/*
 * Copyright (c) 2003, 2018, 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.HashSet;
import java.util.Set;
import java.util.function.BiConsumer;

import javax.tools.JavaFileObject;

import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Lint.LintCategory;
import com.sun.tools.javac.code.Scope.ImportFilter;
import com.sun.tools.javac.code.Scope.NamedImportScope;
import com.sun.tools.javac.code.Scope.StarImportScope;
import com.sun.tools.javac.code.Scope.WriteableScope;
import com.sun.tools.javac.code.Source.Feature;
import com.sun.tools.javac.comp.Annotate.AnnotationTypeMetadata;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.DefinedBy.Api;

import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.code.Type.*;
import com.sun.tools.javac.resources.CompilerProperties.Errors;
import com.sun.tools.javac.tree.JCTree.*;

import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Flags.ANNOTATION;
import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
import static com.sun.tools.javac.code.Kinds.Kind.*;
import static com.sun.tools.javac.code.TypeTag.CLASS;
import static com.sun.tools.javac.code.TypeTag.ERROR;
import com.sun.tools.javac.resources.CompilerProperties.Fragments;
import static com.sun.tools.javac.tree.JCTree.Tag.*;

import com.sun.tools.javac.util.Dependencies.CompletionCause;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticFlag;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;

This is the second phase of Enter, in which classes are completed
 by resolving their headers and entering their members in the into
 the class scope. See Enter for an overall overview.
 This class uses internal phases to process the classes. When a phase
 processes classes, the lower phases are not invoked until all classes
 pass through the current phase. Note that it is possible that upper phases
 are run due to recursive completion. The internal phases are:
 - ImportPhase: shallow pass through imports, adds information about imports
                the NamedImportScope and StarImportScope, but avoids queries
                about class hierarchy.
 - HierarchyPhase: resolves the supertypes of the given class. Does not handle
                   type parameters of the class or type argument of the supertypes.
 - HeaderPhase: finishes analysis of the header of the given class by resolving
                type parameters, attributing supertypes including type arguments
                and scheduling full annotation attribution. This phase also adds
                a synthetic default constructor if needed and synthetic "this" field.
 - MembersPhase: resolves headers for fields, methods and constructors in the given class.
                 Also generates synthetic enum members.
 
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.
/** This is the second phase of Enter, in which classes are completed
 *  by resolving their headers and entering their members in the into
 *  the class scope. See Enter for an overall overview.
 *
 *  This class uses internal phases to process the classes. When a phase
 *  processes classes, the lower phases are not invoked until all classes
 *  pass through the current phase. Note that it is possible that upper phases
 *  are run due to recursive completion. The internal phases are:
 *  - ImportPhase: shallow pass through imports, adds information about imports
 *                 the NamedImportScope and StarImportScope, but avoids queries
 *                 about class hierarchy.
 *  - HierarchyPhase: resolves the supertypes of the given class. Does not handle
 *                    type parameters of the class or type argument of the supertypes.
 *  - HeaderPhase: finishes analysis of the header of the given class by resolving
 *                 type parameters, attributing supertypes including type arguments
 *                 and scheduling full annotation attribution. This phase also adds
 *                 a synthetic default constructor if needed and synthetic "this" field.
 *  - MembersPhase: resolves headers for fields, methods and constructors in the given class.
 *                  Also generates synthetic enum members.
 *
 *  <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 TypeEnter implements Completer {
    protected static final Context.Key<TypeEnter> typeEnterKey = new Context.Key<>();

    
A switch to determine whether we check for package/class conflicts
/** A switch to determine whether we check for package/class conflicts
     */
    final static boolean checkClash = true;

    private final Names names;
    private final Enter enter;
    private final MemberEnter memberEnter;
    private final Log log;
    private final Check chk;
    private final Attr attr;
    private final Symtab syms;
    private final TreeMaker make;
    private final Todo todo;
    private final Annotate annotate;
    private final TypeAnnotations typeAnnotations;
    private final Types types;
    private final JCDiagnostic.Factory diags;
    private final DeferredLintHandler deferredLintHandler;
    private final Lint lint;
    private final TypeEnvs typeEnvs;
    private final Dependencies dependencies;

    public static TypeEnter instance(Context context) {
        TypeEnter instance = context.get(typeEnterKey);
        if (instance == null)
            instance = new TypeEnter(context);
        return instance;
    }

    protected TypeEnter(Context context) {
        context.put(typeEnterKey, this);
        names = Names.instance(context);
        enter = Enter.instance(context);
        memberEnter = MemberEnter.instance(context);
        log = Log.instance(context);
        chk = Check.instance(context);
        attr = Attr.instance(context);
        syms = Symtab.instance(context);
        make = TreeMaker.instance(context);
        todo = Todo.instance(context);
        annotate = Annotate.instance(context);
        typeAnnotations = TypeAnnotations.instance(context);
        types = Types.instance(context);
        diags = JCDiagnostic.Factory.instance(context);
        deferredLintHandler = DeferredLintHandler.instance(context);
        lint = Lint.instance(context);
        typeEnvs = TypeEnvs.instance(context);
        dependencies = Dependencies.instance(context);
        Source source = Source.instance(context);
        allowTypeAnnos = Feature.TYPE_ANNOTATIONS.allowedInSource(source);
        allowDeprecationOnImport = Feature.DEPRECATION_ON_IMPORT.allowedInSource(source);
    }

    
Switch: support type annotations.
/** Switch: support type annotations.
     */
    boolean allowTypeAnnos;

    
Switch: should deprecation warnings be issued on import
/**
     * Switch: should deprecation warnings be issued on import
     */
    boolean allowDeprecationOnImport;

