() & BRIDGE) != 0) {
1500             log.warning(TreeInfo.diagnosticPositionFor(m, tree), "override.bridge",
1501                         uncheckedOverrides(m, other));
1502         }
1503 
1504         // Warn if a deprecated method overridden by a non-deprecated one.
1505         if (!isDeprecatedOverrideIgnorable(other, origin)) {
1506             checkDeprecated(TreeInfo.diagnosticPositionFor(m, tree), m, other);
1507         }
1508     }
1509     // where
1510         private boolean isDeprecatedOverrideIgnorable(MethodSymbol m, ClassSymbol origin) {
1511             // If the method, m, is defined in an interface, then ignore the issue if the method
1512             // is only inherited via a supertype and also implemented in the supertype,
1513             // because in that case, we will rediscover the issue when examining the method
1514             // in the supertype.
1515             // If the method, m, is not defined in an interface, then the only time we need to
1516             // address the issue is when the method is the supertype implemementation: any other
1517             // case, we will have dealt with when examining the supertype classes
1518             ClassSymbol mc = m.enclClass();
1519             Type st = types.supertype(origin.type);
1520             if (st.tag != CLASS)
1521                 return true;
1522             MethodSymbol stimpl = m.implementation((ClassSymbol)st.tsym, types, false);
1523 
1524             if (mc != null && ((mc.flags() & INTERFACE) != 0)) {
1525                 List<Type> intfs = types.interfaces(origin.type);
1526                 return (intfs.contains(mc.type) ? false : (stimpl != null));
1527             }
1528             else
1529                 return (stimpl != m);
1530         }
1531 
1532 
1533     // used to check if there were any unchecked conversions
1534     Warner overrideWarner = new Warner();
1535 
1536     /** Check that a class does not inherit two concrete methods
1537      *  with the same signature.
1538      *  @param pos          Position to be used for error reporting.
1539      *  @param site         The class type to be checked.
1540      */
1541     public void checkCompatibleConcretes(DiagnosticPosition pos, Type site) {
1542         Type sup = types.supertype(site);
1543         if (sup.tag != CLASS) return;
1544 
1545         for (Type t1 = sup;
1546              t1.tsym.type.isParameterized();
1547              t1 = types.supertype(t1)) {
1548             for (Scope.Entry e1 = t1.tsym.members().elems;
1549                  e1 != null;
1550                  e1 = e1.sibling) {
1551                 Symbol s1 = e1.sym;
1552                 if (s1.kind != MTH ||
1553                     (s1.flags() & (STATIC|SYNTHETIC|BRIDGE)) != 0 ||
1554                     !s1.isInheritedIn(site.tsym, types) ||
1555                     ((MethodSymbol)s1).implementation(site.tsym,
1556                                                       types,
1557                                                       true) != s1)
1558                     continue;
1559                 Type st1 = types.memberType(t1, s1);
1560                 int s1ArgsLength = st1.getParameterTypes().length();
1561                 if (st1 == s1.type) continue;
1562 
1563                 for (Type t2 = sup;
1564                      t2.tag == CLASS;
1565                      t2 = types.supertype(t2)) {
1566                     for (Scope.Entry e2 = t2.tsym.members().lookup(s1.name);
1567                          e2.scope != null;
1568                          e2 = e2.next()) {
1569                         Symbol s2 = e2.sym;
1570                         if (s2 == s1 ||
1571                             s2.kind != MTH ||
1572                             (s2.flags() & (STATIC|SYNTHETIC|BRIDGE)) != 0 ||
1573                             s2.type.getParameterTypes().length() != s1ArgsLength ||
1574                             !s2.isInheritedIn(site.tsym, types) ||
1575                             ((MethodSymbol)s2).implementation(site.tsym,
1576                                                               types,
1577                                                               true) != s2)
1578                             continue;
1579                         Type st2 = types.memberType(t2, s2);
1580                         if (types.overrideEquivalent(st1, st2))
1581                             log.error(pos, "concrete.inheritance.conflict",
1582                                       s1, t1, s2, t2, sup);
1583                     }
1584                 }
1585             }
1586         }
1587     }
1588 
1589     /** Check that classes (or interfaces) do not each define an abstract
1590      *  method with same name and arguments but incompatible return types.
1591      *  @param pos          Position to be used for error reporting.
1592      *  @param t1           The first argument type.
1593      *  @param t2           The second argument type.
1594      */
1595     public boolean checkCompatibleAbstracts(DiagnosticPosition pos,
1596                                             Type t1,
1597                                             Type t2) {
1598         return checkCompatibleAbstracts(pos, t1, t2,
1599                                         types.makeCompoundType(t1, t2));
1600     }
1601 
1602     public boolean checkCompatibleAbstracts(DiagnosticPosition pos,
1603                                             Type t1,
1604                                             Type t2,
1605                                             Type site) {
1606         return firstIncompatibility(pos, t1, t2, site) == null;
1607     }
1608 
1609     /** Return the first method which is defined with same args
1610      *  but different return types in two given interfaces, or null if none
1611      *  exists.
1612      *  @param t1     The first type.
1613      *  @param t2     The second type.
1614      *  @param site   The most derived type.
1615      *  @returns symbol from t2 that conflicts with one in t1.
