--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/DeferredAttr.java Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,1232 @@
+/*
+ * Copyright (c) 2012, 2017, 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 com.sun.source.tree.LambdaExpressionTree.BodyKind;
+import com.sun.source.tree.NewClassTree;
+import com.sun.tools.javac.code.*;
+import com.sun.tools.javac.code.Type.StructuralTypeMapping;
+import com.sun.tools.javac.code.Types.TypeMapping;
+import com.sun.tools.javac.comp.ArgumentAttr.LocalCacheContext;
+import com.sun.tools.javac.comp.Resolve.ResolveError;
+import com.sun.tools.javac.resources.CompilerProperties.Fragments;
+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.util.GraphUtils.DependencyKind;
+import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
+import com.sun.tools.javac.code.Symbol.*;
+import com.sun.tools.javac.comp.Attr.ResultInfo;
+import com.sun.tools.javac.comp.Resolve.MethodResolutionPhase;
+import com.sun.tools.javac.resources.CompilerProperties.Errors;
+import com.sun.tools.javac.tree.JCTree.*;
+import com.sun.tools.javac.util.JCDiagnostic.DiagnosticType;
+import com.sun.tools.javac.util.Log.DeferredDiagnosticHandler;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.WeakHashMap;
+import java.util.function.Function;
+
+import com.sun.source.tree.MemberReferenceTree;
+import com.sun.tools.javac.tree.JCTree.JCMemberReference.OverloadKind;
+
+import static com.sun.tools.javac.code.TypeTag.*;
+import static com.sun.tools.javac.tree.JCTree.Tag.*;
+
+/**
+ * This is an helper class that is used to perform deferred type-analysis.
+ * Each time a poly expression occurs in argument position, javac attributes it
+ * with a temporary 'deferred type' that is checked (possibly multiple times)
+ * against an expected formal type.
+ *
+ * <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 DeferredAttr extends JCTree.Visitor {
+ protected static final Context.Key<DeferredAttr> deferredAttrKey = new Context.Key<>();
+
+ final Attr attr;
+ final ArgumentAttr argumentAttr;
+ final Check chk;
+ final JCDiagnostic.Factory diags;
+ final Enter enter;
+ final Infer infer;
+ final Resolve rs;
+ final Log log;
+ final Symtab syms;
+ final TreeMaker make;
+ final TreeCopier<Void> treeCopier;
+ final TypeMapping<Void> deferredCopier;
+ final Types types;
+ final Flow flow;
+ final Names names;
+ final TypeEnvs typeEnvs;
+
+ public static DeferredAttr instance(Context context) {
+ DeferredAttr instance = context.get(deferredAttrKey);
+ if (instance == null)
+ instance = new DeferredAttr(context);
+ return instance;
+ }
+
+ protected DeferredAttr(Context context) {
+ context.put(deferredAttrKey, this);
+ attr = Attr.instance(context);
+ argumentAttr = ArgumentAttr.instance(context);
+ chk = Check.instance(context);
+ diags = JCDiagnostic.Factory.instance(context);
+ enter = Enter.instance(context);
+ infer = Infer.instance(context);
+ rs = Resolve.instance(context);
+ log = Log.instance(context);
+ syms = Symtab.instance(context);
+ make = TreeMaker.instance(context);
+ types = Types.instance(context);
+ flow = Flow.instance(context);
+ names = Names.instance(context);
+ stuckTree = make.Ident(names.empty).setType(Type.stuckType);
+ typeEnvs = TypeEnvs.instance(context);
+ emptyDeferredAttrContext =
+ new DeferredAttrContext(AttrMode.CHECK, null, MethodResolutionPhase.BOX, infer.emptyContext, null, null) {
+ @Override
+ void addDeferredAttrNode(DeferredType dt, ResultInfo ri, DeferredStuckPolicy deferredStuckPolicy) {
+ Assert.error("Empty deferred context!");
+ }
+ @Override
+ void complete() {
+ Assert.error("Empty deferred context!");
+ }
+
+ @Override
+ public String toString() {
+ return "Empty deferred context!";
+ }
+ };
+
+ // For speculative attribution, skip the class definition in <>.
