diff -r 000000000000 -r 9a66ca7c79fa src/share/classes/com/sun/tools/javac/comp/Check.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/classes/com/sun/tools/javac/comp/Check.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,2123 @@
+/*
+ * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package com.sun.tools.javac.comp;
+
+import java.util.*;
+import java.util.Set;
+
+import com.sun.tools.javac.code.*;
+import com.sun.tools.javac.jvm.*;
+import com.sun.tools.javac.tree.*;
+import com.sun.tools.javac.util.*;
+import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
+import com.sun.tools.javac.util.List;
+
+import com.sun.tools.javac.tree.JCTree.*;
+import com.sun.tools.javac.code.Lint;
+import com.sun.tools.javac.code.Lint.LintCategory;
+import com.sun.tools.javac.code.Type.*;
+import com.sun.tools.javac.code.Symbol.*;
+
+import static com.sun.tools.javac.code.Flags.*;
+import static com.sun.tools.javac.code.Kinds.*;
+import static com.sun.tools.javac.code.TypeTags.*;
+
+/** Type checking helper class for the attribution phase.
+ *
+ *  <p><b>This is NOT part of any API supported by Sun Microsystems.  If
+ *  you write code that depends on this, you do so at your own risk.
+ *  This code and its internal interfaces are subject to change or
+ *  deletion without notice.</b>
+ */
+public class Check {
+    protected static final Context.Key<Check> checkKey =
+        new Context.Key<Check>();
+
+    private final Name.Table names;
+    private final Log log;
+    private final Symtab syms;
+    private final Infer infer;
+    private final Target target;
+    private final Source source;
+    private final Types types;
+    private final boolean skipAnnotations;
+    private final TreeInfo treeinfo;
+
+    // The set of lint options currently in effect. It is initialized
+    // from the context, and then is set/reset as needed by Attr as it
+    // visits all the various parts of the trees during attribution.
+    private Lint lint;
+
+    public static Check instance(Context context) {
+        Check instance = context.get(checkKey);
+        if (instance == null)
+            instance = new Check(context);
+        return instance;
+    }
+
+    protected Check(Context context) {
+        context.put(checkKey, this);
+
+        names = Name.Table.instance(context);
+        log = Log.instance(context);
+        syms = Symtab.instance(context);
+        infer = Infer.instance(context);
+        this.types = Types.instance(context);
+        Options options = Options.instance(context);
+        target = Target.instance(context);
+        source = Source.instance(context);
+        lint = Lint.instance(context);
+        treeinfo = TreeInfo.instance(context);
+
+        Source source = Source.instance(context);
+        allowGenerics = source.allowGenerics();
+        allowAnnotations = source.allowAnnotations();
+        complexInference = options.get("-complexinference") != null;
+        skipAnnotations = options.get("skipAnnotations") != null;
+
+        boolean verboseDeprecated = lint.isEnabled(LintCategory.DEPRECATION);
+        boolean verboseUnchecked = lint.isEnabled(LintCategory.UNCHECKED);
+
+        deprecationHandler = new MandatoryWarningHandler(log,verboseDeprecated, "deprecated");
+        uncheckedHandler = new MandatoryWarningHandler(log, verboseUnchecked, "unchecked");
+    }
+
+    /** Switch: generics enabled?
+     */
+    boolean allowGenerics;
+
+    /** Switch: annotations enabled?
+     */
+    boolean allowAnnotations;
+
+    /** Switch: -complexinference option set?
+     */
+    boolean complexInference;
+
+    /** A table mapping flat names of all compiled classes in this run to their
+     *  symbols; maintained from outside.
+     */
+    public Map<Name,ClassSymbol> compiled = new HashMap<Name, ClassSymbol>();
+
+    /** A handler for messages about deprecated usage.
+     */
+    private MandatoryWarningHandler deprecationHandler;
+
+    /** A handler for messages about unchecked or unsafe usage.
+     */
+    private MandatoryWarningHandler uncheckedHandler;
+
+
+/* *************************************************************************
+ * Errors and Warnings
+ **************************************************************************/
+
+    Lint setLint(Lint newLint) {
+        Lint prev = lint;
+        lint = newLint;
+        return prev;
+    }
+
+    /** Warn about deprecated symbol.
+     *  @param pos        Position to be used for error reporting.
+     *  @param sym        The deprecated symbol.
+     */
+    void warnDeprecated(DiagnosticPosition pos, Symbol sym) {
+        if (!lint.isSuppressed(LintCategory.DEPRECATION))
+            deprecationHandler.report(pos, "has.been.deprecated", sym, sym.location());
+    }
+
+    /** Warn about unchecked operation.
+     *  @param pos        Position to be used for error reporting.
+     *  @param msg        A string describing the problem.
+     */
+    public void warnUnchecked(DiagnosticPosition pos, String msg, Object... args) {
+        if (!lint.isSuppressed(LintCategory.UNCHECKED))
+            uncheckedHandler.report(pos, msg, args);
+    }
+
+    /**
+     * Report any deferred diagnostics.
+     */
+    public void reportDeferredDiagnostics() {
+        deprecationHandler.reportDeferredDiagnostic();
+        uncheckedHandler.reportDeferredDiagnostic();
+    }
+
+
+    /** Report a failure to complete a class.
+     *  @param pos        Position to be used for error reporting.
+     *  @param ex         The failure to report.
+     */
+    public Type completionError(DiagnosticPosition pos, CompletionFailure ex) {
+        log.error(pos, "cant.access", ex.sym, ex.errmsg);
+        if (ex instanceof ClassReader.BadClassFile) throw new Abort();
+        else return syms.errType;
+    }
+
+    /** Report a type error.
+     *  @param pos        Position to be used for error reporting.
+     *  @param problem    A string describing the error.
+     *  @param found      The type that was found.
+     *  @param req        The type that was required.
+     */
+    Type typeError(DiagnosticPosition pos, Object problem, Type found, Type req) {
+        log.error(pos, "prob.found.req",
+                  problem, found, req);
+        return syms.errType;
+    }
+
+    Type typeError(DiagnosticPosition pos, String problem, Type found, Type req, Object explanation) {
+        log.error(pos, "prob.found.req.1", problem, found, req, explanation);
+        return syms.errType;
+    }
+
+    /** Report an error that wrong type tag was found.
+     *  @param pos        Position to be used for error reporting.
+     *  @param required   An internationalized string describing the type tag
+     *                    required.
+     *  @param found      The type that was found.
+     */
+    Type typeTagError(DiagnosticPosition pos, Object required, Object found) {
+        log.error(pos, "type.found.req", found, required);
+        return syms.errType;
+    }
+
+    /** Report an error that symbol cannot be referenced before super
+     *  has been called.
+     *  @param pos        Position to be used for error reporting.
+     *  @param sym        The referenced symbol.
+     */
+    void earlyRefError(DiagnosticPosition pos, Symbol sym) {
+        log.error(pos, "cant.ref.before.ctor.called", sym);
+    }
+
+    /** Report duplicate declaration error.
+     */
+    void duplicateError(DiagnosticPosition pos, Symbol sym) {
+        if (!sym.type.isErroneous()) {
+            log.error(pos, "already.defined", sym, sym.location());
+        }
+    }
+
+    /** Report array/varargs duplicate declaration
+     */
+    void varargsDuplicateError(DiagnosticPosition pos, Symbol sym1, Symbol sym2) {
+        if (!sym1.type.isErroneous() && !sym2.type.isErroneous()) {
+            log.error(pos, "array.and.varargs", sym1, sym2, sym2.location());
+        }
+    }
+
+/* ************************************************************************
+ * duplicate declaration checking
+ *************************************************************************/
+
+    /** Check that variable does not hide variable with same name in
+     *  immediately enclosing local scope.
+     *  @param pos           Position for error reporting.
+     *  @param v             The symbol.
+     *  @param s             The scope.
+     */
+    void checkTransparentVar(DiagnosticPosition pos, VarSymbol v, Scope s) {
+        if (s.next != null) {
+            for (Scope.Entry e = s.next.lookup(v.name);
+                 e.scope != null && e.sym.owner == v.owner;
+                 e = e.next()) {
+                if (e.sym.kind == VAR &&
+                    (e.sym.owner.kind & (VAR | MTH)) != 0 &&
+                    v.name != names.error) {
+                    duplicateError(pos, e.sym);
+                    return;
+                }
+            }
+        }
+    }
+
+    /** Check that a class or interface does not hide a class or
+     *  interface with same name in immediately enclosing local scope.
+     *  @param pos           Position for error reporting.
+     *  @param c             The symbol.
+     *  @param s             The scope.
+     */
+    void checkTransparentClass(DiagnosticPosition pos, ClassSymbol c, Scope s) {
+        if (s.next != null) {
+            for (Scope.Entry e = s.next.lookup(c.name);
+                 e.scope != null && e.sym.owner == c.owner;
+                 e = e.next()) {
+                if (e.sym.kind == TYP &&
+                    (e.sym.owner.kind & (VAR | MTH)) != 0 &&
+                    c.name != names.error) {
+                    duplicateError(pos, e.sym);
+                    return;
+                }
+            }
+        }
+    }
+
+    /** Check that class does not have the same name as one of
+     *  its enclosing classes, or as a class defined in its enclosing scope.
+     *  return true if class is unique in its enclosing scope.
+     *  @param pos           Position for error reporting.
+     *  @param name          The class name.
+     *  @param s             The enclosing scope.
+     */
+    boolean checkUniqueClassName(DiagnosticPosition pos, Name name, Scope s) {
+        for (Scope.Entry e = s.lookup(name); e.scope == s; e = e.next()) {
+            if (e.sym.kind == TYP && e.sym.name != names.error) {
+                duplicateError(pos, e.sym);
+                return false;
+            }
+        }
+        for (Symbol sym = s.owner; sym != null; sym = sym.owner) {
+            if (sym.kind == TYP && sym.name == name && sym.name != names.error) {
+                duplicateError(pos, sym);
+                return true;
+            }
+        }
+        return true;
+    }
+
+/* *************************************************************************
+ * Class name generation
+ **************************************************************************/
+
+    /** Return name of local class.