1616      */
1617     private Symbol firstIncompatibility(DiagnosticPosition pos, Type t1, Type t2, Type site) {
1618         Map<TypeSymbol,Type> interfaces1 = new HashMap<TypeSymbol,Type>();
1619         closure(t1, interfaces1);
1620         Map<TypeSymbol,Type> interfaces2;
1621         if (t1 == t2)
1622             interfaces2 = interfaces1;
1623         else
1624             closure(t2, interfaces1, interfaces2 = new HashMap<TypeSymbol,Type>());
1625 
1626         for (Type t3 : interfaces1.values()) {
1627             for (Type t4 : interfaces2.values()) {
1628                 Symbol s = firstDirectIncompatibility(pos, t3, t4, site);
1629                 if (s != null) return s;
1630             }
1631         }
1632         return null;
1633     }
1634 
1635     /** Compute all the supertypes of t, indexed by type symbol. */
1636     private void closure(Type t, Map<TypeSymbol,Type> typeMap) {
1637         if (t.tag != CLASS) return;
1638         if (typeMap.put(t.tsym, t) == null) {
1639             closure(types.supertype(t), typeMap);
1640             for (Type i : types.interfaces(t))
1641                 closure(i, typeMap);
1642         }
1643     }
1644 
1645     /** Compute all the supertypes of t, indexed by type symbol (except thise in typesSkip). */
1646     private void closure(Type t, Map<TypeSymbol,Type> typesSkip, Map<TypeSymbol,Type> typeMap) {
1647         if (t.tag != CLASS) return;
1648         if (typesSkip.get(t.tsym) != null) return;
1649         if (typeMap.put(t.tsym, t) == null) {
1650             closure(types.supertype(t), typesSkip, typeMap);
1651             for (Type i : types.interfaces(t))
1652                 closure(i, typesSkip, typeMap);
1653         }
1654     }
1655 
1656     /** Return the first method in t2 that conflicts with a method from t1. */
1657     private Symbol firstDirectIncompatibility(DiagnosticPosition pos, Type t1, Type t2, Type site) {
1658         for (Scope.Entry e1 = t1.tsym.members().elems; e1 != null; e1 = e1.sibling) {
1659             Symbol s1 = e1.sym;
1660             Type st1 = null;
1661             if (s1.kind != MTH || !s1.isInheritedIn(site.tsym, types)) continue;
1662             Symbol impl = ((MethodSymbol)s1).implementation(site.tsym, types, false);
1663             if (impl != null && (impl.flags() & ABSTRACT) == 0) continue;
1664             for (Scope.Entry e2 = t2.tsym.members().lookup(s1.name); e2.scope != null; e2 = e2.next()) {
1665                 Symbol s2 = e2.sym;
1666                 if (s1 == s2) continue;
1667                 if (s2.kind != MTH || !s2.isInheritedIn(site.tsym, types)) continue;
1668                 if (st1 == null) st1 = types.memberType(t1, s1);
1669                 Type st2 = types.memberType(t2, s2);
1670                 if (types.overrideEquivalent(st1, st2)) {
1671                     List<Type> tvars1 = st1.getTypeArguments();
1672                     List<Type> tvars2 = st2.getTypeArguments();
1673                     Type rt1 = st1.getReturnType();
1674                     Type rt2 = types.subst(st2.getReturnType(), tvars2, tvars1);
1675                     boolean compat =
1676                         types.isSameType(rt1, rt2) ||
1677                         rt1.tag >= CLASS && rt2.tag >= CLASS &&
1678                         (types.covariantReturnType(rt1, rt2, Warner.noWarnings) ||
1679                          types.covariantReturnType(rt2, rt1, Warner.noWarnings)) ||
1680                          checkCommonOverriderIn(s1,s2,site);
1681                     if (!compat) {
1682                         log.error(pos, "types.incompatible.diff.ret",
1683                             t1, t2, s2.name +
1684                             "(" + types.memberType(t2, s2).getParameterTypes() + ")");
1685                         return s2;
1686                     }
1687                 } else if (checkNameClash((ClassSymbol)site.tsym, s1, s2) &&
1688                         !checkCommonOverriderIn(s1, s2, site)) {
1689                     log.error(pos,
1690                             "name.clash.same.erasure.no.override",
1691                             s1, s1.location(),
1692                             s2, s2.location());
1693                     return s2;
1694                 }
1695             }
1696         }
1697         return null;
1698     }
1699     //WHERE
1700     boolean checkCommonOverriderIn(Symbol s1, Symbol s2, Type site) {
1701         Map<TypeSymbol,Type> supertypes = new HashMap<TypeSymbol,Type>();
1702         Type st1 = types.memberType(site, s1);
1703         Type st2 = types.memberType(site, s2);
1704         closure(site, supertypes);
1705         for (Type t : supertypes.values()) {
1706             for (Scope.Entry e = t.tsym.members().lookup(s1.name); e.scope != null; e = e.next()) {
1707                 Symbol s3 = e.sym;
1708                 if (s3 == s1 || s3 == s2 || s3.kind != MTH || (s3.flags() & (BRIDGE|SYNTHETIC)) != 0) continue;
1709                 Type st3 = types.memberType(site,s3);
1710                 if (types.overrideEquivalent(st3, st1) && types.overrideEquivalent(st3, st2)) {
1711                     if (s3.owner == site.tsym) {
1712                         return true;
1713                     }
1714                     List<Type> tvars1 = st1.getTypeArguments();
1715                     List<Type> tvars2 = st2.getTypeArguments();
1716                     List<Type> tvars3 = st3.getTypeArguments();
1717                     Type rt1 = st1.getReturnType();
1718                     Type rt2 = st2.getReturnType();
1719                     Type rt13 = types.subst(st3.getReturnType(), tvars3, tvars1);
1720                     Type rt23 = types.subst(st3.getReturnType(), tvars3, tvars2);
1721                     boolean compat =
1722                         rt13.tag >= CLASS && rt23.tag >= CLASS &&
1723                         (types.covariantReturnType(rt13, rt1, Warner.noWarnings) &&
1724                          types.covariantReturnType(rt23, rt2, Warner.noWarnings));
1725                     if (compat)
1726                         return true;
1727                 }
1728             }
1729         }
1730         return false;
1731     }
1732 
1733     /** Check that a given method conforms with any method it overrides.
1734      *  @param tree         The tree from which positions are extracted
1735      *                      for errors.
1736      *  @param m            The overriding method.
1737      */
1738     void checkOverride(JCTree tree, MethodSymbol m) {
1739         ClassSymbol origin = (ClassSymbol)m.owner;
1740         if ((origin.flags() & ENUM) != 0 && names.finalize.equals(m.name))
1741             if (m.overrides(syms.enumFinalFinalize, origin, types, false)) {
1742                 log.error(tree.pos(), "enum.no.finalize");
1743                 return;
1744             }
1745         for (Type t = origin.type; t.tag == CLASS;
1746              t = types.supertype(t)) {
1747             if (t != origin.type) {
1748                 checkOverride(tree, t, origin, m);
1749             }
1750             for (Type t2 : types.interfaces(t)) {
1751                 checkOverride(tree, t2, origin, m);
1752             }
1753         }
1754     }
1755 
1756     void checkOverride(JCTree tree, Type site, ClassSymbol origin, MethodSymbol m) {
1757         TypeSymbol c = site.tsym;
1758         Scope.Entry e = c.members().lookup(m.name);
1759         while (e.scope != null) {
1760             if (m.overrides(e.sym, origin, types, false)) {
1761                 if ((e.sym.flags() & ABSTRACT) == 0) {
1762                     checkOverride(tree, m, (MethodSymbol)e.sym, origin);
1763                 }
1764             }
1765             e = e.next();
1766         }
1767     }
1768 
1769     private boolean checkNameClash(ClassSymbol origin, Symbol s1, Symbol s2) {
1770         ClashFilter cf = new ClashFilter(origin.type);
1771         return (cf.accepts(s1) &&
1772                 cf.accepts(s2) &&
1773                 types.hasSameArgs(s1.erasure(types), s2.erasure(types)));
1774     }
1775 
1776 
1777     /** Check that all abstract members of given class have definitions.
1778      *  @param pos          Position to be used for error reporting.
1779      *  @param c            The class.
1780      */
1781     void checkAllDefined(DiagnosticPosition pos, ClassSymbol c) {
1782         try {
1783             MethodSymbol undef = firstUndef(c, c);
1784             if (undef != null) {
1785                 if ((c.flags() & ENUM) != 0 &&
1786                     types.supertype(c.type).tsym == syms.enumSym &&
1787                     (c.flags() & FINAL) == 0) {
1788                     // add the ABSTRACT flag to an enum
1789                     c.flags_field |= ABSTRACT;
1790                 } else {
1791                     MethodSymbol undef1 =
1792                         new MethodSymbol(undef.flags(), undef.name,
1793                                          types.memberType(c.type, undef), undef.owner);
1794                     log.error(pos, "does.not.override.abstract",
1795                               c, undef1, undef1.location());
1796                 }
1797             }
1798         } catch (CompletionFailure ex) {
1799             completionError(pos, ex);
1800         }
1801     }
1802 //where
1803         /** Return first abstract member of class `c' that is not defined
1804          *  in `impl', null if there is none.
