mcimadamore@1347: /*
mcimadamore@1347:  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
mcimadamore@1347:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
mcimadamore@1347:  *
mcimadamore@1347:  * This code is free software; you can redistribute it and/or modify it
mcimadamore@1347:  * under the terms of the GNU General Public License version 2 only, as
mcimadamore@1347:  * published by the Free Software Foundation.  Oracle designates this
mcimadamore@1347:  * particular file as subject to the "Classpath" exception as provided
mcimadamore@1347:  * by Oracle in the LICENSE file that accompanied this code.
mcimadamore@1347:  *
mcimadamore@1347:  * This code is distributed in the hope that it will be useful, but WITHOUT
mcimadamore@1347:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
mcimadamore@1347:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
mcimadamore@1347:  * version 2 for more details (a copy is included in the LICENSE file that
mcimadamore@1347:  * accompanied this code).
mcimadamore@1347:  *
mcimadamore@1347:  * You should have received a copy of the GNU General Public License version
mcimadamore@1347:  * 2 along with this work; if not, write to the Free Software Foundation,
mcimadamore@1347:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
mcimadamore@1347:  *
mcimadamore@1347:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
mcimadamore@1347:  * or visit www.oracle.com if you need additional information or have any
mcimadamore@1347:  * questions.
mcimadamore@1347:  */
mcimadamore@1347: 
mcimadamore@1347: package com.sun.tools.javac.comp;
mcimadamore@1347: 
mcimadamore@1347: import com.sun.tools.javac.code.*;
mcimadamore@1347: import com.sun.tools.javac.tree.*;
mcimadamore@1347: import com.sun.tools.javac.util.*;
mcimadamore@1347: import com.sun.tools.javac.code.Symbol.*;
mcimadamore@1347: import com.sun.tools.javac.code.Type.*;
mcimadamore@1347: import com.sun.tools.javac.comp.Attr.ResultInfo;
mcimadamore@1347: import com.sun.tools.javac.comp.Infer.InferenceContext;
mcimadamore@1347: import com.sun.tools.javac.comp.Resolve.MethodResolutionPhase;
mcimadamore@1347: import com.sun.tools.javac.tree.JCTree.*;
mcimadamore@1347: 
mcimadamore@1347: import javax.tools.JavaFileObject;
mcimadamore@1347: 
mcimadamore@1347: import java.util.ArrayList;
mcimadamore@1347: import java.util.HashSet;
mcimadamore@1347: import java.util.Map;
mcimadamore@1347: import java.util.Queue;
mcimadamore@1347: import java.util.Set;
mcimadamore@1347: import java.util.WeakHashMap;
mcimadamore@1347: 
mcimadamore@1347: import static com.sun.tools.javac.code.TypeTags.*;
mcimadamore@1347: import static com.sun.tools.javac.tree.JCTree.Tag.*;
mcimadamore@1347: import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
mcimadamore@1347: 
mcimadamore@1347: /**
mcimadamore@1347:  * This is an helper class that is used to perform deferred type-analysis.
mcimadamore@1347:  * Each time a poly expression occurs in argument position, javac attributes it
mcimadamore@1347:  * with a temporary 'deferred type' that is checked (possibly multiple times)
mcimadamore@1347:  * against an expected formal type.
mcimadamore@1347:  *
mcimadamore@1347:  *  <p><b>This is NOT part of any supported API.
mcimadamore@1347:  *  If you write code that depends on this, you do so at your own risk.
mcimadamore@1347:  *  This code and its internal interfaces are subject to change or
mcimadamore@1347:  *  deletion without notice.</b>
mcimadamore@1347:  */
mcimadamore@1347: public class DeferredAttr extends JCTree.Visitor {
mcimadamore@1347:     protected static final Context.Key<DeferredAttr> deferredAttrKey =
mcimadamore@1347:         new Context.Key<DeferredAttr>();
mcimadamore@1347: 
mcimadamore@1347:     final Attr attr;
mcimadamore@1347:     final Check chk;
mcimadamore@1347:     final Enter enter;
mcimadamore@1347:     final Infer infer;
mcimadamore@1347:     final Log log;
mcimadamore@1347:     final Symtab syms;
mcimadamore@1347:     final TreeMaker make;
mcimadamore@1347:     final Types types;
mcimadamore@1347: 
mcimadamore@1347:     public static DeferredAttr instance(Context context) {
mcimadamore@1347:         DeferredAttr instance = context.get(deferredAttrKey);
mcimadamore@1347:         if (instance == null)
mcimadamore@1347:             instance = new DeferredAttr(context);
mcimadamore@1347:         return instance;
mcimadamore@1347:     }
mcimadamore@1347: 
mcimadamore@1347:     protected DeferredAttr(Context context) {
mcimadamore@1347:         context.put(deferredAttrKey, this);
mcimadamore@1347:         attr = Attr.instance(context);
mcimadamore@1347:         chk = Check.instance(context);
mcimadamore@1347:         enter = Enter.instance(context);
mcimadamore@1347:         infer = Infer.instance(context);
mcimadamore@1347:         log = Log.instance(context);
mcimadamore@1347:         syms = Symtab.instance(context);
mcimadamore@1347:         make = TreeMaker.instance(context);
mcimadamore@1347:         types = Types.instance(context);
mcimadamore@1347:     }
mcimadamore@1347: 
mcimadamore@1347:     /**
mcimadamore@1347:      * This type represents a deferred type. A deferred type starts off with
mcimadamore@1347:      * no information on the underlying expression type. Such info needs to be
mcimadamore@1347:      * discovered through type-checking the deferred type against a target-type.