    
A flag to disable completion from time to time during member
 enter, as we only need to look up types.  This avoids
 unnecessarily deep recursion.
/** A flag to disable completion from time to time during member
     *  enter, as we only need to look up types.  This avoids
     *  unnecessarily deep recursion.
     */
    boolean completionEnabled = true;

    /* Verify Imports:
     */
    protected void ensureImportsChecked(List<JCCompilationUnit> trees) {
        // if there remain any unimported toplevels (these must have
        // no classes at all), process their import statements as well.
        for (JCCompilationUnit tree : trees) {
            if (!tree.starImportScope.isFilled()) {
                Env<AttrContext> topEnv = enter.topLevelEnv(tree);
                finishImports(tree, () -> { completeClass.resolveImports(tree, topEnv); });
            }
        }
    }

/* ********************************************************************
 * Source completer
 *********************************************************************/

    
Complete entering a class.
 @param sym         The symbol of the class to be completed.
/** Complete entering a class.
     *  @param sym         The symbol of the class to be completed.
     */
    @Override
    public void complete(Symbol sym) throws CompletionFailure {
        // Suppress some (recursive) MemberEnter invocations
        if (!completionEnabled) {
            // Re-install same completer for next time around and return.
            Assert.check((sym.flags() & Flags.COMPOUND) == 0);
            sym.completer = this;
            return;
        }

        try {
            annotate.blockAnnotations();
            sym.flags_field |= UNATTRIBUTED;

            List<Env<AttrContext>> queue;

            dependencies.push((ClassSymbol) sym, CompletionCause.MEMBER_ENTER);
            try {
                queue = completeClass.completeEnvs(List.of(typeEnvs.get((ClassSymbol) sym)));
            } finally {
                dependencies.pop();
            }

            if (!queue.isEmpty()) {
                Set<JCCompilationUnit> seen = new HashSet<>();

                for (Env<AttrContext> env : queue) {
                    if (env.toplevel.defs.contains(env.enclClass) && seen.add(env.toplevel)) {
                        finishImports(env.toplevel, () -> {});
                    }
                }
            }
        } finally {
            annotate.unblockAnnotations();
        }
    }

    void finishImports(JCCompilationUnit toplevel, Runnable resolve) {
        JavaFileObject prev = log.useSource(toplevel.sourcefile);
        try {
            resolve.run();
            chk.checkImportsUnique(toplevel);
            chk.checkImportsResolvable(toplevel);
            chk.checkImportedPackagesObservable(toplevel);
            toplevel.namedImportScope.finalizeScope();
            toplevel.starImportScope.finalizeScope();
        } catch (CompletionFailure cf) {
            chk.completionError(toplevel.pos(), cf);
        } finally {
            log.useSource(prev);
        }
    }

    abstract class Phase {
        private final ListBuffer<Env<AttrContext>> queue = new ListBuffer<>();
        private final Phase next;
        private final CompletionCause phaseName;

        Phase(CompletionCause phaseName, Phase next) {
            this.phaseName = phaseName;
            this.next = next;
        }

        public final List<Env<AttrContext>> completeEnvs(List<Env<AttrContext>> envs) {
            boolean firstToComplete = queue.isEmpty();

            Phase prevTopLevelPhase = topLevelPhase;
            boolean success = false;

            try {
                topLevelPhase = this;
                doCompleteEnvs(envs);
                success = true;
            } finally {
                topLevelPhase = prevTopLevelPhase;
                if (!success && firstToComplete) {
                    //an exception was thrown, e.g. BreakAttr:
                    //the queue would become stale, clear it:
                    queue.clear();
                }
            }

            if (firstToComplete) {
                List<Env<AttrContext>> out = queue.toList();

                queue.clear();
                return next != null ? next.completeEnvs(out) : out;
            } else {
                return List.nil();
            }
        }

        protected void doCompleteEnvs(List<Env<AttrContext>> envs) {
            for (Env<AttrContext> env : envs) {
                JCClassDecl tree = (JCClassDecl)env.tree;

                queue.add(env);

                JavaFileObject prev = log.useSource(env.toplevel.sourcefile);
                DiagnosticPosition prevLintPos = deferredLintHandler.setPos(tree.pos());
                try {
                    dependencies.push(env.enclClass.sym, phaseName);
                    runPhase(env);
                } catch (CompletionFailure ex) {
                    chk.completionError(tree.pos(), ex);
                } finally {
                    dependencies.pop();
                    deferredLintHandler.setPos(prevLintPos);
                    log.useSource(prev);
                }
            }
        }

        protected abstract void runPhase(Env<AttrContext> env);
    }

    private final ImportsPhase completeClass = new ImportsPhase();
    private Phase topLevelPhase;

    
Analyze import clauses.
/**Analyze import clauses.
     */
    private final class ImportsPhase extends Phase {

        public ImportsPhase() {
            super(CompletionCause.IMPORTS_PHASE, new HierarchyPhase());
        }

        Env<AttrContext> env;
        ImportFilter staticImportFilter;
        ImportFilter typeImportFilter;
        BiConsumer<JCImport, CompletionFailure> cfHandler =
                (imp, cf) -> chk.completionError(imp.pos(), cf);

        @Override
        protected void runPhase(Env<AttrContext> env) {
            JCClassDecl tree = env.enclClass;
            ClassSymbol sym = tree.sym;