+     *  This is of the form    <enclClass> $ n <classname>
+     *  where
+     *    enclClass is the flat name of the enclosing class,
+     *    classname is the simple name of the local class
+     */
+    Name localClassName(ClassSymbol c) {
+        for (int i=1; ; i++) {
+            Name flatname = names.
+                fromString("" + c.owner.enclClass().flatname +
+                           target.syntheticNameChar() + i +
+                           c.name);
+            if (compiled.get(flatname) == null) return flatname;
+        }
+    }
+
+/* *************************************************************************
+ * Type Checking
+ **************************************************************************/
+
+    /** Check that a given type is assignable to a given proto-type.
+     *  If it is, return the type, otherwise return errType.
+     *  @param pos        Position to be used for error reporting.
+     *  @param found      The type that was found.
+     *  @param req        The type that was required.
+     */
+    Type checkType(DiagnosticPosition pos, Type found, Type req) {
+        if (req.tag == ERROR)
+            return req;
+        if (found.tag == FORALL)
+            return instantiatePoly(pos, (ForAll)found, req, convertWarner(pos, found, req));
+        if (req.tag == NONE)
+            return found;
+        if (types.isAssignable(found, req, convertWarner(pos, found, req)))
+            return found;
+        if (found.tag <= DOUBLE && req.tag <= DOUBLE)
+            return typeError(pos, JCDiagnostic.fragment("possible.loss.of.precision"), found, req);
+        if (found.isSuperBound()) {
+            log.error(pos, "assignment.from.super-bound", found);
+            return syms.errType;
+        }
+        if (req.isExtendsBound()) {
+            log.error(pos, "assignment.to.extends-bound", req);
+            return syms.errType;
+        }
+        return typeError(pos, JCDiagnostic.fragment("incompatible.types"), found, req);
+    }
+
+    /** Instantiate polymorphic type to some prototype, unless
+     *  prototype is `anyPoly' in which case polymorphic type
+     *  is returned unchanged.
+     */
+    Type instantiatePoly(DiagnosticPosition pos, ForAll t, Type pt, Warner warn) {
+        if (pt == Infer.anyPoly && complexInference) {
+            return t;
+        } else if (pt == Infer.anyPoly || pt.tag == NONE) {
+            Type newpt = t.qtype.tag <= VOID ? t.qtype : syms.objectType;
+            return instantiatePoly(pos, t, newpt, warn);
+        } else if (pt.tag == ERROR) {
+            return pt;
+        } else {
+            try {
+                return infer.instantiateExpr(t, pt, warn);
+            } catch (Infer.NoInstanceException ex) {
+                if (ex.isAmbiguous) {
+                    JCDiagnostic d = ex.getDiagnostic();
+                    log.error(pos,
+                              "undetermined.type" + (d!=null ? ".1" : ""),
+                              t, d);
+                    return syms.errType;
+                } else {
+                    JCDiagnostic d = ex.getDiagnostic();
+                    return typeError(pos,
+                                     JCDiagnostic.fragment("incompatible.types" + (d!=null ? ".1" : ""), d),
+                                     t, pt);
+                }
+            }
+        }
+    }
+
+    /** Check that a given type can be cast to a given target type.
+     *  Return the result of the cast.
+     *  @param pos        Position to be used for error reporting.
+     *  @param found      The type that is being cast.
+     *  @param req        The target type of the cast.
+     */
+    Type checkCastable(DiagnosticPosition pos, Type found, Type req) {
+        if (found.tag == FORALL) {
+            instantiatePoly(pos, (ForAll) found, req, castWarner(pos, found, req));
+            return req;
+        } else if (types.isCastable(found, req, castWarner(pos, found, req))) {
+            return req;
+        } else {
+            return typeError(pos,
+                             JCDiagnostic.fragment("inconvertible.types"),
+                             found, req);
+        }
+    }
+//where
+        /** Is type a type variable, or a (possibly multi-dimensional) array of
+         *  type variables?
+         */
+        boolean isTypeVar(Type t) {
+            return t.tag == TYPEVAR || t.tag == ARRAY && isTypeVar(types.elemtype(t));
+        }
+
+    /** Check that a type is within some bounds.
+     *
+     *  Used in TypeApply to verify that, e.g., X in V<X> is a valid
+     *  type argument.
+     *  @param pos           Position to be used for error reporting.
+     *  @param a             The type that should be bounded by bs.
+     *  @param bs            The bound.
+     */
+    private void checkExtends(DiagnosticPosition pos, Type a, TypeVar bs) {
+        if (a.isUnbound()) {
+            return;
+        } else if (a.tag != WILDCARD) {
+            a = types.upperBound(a);
+            for (List<Type> l = types.getBounds(bs); l.nonEmpty(); l = l.tail) {
+                if (!types.isSubtype(a, l.head)) {
+                    log.error(pos, "not.within.bounds", a);
+                    return;
+                }
+            }
+        } else if (a.isExtendsBound()) {
+            if (!types.isCastable(bs.getUpperBound(), types.upperBound(a), Warner.noWarnings))
+                log.error(pos, "not.within.bounds", a);
+        } else if (a.isSuperBound()) {
+            if (types.notSoftSubtype(types.lowerBound(a), bs.getUpperBound()))
+                log.error(pos, "not.within.bounds", a);
+        }
+    }
+
+    /** Check that type is different from 'void'.
+     *  @param pos           Position to be used for error reporting.
+     *  @param t             The type to be checked.
+     */
+    Type checkNonVoid(DiagnosticPosition pos, Type t) {
+        if (t.tag == VOID) {
+            log.error(pos, "void.not.allowed.here");
+            return syms.errType;
+        } else {
+            return t;
+        }
+    }
+
+    /** Check that type is a class or interface type.
+     *  @param pos           Position to be used for error reporting.
+     *  @param t             The type to be checked.
+     */
+    Type checkClassType(DiagnosticPosition pos, Type t) {
+        if (t.tag != CLASS && t.tag != ERROR)
+            return typeTagError(pos,
+                                JCDiagnostic.fragment("type.req.class"),
+                                (t.tag == TYPEVAR)
+                                ? JCDiagnostic.fragment("type.parameter", t)
+                                : t);
+        else
+            return t;
+    }
+
+    /** Check that type is a class or interface type.
+     *  @param pos           Position to be used for error reporting.
+     *  @param t             The type to be checked.
+     *  @param noBounds    True if type bounds are illegal here.
+     */
+    Type checkClassType(DiagnosticPosition pos, Type t, boolean noBounds) {
+        t = checkClassType(pos, t);
+        if (noBounds && t.isParameterized()) {
+            List<Type> args = t.getTypeArguments();
+            while (args.nonEmpty()) {
+                if (args.head.tag == WILDCARD)
+                    return typeTagError(pos,
+                                        log.getLocalizedString("type.req.exact"),
+                                        args.head);
+                args = args.tail;
+            }
+        }
+        return t;
+    }
+
+    /** Check that type is a reifiable class, interface or array type.
+     *  @param pos           Position to be used for error reporting.
+     *  @param t             The type to be checked.
+     */
+    Type checkReifiableReferenceType(DiagnosticPosition pos, Type t) {
+        if (t.tag != CLASS && t.tag != ARRAY && t.tag != ERROR) {
+            return typeTagError(pos,
+                                JCDiagnostic.fragment("type.req.class.array"),
+                                t);
+        } else if (!types.isReifiable(t)) {
+            log.error(pos, "illegal.generic.type.for.instof");
+            return syms.errType;
+        } else {
+            return t;
+        }
+    }
+
+    /** Check that type is a reference type, i.e. a class, interface or array type
+     *  or a type variable.
+     *  @param pos           Position to be used for error reporting.
+     *  @param t             The type to be checked.
+     */
+    Type checkRefType(DiagnosticPosition pos, Type t) {
+        switch (t.tag) {
+        case CLASS:
+        case ARRAY:
+        case TYPEVAR:
+        case WILDCARD:
+        case ERROR:
+            return t;
+        default:
+            return typeTagError(pos,
+                                JCDiagnostic.fragment("type.req.ref"),
+                                t);
+        }
+    }
+
+    /** Check that type is a null or reference type.
+     *  @param pos           Position to be used for error reporting.
+     *  @param t             The type to be checked.
+     */
+    Type checkNullOrRefType(DiagnosticPosition pos, Type t) {
+        switch (t.tag) {
+        case CLASS:
+        case ARRAY:
+        case TYPEVAR:
+        case WILDCARD:
+        case BOT:
+        case ERROR:
+            return t;
+        default:
+            return typeTagError(pos,
+                                JCDiagnostic.fragment("type.req.ref"),
+                                t);
+        }
+    }
+
+    /** Check that flag set does not contain elements of two conflicting sets. s
+     *  Return true if it doesn't.
+     *  @param pos           Position to be used for error reporting.
+     *  @param flags         The set of flags to be checked.
+     *  @param set1          Conflicting flags set #1.
+     *  @param set2          Conflicting flags set #2.
+     */
+    boolean checkDisjoint(DiagnosticPosition pos, long flags, long set1, long set2) {
+        if ((flags & set1) != 0 && (flags & set2) != 0) {
+            log.error(pos,
+                      "illegal.combination.of.modifiers",
+                      TreeInfo.flagNames(TreeInfo.firstFlag(flags & set1)),
+                      TreeInfo.flagNames(TreeInfo.firstFlag(flags & set2)));
+            return false;
+        } else
+            return true;
+    }
+
+    /** Check that given modifiers are legal for given symbol and
+     *  return modifiers together with any implicit modififiers for that symbol.
+     *  Warning: we can't use flags() here since this method
+     *  is called during class enter, when flags() would cause a premature
+     *  completion.
+     *  @param pos           Position to be used for error reporting.
+     *  @param flags         The set of modifiers given in a definition.
+     *  @param sym           The defined symbol.