+ treeCopier =
+ new TreeCopier<Void>(make) {
+ @Override @DefinedBy(Api.COMPILER_TREE)
+ public JCTree visitNewClass(NewClassTree node, Void p) {
+ JCNewClass t = (JCNewClass) node;
+ if (TreeInfo.isDiamond(t)) {
+ JCExpression encl = copy(t.encl, p);
+ List<JCExpression> typeargs = copy(t.typeargs, p);
+ JCExpression clazz = copy(t.clazz, p);
+ List<JCExpression> args = copy(t.args, p);
+ JCClassDecl def = null;
+ return make.at(t.pos).NewClass(encl, typeargs, clazz, args, def);
+ } else {
+ return super.visitNewClass(node, p);
+ }
+ }
+
+ @Override @DefinedBy(Api.COMPILER_TREE)
+ public JCTree visitMemberReference(MemberReferenceTree node, Void p) {
+ JCMemberReference t = (JCMemberReference) node;
+ JCExpression expr = copy(t.expr, p);
+ List<JCExpression> typeargs = copy(t.typeargs, p);
+ /** once the value for overloadKind is determined for a copy, it can be safely forwarded to
+ * the copied tree, we want to profit from that
+ */
+ JCMemberReference result = new JCMemberReference(t.mode, t.name, expr, typeargs) {
+ @Override
+ public void setOverloadKind(OverloadKind overloadKind) {
+ super.setOverloadKind(overloadKind);
+ if (t.getOverloadKind() == null) {
+ t.setOverloadKind(overloadKind);
+ }
+ }
+ };
+ result.pos = t.pos;
+ return result;
+ }
+ };
+ deferredCopier = new TypeMapping<Void> () {
+ @Override
+ public Type visitType(Type t, Void v) {
+ if (t.hasTag(DEFERRED)) {
+ DeferredType dt = (DeferredType) t;
+ return new DeferredType(treeCopier.copy(dt.tree), dt.env);
+ }
+ return t;
+ }
+ };
+ }
+
+ /** shared tree for stuck expressions */
+ final JCTree stuckTree;
+
+ /**
+ * This type represents a deferred type. A deferred type starts off with
+ * no information on the underlying expression type. Such info needs to be
+ * discovered through type-checking the deferred type against a target-type.
+ * Every deferred type keeps a pointer to the AST node from which it originated.
+ */
+ public class DeferredType extends Type {
+
+ public JCExpression tree;
+ Env<AttrContext> env;
+ AttrMode mode;
+ boolean pertinentToApplicability = true;
+ SpeculativeCache speculativeCache;
+
+ DeferredType(JCExpression tree, Env<AttrContext> env) {
+ super(null, TypeMetadata.EMPTY);
+ this.tree = tree;
+ this.env = attr.copyEnv(env);
+ this.speculativeCache = new SpeculativeCache();
+ }
+
+ @Override
+ public DeferredType cloneWithMetadata(TypeMetadata md) {
+ throw new AssertionError("Cannot add metadata to a deferred type");
+ }
+
+ @Override
+ public TypeTag getTag() {
+ return DEFERRED;
+ }
+
+ @Override @DefinedBy(Api.LANGUAGE_MODEL)
+ public String toString() {
+ return "DeferredType";
+ }
+
+ /**
+ * A speculative cache is used to keep track of all overload resolution rounds
+ * that triggered speculative attribution on a given deferred type. Each entry
+ * stores a pointer to the speculative tree and the resolution phase in which the entry
+ * has been added.