1805          */
1806         private MethodSymbol firstUndef(ClassSymbol impl, ClassSymbol c) {
1807             MethodSymbol undef = null;
1808             // Do not bother to search in classes that are not abstract,
1809             // since they cannot have abstract members.
1810             if (c == impl || (c.flags() & (ABSTRACT | INTERFACE)) != 0) {
1811                 Scope s = c.members();
1812                 for (Scope.Entry e = s.elems;
1813                      undef == null && e != null;
1814                      e = e.sibling) {
1815                     if (e.sym.kind == MTH &&
1816                         (e.sym.flags() & (ABSTRACT|IPROXY)) == ABSTRACT) {
1817                         MethodSymbol absmeth = (MethodSymbol)e.sym;
1818                         MethodSymbol implmeth = absmeth.implementation(impl, types, true);
1819                         if (implmeth == null || implmeth == absmeth)
1820                             undef = absmeth;
1821                     }
1822                 }
1823                 if (undef == null) {
1824                     Type st = types.supertype(c.type);
1825                     if (st.tag == CLASS)
1826                         undef = firstUndef(impl, (ClassSymbol)st.tsym);
1827                 }
1828                 for (List<Type> l = types.interfaces(c.type);
1829                      undef == null && l.nonEmpty();
1830                      l = l.tail) {
1831                     undef = firstUndef(impl, (ClassSymbol)l.head.tsym);
1832                 }
1833             }
1834             return undef;
1835         }
1836 
1837     void checkNonCyclicDecl(JCClassDecl tree) {
1838         CycleChecker cc = new CycleChecker();
1839         cc.scan(tree);
1840         if (!cc.errorFound && !cc.partialCheck) {
1841             tree.sym.flags_field |= ACYCLIC;
1842         }
1843     }
1844 
1845     class CycleChecker extends TreeScanner {
1846 
1847         List<Symbol> seenClasses = List.nil();
1848         boolean errorFound = false;
1849         boolean partialCheck = false;
1850 
1851         private void checkSymbol(DiagnosticPosition pos, Symbol sym) {
1852             if (sym != null && sym.kind == TYP) {
1853                 Env<AttrContext> classEnv = enter.getEnv((TypeSymbol)sym);
1854                 if (classEnv != null) {
1855                     DiagnosticSource prevSource = log.currentSource();
1856                     try {
1857                         log.useSource(classEnv.toplevel.sourcefile);
1858                         scan(classEnv.tree);
1859                     }
1860                     finally {
1861                         log.useSource(prevSource.getFile());
1862                     }
1863                 } else if (sym.kind == TYP) {
1864                     checkClass(pos, sym, List.<JCTree>nil());
1865                 }
1866             } else {
1867                 //not completed yet
1868                 partialCheck = true;
1869             }
1870         }
1871 
1872         @Override
1873         public void visitSelect(JCFieldAccess tree) {
1874             super.visitSelect(tree);
1875             checkSymbol(tree.pos(), tree.sym);
1876         }
1877 
1878         @Override
1879         public void visitIdent(JCIdent tree) {
1880             checkSymbol(tree.pos(), tree.sym);
1881         }
1882 
1883         @Override
1884         public void visitTypeApply(JCTypeApply tree) {
1885             scan(tree.clazz);
1886         }
1887 
1888         @Override
1889         public void visitTypeArray(JCArrayTypeTree tree) {
1890             scan(tree.elemtype);
1891         }
1892 
1893         @Override
1894         public void visitClassDef(JCClassDecl tree) {
1895             List<JCTree> supertypes = List.nil();
1896             if (tree.getExtendsClause() != null) {
1897                 supertypes = supertypes.prepend(tree.getExtendsClause());
1898             }
1899             if (tree.getImplementsClause() != null) {
1900                 for (JCTree intf : tree.getImplementsClause()) {
1901                     supertypes = supertypes.prepend(intf);
1902                 }
1903             }
1904             checkClass(tree.pos(), tree.sym, supertypes);
1905         }
1906 
1907         void checkClass(DiagnosticPosition pos, Symbol c, List<JCTree> supertypes) {
1908             if ((c.flags_field & ACYCLIC) != 0)
1909                 return;
1910             if (seenClasses.contains(c)) {
1911                 errorFound = true;
1912                 noteCyclic(pos, (ClassSymbol)c);
1913             } else if (!c.type.isErroneous()) {
1914                 try {
1915                     seenClasses = seenClasses.prepend(c);
1916                     if (c.type.tag == CLASS) {
1917                         if (supertypes.nonEmpty()) {
1918                             scan(supertypes);
1919                         }
1920                         else {
1921                             ClassType ct = (ClassType)c.type;
1922                             if (ct.supertype_field == null ||
1923                                     ct.interfaces_field == null) {
1924                                 //not completed yet
1925                                 partialCheck = true;
1926                                 return;
1927                             }
1928                             checkSymbol(pos, ct.supertype_field.tsym);
1929                             for (Type intf : ct.interfaces_field) {
1930                                 checkSymbol(pos, intf.tsym);
1931                             }
1932                         }
1933                         if (c.owner.kind == TYP) {
1934                             checkSymbol(pos, c.owner);
1935                         }
1936                     }
1937                 } finally {
1938                     seenClasses = seenClasses.tail;
1939                 }
1940             }
1941         }
1942     }
1943 
1944     /** Check for cyclic references. Issue an error if the
1945      *  symbol of the type referred to has a LOCKED flag set.
1946      *
1947      *  @param pos      Position to be used for error reporting.
1948      *  @param t        The type referred to.
1949      */
1950     void checkNonCyclic(DiagnosticPosition pos, Type t) {
1951         checkNonCyclicInternal(pos, t);
1952     }
1953 
1954 
1955     void checkNonCyclic(DiagnosticPosition pos, TypeVar t) {
1956         checkNonCyclic1(pos, t, List.<TypeVar>nil());
1957     }
1958 
1959     private void checkNonCyclic1(DiagnosticPosition pos, Type t, List<TypeVar> seen) {
1960         final TypeVar tv;
1961         if  (t.tag == TYPEVAR && (t.tsym.flags() & UNATTRIBUTED) != 0)
1962             return;
1963         if (seen.contains(t)) {
1964             tv = (TypeVar)t;
1965             tv.bound = types.createErrorType(t);
1966             log.error(pos, "cyclic.inheritance", t);
1967         } else if (t.tag == TYPEVAR) {
1968             tv = (TypeVar)t;
1969             seen = seen.prepend(tv);
1970             for (Type b : types.getBounds(tv))
1971                 checkNonCyclic1(pos, b, seen);
1972         }
1973     }
1974 
1975     /** Check for cyclic references. Issue an error if the
1976      *  symbol of the type referred to has a LOCKED flag set.
1977      *
1978      *  @param pos      Position to be used for error reporting.
1979      *  @param t        The type referred to.
1980      *  @returns        True if the check completed on all attributed classes
1981      */
1982     private boolean checkNonCyclicInternal(DiagnosticPosition pos, Type t) {
1983         boolean complete = true; // was the check complete?
