Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 1999, 2012, Oracle and/or its affiliates. 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.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  */

 package com.sun.tools.javac.comp;

 import java.util.*;

 import java.util.Set;

 import javax.lang.model.element.ElementKind;

 import javax.tools.JavaFileObject;

 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.jvm.Target;

 import com.sun.tools.javac.code.Lint.LintCategory;

 import com.sun.tools.javac.code.Symbol.*;

 import com.sun.tools.javac.tree.JCTree.*;

 import com.sun.tools.javac.code.Type.*;

 import com.sun.tools.javac.comp.Check.CheckContext;

 import com.sun.source.tree.IdentifierTree;

 import com.sun.source.tree.MemberSelectTree;

 import com.sun.source.tree.TreeVisitor;

 import com.sun.source.util.SimpleTreeVisitor;

 import static com.sun.tools.javac.code.Flags.*;

 import static com.sun.tools.javac.code.Flags.ANNOTATION;

 import static com.sun.tools.javac.code.Flags.BLOCK;

 import static com.sun.tools.javac.code.Kinds.*;

 import static com.sun.tools.javac.code.Kinds.ERRONEOUS;

 import static com.sun.tools.javac.code.TypeTags.*;

 import static com.sun.tools.javac.code.TypeTags.WILDCARD;

 import static com.sun.tools.javac.tree.JCTree.Tag.*;

 /** This is the main context-dependent analysis phase in GJC. It

  *  encompasses name resolution, type checking and constant folding as

  *  subtasks. Some subtasks involve auxiliary classes.

  *  @see Check

  *  @see Resolve

  *  @see ConstFold

  *  @see Infer

  *

  *  <p><b>This is NOT part of any supported API.

  *  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 Attr extends JCTree.Visitor {

     protected static final Context.Key<Attr> attrKey =

         new Context.Key<Attr>();

     final Names names;

     final Log log;

     final Symtab syms;

     final Resolve rs;

     final Infer infer;

     final Check chk;

     final MemberEnter memberEnter;

     final TreeMaker make;

     final ConstFold cfolder;

     final Enter enter;

     final Target target;

     final Types types;

     final JCDiagnostic.Factory diags;

     final Annotate annotate;

     final DeferredLintHandler deferredLintHandler;

     public static Attr instance(Context context) {

         Attr instance = context.get(attrKey);

         if (instance == null)

             instance = new Attr(context);

         return instance;

     }

     protected Attr(Context context) {

         context.put(attrKey, this);

         names = Names.instance(context);

         log = Log.instance(context);

         syms = Symtab.instance(context);

         rs = Resolve.instance(context);

         chk = Check.instance(context);

         memberEnter = MemberEnter.instance(context);

         make = TreeMaker.instance(context);

         enter = Enter.instance(context);

         infer = Infer.instance(context);

         cfolder = ConstFold.instance(context);

         target = Target.instance(context);

         types = Types.instance(context);

         diags = JCDiagnostic.Factory.instance(context);

         annotate = Annotate.instance(context);

         deferredLintHandler = DeferredLintHandler.instance(context);

         Options options = Options.instance(context);

         Source source = Source.instance(context);

         allowGenerics = source.allowGenerics();

         allowVarargs = source.allowVarargs();

         allowEnums = source.allowEnums();

         allowBoxing = source.allowBoxing();

         allowCovariantReturns = source.allowCovariantReturns();

         allowAnonOuterThis = source.allowAnonOuterThis();

         allowStringsInSwitch = source.allowStringsInSwitch();

         sourceName = source.name;

         relax = (options.isSet("-retrofit") ||

                  options.isSet("-relax"));

         findDiamonds = options.get("findDiamond") != null &&

                  source.allowDiamond();

         useBeforeDeclarationWarning = options.isSet("useBeforeDeclarationWarning");

         statInfo = new ResultInfo(NIL, Type.noType);

         varInfo = new ResultInfo(VAR, Type.noType);

         unknownExprInfo = new ResultInfo(VAL, Type.noType);

         unknownTypeInfo = new ResultInfo(TYP, Type.noType);

     }

     /** Switch: relax some constraints for retrofit mode.

      */

     boolean relax;

     /** Switch: support generics?

      */

     boolean allowGenerics;

     /** Switch: allow variable-arity methods.

      */

     boolean allowVarargs;

     /** Switch: support enums?

      */

     boolean allowEnums;

     /** Switch: support boxing and unboxing?

      */

     boolean allowBoxing;

     /** Switch: support covariant result types?

      */

     boolean allowCovariantReturns;

     /** Switch: allow references to surrounding object from anonymous

      * objects during constructor call?

      */

     boolean allowAnonOuterThis;

     /** Switch: generates a warning if diamond can be safely applied

      *  to a given new expression

      */

     boolean findDiamonds;

     /**

      * Internally enables/disables diamond finder feature

      */

     static final boolean allowDiamondFinder = true;

     /**

      * Switch: warn about use of variable before declaration?

      * RFE: 6425594

      */

     boolean useBeforeDeclarationWarning;

     /**

      * Switch: allow strings in switch?

      */

     boolean allowStringsInSwitch;

     /**

      * Switch: name of source level; used for error reporting.

      */

     String sourceName;

     /** Check kind and type of given tree against protokind and prototype.

      *  If check succeeds, store type in tree and return it.

      *  If check fails, store errType in tree and return it.

      *  No checks are performed if the prototype is a method type.

      *  It is not necessary in this case since we know that kind and type

      *  are correct.

      *

      *  @param tree     The tree whose kind and type is checked

      *  @param owntype  The computed type of the tree

      *  @param ownkind  The computed kind of the tree

      *  @param resultInfo  The expected result of the tree

      */

     Type check(JCTree tree, Type owntype, int ownkind, ResultInfo resultInfo) {

         if (owntype.tag != ERROR && resultInfo.pt.tag != METHOD && resultInfo.pt.tag != FORALL) {

             if ((ownkind & ~resultInfo.pkind) == 0) {

                 owntype = resultInfo.check(tree, owntype);

             } else {

                 log.error(tree.pos(), "unexpected.type",

                           kindNames(resultInfo.pkind),

                           kindName(ownkind));

                 owntype = types.createErrorType(owntype);

             }

         }

         tree.type = owntype;

         return owntype;

     }

     /** Is given blank final variable assignable, i.e. in a scope where it

      *  may be assigned to even though it is final?

      *  @param v      The blank final variable.

      *  @param env    The current environment.

      */

     boolean isAssignableAsBlankFinal(VarSymbol v, Env<AttrContext> env) {

         Symbol owner = owner(env);

            // owner refers to the innermost variable, method or

            // initializer block declaration at this point.

         return

             v.owner == owner

             ||

             ((owner.name == names.init ||    // i.e. we are in a constructor

               owner.kind == VAR ||           // i.e. we are in a variable initializer

               (owner.flags() & BLOCK) != 0)  // i.e. we are in an initializer block

              &&

              v.owner == owner.owner

              &&

              ((v.flags() & STATIC) != 0) == Resolve.isStatic(env));

     }

     /**

      * Return the innermost enclosing owner symbol in a given attribution context

      */

     Symbol owner(Env<AttrContext> env) {

         while (true) {

             switch (env.tree.getTag()) {

                 case VARDEF:

                     //a field can be owner

                     VarSymbol vsym = ((JCVariableDecl)env.tree).sym;

                     if (vsym.owner.kind == TYP) {

                         return vsym;

                     }

                     break;

                 case METHODDEF:

                     //method def is always an owner

                     return ((JCMethodDecl)env.tree).sym;

                 case CLASSDEF:

                     //class def is always an owner

                     return ((JCClassDecl)env.tree).sym;

                 case BLOCK:

                     //static/instance init blocks are owner

                     Symbol blockSym = env.info.scope.owner;

                     if ((blockSym.flags() & BLOCK) != 0) {

                         return blockSym;

                     }

                     break;

                 case TOPLEVEL:

                     //toplevel is always an owner (for pkge decls)

                     return env.info.scope.owner;

             }

             Assert.checkNonNull(env.next);

             env = env.next;

         }

     }

     /** Check that variable can be assigned to.

      *  @param pos    The current source code position.

      *  @param v      The assigned varaible

      *  @param base   If the variable is referred to in a Select, the part

      *                to the left of the `.', null otherwise.

      *  @param env    The current environment.

      */

     void checkAssignable(DiagnosticPosition pos, VarSymbol v, JCTree base, Env<AttrContext> env) {

         if ((v.flags() & FINAL) != 0 &&

             ((v.flags() & HASINIT) != 0

              ||

              !((base == null ||

                (base.hasTag(IDENT) && TreeInfo.name(base) == names._this)) &&

                isAssignableAsBlankFinal(v, env)))) {

             if (v.isResourceVariable()) { //TWR resource

                 log.error(pos, "try.resource.may.not.be.assigned", v);

             } else {

                 log.error(pos, "cant.assign.val.to.final.var", v);

             }

         } else if ((v.flags() & EFFECTIVELY_FINAL) != 0) {

             v.flags_field &= ~EFFECTIVELY_FINAL;

         }

     }

     /** Does tree represent a static reference to an identifier?

      *  It is assumed that tree is either a SELECT or an IDENT.

      *  We have to weed out selects from non-type names here.

      *  @param tree    The candidate tree.

      */

     boolean isStaticReference(JCTree tree) {

         if (tree.hasTag(SELECT)) {

             Symbol lsym = TreeInfo.symbol(((JCFieldAccess) tree).selected);

             if (lsym == null || lsym.kind != TYP) {

                 return false;

             }

         }

         return true;

     }

     /** Is this symbol a type?

      */

     static boolean isType(Symbol sym) {

         return sym != null && sym.kind == TYP;

     }

     /** The current `this' symbol.

      *  @param env    The current environment.

      */

     Symbol thisSym(DiagnosticPosition pos, Env<AttrContext> env) {

         return rs.resolveSelf(pos, env, env.enclClass.sym, names._this);

     }

     /** Attribute a parsed identifier.

      * @param tree Parsed identifier name

      * @param topLevel The toplevel to use

      */

     public Symbol attribIdent(JCTree tree, JCCompilationUnit topLevel) {

         Env<AttrContext> localEnv = enter.topLevelEnv(topLevel);

         localEnv.enclClass = make.ClassDef(make.Modifiers(0),

                                            syms.errSymbol.name,

                                            null, null, null, null);

         localEnv.enclClass.sym = syms.errSymbol;

         return tree.accept(identAttributer, localEnv);

     }

     // where

         private TreeVisitor<Symbol,Env<AttrContext>> identAttributer = new IdentAttributer();

         private class IdentAttributer extends SimpleTreeVisitor<Symbol,Env<AttrContext>> {

             @Override

             public Symbol visitMemberSelect(MemberSelectTree node, Env<AttrContext> env) {

                 Symbol site = visit(node.getExpression(), env);

                 if (site.kind == ERR)

                     return site;

                 Name name = (Name)node.getIdentifier();

                 if (site.kind == PCK) {

                     env.toplevel.packge = (PackageSymbol)site;

                     return rs.findIdentInPackage(env, (TypeSymbol)site, name, TYP | PCK);

                 } else {

                     env.enclClass.sym = (ClassSymbol)site;

                     return rs.findMemberType(env, site.asType(), name, (TypeSymbol)site);

                 }

             }

             @Override

             public Symbol visitIdentifier(IdentifierTree node, Env<AttrContext> env) {

                 return rs.findIdent(env, (Name)node.getName(), TYP | PCK);

             }

         }

     public Type coerce(Type etype, Type ttype) {

         return cfolder.coerce(etype, ttype);

     }

     public Type attribType(JCTree node, TypeSymbol sym) {

         Env<AttrContext> env = enter.typeEnvs.get(sym);

         Env<AttrContext> localEnv = env.dup(node, env.info.dup());

         return attribTree(node, localEnv, unknownTypeInfo);

     }

     public Type attribImportQualifier(JCImport tree, Env<AttrContext> env) {

         // Attribute qualifying package or class.