            // If sym is a toplevel-class, make sure any import
            // clauses in its source file have been seen.
            if (sym.owner.kind == PCK) {
                resolveImports(env.toplevel, env.enclosing(TOPLEVEL));
                todo.append(env);
            }

            if (sym.owner.kind == TYP)
                sym.owner.complete();
        }

        private void resolveImports(JCCompilationUnit tree, Env<AttrContext> env) {
            if (tree.starImportScope.isFilled()) {
                // we must have already processed this toplevel
                return;
            }

            ImportFilter prevStaticImportFilter = staticImportFilter;
            ImportFilter prevTypeImportFilter = typeImportFilter;
            DiagnosticPosition prevLintPos = deferredLintHandler.immediate();
            Lint prevLint = chk.setLint(lint);
            Env<AttrContext> prevEnv = this.env;
            try {
                this.env = env;
                final PackageSymbol packge = env.toplevel.packge;
                this.staticImportFilter =
                        (origin, sym) -> sym.isStatic() &&
                                         chk.importAccessible(sym, packge) &&
                                         sym.isMemberOf((TypeSymbol) origin.owner, types);
                this.typeImportFilter =
                        (origin, sym) -> sym.kind == TYP &&
                                         chk.importAccessible(sym, packge);

                // Import-on-demand java.lang.
                PackageSymbol javaLang = syms.enterPackage(syms.java_base, names.java_lang);
                if (javaLang.members().isEmpty() && !javaLang.exists())
                    throw new FatalError(diags.fragment(Fragments.FatalErrNoJavaLang));
                importAll(make.at(tree.pos()).Import(make.QualIdent(javaLang), false), javaLang, env);

                JCModuleDecl decl = tree.getModuleDecl();

                // Process the package def and all import clauses.
                if (tree.getPackage() != null && decl == null)
                    checkClassPackageClash(tree.getPackage());

                for (JCImport imp : tree.getImports()) {
                    doImport(imp);
                }

                if (decl != null) {
                    //check @Deprecated:
                    markDeprecated(decl.sym, decl.mods.annotations, env);
                    // process module annotations
                    annotate.annotateLater(decl.mods.annotations, env, env.toplevel.modle, null);
                }
            } finally {
                this.env = prevEnv;
                chk.setLint(prevLint);
                deferredLintHandler.setPos(prevLintPos);
                this.staticImportFilter = prevStaticImportFilter;
                this.typeImportFilter = prevTypeImportFilter;
            }
        }

        private void checkClassPackageClash(JCPackageDecl tree) {
            // check that no class exists with same fully qualified name as
            // toplevel package
            if (checkClash && tree.pid != null) {
                Symbol p = env.toplevel.packge;
                while (p.owner != syms.rootPackage) {
                    p.owner.complete(); // enter all class members of p
                    //need to lookup the owning module/package:
                    PackageSymbol pack = syms.lookupPackage(env.toplevel.modle, p.owner.getQualifiedName());
                    if (syms.getClass(pack.modle, p.getQualifiedName()) != null) {
                        log.error(tree.pos,
                                  Errors.PkgClashesWithClassOfSameName(p));
                    }
                    p = p.owner;
                }
            }
            // process package annotations
            annotate.annotateLater(tree.annotations, env, env.toplevel.packge, null);
        }

        private void doImport(JCImport tree) {
            JCFieldAccess imp = (JCFieldAccess)tree.qualid;
            Name name = TreeInfo.name(imp);

            // Create a local environment pointing to this tree to disable
            // effects of other imports in Resolve.findGlobalType
            Env<AttrContext> localEnv = env.dup(tree);

            TypeSymbol p = attr.attribImportQualifier(tree, localEnv).tsym;
            if (name == names.asterisk) {
                // Import on demand.
                chk.checkCanonical(imp.selected);
                if (tree.staticImport)
                    importStaticAll(tree, p, env);
                else
                    importAll(tree, p, env);
            } else {
                // Named type import.
                if (tree.staticImport) {
                    importNamedStatic(tree, p, name, localEnv);
                    chk.checkCanonical(imp.selected);
                } else {
                    Type importedType = attribImportType(imp, localEnv);
                    Type originalType = importedType.getOriginalType();
                    TypeSymbol c = originalType.hasTag(CLASS) ? originalType.tsym : importedType.tsym;
                    chk.checkCanonical(imp);
                    importNamed(tree.pos(), c, env, tree);
                }
            }
        }

        Type attribImportType(JCTree tree, Env<AttrContext> env) {
            Assert.check(completionEnabled);
            Lint prevLint = chk.setLint(allowDeprecationOnImport ?
                    lint : lint.suppress(LintCategory.DEPRECATION, LintCategory.REMOVAL));
            try {
                // To prevent deep recursion, suppress completion of some
                // types.
                completionEnabled = false;
                return attr.attribType(tree, env);
            } finally {
                completionEnabled = true;
                chk.setLint(prevLint);
            }
        }

        
Import all classes of a class or package on demand.
 @param imp           The import that is being handled.
 @param tsym          The class or package the members of which are imported.
 @param env           The env in which the imported classes will be entered.
/** Import all classes of a class or package on demand.
         *  @param imp           The import that is being handled.
         *  @param tsym          The class or package the members of which are imported.
         *  @param env           The env in which the imported classes will be entered.
         */
        private void importAll(JCImport imp,
                               final TypeSymbol tsym,
                               Env<AttrContext> env) {
            env.toplevel.starImportScope.importAll(types, tsym.members(), typeImportFilter, imp, cfHandler);
        }

