jdk8-mips64-public/langtools: src/share/classes/com/sun/tools/javac/comp/Attr.java@e5cf1569d3a4 (annotated)

src/share/classes/com/sun/tools/javac/comp/Attr.java@e5cf1569d3a4 (annotated)

src/share/classes/com/sun/tools/javac/comp/Attr.java

Thu, 02 Aug 2012 18:23:21 +0100

author: mcimadamore
date: Thu, 02 Aug 2012 18:23:21 +0100
changeset 1297: e5cf1569d3a4
parent 1296: cddc2c894cc6
child 1313: 873ddd9f4900
permissions: -rw-r--r--

7175538: Integrate efectively final check with DA/DU analysis
Summary: Allow generalized effectively-final analysis for all local variables
Reviewed-by: jjg, dlsmith

 /*
  * 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
          */
         private void checkEnumInitializer(JCTree tree, Env<AttrContext> env, VarSymbol v) {
             // JLS:
             //
             // "It is a compile-time error to reference a static field
             // of an enum type that is not a compile-time constant
             // (15.28) from constructors, instance initializer blocks,
             // or instance variable initializer expressions of that
             // type. It is a compile-time error for the constructors,
             // instance initializer blocks, or instance variable
             // initializer expressions of an enum constant e to refer
             // to itself or to an enum constant of the same type that
             // is declared to the right of e."
             if (isStaticEnumField(v)) {
                 ClassSymbol enclClass = env.info.scope.owner.enclClass();
                 if (enclClass == null || enclClass.owner == null)
                     return;
                 // See if the enclosing class is the enum (or a
                 // subclass thereof) declaring v.  If not, this
                 // reference is OK.
                 if (v.owner != enclClass && !types.isSubtype(enclClass.type, v.owner.type))
                     return;
                 // If the reference isn't from an initializer, then
                 // the reference is OK.
                 if (!Resolve.isInitializer(env))
                     return;
                 log.error(tree.pos(), "illegal.enum.static.ref");
             }
         }
         /** Is the given symbol a static, non-constant field of an Enum?
          *  Note: enum literals should not be regarded as such
          */
         private boolean isStaticEnumField(VarSymbol v) {
             return Flags.isEnum(v.owner) &&
                    Flags.isStatic(v) &&
                    !Flags.isConstant(v) &&
                    v.name != names._class;
         }
         /** Can the given symbol be the owner of code which forms part
          *  if class initialization? This is the case if the symbol is
          *  a type or field, or if the symbol is the synthetic method.
          *  owning a block.
          */
         private boolean canOwnInitializer(Symbol sym) {
             return
                 (sym.kind & (VAR | TYP)) != 0 ||
                 (sym.kind == MTH && (sym.flags() & BLOCK) != 0);
         }
     Warner noteWarner = new Warner();
     /**
      * Check that method arguments conform to its instantiation.
      **/
     public Type checkMethod(Type site,
                             Symbol sym,
                             ResultInfo resultInfo,
                             Env<AttrContext> env,
                             final List<JCExpression> argtrees,
                             List<Type> argtypes,
                             List<Type> typeargtypes,
                             boolean useVarargs) {
         // Test (5): if symbol is an instance method of a raw type, issue
         // an unchecked warning if its argument types change under erasure.
         if (allowGenerics &&
             (sym.flags() & STATIC) == 0 &&
             (site.tag == CLASS || site.tag == TYPEVAR)) {
             Type s = types.asOuterSuper(site, sym.owner);
             if (s != null && s.isRaw() &&
                 !types.isSameTypes(sym.type.getParameterTypes(),
                                    sym.erasure(types).getParameterTypes())) {
                 chk.warnUnchecked(env.tree.pos(),
                                   "unchecked.call.mbr.of.raw.type",
                                   sym, s);
             }
         }
         // Compute the identifier's instantiated type.
         // For methods, we need to compute the instance type by
         // Resolve.instantiate from the symbol's type as well as
         // any type arguments and value arguments.
         noteWarner.clear();
         try {
             Type owntype = rs.rawInstantiate(
                     env,
                     site,
                     sym,
                     resultInfo,
                     argtypes,
                     typeargtypes,
                     allowBoxing,
                     useVarargs,
                     noteWarner);
             return chk.checkMethod(owntype, sym, env, argtrees, argtypes, useVarargs,
                     noteWarner.hasNonSilentLint(LintCategory.UNCHECKED));
         } catch (Infer.InferenceException ex) {
             //invalid target type - propagate exception outwards or report error
             //depending on the current check context
             resultInfo.checkContext.report(env.tree.pos(), ex.getDiagnostic());
             return types.createErrorType(site);
         } catch (Resolve.InapplicableMethodException ex) {
             Assert.error();
             return null;
         }
     }
     /**
      * Check that constructor arguments conform to its instantiation.