mcimadamore@1347:      * Every deferred type keeps a pointer to the AST node from which it originated.
mcimadamore@1347:      */
mcimadamore@1347:     public class DeferredType extends Type {
mcimadamore@1347: 
mcimadamore@1347:         public JCExpression tree;
mcimadamore@1347:         Env<AttrContext> env;
mcimadamore@1347:         AttrMode mode;
mcimadamore@1347:         SpeculativeCache speculativeCache;
mcimadamore@1347: 
mcimadamore@1347:         DeferredType(JCExpression tree, Env<AttrContext> env) {
mcimadamore@1347:             super(DEFERRED, null);
mcimadamore@1347:             this.tree = tree;
mcimadamore@1347:             this.env = env.dup(tree, env.info.dup());
mcimadamore@1347:             this.speculativeCache = new SpeculativeCache();
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         /**
mcimadamore@1347:          * A speculative cache is used to keep track of all overload resolution rounds
mcimadamore@1347:          * that triggered speculative attribution on a given deferred type. Each entry
mcimadamore@1347:          * stores a pointer to the speculative tree and the resolution phase in which the entry
mcimadamore@1347:          * has been added.
mcimadamore@1347:          */
mcimadamore@1347:         class SpeculativeCache {
mcimadamore@1347: 
mcimadamore@1347:             private Map<Symbol, List<Entry>> cache =
mcimadamore@1347:                     new WeakHashMap<Symbol, List<Entry>>();
mcimadamore@1347: 
mcimadamore@1347:             class Entry {
mcimadamore@1347:                 JCTree speculativeTree;
mcimadamore@1347:                 Resolve.MethodResolutionPhase phase;
mcimadamore@1347: 
mcimadamore@1347:                 public Entry(JCTree speculativeTree, MethodResolutionPhase phase) {
mcimadamore@1347:                     this.speculativeTree = speculativeTree;
mcimadamore@1347:                     this.phase = phase;
mcimadamore@1347:                 }
mcimadamore@1347: 
mcimadamore@1347:                 boolean matches(Resolve.MethodResolutionPhase phase) {
mcimadamore@1347:                     return this.phase == phase;
mcimadamore@1347:                 }
mcimadamore@1347:             }
mcimadamore@1347: 
mcimadamore@1347:             /**
mcimadamore@1347:              * Clone a speculative cache entry as a fresh entry associated
mcimadamore@1347:              * with a new method (this maybe required to fixup speculative cache
mcimadamore@1347:              * misses after Resolve.access())
mcimadamore@1347:              */
mcimadamore@1347:             void dupAllTo(Symbol from, Symbol to) {
mcimadamore@1347:                 Assert.check(cache.get(to) == null);
mcimadamore@1347:                 List<Entry> entries = cache.get(from);
mcimadamore@1347:                 if (entries != null) {
mcimadamore@1347:                     cache.put(to, entries);
mcimadamore@1347:                 }
mcimadamore@1347:             }
mcimadamore@1347: 
mcimadamore@1347:             /**
mcimadamore@1347:              * Retrieve a speculative cache entry corresponding to given symbol
mcimadamore@1347:              * and resolution phase
mcimadamore@1347:              */
mcimadamore@1347:             Entry get(Symbol msym, MethodResolutionPhase phase) {
mcimadamore@1347:                 List<Entry> entries = cache.get(msym);
mcimadamore@1347:                 if (entries == null) return null;
mcimadamore@1347:                 for (Entry e : entries) {
mcimadamore@1347:                     if (e.matches(phase)) return e;
mcimadamore@1347:                 }
mcimadamore@1347:                 return null;
mcimadamore@1347:             }
mcimadamore@1347: 
mcimadamore@1347:             /**
mcimadamore@1347:              * Stores a speculative cache entry corresponding to given symbol
mcimadamore@1347:              * and resolution phase
mcimadamore@1347:              */
mcimadamore@1347:             void put(Symbol msym, JCTree speculativeTree, MethodResolutionPhase phase) {
mcimadamore@1347:                 List<Entry> entries = cache.get(msym);
mcimadamore@1347:                 if (entries == null) {
mcimadamore@1347:                     entries = List.nil();
mcimadamore@1347:                 }
mcimadamore@1347:                 cache.put(msym, entries.prepend(new Entry(speculativeTree, phase)));
mcimadamore@1347:             }
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         /**