+     */
+    long checkFlags(DiagnosticPosition pos, long flags, Symbol sym, JCTree tree) {
+        long mask;
+        long implicit = 0;
+        switch (sym.kind) {
+        case VAR:
+            if (sym.owner.kind != TYP)
+                mask = LocalVarFlags;
+            else if ((sym.owner.flags_field & INTERFACE) != 0)
+                mask = implicit = InterfaceVarFlags;
+            else
+                mask = VarFlags;
+            break;
+        case MTH:
+            if (sym.name == names.init) {
+                if ((sym.owner.flags_field & ENUM) != 0) {
+                    // enum constructors cannot be declared public or
+                    // protected and must be implicitly or explicitly
+                    // private
+                    implicit = PRIVATE;
+                    mask = PRIVATE;
+                } else
+                    mask = ConstructorFlags;
+            }  else if ((sym.owner.flags_field & INTERFACE) != 0)
+                mask = implicit = InterfaceMethodFlags;
+            else {
+                mask = MethodFlags;
+            }
+            // Imply STRICTFP if owner has STRICTFP set.
+            if (((flags|implicit) & Flags.ABSTRACT) == 0)
+              implicit |= sym.owner.flags_field & STRICTFP;
+            break;
+        case TYP:
+            if (sym.isLocal()) {
+                mask = LocalClassFlags;
+                if (sym.name.len == 0) { // Anonymous class
+                    // Anonymous classes in static methods are themselves static;
+                    // that's why we admit STATIC here.
+                    mask |= STATIC;
+                    // JLS: Anonymous classes are final.
+                    implicit |= FINAL;
+                }
+                if ((sym.owner.flags_field & STATIC) == 0 &&
+                    (flags & ENUM) != 0)
+                    log.error(pos, "enums.must.be.static");
+            } else if (sym.owner.kind == TYP) {
+                mask = MemberClassFlags;
+                if (sym.owner.owner.kind == PCK ||
+                    (sym.owner.flags_field & STATIC) != 0)
+                    mask |= STATIC;
+                else if ((flags & ENUM) != 0)
+                    log.error(pos, "enums.must.be.static");
+                // Nested interfaces and enums are always STATIC (Spec ???)
+                if ((flags & (INTERFACE | ENUM)) != 0 ) implicit = STATIC;
+            } else {
+                mask = ClassFlags;
+            }
+            // Interfaces are always ABSTRACT
+            if ((flags & INTERFACE) != 0) implicit |= ABSTRACT;
+
+            if ((flags & ENUM) != 0) {
+                // enums can't be declared abstract or final
+                mask &= ~(ABSTRACT | FINAL);
+                implicit |= implicitEnumFinalFlag(tree);
+            }
+            // Imply STRICTFP if owner has STRICTFP set.
+            implicit |= sym.owner.flags_field & STRICTFP;
+            break;
+        default:
+            throw new AssertionError();
+        }
+        long illegal = flags & StandardFlags & ~mask;
+        if (illegal != 0) {
+            if ((illegal & INTERFACE) != 0) {
+                log.error(pos, "intf.not.allowed.here");
+                mask |= INTERFACE;
+            }
+            else {
+                log.error(pos,
+                          "mod.not.allowed.here", TreeInfo.flagNames(illegal));
+            }
+        }
+        else if ((sym.kind == TYP ||
+                  // ISSUE: Disallowing abstract&private is no longer appropriate
+                  // in the presence of inner classes. Should it be deleted here?
+                  checkDisjoint(pos, flags,
+                                ABSTRACT,
+                                PRIVATE | STATIC))
+                 &&
+                 checkDisjoint(pos, flags,
+                               ABSTRACT | INTERFACE,
+                               FINAL | NATIVE | SYNCHRONIZED)
+                 &&
+                 checkDisjoint(pos, flags,
+                               PUBLIC,
+                               PRIVATE | PROTECTED)
+                 &&
+                 checkDisjoint(pos, flags,
+                               PRIVATE,
+                               PUBLIC | PROTECTED)
+                 &&
+                 checkDisjoint(pos, flags,
+                               FINAL,
+                               VOLATILE)
+                 &&
+                 (sym.kind == TYP ||
+                  checkDisjoint(pos, flags,
+                                ABSTRACT | NATIVE,
+                                STRICTFP))) {
+            // skip
+        }
+        return flags & (mask | ~StandardFlags) | implicit;
+    }
+
+
+    /** Determine if this enum should be implicitly final.
+     *
+     *  If the enum has no specialized enum contants, it is final.
+     *
+     *  If the enum does have specialized enum contants, it is
+     *  <i>not</i> final.
+     */
+    private long implicitEnumFinalFlag(JCTree tree) {
+        if (tree.getTag() != JCTree.CLASSDEF) return 0;
+        class SpecialTreeVisitor extends JCTree.Visitor {
+            boolean specialized;
+            SpecialTreeVisitor() {
+                this.specialized = false;
+            };
+
+            public void visitTree(JCTree tree) { /* no-op */ }
+
+            public void visitVarDef(JCVariableDecl tree) {
+                if ((tree.mods.flags & ENUM) != 0) {
+                    if (tree.init instanceof JCNewClass &&
+                        ((JCNewClass) tree.init).def != null) {
+                        specialized = true;
+                    }
+                }
+            }
+        }
+
+        SpecialTreeVisitor sts = new SpecialTreeVisitor();
+        JCClassDecl cdef = (JCClassDecl) tree;
+        for (JCTree defs: cdef.defs) {
+            defs.accept(sts);
+            if (sts.specialized) return 0;
+        }
+        return FINAL;
+    }
+
+/* *************************************************************************
+ * Type Validation
+ **************************************************************************/
+
+    /** Validate a type expression. That is,
+     *  check that all type arguments of a parametric type are within
+     *  their bounds. This must be done in a second phase after type attributon
+     *  since a class might have a subclass as type parameter bound. E.g:
+     *
+     *  class B<A extends C> { ... }
+     *  class C extends B<C> { ... }
+     *
+     *  and we can't make sure that the bound is already attributed because
+     *  of possible cycles.
+     */
+    private Validator validator = new Validator();
+
+    /** Visitor method: Validate a type expression, if it is not null, catching
+     *  and reporting any completion failures.
+     */
+    void validate(JCTree tree) {
+        try {
+            if (tree != null) tree.accept(validator);
+        } catch (CompletionFailure ex) {
+            completionError(tree.pos(), ex);
+        }
+    }
+
+    /** Visitor method: Validate a list of type expressions.
+     */
+    void validate(List<? extends JCTree> trees) {
+        for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
+            validate(l.head);
+    }
+
+    /** Visitor method: Validate a list of type parameters.
+     */
+    void validateTypeParams(List<JCTypeParameter> trees) {
+        for (List<JCTypeParameter> l = trees; l.nonEmpty(); l = l.tail)
+            validate(l.head);
+    }
+
+    /** A visitor class for type validation.
+     */
+    class Validator extends JCTree.Visitor {
+
+        public void visitTypeArray(JCArrayTypeTree tree) {
+            validate(tree.elemtype);
+        }
+
+        public void visitTypeApply(JCTypeApply tree) {
+            if (tree.type.tag == CLASS) {
+                List<Type> formals = tree.type.tsym.type.getTypeArguments();
+                List<Type> actuals = tree.type.getTypeArguments();
+                List<JCExpression> args = tree.arguments;
+                List<Type> forms = formals;
+                ListBuffer<TypeVar> tvars_buf = new ListBuffer<TypeVar>();
+
+                // For matching pairs of actual argument types `a' and
+                // formal type parameters with declared bound `b' ...
+                while (args.nonEmpty() && forms.nonEmpty()) {
+                    validate(args.head);
+
+                    // exact type arguments needs to know their
+                    // bounds (for upper and lower bound
+                    // calculations).  So we create new TypeVars with
+                    // bounds substed with actuals.
+                    tvars_buf.append(types.substBound(((TypeVar)forms.head),
+                                                      formals,
+                                                      Type.removeBounds(actuals)));
+
+                    args = args.tail;
+                    forms = forms.tail;
+                }
+
+                args = tree.arguments;
+                List<TypeVar> tvars = tvars_buf.toList();
+                while (args.nonEmpty() && tvars.nonEmpty()) {
+                    // Let the actual arguments know their bound
+                    args.head.type.withTypeVar(tvars.head);
+                    args = args.tail;
+                    tvars = tvars.tail;
+                }
+
+                args = tree.arguments;
+                tvars = tvars_buf.toList();
+                while (args.nonEmpty() && tvars.nonEmpty()) {
+                    checkExtends(args.head.pos(),
+                                 args.head.type,
+                                 tvars.head);
+                    args = args.tail;
+                    tvars = tvars.tail;
+                }
+
+                // Check that this type is either fully parameterized, or
+                // not parameterized at all.
+                if (tree.type.getEnclosingType().isRaw())
+                    log.error(tree.pos(), "improperly.formed.type.inner.raw.param");
+                if (tree.clazz.getTag() == JCTree.SELECT)
+                    visitSelectInternal((JCFieldAccess)tree.clazz);
+            }
+        }
+
+        public void visitTypeParameter(JCTypeParameter tree) {
+            validate(tree.bounds);
+            checkClassBounds(tree.pos(), tree.type);
+        }
+
+        @Override
+        public void visitWildcard(JCWildcard tree) {
+            if (tree.inner != null)
+                validate(tree.inner);
+        }
+
+        public void visitSelect(JCFieldAccess tree) {
+            if (tree.type.tag == CLASS) {
+                visitSelectInternal(tree);
+
+                // Check that this type is either fully parameterized, or
+                // not parameterized at all.
+                if (tree.selected.type.isParameterized() && tree.type.tsym.type.getTypeArguments().nonEmpty())
+                    log.error(tree.pos(), "improperly.formed.type.param.missing");
+            }
+        }
+        public void visitSelectInternal(JCFieldAccess tree) {
+            if (tree.type.getEnclosingType().tag != CLASS &&
+                tree.selected.type.isParameterized()) {
+                // The enclosing type is not a class, so we are
+                // looking at a static member type.  However, the
+                // qualifying expression is parameterized.
+                log.error(tree.pos(), "cant.select.static.class.from.param.type");
+            } else {
+                // otherwise validate the rest of the expression
+                validate(tree.selected);
+            }
+        }
+
+        /** Default visitor method: do nothing.