1984         //- System.err.println("checkNonCyclicInternal("+t+");");//DEBUG
1985         Symbol c = t.tsym;
1986         if ((c.flags_field & ACYCLIC) != 0) return true;
1987 
1988         if ((c.flags_field & LOCKED) != 0) {
1989             noteCyclic(pos, (ClassSymbol)c);
1990         } else if (!c.type.isErroneous()) {
1991             try {
1992                 c.flags_field |= LOCKED;
1993                 if (c.type.tag == CLASS) {
1994                     ClassType clazz = (ClassType)c.type;
1995                     if (clazz.interfaces_field != null)
1996                         for (List<Type> l=clazz.interfaces_field; l.nonEmpty(); l=l.tail)
1997                             complete &= checkNonCyclicInternal(pos, l.head);
1998                     if (clazz.supertype_field != null) {
1999                         Type st = clazz.supertype_field;
2000                         if (st != null && st.tag == CLASS)
2001                             complete &= checkNonCyclicInternal(pos, st);
2002                     }
2003                     if (c.owner.kind == TYP)
2004                         complete &= checkNonCyclicInternal(pos, c.owner.type);
2005                 }
2006             } finally {
2007                 c.flags_field &= ~LOCKED;
2008             }
2009         }
2010         if (complete)
2011             complete = ((c.flags_field & UNATTRIBUTED) == 0) && c.completer == null;
2012         if (complete) c.flags_field |= ACYCLIC;
2013         return complete;
2014     }
2015 
2016     /** Note that we found an inheritance cycle. */
2017     private void noteCyclic(DiagnosticPosition pos, ClassSymbol c) {
2018         log.error(pos, "cyclic.inheritance", c);
2019         for (List<Type> l=types.interfaces(c.type); l.nonEmpty(); l=l.tail)
2020             l.head = types.createErrorType((ClassSymbol)l.head.tsym, Type.noType);
2021         Type st = types.supertype(c.type);
2022         if (st.tag == CLASS)
2023             ((ClassType)c.type).supertype_field = types.createErrorType((ClassSymbol)st.tsym, Type.noType);
2024         c.type = types.createErrorType(c, c.type);
2025         c.flags_field |= ACYCLIC;
2026     }
2027 
2028     /** Check that all methods which implement some
2029      *  method conform to the method they implement.
2030      *  @param tree         The class definition whose members are checked.
2031      */
2032     void checkImplementations(JCClassDecl tree) {
2033         checkImplementations(tree, tree.sym);
2034     }
2035 //where
2036         /** Check that all methods which implement some
2037          *  method in `ic' conform to the method they implement.
2038          */
2039         void checkImplementations(JCClassDecl tree, ClassSymbol ic) {
2040             ClassSymbol origin = tree.sym;
2041             for (List<Type> l = types.closure(ic.type); l.nonEmpty(); l = l.tail) {
2042                 ClassSymbol lc = (ClassSymbol)l.head.tsym;
2043                 if ((allowGenerics || origin != lc) && (lc.flags() & ABSTRACT) != 0) {
2044                     for (Scope.Entry e=lc.members().elems; e != null; e=e.sibling) {
2045                         if (e.sym.kind == MTH &&
2046                             (e.sym.flags() & (STATIC|ABSTRACT)) == ABSTRACT) {
2047                             MethodSymbol absmeth = (MethodSymbol)e.sym;
2048                             MethodSymbol implmeth = absmeth.implementation(origin, types, false);
2049                             if (implmeth != null && implmeth != absmeth &&
2050                                 (implmeth.owner.flags() & INTERFACE) ==
2051                                 (origin.flags() & INTERFACE)) {
2052                                 // don't check if implmeth is in a class, yet
2053                                 // origin is an interface. This case arises only
2054                                 // if implmeth is declared in Object. The reason is
2055                                 // that interfaces really don't inherit from
2056                                 // Object it's just that the compiler represents
2057                                 // things that way.
2058                                 checkOverride(tree, implmeth, absmeth, origin);
2059                             }
2060                         }
2061                     }
2062                 }
2063             }
2064         }
2065 
2066     /** Check that all abstract methods implemented by a class are
2067      *  mutually compatible.
2068      *  @param pos          Position to be used for error reporting.
2069      *  @param c            The class whose interfaces are checked.
2070      */
2071     void checkCompatibleSupertypes(DiagnosticPosition pos, Type c) {
2072         List<Type> supertypes = types.interfaces(c);
2073         Type supertype = types.supertype(c);
2074         if (supertype.tag == CLASS &&
2075             (supertype.tsym.flags() & ABSTRACT) != 0)
2076             supertypes = supertypes.prepend(supertype);
2077         for (List<Type> l = supertypes; l.nonEmpty(); l = l.tail) {
2078             if (allowGenerics && !l.head.getTypeArguments().isEmpty() &&
2079                 !checkCompatibleAbstracts(pos, l.head, l.head, c))
2080                 return;
2081             for (List<Type> m = supertypes; m != l; m = m.tail)
2082                 if (!checkCompatibleAbstracts(pos, l.head, m.head, c))
2083                     return;
2084         }
2085         checkCompatibleConcretes(pos, c);
2086     }
2087 
2088     void checkConflicts(DiagnosticPosition pos, Symbol sym, TypeSymbol c) {
2089         for (Type ct = c.type; ct != Type.noType ; ct = types.supertype(ct)) {
2090             for (Scope.Entry e = ct.tsym.members().lookup(sym.name); e.scope == ct.tsym.members(); e = e.next()) {
2091                 // VM allows methods and variables with differing types
2092                 if (sym.kind == e.sym.kind &&
2093                     types.isSameType(types.erasure(sym.type), types.erasure(e.sym.type)) &&
2094                     sym != e.sym &&
2095                     (sym.flags() & Flags.SYNTHETIC) != (e.sym.flags() & Flags.SYNTHETIC) &&
2096                     (sym.flags() & IPROXY) == 0 && (e.sym.flags() & IPROXY) == 0 &&
2097                     (sym.flags() & BRIDGE) == 0 && (e.sym.flags() & BRIDGE) == 0) {
2098                     syntheticError(pos, (e.sym.flags() & SYNTHETIC) == 0 ? e.sym : sym);
2099                     return;
2100                 }
2101             }
2102         }
2103     }
2104 
2105     /** Check that all non-override equivalent methods accessible from 'site'
2106      *  are mutually compatible (JLS 8.4.8/9.4.1).
2107      *
2108      *  @param pos  Position to be used for error reporting.
2109      *  @param site The class whose methods are checked.
2110      *  @param sym  The method symbol to be checked.
2111      */
2112     void checkOverrideClashes(DiagnosticPosition pos, Type site, MethodSymbol sym) {
2113          ClashFilter cf = new ClashFilter(site);
2114          //for each method m1 that is a member of 'site'...