mcimadamore@1347:          * Get the type that has been computed during a speculative attribution round
mcimadamore@1347:          */
mcimadamore@1347:         Type speculativeType(Symbol msym, MethodResolutionPhase phase) {
mcimadamore@1347:             SpeculativeCache.Entry e = speculativeCache.get(msym, phase);
mcimadamore@1347:             return e != null ? e.speculativeTree.type : Type.noType;
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         /**
mcimadamore@1347:          * Check a deferred type against a potential target-type. Depending on
mcimadamore@1347:          * the current attribution mode, a normal vs. speculative attribution
mcimadamore@1347:          * round is performed on the underlying AST node. There can be only one
mcimadamore@1347:          * speculative round for a given target method symbol; moreover, a normal
mcimadamore@1347:          * attribution round must follow one or more speculative rounds.
mcimadamore@1347:          */
mcimadamore@1347:         Type check(ResultInfo resultInfo) {
mcimadamore@1347:             DeferredAttrContext deferredAttrContext =
mcimadamore@1347:                     resultInfo.checkContext.deferredAttrContext();
mcimadamore@1347:             Assert.check(deferredAttrContext != emptyDeferredAttrContext);
mcimadamore@1347:             List<Type> stuckVars = stuckVars(tree, resultInfo);
mcimadamore@1347:             if (stuckVars.nonEmpty()) {
mcimadamore@1347:                 deferredAttrContext.addDeferredAttrNode(this, resultInfo, stuckVars);
mcimadamore@1347:                 return Type.noType;
mcimadamore@1347:             } else {
mcimadamore@1347:                 try {
mcimadamore@1347:                     switch (deferredAttrContext.mode) {
mcimadamore@1347:                         case SPECULATIVE:
mcimadamore@1347:                             Assert.check(mode == null ||
mcimadamore@1347:                                     (mode == AttrMode.SPECULATIVE &&
mcimadamore@1347:                                     speculativeType(deferredAttrContext.msym, deferredAttrContext.phase).tag == NONE));
mcimadamore@1347:                             JCTree speculativeTree = attribSpeculative(tree, env, resultInfo);
mcimadamore@1347:                             speculativeCache.put(deferredAttrContext.msym, speculativeTree, deferredAttrContext.phase);
mcimadamore@1347:                             return speculativeTree.type;
mcimadamore@1347:                         case CHECK:
mcimadamore@1347:                             Assert.check(mode == AttrMode.SPECULATIVE);
mcimadamore@1347:                             return attr.attribTree(tree, env, resultInfo);
mcimadamore@1347:                     }
mcimadamore@1347:                     Assert.error();
mcimadamore@1347:                     return null;
mcimadamore@1347:                 } finally {
mcimadamore@1347:                     mode = deferredAttrContext.mode;
mcimadamore@1347:                 }
mcimadamore@1347:             }
mcimadamore@1347:         }
mcimadamore@1347:     }
mcimadamore@1347: 
mcimadamore@1347:     /**
mcimadamore@1347:      * The 'mode' in which the deferred type is to be type-checked
mcimadamore@1347:      */
mcimadamore@1347:     public enum AttrMode {
mcimadamore@1347:         /**
mcimadamore@1347:          * A speculative type-checking round is used during overload resolution
mcimadamore@1347:          * mainly to generate constraints on inference variables. Side-effects
mcimadamore@1347:          * arising from type-checking the expression associated with the deferred
mcimadamore@1347:          * type are reversed after the speculative round finishes. This means the
mcimadamore@1347:          * expression tree will be left in a blank state.
mcimadamore@1347:          */
mcimadamore@1347:         SPECULATIVE,
mcimadamore@1347:         /**
mcimadamore@1347:          * This is the plain type-checking mode. Produces side-effects on the underlying AST node
mcimadamore@1347:          */
mcimadamore@1347:         CHECK;
mcimadamore@1347:     }
mcimadamore@1347: 
mcimadamore@1347:     /**
mcimadamore@1347:      * Routine that performs speculative type-checking; the input AST node is
mcimadamore@1347:      * cloned (to avoid side-effects cause by Attr) and compiler state is
mcimadamore@1347:      * restored after type-checking. All diagnostics (but critical ones) are
mcimadamore@1347:      * disabled during speculative type-checking.