+ */
+ class SpeculativeCache {
+
+ private Map<Symbol, List<Entry>> cache = new WeakHashMap<>();
+
+ class Entry {
+ JCTree speculativeTree;
+ ResultInfo resultInfo;
+
+ public Entry(JCTree speculativeTree, ResultInfo resultInfo) {
+ this.speculativeTree = speculativeTree;
+ this.resultInfo = resultInfo;
+ }
+
+ boolean matches(MethodResolutionPhase phase) {
+ return resultInfo.checkContext.deferredAttrContext().phase == phase;
+ }
+ }
+
+ /**
+ * Retrieve a speculative cache entry corresponding to given symbol
+ * and resolution phase
+ */
+ Entry get(Symbol msym, MethodResolutionPhase phase) {
+ List<Entry> entries = cache.get(msym);
+ if (entries == null) return null;
+ for (Entry e : entries) {
+ if (e.matches(phase)) return e;
+ }
+ return null;
+ }
+
+ /**
+ * Stores a speculative cache entry corresponding to given symbol
+ * and resolution phase
+ */
+ void put(JCTree speculativeTree, ResultInfo resultInfo) {
+ Symbol msym = resultInfo.checkContext.deferredAttrContext().msym;
+ List<Entry> entries = cache.get(msym);
+ if (entries == null) {
+ entries = List.nil();
+ }
+ cache.put(msym, entries.prepend(new Entry(speculativeTree, resultInfo)));
+ }
+ }
+
+ /**
+ * Get the type that has been computed during a speculative attribution round
+ */
+ Type speculativeType(Symbol msym, MethodResolutionPhase phase) {
+ SpeculativeCache.Entry e = speculativeCache.get(msym, phase);
+ return e != null ? e.speculativeTree.type : Type.noType;
+ }
+
+ JCTree speculativeTree(DeferredAttrContext deferredAttrContext) {
+ DeferredType.SpeculativeCache.Entry e = speculativeCache.get(deferredAttrContext.msym, deferredAttrContext.phase);
+ return e != null ? e.speculativeTree : stuckTree;
+ }
+
+ DeferredTypeCompleter completer() {
+ return basicCompleter;
+ }
+
+ /**
+ * Check a deferred type against a potential target-type. Depending on
+ * the current attribution mode, a normal vs. speculative attribution
+ * round is performed on the underlying AST node. There can be only one
+ * speculative round for a given target method symbol; moreover, a normal
+ * attribution round must follow one or more speculative rounds.
+ */
+ Type check(ResultInfo resultInfo) {
+ DeferredStuckPolicy deferredStuckPolicy;
+ if (resultInfo.pt.hasTag(NONE) || resultInfo.pt.isErroneous()) {
+ deferredStuckPolicy = dummyStuckPolicy;
+ } else if (resultInfo.checkContext.deferredAttrContext().mode == AttrMode.SPECULATIVE ||
+ resultInfo.checkContext.deferredAttrContext().insideOverloadPhase()) {
+ deferredStuckPolicy = new OverloadStuckPolicy(resultInfo, this);
+ } else {
+ deferredStuckPolicy = new CheckStuckPolicy(resultInfo, this);
+ }
+ return check(resultInfo, deferredStuckPolicy, completer());
+ }
+
+ private Type check(ResultInfo resultInfo, DeferredStuckPolicy deferredStuckPolicy,
+ DeferredTypeCompleter deferredTypeCompleter) {
+ DeferredAttrContext deferredAttrContext =
+ resultInfo.checkContext.deferredAttrContext();
+ Assert.check(deferredAttrContext != emptyDeferredAttrContext);
+ if (deferredStuckPolicy.isStuck()) {
+ pertinentToApplicability = false;
+ deferredAttrContext.addDeferredAttrNode(this, resultInfo, deferredStuckPolicy);
+ return Type.noType;
+ } else {
+ try {
+ return deferredTypeCompleter.complete(this, resultInfo, deferredAttrContext);
+ } finally {
+ mode = deferredAttrContext.mode;
+ }
+ }
+ }
+ }
+
+ /**
+ * A completer for deferred types. Defines an entry point for type-checking
+ * a deferred type.