      **/
     public Type checkConstructor(Type site,
                             Symbol sym,
                             Env<AttrContext> env,
                             final List<JCExpression> argtrees,
                             List<Type> argtypes,
                             List<Type> typeargtypes,
                             boolean useVarargs) {
         Type owntype = checkMethod(site, sym, new ResultInfo(VAL, syms.voidType), env, argtrees, argtypes, typeargtypes, useVarargs);
         chk.checkType(env.tree.pos(), owntype.getReturnType(), syms.voidType);
         return owntype;
     }
     public void visitLiteral(JCLiteral tree) {
         result = check(
             tree, litType(tree.typetag).constType(tree.value), VAL, resultInfo);
     }
     //where
     /** Return the type of a literal with given type tag.
      */
     Type litType(int tag) {
         return (tag == TypeTags.CLASS) ? syms.stringType : syms.typeOfTag[tag];
     }
     public void visitTypeIdent(JCPrimitiveTypeTree tree) {
         result = check(tree, syms.typeOfTag[tree.typetag], TYP, resultInfo);
     }
     public void visitTypeArray(JCArrayTypeTree tree) {
         Type etype = attribType(tree.elemtype, env);
         Type type = new ArrayType(etype, syms.arrayClass);
         result = check(tree, type, TYP, resultInfo);
     }
     /** Visitor method for parameterized types.
      *  Bound checking is left until later, since types are attributed
      *  before supertype structure is completely known
      */
     public void visitTypeApply(JCTypeApply tree) {
         Type owntype = types.createErrorType(tree.type);
         // Attribute functor part of application and make sure it's a class.
         Type clazztype = chk.checkClassType(tree.clazz.pos(), attribType(tree.clazz, env));
         // Attribute type parameters
         List<Type> actuals = attribTypes(tree.arguments, env);
         if (clazztype.tag == CLASS) {
             List<Type> formals = clazztype.tsym.type.getTypeArguments();
             if (actuals.isEmpty()) //diamond
                 actuals = formals;
             if (actuals.length() == formals.length()) {
                 List<Type> a = actuals;
                 List<Type> f = formals;
                 while (a.nonEmpty()) {
                     a.head = a.head.withTypeVar(f.head);
                     a = a.tail;
                     f = f.tail;
                 }
                 // Compute the proper generic outer
                 Type clazzOuter = clazztype.getEnclosingType();
                 if (clazzOuter.tag == CLASS) {
                     Type site;
                     JCExpression clazz = TreeInfo.typeIn(tree.clazz);
                     if (clazz.hasTag(IDENT)) {
                         site = env.enclClass.sym.type;
                     } else if (clazz.hasTag(SELECT)) {
                         site = ((JCFieldAccess) clazz).selected.type;
                     } else throw new AssertionError(""+tree);
                     if (clazzOuter.tag == CLASS && site != clazzOuter) {
                         if (site.tag == CLASS)
                             site = types.asOuterSuper(site, clazzOuter.tsym);
                         if (site == null)
                             site = types.erasure(clazzOuter);
                         clazzOuter = site;
                     }
                 }
                 owntype = new ClassType(clazzOuter, actuals, clazztype.tsym);
             } else {
                 if (formals.length() != 0) {
                     log.error(tree.pos(), "wrong.number.type.args",
                               Integer.toString(formals.length()));
                 } else {
                     log.error(tree.pos(), "type.doesnt.take.params", clazztype.tsym);
                 }
                 owntype = types.createErrorType(tree.type);
             }
         }
         result = check(tree, owntype, TYP, resultInfo);
     }
     public void visitTypeUnion(JCTypeUnion tree) {
         ListBuffer<Type> multicatchTypes = ListBuffer.lb();
         ListBuffer<Type> all_multicatchTypes = null; // lazy, only if needed
         for (JCExpression typeTree : tree.alternatives) {
             Type ctype = attribType(typeTree, env);
             ctype = chk.checkType(typeTree.pos(),
                           chk.checkClassType(typeTree.pos(), ctype),
                           syms.throwableType);
             if (!ctype.isErroneous()) {
                 //check that alternatives of a union type are pairwise
                 //unrelated w.r.t. subtyping
                 if (chk.intersects(ctype,  multicatchTypes.toList())) {
                     for (Type t : multicatchTypes) {
                         boolean sub = types.isSubtype(ctype, t);
                         boolean sup = types.isSubtype(t, ctype);
                         if (sub || sup) {
                             //assume 'a' <: 'b'
                             Type a = sub ? ctype : t;