mcimadamore@1347:      */
mcimadamore@1347:     JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo) {
mcimadamore@1347:         JCTree newTree = new TreeCopier<Object>(make).copy(tree);
mcimadamore@1347:         Env<AttrContext> speculativeEnv = env.dup(newTree, env.info.dup(env.info.scope.dupUnshared()));
mcimadamore@1347:         speculativeEnv.info.scope.owner = env.info.scope.owner;
mcimadamore@1347:         Filter<JCDiagnostic> prevDeferDiagsFilter = log.deferredDiagFilter;
mcimadamore@1347:         Queue<JCDiagnostic> prevDeferredDiags = log.deferredDiagnostics;
mcimadamore@1347:         final JavaFileObject currentSource = log.currentSourceFile();
mcimadamore@1347:         try {
mcimadamore@1347:             log.deferredDiagnostics = new ListBuffer<JCDiagnostic>();
mcimadamore@1347:             log.deferredDiagFilter = new Filter<JCDiagnostic>() {
mcimadamore@1347:                 public boolean accepts(JCDiagnostic t) {
mcimadamore@1347:                     return t.getDiagnosticSource().getFile().equals(currentSource);
mcimadamore@1347:                 }
mcimadamore@1347:             };
mcimadamore@1347:             attr.attribTree(newTree, speculativeEnv, resultInfo);
mcimadamore@1347:             unenterScanner.scan(newTree);
mcimadamore@1347:             return newTree;
mcimadamore@1347:         } catch (Abort ex) {
mcimadamore@1347:             //if some very bad condition occurred during deferred attribution
mcimadamore@1347:             //we should dump all errors before killing javac
mcimadamore@1347:             log.reportDeferredDiagnostics();
mcimadamore@1347:             throw ex;
mcimadamore@1347:         } finally {
mcimadamore@1347:             unenterScanner.scan(newTree);
mcimadamore@1347:             log.deferredDiagFilter = prevDeferDiagsFilter;
mcimadamore@1347:             log.deferredDiagnostics = prevDeferredDiags;
mcimadamore@1347:         }
mcimadamore@1347:     }
mcimadamore@1347:     //where
mcimadamore@1347:         protected TreeScanner unenterScanner = new TreeScanner() {
mcimadamore@1347:             @Override
mcimadamore@1347:             public void visitClassDef(JCClassDecl tree) {
mcimadamore@1347:                 ClassSymbol csym = tree.sym;
mcimadamore@1347:                 enter.typeEnvs.remove(csym);
mcimadamore@1347:                 chk.compiled.remove(csym.flatname);
mcimadamore@1347:                 syms.classes.remove(csym.flatname);
mcimadamore@1347:                 super.visitClassDef(tree);
mcimadamore@1347:             }
mcimadamore@1347:         };
mcimadamore@1347: 
mcimadamore@1347:     /**
mcimadamore@1347:      * A deferred context is created on each method check. A deferred context is
mcimadamore@1347:      * used to keep track of information associated with the method check, such as
mcimadamore@1347:      * the symbol of the method being checked, the overload resolution phase,
mcimadamore@1347:      * the kind of attribution mode to be applied to deferred types and so forth.
mcimadamore@1347:      * As deferred types are processed (by the method check routine) stuck AST nodes
mcimadamore@1347:      * are added (as new deferred attribution nodes) to this context. The complete()
mcimadamore@1347:      * routine makes sure that all pending nodes are properly processed, by
mcimadamore@1347:      * progressively instantiating all inference variables on which one or more
mcimadamore@1347:      * deferred attribution node is stuck.