+ */
+ interface DeferredTypeCompleter {
+ /**
+ * Entry point for type-checking a deferred type. Depending on the
+ * circumstances, type-checking could amount to full attribution
+ * or partial structural check (aka potential applicability).
+ */
+ Type complete(DeferredType dt, ResultInfo resultInfo, DeferredAttrContext deferredAttrContext);
+ }
+
+
+ /**
+ * A basic completer for deferred types. This completer type-checks a deferred type
+ * using attribution; depending on the attribution mode, this could be either standard
+ * or speculative attribution.
+ */
+ DeferredTypeCompleter basicCompleter = new DeferredTypeCompleter() {
+ public Type complete(DeferredType dt, ResultInfo resultInfo, DeferredAttrContext deferredAttrContext) {
+ switch (deferredAttrContext.mode) {
+ case SPECULATIVE:
+ //Note: if a symbol is imported twice we might do two identical
+ //speculative rounds...
+ Assert.check(dt.mode == null || dt.mode == AttrMode.SPECULATIVE);
+ JCTree speculativeTree = attribSpeculative(dt.tree, dt.env, resultInfo);
+ dt.speculativeCache.put(speculativeTree, resultInfo);
+ return speculativeTree.type;
+ case CHECK:
+ Assert.check(dt.mode != null);
+ return attr.attribTree(dt.tree, dt.env, resultInfo);
+ }
+ Assert.error();
+ return null;
+ }
+ };
+
+ /**
+ * Policy for detecting stuck expressions. Different criteria might cause
+ * an expression to be judged as stuck, depending on whether the check
+ * is performed during overload resolution or after most specific.
+ */
+ interface DeferredStuckPolicy {
+ /**
+ * Has the policy detected that a given expression should be considered stuck?
+ */
+ boolean isStuck();
+ /**
+ * Get the set of inference variables a given expression depends upon.
+ */
+ Set<Type> stuckVars();
+ /**
+ * Get the set of inference variables which might get new constraints
+ * if a given expression is being type-checked.
+ */
+ Set<Type> depVars();
+ }
+
+ /**
+ * Basic stuck policy; an expression is never considered to be stuck.
+ */
+ DeferredStuckPolicy dummyStuckPolicy = new DeferredStuckPolicy() {
+ @Override
+ public boolean isStuck() {
+ return false;
+ }
+ @Override
+ public Set<Type> stuckVars() {
+ return Collections.emptySet();
+ }
+ @Override
+ public Set<Type> depVars() {
+ return Collections.emptySet();
+ }
+ };
+
+ /**
+ * The 'mode' in which the deferred type is to be type-checked
+ */
+ public enum AttrMode {
+ /**
+ * A speculative type-checking round is used during overload resolution
+ * mainly to generate constraints on inference variables. Side-effects
+ * arising from type-checking the expression associated with the deferred
+ * type are reversed after the speculative round finishes. This means the
+ * expression tree will be left in a blank state.
+ */
+ SPECULATIVE,
+ /**
+ * This is the plain type-checking mode. Produces side-effects on the underlying AST node
+ */
+ CHECK
+ }
+
+ /**
+ * Performs speculative attribution of a lambda body and returns the speculative lambda tree,
+ * in the absence of a target-type. Since {@link Attr#visitLambda(JCLambda)} cannot type-check
+ * lambda bodies w/o a suitable target-type, this routine 'unrolls' the lambda by turning it
+ * into a regular block, speculatively type-checks the block and then puts back the pieces.