         JCFieldAccess s = (JCFieldAccess)tree.qualid;

         return attribTree(s.selected,

                        env,

                        new ResultInfo(tree.staticImport ? TYP : (TYP | PCK),

                        Type.noType));

     }

     public Env<AttrContext> attribExprToTree(JCTree expr, Env<AttrContext> env, JCTree tree) {

         breakTree = tree;

         JavaFileObject prev = log.useSource(env.toplevel.sourcefile);

         try {

             attribExpr(expr, env);

         } catch (BreakAttr b) {

             return b.env;

         } catch (AssertionError ae) {

             if (ae.getCause() instanceof BreakAttr) {

                 return ((BreakAttr)(ae.getCause())).env;

             } else {

                 throw ae;

             }

         } finally {

             breakTree = null;

             log.useSource(prev);

         }

         return env;

     }

     public Env<AttrContext> attribStatToTree(JCTree stmt, Env<AttrContext> env, JCTree tree) {

         breakTree = tree;

         JavaFileObject prev = log.useSource(env.toplevel.sourcefile);

         try {

             attribStat(stmt, env);

         } catch (BreakAttr b) {

             return b.env;

         } catch (AssertionError ae) {

             if (ae.getCause() instanceof BreakAttr) {

                 return ((BreakAttr)(ae.getCause())).env;

             } else {

                 throw ae;

             }

         } finally {

             breakTree = null;

             log.useSource(prev);

         }

         return env;

     }

     private JCTree breakTree = null;

     private static class BreakAttr extends RuntimeException {

         static final long serialVersionUID = -6924771130405446405L;

         private Env<AttrContext> env;

         private BreakAttr(Env<AttrContext> env) {

             this.env = env;

         }

     }

     class ResultInfo {

         int pkind;

         Type pt;

         CheckContext checkContext;

         ResultInfo(int pkind, Type pt) {

             this(pkind, pt, chk.basicHandler);

         }

         protected ResultInfo(int pkind, Type pt, CheckContext checkContext) {

             this.pkind = pkind;

             this.pt = pt;

             this.checkContext = checkContext;

         }

         protected Type check(DiagnosticPosition pos, Type found) {

             return chk.checkType(pos, found, pt, checkContext);

         }

     }

     private final ResultInfo statInfo;

     private final ResultInfo varInfo;

     private final ResultInfo unknownExprInfo;

     private final ResultInfo unknownTypeInfo;

     Type pt() {

         return resultInfo.pt;

     }

     int pkind() {

         return resultInfo.pkind;

     }

 /* ************************************************************************

  * Visitor methods

  *************************************************************************/

     /** Visitor argument: the current environment.

      */

     Env<AttrContext> env;

     /** Visitor argument: the currently expected attribution result.

      */

     ResultInfo resultInfo;

     /** Visitor result: the computed type.

      */

     Type result;

     /** Visitor method: attribute a tree, catching any completion failure

      *  exceptions. Return the tree's type.

      *

      *  @param tree    The tree to be visited.

      *  @param env     The environment visitor argument.

      *  @param resultInfo   The result info visitor argument.

      */

     private Type attribTree(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo) {

         Env<AttrContext> prevEnv = this.env;

         ResultInfo prevResult = this.resultInfo;

         try {

             this.env = env;

             this.resultInfo = resultInfo;

             tree.accept(this);

             if (tree == breakTree)

                 throw new BreakAttr(env);

             return result;

         } catch (CompletionFailure ex) {

             tree.type = syms.errType;

             return chk.completionError(tree.pos(), ex);

         } finally {

             this.env = prevEnv;

             this.resultInfo = prevResult;

         }

     }

     /** Derived visitor method: attribute an expression tree.

      */

     public Type attribExpr(JCTree tree, Env<AttrContext> env, Type pt) {

         return attribTree(tree, env, new ResultInfo(VAL, pt.tag != ERROR ? pt : Type.noType));

     }

     /** Derived visitor method: attribute an expression tree with

      *  no constraints on the computed type.

      */

     Type attribExpr(JCTree tree, Env<AttrContext> env) {

         return attribTree(tree, env, unknownExprInfo);

     }

     /** Derived visitor method: attribute a type tree.

      */

     Type attribType(JCTree tree, Env<AttrContext> env) {

         Type result = attribType(tree, env, Type.noType);

         return result;

     }

     /** Derived visitor method: attribute a type tree.

      */

     Type attribType(JCTree tree, Env<AttrContext> env, Type pt) {

         Type result = attribTree(tree, env, new ResultInfo(TYP, pt));

         return result;

     }

     /** Derived visitor method: attribute a statement or definition tree.

      */

     public Type attribStat(JCTree tree, Env<AttrContext> env) {

         return attribTree(tree, env, statInfo);

     }

     /** Attribute a list of expressions, returning a list of types.

      */

     List<Type> attribExprs(List<JCExpression> trees, Env<AttrContext> env, Type pt) {

         ListBuffer<Type> ts = new ListBuffer<Type>();

         for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail)

             ts.append(attribExpr(l.head, env, pt));

         return ts.toList();

     }

     /** Attribute a list of statements, returning nothing.

      */

     <T extends JCTree> void attribStats(List<T> trees, Env<AttrContext> env) {

         for (List<T> l = trees; l.nonEmpty(); l = l.tail)

             attribStat(l.head, env);

     }

     /** Attribute the arguments in a method call, returning a list of types.

      */

     List<Type> attribArgs(List<JCExpression> trees, Env<AttrContext> env) {

         ListBuffer<Type> argtypes = new ListBuffer<Type>();

         for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail)

             argtypes.append(chk.checkNonVoid(

                 l.head.pos(), types.upperBound(attribExpr(l.head, env, Infer.anyPoly))));

         return argtypes.toList();

     }

     /** Attribute a type argument list, returning a list of types.

      *  Caller is responsible for calling checkRefTypes.

      */

     List<Type> attribAnyTypes(List<JCExpression> trees, Env<AttrContext> env) {

         ListBuffer<Type> argtypes = new ListBuffer<Type>();

         for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail)

             argtypes.append(attribType(l.head, env));

         return argtypes.toList();

     }

     /** Attribute a type argument list, returning a list of types.

      *  Check that all the types are references.

      */

     List<Type> attribTypes(List<JCExpression> trees, Env<AttrContext> env) {

         List<Type> types = attribAnyTypes(trees, env);

         return chk.checkRefTypes(trees, types);

     }

     /**

      * Attribute type variables (of generic classes or methods).

      * Compound types are attributed later in attribBounds.

      * @param typarams the type variables to enter

      * @param env      the current environment

      */

     void attribTypeVariables(List<JCTypeParameter> typarams, Env<AttrContext> env) {

         for (JCTypeParameter tvar : typarams) {

             TypeVar a = (TypeVar)tvar.type;

             a.tsym.flags_field |= UNATTRIBUTED;

             a.bound = Type.noType;

             if (!tvar.bounds.isEmpty()) {

                 List<Type> bounds = List.of(attribType(tvar.bounds.head, env));

                 for (JCExpression bound : tvar.bounds.tail)

                     bounds = bounds.prepend(attribType(bound, env));

                 types.setBounds(a, bounds.reverse());

             } else {

                 // if no bounds are given, assume a single bound of

                 // java.lang.Object.

                 types.setBounds(a, List.of(syms.objectType));

             }

             a.tsym.flags_field &= ~UNATTRIBUTED;

         }

         for (JCTypeParameter tvar : typarams)

             chk.checkNonCyclic(tvar.pos(), (TypeVar)tvar.type);

         attribStats(typarams, env);

     }

     void attribBounds(List<JCTypeParameter> typarams) {

         for (JCTypeParameter typaram : typarams) {

             Type bound = typaram.type.getUpperBound();

             if (bound != null && bound.tsym instanceof ClassSymbol) {

                 ClassSymbol c = (ClassSymbol)bound.tsym;

                 if ((c.flags_field & COMPOUND) != 0) {

                     Assert.check((c.flags_field & UNATTRIBUTED) != 0, c);

                     attribClass(typaram.pos(), c);

                 }

             }

         }

     }

     /**

      * Attribute the type references in a list of annotations.

      */

     void attribAnnotationTypes(List<JCAnnotation> annotations,

                                Env<AttrContext> env) {

         for (List<JCAnnotation> al = annotations; al.nonEmpty(); al = al.tail) {

             JCAnnotation a = al.head;

             attribType(a.annotationType, env);

         }

     }

     /**

      * Attribute a "lazy constant value".

      *  @param env         The env for the const value

      *  @param initializer The initializer for the const value

      *  @param type        The expected type, or null

      *  @see VarSymbol#setlazyConstValue

      */

     public Object attribLazyConstantValue(Env<AttrContext> env,

                                       JCTree.JCExpression initializer,

                                       Type type) {

         // in case no lint value has been set up for this env, scan up

         // env stack looking for smallest enclosing env for which it is set.

         Env<AttrContext> lintEnv = env;

         while (lintEnv.info.lint == null)

             lintEnv = lintEnv.next;

         // Having found the enclosing lint value, we can initialize the lint value for this class

         // ... but ...

         // There's a problem with evaluating annotations in the right order, such that

         // env.info.enclVar.attributes_field might not yet have been evaluated, and so might be

         // null. In that case, calling augment will throw an NPE. To avoid this, for now we

         // revert to the jdk 6 behavior and ignore the (unevaluated) attributes.

         if (env.info.enclVar.attributes_field == null)

             env.info.lint = lintEnv.info.lint;

         else

             env.info.lint = lintEnv.info.lint.augment(env.info.enclVar.attributes_field, env.info.enclVar.flags());

         Lint prevLint = chk.setLint(env.info.lint);

         JavaFileObject prevSource = log.useSource(env.toplevel.sourcefile);

         try {

             Type itype = attribExpr(initializer, env, type);

             if (itype.constValue() != null)

                 return coerce(itype, type).constValue();

             else

                 return null;

         } finally {

             env.info.lint = prevLint;

             log.useSource(prevSource);

         }

     }

     /** Attribute type reference in an `extends' or `implements' clause.

      *  Supertypes of anonymous inner classes are usually already attributed.

      *

      *  @param tree              The tree making up the type reference.

      *  @param env               The environment current at the reference.

      *  @param classExpected     true if only a class is expected here.

      *  @param interfaceExpected true if only an interface is expected here.

      */

     Type attribBase(JCTree tree,

                     Env<AttrContext> env,

                     boolean classExpected,

                     boolean interfaceExpected,

                     boolean checkExtensible) {

         Type t = tree.type != null ?

             tree.type :

             attribType(tree, env);

         return checkBase(t, tree, env, classExpected, interfaceExpected, checkExtensible);

     }

     Type checkBase(Type t,

                    JCTree tree,

                    Env<AttrContext> env,

                    boolean classExpected,

                    boolean interfaceExpected,

                    boolean checkExtensible) {

         if (t.isErroneous())

             return t;

         if (t.tag == TYPEVAR && !classExpected && !interfaceExpected) {

             // check that type variable is already visible

             if (t.getUpperBound() == null) {

                 log.error(tree.pos(), "illegal.forward.ref");

                 return types.createErrorType(t);

             }

         } else {

             t = chk.checkClassType(tree.pos(), t, checkExtensible|!allowGenerics);

         }

         if (interfaceExpected && (t.tsym.flags() & INTERFACE) == 0) {

             log.error(tree.pos(), "intf.expected.here");

             // return errType is necessary since otherwise there might

             // be undetected cycles which cause attribution to loop

             return types.createErrorType(t);

         } else if (checkExtensible &&

                    classExpected &&

                    (t.tsym.flags() & INTERFACE) != 0) {

                 log.error(tree.pos(), "no.intf.expected.here");

             return types.createErrorType(t);

         }

         if (checkExtensible &&

             ((t.tsym.flags() & FINAL) != 0)) {

             log.error(tree.pos(),

                       "cant.inherit.from.final", t.tsym);

         }

         chk.checkNonCyclic(tree.pos(), t);

         return t;

     }

     Type attribIdentAsEnumType(Env<AttrContext> env, JCIdent id) {

         Assert.check((env.enclClass.sym.flags() & ENUM) != 0);

         id.type = env.info.scope.owner.type;

         id.sym = env.info.scope.owner;

         return id.type;

     }

     public void visitClassDef(JCClassDecl tree) {

         // Local classes have not been entered yet, so we need to do it now:

         if ((env.info.scope.owner.kind & (VAR | MTH)) != 0)

             enter.classEnter(tree, env);

         ClassSymbol c = tree.sym;

         if (c == null) {

             // exit in case something drastic went wrong during enter.

             result = null;

         } else {

             // make sure class has been completed:

             c.complete();

             // If this class appears as an anonymous class

             // in a superclass constructor call where

             // no explicit outer instance is given,

             // disable implicit outer instance from being passed.