        
Import all static members of a class or package on demand.
 @param imp           The import that is being handled.
 @param tsym          The class or package the members of which are imported.
 @param env           The env in which the imported classes will be entered.
/** Import all static members of a class or package on demand.
         *  @param imp           The import that is being handled.
         *  @param tsym          The class or package the members of which are imported.
         *  @param env           The env in which the imported classes will be entered.
         */
        private void importStaticAll(JCImport imp,
                                     final TypeSymbol tsym,
                                     Env<AttrContext> env) {
            final StarImportScope toScope = env.toplevel.starImportScope;
            final TypeSymbol origin = tsym;

            toScope.importAll(types, origin.members(), staticImportFilter, imp, cfHandler);
        }

        
Import statics types of a given name.  Non-types are handled in Attr.
 @param imp           The import that is being handled.
 @param tsym          The class from which the name is imported.
 @param name          The (simple) name being imported.
 @param env           The environment containing the named import
                 scope to add to.
/** Import statics types of a given name.  Non-types are handled in Attr.
         *  @param imp           The import that is being handled.
         *  @param tsym          The class from which the name is imported.
         *  @param name          The (simple) name being imported.
         *  @param env           The environment containing the named import
         *                  scope to add to.
         */
        private void importNamedStatic(final JCImport imp,
                                       final TypeSymbol tsym,
                                       final Name name,
                                       final Env<AttrContext> env) {
            if (tsym.kind != TYP) {
                log.error(DiagnosticFlag.RECOVERABLE, imp.pos(), Errors.StaticImpOnlyClassesAndInterfaces);
                return;
            }

            final NamedImportScope toScope = env.toplevel.namedImportScope;
            final Scope originMembers = tsym.members();

            imp.importScope = toScope.importByName(types, originMembers, name, staticImportFilter, imp, cfHandler);
        }

        
Import given class.
 @param pos           Position to be used for error reporting.
 @param tsym          The class to be imported.
 @param env           The environment containing the named import
                 scope to add to.
/** Import given class.
         *  @param pos           Position to be used for error reporting.
         *  @param tsym          The class to be imported.
         *  @param env           The environment containing the named import
         *                  scope to add to.
         */
        private void importNamed(DiagnosticPosition pos, final Symbol tsym, Env<AttrContext> env, JCImport imp) {
            if (tsym.kind == TYP)
                imp.importScope = env.toplevel.namedImportScope.importType(tsym.owner.members(), tsym.owner.members(), tsym);
        }

    }

    
Defines common utility methods used by the HierarchyPhase and HeaderPhase.
/**Defines common utility methods used by the HierarchyPhase and HeaderPhase.
     */
    private abstract class AbstractHeaderPhase extends Phase {

        public AbstractHeaderPhase(CompletionCause phaseName, Phase next) {
            super(phaseName, next);
        }

        protected Env<AttrContext> baseEnv(JCClassDecl tree, Env<AttrContext> env) {
            WriteableScope baseScope = WriteableScope.create(tree.sym);
            //import already entered local classes into base scope
            for (Symbol sym : env.outer.info.scope.getSymbols(NON_RECURSIVE)) {
                if (sym.isLocal()) {
                    baseScope.enter(sym);
                }
            }
            //import current type-parameters into base scope
            if (tree.typarams != null)
                for (List<JCTypeParameter> typarams = tree.typarams;
                     typarams.nonEmpty();
                     typarams = typarams.tail)
                    baseScope.enter(typarams.head.type.tsym);
            Env<AttrContext> outer = env.outer; // the base clause can't see members of this class
            Env<AttrContext> localEnv = outer.dup(tree, outer.info.dup(baseScope));
            localEnv.baseClause = true;
            localEnv.outer = outer;
            localEnv.info.isSelfCall = false;
            return localEnv;
        }

        
Generate a base clause for an enum type.
 @param pos              The position for trees and diagnostics, if any
 @param c                The class symbol of the enum
/** Generate a base clause for an enum type.
         *  @param pos              The position for trees and diagnostics, if any
         *  @param c                The class symbol of the enum
         */
        protected  JCExpression enumBase(int pos, ClassSymbol c) {
            JCExpression result = make.at(pos).
                TypeApply(make.QualIdent(syms.enumSym),
                          List.of(make.Type(c.type)));
            return result;
        }

        protected Type modelMissingTypes(Env<AttrContext> env, Type t, final JCExpression tree, final boolean interfaceExpected) {
            if (!t.hasTag(ERROR))
                return t;

            return new ErrorType(t.getOriginalType(), t.tsym) {
                private Type modelType;

                @Override
                public Type getModelType() {
                    if (modelType == null)
                        modelType = new Synthesizer(env.toplevel.modle, getOriginalType(), interfaceExpected).visit(tree);
                    return modelType;
                }
            };
        }
            // where:
            private class Synthesizer extends JCTree.Visitor {
                ModuleSymbol msym;
                Type originalType;
                boolean interfaceExpected;
                List<ClassSymbol> synthesizedSymbols = List.nil();
                Type result;

                Synthesizer(ModuleSymbol msym, Type originalType, boolean interfaceExpected) {
                    this.msym = msym;
                    this.originalType = originalType;
                    this.interfaceExpected = interfaceExpected;
                }

                Type visit(JCTree tree) {
                    tree.accept(this);
                    return result;
                }

                List<Type> visit(List<? extends JCTree> trees) {
                    ListBuffer<Type> lb = new ListBuffer<>();
                    for (JCTree t: trees)
                        lb.append(visit(t));
                    return lb.toList();
                }

                @Override
                public void visitTree(JCTree tree) {
                    result = syms.errType;
                }

                @Override
                public void visitIdent(JCIdent tree) {
                    if (!tree.type.hasTag(ERROR)) {
                        result = tree.type;
                    } else {
                        result = synthesizeClass(tree.name, msym.unnamedPackage).type;
                    }
                }