+ */
+ JCLambda attribSpeculativeLambda(JCLambda that, Env<AttrContext> env, ResultInfo resultInfo) {
+ ListBuffer<JCStatement> stats = new ListBuffer<>();
+ stats.addAll(that.params);
+ if (that.getBodyKind() == JCLambda.BodyKind.EXPRESSION) {
+ stats.add(make.Return((JCExpression)that.body));
+ } else {
+ stats.add((JCBlock)that.body);
+ }
+ JCBlock lambdaBlock = make.Block(0, stats.toList());
+ Env<AttrContext> localEnv = attr.lambdaEnv(that, env);
+ try {
+ localEnv.info.returnResult = resultInfo;
+ JCBlock speculativeTree = (JCBlock)attribSpeculative(lambdaBlock, localEnv, resultInfo);
+ List<JCVariableDecl> args = speculativeTree.getStatements().stream()
+ .filter(s -> s.hasTag(Tag.VARDEF))
+ .map(t -> (JCVariableDecl)t)
+ .collect(List.collector());
+ JCTree lambdaBody = speculativeTree.getStatements().last();
+ if (lambdaBody.hasTag(Tag.RETURN)) {
+ lambdaBody = ((JCReturn)lambdaBody).expr;
+ }
+ JCLambda speculativeLambda = make.Lambda(args, lambdaBody);
+ attr.preFlow(speculativeLambda);
+ flow.analyzeLambda(env, speculativeLambda, make, false);
+ return speculativeLambda;
+ } finally {
+ localEnv.info.scope.leave();
+ }
+ }
+
+ /**
+ * Routine that performs speculative type-checking; the input AST node is
+ * cloned (to avoid side-effects cause by Attr) and compiler state is
+ * restored after type-checking. All diagnostics (but critical ones) are
+ * disabled during speculative type-checking.
+ */
+ JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo) {
+ return attribSpeculative(tree, env, resultInfo, treeCopier,
+ (newTree)->new DeferredAttrDiagHandler(log, newTree), null);
+ }
+
+ JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo, LocalCacheContext localCache) {
+ return attribSpeculative(tree, env, resultInfo, treeCopier,
+ (newTree)->new DeferredAttrDiagHandler(log, newTree), localCache);
+ }
+
+ <Z> JCTree attribSpeculative(JCTree tree, Env<AttrContext> env, ResultInfo resultInfo, TreeCopier<Z> deferredCopier,
+ Function<JCTree, DeferredDiagnosticHandler> diagHandlerCreator,
+ LocalCacheContext localCache) {
+ final JCTree newTree = deferredCopier.copy(tree);
+ Env<AttrContext> speculativeEnv = env.dup(newTree, env.info.dup(env.info.scope.dupUnshared(env.info.scope.owner)));
+ speculativeEnv.info.isSpeculative = true;
+ Log.DeferredDiagnosticHandler deferredDiagnosticHandler = diagHandlerCreator.apply(newTree);
+ try {
+ attr.attribTree(newTree, speculativeEnv, resultInfo);
+ return newTree;
+ } finally {
+ new UnenterScanner(env.toplevel.modle).scan(newTree);
+ log.popDiagnosticHandler(deferredDiagnosticHandler);
+ if (localCache != null) {
+ localCache.leave();
+ }
+ }
+ }
+ //where
+
+ class UnenterScanner extends TreeScanner {
+ private final ModuleSymbol msym;
+
+ public UnenterScanner(ModuleSymbol msym) {
+ this.msym = msym;
+ }
+
+ @Override
+ public void visitClassDef(JCClassDecl tree) {
+ ClassSymbol csym = tree.sym;
+ //if something went wrong during method applicability check
+ //it is possible that nested expressions inside argument expression
+ //are left unchecked - in such cases there's nothing to clean up.