mcimadamore@1347:      */
mcimadamore@1347:     class DeferredAttrContext {
mcimadamore@1347: 
mcimadamore@1347:         /** attribution mode */
mcimadamore@1347:         final AttrMode mode;
mcimadamore@1347: 
mcimadamore@1347:         /** symbol of the method being checked */
mcimadamore@1347:         final Symbol msym;
mcimadamore@1347: 
mcimadamore@1347:         /** method resolution step */
mcimadamore@1347:         final Resolve.MethodResolutionPhase phase;
mcimadamore@1347: 
mcimadamore@1347:         /** inference context */
mcimadamore@1347:         final InferenceContext inferenceContext;
mcimadamore@1347: 
mcimadamore@1347:         /** list of deferred attribution nodes to be processed */
mcimadamore@1347:         ArrayList<DeferredAttrNode> deferredAttrNodes = new ArrayList<DeferredAttrNode>();
mcimadamore@1347: 
mcimadamore@1347:         DeferredAttrContext(AttrMode mode, Symbol msym, MethodResolutionPhase phase, InferenceContext inferenceContext) {
mcimadamore@1347:             this.mode = mode;
mcimadamore@1347:             this.msym = msym;
mcimadamore@1347:             this.phase = phase;
mcimadamore@1347:             this.inferenceContext = inferenceContext;
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         /**
mcimadamore@1347:          * Adds a node to the list of deferred attribution nodes - used by Resolve.rawCheckArgumentsApplicable
mcimadamore@1347:          * Nodes added this way act as 'roots' for the out-of-order method checking process.
mcimadamore@1347:          */
mcimadamore@1347:         void addDeferredAttrNode(final DeferredType dt, ResultInfo resultInfo, List<Type> stuckVars) {
mcimadamore@1347:             deferredAttrNodes.add(new DeferredAttrNode(dt, resultInfo, stuckVars));
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         /**
mcimadamore@1347:          * Incrementally process all nodes, by skipping 'stuck' nodes and attributing
mcimadamore@1347:          * 'unstuck' ones. If at any point no progress can be made (no 'unstuck' nodes)
mcimadamore@1347:          * some inference variable might get eagerly instantiated so that all nodes
mcimadamore@1347:          * can be type-checked.
mcimadamore@1347:          */
mcimadamore@1347:         void complete() {
mcimadamore@1347:             while (!deferredAttrNodes.isEmpty()) {
mcimadamore@1347:                 Set<Type> stuckVars = new HashSet<Type>();
mcimadamore@1347:                 boolean progress = false;
mcimadamore@1347:                 //scan a defensive copy of the node list - this is because a deferred
mcimadamore@1347:                 //attribution round can add new nodes to the list
mcimadamore@1347:                 for (DeferredAttrNode deferredAttrNode : List.from(deferredAttrNodes)) {
mcimadamore@1347:                     if (!deferredAttrNode.isStuck()) {
mcimadamore@1347:                         deferredAttrNode.process();
mcimadamore@1347:                         deferredAttrNodes.remove(deferredAttrNode);
mcimadamore@1347:                         progress = true;
mcimadamore@1347:                     } else {
mcimadamore@1347:                         stuckVars.addAll(deferredAttrNode.stuckVars);
mcimadamore@1347:                     }
mcimadamore@1347:                 }
mcimadamore@1347:                 if (!progress) {
mcimadamore@1347:                     //remove all variables that have already been instantiated
mcimadamore@1347:                     //from the list of stuck variables
mcimadamore@1347:                     inferenceContext.solveAny(inferenceContext.freeVarsIn(List.from(stuckVars)), types, infer);
mcimadamore@1347:                     inferenceContext.notifyChange(types);
mcimadamore@1347:                 }
mcimadamore@1347:             }
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         /**
mcimadamore@1347:          * Class representing a deferred attribution node. It keeps track of
mcimadamore@1347:          * a deferred type, along with the expected target type information.
mcimadamore@1347:          */
mcimadamore@1347:         class DeferredAttrNode implements Infer.InferenceContext.FreeTypeListener {
mcimadamore@1347: 
mcimadamore@1347:             /** underlying deferred type */
mcimadamore@1347:             DeferredType dt;
mcimadamore@1347: 
mcimadamore@1347:             /** underlying target type information */
mcimadamore@1347:             ResultInfo resultInfo;
mcimadamore@1347: 
mcimadamore@1347:             /** list of uninferred inference variables causing this node to be stuck */
mcimadamore@1347:             List<Type> stuckVars;
mcimadamore@1347: 
mcimadamore@1347:             DeferredAttrNode(DeferredType dt, ResultInfo resultInfo, List<Type> stuckVars) {
mcimadamore@1347:                 this.dt = dt;
mcimadamore@1347:                 this.resultInfo = resultInfo;
mcimadamore@1347:                 this.stuckVars = stuckVars;
mcimadamore@1347:                 if (!stuckVars.isEmpty()) {
mcimadamore@1347:                     resultInfo.checkContext.inferenceContext().addFreeTypeListener(stuckVars, this);
mcimadamore@1347:                 }
mcimadamore@1347:             }
mcimadamore@1347: 
mcimadamore@1347:             @Override
mcimadamore@1347:             public void typesInferred(InferenceContext inferenceContext) {
mcimadamore@1347:                 stuckVars = List.nil();
mcimadamore@1347:                 resultInfo = resultInfo.dup(inferenceContext.asInstType(resultInfo.pt, types));
mcimadamore@1347:             }
mcimadamore@1347: 
mcimadamore@1347:             /**
mcimadamore@1347:              * is this node stuck?