             // (This would be an illegal access to "this before super").

             if (env.info.isSelfCall &&

                 env.tree.hasTag(NEWCLASS) &&

                 ((JCNewClass) env.tree).encl == null)

             {

                 c.flags_field |= NOOUTERTHIS;

             }

             attribClass(tree.pos(), c);

             result = tree.type = c.type;

         }

     }

     public void visitMethodDef(JCMethodDecl tree) {

         MethodSymbol m = tree.sym;

         Lint lint = env.info.lint.augment(m.attributes_field, m.flags());

         Lint prevLint = chk.setLint(lint);

         MethodSymbol prevMethod = chk.setMethod(m);

         try {

             deferredLintHandler.flush(tree.pos());

             chk.checkDeprecatedAnnotation(tree.pos(), m);

             attribBounds(tree.typarams);

             // If we override any other methods, check that we do so properly.

             // JLS ???

             if (m.isStatic()) {

                 chk.checkHideClashes(tree.pos(), env.enclClass.type, m);

             } else {

                 chk.checkOverrideClashes(tree.pos(), env.enclClass.type, m);

             }

             chk.checkOverride(tree, m);

             // Create a new environment with local scope

             // for attributing the method.

             Env<AttrContext> localEnv = memberEnter.methodEnv(tree, env);

             localEnv.info.lint = lint;

             // Enter all type parameters into the local method scope.

             for (List<JCTypeParameter> l = tree.typarams; l.nonEmpty(); l = l.tail)

                 localEnv.info.scope.enterIfAbsent(l.head.type.tsym);

             ClassSymbol owner = env.enclClass.sym;

             if ((owner.flags() & ANNOTATION) != 0 &&

                 tree.params.nonEmpty())

                 log.error(tree.params.head.pos(),

                           "intf.annotation.members.cant.have.params");

             // Attribute all value parameters.

             for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {

                 attribStat(l.head, localEnv);

             }

             chk.checkVarargsMethodDecl(localEnv, tree);

             // Check that type parameters are well-formed.

             chk.validate(tree.typarams, localEnv);

             // Check that result type is well-formed.

             chk.validate(tree.restype, localEnv);

             // annotation method checks

             if ((owner.flags() & ANNOTATION) != 0) {

                 // annotation method cannot have throws clause

                 if (tree.thrown.nonEmpty()) {

                     log.error(tree.thrown.head.pos(),

                             "throws.not.allowed.in.intf.annotation");

                 }

                 // annotation method cannot declare type-parameters

                 if (tree.typarams.nonEmpty()) {

                     log.error(tree.typarams.head.pos(),

                             "intf.annotation.members.cant.have.type.params");

                 }

                 // validate annotation method's return type (could be an annotation type)

                 chk.validateAnnotationType(tree.restype);

                 // ensure that annotation method does not clash with members of Object/Annotation

                 chk.validateAnnotationMethod(tree.pos(), m);

                 if (tree.defaultValue != null) {

                     // if default value is an annotation, check it is a well-formed

                     // annotation value (e.g. no duplicate values, no missing values, etc.)

                     chk.validateAnnotationTree(tree.defaultValue);

                 }

             }

             for (List<JCExpression> l = tree.thrown; l.nonEmpty(); l = l.tail)

                 chk.checkType(l.head.pos(), l.head.type, syms.throwableType);

             if (tree.body == null) {

                 // Empty bodies are only allowed for

                 // abstract, native, or interface methods, or for methods

                 // in a retrofit signature class.

                 if ((owner.flags() & INTERFACE) == 0 &&

                     (tree.mods.flags & (ABSTRACT | NATIVE)) == 0 &&

                     !relax)

                     log.error(tree.pos(), "missing.meth.body.or.decl.abstract");

                 if (tree.defaultValue != null) {

                     if ((owner.flags() & ANNOTATION) == 0)

                         log.error(tree.pos(),

                                   "default.allowed.in.intf.annotation.member");

                 }

             } else if ((owner.flags() & INTERFACE) != 0) {

                 log.error(tree.body.pos(), "intf.meth.cant.have.body");

             } else if ((tree.mods.flags & ABSTRACT) != 0) {

                 log.error(tree.pos(), "abstract.meth.cant.have.body");

             } else if ((tree.mods.flags & NATIVE) != 0) {

                 log.error(tree.pos(), "native.meth.cant.have.body");

             } else {

                 // Add an implicit super() call unless an explicit call to

                 // super(...) or this(...) is given

                 // or we are compiling class java.lang.Object.

                 if (tree.name == names.init && owner.type != syms.objectType) {

                     JCBlock body = tree.body;

                     if (body.stats.isEmpty() ||

                         !TreeInfo.isSelfCall(body.stats.head)) {

                         body.stats = body.stats.

                             prepend(memberEnter.SuperCall(make.at(body.pos),

                                                           List.<Type>nil(),

                                                           List.<JCVariableDecl>nil(),

                                                           false));

                     } else if ((env.enclClass.sym.flags() & ENUM) != 0 &&

                                (tree.mods.flags & GENERATEDCONSTR) == 0 &&

                                TreeInfo.isSuperCall(body.stats.head)) {

                         // enum constructors are not allowed to call super

                         // directly, so make sure there aren't any super calls

                         // in enum constructors, except in the compiler

                         // generated one.

                         log.error(tree.body.stats.head.pos(),

                                   "call.to.super.not.allowed.in.enum.ctor",

                                   env.enclClass.sym);

                     }

                 }

                 // Attribute method body.

                 attribStat(tree.body, localEnv);

             }

             localEnv.info.scope.leave();

             result = tree.type = m.type;

             chk.validateAnnotations(tree.mods.annotations, m);

         }

         finally {

             chk.setLint(prevLint);

             chk.setMethod(prevMethod);

         }

     }

     public void visitVarDef(JCVariableDecl tree) {

         // Local variables have not been entered yet, so we need to do it now:

         if (env.info.scope.owner.kind == MTH) {

             if (tree.sym != null) {

                 // parameters have already been entered

                 env.info.scope.enter(tree.sym);

             } else {

                 memberEnter.memberEnter(tree, env);

                 annotate.flush();

             }

         }

         VarSymbol v = tree.sym;

         Lint lint = env.info.lint.augment(v.attributes_field, v.flags());

         Lint prevLint = chk.setLint(lint);

         // Check that the variable's declared type is well-formed.

         chk.validate(tree.vartype, env);

         deferredLintHandler.flush(tree.pos());

         try {

             chk.checkDeprecatedAnnotation(tree.pos(), v);

             if (tree.init != null) {

                 if ((v.flags_field & FINAL) != 0 && !tree.init.hasTag(NEWCLASS)) {

                     // In this case, `v' is final.  Ensure that it's initializer is

                     // evaluated.

                     v.getConstValue(); // ensure initializer is evaluated

                 } else {

                     // Attribute initializer in a new environment

                     // with the declared variable as owner.

                     // Check that initializer conforms to variable's declared type.

                     Env<AttrContext> initEnv = memberEnter.initEnv(tree, env);

                     initEnv.info.lint = lint;

                     // In order to catch self-references, we set the variable's

                     // declaration position to maximal possible value, effectively

                     // marking the variable as undefined.

                     initEnv.info.enclVar = v;

                     attribExpr(tree.init, initEnv, v.type);

                 }

             }

             result = tree.type = v.type;

             chk.validateAnnotations(tree.mods.annotations, v);

         }

         finally {

             chk.setLint(prevLint);

         }

     }

     public void visitSkip(JCSkip tree) {

         result = null;

     }

     public void visitBlock(JCBlock tree) {

         if (env.info.scope.owner.kind == TYP) {

             // Block is a static or instance initializer;

             // let the owner of the environment be a freshly

             // created BLOCK-method.

             Env<AttrContext> localEnv =

                 env.dup(tree, env.info.dup(env.info.scope.dupUnshared()));

             localEnv.info.scope.owner =

                 new MethodSymbol(tree.flags | BLOCK, names.empty, null,

                                  env.info.scope.owner);

             if ((tree.flags & STATIC) != 0) localEnv.info.staticLevel++;

             attribStats(tree.stats, localEnv);

         } else {

             // Create a new local environment with a local scope.

             Env<AttrContext> localEnv =

                 env.dup(tree, env.info.dup(env.info.scope.dup()));

             attribStats(tree.stats, localEnv);

             localEnv.info.scope.leave();

         }

         result = null;

     }

     public void visitDoLoop(JCDoWhileLoop tree) {

         attribStat(tree.body, env.dup(tree));

         attribExpr(tree.cond, env, syms.booleanType);

         result = null;

     }

     public void visitWhileLoop(JCWhileLoop tree) {

         attribExpr(tree.cond, env, syms.booleanType);

         attribStat(tree.body, env.dup(tree));

         result = null;

     }

     public void visitForLoop(JCForLoop tree) {

         Env<AttrContext> loopEnv =

             env.dup(env.tree, env.info.dup(env.info.scope.dup()));

         attribStats(tree.init, loopEnv);

         if (tree.cond != null) attribExpr(tree.cond, loopEnv, syms.booleanType);

         loopEnv.tree = tree; // before, we were not in loop!

         attribStats(tree.step, loopEnv);

         attribStat(tree.body, loopEnv);

         loopEnv.info.scope.leave();

         result = null;

     }

     public void visitForeachLoop(JCEnhancedForLoop tree) {

         Env<AttrContext> loopEnv =

             env.dup(env.tree, env.info.dup(env.info.scope.dup()));

         attribStat(tree.var, loopEnv);

         Type exprType = types.upperBound(attribExpr(tree.expr, loopEnv));

         chk.checkNonVoid(tree.pos(), exprType);

         Type elemtype = types.elemtype(exprType); // perhaps expr is an array?

         if (elemtype == null) {

             // or perhaps expr implements Iterable<T>?

             Type base = types.asSuper(exprType, syms.iterableType.tsym);

             if (base == null) {

                 log.error(tree.expr.pos(),

                         "foreach.not.applicable.to.type",

                         exprType,

                         diags.fragment("type.req.array.or.iterable"));

                 elemtype = types.createErrorType(exprType);

             } else {

                 List<Type> iterableParams = base.allparams();

                 elemtype = iterableParams.isEmpty()

                     ? syms.objectType

                     : types.upperBound(iterableParams.head);

             }

         }

         chk.checkType(tree.expr.pos(), elemtype, tree.var.sym.type);

         loopEnv.tree = tree; // before, we were not in loop!

         attribStat(tree.body, loopEnv);

         loopEnv.info.scope.leave();

         result = null;

     }

     public void visitLabelled(JCLabeledStatement tree) {

         // Check that label is not used in an enclosing statement

         Env<AttrContext> env1 = env;

         while (env1 != null && !env1.tree.hasTag(CLASSDEF)) {

             if (env1.tree.hasTag(LABELLED) &&

                 ((JCLabeledStatement) env1.tree).label == tree.label) {

                 log.error(tree.pos(), "label.already.in.use",

                           tree.label);

                 break;

             }

             env1 = env1.next;

         }

         attribStat(tree.body, env.dup(tree));

         result = null;

     }

     public void visitSwitch(JCSwitch tree) {

         Type seltype = attribExpr(tree.selector, env);

         Env<AttrContext> switchEnv =

             env.dup(tree, env.info.dup(env.info.scope.dup()));

         boolean enumSwitch =

             allowEnums &&

             (seltype.tsym.flags() & Flags.ENUM) != 0;

         boolean stringSwitch = false;

         if (types.isSameType(seltype, syms.stringType)) {

             if (allowStringsInSwitch) {

                 stringSwitch = true;

             } else {

                 log.error(tree.selector.pos(), "string.switch.not.supported.in.source", sourceName);

             }

         }

         if (!enumSwitch && !stringSwitch)

             seltype = chk.checkType(tree.selector.pos(), seltype, syms.intType);

         // Attribute all cases and

         // check that there are no duplicate case labels or default clauses.