+         */
+        public void visitTree(JCTree tree) {
+        }
+    }
+
+/* *************************************************************************
+ * Exception checking
+ **************************************************************************/
+
+    /* The following methods treat classes as sets that contain
+     * the class itself and all their subclasses
+     */
+
+    /** Is given type a subtype of some of the types in given list?
+     */
+    boolean subset(Type t, List<Type> ts) {
+        for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
+            if (types.isSubtype(t, l.head)) return true;
+        return false;
+    }
+
+    /** Is given type a subtype or supertype of
+     *  some of the types in given list?
+     */
+    boolean intersects(Type t, List<Type> ts) {
+        for (List<Type> l = ts; l.nonEmpty(); l = l.tail)
+            if (types.isSubtype(t, l.head) || types.isSubtype(l.head, t)) return true;
+        return false;
+    }
+
+    /** Add type set to given type list, unless it is a subclass of some class
+     *  in the list.
+     */
+    List<Type> incl(Type t, List<Type> ts) {
+        return subset(t, ts) ? ts : excl(t, ts).prepend(t);
+    }
+
+    /** Remove type set from type set list.
+     */
+    List<Type> excl(Type t, List<Type> ts) {
+        if (ts.isEmpty()) {
+            return ts;
+        } else {
+            List<Type> ts1 = excl(t, ts.tail);
+            if (types.isSubtype(ts.head, t)) return ts1;
+            else if (ts1 == ts.tail) return ts;
+            else return ts1.prepend(ts.head);
+        }
+    }
+
+    /** Form the union of two type set lists.
+     */
+    List<Type> union(List<Type> ts1, List<Type> ts2) {
+        List<Type> ts = ts1;
+        for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
+            ts = incl(l.head, ts);
+        return ts;
+    }
+
+    /** Form the difference of two type lists.
+     */
+    List<Type> diff(List<Type> ts1, List<Type> ts2) {
+        List<Type> ts = ts1;
+        for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
+            ts = excl(l.head, ts);
+        return ts;
+    }
+
+    /** Form the intersection of two type lists.
+     */
+    public List<Type> intersect(List<Type> ts1, List<Type> ts2) {
+        List<Type> ts = List.nil();
+        for (List<Type> l = ts1; l.nonEmpty(); l = l.tail)
+            if (subset(l.head, ts2)) ts = incl(l.head, ts);
+        for (List<Type> l = ts2; l.nonEmpty(); l = l.tail)
+            if (subset(l.head, ts1)) ts = incl(l.head, ts);
+        return ts;
+    }
+
+    /** Is exc an exception symbol that need not be declared?
+     */
+    boolean isUnchecked(ClassSymbol exc) {
+        return
+            exc.kind == ERR ||
+            exc.isSubClass(syms.errorType.tsym, types) ||
+            exc.isSubClass(syms.runtimeExceptionType.tsym, types);
+    }
+
+    /** Is exc an exception type that need not be declared?
+     */
+    boolean isUnchecked(Type exc) {
+        return
+            (exc.tag == TYPEVAR) ? isUnchecked(types.supertype(exc)) :
+            (exc.tag == CLASS) ? isUnchecked((ClassSymbol)exc.tsym) :
+            exc.tag == BOT;
+    }
+
+    /** Same, but handling completion failures.
+     */
+    boolean isUnchecked(DiagnosticPosition pos, Type exc) {
+        try {
+            return isUnchecked(exc);
+        } catch (CompletionFailure ex) {
+            completionError(pos, ex);
+            return true;
+        }
+    }
+
+    /** Is exc handled by given exception list?
+     */
+    boolean isHandled(Type exc, List<Type> handled) {
+        return isUnchecked(exc) || subset(exc, handled);
+    }
+
+    /** Return all exceptions in thrown list that are not in handled list.
+     *  @param thrown     The list of thrown exceptions.
+     *  @param handled    The list of handled exceptions.
+     */
+    List<Type> unHandled(List<Type> thrown, List<Type> handled) {
+        List<Type> unhandled = List.nil();
+        for (List<Type> l = thrown; l.nonEmpty(); l = l.tail)
+            if (!isHandled(l.head, handled)) unhandled = unhandled.prepend(l.head);
+        return unhandled;
+    }
+
+/* *************************************************************************
+ * Overriding/Implementation checking
+ **************************************************************************/
+
+    /** The level of access protection given by a flag set,
+     *  where PRIVATE is highest and PUBLIC is lowest.
+     */
+    static int protection(long flags) {
+        switch ((short)(flags & AccessFlags)) {
+        case PRIVATE: return 3;
+        case PROTECTED: return 1;
+        default:
+        case PUBLIC: return 0;
+        case 0: return 2;
+        }
+    }
+
+    /** A string describing the access permission given by a flag set.
+     *  This always returns a space-separated list of Java Keywords.
+     */
+    private static String protectionString(long flags) {
+        long flags1 = flags & AccessFlags;
+        return (flags1 == 0) ? "package" : TreeInfo.flagNames(flags1);
+    }
+
+    /** A customized "cannot override" error message.
+     *  @param m      The overriding method.
+     *  @param other  The overridden method.
+     *  @return       An internationalized string.
+     */
+    static Object cannotOverride(MethodSymbol m, MethodSymbol other) {
+        String key;
+        if ((other.owner.flags() & INTERFACE) == 0)
+            key = "cant.override";
+        else if ((m.owner.flags() & INTERFACE) == 0)
+            key = "cant.implement";
+        else
+            key = "clashes.with";
+        return JCDiagnostic.fragment(key, m, m.location(), other, other.location());
+    }
+
+    /** A customized "override" warning message.
+     *  @param m      The overriding method.
+     *  @param other  The overridden method.
+     *  @return       An internationalized string.
+     */
+    static Object uncheckedOverrides(MethodSymbol m, MethodSymbol other) {
+        String key;
+        if ((other.owner.flags() & INTERFACE) == 0)
+            key = "unchecked.override";
+        else if ((m.owner.flags() & INTERFACE) == 0)
+            key = "unchecked.implement";
+        else
+            key = "unchecked.clash.with";
+        return JCDiagnostic.fragment(key, m, m.location(), other, other.location());
+    }
+
+    /** A customized "override" warning message.
+     *  @param m      The overriding method.
+     *  @param other  The overridden method.
+     *  @return       An internationalized string.
+     */
+    static Object varargsOverrides(MethodSymbol m, MethodSymbol other) {
+        String key;
+        if ((other.owner.flags() & INTERFACE) == 0)
+            key = "varargs.override";
+        else  if ((m.owner.flags() & INTERFACE) == 0)
+            key = "varargs.implement";
+        else
+            key = "varargs.clash.with";
+        return JCDiagnostic.fragment(key, m, m.location(), other, other.location());
+    }
+
+    /** Check that this method conforms with overridden method 'other'.
+     *  where `origin' is the class where checking started.
+     *  Complications:
+     *  (1) Do not check overriding of synthetic methods
+     *      (reason: they might be final).
+     *      todo: check whether this is still necessary.
+     *  (2) Admit the case where an interface proxy throws fewer exceptions
+     *      than the method it implements. Augment the proxy methods with the
+     *      undeclared exceptions in this case.
+     *  (3) When generics are enabled, admit the case where an interface proxy
+     *      has a result type
+     *      extended by the result type of the method it implements.
+     *      Change the proxies result type to the smaller type in this case.
+     *
+     *  @param tree         The tree from which positions
+     *                      are extracted for errors.
+     *  @param m            The overriding method.
+     *  @param other        The overridden method.
+     *  @param origin       The class of which the overriding method
+     *                      is a member.
+     */
+    void checkOverride(JCTree tree,
+                       MethodSymbol m,
+                       MethodSymbol other,
+                       ClassSymbol origin) {
+        // Don't check overriding of synthetic methods or by bridge methods.
+        if ((m.flags() & (SYNTHETIC|BRIDGE)) != 0 || (other.flags() & SYNTHETIC) != 0) {
+            return;
+        }
+
+        // Error if static method overrides instance method (JLS 8.4.6.2).
+        if ((m.flags() & STATIC) != 0 &&
+                   (other.flags() & STATIC) == 0) {
+            log.error(TreeInfo.diagnosticPositionFor(m, tree), "override.static",
+                      cannotOverride(m, other));
+            return;
+        }
+
+        // Error if instance method overrides static or final
+        // method (JLS 8.4.6.1).
+        if ((other.flags() & FINAL) != 0 ||
+                 (m.flags() & STATIC) == 0 &&
+                 (other.flags() & STATIC) != 0) {
+            log.error(TreeInfo.diagnosticPositionFor(m, tree), "override.meth",
+                      cannotOverride(m, other),
+                      TreeInfo.flagNames(other.flags() & (FINAL | STATIC)));
+            return;
+        }
+
+        if ((m.owner.flags() & ANNOTATION) != 0) {
+            // handled in validateAnnotationMethod
+            return;
+        }
+
+        // Error if overriding method has weaker access (JLS 8.4.6.3).
+        if ((origin.flags() & INTERFACE) == 0 &&
+                 protection(m.flags()) > protection(other.flags())) {
+            log.error(TreeInfo.diagnosticPositionFor(m, tree), "override.weaker.access",
+                      cannotOverride(m, other),
+                      protectionString(other.flags()));
+            return;
+
+        }
+
+        Type mt = types.memberType(origin.type, m);
+        Type ot = types.memberType(origin.type, other);
+        // Error if overriding result type is different
+        // (or, in the case of generics mode, not a subtype) of
+        // overridden result type. We have to rename any type parameters
+        // before comparing types.