mcimadamore@1347:              */
mcimadamore@1347:             boolean isStuck() {
mcimadamore@1347:                 return stuckVars.nonEmpty();
mcimadamore@1347:             }
mcimadamore@1347: 
mcimadamore@1347:             /**
mcimadamore@1347:              * Process a deferred attribution node.
mcimadamore@1347:              * Invariant: a stuck node cannot be processed.
mcimadamore@1347:              */
mcimadamore@1347:             void process() {
mcimadamore@1347:                 if (isStuck()) {
mcimadamore@1347:                     throw new IllegalStateException("Cannot process a stuck deferred node");
mcimadamore@1347:                 }
mcimadamore@1347:                 dt.check(resultInfo);
mcimadamore@1347:             }
mcimadamore@1347:         }
mcimadamore@1347:     }
mcimadamore@1347: 
mcimadamore@1347:     /** an empty deferred attribution context - all methods throw exceptions */
mcimadamore@1347:     final DeferredAttrContext emptyDeferredAttrContext =
mcimadamore@1347:             new DeferredAttrContext(null, null, null, null) {
mcimadamore@1347:                 @Override
mcimadamore@1347:                 void addDeferredAttrNode(DeferredType dt, ResultInfo ri, List<Type> stuckVars) {
mcimadamore@1347:                     Assert.error("Empty deferred context!");
mcimadamore@1347:                 }
mcimadamore@1347:                 @Override
mcimadamore@1347:                 void complete() {
mcimadamore@1347:                     Assert.error("Empty deferred context!");
mcimadamore@1347:                 }
mcimadamore@1347:             };
mcimadamore@1347: 
mcimadamore@1347:     /**
mcimadamore@1347:      * Map a list of types possibly containing one or more deferred types
mcimadamore@1347:      * into a list of ordinary types. Each deferred type D is mapped into a type T,
mcimadamore@1347:      * where T is computed by retrieving the type that has already been
mcimadamore@1347:      * computed for D during a previous deferred attribution round of the given kind.
mcimadamore@1347:      */
mcimadamore@1347:     class DeferredTypeMap extends Type.Mapping {
mcimadamore@1347: 
mcimadamore@1347:         DeferredAttrContext deferredAttrContext;
mcimadamore@1347: 
mcimadamore@1347:         protected DeferredTypeMap(AttrMode mode, Symbol msym, MethodResolutionPhase phase) {
mcimadamore@1347:             super(String.format("deferredTypeMap[%s]", mode));
mcimadamore@1347:             this.deferredAttrContext = new DeferredAttrContext(mode, msym, phase, infer.emptyContext);
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         protected boolean validState(DeferredType dt) {
mcimadamore@1347:             return dt.mode != null &&
mcimadamore@1347:                     deferredAttrContext.mode.ordinal() <= dt.mode.ordinal();
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         @Override
mcimadamore@1347:         public Type apply(Type t) {
mcimadamore@1347:             if (t.tag != DEFERRED) {
mcimadamore@1347:                 return t.map(this);
mcimadamore@1347:             } else {
mcimadamore@1347:                 DeferredType dt = (DeferredType)t;
mcimadamore@1347:                 Assert.check(validState(dt));
mcimadamore@1347:                 return typeOf(dt);
mcimadamore@1347:             }
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         protected Type typeOf(DeferredType dt) {
mcimadamore@1347:             switch (deferredAttrContext.mode) {
mcimadamore@1347:                 case CHECK:
mcimadamore@1347:                     return dt.tree.type == null ? Type.noType : dt.tree.type;
mcimadamore@1347:                 case SPECULATIVE:
mcimadamore@1347:                     return dt.speculativeType(deferredAttrContext.msym, deferredAttrContext.phase);
mcimadamore@1347:             }
mcimadamore@1347:             Assert.error();
mcimadamore@1347:             return null;
mcimadamore@1347:         }
mcimadamore@1347:     }
mcimadamore@1347: 
mcimadamore@1347:     /**
mcimadamore@1347:      * Specialized recovery deferred mapping.
mcimadamore@1347:      * Each deferred type D is mapped into a type T, where T is computed either by
mcimadamore@1347:      * (i) retrieving the type that has already been computed for D during a previous
mcimadamore@1347:      * attribution round (as before), or (ii) by synthesizing a new type R for D
mcimadamore@1347:      * (the latter step is useful in a recovery scenario).