         Set<Object> labels = new HashSet<Object>(); // The set of case labels.

         boolean hasDefault = false;      // Is there a default label?

         for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {

             JCCase c = l.head;

             Env<AttrContext> caseEnv =

                 switchEnv.dup(c, env.info.dup(switchEnv.info.scope.dup()));

             if (c.pat != null) {

                 if (enumSwitch) {

                     Symbol sym = enumConstant(c.pat, seltype);

                     if (sym == null) {

                         log.error(c.pat.pos(), "enum.label.must.be.unqualified.enum");

                     } else if (!labels.add(sym)) {

                         log.error(c.pos(), "duplicate.case.label");

                     }

                 } else {

                     Type pattype = attribExpr(c.pat, switchEnv, seltype);

                     if (pattype.tag != ERROR) {

                         if (pattype.constValue() == null) {

                             log.error(c.pat.pos(),

                                       (stringSwitch ? "string.const.req" : "const.expr.req"));

                         } else if (labels.contains(pattype.constValue())) {

                             log.error(c.pos(), "duplicate.case.label");

                         } else {

                             labels.add(pattype.constValue());

                         }

                     }

                 }

             } else if (hasDefault) {

                 log.error(c.pos(), "duplicate.default.label");

             } else {

                 hasDefault = true;

             }

             attribStats(c.stats, caseEnv);

             caseEnv.info.scope.leave();

             addVars(c.stats, switchEnv.info.scope);

         }

         switchEnv.info.scope.leave();

         result = null;

     }

     // where

         /** Add any variables defined in stats to the switch scope. */

         private static void addVars(List<JCStatement> stats, Scope switchScope) {

             for (;stats.nonEmpty(); stats = stats.tail) {

                 JCTree stat = stats.head;

                 if (stat.hasTag(VARDEF))

                     switchScope.enter(((JCVariableDecl) stat).sym);

             }

         }

     // where

     /** Return the selected enumeration constant symbol, or null. */

     private Symbol enumConstant(JCTree tree, Type enumType) {

         if (!tree.hasTag(IDENT)) {

             log.error(tree.pos(), "enum.label.must.be.unqualified.enum");

             return syms.errSymbol;

         }

         JCIdent ident = (JCIdent)tree;

         Name name = ident.name;

         for (Scope.Entry e = enumType.tsym.members().lookup(name);

              e.scope != null; e = e.next()) {

             if (e.sym.kind == VAR) {

                 Symbol s = ident.sym = e.sym;

                 ((VarSymbol)s).getConstValue(); // ensure initializer is evaluated

                 ident.type = s.type;

                 return ((s.flags_field & Flags.ENUM) == 0)

                     ? null : s;

             }

         }

         return null;

     }

     public void visitSynchronized(JCSynchronized tree) {

         chk.checkRefType(tree.pos(), attribExpr(tree.lock, env));

         attribStat(tree.body, env);

         result = null;

     }

     public void visitTry(JCTry tree) {

         // Create a new local environment with a local

         Env<AttrContext> localEnv = env.dup(tree, env.info.dup(env.info.scope.dup()));

         boolean isTryWithResource = tree.resources.nonEmpty();

         // Create a nested environment for attributing the try block if needed

         Env<AttrContext> tryEnv = isTryWithResource ?

             env.dup(tree, localEnv.info.dup(localEnv.info.scope.dup())) :

             localEnv;

         // Attribute resource declarations

         for (JCTree resource : tree.resources) {

             CheckContext twrContext = new Check.NestedCheckContext(resultInfo.checkContext) {

                 @Override

                 public void report(DiagnosticPosition pos, JCDiagnostic details) {

                     chk.basicHandler.report(pos, diags.fragment("try.not.applicable.to.type", details));

                 }

             };

             ResultInfo twrResult = new ResultInfo(VAL, syms.autoCloseableType, twrContext);

             if (resource.hasTag(VARDEF)) {

                 attribStat(resource, tryEnv);

                 twrResult.check(resource, resource.type);

                 //check that resource type cannot throw InterruptedException

                 checkAutoCloseable(resource.pos(), localEnv, resource.type);

                 VarSymbol var = (VarSymbol)TreeInfo.symbolFor(resource);

                 var.setData(ElementKind.RESOURCE_VARIABLE);

             } else {

                 attribTree(resource, tryEnv, twrResult);

             }

         }

         // Attribute body

         attribStat(tree.body, tryEnv);

         if (isTryWithResource)

             tryEnv.info.scope.leave();

         // Attribute catch clauses

         for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {

             JCCatch c = l.head;

             Env<AttrContext> catchEnv =

                 localEnv.dup(c, localEnv.info.dup(localEnv.info.scope.dup()));

             Type ctype = attribStat(c.param, catchEnv);

             if (TreeInfo.isMultiCatch(c)) {

                 //multi-catch parameter is implicitly marked as final

                 c.param.sym.flags_field |= FINAL | UNION;

             }

             if (c.param.sym.kind == Kinds.VAR) {

                 c.param.sym.setData(ElementKind.EXCEPTION_PARAMETER);

             }

             chk.checkType(c.param.vartype.pos(),

                           chk.checkClassType(c.param.vartype.pos(), ctype),

                           syms.throwableType);

             attribStat(c.body, catchEnv);

             catchEnv.info.scope.leave();

         }

         // Attribute finalizer

         if (tree.finalizer != null) attribStat(tree.finalizer, localEnv);

         localEnv.info.scope.leave();

         result = null;

     }

     void checkAutoCloseable(DiagnosticPosition pos, Env<AttrContext> env, Type resource) {

         if (!resource.isErroneous() &&

             types.asSuper(resource, syms.autoCloseableType.tsym) != null &&

             !types.isSameType(resource, syms.autoCloseableType)) { // Don't emit warning for AutoCloseable itself

             Symbol close = syms.noSymbol;

             boolean prevDeferDiags = log.deferDiagnostics;

             Queue<JCDiagnostic> prevDeferredDiags = log.deferredDiagnostics;

             try {

                 log.deferDiagnostics = true;

                 log.deferredDiagnostics = ListBuffer.lb();

                 close = rs.resolveQualifiedMethod(pos,

                         env,

                         resource,

                         names.close,

                         List.<Type>nil(),

                         List.<Type>nil());

             }

             finally {

                 log.deferDiagnostics = prevDeferDiags;

                 log.deferredDiagnostics = prevDeferredDiags;

             }

             if (close.kind == MTH &&

                     close.overrides(syms.autoCloseableClose, resource.tsym, types, true) &&

                     chk.isHandled(syms.interruptedExceptionType, types.memberType(resource, close).getThrownTypes()) &&

                     env.info.lint.isEnabled(LintCategory.TRY)) {

                 log.warning(LintCategory.TRY, pos, "try.resource.throws.interrupted.exc", resource);

             }

         }

     }

     public void visitConditional(JCConditional tree) {

         attribExpr(tree.cond, env, syms.booleanType);

         attribExpr(tree.truepart, env);

         attribExpr(tree.falsepart, env);

         result = check(tree,

                        capture(condType(tree.pos(), tree.cond.type,

                                         tree.truepart.type, tree.falsepart.type)),

                        VAL, resultInfo);

     }

     //where

         /** Compute the type of a conditional expression, after

          *  checking that it exists. See Spec 15.25.

          *

          *  @param pos      The source position to be used for

          *                  error diagnostics.

          *  @param condtype The type of the expression's condition.

          *  @param thentype The type of the expression's then-part.

          *  @param elsetype The type of the expression's else-part.

          */

         private Type condType(DiagnosticPosition pos,

                               Type condtype,

                               Type thentype,

                               Type elsetype) {

             Type ctype = condType1(pos, condtype, thentype, elsetype);

             // If condition and both arms are numeric constants,

             // evaluate at compile-time.

             return ((condtype.constValue() != null) &&

                     (thentype.constValue() != null) &&

                     (elsetype.constValue() != null))

                 ? cfolder.coerce(condtype.isTrue()?thentype:elsetype, ctype)

                 : ctype;

         }

         /** Compute the type of a conditional expression, after

          *  checking that it exists.  Does not take into

          *  account the special case where condition and both arms

          *  are constants.

          *

          *  @param pos      The source position to be used for error

          *                  diagnostics.

          *  @param condtype The type of the expression's condition.

          *  @param thentype The type of the expression's then-part.

          *  @param elsetype The type of the expression's else-part.

          */

         private Type condType1(DiagnosticPosition pos, Type condtype,

                                Type thentype, Type elsetype) {

             // If same type, that is the result

             if (types.isSameType(thentype, elsetype))

                 return thentype.baseType();

             Type thenUnboxed = (!allowBoxing || thentype.isPrimitive())

                 ? thentype : types.unboxedType(thentype);

             Type elseUnboxed = (!allowBoxing || elsetype.isPrimitive())

                 ? elsetype : types.unboxedType(elsetype);

             // Otherwise, if both arms can be converted to a numeric

             // type, return the least numeric type that fits both arms

             // (i.e. return larger of the two, or return int if one

             // arm is short, the other is char).

             if (thenUnboxed.isPrimitive() && elseUnboxed.isPrimitive()) {

                 // If one arm has an integer subrange type (i.e., byte,

                 // short, or char), and the other is an integer constant

                 // that fits into the subrange, return the subrange type.

                 if (thenUnboxed.tag < INT && elseUnboxed.tag == INT &&

                     types.isAssignable(elseUnboxed, thenUnboxed))

                     return thenUnboxed.baseType();

                 if (elseUnboxed.tag < INT && thenUnboxed.tag == INT &&

                     types.isAssignable(thenUnboxed, elseUnboxed))

                     return elseUnboxed.baseType();

                 for (int i = BYTE; i < VOID; i++) {

                     Type candidate = syms.typeOfTag[i];

                     if (types.isSubtype(thenUnboxed, candidate) &&

                         types.isSubtype(elseUnboxed, candidate))

                         return candidate;

                 }

             }

             // Those were all the cases that could result in a primitive

             if (allowBoxing) {

                 if (thentype.isPrimitive())

                     thentype = types.boxedClass(thentype).type;

                 if (elsetype.isPrimitive())

                     elsetype = types.boxedClass(elsetype).type;

             }

             if (types.isSubtype(thentype, elsetype))

                 return elsetype.baseType();

             if (types.isSubtype(elsetype, thentype))

                 return thentype.baseType();

             if (!allowBoxing || thentype.tag == VOID || elsetype.tag == VOID) {

                 log.error(pos, "neither.conditional.subtype",

                           thentype, elsetype);

                 return thentype.baseType();

             }

             // both are known to be reference types.  The result is

             // lub(thentype,elsetype). This cannot fail, as it will

             // always be possible to infer "Object" if nothing better.

             return types.lub(thentype.baseType(), elsetype.baseType());

         }

     public void visitIf(JCIf tree) {

         attribExpr(tree.cond, env, syms.booleanType);

         attribStat(tree.thenpart, env);

         if (tree.elsepart != null)

             attribStat(tree.elsepart, env);

         chk.checkEmptyIf(tree);

         result = null;

     }

     public void visitExec(JCExpressionStatement tree) {

         //a fresh environment is required for 292 inference to work properly ---

         //see Infer.instantiatePolymorphicSignatureInstance()

         Env<AttrContext> localEnv = env.dup(tree);

         attribExpr(tree.expr, localEnv);

         result = null;

     }

     public void visitBreak(JCBreak tree) {

         tree.target = findJumpTarget(tree.pos(), tree.getTag(), tree.label, env);

         result = null;

     }

     public void visitContinue(JCContinue tree) {

         tree.target = findJumpTarget(tree.pos(), tree.getTag(), tree.label, env);

         result = null;

     }

     //where

         /** Return the target of a break or continue statement, if it exists,

          *  report an error if not.

          *  Note: The target of a labelled break or continue is the

          *  (non-labelled) statement tree referred to by the label,

          *  not the tree representing the labelled statement itself.

          *

          *  @param pos     The position to be used for error diagnostics

          *  @param tag     The tag of the jump statement. This is either

          *                 Tree.BREAK or Tree.CONTINUE.