                             Type b = sub ? t : ctype;
                             log.error(typeTree.pos(), "multicatch.types.must.be.disjoint", a, b);
                         }
                     }
                 }
                 multicatchTypes.append(ctype);
                 if (all_multicatchTypes != null)
                     all_multicatchTypes.append(ctype);
             } else {
                 if (all_multicatchTypes == null) {
                     all_multicatchTypes = ListBuffer.lb();
                     all_multicatchTypes.appendList(multicatchTypes);
                 }
                 all_multicatchTypes.append(ctype);
             }
         }
         Type t = check(tree, types.lub(multicatchTypes.toList()), TYP, resultInfo);
         if (t.tag == CLASS) {
             List<Type> alternatives =
                 ((all_multicatchTypes == null) ? multicatchTypes : all_multicatchTypes).toList();
             t = new UnionClassType((ClassType) t, alternatives);
         }
         tree.type = result = t;
     }
     public void visitTypeParameter(JCTypeParameter tree) {
         TypeVar a = (TypeVar)tree.type;
         Set<Type> boundSet = new HashSet<Type>();
         if (a.bound.isErroneous())
             return;
         List<Type> bs = types.getBounds(a);
         if (tree.bounds.nonEmpty()) {
             // accept class or interface or typevar as first bound.
             Type b = checkBase(bs.head, tree.bounds.head, env, false, false, false);
             boundSet.add(types.erasure(b));
             if (b.isErroneous()) {
                 a.bound = b;
             }
             else if (b.tag == TYPEVAR) {
                 // if first bound was a typevar, do not accept further bounds.
                 if (tree.bounds.tail.nonEmpty()) {
                     log.error(tree.bounds.tail.head.pos(),
                               "type.var.may.not.be.followed.by.other.bounds");
                     tree.bounds = List.of(tree.bounds.head);
                     a.bound = bs.head;
                 }
             } else {
                 // if first bound was a class or interface, accept only interfaces
                 // as further bounds.
                 for (JCExpression bound : tree.bounds.tail) {
                     bs = bs.tail;
                     Type i = checkBase(bs.head, bound, env, false, true, false);
                     if (i.isErroneous())
                         a.bound = i;
                     else if (i.tag == CLASS)
                         chk.checkNotRepeated(bound.pos(), types.erasure(i), boundSet);
                 }
             }
         }
         bs = types.getBounds(a);
         // in case of multiple bounds ...
         if (bs.length() > 1) {
             // ... the variable's bound is a class type flagged COMPOUND
             // (see comment for TypeVar.bound).
             // In this case, generate a class tree that represents the
             // bound class, ...
             JCExpression extending;
             List<JCExpression> implementing;
             if ((bs.head.tsym.flags() & INTERFACE) == 0) {
                 extending = tree.bounds.head;
                 implementing = tree.bounds.tail;
             } else {
                 extending = null;
                 implementing = tree.bounds;
             }
             JCClassDecl cd = make.at(tree.pos).ClassDef(
                 make.Modifiers(PUBLIC | ABSTRACT),
                 tree.name, List.<JCTypeParameter>nil(),
                 extending, implementing, List.<JCTree>nil());
             ClassSymbol c = (ClassSymbol)a.getUpperBound().tsym;
             Assert.check((c.flags() & COMPOUND) != 0);
             cd.sym = c;
             c.sourcefile = env.toplevel.sourcefile;
             // ... and attribute the bound class
             c.flags_field |= UNATTRIBUTED;
             Env<AttrContext> cenv = enter.classEnv(cd, env);
             enter.typeEnvs.put(c, cenv);
         }
     }
     public void visitWildcard(JCWildcard tree) {
         //- System.err.println("visitWildcard("+tree+");");//DEBUG
         Type type = (tree.kind.kind == BoundKind.UNBOUND)
             ? syms.objectType
             : attribType(tree.inner, env);
         result = check(tree, new WildcardType(chk.checkRefType(tree.pos(), type),
                                               tree.kind.kind,
                                               syms.boundClass),
                        TYP, resultInfo);
     }
     public void visitAnnotation(JCAnnotation tree) {
         log.error(tree.pos(), "annotation.not.valid.for.type", pt());
         result = tree.type = syms.errType;
     }
     public void visitErroneous(JCErroneous tree) {
         if (tree.errs != null)
             for (JCTree err : tree.errs)
                 attribTree(err, env, new ResultInfo(ERR, pt()));
         result = tree.type = syms.errType;
     }
     /** Default visitor method for all other trees.