2115          for (Symbol s1 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
2116             //...find another method m2 that is overridden (directly or indirectly)
2117             //by method 'sym' in 'site'
2118             for (Symbol s2 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
2119                 if (s1 == s2 || !sym.overrides(s2, site.tsym, types, false)) continue;
2120                 //if (i) the signature of 'sym' is not a subsignature of m1 (seen as
2121                 //a member of 'site') and (ii) m1 has the same erasure as m2, issue an error
2122                 if (!types.isSubSignature(sym.type, types.memberType(site, s1), false) &&
2123                         types.hasSameArgs(s1.erasure(types), s2.erasure(types))) {
2124                     sym.flags_field |= CLASH;
2125                     String key = s2 == sym ?
2126                             "name.clash.same.erasure.no.override" :
2127                             "name.clash.same.erasure.no.override.1";
2128                     log.error(pos,
2129                             key,
2130                             sym, sym.location(),
2131                             s1, s1.location(),
2132                             s2, s2.location());
2133                     return;
2134                 }
2135             }
2136         }
2137     }
2138 
2139 
2140 
2141     /** Check that all static methods accessible from 'site' are
2142      *  mutually compatible (JLS 8.4.8).
2143      *
2144      *  @param pos  Position to be used for error reporting.
2145      *  @param site The class whose methods are checked.
2146      *  @param sym  The method symbol to be checked.
2147      */
2148     void checkHideClashes(DiagnosticPosition pos, Type site, MethodSymbol sym) {
2149         ClashFilter cf = new ClashFilter(site);
2150         //for each method m1 that is a member of 'site'...
2151         for (Symbol s : types.membersClosure(site, true).getElementsByName(sym.name, cf)) {
2152             //if (i) the signature of 'sym' is not a subsignature of m1 (seen as
2153             //a member of 'site') and (ii) 'sym' has the same erasure as m1, issue an error
2154             if (!types.isSubSignature(sym.type, types.memberType(site, s), false) &&
2155                     types.hasSameArgs(s.erasure(types), sym.erasure(types))) {
2156                 log.error(pos,
2157                         "name.clash.same.erasure.no.hide",
2158                         sym, sym.location(),
2159                         s, s.location());
2160                 return;
2161              }
2162          }
2163      }
2164 
2165      //where
2166      private class ClashFilter implements Filter<Symbol> {
2167 
2168          Type site;
2169 
2170          ClashFilter(Type site) {
2171              this.site = site;
2172          }
2173 
2174          boolean shouldSkip(Symbol s) {
2175              return (s.flags() & CLASH) != 0 &&
2176                 s.owner == site.tsym;
2177          }
2178 
2179          public boolean accepts(Symbol s) {
2180              return s.kind == MTH &&
2181                      (s.flags() & SYNTHETIC) == 0 &&
2182                      !shouldSkip(s) &&
2183                      s.isInheritedIn(site.tsym, types) &&
2184                      !s.isConstructor();
2185          }
2186      }
2187 
2188     /** Report a conflict between a user symbol and a synthetic symbol.
2189      */
2190     private void syntheticError(DiagnosticPosition pos, Symbol sym) {
2191         if (!sym.type.isErroneous()) {
2192             if (warnOnSyntheticConflicts) {
2193                 log.warning(pos, "synthetic.name.conflict", sym, sym.location());
2194             }
2195             else {
2196                 log.error(pos, "synthetic.name.conflict", sym, sym.location());
2197             }
2198         }
2199     }
2200 
2201     /** Check that class c does not implement directly or indirectly
2202      *  the same parameterized interface with two different argument lists.
2203      *  @param pos          Position to be used for error reporting.
2204      *  @param type         The type whose interfaces are checked.
2205      */
2206     void checkClassBounds(DiagnosticPosition pos, Type type) {
2207         checkClassBounds(pos, new HashMap<TypeSymbol,Type>(), type);
2208     }
2209 //where
2210         /** Enter all interfaces of type `type' into the hash table `seensofar'
2211          *  with their class symbol as key and their type as value. Make
2212          *  sure no class is entered with two different types.
2213          */
2214         void checkClassBounds(DiagnosticPosition pos,
2215                               Map<TypeSymbol,Type> seensofar,
2216                               Type type) {
2217             if (type.isErroneous()) return;
2218             for (List<Type> l = types.interfaces(type); l.nonEmpty(); l = l.tail) {
2219                 Type it = l.head;
2220                 Type oldit = seensofar.put(it.tsym, it);
2221                 if (oldit != null) {
2222                     List<Type> oldparams = oldit.allparams();
2223                     List<Type> newparams = it.allparams();
2224                     if (!types.containsTypeEquivalent(oldparams, newparams))
2225                         log.error(pos, "cant.inherit.diff.arg",
2226                                   it.tsym, Type.toString(oldparams),
2227                                   Type.toString(newparams));
2228                 }
2229                 checkClassBounds(pos, seensofar, it);
2230             }
2231             Type st = types.supertype(type);
2232             if (st != null) checkClassBounds(pos, seensofar, st);
2233         }
2234 
2235     /** Enter interface into into set.
2236      *  If it existed already, issue a "repeated interface" error.
2237      */
2238     void checkNotRepeated(DiagnosticPosition pos, Type it, Set<Type> its) {
2239         if (its.contains(it))
2240             log.error(pos, "repeated.interface");
2241         else {
2242             its.add(it);
2243         }
2244     }
2245 
2246 /* *************************************************************************
2247  * Check annotations
2248  **************************************************************************/
2249 
2250     /**
2251      * Recursively validate annotations values
2252      */
2253     void validateAnnotationTree(JCTree tree) {
2254         class AnnotationValidator extends TreeScanner {
2255             @Override
2256             public void visitAnnotation(JCAnnotation tree) {
2257                 if (!tree.type.isErroneous()) {
2258                     super.visitAnnotation(tree);
2259                     validateAnnotation(tree);
2260                 }
2261             }
2262         }
2263         tree.accept(new AnnotationValidator());
2264     }
2265 
2266     /** Annotation types are restricted to primitives, String, an
2267      *  enum, an annotation, Class, Class<?>, Class<? extends
2268      *  Anything>, arrays of the preceding.
2269      */
2270     void validateAnnotationType(JCTree restype) {
2271         // restype may be null if an error occurred, so don't bother validating it
2272         if (restype != null) {
2273             validateAnnotationType(restype.pos(), restype.type);
2274         }
2275     }
2276 
2277     void validateAnnotationType(DiagnosticPosition pos, Type type) {
2278         if (type.isPrimitive()) return;
2279         if (types.isSameType(type, syms.stringType)) return;
2280         if ((type.tsym.flags() & Flags.ENUM) != 0) return;
2281         if ((type.tsym.flags() & Flags.ANNOTATION) != 0) return;
2282         if (types.lowerBound(type).tsym == syms.classType.tsym) return;
2283         if (types.isArray(type) && !types.isArray(types.elemtype(type))) {
2284             validateAnnotationType(pos, types.elemtype(type));
2285             return;
2286         }
2287         log.error(pos, "invalid.annotation.member.type");
2288     }
2289 
2290     /**
2291      * "It is also a compile-time error if any method declared in an
2292      * annotation type has a signature that is override-equivalent to
2293      * that of any public or protected method declared in class Object
2294      * or in the interface annotation.Annotation."