+ if (csym == null) return;
+ typeEnvs.remove(csym);
+ chk.removeCompiled(csym);
+ chk.clearLocalClassNameIndexes(csym);
+ syms.removeClass(msym, csym.flatname);
+ super.visitClassDef(tree);
+ }
+ }
+
+ static class DeferredAttrDiagHandler extends Log.DeferredDiagnosticHandler {
+
+ static class PosScanner extends TreeScanner {
+ DiagnosticPosition pos;
+ boolean found = false;
+
+ PosScanner(DiagnosticPosition pos) {
+ this.pos = pos;
+ }
+
+ @Override
+ public void scan(JCTree tree) {
+ if (tree != null &&
+ tree.pos() == pos) {
+ found = true;
+ }
+ super.scan(tree);
+ }
+ }
+
+ DeferredAttrDiagHandler(Log log, JCTree newTree) {
+ super(log, d -> {
+ PosScanner posScanner = new PosScanner(d.getDiagnosticPosition());
+ posScanner.scan(newTree);
+ return posScanner.found;
+ });
+ }
+ }
+
+ /**
+ * A deferred context is created on each method check. A deferred context is
+ * used to keep track of information associated with the method check, such as
+ * the symbol of the method being checked, the overload resolution phase,
+ * the kind of attribution mode to be applied to deferred types and so forth.
+ * As deferred types are processed (by the method check routine) stuck AST nodes
+ * are added (as new deferred attribution nodes) to this context. The complete()
+ * routine makes sure that all pending nodes are properly processed, by
+ * progressively instantiating all inference variables on which one or more
+ * deferred attribution node is stuck.
+ */
+ class DeferredAttrContext {
+
+ /** attribution mode */
+ final AttrMode mode;
+
+ /** symbol of the method being checked */
+ final Symbol msym;
+
+ /** method resolution step */
+ final Resolve.MethodResolutionPhase phase;
+
+ /** inference context */
+ final InferenceContext inferenceContext;
+
+ /** parent deferred context */
+ final DeferredAttrContext parent;
+
+ /** Warner object to report warnings */
+ final Warner warn;
+
+ /** list of deferred attribution nodes to be processed */
+ ArrayList<DeferredAttrNode> deferredAttrNodes = new ArrayList<>();
+
+ DeferredAttrContext(AttrMode mode, Symbol msym, MethodResolutionPhase phase,
+ InferenceContext inferenceContext, DeferredAttrContext parent, Warner warn) {
+ this.mode = mode;
+ this.msym = msym;
+ this.phase = phase;
+ this.parent = parent;
+ this.warn = warn;
+ this.inferenceContext = inferenceContext;
+ }
+
+ /**
+ * Adds a node to the list of deferred attribution nodes - used by Resolve.rawCheckArgumentsApplicable
+ * Nodes added this way act as 'roots' for the out-of-order method checking process.
+ */
+ void addDeferredAttrNode(final DeferredType dt, ResultInfo resultInfo,
+ DeferredStuckPolicy deferredStuckPolicy) {
+ deferredAttrNodes.add(new DeferredAttrNode(dt, resultInfo, deferredStuckPolicy));
+ }
+
+ /**
+ * Incrementally process all nodes, by skipping 'stuck' nodes and attributing
+ * 'unstuck' ones. If at any point no progress can be made (no 'unstuck' nodes)
+ * some inference variable might get eagerly instantiated so that all nodes
+ * can be type-checked.
+ */
+ void complete() {
+ while (!deferredAttrNodes.isEmpty()) {
+ boolean progress = false;
+ //scan a defensive copy of the node list - this is because a deferred
+ //attribution round can add new nodes to the list
+ for (DeferredAttrNode deferredAttrNode : List.from(deferredAttrNodes)) {
+ if (deferredAttrNode.process(this)) {
+ deferredAttrNodes.remove(deferredAttrNode);
+ progress = true;
+ }
+ }
+ if (!progress) {
+ if (insideOverloadPhase()) {
+ for (DeferredAttrNode deferredNode: deferredAttrNodes) {
+ deferredNode.dt.tree.type = Type.noType;
+ }
+ return;
+ }
+ //remove all variables that have already been instantiated
+ //from the list of stuck variables
+ try {
+ //find stuck expression to unstuck
+ DeferredAttrNode toUnstuck = pickDeferredNode();
+ inferenceContext.solveAny(List.from(toUnstuck.deferredStuckPolicy.stuckVars()), warn);
+ inferenceContext.notifyChange();
+ } catch (Infer.GraphStrategy.NodeNotFoundException ex) {
+ //this means that we are in speculative mode and the
+ //set of contraints are too tight for progess to be made.