                @Override
                public void visitSelect(JCFieldAccess tree) {
                    if (!tree.type.hasTag(ERROR)) {
                        result = tree.type;
                    } else {
                        Type selectedType;
                        boolean prev = interfaceExpected;
                        try {
                            interfaceExpected = false;
                            selectedType = visit(tree.selected);
                        } finally {
                            interfaceExpected = prev;
                        }
                        ClassSymbol c = synthesizeClass(tree.name, selectedType.tsym);
                        result = c.type;
                    }
                }

                @Override
                public void visitTypeApply(JCTypeApply tree) {
                    if (!tree.type.hasTag(ERROR)) {
                        result = tree.type;
                    } else {
                        ClassType clazzType = (ClassType) visit(tree.clazz);
                        if (synthesizedSymbols.contains(clazzType.tsym))
                            synthesizeTyparams((ClassSymbol) clazzType.tsym, tree.arguments.size());
                        final List<Type> actuals = visit(tree.arguments);
                        result = new ErrorType(tree.type, clazzType.tsym) {
                            @Override @DefinedBy(Api.LANGUAGE_MODEL)
                            public List<Type> getTypeArguments() {
                                return actuals;
                            }
                        };
                    }
                }

                ClassSymbol synthesizeClass(Name name, Symbol owner) {
                    int flags = interfaceExpected ? INTERFACE : 0;
                    ClassSymbol c = new ClassSymbol(flags, name, owner);
                    c.members_field = new Scope.ErrorScope(c);
                    c.type = new ErrorType(originalType, c) {
                        @Override @DefinedBy(Api.LANGUAGE_MODEL)
                        public List<Type> getTypeArguments() {
                            return typarams_field;
                        }
                    };
                    synthesizedSymbols = synthesizedSymbols.prepend(c);
                    return c;
                }

                void synthesizeTyparams(ClassSymbol sym, int n) {
                    ClassType ct = (ClassType) sym.type;
                    Assert.check(ct.typarams_field.isEmpty());
                    if (n == 1) {
                        TypeVar v = new TypeVar(names.fromString("T"), sym, syms.botType);
                        ct.typarams_field = ct.typarams_field.prepend(v);
                    } else {
                        for (int i = n; i > 0; i--) {
                            TypeVar v = new TypeVar(names.fromString("T" + i), sym,
                                                    syms.botType);
                            ct.typarams_field = ct.typarams_field.prepend(v);
                        }
                    }
                }
            }

        protected void attribSuperTypes(Env<AttrContext> env, Env<AttrContext> baseEnv) {
            JCClassDecl tree = env.enclClass;
            ClassSymbol sym = tree.sym;
            ClassType ct = (ClassType)sym.type;
            // Determine supertype.
            Type supertype;
            JCExpression extending;

            if (tree.extending != null) {
                extending = clearTypeParams(tree.extending);
                supertype = attr.attribBase(extending, baseEnv, true, false, true);
            } else {
                extending = null;
                supertype = ((tree.mods.flags & Flags.ENUM) != 0)
                ? attr.attribBase(enumBase(tree.pos, sym), baseEnv,
                                  true, false, false)
                : (sym.fullname == names.java_lang_Object)
                ? Type.noType
                : syms.objectType;
            }
            ct.supertype_field = modelMissingTypes(baseEnv, supertype, extending, false);

            // Determine interfaces.
            ListBuffer<Type> interfaces = new ListBuffer<>();
            ListBuffer<Type> all_interfaces = null; // lazy init
            List<JCExpression> interfaceTrees = tree.implementing;
            for (JCExpression iface : interfaceTrees) {
                iface = clearTypeParams(iface);
                Type it = attr.attribBase(iface, baseEnv, false, true, true);
                if (it.hasTag(CLASS)) {
                    interfaces.append(it);
                    if (all_interfaces != null) all_interfaces.append(it);
                } else {
                    if (all_interfaces == null)
                        all_interfaces = new ListBuffer<Type>().appendList(interfaces);
                    all_interfaces.append(modelMissingTypes(baseEnv, it, iface, true));
                }
            }

            if ((sym.flags_field & ANNOTATION) != 0) {
                ct.interfaces_field = List.of(syms.annotationType);
                ct.all_interfaces_field = ct.interfaces_field;
            }  else {
                ct.interfaces_field = interfaces.toList();
                ct.all_interfaces_field = (all_interfaces == null)
                        ? ct.interfaces_field : all_interfaces.toList();
            }
        }
            //where:
            protected JCExpression clearTypeParams(JCExpression superType) {
                return superType;
            }
    }

    private final class HierarchyPhase extends AbstractHeaderPhase implements Completer {

        public HierarchyPhase() {
            super(CompletionCause.HIERARCHY_PHASE, new HeaderPhase());
        }

        @Override
        protected void doCompleteEnvs(List<Env<AttrContext>> envs) {
            //The ClassSymbols in the envs list may not be in the dependency order.
            //To get proper results, for every class or interface C, the supertypes of
            //C must be processed by the HierarchyPhase phase before C.
            //To achieve that, the HierarchyPhase is registered as the Completer for
            //all the classes first, and then all the classes are completed.
            for (Env<AttrContext> env : envs) {
                env.enclClass.sym.completer = this;
            }
            for (Env<AttrContext> env : envs) {
                env.enclClass.sym.complete();
            }
        }

        @Override
        protected void runPhase(Env<AttrContext> env) {
            JCClassDecl tree = env.enclClass;
            ClassSymbol sym = tree.sym;
            ClassType ct = (ClassType)sym.type;