      */
     public void visitTree(JCTree tree) {
         throw new AssertionError();
     }
     /**
      * Attribute an env for either a top level tree or class declaration.
      */
     public void attrib(Env<AttrContext> env) {
         if (env.tree.hasTag(TOPLEVEL))
             attribTopLevel(env);
         else
             attribClass(env.tree.pos(), env.enclClass.sym);
     }
     /**
      * Attribute a top level tree. These trees are encountered when the
      * package declaration has annotations.
      */
     public void attribTopLevel(Env<AttrContext> env) {
         JCCompilationUnit toplevel = env.toplevel;
         try {
             annotate.flush();
             chk.validateAnnotations(toplevel.packageAnnotations, toplevel.packge);
         } catch (CompletionFailure ex) {
             chk.completionError(toplevel.pos(), ex);
         }
     }
     /** Main method: attribute class definition associated with given class symbol.
      *  reporting completion failures at the given position.
      *  @param pos The source position at which completion errors are to be
      *             reported.
      *  @param c   The class symbol whose definition will be attributed.
      */
     public void attribClass(DiagnosticPosition pos, ClassSymbol c) {
         try {
             annotate.flush();
             attribClass(c);
         } catch (CompletionFailure ex) {
             chk.completionError(pos, ex);
         }
     }
     /** Attribute class definition associated with given class symbol.
      *  @param c   The class symbol whose definition will be attributed.
      */
     void attribClass(ClassSymbol c) throws CompletionFailure {
         if (c.type.tag == ERROR) return;
         // Check for cycles in the inheritance graph, which can arise from
         // ill-formed class files.
         chk.checkNonCyclic(null, c.type);
         Type st = types.supertype(c.type);
         if ((c.flags_field & Flags.COMPOUND) == 0) {
             // First, attribute superclass.
             if (st.tag == CLASS)
                 attribClass((ClassSymbol)st.tsym);
             // Next attribute owner, if it is a class.
             if (c.owner.kind == TYP && c.owner.type.tag == CLASS)
                 attribClass((ClassSymbol)c.owner);
         }
         // The previous operations might have attributed the current class
         // if there was a cycle. So we test first whether the class is still
         // UNATTRIBUTED.
         if ((c.flags_field & UNATTRIBUTED) != 0) {
             c.flags_field &= ~UNATTRIBUTED;
             // Get environment current at the point of class definition.
             Env<AttrContext> env = enter.typeEnvs.get(c);
             // The info.lint field in the envs stored in enter.typeEnvs is deliberately uninitialized,
             // because the annotations were not available at the time the env was created. Therefore,
             // we look up the environment chain for the first enclosing environment for which the
             // lint value is set. Typically, this is the parent env, but might be further if there
             // are any envs created as a result of TypeParameter nodes.
             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
             env.info.lint = lintEnv.info.lint.augment(c.attributes_field, c.flags());
             Lint prevLint = chk.setLint(env.info.lint);
             JavaFileObject prev = log.useSource(c.sourcefile);
             try {
                 // java.lang.Enum may not be subclassed by a non-enum
                 if (st.tsym == syms.enumSym &&
                     ((c.flags_field & (Flags.ENUM|Flags.COMPOUND)) == 0))
                     log.error(env.tree.pos(), "enum.no.subclassing");
                 // Enums may not be extended by source-level classes
                 if (st.tsym != null &&
                     ((st.tsym.flags_field & Flags.ENUM) != 0) &&
                     ((c.flags_field & (Flags.ENUM | Flags.COMPOUND)) == 0) &&
                     !target.compilerBootstrap(c)) {
                     log.error(env.tree.pos(), "enum.types.not.extensible");
                 }
                 attribClassBody(env, c);
                 chk.checkDeprecatedAnnotation(env.tree.pos(), c);
             } finally {
                 log.useSource(prev);
                 chk.setLint(prevLint);
             }
         }
     }
     public void visitImport(JCImport tree) {
         // nothing to do
     }
     /** Finish the attribution of a class. */
     private void attribClassBody(Env<AttrContext> env, ClassSymbol c) {
         JCClassDecl tree = (JCClassDecl)env.tree;
         Assert.check(c == tree.sym);
         // Validate annotations
         chk.validateAnnotations(tree.mods.annotations, c);
         // Validate type parameters, supertype and interfaces.