2295      *
2296      * @jls 9.6 Annotation Types
2297      */
2298     void validateAnnotationMethod(DiagnosticPosition pos, MethodSymbol m) {
2299         for (Type sup = syms.annotationType; sup.tag == CLASS; sup = types.supertype(sup)) {
2300             Scope s = sup.tsym.members();
2301             for (Scope.Entry e = s.lookup(m.name); e.scope != null; e = e.next()) {
2302                 if (e.sym.kind == MTH &&
2303                     (e.sym.flags() & (PUBLIC | PROTECTED)) != 0 &&
2304                     types.overrideEquivalent(m.type, e.sym.type))
2305                     log.error(pos, "intf.annotation.member.clash", e.sym, sup);
2306             }
2307         }
2308     }
2309 
2310     /** Check the annotations of a symbol.
2311      */
2312     public void validateAnnotations(List<JCAnnotation> annotations, Symbol s) {
2313         if (skipAnnotations) return;
2314         for (JCAnnotation a : annotations)
2315             validateAnnotation(a, s);
2316     }
2317 
2318     /** Check an annotation of a symbol.
2319      */
2320     public void validateAnnotation(JCAnnotation a, Symbol s) {
2321         validateAnnotationTree(a);
2322 
2323         if (!annotationApplicable(a, s))
2324             log.error(a.pos(), "annotation.type.not.applicable");
2325 
2326         if (a.annotationType.type.tsym == syms.overrideType.tsym) {
2327             if (!isOverrider(s))
2328                 log.error(a.pos(), "method.does.not.override.superclass");
2329         }
2330     }
2331 
2332     /** Is s a method symbol that overrides a method in a superclass? */
2333     boolean isOverrider(Symbol s) {
2334         if (s.kind != MTH || s.isStatic())
2335             return false;
2336         MethodSymbol m = (MethodSymbol)s;
2337         TypeSymbol owner = (TypeSymbol)m.owner;
2338         for (Type sup : types.closure(owner.type)) {
2339             if (sup == owner.type)
2340                 continue; // skip "this"
2341             Scope scope = sup.tsym.members();
2342             for (Scope.Entry e = scope.lookup(m.name); e.scope != null; e = e.next()) {
2343                 if (!e.sym.isStatic() && m.overrides(e.sym, owner, types, true))
2344                     return true;
2345             }
2346         }
2347         return false;
2348     }
2349 
2350     /** Is the annotation applicable to the symbol? */
2351     boolean annotationApplicable(JCAnnotation a, Symbol s) {
2352         Attribute.Compound atTarget =
2353             a.annotationType.type.tsym.attribute(syms.annotationTargetType.tsym);
2354         if (atTarget == null) return true;
2355         Attribute atValue = atTarget.member(names.value);
2356         if (!(atValue instanceof Attribute.Array)) return true; // error recovery
2357         Attribute.Array arr = (Attribute.Array) atValue;
2358         for (Attribute app : arr.values) {
2359             if (!(app instanceof Attribute.Enum)) return true; // recovery
2360             Attribute.Enum e = (Attribute.Enum) app;
2361             if (e.value.name == names.TYPE)
2362                 { if (s.kind == TYP) return true; }
2363             else if (e.value.name == names.FIELD)
2364                 { if (s.kind == VAR && s.owner.kind != MTH) return true; }
2365             else if (e.value.name == names.METHOD)
2366                 { if (s.kind == MTH && !s.isConstructor()) return true; }
2367             else if (e.value.name == names.PARAMETER)
2368                 { if (s.kind == VAR &&
2369                       s.owner.kind == MTH &&
2370                       (s.flags() & PARAMETER) != 0)
2371                     return true;
2372                 }
2373             else if (e.value.name == names.CONSTRUCTOR)
2374                 { if (s.kind == MTH && s.isConstructor()) return true; }
2375             else if (e.value.name == names.LOCAL_VARIABLE)
2376                 { if (s.kind == VAR && s.owner.kind == MTH &&
2377                       (s.flags() & PARAMETER) == 0)
2378                     return true;
2379                 }
2380             else if (e.value.name == names.ANNOTATION_TYPE)
2381                 { if (s.kind == TYP && (s.flags() & ANNOTATION) != 0)
2382                     return true;
2383                 }
2384             else if (e.value.name == names.PACKAGE)
2385                 { if (s.kind == PCK) return true; }
2386             else if (e.value.name == names.TYPE_USE)
2387                 { if (s.kind == TYP ||
2388                       s.kind == VAR ||
2389                       (s.kind == MTH && !s.isConstructor() &&
2390                        s.type.getReturnType().tag != VOID))
2391                     return true;
2392                 }
2393             else
2394                 return true; // recovery
2395         }
2396         return false;
2397     }
2398 
2399     /** Check an annotation value.
2400      */
2401     public void validateAnnotation(JCAnnotation a) {
2402         // collect an inventory of the members (sorted alphabetically)
2403         Set<MethodSymbol> members = new TreeSet<MethodSymbol>(new Comparator<Symbol>() {
2404             public int compare(Symbol t, Symbol t1) {
2405                 return t.name.compareTo(t1.name);
2406             }
2407         });
2408         for (Scope.Entry e = a.annotationType.type.tsym.members().elems;
2409              e != null;
2410              e = e.sibling)
2411             if (e.sym.kind == MTH)
2412                 members.add((MethodSymbol) e.sym);
2413 
2414         // count them off as they're annotated
2415         for (JCTree arg : a.args) {
2416             if (arg.getTag() != JCTree.ASSIGN) continue; // recovery
2417             JCAssign assign = (JCAssign) arg;
2418             Symbol m = TreeInfo.symbol(assign.lhs);
2419             if (m == null || m.type.isErroneous()) continue;
2420             if (!members.remove(m))
2421                 log.error(assign.lhs.pos(), "duplicate.annotation.member.value",
2422                           m.name, a.type);
2423         }
2424 
2425         // all the remaining ones better have default values
2426         ListBuffer<Name> missingDefaults = ListBuffer.lb();
2427         for (MethodSymbol m : members) {
2428             if (m.defaultValue == null && !m.type.isErroneous()) {
2429                 missingDefaults.append(m.name);
2430             }
2431         }
2432         if (missingDefaults.nonEmpty()) {
2433             String key = (missingDefaults.size() > 1)
2434                     ? "annotation.missing.default.value.1"
2435                     : "annotation.missing.default.value";
2436             log.error(a.pos(), key, a.type, missingDefaults);
2437         }
2438 
2439         // special case: java.lang.annotation.Target must not have
2440         // repeated values in its value member
2441         if (a.annotationType.type.tsym != syms.annotationTargetType.tsym ||
2442             a.args.tail == null)
2443             return;
2444 
2445         if (a.args.head.getTag() != JCTree.ASSIGN) return; // error recovery
2446         JCAssign assign = (JCAssign) a.args.head;
2447         Symbol m = TreeInfo.symbol(assign.lhs);
2448         if (m.name != names.value) return;
2449         JCTree rhs = assign.rhs;
2450         if (rhs.getTag() != JCTree.NEWARRAY) return;
2451         JCNewArray na = (JCNewArray) rhs;
2452         Set<Symbol> targets = new HashSet<Symbol>();
2453         for (JCTree elem : na.elems) {
2454             if (!targets.add(TreeInfo.symbol(elem))) {
2455                 log.error(elem.pos(), "repeated.annotation.target");
2456             }
2457         }
2458     }
2459 
2460     void checkDeprecatedAnnotation(DiagnosticPosition pos, Symbol s) {
2461         if (allowAnnotations &&
2462             lint.isEnabled(LintCategory.DEP_ANN) &&
2463             (s.flags() & DEPRECATED) != 0 &&
2464             !syms.deprecatedType.isErroneous() &&
2465             s.attribute(syms.deprecatedType.tsym) == null) {
2466             log.warning(LintCategory.DEP_ANN,
2467                     pos, "missing.deprecated.annotation");
2468         }
2469     }
2470 
2471     void checkDeprecated(final DiagnosticPosition pos, final Symbol other, final Symbol s) {
2472         if ((s.flags() & DEPRECATED) != 0 &&
2473                 (other.flags() & DEPRECATED) == 0 &&
2474                 s.outermostClass() != other.outermostClass()) {
2475             deferredLintHandler.report(new DeferredLintHandler.LintLogger() {
2476                 @Override
2477                 public void report() {
2478                     warnDeprecated(pos, s);
2479                 }
2480             });
2481         };
2482     }
2483 
2484     void checkSunAPI(final DiagnosticPosition pos, final Symbol s) {
2485         if ((s.flags() & PROPRIETARY) != 0) {
2486             deferredLintHandler.report(new DeferredLintHandler.LintLogger() {
2487                 public void report() {
2488                     if (enableSunApiLintControl)
2489                       warnSunApi(pos, "sun.proprietary", s);
2490                     else
2491                       log.strictWarning(pos, "sun.proprietary", s);
2492                 }
2493             });
2494         }
2495     }
2496 
2497 /* *************************************************************************
2498  * Check for recursive annotation elements.