+        List<Type> mtvars = mt.getTypeArguments();
+        List<Type> otvars = ot.getTypeArguments();
+        Type mtres = mt.getReturnType();
+        Type otres = types.subst(ot.getReturnType(), otvars, mtvars);
+
+        overrideWarner.warned = false;
+        boolean resultTypesOK =
+            types.returnTypeSubstitutable(mt, ot, otres, overrideWarner);
+        if (!resultTypesOK) {
+            if (!source.allowCovariantReturns() &&
+                m.owner != origin &&
+                m.owner.isSubClass(other.owner, types)) {
+                // allow limited interoperability with covariant returns
+            } else {
+                typeError(TreeInfo.diagnosticPositionFor(m, tree),
+                          JCDiagnostic.fragment("override.incompatible.ret",
+                                         cannotOverride(m, other)),
+                          mtres, otres);
+                return;
+            }
+        } else if (overrideWarner.warned) {
+            warnUnchecked(TreeInfo.diagnosticPositionFor(m, tree),
+                          "prob.found.req",
+                          JCDiagnostic.fragment("override.unchecked.ret",
+                                              uncheckedOverrides(m, other)),
+                          mtres, otres);
+        }
+
+        // Error if overriding method throws an exception not reported
+        // by overridden method.
+        List<Type> otthrown = types.subst(ot.getThrownTypes(), otvars, mtvars);
+        List<Type> unhandled = unHandled(mt.getThrownTypes(), otthrown);
+        if (unhandled.nonEmpty()) {
+            log.error(TreeInfo.diagnosticPositionFor(m, tree),
+                      "override.meth.doesnt.throw",
+                      cannotOverride(m, other),
+                      unhandled.head);
+            return;
+        }
+
+        // Optional warning if varargs don't agree
+        if ((((m.flags() ^ other.flags()) & Flags.VARARGS) != 0)
+            && lint.isEnabled(Lint.LintCategory.OVERRIDES)) {
+            log.warning(TreeInfo.diagnosticPositionFor(m, tree),
+                        ((m.flags() & Flags.VARARGS) != 0)
+                        ? "override.varargs.missing"
+                        : "override.varargs.extra",
+                        varargsOverrides(m, other));
+        }
+
+        // Warn if instance method overrides bridge method (compiler spec ??)
+        if ((other.flags() & BRIDGE) != 0) {
+            log.warning(TreeInfo.diagnosticPositionFor(m, tree), "override.bridge",
+                        uncheckedOverrides(m, other));
+        }
+
+        // Warn if a deprecated method overridden by a non-deprecated one.
+        if ((other.flags() & DEPRECATED) != 0
+            && (m.flags() & DEPRECATED) == 0
+            && m.outermostClass() != other.outermostClass()
+            && !isDeprecatedOverrideIgnorable(other, origin)) {
+            warnDeprecated(TreeInfo.diagnosticPositionFor(m, tree), other);
+        }
+    }
+    // where
+        private boolean isDeprecatedOverrideIgnorable(MethodSymbol m, ClassSymbol origin) {
+            // If the method, m, is defined in an interface, then ignore the issue if the method
+            // is only inherited via a supertype and also implemented in the supertype,
+            // because in that case, we will rediscover the issue when examining the method
+            // in the supertype.
+            // If the method, m, is not defined in an interface, then the only time we need to
+            // address the issue is when the method is the supertype implemementation: any other
+            // case, we will have dealt with when examining the supertype classes
+            ClassSymbol mc = m.enclClass();
+            Type st = types.supertype(origin.type);
+            if (st.tag != CLASS)
+                return true;
+            MethodSymbol stimpl = m.implementation((ClassSymbol)st.tsym, types, false);
+
+            if (mc != null && ((mc.flags() & INTERFACE) != 0)) {
+                List<Type> intfs = types.interfaces(origin.type);
+                return (intfs.contains(mc.type) ? false : (stimpl != null));
+            }
+            else
+                return (stimpl != m);
+        }
+
+
+    // used to check if there were any unchecked conversions
+    Warner overrideWarner = new Warner();
+
+    /** Check that a class does not inherit two concrete methods
+     *  with the same signature.
+     *  @param pos          Position to be used for error reporting.
+     *  @param site         The class type to be checked.
+     */
+    public void checkCompatibleConcretes(DiagnosticPosition pos, Type site) {
+        Type sup = types.supertype(site);
+        if (sup.tag != CLASS) return;
+
+        for (Type t1 = sup;
+             t1.tsym.type.isParameterized();
+             t1 = types.supertype(t1)) {
+            for (Scope.Entry e1 = t1.tsym.members().elems;
+                 e1 != null;
+                 e1 = e1.sibling) {
+                Symbol s1 = e1.sym;
+                if (s1.kind != MTH ||
+                    (s1.flags() & (STATIC|SYNTHETIC|BRIDGE)) != 0 ||
+                    !s1.isInheritedIn(site.tsym, types) ||
+                    ((MethodSymbol)s1).implementation(site.tsym,
+                                                      types,
+                                                      true) != s1)
+                    continue;
+                Type st1 = types.memberType(t1, s1);
+                int s1ArgsLength = st1.getParameterTypes().length();
+                if (st1 == s1.type) continue;
+
+                for (Type t2 = sup;
+                     t2.tag == CLASS;
+                     t2 = types.supertype(t2)) {
+                    for (Scope.Entry e2 = t1.tsym.members().lookup(s1.name);
+                         e2.scope != null;
+                         e2 = e2.next()) {
+                        Symbol s2 = e2.sym;
+                        if (s2 == s1 ||
+                            s2.kind != MTH ||
+                            (s2.flags() & (STATIC|SYNTHETIC|BRIDGE)) != 0 ||
+                            s2.type.getParameterTypes().length() != s1ArgsLength ||
+                            !s2.isInheritedIn(site.tsym, types) ||
+                            ((MethodSymbol)s2).implementation(site.tsym,
+                                                              types,
+                                                              true) != s2)
+                            continue;
+                        Type st2 = types.memberType(t2, s2);
+                        if (types.overrideEquivalent(st1, st2))
+                            log.error(pos, "concrete.inheritance.conflict",
+                                      s1, t1, s2, t2, sup);
+                    }
+                }
+            }
+        }
+    }
+
+    /** Check that classes (or interfaces) do not each define an abstract
+     *  method with same name and arguments but incompatible return types.
+     *  @param pos          Position to be used for error reporting.
+     *  @param t1           The first argument type.
+     *  @param t2           The second argument type.
+     */
+    public boolean checkCompatibleAbstracts(DiagnosticPosition pos,
+                                            Type t1,
+                                            Type t2) {
+        return checkCompatibleAbstracts(pos, t1, t2,
+                                        types.makeCompoundType(t1, t2));
+    }
+
+    public boolean checkCompatibleAbstracts(DiagnosticPosition pos,
+                                            Type t1,
+                                            Type t2,
+                                            Type site) {
+        Symbol sym = firstIncompatibility(t1, t2, site);
+        if (sym != null) {
+            log.error(pos, "types.incompatible.diff.ret",
+                      t1, t2, sym.name +
+                      "(" + types.memberType(t2, sym).getParameterTypes() + ")");
+            return false;
+        }
+        return true;
+    }
+
+    /** Return the first method which is defined with same args
+     *  but different return types in two given interfaces, or null if none
+     *  exists.
+     *  @param t1     The first type.
+     *  @param t2     The second type.
+     *  @param site   The most derived type.
+     *  @returns symbol from t2 that conflicts with one in t1.
+     */
+    private Symbol firstIncompatibility(Type t1, Type t2, Type site) {
+        Map<TypeSymbol,Type> interfaces1 = new HashMap<TypeSymbol,Type>();
+        closure(t1, interfaces1);
+        Map<TypeSymbol,Type> interfaces2;
+        if (t1 == t2)
+            interfaces2 = interfaces1;
+        else
+            closure(t2, interfaces1, interfaces2 = new HashMap<TypeSymbol,Type>());
+
+        for (Type t3 : interfaces1.values()) {
+            for (Type t4 : interfaces2.values()) {
+                Symbol s = firstDirectIncompatibility(t3, t4, site);
+                if (s != null) return s;
+            }
+        }
+        return null;
+    }
+
+    /** Compute all the supertypes of t, indexed by type symbol. */
+    private void closure(Type t, Map<TypeSymbol,Type> typeMap) {
+        if (t.tag != CLASS) return;
+        if (typeMap.put(t.tsym, t) == null) {
+            closure(types.supertype(t), typeMap);
+            for (Type i : types.interfaces(t))
+                closure(i, typeMap);
+        }
+    }
+
+    /** Compute all the supertypes of t, indexed by type symbol (except thise in typesSkip). */
+    private void closure(Type t, Map<TypeSymbol,Type> typesSkip, Map<TypeSymbol,Type> typeMap) {
+        if (t.tag != CLASS) return;
+        if (typesSkip.get(t.tsym) != null) return;
+        if (typeMap.put(t.tsym, t) == null) {
+            closure(types.supertype(t), typesSkip, typeMap);
+            for (Type i : types.interfaces(t))
+                closure(i, typesSkip, typeMap);
+        }
+    }
+
+    /** Return the first method in t2 that conflicts with a method from t1. */
+    private Symbol firstDirectIncompatibility(Type t1, Type t2, Type site) {
+        for (Scope.Entry e1 = t1.tsym.members().elems; e1 != null; e1 = e1.sibling) {
+            Symbol s1 = e1.sym;
+            Type st1 = null;
+            if (s1.kind != MTH || !s1.isInheritedIn(site.tsym, types)) continue;
+            Symbol impl = ((MethodSymbol)s1).implementation(site.tsym, types, false);
+            if (impl != null && (impl.flags() & ABSTRACT) == 0) continue;
+            for (Scope.Entry e2 = t2.tsym.members().lookup(s1.name); e2.scope != null; e2 = e2.next()) {
+                Symbol s2 = e2.sym;
+                if (s1 == s2) continue;
+                if (s2.kind != MTH || !s2.isInheritedIn(site.tsym, types)) continue;
+                if (st1 == null) st1 = types.memberType(t1, s1);
+                Type st2 = types.memberType(t2, s2);
+                if (types.overrideEquivalent(st1, st2)) {
+                    List<Type> tvars1 = st1.getTypeArguments();
+                    List<Type> tvars2 = st2.getTypeArguments();
+                    Type rt1 = st1.getReturnType();
+                    Type rt2 = types.subst(st2.getReturnType(), tvars2, tvars1);
+                    boolean compat =
+                        types.isSameType(rt1, rt2) ||
+                        rt1.tag >= CLASS && rt2.tag >= CLASS &&
+                        (types.covariantReturnType(rt1, rt2, Warner.noWarnings) ||
+                         types.covariantReturnType(rt2, rt1, Warner.noWarnings));
+                    if (!compat) return s2;
+                }
+            }
+        }
+        return null;
+    }
+
+    /** Check that a given method conforms with any method it overrides.