         attribBounds(tree.typarams);
         if (!c.isAnonymous()) {
             //already checked if anonymous
             chk.validate(tree.typarams, env);
             chk.validate(tree.extending, env);
             chk.validate(tree.implementing, env);
         }
         // If this is a non-abstract class, check that it has no abstract
         // methods or unimplemented methods of an implemented interface.
         if ((c.flags() & (ABSTRACT | INTERFACE)) == 0) {
             if (!relax)
                 chk.checkAllDefined(tree.pos(), c);
         }
         if ((c.flags() & ANNOTATION) != 0) {
             if (tree.implementing.nonEmpty())
                 log.error(tree.implementing.head.pos(),
                           "cant.extend.intf.annotation");
             if (tree.typarams.nonEmpty())
                 log.error(tree.typarams.head.pos(),
                           "intf.annotation.cant.have.type.params");
         } else {
             // Check that all extended classes and interfaces
             // are compatible (i.e. no two define methods with same arguments
             // yet different return types).  (JLS 8.4.6.3)
             chk.checkCompatibleSupertypes(tree.pos(), c.type);
         }
         // Check that class does not import the same parameterized interface
         // with two different argument lists.
         chk.checkClassBounds(tree.pos(), c.type);
         tree.type = c.type;
         for (List<JCTypeParameter> l = tree.typarams;
              l.nonEmpty(); l = l.tail) {
              Assert.checkNonNull(env.info.scope.lookup(l.head.name).scope);
         }
         // Check that a generic class doesn't extend Throwable
         if (!c.type.allparams().isEmpty() && types.isSubtype(c.type, syms.throwableType))
             log.error(tree.extending.pos(), "generic.throwable");
         // Check that all methods which implement some
         // method conform to the method they implement.
         chk.checkImplementations(tree);
         //check that a resource implementing AutoCloseable cannot throw InterruptedException
         checkAutoCloseable(tree.pos(), env, c.type);
         for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
             // Attribute declaration
             attribStat(l.head, env);
             // Check that declarations in inner classes are not static (JLS 8.1.2)
             // Make an exception for static constants.
             if (c.owner.kind != PCK &&
                 ((c.flags() & STATIC) == 0 || c.name == names.empty) &&
                 (TreeInfo.flags(l.head) & (STATIC | INTERFACE)) != 0) {
                 Symbol sym = null;
                 if (l.head.hasTag(VARDEF)) sym = ((JCVariableDecl) l.head).sym;
                 if (sym == null ||
                     sym.kind != VAR ||
                     ((VarSymbol) sym).getConstValue() == null)
                     log.error(l.head.pos(), "icls.cant.have.static.decl", c);
             }
         }
         // Check for cycles among non-initial constructors.
         chk.checkCyclicConstructors(tree);
         // Check for cycles among annotation elements.