2499  **************************************************************************/
2500 
2501     /** Check for cycles in the graph of annotation elements.
2502      */
2503     void checkNonCyclicElements(JCClassDecl tree) {
2504         if ((tree.sym.flags_field & ANNOTATION) == 0) return;
2505         Assert.check((tree.sym.flags_field & LOCKED) == 0);
2506         try {
2507             tree.sym.flags_field |= LOCKED;
2508             for (JCTree def : tree.defs) {
2509                 if (def.getTag() != JCTree.METHODDEF) continue;
2510                 JCMethodDecl meth = (JCMethodDecl)def;
2511                 checkAnnotationResType(meth.pos(), meth.restype.type);
2512             }
2513         } finally {
2514             tree.sym.flags_field &= ~LOCKED;
2515             tree.sym.flags_field |= ACYCLIC_ANN;
2516         }
2517     }
2518 
2519     void checkNonCyclicElementsInternal(DiagnosticPosition pos, TypeSymbol tsym) {
2520         if ((tsym.flags_field & ACYCLIC_ANN) != 0)
2521             return;
2522         if ((tsym.flags_field & LOCKED) != 0) {
2523             log.error(pos, "cyclic.annotation.element");
2524             return;
2525         }
2526         try {
2527             tsym.flags_field |= LOCKED;
2528             for (Scope.Entry e = tsym.members().elems; e != null; e = e.sibling) {
2529                 Symbol s = e.sym;
2530                 if (s.kind != Kinds.MTH)
2531                     continue;
2532                 checkAnnotationResType(pos, ((MethodSymbol)s).type.getReturnType());
2533             }
2534         } finally {
2535             tsym.flags_field &= ~LOCKED;
2536             tsym.flags_field |= ACYCLIC_ANN;
2537         }
2538     }
2539 
2540     void checkAnnotationResType(DiagnosticPosition pos, Type type) {
2541         switch (type.tag) {
2542         case TypeTags.CLASS:
2543             if ((type.tsym.flags() & ANNOTATION) != 0)
2544                 checkNonCyclicElementsInternal(pos, type.tsym);
2545             break;
2546         case TypeTags.ARRAY:
2547             checkAnnotationResType(pos, types.elemtype(type));
2548             break;
2549         default:
2550             break; // int etc
2551         }
2552     }
2553 
2554 /* *************************************************************************
2555  * Check for cycles in the constructor call graph.
2556  **************************************************************************/
2557 
2558     /** Check for cycles in the graph of constructors calling other
2559      *  constructors.
2560      */
2561     void checkCyclicConstructors(JCClassDecl tree) {
2562         Map<Symbol,Symbol> callMap = new HashMap<Symbol, Symbol>();
2563 
2564         // enter each constructor this-call into the map
2565         for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
2566             JCMethodInvocation app = TreeInfo.firstConstructorCall(l.head);
2567             if (app == null) continue;
2568             JCMethodDecl meth = (JCMethodDecl) l.head;
2569             if (TreeInfo.name(app.meth) == names._this) {
2570                 callMap.put(meth.sym, TreeInfo.symbol(app.meth));
2571             } else {
2572                 meth.sym.flags_field |= ACYCLIC;
2573             }
2574         }
2575 
2576         // Check for cycles in the map
2577         Symbol[] ctors = new Symbol[0];
2578         ctors = callMap.keySet().toArray(ctors);
2579         for (Symbol caller : ctors) {
2580             checkCyclicConstructor(tree, caller, callMap);
2581         }
2582     }
2583 
2584     /** Look in the map to see if the given constructor is part of a
2585      *  call cycle.
2586      */
2587     private void checkCyclicConstructor(JCClassDecl tree, Symbol ctor,
2588                                         Map<Symbol,Symbol> callMap) {
2589         if (ctor != null && (ctor.flags_field & ACYCLIC) == 0) {
2590             if ((ctor.flags_field & LOCKED) != 0) {
2591                 log.error(TreeInfo.diagnosticPositionFor(ctor, tree),
2592                           "recursive.ctor.invocation");
2593             } else {
2594                 ctor.flags_field |= LOCKED;
2595                 checkCyclicConstructor(tree, callMap.remove(ctor), callMap);
2596                 ctor.flags_field &= ~LOCKED;
2597             }
2598             ctor.flags_field |= ACYCLIC;
2599         }
2600     }
2601 
2602 /* *************************************************************************
2603  * Miscellaneous
2604  **************************************************************************/
2605 
2606     /**
2607      * Return the opcode of the operator but emit an error if it is an
2608      * error.
2609      * @param pos        position for error reporting.
2610      * @param operator   an operator
2611      * @param tag        a tree tag
2612      * @param left       type of left hand side
2613      * @param right      type of right hand side
2614      */
2615     int checkOperator(DiagnosticPosition pos,
2616                        OperatorSymbol operator,
2617                        int tag,
2618                        Type left,
2619                        Type right) {
2620         if (operator.opcode == ByteCodes.error) {
2621             log.error(pos,
2622                       "operator.cant.be.applied.1",
2623                       treeinfo.operatorName(tag),
2624                       left, right);
2625         }
2626         return operator.opcode;
2627     }
2628 
2629 
2630     /**
2631      *  Check for division by integer constant zero
2632      *  @param pos           Position for error reporting.