+     *  @param tree         The tree from which positions are extracted
+     *                      for errors.
+     *  @param m            The overriding method.
+     */
+    void checkOverride(JCTree tree, MethodSymbol m) {
+        ClassSymbol origin = (ClassSymbol)m.owner;
+        if ((origin.flags() & ENUM) != 0 && names.finalize.equals(m.name))
+            if (m.overrides(syms.enumFinalFinalize, origin, types, false)) {
+                log.error(tree.pos(), "enum.no.finalize");
+                return;
+            }
+        for (Type t = types.supertype(origin.type); t.tag == CLASS;
+             t = types.supertype(t)) {
+            TypeSymbol c = t.tsym;
+            Scope.Entry e = c.members().lookup(m.name);
+            while (e.scope != null) {
+                if (m.overrides(e.sym, origin, types, false))
+                    checkOverride(tree, m, (MethodSymbol)e.sym, origin);
+                e = e.next();
+            }
+        }
+    }
+
+    /** Check that all abstract members of given class have definitions.
+     *  @param pos          Position to be used for error reporting.
+     *  @param c            The class.
+     */
+    void checkAllDefined(DiagnosticPosition pos, ClassSymbol c) {
+        try {
+            MethodSymbol undef = firstUndef(c, c);
+            if (undef != null) {
+                if ((c.flags() & ENUM) != 0 &&
+                    types.supertype(c.type).tsym == syms.enumSym &&
+                    (c.flags() & FINAL) == 0) {
+                    // add the ABSTRACT flag to an enum
+                    c.flags_field |= ABSTRACT;
+                } else {
+                    MethodSymbol undef1 =
+                        new MethodSymbol(undef.flags(), undef.name,
+                                         types.memberType(c.type, undef), undef.owner);
+                    log.error(pos, "does.not.override.abstract",
+                              c, undef1, undef1.location());
+                }
+            }
+        } catch (CompletionFailure ex) {
+            completionError(pos, ex);
+        }
+    }
+//where
+        /** Return first abstract member of class `c' that is not defined
+         *  in `impl', null if there is none.
+         */
+        private MethodSymbol firstUndef(ClassSymbol impl, ClassSymbol c) {
+            MethodSymbol undef = null;
+            // Do not bother to search in classes that are not abstract,
+            // since they cannot have abstract members.
+            if (c == impl || (c.flags() & (ABSTRACT | INTERFACE)) != 0) {
+                Scope s = c.members();
+                for (Scope.Entry e = s.elems;
+                     undef == null && e != null;
+                     e = e.sibling) {
+                    if (e.sym.kind == MTH &&
+                        (e.sym.flags() & (ABSTRACT|IPROXY)) == ABSTRACT) {
+                        MethodSymbol absmeth = (MethodSymbol)e.sym;
+                        MethodSymbol implmeth = absmeth.implementation(impl, types, true);
+                        if (implmeth == null || implmeth == absmeth)
+                            undef = absmeth;
+                    }
+                }
+                if (undef == null) {
+                    Type st = types.supertype(c.type);
+                    if (st.tag == CLASS)
+                        undef = firstUndef(impl, (ClassSymbol)st.tsym);
+                }
+                for (List<Type> l = types.interfaces(c.type);
+                     undef == null && l.nonEmpty();
+                     l = l.tail) {
+                    undef = firstUndef(impl, (ClassSymbol)l.head.tsym);
+                }
+            }
+            return undef;
+        }
+
+    /** Check for cyclic references. Issue an error if the
+     *  symbol of the type referred to has a LOCKED flag set.
+     *
+     *  @param pos      Position to be used for error reporting.
+     *  @param t        The type referred to.
+     */
+    void checkNonCyclic(DiagnosticPosition pos, Type t) {
+        checkNonCyclicInternal(pos, t);
+    }
+
+
+    void checkNonCyclic(DiagnosticPosition pos, TypeVar t) {
+        checkNonCyclic1(pos, t, new HashSet<TypeVar>());
+    }
+
+    private void checkNonCyclic1(DiagnosticPosition pos, Type t, Set<TypeVar> seen) {
+        final TypeVar tv;
+        if (seen.contains(t)) {
+            tv = (TypeVar)t;
+            tv.bound = new ErrorType();
+            log.error(pos, "cyclic.inheritance", t);
+        } else if (t.tag == TYPEVAR) {
+            tv = (TypeVar)t;
+            seen.add(tv);
+            for (Type b : types.getBounds(tv))
+                checkNonCyclic1(pos, b, seen);
+        }
+    }
+
+    /** Check for cyclic references. Issue an error if the
+     *  symbol of the type referred to has a LOCKED flag set.
+     *
+     *  @param pos      Position to be used for error reporting.
+     *  @param t        The type referred to.
+     *  @returns        True if the check completed on all attributed classes
+     */
+    private boolean checkNonCyclicInternal(DiagnosticPosition pos, Type t) {
+        boolean complete = true; // was the check complete?
+        //- System.err.println("checkNonCyclicInternal("+t+");");//DEBUG
+        Symbol c = t.tsym;
+        if ((c.flags_field & ACYCLIC) != 0) return true;
+
+        if ((c.flags_field & LOCKED) != 0) {
+            noteCyclic(pos, (ClassSymbol)c);
+        } else if (!c.type.isErroneous()) {
+            try {
+                c.flags_field |= LOCKED;
+                if (c.type.tag == CLASS) {
+                    ClassType clazz = (ClassType)c.type;
+                    if (clazz.interfaces_field != null)
+                        for (List<Type> l=clazz.interfaces_field; l.nonEmpty(); l=l.tail)
+                            complete &= checkNonCyclicInternal(pos, l.head);
+                    if (clazz.supertype_field != null) {
+                        Type st = clazz.supertype_field;
+                        if (st != null && st.tag == CLASS)
+                            complete &= checkNonCyclicInternal(pos, st);
+                    }
+                    if (c.owner.kind == TYP)
+                        complete &= checkNonCyclicInternal(pos, c.owner.type);
+                }
+            } finally {
+                c.flags_field &= ~LOCKED;
+            }
+        }
+        if (complete)
+            complete = ((c.flags_field & UNATTRIBUTED) == 0) && c.completer == null;
+        if (complete) c.flags_field |= ACYCLIC;
+        return complete;
+    }
+
+    /** Note that we found an inheritance cycle. */
+    private void noteCyclic(DiagnosticPosition pos, ClassSymbol c) {
+        log.error(pos, "cyclic.inheritance", c);
+        for (List<Type> l=types.interfaces(c.type); l.nonEmpty(); l=l.tail)
+            l.head = new ErrorType((ClassSymbol)l.head.tsym);
+        Type st = types.supertype(c.type);
+        if (st.tag == CLASS)
+            ((ClassType)c.type).supertype_field = new ErrorType((ClassSymbol)st.tsym);
+        c.type = new ErrorType(c);
+        c.flags_field |= ACYCLIC;
+    }
+
+    /** Check that all methods which implement some
+     *  method conform to the method they implement.
+     *  @param tree         The class definition whose members are checked.
+     */
+    void checkImplementations(JCClassDecl tree) {
+        checkImplementations(tree, tree.sym);
+    }
+//where
+        /** Check that all methods which implement some
+         *  method in `ic' conform to the method they implement.
+         */
+        void checkImplementations(JCClassDecl tree, ClassSymbol ic) {
+            ClassSymbol origin = tree.sym;
+            for (List<Type> l = types.closure(ic.type); l.nonEmpty(); l = l.tail) {
+                ClassSymbol lc = (ClassSymbol)l.head.tsym;
+                if ((allowGenerics || origin != lc) && (lc.flags() & ABSTRACT) != 0) {
+                    for (Scope.Entry e=lc.members().elems; e != null; e=e.sibling) {
+                        if (e.sym.kind == MTH &&
+                            (e.sym.flags() & (STATIC|ABSTRACT)) == ABSTRACT) {
+                            MethodSymbol absmeth = (MethodSymbol)e.sym;
+                            MethodSymbol implmeth = absmeth.implementation(origin, types, false);
+                            if (implmeth != null && implmeth != absmeth &&
+                                (implmeth.owner.flags() & INTERFACE) ==
+                                (origin.flags() & INTERFACE)) {
+                                // don't check if implmeth is in a class, yet
+                                // origin is an interface. This case arises only
+                                // if implmeth is declared in Object. The reason is
+                                // that interfaces really don't inherit from
+                                // Object it's just that the compiler represents
+                                // things that way.
+                                checkOverride(tree, implmeth, absmeth, origin);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+    /** Check that all abstract methods implemented by a class are
+     *  mutually compatible.
+     *  @param pos          Position to be used for error reporting.
+     *  @param c            The class whose interfaces are checked.
+     */
+    void checkCompatibleSupertypes(DiagnosticPosition pos, Type c) {
+        List<Type> supertypes = types.interfaces(c);
+        Type supertype = types.supertype(c);
+        if (supertype.tag == CLASS &&
+            (supertype.tsym.flags() & ABSTRACT) != 0)
+            supertypes = supertypes.prepend(supertype);
+        for (List<Type> l = supertypes; l.nonEmpty(); l = l.tail) {
+            if (allowGenerics && !l.head.getTypeArguments().isEmpty() &&
+                !checkCompatibleAbstracts(pos, l.head, l.head, c))
+                return;
+            for (List<Type> m = supertypes; m != l; m = m.tail)
+                if (!checkCompatibleAbstracts(pos, l.head, m.head, c))
+                    return;
+        }
+        checkCompatibleConcretes(pos, c);
+    }
+
+    /** Check that class c does not implement directly or indirectly
+     *  the same parameterized interface with two different argument lists.
+     *  @param pos          Position to be used for error reporting.