            Env<AttrContext> baseEnv = baseEnv(tree, env);

            attribSuperTypes(env, baseEnv);

            if (sym.fullname == names.java_lang_Object) {
                if (tree.extending != null) {
                    chk.checkNonCyclic(tree.extending.pos(),
                                       ct.supertype_field);
                    ct.supertype_field = Type.noType;
                }
                else if (tree.implementing.nonEmpty()) {
                    chk.checkNonCyclic(tree.implementing.head.pos(),
                                       ct.interfaces_field.head);
                    ct.interfaces_field = List.nil();
                }
            }

            markDeprecated(sym, tree.mods.annotations, baseEnv);

            chk.checkNonCyclicDecl(tree);
        }
            //where:
            @Override
            protected JCExpression clearTypeParams(JCExpression superType) {
                switch (superType.getTag()) {
                    case TYPEAPPLY:
                        return ((JCTypeApply) superType).clazz;
                }

                return superType;
            }

        @Override
        public void complete(Symbol sym) throws CompletionFailure {
            Assert.check((topLevelPhase instanceof ImportsPhase) ||
                         (topLevelPhase == this));

            if (topLevelPhase != this) {
                //only do the processing based on dependencies in the HierarchyPhase:
                sym.completer = this;
                return ;
            }

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

            super.doCompleteEnvs(List.of(env));
        }

    }

    private final class HeaderPhase extends AbstractHeaderPhase {

        public HeaderPhase() {
            super(CompletionCause.HEADER_PHASE, new MembersPhase());
        }

        @Override
        protected void runPhase(Env<AttrContext> env) {
            JCClassDecl tree = env.enclClass;
            ClassSymbol sym = tree.sym;
            ClassType ct = (ClassType)sym.type;

            // create an environment for evaluating the base clauses
            Env<AttrContext> baseEnv = baseEnv(tree, env);

            if (tree.extending != null)
                annotate.queueScanTreeAndTypeAnnotate(tree.extending, baseEnv, sym, tree.pos());
            for (JCExpression impl : tree.implementing)
                annotate.queueScanTreeAndTypeAnnotate(impl, baseEnv, sym, tree.pos());
            annotate.flush();

            attribSuperTypes(env, baseEnv);

            Set<Type> interfaceSet = new HashSet<>();

            for (JCExpression iface : tree.implementing) {
                Type it = iface.type;
                if (it.hasTag(CLASS))
                    chk.checkNotRepeated(iface.pos(), types.erasure(it), interfaceSet);
            }

            annotate.annotateLater(tree.mods.annotations, baseEnv,
                        sym, tree.pos());

            attr.attribTypeVariables(tree.typarams, baseEnv);
            for (JCTypeParameter tp : tree.typarams)
                annotate.queueScanTreeAndTypeAnnotate(tp, baseEnv, sym, tree.pos());

            // check that no package exists with same fully qualified name,
            // but admit classes in the unnamed package which have the same
            // name as a top-level package.
            if (checkClash &&
                sym.owner.kind == PCK && sym.owner != env.toplevel.modle.unnamedPackage &&
                syms.packageExists(env.toplevel.modle, sym.fullname)) {
                log.error(tree.pos, Errors.ClashWithPkgOfSameName(Kinds.kindName(sym),sym));
            }
            if (sym.owner.kind == PCK && (sym.flags_field & PUBLIC) == 0 &&
                !env.toplevel.sourcefile.isNameCompatible(sym.name.toString(),JavaFileObject.Kind.SOURCE)) {
                sym.flags_field |= AUXILIARY;
            }
        }
    }

    
Enter member fields and methods of a class
/** Enter member fields and methods of a class
     */
    private final class MembersPhase extends Phase {

        public MembersPhase() {
            super(CompletionCause.MEMBERS_PHASE, null);
        }

        private boolean completing;
        private List<Env<AttrContext>> todo = List.nil();

        @Override
        protected void doCompleteEnvs(List<Env<AttrContext>> envs) {
            todo = todo.prependList(envs);
            if (completing) {
                return ; //the top-level invocation will handle all envs
            }
            boolean prevCompleting = completing;
            completing = true;
            try {
                while (todo.nonEmpty()) {
                    Env<AttrContext> head = todo.head;
                    todo = todo.tail;
                    super.doCompleteEnvs(List.of(head));
                }
            } finally {
                completing = prevCompleting;
            }
        }

        @Override
        protected void runPhase(Env<AttrContext> env) {
            JCClassDecl tree = env.enclClass;
            ClassSymbol sym = tree.sym;
            ClassType ct = (ClassType)sym.type;

            // Add default constructor if needed.
            if ((sym.flags() & INTERFACE) == 0 &&
                !TreeInfo.hasConstructors(tree.defs)) {
                List<Type> argtypes = List.nil();
                List<Type> typarams = List.nil();
                List<Type> thrown = List.nil();
                long ctorFlags = 0;
                boolean based = false;
                boolean addConstructor = true;
                JCNewClass nc = null;
                if (sym.name.isEmpty()) {
                    nc = (JCNewClass)env.next.tree;
                    if (nc.constructor != null) {
                        addConstructor = nc.constructor.kind != ERR;
                        Type superConstrType = types.memberType(sym.type,
                                                                nc.constructor);
                        argtypes = superConstrType.getParameterTypes();
                        typarams = superConstrType.getTypeArguments();
                        ctorFlags = nc.constructor.flags() & VARARGS;
                        if (nc.encl != null) {
                            argtypes = argtypes.prepend(nc.encl.type);
                            based = true;
                        }
                        thrown = superConstrType.getThrownTypes();
                    }
                }
                if (addConstructor) {
                    MethodSymbol basedConstructor = nc != null ?
                            (MethodSymbol)nc.constructor : null;
                    JCTree constrDef = DefaultConstructor(make.at(tree.pos), sym,
                                                        basedConstructor,
                                                        typarams, argtypes, thrown,
                                                        ctorFlags, based);
                    tree.defs = tree.defs.prepend(constrDef);
                }
            }