          *  @param label   The label of the jump statement, or null if no

          *                 label is given.

          *  @param env     The environment current at the jump statement.

          */

         private JCTree findJumpTarget(DiagnosticPosition pos,

                                     JCTree.Tag tag,

                                     Name label,

                                     Env<AttrContext> env) {

             // Search environments outwards from the point of jump.

             Env<AttrContext> env1 = env;

             LOOP:

             while (env1 != null) {

                 switch (env1.tree.getTag()) {

                 case LABELLED:

                     JCLabeledStatement labelled = (JCLabeledStatement)env1.tree;

                     if (label == labelled.label) {

                         // If jump is a continue, check that target is a loop.

                         if (tag == CONTINUE) {

                             if (!labelled.body.hasTag(DOLOOP) &&

                                 !labelled.body.hasTag(WHILELOOP) &&

                                 !labelled.body.hasTag(FORLOOP) &&

                                 !labelled.body.hasTag(FOREACHLOOP))

                                 log.error(pos, "not.loop.label", label);

                             // Found labelled statement target, now go inwards

                             // to next non-labelled tree.

                             return TreeInfo.referencedStatement(labelled);

                         } else {

                             return labelled;

                         }

                     }

                     break;

                 case DOLOOP:

                 case WHILELOOP:

                 case FORLOOP:

                 case FOREACHLOOP:

                     if (label == null) return env1.tree;

                     break;

                 case SWITCH:

                     if (label == null && tag == BREAK) return env1.tree;

                     break;

                 case METHODDEF:

                 case CLASSDEF:

                     break LOOP;

                 default:

                 }

                 env1 = env1.next;

             }

             if (label != null)

                 log.error(pos, "undef.label", label);

             else if (tag == CONTINUE)

                 log.error(pos, "cont.outside.loop");

             else

                 log.error(pos, "break.outside.switch.loop");

             return null;

         }

     public void visitReturn(JCReturn tree) {

         // Check that there is an enclosing method which is

         // nested within than the enclosing class.

         if (env.enclMethod == null ||

             env.enclMethod.sym.owner != env.enclClass.sym) {

             log.error(tree.pos(), "ret.outside.meth");

         } else {

             // Attribute return expression, if it exists, and check that

             // it conforms to result type of enclosing method.

             Symbol m = env.enclMethod.sym;

             if (m.type.getReturnType().tag == VOID) {

                 if (tree.expr != null)

                     log.error(tree.expr.pos(),

                               "cant.ret.val.from.meth.decl.void");

             } else if (tree.expr == null) {

                 log.error(tree.pos(), "missing.ret.val");

             } else {

                 attribExpr(tree.expr, env, m.type.getReturnType());

             }

         }

         result = null;

     }

     public void visitThrow(JCThrow tree) {

         attribExpr(tree.expr, env, syms.throwableType);

         result = null;

     }

     public void visitAssert(JCAssert tree) {

         attribExpr(tree.cond, env, syms.booleanType);

         if (tree.detail != null) {

             chk.checkNonVoid(tree.detail.pos(), attribExpr(tree.detail, env));

         }

         result = null;

     }

      /** Visitor method for method invocations.

      *  NOTE: The method part of an application will have in its type field

      *        the return type of the method, not the method's type itself!

      */

     public void visitApply(JCMethodInvocation tree) {

         // The local environment of a method application is

         // a new environment nested in the current one.

         Env<AttrContext> localEnv = env.dup(tree, env.info.dup());

         // The types of the actual method arguments.

         List<Type> argtypes;

         // The types of the actual method type arguments.

         List<Type> typeargtypes = null;

         Name methName = TreeInfo.name(tree.meth);

         boolean isConstructorCall =

             methName == names._this || methName == names._super;

         if (isConstructorCall) {

             // We are seeing a ...this(...) or ...super(...) call.

             // Check that this is the first statement in a constructor.

             if (checkFirstConstructorStat(tree, env)) {

                 // Record the fact

                 // that this is a constructor call (using isSelfCall).

                 localEnv.info.isSelfCall = true;

                 // Attribute arguments, yielding list of argument types.

                 argtypes = attribArgs(tree.args, localEnv);

                 typeargtypes = attribTypes(tree.typeargs, localEnv);

                 // Variable `site' points to the class in which the called

                 // constructor is defined.

                 Type site = env.enclClass.sym.type;

                 if (methName == names._super) {

                     if (site == syms.objectType) {

                         log.error(tree.meth.pos(), "no.superclass", site);

                         site = types.createErrorType(syms.objectType);

                     } else {

                         site = types.supertype(site);

                     }

                 }

                 if (site.tag == CLASS) {

                     Type encl = site.getEnclosingType();

                     while (encl != null && encl.tag == TYPEVAR)

                         encl = encl.getUpperBound();

                     if (encl.tag == CLASS) {

                         // we are calling a nested class

                         if (tree.meth.hasTag(SELECT)) {

                             JCTree qualifier = ((JCFieldAccess) tree.meth).selected;

                             // We are seeing a prefixed call, of the form

                             //     <expr>.super(...).

                             // Check that the prefix expression conforms

                             // to the outer instance type of the class.

                             chk.checkRefType(qualifier.pos(),

                                              attribExpr(qualifier, localEnv,

                                                         encl));

                         } else if (methName == names._super) {

                             // qualifier omitted; check for existence

                             // of an appropriate implicit qualifier.

                             rs.resolveImplicitThis(tree.meth.pos(),

                                                    localEnv, site, true);

                         }

                     } else if (tree.meth.hasTag(SELECT)) {

                         log.error(tree.meth.pos(), "illegal.qual.not.icls",

                                   site.tsym);

                     }

                     // if we're calling a java.lang.Enum constructor,

                     // prefix the implicit String and int parameters

                     if (site.tsym == syms.enumSym && allowEnums)

                         argtypes = argtypes.prepend(syms.intType).prepend(syms.stringType);

                     // Resolve the called constructor under the assumption

                     // that we are referring to a superclass instance of the

                     // current instance (JLS ???).

                     boolean selectSuperPrev = localEnv.info.selectSuper;

                     localEnv.info.selectSuper = true;

                     localEnv.info.varArgs = false;

                     Symbol sym = rs.resolveConstructor(

                         tree.meth.pos(), localEnv, site, argtypes, typeargtypes);

                     localEnv.info.selectSuper = selectSuperPrev;

                     // Set method symbol to resolved constructor...

                     TreeInfo.setSymbol(tree.meth, sym);

                     // ...and check that it is legal in the current context.

                     // (this will also set the tree's type)

                     Type mpt = newMethodTemplate(resultInfo.pt, argtypes, typeargtypes);

                     checkId(tree.meth, site, sym, localEnv, new ResultInfo(MTH, mpt),

                             tree.varargsElement != null);

                 }

                 // Otherwise, `site' is an error type and we do nothing

             }

             result = tree.type = syms.voidType;

         } else {

             // Otherwise, we are seeing a regular method call.

             // Attribute the arguments, yielding list of argument types, ...

             argtypes = attribArgs(tree.args, localEnv);

             typeargtypes = attribAnyTypes(tree.typeargs, localEnv);

             // ... and attribute the method using as a prototype a methodtype

             // whose formal argument types is exactly the list of actual

             // arguments (this will also set the method symbol).

             Type mpt = newMethodTemplate(resultInfo.pt, argtypes, typeargtypes);

             localEnv.info.varArgs = false;

             Type mtype = attribExpr(tree.meth, localEnv, mpt);

             // Compute the result type.

             Type restype = mtype.getReturnType();

             if (restype.tag == WILDCARD)

                 throw new AssertionError(mtype);

             // as a special case, array.clone() has a result that is

             // the same as static type of the array being cloned

             if (tree.meth.hasTag(SELECT) &&

                 allowCovariantReturns &&

                 methName == names.clone &&

                 types.isArray(((JCFieldAccess) tree.meth).selected.type))

                 restype = ((JCFieldAccess) tree.meth).selected.type;

             // as a special case, x.getClass() has type Class<? extends |X|>

             if (allowGenerics &&

                 methName == names.getClass && tree.args.isEmpty()) {

                 Type qualifier = (tree.meth.hasTag(SELECT))

                     ? ((JCFieldAccess) tree.meth).selected.type

                     : env.enclClass.sym.type;

                 restype = new

                     ClassType(restype.getEnclosingType(),

                               List.<Type>of(new WildcardType(types.erasure(qualifier),

                                                                BoundKind.EXTENDS,

                                                                syms.boundClass)),

                               restype.tsym);

             }

             chk.checkRefTypes(tree.typeargs, typeargtypes);

             // Check that value of resulting type is admissible in the

             // current context.  Also, capture the return type

             result = check(tree, capture(restype), VAL, resultInfo);

             if (localEnv.info.varArgs)

                 Assert.check(result.isErroneous() || tree.varargsElement != null);

         }

         chk.validate(tree.typeargs, localEnv);

     }

     //where

         /** Check that given application node appears as first statement

          *  in a constructor call.

          *  @param tree   The application node

          *  @param env    The environment current at the application.

          */

         boolean checkFirstConstructorStat(JCMethodInvocation tree, Env<AttrContext> env) {

             JCMethodDecl enclMethod = env.enclMethod;

             if (enclMethod != null && enclMethod.name == names.init) {

                 JCBlock body = enclMethod.body;

                 if (body.stats.head.hasTag(EXEC) &&

                     ((JCExpressionStatement) body.stats.head).expr == tree)

                     return true;

             }

             log.error(tree.pos(),"call.must.be.first.stmt.in.ctor",

                       TreeInfo.name(tree.meth));

             return false;

         }

         /** Obtain a method type with given argument types.

          */

         Type newMethodTemplate(Type restype, List<Type> argtypes, List<Type> typeargtypes) {

             MethodType mt = new MethodType(argtypes, restype, null, syms.methodClass);

             return (typeargtypes == null) ? mt : (Type)new ForAll(typeargtypes, mt);

         }

     public void visitNewClass(JCNewClass tree) {

         Type owntype = types.createErrorType(tree.type);

         // The local environment of a class creation is

         // a new environment nested in the current one.

         Env<AttrContext> localEnv = env.dup(tree, env.info.dup());

         // The anonymous inner class definition of the new expression,

         // if one is defined by it.

         JCClassDecl cdef = tree.def;

         // If enclosing class is given, attribute it, and

         // complete class name to be fully qualified

         JCExpression clazz = tree.clazz; // Class field following new

         JCExpression clazzid =          // Identifier in class field

             (clazz.hasTag(TYPEAPPLY))

             ? ((JCTypeApply) clazz).clazz

             : clazz;

         JCExpression clazzid1 = clazzid; // The same in fully qualified form

         if (tree.encl != null) {

             // We are seeing a qualified new, of the form

             //    <expr>.new C <...> (...) ...

             // In this case, we let clazz stand for the name of the

             // allocated class C prefixed with the type of the qualifier

             // expression, so that we can

             // resolve it with standard techniques later. I.e., if

             // <expr> has type T, then <expr>.new C <...> (...)

             // yields a clazz T.C.

             Type encltype = chk.checkRefType(tree.encl.pos(),

                                              attribExpr(tree.encl, env));

             clazzid1 = make.at(clazz.pos).Select(make.Type(encltype),

                                                  ((JCIdent) clazzid).name);

             if (clazz.hasTag(TYPEAPPLY))

                 clazz = make.at(tree.pos).

                     TypeApply(clazzid1,

                               ((JCTypeApply) clazz).arguments);

             else

                 clazz = clazzid1;

         }

         // Attribute clazz expression and store

         // symbol + type back into the attributed tree.