+     *  @param type         The type whose interfaces are checked.
+     */
+    void checkClassBounds(DiagnosticPosition pos, Type type) {
+        checkClassBounds(pos, new HashMap<TypeSymbol,Type>(), type);
+    }
+//where
+        /** Enter all interfaces of type `type' into the hash table `seensofar'
+         *  with their class symbol as key and their type as value. Make
+         *  sure no class is entered with two different types.
+         */
+        void checkClassBounds(DiagnosticPosition pos,
+                              Map<TypeSymbol,Type> seensofar,
+                              Type type) {
+            if (type.isErroneous()) return;
+            for (List<Type> l = types.interfaces(type); l.nonEmpty(); l = l.tail) {
+                Type it = l.head;
+                Type oldit = seensofar.put(it.tsym, it);
+                if (oldit != null) {
+                    List<Type> oldparams = oldit.allparams();
+                    List<Type> newparams = it.allparams();
+                    if (!types.containsTypeEquivalent(oldparams, newparams))
+                        log.error(pos, "cant.inherit.diff.arg",
+                                  it.tsym, Type.toString(oldparams),
+                                  Type.toString(newparams));
+                }
+                checkClassBounds(pos, seensofar, it);
+            }
+            Type st = types.supertype(type);
+            if (st != null) checkClassBounds(pos, seensofar, st);
+        }
+
+    /** Enter interface into into set.
+     *  If it existed already, issue a "repeated interface" error.
+     */
+    void checkNotRepeated(DiagnosticPosition pos, Type it, Set<Type> its) {
+        if (its.contains(it))
+            log.error(pos, "repeated.interface");
+        else {
+            its.add(it);
+        }
+    }
+
+/* *************************************************************************
+ * Check annotations
+ **************************************************************************/
+
+    /** Annotation types are restricted to primitives, String, an
+     *  enum, an annotation, Class, Class<?>, Class<? extends
+     *  Anything>, arrays of the preceding.
+     */
+    void validateAnnotationType(JCTree restype) {
+        // restype may be null if an error occurred, so don't bother validating it
+        if (restype != null) {
+            validateAnnotationType(restype.pos(), restype.type);
+        }
+    }
+
+    void validateAnnotationType(DiagnosticPosition pos, Type type) {
+        if (type.isPrimitive()) return;
+        if (types.isSameType(type, syms.stringType)) return;
+        if ((type.tsym.flags() & Flags.ENUM) != 0) return;
+        if ((type.tsym.flags() & Flags.ANNOTATION) != 0) return;
+        if (types.lowerBound(type).tsym == syms.classType.tsym) return;
+        if (types.isArray(type) && !types.isArray(types.elemtype(type))) {
+            validateAnnotationType(pos, types.elemtype(type));
+            return;
+        }
+        log.error(pos, "invalid.annotation.member.type");
+    }
+
+    /**
+     * "It is also a compile-time error if any method declared in an
+     * annotation type has a signature that is override-equivalent to
+     * that of any public or protected method declared in class Object
+     * or in the interface annotation.Annotation."
+     *
+     * @jls3 9.6 Annotation Types
+     */
+    void validateAnnotationMethod(DiagnosticPosition pos, MethodSymbol m) {
+        for (Type sup = syms.annotationType; sup.tag == CLASS; sup = types.supertype(sup)) {
+            Scope s = sup.tsym.members();
+            for (Scope.Entry e = s.lookup(m.name); e.scope != null; e = e.next()) {
+                if (e.sym.kind == MTH &&
+                    (e.sym.flags() & (PUBLIC | PROTECTED)) != 0 &&
+                    types.overrideEquivalent(m.type, e.sym.type))
+                    log.error(pos, "intf.annotation.member.clash", e.sym, sup);
+            }
+        }
+    }
+
+    /** Check the annotations of a symbol.
+     */
+    public void validateAnnotations(List<JCAnnotation> annotations, Symbol s) {
+        if (skipAnnotations) return;
+        for (JCAnnotation a : annotations)
+            validateAnnotation(a, s);
+    }
+
+    /** Check an annotation of a symbol.
+     */
+    public void validateAnnotation(JCAnnotation a, Symbol s) {
+        validateAnnotation(a);
+
+        if (!annotationApplicable(a, s))
+            log.error(a.pos(), "annotation.type.not.applicable");
+
+        if (a.annotationType.type.tsym == syms.overrideType.tsym) {
+            if (!isOverrider(s))
+                log.error(a.pos(), "method.does.not.override.superclass");
+        }
+    }
+
+    /** Is s a method symbol that overrides a method in a superclass? */
+    boolean isOverrider(Symbol s) {
+        if (s.kind != MTH || s.isStatic())
+            return false;
+        MethodSymbol m = (MethodSymbol)s;
+        TypeSymbol owner = (TypeSymbol)m.owner;
+        for (Type sup : types.closure(owner.type)) {
+            if (sup == owner.type)
+                continue; // skip "this"
+            Scope scope = sup.tsym.members();
+            for (Scope.Entry e = scope.lookup(m.name); e.scope != null; e = e.next()) {
+                if (!e.sym.isStatic() && m.overrides(e.sym, owner, types, true))
+                    return true;
+            }
+        }
+        return false;
+    }
+
+    /** Is the annotation applicable to the symbol? */
+    boolean annotationApplicable(JCAnnotation a, Symbol s) {
+        Attribute.Compound atTarget =
+            a.annotationType.type.tsym.attribute(syms.annotationTargetType.tsym);
+        if (atTarget == null) return true;
+        Attribute atValue = atTarget.member(names.value);
+        if (!(atValue instanceof Attribute.Array)) return true; // error recovery
+        Attribute.Array arr = (Attribute.Array) atValue;
+        for (Attribute app : arr.values) {
+            if (!(app instanceof Attribute.Enum)) return true; // recovery
+            Attribute.Enum e = (Attribute.Enum) app;
+            if (e.value.name == names.TYPE)
+                { if (s.kind == TYP) return true; }
+            else if (e.value.name == names.FIELD)
+                { if (s.kind == VAR && s.owner.kind != MTH) return true; }
+            else if (e.value.name == names.METHOD)
+                { if (s.kind == MTH && !s.isConstructor()) return true; }
+            else if (e.value.name == names.PARAMETER)
+                { if (s.kind == VAR &&
+                      s.owner.kind == MTH &&
+                      (s.flags() & PARAMETER) != 0)
+                    return true;
+                }
+            else if (e.value.name == names.CONSTRUCTOR)
+                { if (s.kind == MTH && s.isConstructor()) return true; }
+            else if (e.value.name == names.LOCAL_VARIABLE)
+                { if (s.kind == VAR && s.owner.kind == MTH &&
+                      (s.flags() & PARAMETER) == 0)
+                    return true;
+                }
+            else if (e.value.name == names.ANNOTATION_TYPE)
+                { if (s.kind == TYP && (s.flags() & ANNOTATION) != 0)
+                    return true;
+                }
+            else if (e.value.name == names.PACKAGE)
+                { if (s.kind == PCK) return true; }
+            else
+                return true; // recovery
+        }
+        return false;
+    }
+
+    /** Check an annotation value.
+     */
+    public void validateAnnotation(JCAnnotation a) {
+        if (a.type.isErroneous()) return;
+
+        // collect an inventory of the members
+        Set<MethodSymbol> members = new HashSet<MethodSymbol>();
+        for (Scope.Entry e = a.annotationType.type.tsym.members().elems;
+             e != null;
+             e = e.sibling)
+            if (e.sym.kind == MTH)
+                members.add((MethodSymbol) e.sym);
+
+        // count them off as they're annotated
+        for (JCTree arg : a.args) {
+            if (arg.getTag() != JCTree.ASSIGN) continue; // recovery
+            JCAssign assign = (JCAssign) arg;
+            Symbol m = TreeInfo.symbol(assign.lhs);
+            if (m == null || m.type.isErroneous()) continue;
+            if (!members.remove(m))
+                log.error(arg.pos(), "duplicate.annotation.member.value",
+                          m.name, a.type);
+            if (assign.rhs.getTag() == ANNOTATION)
+                validateAnnotation((JCAnnotation)assign.rhs);
+        }
+
+        // all the remaining ones better have default values
+        for (MethodSymbol m : members)
+            if (m.defaultValue == null && !m.type.isErroneous())
+                log.error(a.pos(), "annotation.missing.default.value",
+                          a.type, m.name);
+
+        // special case: java.lang.annotation.Target must not have
+        // repeated values in its value member
+        if (a.annotationType.type.tsym != syms.annotationTargetType.tsym ||
+            a.args.tail == null)
+            return;
+
+        if (a.args.head.getTag() != JCTree.ASSIGN) return; // error recovery
+        JCAssign assign = (JCAssign) a.args.head;
+        Symbol m = TreeInfo.symbol(assign.lhs);
+        if (m.name != names.value) return;
+        JCTree rhs = assign.rhs;
+        if (rhs.getTag() != JCTree.NEWARRAY) return;
+        JCNewArray na = (JCNewArray) rhs;
+        Set<Symbol> targets = new HashSet<Symbol>();
+        for (JCTree elem : na.elems) {
+            if (!targets.add(TreeInfo.symbol(elem))) {
+                log.error(elem.pos(), "repeated.annotation.target");
+            }
+        }
+    }
+
+    void checkDeprecatedAnnotation(DiagnosticPosition pos, Symbol s) {
+        if (allowAnnotations &&
+            lint.isEnabled(Lint.LintCategory.DEP_ANN) &&
+            (s.flags() & DEPRECATED) != 0 &&
+            !syms.deprecatedType.isErroneous() &&
+            s.attribute(syms.deprecatedType.tsym) == null) {
+            log.warning(pos, "missing.deprecated.annotation");
+        }
+    }
+
+/* *************************************************************************
+ * Check for recursive annotation elements.
+ **************************************************************************/
+
+    /** Check for cycles in the graph of annotation elements.