            // enter symbols for 'this' into current scope.
            VarSymbol thisSym =
                new VarSymbol(FINAL | HASINIT, names._this, sym.type, sym);
            thisSym.pos = Position.FIRSTPOS;
            env.info.scope.enter(thisSym);
            // if this is a class, enter symbol for 'super' into current scope.
            if ((sym.flags_field & INTERFACE) == 0 &&
                    ct.supertype_field.hasTag(CLASS)) {
                VarSymbol superSym =
                    new VarSymbol(FINAL | HASINIT, names._super,
                                  ct.supertype_field, sym);
                superSym.pos = Position.FIRSTPOS;
                env.info.scope.enter(superSym);
            }

            finishClass(tree, env);

            if (allowTypeAnnos) {
                typeAnnotations.organizeTypeAnnotationsSignatures(env, (JCClassDecl)env.tree);
                typeAnnotations.validateTypeAnnotationsSignatures(env, (JCClassDecl)env.tree);
            }
        }

        
Enter members for a class.
/** Enter members for a class.
         */
        void finishClass(JCClassDecl tree, Env<AttrContext> env) {
            if ((tree.mods.flags & Flags.ENUM) != 0 &&
                !tree.sym.type.hasTag(ERROR) &&
                (types.supertype(tree.sym.type).tsym.flags() & Flags.ENUM) == 0) {
                addEnumMembers(tree, env);
            }
            memberEnter.memberEnter(tree.defs, env);

            if (tree.sym.isAnnotationType()) {
                Assert.check(tree.sym.isCompleted());
                tree.sym.setAnnotationTypeMetadata(new AnnotationTypeMetadata(tree.sym, annotate.annotationTypeSourceCompleter()));
            }
        }

        
Add the implicit members for an enum type
 to the symbol table.
/** Add the implicit members for an enum type
         *  to the symbol table.
         */
        private void addEnumMembers(JCClassDecl tree, Env<AttrContext> env) {
            JCExpression valuesType = make.Type(new ArrayType(tree.sym.type, syms.arrayClass));

            // public static T[] values() { return ???; }
            JCMethodDecl values = make.
                MethodDef(make.Modifiers(Flags.PUBLIC|Flags.STATIC),
                          names.values,
                          valuesType,
                          List.nil(),
                          List.nil(),
                          List.nil(), // thrown
                          null, //make.Block(0, Tree.emptyList.prepend(make.Return(make.Ident(names._null)))),
                          null);
            memberEnter.memberEnter(values, env);

            // public static T valueOf(String name) { return ???; }
            JCMethodDecl valueOf = make.
                MethodDef(make.Modifiers(Flags.PUBLIC|Flags.STATIC),
                          names.valueOf,
                          make.Type(tree.sym.type),
                          List.nil(),
                          List.of(make.VarDef(make.Modifiers(Flags.PARAMETER |
                                                             Flags.MANDATED),
                                                names.fromString("name"),
                                                make.Type(syms.stringType), null)),
                          List.nil(), // thrown
                          null, //make.Block(0, Tree.emptyList.prepend(make.Return(make.Ident(names._null)))),
                          null);
            memberEnter.memberEnter(valueOf, env);
        }

    }

/* ***************************************************************************
 * tree building
 ****************************************************************************/

    
Generate default constructor for given class. For classes different
 from java.lang.Object, this is:
   c(argtype_0 x_0, ..., argtype_n x_n) throws thrown {
     super(x_0, ..., x_n)
   }
 or, if based == true:
   c(argtype_0 x_0, ..., argtype_n x_n) throws thrown {
     x_0.super(x_1, ..., x_n)
   }
 @param make     The tree factory.
 @param c        The class owning the default constructor.
 @param argtypes The parameter types of the constructor.
 @param thrown   The thrown exceptions of the constructor.
 @param based    Is first parameter a this$n?
/** Generate default constructor for given class. For classes different
     *  from java.lang.Object, this is:
     *
     *    c(argtype_0 x_0, ..., argtype_n x_n) throws thrown {
     *      super(x_0, ..., x_n)
     *    }
     *
     *  or, if based == true:
     *
     *    c(argtype_0 x_0, ..., argtype_n x_n) throws thrown {
     *      x_0.super(x_1, ..., x_n)
     *    }
     *
     *  @param make     The tree factory.
     *  @param c        The class owning the default constructor.
     *  @param argtypes The parameter types of the constructor.
     *  @param thrown   The thrown exceptions of the constructor.
     *  @param based    Is first parameter a this$n?
     */
    JCTree DefaultConstructor(TreeMaker make,
                            ClassSymbol c,
                            MethodSymbol baseInit,
                            List<Type> typarams,
                            List<Type> argtypes,
                            List<Type> thrown,
                            long flags,
                            boolean based) {
        JCTree result;
        if ((c.flags() & ENUM) != 0 &&
            (types.supertype(c.type).tsym == syms.enumSym)) {
            // constructors of true enums are private
            flags = (flags & ~AccessFlags) | PRIVATE | GENERATEDCONSTR;
        } else
            flags |= (c.flags() & AccessFlags) | GENERATEDCONSTR;
        if (c.name.isEmpty()) {
            flags |= ANONCONSTR;
        }
        if (based) {
            flags |= ANONCONSTR_BASED;
        }
        Type mType = new MethodType(argtypes, null, thrown, c);
        Type initType = typarams.nonEmpty() ?
            new ForAll(typarams, mType) :
            mType;
        MethodSymbol init = new MethodSymbol(flags, names.init,
                initType, c);
        init.params = createDefaultConstructorParams(make, baseInit, init,
                argtypes, based);
        List<JCVariableDecl> params = make.Params(argtypes, init);
        List<JCStatement> stats = List.nil();
        if (c.type != syms.objectType) {
            stats = stats.prepend(SuperCall(make, typarams, params, based));
        }
        result = make.MethodDef(init, make.Block(0, stats));
        return result;
    }