         Type clazztype = TreeInfo.isEnumInit(env.tree) ?

             attribIdentAsEnumType(env, (JCIdent)clazz) :

             attribType(clazz, env);

         clazztype = chk.checkDiamond(tree, clazztype);

         chk.validate(clazz, localEnv);

         if (tree.encl != null) {

             // We have to work in this case to store

             // symbol + type back into the attributed tree.

             tree.clazz.type = clazztype;

             TreeInfo.setSymbol(clazzid, TreeInfo.symbol(clazzid1));

             clazzid.type = ((JCIdent) clazzid).sym.type;

             if (!clazztype.isErroneous()) {

                 if (cdef != null && clazztype.tsym.isInterface()) {

                     log.error(tree.encl.pos(), "anon.class.impl.intf.no.qual.for.new");

                 } else if (clazztype.tsym.isStatic()) {

                     log.error(tree.encl.pos(), "qualified.new.of.static.class", clazztype.tsym);

                 }

             }

         } else if (!clazztype.tsym.isInterface() &&

                    clazztype.getEnclosingType().tag == CLASS) {

             // Check for the existence of an apropos outer instance

             rs.resolveImplicitThis(tree.pos(), env, clazztype);

         }

         // Attribute constructor arguments.

         List<Type> argtypes = attribArgs(tree.args, localEnv);

         List<Type> typeargtypes = attribTypes(tree.typeargs, localEnv);

         if (TreeInfo.isDiamond(tree) && !clazztype.isErroneous()) {

             clazztype = attribDiamond(localEnv, tree, clazztype, argtypes, typeargtypes);

             clazz.type = clazztype;

         } else if (allowDiamondFinder &&

                 tree.def == null &&

                 !clazztype.isErroneous() &&

                 clazztype.getTypeArguments().nonEmpty() &&

                 findDiamonds) {

             boolean prevDeferDiags = log.deferDiagnostics;

             Queue<JCDiagnostic> prevDeferredDiags = log.deferredDiagnostics;

             Type inferred = null;

             try {

                 //disable diamond-related diagnostics

                 log.deferDiagnostics = true;

                 log.deferredDiagnostics = ListBuffer.lb();

                 inferred = attribDiamond(localEnv,

                         tree,

                         clazztype,

                         argtypes,

                         typeargtypes);

             }

             finally {

                 log.deferDiagnostics = prevDeferDiags;

                 log.deferredDiagnostics = prevDeferredDiags;

             }

             if (inferred != null &&

                     !inferred.isErroneous() &&

                     inferred.tag == CLASS &&

                     types.isAssignable(inferred, pt().tag == NONE ? clazztype : pt(), Warner.noWarnings)) {

                 String key = types.isSameType(clazztype, inferred) ?

                     "diamond.redundant.args" :

                     "diamond.redundant.args.1";

                 log.warning(tree.clazz.pos(), key, clazztype, inferred);

             }

         }

         // If we have made no mistakes in the class type...

         if (clazztype.tag == CLASS) {

             // Enums may not be instantiated except implicitly

             if (allowEnums &&

                 (clazztype.tsym.flags_field&Flags.ENUM) != 0 &&

                 (!env.tree.hasTag(VARDEF) ||

                  (((JCVariableDecl) env.tree).mods.flags&Flags.ENUM) == 0 ||

                  ((JCVariableDecl) env.tree).init != tree))

                 log.error(tree.pos(), "enum.cant.be.instantiated");

             // Check that class is not abstract

             if (cdef == null &&

                 (clazztype.tsym.flags() & (ABSTRACT | INTERFACE)) != 0) {

                 log.error(tree.pos(), "abstract.cant.be.instantiated",

                           clazztype.tsym);

             } else if (cdef != null && clazztype.tsym.isInterface()) {

                 // Check that no constructor arguments are given to

                 // anonymous classes implementing an interface

                 if (!argtypes.isEmpty())

                     log.error(tree.args.head.pos(), "anon.class.impl.intf.no.args");

                 if (!typeargtypes.isEmpty())

                     log.error(tree.typeargs.head.pos(), "anon.class.impl.intf.no.typeargs");

                 // Error recovery: pretend no arguments were supplied.

                 argtypes = List.nil();

                 typeargtypes = List.nil();

             }

             // Resolve the called constructor under the assumption

             // that we are referring to a superclass instance of the

             // current instance (JLS ???).

             else {

                 //the following code alters some of the fields in the current

                 //AttrContext - hence, the current context must be dup'ed in

                 //order to avoid downstream failures

                 Env<AttrContext> rsEnv = localEnv.dup(tree);

                 rsEnv.info.selectSuper = cdef != null;

                 rsEnv.info.varArgs = false;

                 tree.constructor = rs.resolveConstructor(

                     tree.pos(), rsEnv, clazztype, argtypes, typeargtypes);

                 tree.constructorType = tree.constructor.type.isErroneous() ?

                     syms.errType :

                     checkConstructor(clazztype,

                         tree.constructor,

                         rsEnv,

                         tree.args,

                         argtypes,

                         typeargtypes,

                         rsEnv.info.varArgs);

                 if (rsEnv.info.varArgs)

                     Assert.check(tree.constructorType.isErroneous() || tree.varargsElement != null);

             }

             if (cdef != null) {

                 // We are seeing an anonymous class instance creation.

                 // In this case, the class instance creation

                 // expression

                 //

                 //    E.new <typeargs1>C<typargs2>(args) { ... }

                 //

                 // is represented internally as

                 //

                 //    E . new <typeargs1>C<typargs2>(args) ( class <empty-name> { ... } )  .

                 //

                 // This expression is then *transformed* as follows:

                 //

                 // (1) add a STATIC flag to the class definition

                 //     if the current environment is static

                 // (2) add an extends or implements clause

                 // (3) add a constructor.

                 //

                 // For instance, if C is a class, and ET is the type of E,

                 // the expression

                 //

                 //    E.new <typeargs1>C<typargs2>(args) { ... }

                 //

                 // is translated to (where X is a fresh name and typarams is the

                 // parameter list of the super constructor):

                 //

                 //   new <typeargs1>X(<*nullchk*>E, args) where

                 //     X extends C<typargs2> {

                 //       <typarams> X(ET e, args) {

                 //         e.<typeargs1>super(args)

                 //       }

                 //       ...

                 //     }

                 if (Resolve.isStatic(env)) cdef.mods.flags |= STATIC;

                 if (clazztype.tsym.isInterface()) {

                     cdef.implementing = List.of(clazz);

                 } else {

                     cdef.extending = clazz;

                 }

                 attribStat(cdef, localEnv);

                 // If an outer instance is given,

                 // prefix it to the constructor arguments

                 // and delete it from the new expression

                 if (tree.encl != null && !clazztype.tsym.isInterface()) {

                     tree.args = tree.args.prepend(makeNullCheck(tree.encl));

                     argtypes = argtypes.prepend(tree.encl.type);

                     tree.encl = null;

                 }

                 // Reassign clazztype and recompute constructor.

                 clazztype = cdef.sym.type;

                 boolean useVarargs = tree.varargsElement != null;

                 Symbol sym = rs.resolveConstructor(

                     tree.pos(), localEnv, clazztype, argtypes,

                     typeargtypes, true, useVarargs);

                 Assert.check(sym.kind < AMBIGUOUS || tree.constructor.type.isErroneous());

                 tree.constructor = sym;

                 if (tree.constructor.kind > ERRONEOUS) {

                     tree.constructorType =  syms.errType;

                 }

                 else {

                     tree.constructorType = checkConstructor(clazztype,

                             tree.constructor,

                             localEnv,

                             tree.args,

                             argtypes,

                             typeargtypes,

                             useVarargs);

                 }

             }

             if (tree.constructor != null && tree.constructor.kind == MTH)

                 owntype = clazztype;

         }

         result = check(tree, owntype, VAL, resultInfo);

         chk.validate(tree.typeargs, localEnv);

     }

     Type attribDiamond(Env<AttrContext> env,

                         final JCNewClass tree,

                         final Type clazztype,

                         List<Type> argtypes,

                         List<Type> typeargtypes) {

         if (clazztype.isErroneous() ||

                 clazztype.isInterface()) {

             //if the type of the instance creation expression is erroneous,

             //or if it's an interface, or if something prevented us to form a valid

             //mapping, return the (possibly erroneous) type unchanged

             return clazztype;

         }

         //dup attribution environment and augment the set of inference variables

         Env<AttrContext> localEnv = env.dup(tree);

         ClassType site = new ClassType(clazztype.getEnclosingType(),

                     clazztype.tsym.type.getTypeArguments(),

                     clazztype.tsym);

         //if the type of the instance creation expression is a class type

         //apply method resolution inference (JLS 15.12.2.7). The return type

         //of the resolved constructor will be a partially instantiated type

         Symbol constructor = rs.resolveDiamond(tree.pos(),

                     localEnv,

                     site,

                     argtypes,

                     typeargtypes);

         Type owntype = types.createErrorType(clazztype);

         if (constructor.kind == MTH) {

             ResultInfo diamondResult = new ResultInfo(VAL, resultInfo.pt, new Check.NestedCheckContext(resultInfo.checkContext) {

                 @Override

                 public void report(DiagnosticPosition pos, JCDiagnostic details) {

                     enclosingContext.report(tree.clazz.pos(),

                             diags.fragment("cant.apply.diamond.1", diags.fragment("diamond", clazztype.tsym), details));

                 }

             });

             owntype = checkMethod(site,

                     constructor,

                     diamondResult,

                     localEnv,

                     tree.args,

                     argtypes,

                     typeargtypes,

                     localEnv.info.varArgs).getReturnType();

         }

         return chk.checkClassType(tree.clazz.pos(), owntype, true);

     }

     /** Make an attributed null check tree.

      */

     public JCExpression makeNullCheck(JCExpression arg) {

         // optimization: X.this is never null; skip null check

         Name name = TreeInfo.name(arg);

         if (name == names._this || name == names._super) return arg;

         JCTree.Tag optag = NULLCHK;

         JCUnary tree = make.at(arg.pos).Unary(optag, arg);

         tree.operator = syms.nullcheck;

         tree.type = arg.type;

         return tree;

     }

     public void visitNewArray(JCNewArray tree) {

         Type owntype = types.createErrorType(tree.type);

         Type elemtype;

         if (tree.elemtype != null) {

             elemtype = attribType(tree.elemtype, env);

             chk.validate(tree.elemtype, env);

             owntype = elemtype;

             for (List<JCExpression> l = tree.dims; l.nonEmpty(); l = l.tail) {

                 attribExpr(l.head, env, syms.intType);

                 owntype = new ArrayType(owntype, syms.arrayClass);

             }

         } else {

             // we are seeing an untyped aggregate { ... }

             // this is allowed only if the prototype is an array

             if (pt().tag == ARRAY) {

                 elemtype = types.elemtype(pt());

             } else {

                 if (pt().tag != ERROR) {

                     log.error(tree.pos(), "illegal.initializer.for.type",

                               pt());

                 }

                 elemtype = types.createErrorType(pt());

             }

         }

         if (tree.elems != null) {

             attribExprs(tree.elems, env, elemtype);

             owntype = new ArrayType(elemtype, syms.arrayClass);

         }

         if (!types.isReifiable(elemtype))

             log.error(tree.pos(), "generic.array.creation");

         result = check(tree, owntype, VAL, resultInfo);

     }

     @Override

     public void visitLambda(JCLambda that) {

         throw new UnsupportedOperationException("Lambda expression not supported yet");

     }

     @Override

     public void visitReference(JCMemberReference that) {

         throw new UnsupportedOperationException("Member references not supported yet");

     }

     public void visitParens(JCParens tree) {

         Type owntype = attribTree(tree.expr, env, resultInfo);

         result = check(tree, owntype, pkind(), resultInfo);

         Symbol sym = TreeInfo.symbol(tree);

         if (sym != null && (sym.kind&(TYP|PCK)) != 0)

             log.error(tree.pos(), "illegal.start.of.type");

     }

     public void visitAssign(JCAssign tree) {

         Type owntype = attribTree(tree.lhs, env.dup(tree), varInfo);

         Type capturedType = capture(owntype);

         attribExpr(tree.rhs, env, owntype);

         result = check(tree, capturedType, VAL, resultInfo);

     }

     public void visitAssignop(JCAssignOp tree) {

         // Attribute arguments.

         Type owntype = attribTree(tree.lhs, env, varInfo);

         Type operand = attribExpr(tree.rhs, env);

         // Find operator.