         chk.checkNonCyclicElements(tree);
         // Check for proper use of serialVersionUID
         if (env.info.lint.isEnabled(LintCategory.SERIAL) &&
             isSerializable(c) &&
             (c.flags() & Flags.ENUM) == 0 &&
             (c.flags() & ABSTRACT) == 0) {
             checkSerialVersionUID(tree, c);
         }
     }
         // where
         /** check if a class is a subtype of Serializable, if that is available. */
         private boolean isSerializable(ClassSymbol c) {
             try {
                 syms.serializableType.complete();
             }
             catch (CompletionFailure e) {
                 return false;
             }
             return types.isSubtype(c.type, syms.serializableType);
         }
         /** Check that an appropriate serialVersionUID member is defined. */
         private void checkSerialVersionUID(JCClassDecl tree, ClassSymbol c) {
             // check for presence of serialVersionUID
             Scope.Entry e = c.members().lookup(names.serialVersionUID);
             while (e.scope != null && e.sym.kind != VAR) e = e.next();
             if (e.scope == null) {
                 log.warning(LintCategory.SERIAL,
                         tree.pos(), "missing.SVUID", c);
                 return;
             }
             // check that it is static final
             VarSymbol svuid = (VarSymbol)e.sym;
             if ((svuid.flags() & (STATIC | FINAL)) !=
                 (STATIC | FINAL))
                 log.warning(LintCategory.SERIAL,
                         TreeInfo.diagnosticPositionFor(svuid, tree), "improper.SVUID", c);
             // check that it is long
             else if (svuid.type.tag != TypeTags.LONG)
                 log.warning(LintCategory.SERIAL,
                         TreeInfo.diagnosticPositionFor(svuid, tree), "long.SVUID", c);
             // check constant
             else if (svuid.getConstValue() == null)
                 log.warning(LintCategory.SERIAL,
                         TreeInfo.diagnosticPositionFor(svuid, tree), "constant.SVUID", c);
         }
     private Type capture(Type type) {
         return types.capture(type);
     }
     // <editor-fold desc="post-attribution visitor">
     /**
      * Handle missing types/symbols in an AST. This routine is useful when
      * the compiler has encountered some errors (which might have ended up
      * terminating attribution abruptly); if the compiler is used in fail-over
      * mode (e.g. by an IDE) and the AST contains semantic errors, this routine
      * prevents NPE to be progagated during subsequent compilation steps.
      */
     public void postAttr(Env<AttrContext> env) {
         new PostAttrAnalyzer().scan(env.tree);
     }
     class PostAttrAnalyzer extends TreeScanner {
         private void initTypeIfNeeded(JCTree that) {
             if (that.type == null) {
                 that.type = syms.unknownType;
             }
         }
         @Override
         public void scan(JCTree tree) {
             if (tree == null) return;
             if (tree instanceof JCExpression) {
                 initTypeIfNeeded(tree);
             }
             super.scan(tree);
         }
         @Override
         public void visitIdent(JCIdent that) {
             if (that.sym == null) {
                 that.sym = syms.unknownSymbol;
             }
         }
         @Override
         public void visitSelect(JCFieldAccess that) {
             if (that.sym == null) {
                 that.sym = syms.unknownSymbol;
             }
             super.visitSelect(that);
         }
         @Override
         public void visitClassDef(JCClassDecl that) {
             initTypeIfNeeded(that);
             if (that.sym == null) {
                 that.sym = new ClassSymbol(0, that.name, that.type, syms.noSymbol);
             }
             super.visitClassDef(that);
         }
         @Override
         public void visitMethodDef(JCMethodDecl that) {
             initTypeIfNeeded(that);
             if (that.sym == null) {
                 that.sym = new MethodSymbol(0, that.name, that.type, syms.noSymbol);
             }
             super.visitMethodDef(that);
         }
         @Override
         public void visitVarDef(JCVariableDecl that) {
             initTypeIfNeeded(that);
             if (that.sym == null) {
                 that.sym = new VarSymbol(0, that.name, that.type, syms.noSymbol);
                 that.sym.adr = 0;
             }
             super.visitVarDef(that);
         }
         @Override
         public void visitNewClass(JCNewClass that) {
             if (that.constructor == null) {
                 that.constructor = new MethodSymbol(0, names.init, syms.unknownType, syms.noSymbol);
             }
             if (that.constructorType == null) {
                 that.constructorType = syms.unknownType;
             }
             super.visitNewClass(that);
         }
         @Override
         public void visitAssignop(JCAssignOp that) {
             if (that.operator == null)
                 that.operator = new OperatorSymbol(names.empty, syms.unknownType, -1, syms.noSymbol);
             super.visitAssignop(that);
         }
         @Override
         public void visitBinary(JCBinary that) {
             if (that.operator == null)
                 that.operator = new OperatorSymbol(names.empty, syms.unknownType, -1, syms.noSymbol);
             super.visitBinary(that);
         }
         @Override
         public void visitUnary(JCUnary that) {
             if (that.operator == null)
                 that.operator = new OperatorSymbol(names.empty, syms.unknownType, -1, syms.noSymbol);
             super.visitUnary(that);
         }
     }
     // </editor-fold>
 }

Mercurial > jdk8-mips64-public > langtools / annotate

src/share/classes/com/sun/tools/javac/comp/Attr.java@e5cf1569d3a4 (annotated)

src/share/classes/com/sun/tools/javac/comp/Attr.java