    private List<VarSymbol> createDefaultConstructorParams(
            TreeMaker make,
            MethodSymbol baseInit,
            MethodSymbol init,
            List<Type> argtypes,
            boolean based) {
        List<VarSymbol> initParams = null;
        List<Type> argTypesList = argtypes;
        if (based) {
            /*  In this case argtypes will have an extra type, compared to baseInit,
             *  corresponding to the type of the enclosing instance i.e.:
             *
             *  Inner i = outer.new Inner(1){}
             *
             *  in the above example argtypes will be (Outer, int) and baseInit
             *  will have parameter's types (int). So in this case we have to add
             *  first the extra type in argtypes and then get the names of the
             *  parameters from baseInit.
             */
            initParams = List.nil();
            VarSymbol param = new VarSymbol(PARAMETER, make.paramName(0), argtypes.head, init);
            initParams = initParams.append(param);
            argTypesList = argTypesList.tail;
        }
        if (baseInit != null && baseInit.params != null &&
            baseInit.params.nonEmpty() && argTypesList.nonEmpty()) {
            initParams = (initParams == null) ? List.nil() : initParams;
            List<VarSymbol> baseInitParams = baseInit.params;
            while (baseInitParams.nonEmpty() && argTypesList.nonEmpty()) {
                VarSymbol param = new VarSymbol(baseInitParams.head.flags() | PARAMETER,
                        baseInitParams.head.name, argTypesList.head, init);
                initParams = initParams.append(param);
                baseInitParams = baseInitParams.tail;
                argTypesList = argTypesList.tail;
            }
        }
        return initParams;
    }

    
Generate call to superclass constructor. This is:
   super(id_0, ..., id_n)
or, if based == true
   id_0.super(id_1,...,id_n)
 where id_0, ..., id_n are the names of the given parameters.
 @param make    The tree factory
 @param params  The parameters that need to be passed to super
 @param typarams  The type parameters that need to be passed to super
 @param based   Is first parameter a this$n?
/** Generate call to superclass constructor. This is:
     *
     *    super(id_0, ..., id_n)
     *
     * or, if based == true
     *
     *    id_0.super(id_1,...,id_n)
     *
     *  where id_0, ..., id_n are the names of the given parameters.
     *
     *  @param make    The tree factory
     *  @param params  The parameters that need to be passed to super
     *  @param typarams  The type parameters that need to be passed to super
     *  @param based   Is first parameter a this$n?
     */
    JCExpressionStatement SuperCall(TreeMaker make,
                   List<Type> typarams,
                   List<JCVariableDecl> params,
                   boolean based) {
        JCExpression meth;
        if (based) {
            meth = make.Select(make.Ident(params.head), names._super);
            params = params.tail;
        } else {
            meth = make.Ident(names._super);
        }
        List<JCExpression> typeargs = typarams.nonEmpty() ? make.Types(typarams) : null;
        return make.Exec(make.Apply(typeargs, meth, make.Idents(params)));
    }

    
Mark sym deprecated if annotations contain @Deprecated annotation.
/**
     * Mark sym deprecated if annotations contain @Deprecated annotation.
     */
    public void markDeprecated(Symbol sym, List<JCAnnotation> annotations, Env<AttrContext> env) {
        // In general, we cannot fully process annotations yet,  but we
        // can attribute the annotation types and then check to see if the
        // @Deprecated annotation is present.
        attr.attribAnnotationTypes(annotations, env);
        handleDeprecatedAnnotations(annotations, sym);
    }

    
If a list of annotations contains a reference to java.lang.Deprecated,
set the DEPRECATED flag.
If the annotation is marked forRemoval=true, also set DEPRECATED_REMOVAL.
/**
     * If a list of annotations contains a reference to java.lang.Deprecated,
     * set the DEPRECATED flag.
     * If the annotation is marked forRemoval=true, also set DEPRECATED_REMOVAL.
     **/
    private void handleDeprecatedAnnotations(List<JCAnnotation> annotations, Symbol sym) {
        for (List<JCAnnotation> al = annotations; !al.isEmpty(); al = al.tail) {
            JCAnnotation a = al.head;
            if (a.annotationType.type == syms.deprecatedType) {
                sym.flags_field |= (Flags.DEPRECATED | Flags.DEPRECATED_ANNOTATION);
                a.args.stream()
                        .filter(e -> e.hasTag(ASSIGN))
                        .map(e -> (JCAssign) e)
                        .filter(assign -> TreeInfo.name(assign.lhs) == names.forRemoval)
                        .findFirst()
                        .ifPresent(assign -> {
                            JCExpression rhs = TreeInfo.skipParens(assign.rhs);
                            if (rhs.hasTag(LITERAL)
                                    && Boolean.TRUE.equals(((JCLiteral) rhs).getValue())) {
                                sym.flags_field |= DEPRECATED_REMOVAL;
                            }
                        });
            }
        }
    }
}