2633      *  @param operator      The operator for the expression
2634      *  @param operand       The right hand operand for the expression
2635      */
2636     void checkDivZero(DiagnosticPosition pos, Symbol operator, Type operand) {
2637         if (operand.constValue() != null
2638             && lint.isEnabled(LintCategory.DIVZERO)
2639             && operand.tag <= LONG
2640             && ((Number) (operand.constValue())).longValue() == 0) {
2641             int opc = ((OperatorSymbol)operator).opcode;
2642             if (opc == ByteCodes.idiv || opc == ByteCodes.imod
2643                 || opc == ByteCodes.ldiv || opc == ByteCodes.lmod) {
2644                 log.warning(LintCategory.DIVZERO, pos, "div.zero");
2645             }
2646         }
2647     }
2648 
2649     /**
2650      * Check for empty statements after if
2651      */
2652     void checkEmptyIf(JCIf tree) {
2653         if (tree.thenpart.getTag() == JCTree.SKIP && tree.elsepart == null && lint.isEnabled(LintCategory.EMPTY))
2654             log.warning(LintCategory.EMPTY, tree.thenpart.pos(), "empty.if");
2655     }
2656 
2657     /** Check that symbol is unique in given scope.
2658      *  @param pos           Position for error reporting.
2659      *  @param sym           The symbol.
2660      *  @param s             The scope.
2661      */
2662     boolean checkUnique(DiagnosticPosition pos, Symbol sym, Scope s) {
2663         if (sym.type.isErroneous())
2664             return true;
2665         if (sym.owner.name == names.any) return false;
2666         for (Scope.Entry e = s.lookup(sym.name); e.scope == s; e = e.next()) {
2667             if (sym != e.sym &&
2668                     (e.sym.flags() & CLASH) == 0 &&
2669                     sym.kind == e.sym.kind &&
2670                     sym.name != names.error &&
2671                     (sym.kind != MTH || types.hasSameArgs(types.erasure(sym.type), types.erasure(e.sym.type)))) {
2672                 if ((sym.flags() & VARARGS) != (e.sym.flags() & VARARGS)) {
2673                     varargsDuplicateError(pos, sym, e.sym);
2674                     return true;
2675                 } else if (sym.kind == MTH && !types.hasSameArgs(sym.type, e.sym.type, false)) {
2676                     duplicateErasureError(pos, sym, e.sym);
2677                     sym.flags_field |= CLASH;
2678                     return true;
2679                 } else {
2680                     duplicateError(pos, e.sym);
2681                     return false;
2682                 }
2683             }
2684         }
2685         return true;
2686     }
2687 
2688     /** Report duplicate declaration error.
2689      */
2690     void duplicateErasureError(DiagnosticPosition pos, Symbol sym1, Symbol sym2) {
2691         if (!sym1.type.isErroneous() && !sym2.type.isErroneous()) {
2692             log.error(pos, "name.clash.same.erasure", sym1, sym2);
2693         }
2694     }
2695 
2696     /** Check that single-type import is not already imported or top-level defined,
2697      *  but make an exception for two single-type imports which denote the same type.
2698      *  @param pos           Position for error reporting.
2699      *  @param sym           The symbol.
2700      *  @param s             The scope
2701      */
2702     boolean checkUniqueImport(DiagnosticPosition pos, Symbol sym, Scope s) {
2703         return checkUniqueImport(pos, sym, s, false);
2704     }
2705 
2706     /** Check that static single-type import is not already imported or top-level defined,
2707      *  but make an exception for two single-type imports which denote the same type.
2708      *  @param pos           Position for error reporting.
2709      *  @param sym           The symbol.
2710      *  @param s             The scope
2711      *  @param staticImport  Whether or not this was a static import
2712      */
2713     boolean checkUniqueStaticImport(DiagnosticPosition pos, Symbol sym, Scope s) {
2714         return checkUniqueImport(pos, sym, s, true);
2715     }
2716 
2717     /** Check that single-type import is not already imported or top-level defined,
2718      *  but make an exception for two single-type imports which denote the same type.
2719      *  @param pos           Position for error reporting.
2720      *  @param sym           The symbol.
2721      *  @param s             The scope.
2722      *  @param staticImport  Whether or not this was a static import
2723      */
2724     private boolean checkUniqueImport(DiagnosticPosition pos, Symbol sym, Scope s, boolean staticImport) {
2725         for (Scope.Entry e = s.lookup(sym.name); e.scope != null; e = e.next()) {
2726             // is encountered class entered via a class declaration?
2727             boolean isClassDecl = e.scope == s;
2728             if ((isClassDecl || sym != e.sym) &&
2729                 sym.kind == e.sym.kind &&
2730                 sym.name != names.error) {
2731                 if (!e.sym.type.isErroneous()) {
2732                     String what = e.sym.toString();
2733                     if (!isClassDecl) {
2734                         if (staticImport)
2735                             log.error(pos, "already.defined.static.single.import", what);
2736                         else
2737                             log.error(pos, "already.defined.single.import", what);
2738                     }
2739                     else if (sym != e.sym)
2740                         log.error(pos, "already.defined.this.unit", what);
2741                 }
2742                 return false;
2743             }
2744         }
2745         return true;
2746     }
2747 
2748     /** Check that a qualified name is in canonical form (for import decls).
2749      */
2750     public void checkCanonical(JCTree tree) {
2751         if (!isCanonical(tree))
2752             log.error(tree.pos(), "import.requires.canonical",
2753                       TreeInfo.symbol(tree));
2754     }
2755         // where
2756         private boolean isCanonical(JCTree tree) {
2757             while (tree.getTag() == JCTree.SELECT) {
2758                 JCFieldAccess s = (JCFieldAccess) tree;
2759                 if (s.sym.owner != TreeInfo.symbol(s.selected))
2760                     return false;
2761                 tree = s.selected;
2762             }
2763             return true;
2764         }
2765 
2766     private class ConversionWarner extends Warner {
2767         final String uncheckedKey;
2768         final Type found;
2769         final Type expected;
2770         public ConversionWarner(DiagnosticPosition pos, String uncheckedKey, Type found, Type expected) {
2771             super(pos);
2772             this.uncheckedKey = uncheckedKey;
2773             this.found = found;
2774             this.expected = expected;
2775         }
2776 
2777         @Override
2778         public void warn(LintCategory lint) {
2779             boolean warned = this.warned;
2780             super.warn(lint);
2781             if (warned) return; // suppress redundant diagnostics
2782             switch (lint) {
2783                 case UNCHECKED:
2784                     Check.this.warnUnchecked(pos(), "prob.found.req", diags.fragment(uncheckedKey), found, expected);
2785                     break;
2786                 case VARARGS:
2787                     if (method != null &&
2788                             method.attribute(syms.trustMeType.tsym) != null &&
2789                             isTrustMeAllowedOnMethod(method) &&
2790                             !types.isReifiable(method.type.getParameterTypes().last())) {
2791                         Check.this.warnUnsafeVararg(pos(), "varargs.unsafe.use.varargs.param", method.params.last());
2792                     }
2793                     break;
2794                 default:
2795                     throw new AssertionError("Unexpected lint: " + lint);
2796             }
2797         }
2798     }
2799 
2800     public Warner castWarner(DiagnosticPosition pos, Type found, Type expected) {
2801         return new ConversionWarner(pos, "unchecked.cast.to.type", found, expected);
2802     }
2803 
2804     public Warner convertWarner(DiagnosticPosition pos, Type found, Type expected) {
2805         return new ConversionWarner(pos, "unchecked.assign", found, expected);
2806     }
2807 }