         Symbol operator = tree.operator = rs.resolveBinaryOperator(

             tree.pos(), tree.getTag().noAssignOp(), env,

             owntype, operand);

         if (operator.kind == MTH &&

                 !owntype.isErroneous() &&

                 !operand.isErroneous()) {

             chk.checkOperator(tree.pos(),

                               (OperatorSymbol)operator,

                               tree.getTag().noAssignOp(),

                               owntype,

                               operand);

             chk.checkDivZero(tree.rhs.pos(), operator, operand);

             chk.checkCastable(tree.rhs.pos(),

                               operator.type.getReturnType(),

                               owntype);

         }

         result = check(tree, owntype, VAL, resultInfo);

     }

     public void visitUnary(JCUnary tree) {

         // Attribute arguments.

         Type argtype = (tree.getTag().isIncOrDecUnaryOp())

             ? attribTree(tree.arg, env, varInfo)

             : chk.checkNonVoid(tree.arg.pos(), attribExpr(tree.arg, env));

         // Find operator.

         Symbol operator = tree.operator =

             rs.resolveUnaryOperator(tree.pos(), tree.getTag(), env, argtype);

         Type owntype = types.createErrorType(tree.type);

         if (operator.kind == MTH &&

                 !argtype.isErroneous()) {

             owntype = (tree.getTag().isIncOrDecUnaryOp())

                 ? tree.arg.type

                 : operator.type.getReturnType();

             int opc = ((OperatorSymbol)operator).opcode;

             // If the argument is constant, fold it.

             if (argtype.constValue() != null) {

                 Type ctype = cfolder.fold1(opc, argtype);

                 if (ctype != null) {

                     owntype = cfolder.coerce(ctype, owntype);

                     // Remove constant types from arguments to

                     // conserve space. The parser will fold concatenations

                     // of string literals; the code here also

                     // gets rid of intermediate results when some of the

                     // operands are constant identifiers.

                     if (tree.arg.type.tsym == syms.stringType.tsym) {

                         tree.arg.type = syms.stringType;

                     }

                 }

             }

         }

         result = check(tree, owntype, VAL, resultInfo);

     }

     public void visitBinary(JCBinary tree) {

         // Attribute arguments.

         Type left = chk.checkNonVoid(tree.lhs.pos(), attribExpr(tree.lhs, env));

         Type right = chk.checkNonVoid(tree.lhs.pos(), attribExpr(tree.rhs, env));

         // Find operator.

         Symbol operator = tree.operator =

             rs.resolveBinaryOperator(tree.pos(), tree.getTag(), env, left, right);

         Type owntype = types.createErrorType(tree.type);

         if (operator.kind == MTH &&

                 !left.isErroneous() &&

                 !right.isErroneous()) {

             owntype = operator.type.getReturnType();

             int opc = chk.checkOperator(tree.lhs.pos(),

                                         (OperatorSymbol)operator,

                                         tree.getTag(),

                                         left,

                                         right);

             // If both arguments are constants, fold them.

             if (left.constValue() != null && right.constValue() != null) {

                 Type ctype = cfolder.fold2(opc, left, right);

                 if (ctype != null) {

                     owntype = cfolder.coerce(ctype, owntype);

                     // Remove constant types from arguments to

                     // conserve space. The parser will fold concatenations

                     // of string literals; the code here also

                     // gets rid of intermediate results when some of the

                     // operands are constant identifiers.

                     if (tree.lhs.type.tsym == syms.stringType.tsym) {

                         tree.lhs.type = syms.stringType;

                     }

                     if (tree.rhs.type.tsym == syms.stringType.tsym) {

                         tree.rhs.type = syms.stringType;

                     }

                 }

             }

             // Check that argument types of a reference ==, != are

             // castable to each other, (JLS???).

             if ((opc == ByteCodes.if_acmpeq || opc == ByteCodes.if_acmpne)) {

                 if (!types.isCastable(left, right, new Warner(tree.pos()))) {

                     log.error(tree.pos(), "incomparable.types", left, right);

                 }

             }

             chk.checkDivZero(tree.rhs.pos(), operator, right);

         }

         result = check(tree, owntype, VAL, resultInfo);

     }

     public void visitTypeCast(JCTypeCast tree) {

         Type clazztype = attribType(tree.clazz, env);

         chk.validate(tree.clazz, env, false);

         //a fresh environment is required for 292 inference to work properly ---

         //see Infer.instantiatePolymorphicSignatureInstance()

         Env<AttrContext> localEnv = env.dup(tree);

         Type exprtype = attribExpr(tree.expr, localEnv, Infer.anyPoly);

         Type owntype = chk.checkCastable(tree.expr.pos(), exprtype, clazztype);

         if (exprtype.constValue() != null)

             owntype = cfolder.coerce(exprtype, owntype);

         result = check(tree, capture(owntype), VAL, resultInfo);

         chk.checkRedundantCast(localEnv, tree);

     }

     public void visitTypeTest(JCInstanceOf tree) {

         Type exprtype = chk.checkNullOrRefType(

             tree.expr.pos(), attribExpr(tree.expr, env));

         Type clazztype = chk.checkReifiableReferenceType(

             tree.clazz.pos(), attribType(tree.clazz, env));

         chk.validate(tree.clazz, env, false);

         chk.checkCastable(tree.expr.pos(), exprtype, clazztype);

         result = check(tree, syms.booleanType, VAL, resultInfo);

     }

     public void visitIndexed(JCArrayAccess tree) {

         Type owntype = types.createErrorType(tree.type);

         Type atype = attribExpr(tree.indexed, env);

         attribExpr(tree.index, env, syms.intType);

         if (types.isArray(atype))

             owntype = types.elemtype(atype);

         else if (atype.tag != ERROR)

             log.error(tree.pos(), "array.req.but.found", atype);

         if ((pkind() & VAR) == 0) owntype = capture(owntype);

         result = check(tree, owntype, VAR, resultInfo);

     }

     public void visitIdent(JCIdent tree) {

         Symbol sym;

         boolean varArgs = false;

         // Find symbol

         if (pt().tag == METHOD || pt().tag == FORALL) {

             // If we are looking for a method, the prototype `pt' will be a

             // method type with the type of the call's arguments as parameters.

             env.info.varArgs = false;

             sym = rs.resolveMethod(tree.pos(), env, tree.name, pt().getParameterTypes(), pt().getTypeArguments());

             varArgs = env.info.varArgs;

         } else if (tree.sym != null && tree.sym.kind != VAR) {

             sym = tree.sym;

         } else {

             sym = rs.resolveIdent(tree.pos(), env, tree.name, pkind());

         }

         tree.sym = sym;

         // (1) Also find the environment current for the class where

         //     sym is defined (`symEnv').

         // Only for pre-tiger versions (1.4 and earlier):

         // (2) Also determine whether we access symbol out of an anonymous

         //     class in a this or super call.  This is illegal for instance

         //     members since such classes don't carry a this$n link.

         //     (`noOuterThisPath').

         Env<AttrContext> symEnv = env;

         boolean noOuterThisPath = false;

         if (env.enclClass.sym.owner.kind != PCK && // we are in an inner class

             (sym.kind & (VAR | MTH | TYP)) != 0 &&

             sym.owner.kind == TYP &&

             tree.name != names._this && tree.name != names._super) {

             // Find environment in which identifier is defined.

             while (symEnv.outer != null &&

                    !sym.isMemberOf(symEnv.enclClass.sym, types)) {

                 if ((symEnv.enclClass.sym.flags() & NOOUTERTHIS) != 0)

                     noOuterThisPath = !allowAnonOuterThis;

                 symEnv = symEnv.outer;

             }

         }

         // If symbol is a variable, ...

         if (sym.kind == VAR) {

             VarSymbol v = (VarSymbol)sym;

             // ..., evaluate its initializer, if it has one, and check for

             // illegal forward reference.

             checkInit(tree, env, v, false);

             // If we are expecting a variable (as opposed to a value), check

             // that the variable is assignable in the current environment.

             if (pkind() == VAR)

                 checkAssignable(tree.pos(), v, null, env);

         }

         // In a constructor body,

         // if symbol is a field or instance method, check that it is

         // not accessed before the supertype constructor is called.

         if ((symEnv.info.isSelfCall || noOuterThisPath) &&

             (sym.kind & (VAR | MTH)) != 0 &&

             sym.owner.kind == TYP &&

             (sym.flags() & STATIC) == 0) {

             chk.earlyRefError(tree.pos(), sym.kind == VAR ? sym : thisSym(tree.pos(), env));

         }

         Env<AttrContext> env1 = env;

         if (sym.kind != ERR && sym.kind != TYP && sym.owner != null && sym.owner != env1.enclClass.sym) {

             // If the found symbol is inaccessible, then it is

             // accessed through an enclosing instance.  Locate this

             // enclosing instance:

             while (env1.outer != null && !rs.isAccessible(env, env1.enclClass.sym.type, sym))

                 env1 = env1.outer;

         }

         result = checkId(tree, env1.enclClass.sym.type, sym, env, resultInfo, varArgs);

     }

     public void visitSelect(JCFieldAccess tree) {

         // Determine the expected kind of the qualifier expression.

         int skind = 0;

         if (tree.name == names._this || tree.name == names._super ||

             tree.name == names._class)

         {

             skind = TYP;

         } else {

             if ((pkind() & PCK) != 0) skind = skind | PCK;

             if ((pkind() & TYP) != 0) skind = skind | TYP | PCK;

             if ((pkind() & (VAL | MTH)) != 0) skind = skind | VAL | TYP;

         }

         // Attribute the qualifier expression, and determine its symbol (if any).

         Type site = attribTree(tree.selected, env, new ResultInfo(skind, Infer.anyPoly));

         if ((pkind() & (PCK | TYP)) == 0)

             site = capture(site); // Capture field access

         // don't allow T.class T[].class, etc

         if (skind == TYP) {

             Type elt = site;

             while (elt.tag == ARRAY)

                 elt = ((ArrayType)elt).elemtype;

             if (elt.tag == TYPEVAR) {

                 log.error(tree.pos(), "type.var.cant.be.deref");

                 result = types.createErrorType(tree.type);

                 return;

             }

         }

         // If qualifier symbol is a type or `super', assert `selectSuper'

         // for the selection. This is relevant for determining whether

         // protected symbols are accessible.

         Symbol sitesym = TreeInfo.symbol(tree.selected);

         boolean selectSuperPrev = env.info.selectSuper;

         env.info.selectSuper =

             sitesym != null &&

             sitesym.name == names._super;

         // Determine the symbol represented by the selection.

         env.info.varArgs = false;

         Symbol sym = selectSym(tree, sitesym, site, env, resultInfo);

         if (sym.exists() && !isType(sym) && (pkind() & (PCK | TYP)) != 0) {

             site = capture(site);

             sym = selectSym(tree, sitesym, site, env, resultInfo);

         }

         boolean varArgs = env.info.varArgs;

         tree.sym = sym;

         if (site.tag == TYPEVAR && !isType(sym) && sym.kind != ERR) {

             while (site.tag == TYPEVAR) site = site.getUpperBound();

             site = capture(site);

         }

         // If that symbol is a variable, ...

         if (sym.kind == VAR) {

             VarSymbol v = (VarSymbol)sym;

             // ..., evaluate its initializer, if it has one, and check for

             // illegal forward reference.

             checkInit(tree, env, v, true);

             // If we are expecting a variable (as opposed to a value), check

             // that the variable is assignable in the current environment.

             if (pkind() == VAR)

                 checkAssignable(tree.pos(), v, tree.selected, env);

         }

         if (sitesym != null &&

                 sitesym.kind == VAR &&

                 ((VarSymbol)sitesym).isResourceVariable() &&

                 sym.kind == MTH &&

                 sym.name.equals(names.close) &&

                 sym.overrides(syms.autoCloseableClose, sitesym.type.tsym, types, true) &&

                 env.info.lint.isEnabled(LintCategory.TRY)) {

             log.warning(LintCategory.TRY, tree, "try.explicit.close.call");

         }

         // Disallow selecting a type from an expression

         if (isType(sym) && (sitesym==null || (sitesym.kind&(TYP|PCK)) == 0)) {

             tree.type = check(tree.selected, pt(),

                               sitesym == null ? VAL : sitesym.kind, new ResultInfo(TYP|PCK, pt()));

         }

         if (isType(sitesym)) {

             if (sym.name == names._this) {

                 // If `C' is the currently compiled class, check that

                 // C.this' does not appear in a call to a super(...)

                 if (env.info.isSelfCall &&

                     site.tsym == env.enclClass.sym) {

                     chk.earlyRefError(tree.pos(), sym);

                 }

             } else {

                 // Check if type-qualified fields or methods are static (JLS)

                 if ((sym.flags() & STATIC) == 0 &&

                     sym.name != names._super &&

                     (sym.kind == VAR || sym.kind == MTH)) {

                     rs.access(rs.new StaticError(sym),

                               tree.pos(), site, sym.name, true);

                 }

             }

         } else if (sym.kind != ERR && (sym.flags() & STATIC) != 0 && sym.name != names._class) {

             // If the qualified item is not a type and the selected item is static, report

             // a warning. Make allowance for the class of an array type e.g. Object[].class)

             chk.warnStatic(tree, "static.not.qualified.by.type", Kinds.kindName(sym.kind), sym.owner);

         }

         // If we are selecting an instance member via a `super', ...

         if (env.info.selectSuper && (sym.flags() & STATIC) == 0) {

             // Check that super-qualified symbols are not abstract (JLS)

             rs.checkNonAbstract(tree.pos(), sym);

             if (site.isRaw()) {

                 // Determine argument types for site.