+     */
+    void checkNonCyclicElements(JCClassDecl tree) {
+        if ((tree.sym.flags_field & ANNOTATION) == 0) return;
+        assert (tree.sym.flags_field & LOCKED) == 0;
+        try {
+            tree.sym.flags_field |= LOCKED;
+            for (JCTree def : tree.defs) {
+                if (def.getTag() != JCTree.METHODDEF) continue;
+                JCMethodDecl meth = (JCMethodDecl)def;
+                checkAnnotationResType(meth.pos(), meth.restype.type);
+            }
+        } finally {
+            tree.sym.flags_field &= ~LOCKED;
+            tree.sym.flags_field |= ACYCLIC_ANN;
+        }
+    }
+
+    void checkNonCyclicElementsInternal(DiagnosticPosition pos, TypeSymbol tsym) {
+        if ((tsym.flags_field & ACYCLIC_ANN) != 0)
+            return;
+        if ((tsym.flags_field & LOCKED) != 0) {
+            log.error(pos, "cyclic.annotation.element");
+            return;
+        }
+        try {
+            tsym.flags_field |= LOCKED;
+            for (Scope.Entry e = tsym.members().elems; e != null; e = e.sibling) {
+                Symbol s = e.sym;
+                if (s.kind != Kinds.MTH)
+                    continue;
+                checkAnnotationResType(pos, ((MethodSymbol)s).type.getReturnType());
+            }
+        } finally {
+            tsym.flags_field &= ~LOCKED;
+            tsym.flags_field |= ACYCLIC_ANN;
+        }
+    }
+
+    void checkAnnotationResType(DiagnosticPosition pos, Type type) {
+        switch (type.tag) {
+        case TypeTags.CLASS:
+            if ((type.tsym.flags() & ANNOTATION) != 0)
+                checkNonCyclicElementsInternal(pos, type.tsym);
+            break;
+        case TypeTags.ARRAY:
+            checkAnnotationResType(pos, types.elemtype(type));
+            break;
+        default:
+            break; // int etc
+        }
+    }
+
+/* *************************************************************************
+ * Check for cycles in the constructor call graph.
+ **************************************************************************/
+
+    /** Check for cycles in the graph of constructors calling other
+     *  constructors.
+     */
+    void checkCyclicConstructors(JCClassDecl tree) {
+        Map<Symbol,Symbol> callMap = new HashMap<Symbol, Symbol>();
+
+        // enter each constructor this-call into the map
+        for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
+            JCMethodInvocation app = TreeInfo.firstConstructorCall(l.head);
+            if (app == null) continue;
+            JCMethodDecl meth = (JCMethodDecl) l.head;
+            if (TreeInfo.name(app.meth) == names._this) {
+                callMap.put(meth.sym, TreeInfo.symbol(app.meth));
+            } else {
+                meth.sym.flags_field |= ACYCLIC;
+            }
+        }
+
+        // Check for cycles in the map
+        Symbol[] ctors = new Symbol[0];
+        ctors = callMap.keySet().toArray(ctors);
+        for (Symbol caller : ctors) {
+            checkCyclicConstructor(tree, caller, callMap);
+        }
+    }
+
+    /** Look in the map to see if the given constructor is part of a
+     *  call cycle.
+     */
+    private void checkCyclicConstructor(JCClassDecl tree, Symbol ctor,
+                                        Map<Symbol,Symbol> callMap) {
+        if (ctor != null && (ctor.flags_field & ACYCLIC) == 0) {
+            if ((ctor.flags_field & LOCKED) != 0) {
+                log.error(TreeInfo.diagnosticPositionFor(ctor, tree),
+                          "recursive.ctor.invocation");
+            } else {
+                ctor.flags_field |= LOCKED;
+                checkCyclicConstructor(tree, callMap.remove(ctor), callMap);
+                ctor.flags_field &= ~LOCKED;
+            }
+            ctor.flags_field |= ACYCLIC;
+        }
+    }
+
+/* *************************************************************************
+ * Miscellaneous
+ **************************************************************************/
+
+    /**
+     * Return the opcode of the operator but emit an error if it is an
+     * error.
+     * @param pos        position for error reporting.
+     * @param operator   an operator
+     * @param tag        a tree tag
+     * @param left       type of left hand side
+     * @param right      type of right hand side
+     */
+    int checkOperator(DiagnosticPosition pos,
+                       OperatorSymbol operator,
+                       int tag,
+                       Type left,
+                       Type right) {
+        if (operator.opcode == ByteCodes.error) {
+            log.error(pos,
+                      "operator.cant.be.applied",
+                      treeinfo.operatorName(tag),
+                      left + "," + right);
+        }
+        return operator.opcode;
+    }
+
+
+    /**
+     *  Check for division by integer constant zero
+     *  @param pos           Position for error reporting.
+     *  @param operator      The operator for the expression
+     *  @param operand       The right hand operand for the expression
+     */
+    void checkDivZero(DiagnosticPosition pos, Symbol operator, Type operand) {
+        if (operand.constValue() != null
+            && lint.isEnabled(Lint.LintCategory.DIVZERO)
+            && operand.tag <= LONG
+            && ((Number) (operand.constValue())).longValue() == 0) {
+            int opc = ((OperatorSymbol)operator).opcode;
+            if (opc == ByteCodes.idiv || opc == ByteCodes.imod
+                || opc == ByteCodes.ldiv || opc == ByteCodes.lmod) {
+                log.warning(pos, "div.zero");
+            }
+        }
+    }
+
+    /**
+     * Check for empty statements after if
+     */
+    void checkEmptyIf(JCIf tree) {
+        if (tree.thenpart.getTag() == JCTree.SKIP && tree.elsepart == null && lint.isEnabled(Lint.LintCategory.EMPTY))
+            log.warning(tree.thenpart.pos(), "empty.if");
+    }
+
+    /** Check that symbol is unique in given scope.
+     *  @param pos           Position for error reporting.
+     *  @param sym           The symbol.
+     *  @param s             The scope.
+     */
+    boolean checkUnique(DiagnosticPosition pos, Symbol sym, Scope s) {
+        if (sym.type.isErroneous())
+            return true;
+        if (sym.owner.name == names.any) return false;
+        for (Scope.Entry e = s.lookup(sym.name); e.scope == s; e = e.next()) {
+            if (sym != e.sym &&
+                sym.kind == e.sym.kind &&
+                sym.name != names.error &&
+                (sym.kind != MTH || types.overrideEquivalent(sym.type, e.sym.type))) {
+                if ((sym.flags() & VARARGS) != (e.sym.flags() & VARARGS))
+                    varargsDuplicateError(pos, sym, e.sym);
+                else
+                    duplicateError(pos, e.sym);
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /** Check that single-type import is not already imported or top-level defined,
+     *  but make an exception for two single-type imports which denote the same type.
+     *  @param pos           Position for error reporting.
+     *  @param sym           The symbol.
+     *  @param s             The scope
+     */
+    boolean checkUniqueImport(DiagnosticPosition pos, Symbol sym, Scope s) {
+        return checkUniqueImport(pos, sym, s, false);
+    }
+
+    /** Check that static single-type import is not already imported or top-level defined,
+     *  but make an exception for two single-type imports which denote the same type.
+     *  @param pos           Position for error reporting.
+     *  @param sym           The symbol.
+     *  @param s             The scope
+     *  @param staticImport  Whether or not this was a static import
+     */
+    boolean checkUniqueStaticImport(DiagnosticPosition pos, Symbol sym, Scope s) {
+        return checkUniqueImport(pos, sym, s, true);
+    }
+
+    /** Check that single-type import is not already imported or top-level defined,
+     *  but make an exception for two single-type imports which denote the same type.
+     *  @param pos           Position for error reporting.
+     *  @param sym           The symbol.
+     *  @param s             The scope.
+     *  @param staticImport  Whether or not this was a static import
+     */
+    private boolean checkUniqueImport(DiagnosticPosition pos, Symbol sym, Scope s, boolean staticImport) {
+        for (Scope.Entry e = s.lookup(sym.name); e.scope != null; e = e.next()) {
+            // is encountered class entered via a class declaration?
+            boolean isClassDecl = e.scope == s;
+            if ((isClassDecl || sym != e.sym) &&
+                sym.kind == e.sym.kind &&
+                sym.name != names.error) {
+                if (!e.sym.type.isErroneous()) {
+                    String what = e.sym.toString();
+                    if (!isClassDecl) {
+                        if (staticImport)
+                            log.error(pos, "already.defined.static.single.import", what);
+                        else
+                            log.error(pos, "already.defined.single.import", what);
+                    }
+                    else if (sym != e.sym)
+                        log.error(pos, "already.defined.this.unit", what);
+                }
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /** Check that a qualified name is in canonical form (for import decls).
+     */
+    public void checkCanonical(JCTree tree) {
+        if (!isCanonical(tree))
+            log.error(tree.pos(), "import.requires.canonical",
+                      TreeInfo.symbol(tree));
+    }
+        // where
+        private boolean isCanonical(JCTree tree) {
+            while (tree.getTag() == JCTree.SELECT) {
+                JCFieldAccess s = (JCFieldAccess) tree;
+                if (s.sym.owner != TreeInfo.symbol(s.selected))
+                    return false;
+                tree = s.selected;
+            }
+            return true;
+        }
+
+    private class ConversionWarner extends Warner {
+        final String key;
+        final Type found;
+        final Type expected;
+        public ConversionWarner(DiagnosticPosition pos, String key, Type found, Type expected) {
+            super(pos);
+            this.key = key;
+            this.found = found;
+            this.expected = expected;
+        }
+
+        public void warnUnchecked() {
+            boolean warned = this.warned;
+            super.warnUnchecked();
+            if (warned) return; // suppress redundant diagnostics
+            Object problem = JCDiagnostic.fragment(key);
+            Check.this.warnUnchecked(pos(), "prob.found.req", problem, found, expected);
+        }
+    }
+
+    public Warner castWarner(DiagnosticPosition pos, Type found, Type expected) {
+        return new ConversionWarner(pos, "unchecked.cast.to.type", found, expected);
+    }
+
+    public Warner convertWarner(DiagnosticPosition pos, Type found, Type expected) {
+        return new ConversionWarner(pos, "unchecked.assign", found, expected);
+    }
+}