mcimadamore@1347:      */
mcimadamore@1347:     public class RecoveryDeferredTypeMap extends DeferredTypeMap {
mcimadamore@1347: 
mcimadamore@1347:         public RecoveryDeferredTypeMap(AttrMode mode, Symbol msym, MethodResolutionPhase phase) {
mcimadamore@1347:             super(mode, msym, phase);
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         @Override
mcimadamore@1347:         protected Type typeOf(DeferredType dt) {
mcimadamore@1347:             Type owntype = super.typeOf(dt);
mcimadamore@1347:             return owntype.tag == NONE ?
mcimadamore@1347:                         recover(dt) : owntype;
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         @Override
mcimadamore@1347:         protected boolean validState(DeferredType dt) {
mcimadamore@1347:             return true;
mcimadamore@1347:         }
mcimadamore@1347: 
mcimadamore@1347:         /**
mcimadamore@1347:          * Synthesize a type for a deferred type that hasn't been previously
mcimadamore@1347:          * reduced to an ordinary type. Functional deferred types and conditionals
mcimadamore@1347:          * are mapped to themselves, in order to have a richer diagnostic
mcimadamore@1347:          * representation. Remaining deferred types are attributed using
mcimadamore@1347:          * a default expected type (j.l.Object).
mcimadamore@1347:          */
mcimadamore@1347:         private Type recover(DeferredType dt) {
mcimadamore@1348:             dt.check(attr.new RecoveryInfo(deferredAttrContext));
mcimadamore@1347:             switch (TreeInfo.skipParens(dt.tree).getTag()) {
mcimadamore@1347:                 case LAMBDA:
mcimadamore@1347:                 case REFERENCE:
mcimadamore@1347:                 case CONDEXPR:
mcimadamore@1347:                     //propagate those deferred types to the
mcimadamore@1347:                     //diagnostic formatter
mcimadamore@1347:                     return dt;
mcimadamore@1347:                 default:
mcimadamore@1347:                     return super.apply(dt);
mcimadamore@1347:             }
mcimadamore@1347:         }
mcimadamore@1347:     }
mcimadamore@1347: 
mcimadamore@1347:     /**
mcimadamore@1347:      * Retrieves the list of inference variables that need to be inferred before
mcimadamore@1347:      * an AST node can be type-checked
mcimadamore@1347:      */
mcimadamore@1347:     @SuppressWarnings("fallthrough")
mcimadamore@1348:     List<Type> stuckVars(JCTree tree, ResultInfo resultInfo) {
mcimadamore@1348:         if (resultInfo.pt.tag == NONE || resultInfo.pt.isErroneous()) {
mcimadamore@1348:             return List.nil();
mcimadamore@1348:         } else {
mcimadamore@1348:             StuckChecker sc = new StuckChecker(resultInfo);
mcimadamore@1348:             sc.scan(tree);
mcimadamore@1348:             return List.from(sc.stuckVars);
mcimadamore@1348:         }
mcimadamore@1348:     }
mcimadamore@1348: 
mcimadamore@1348:     /**
mcimadamore@1348:      * This visitor is used to check that structural expressions conform
mcimadamore@1348:      * to their target - this step is required as inference could end up
mcimadamore@1348:      * inferring types that make some of the nested expressions incompatible
mcimadamore@1348:      * with their corresponding instantiated target
mcimadamore@1348:      */
mcimadamore@1348:     class StuckChecker extends TreeScanner {
mcimadamore@1348: 
mcimadamore@1348:         Type pt;
mcimadamore@1348:         Filter<JCTree> treeFilter;
mcimadamore@1348:         Infer.InferenceContext inferenceContext;
mcimadamore@1348:         Set<Type> stuckVars = new HashSet<Type>();
mcimadamore@1348: 
mcimadamore@1348:         final Filter<JCTree> argsFilter = new Filter<JCTree>() {
mcimadamore@1348:             public boolean accepts(JCTree t) {
mcimadamore@1348:                 switch (t.getTag()) {
mcimadamore@1348:                     case CONDEXPR:
mcimadamore@1348:                     case LAMBDA:
mcimadamore@1348:                     case PARENS:
mcimadamore@1348:                     case REFERENCE:
mcimadamore@1348:                         return true;
mcimadamore@1348:                     default:
mcimadamore@1348:                         return false;
mcimadamore@1348:                 }
mcimadamore@1348:             }
mcimadamore@1348:         };
mcimadamore@1348: 
mcimadamore@1348:         final Filter<JCTree> lambdaBodyFilter = new Filter<JCTree>() {