                 Type site1 = types.asSuper(env.enclClass.sym.type, site.tsym);

                 if (site1 != null) site = site1;

             }

         }

         env.info.selectSuper = selectSuperPrev;

         result = checkId(tree, site, sym, env, resultInfo, varArgs);

     }

     //where

         /** Determine symbol referenced by a Select expression,

          *

          *  @param tree   The select tree.

          *  @param site   The type of the selected expression,

          *  @param env    The current environment.

          *  @param resultInfo The current result.

          */

         private Symbol selectSym(JCFieldAccess tree,

                                  Symbol location,

                                  Type site,

                                  Env<AttrContext> env,

                                  ResultInfo resultInfo) {

             DiagnosticPosition pos = tree.pos();

             Name name = tree.name;

             switch (site.tag) {

             case PACKAGE:

                 return rs.access(

                     rs.findIdentInPackage(env, site.tsym, name, resultInfo.pkind),

                     pos, location, site, name, true);

             case ARRAY:

             case CLASS:

                 if (resultInfo.pt.tag == METHOD || resultInfo.pt.tag == FORALL) {

                     return rs.resolveQualifiedMethod(

                         pos, env, location, site, name, resultInfo.pt.getParameterTypes(), resultInfo.pt.getTypeArguments());

                 } else if (name == names._this || name == names._super) {

                     return rs.resolveSelf(pos, env, site.tsym, name);

                 } else if (name == names._class) {

                     // In this case, we have already made sure in

                     // visitSelect that qualifier expression is a type.

                     Type t = syms.classType;

                     List<Type> typeargs = allowGenerics

                         ? List.of(types.erasure(site))

                         : List.<Type>nil();

                     t = new ClassType(t.getEnclosingType(), typeargs, t.tsym);

                     return new VarSymbol(

                         STATIC | PUBLIC | FINAL, names._class, t, site.tsym);

                 } else {

                     // We are seeing a plain identifier as selector.

                     Symbol sym = rs.findIdentInType(env, site, name, resultInfo.pkind);

                     if ((resultInfo.pkind & ERRONEOUS) == 0)

                         sym = rs.access(sym, pos, location, site, name, true);

                     return sym;

                 }

             case WILDCARD:

                 throw new AssertionError(tree);

             case TYPEVAR:

                 // Normally, site.getUpperBound() shouldn't be null.

                 // It should only happen during memberEnter/attribBase

                 // when determining the super type which *must* beac

                 // done before attributing the type variables.  In

                 // other words, we are seeing this illegal program:

                 // class B<T> extends A<T.foo> {}

                 Symbol sym = (site.getUpperBound() != null)

                     ? selectSym(tree, location, capture(site.getUpperBound()), env, resultInfo)

                     : null;

                 if (sym == null) {

                     log.error(pos, "type.var.cant.be.deref");

                     return syms.errSymbol;

                 } else {

                     Symbol sym2 = (sym.flags() & Flags.PRIVATE) != 0 ?

                         rs.new AccessError(env, site, sym) :

                                 sym;

                     rs.access(sym2, pos, location, site, name, true);

                     return sym;

                 }

             case ERROR:

                 // preserve identifier names through errors

                 return types.createErrorType(name, site.tsym, site).tsym;

             default:

                 // The qualifier expression is of a primitive type -- only

                 // .class is allowed for these.

                 if (name == names._class) {

                     // In this case, we have already made sure in Select that

                     // qualifier expression is a type.

                     Type t = syms.classType;

                     Type arg = types.boxedClass(site).type;

                     t = new ClassType(t.getEnclosingType(), List.of(arg), t.tsym);

                     return new VarSymbol(

                         STATIC | PUBLIC | FINAL, names._class, t, site.tsym);

                 } else {

                     log.error(pos, "cant.deref", site);

                     return syms.errSymbol;

                 }

             }

         }

         /** Determine type of identifier or select expression and check that

          *  (1) the referenced symbol is not deprecated

          *  (2) the symbol's type is safe (@see checkSafe)

          *  (3) if symbol is a variable, check that its type and kind are

          *      compatible with the prototype and protokind.

          *  (4) if symbol is an instance field of a raw type,

          *      which is being assigned to, issue an unchecked warning if its

          *      type changes under erasure.

          *  (5) if symbol is an instance method of a raw type, issue an

          *      unchecked warning if its argument types change under erasure.

          *  If checks succeed:

          *    If symbol is a constant, return its constant type

          *    else if symbol is a method, return its result type

          *    otherwise return its type.

          *  Otherwise return errType.

          *

          *  @param tree       The syntax tree representing the identifier

          *  @param site       If this is a select, the type of the selected

          *                    expression, otherwise the type of the current class.

          *  @param sym        The symbol representing the identifier.

          *  @param env        The current environment.

          *  @param resultInfo    The expected result

          */

         Type checkId(JCTree tree,

                      Type site,

                      Symbol sym,

                      Env<AttrContext> env,

                      ResultInfo resultInfo,

                      boolean useVarargs) {

             if (resultInfo.pt.isErroneous()) return types.createErrorType(site);

             Type owntype; // The computed type of this identifier occurrence.

             switch (sym.kind) {

             case TYP:

                 // For types, the computed type equals the symbol's type,

                 // except for two situations:

                 owntype = sym.type;

                 if (owntype.tag == CLASS) {

                     Type ownOuter = owntype.getEnclosingType();

                     // (a) If the symbol's type is parameterized, erase it

                     // because no type parameters were given.

                     // We recover generic outer type later in visitTypeApply.

                     if (owntype.tsym.type.getTypeArguments().nonEmpty()) {

                         owntype = types.erasure(owntype);

                     }

                     // (b) If the symbol's type is an inner class, then

                     // we have to interpret its outer type as a superclass

                     // of the site type. Example:

                     //

                     // class Tree<A> { class Visitor { ... } }

                     // class PointTree extends Tree<Point> { ... }

                     // ...PointTree.Visitor...

                     //

                     // Then the type of the last expression above is

                     // Tree<Point>.Visitor.

                     else if (ownOuter.tag == CLASS && site != ownOuter) {

                         Type normOuter = site;

                         if (normOuter.tag == CLASS)

                             normOuter = types.asEnclosingSuper(site, ownOuter.tsym);

                         if (normOuter == null) // perhaps from an import

                             normOuter = types.erasure(ownOuter);

                         if (normOuter != ownOuter)

                             owntype = new ClassType(

                                 normOuter, List.<Type>nil(), owntype.tsym);

                     }

                 }

                 break;

             case VAR:

                 VarSymbol v = (VarSymbol)sym;

                 // Test (4): if symbol is an instance field of a raw type,

                 // which is being assigned to, issue an unchecked warning if

                 // its type changes under erasure.

                 if (allowGenerics &&

                     resultInfo.pkind == VAR &&

                     v.owner.kind == TYP &&

                     (v.flags() & STATIC) == 0 &&

                     (site.tag == CLASS || site.tag == TYPEVAR)) {

                     Type s = types.asOuterSuper(site, v.owner);

                     if (s != null &&

                         s.isRaw() &&

                         !types.isSameType(v.type, v.erasure(types))) {

                         chk.warnUnchecked(tree.pos(),

                                           "unchecked.assign.to.var",

                                           v, s);

                     }

                 }

                 // The computed type of a variable is the type of the

                 // variable symbol, taken as a member of the site type.

                 owntype = (sym.owner.kind == TYP &&

                            sym.name != names._this && sym.name != names._super)

                     ? types.memberType(site, sym)

                     : sym.type;

                 // If the variable is a constant, record constant value in

                 // computed type.

                 if (v.getConstValue() != null && isStaticReference(tree))

                     owntype = owntype.constType(v.getConstValue());

                 if (resultInfo.pkind == VAL) {

                     owntype = capture(owntype); // capture "names as expressions"

                 }

                 break;

             case MTH: {

                 JCMethodInvocation app = (JCMethodInvocation)env.tree;

                 owntype = checkMethod(site, sym,

                         new ResultInfo(VAL, resultInfo.pt.getReturnType(), resultInfo.checkContext),

                         env, app.args, resultInfo.pt.getParameterTypes(),

                         resultInfo.pt.getTypeArguments(), env.info.varArgs);

                 break;

             }

             case PCK: case ERR:

                 owntype = sym.type;

                 break;

             default:

                 throw new AssertionError("unexpected kind: " + sym.kind +

                                          " in tree " + tree);

             }

             // Test (1): emit a `deprecation' warning if symbol is deprecated.

             // (for constructors, the error was given when the constructor was

             // resolved)

             if (sym.name != names.init) {

                 chk.checkDeprecated(tree.pos(), env.info.scope.owner, sym);

                 chk.checkSunAPI(tree.pos(), sym);

             }

             // Test (3): if symbol is a variable, check that its type and

             // kind are compatible with the prototype and protokind.

             return check(tree, owntype, sym.kind, resultInfo);

         }

         /** Check that variable is initialized and evaluate the variable's

          *  initializer, if not yet done. Also check that variable is not

          *  referenced before it is defined.

          *  @param tree    The tree making up the variable reference.

          *  @param env     The current environment.

          *  @param v       The variable's symbol.

          */

         private void checkInit(JCTree tree,

                                Env<AttrContext> env,

                                VarSymbol v,

                                boolean onlyWarning) {

 //          System.err.println(v + " " + ((v.flags() & STATIC) != 0) + " " +

 //                             tree.pos + " " + v.pos + " " +

 //                             Resolve.isStatic(env));//DEBUG

             // A forward reference is diagnosed if the declaration position

             // of the variable is greater than the current tree position

             // and the tree and variable definition occur in the same class

             // definition.  Note that writes don't count as references.

             // This check applies only to class and instance

             // variables.  Local variables follow different scope rules,

             // and are subject to definite assignment checking.

             if ((env.info.enclVar == v || v.pos > tree.pos) &&

                 v.owner.kind == TYP &&

                 canOwnInitializer(owner(env)) &&

                 v.owner == env.info.scope.owner.enclClass() &&

                 ((v.flags() & STATIC) != 0) == Resolve.isStatic(env) &&

                 (!env.tree.hasTag(ASSIGN) ||

                  TreeInfo.skipParens(((JCAssign) env.tree).lhs) != tree)) {

                 String suffix = (env.info.enclVar == v) ?

                                 "self.ref" : "forward.ref";

                 if (!onlyWarning || isStaticEnumField(v)) {

                     log.error(tree.pos(), "illegal." + suffix);

                 } else if (useBeforeDeclarationWarning) {

                     log.warning(tree.pos(), suffix, v);

                 }

             }

             v.getConstValue(); // ensure initializer is evaluated

             checkEnumInitializer(tree, env, v);

         }

         /**

          * Check for illegal references to static members of enum.  In

          * an enum type, constructors and initializers may not

          * reference its static members unless they are constant.

          *

          * @param tree    The tree making up the variable reference.

          * @param env     The current environment.

          * @param v       The variable's symbol.

          * @jls  section 8.9 Enums