mcimadamore@1348:             public boolean accepts(JCTree t) {
mcimadamore@1348:                 switch (t.getTag()) {
mcimadamore@1348:                     case BLOCK: case CASE: case CATCH: case DOLOOP:
mcimadamore@1348:                     case FOREACHLOOP: case FORLOOP: case RETURN:
mcimadamore@1348:                     case SYNCHRONIZED: case SWITCH: case TRY: case WHILELOOP:
mcimadamore@1348:                         return true;
mcimadamore@1348:                     default:
mcimadamore@1348:                         return false;
mcimadamore@1348:                 }
mcimadamore@1348:             }
mcimadamore@1348:         };
mcimadamore@1348: 
mcimadamore@1348:         StuckChecker(ResultInfo resultInfo) {
mcimadamore@1348:             this.pt = resultInfo.pt;
mcimadamore@1348:             this.inferenceContext = resultInfo.checkContext.inferenceContext();
mcimadamore@1348:             this.treeFilter = argsFilter;
mcimadamore@1348:         }
mcimadamore@1348: 
mcimadamore@1348:         @Override
mcimadamore@1348:         public void scan(JCTree tree) {
mcimadamore@1348:             if (tree != null && treeFilter.accepts(tree)) {
mcimadamore@1348:                 super.scan(tree);
mcimadamore@1348:             }
mcimadamore@1348:         }
mcimadamore@1348: 
mcimadamore@1348:         @Override
mcimadamore@1348:         public void visitLambda(JCLambda tree) {
mcimadamore@1348:             Type prevPt = pt;
mcimadamore@1348:             Filter<JCTree> prevFilter = treeFilter;
mcimadamore@1348:             try {
mcimadamore@1348:                 if (inferenceContext.inferenceVars().contains(pt)) {
mcimadamore@1348:                     stuckVars.add(pt);
mcimadamore@1348:                 }
mcimadamore@1348:                 if (!types.isFunctionalInterface(pt.tsym)) {
mcimadamore@1348:                     return;
mcimadamore@1348:                 }
mcimadamore@1348:                 Type descType = types.findDescriptorType(pt);
mcimadamore@1348:                 List<Type> freeArgVars = inferenceContext.freeVarsIn(descType.getParameterTypes());
mcimadamore@1348:                 if (!TreeInfo.isExplicitLambda(tree) &&
mcimadamore@1348:                         freeArgVars.nonEmpty()) {
mcimadamore@1348:                     stuckVars.addAll(freeArgVars);
mcimadamore@1348:                 }
mcimadamore@1348:                 pt = descType.getReturnType();
mcimadamore@1348:                 if (tree.getBodyKind() == JCTree.JCLambda.BodyKind.EXPRESSION) {
mcimadamore@1348:                     scan(tree.getBody());
mcimadamore@1348:                 } else {
mcimadamore@1348:                     treeFilter = lambdaBodyFilter;
mcimadamore@1348:                     super.visitLambda(tree);
mcimadamore@1348:                 }
mcimadamore@1348:             } finally {
mcimadamore@1348:                 pt = prevPt;
mcimadamore@1348:                 treeFilter = prevFilter;
mcimadamore@1348:             }
mcimadamore@1348:         }
mcimadamore@1348: 
mcimadamore@1348:         @Override
mcimadamore@1348:         public void visitReference(JCMemberReference tree) {
mcimadamore@1348:             scan(tree.expr);
mcimadamore@1348:             if (inferenceContext.inferenceVars().contains(pt)) {
mcimadamore@1348:                 stuckVars.add(pt);
mcimadamore@1348:                 return;
mcimadamore@1348:             }
mcimadamore@1348:             if (!types.isFunctionalInterface(pt.tsym)) {
mcimadamore@1348:                 return;
mcimadamore@1348:             }
mcimadamore@1348:             Type descType = types.findDescriptorType(pt);
mcimadamore@1348:             List<Type> freeArgVars = inferenceContext.freeVarsIn(descType.getParameterTypes());
mcimadamore@1348:             stuckVars.addAll(freeArgVars);
mcimadamore@1348:         }
mcimadamore@1348: 
mcimadamore@1348:         @Override
mcimadamore@1348:         public void visitReturn(JCReturn tree) {
mcimadamore@1348:             Filter<JCTree> prevFilter = treeFilter;
mcimadamore@1348:             try {
mcimadamore@1348:                 treeFilter = argsFilter;
mcimadamore@1348:                 if (tree.expr != null) {
mcimadamore@1348:                     scan(tree.expr);
mcimadamore@1348:                 }
mcimadamore@1348:             } finally {
mcimadamore@1348:                 treeFilter = prevFilter;
mcimadamore@1348:             }
mcimadamore@1347:         }
mcimadamore@1347:     }
mcimadamore@1347: }