+ //Just leave the remaining expressions as stuck.
+ break;
+ }
+ }
+ }
+ }
+
+ public boolean insideOverloadPhase() {
+ DeferredAttrContext dac = this;
+ if (dac == emptyDeferredAttrContext) {
+ return false;
+ }
+ if (dac.mode == AttrMode.SPECULATIVE) {
+ return true;
+ }
+ return dac.parent.insideOverloadPhase();
+ }
+
+ /**
+ * Pick the deferred node to be unstuck. The chosen node is the first strongly connected
+ * component containing exactly one node found in the dependency graph induced by deferred nodes.
+ * If no such component is found, the first deferred node is returned.
+ */
+ DeferredAttrNode pickDeferredNode() {
+ List<StuckNode> nodes = deferredAttrNodes.stream()
+ .map(StuckNode::new)
+ .collect(List.collector());
+ //init stuck expression graph; a deferred node A depends on a deferred node B iff
+ //the intersection between A's input variable and B's output variable is non-empty.
+ for (StuckNode sn1 : nodes) {
+ for (Type t : sn1.data.deferredStuckPolicy.stuckVars()) {
+ for (StuckNode sn2 : nodes) {
+ if (sn1 != sn2 && sn2.data.deferredStuckPolicy.depVars().contains(t)) {
+ sn1.deps.add(sn2);
+ }
+ }
+ }
+ }
+ //compute tarjan on the stuck graph
+ List<? extends StuckNode> csn = GraphUtils.tarjan(nodes).get(0);
+ return csn.length() == 1 ? csn.get(0).data : deferredAttrNodes.get(0);
+ }
+
+ class StuckNode extends GraphUtils.TarjanNode<DeferredAttrNode, StuckNode> {
+
+ Set<StuckNode> deps = new HashSet<>();
+
+ StuckNode(DeferredAttrNode data) {
+ super(data);
+ }
+
+ @Override
+ public DependencyKind[] getSupportedDependencyKinds() {
+ return new DependencyKind[] { Infer.DependencyKind.STUCK };
+ }
+
+ @Override
+ public Collection<? extends StuckNode> getDependenciesByKind(DependencyKind dk) {
+ if (dk == Infer.DependencyKind.STUCK) {
+ return deps;
+ } else {
+ throw new IllegalStateException();
+ }
+ }
+
+ @Override
+ public Iterable<? extends StuckNode> getAllDependencies() {
+ return deps;
+ }
+ }
+ }
+
+ /**
+ * Class representing a deferred attribution node. It keeps track of
+ * a deferred type, along with the expected target type information.
+ */
+ class DeferredAttrNode {
+
+ /** underlying deferred type */
+ DeferredType dt;
+
+ /** underlying target type information */
+ ResultInfo resultInfo;
+
+ /** stuck policy associated with this node */
+ DeferredStuckPolicy deferredStuckPolicy;
+
+ DeferredAttrNode(DeferredType dt, ResultInfo resultInfo, DeferredStuckPolicy deferredStuckPolicy) {
+ this.dt = dt;
+ this.resultInfo = resultInfo;
+ this.deferredStuckPolicy = deferredStuckPolicy;
+ }
+
+ /**
+ * Process a deferred attribution node.
+ * Invariant: a stuck node cannot be processed.
+ */
+ @SuppressWarnings("fallthrough")
+ boolean process(final DeferredAttrContext deferredAttrContext) {
+ switch (deferredAttrContext.mode) {
+ case SPECULATIVE:
+ if (deferredStuckPolicy.isStuck()) {
+ dt.check(resultInfo, dummyStuckPolicy, new StructuralStuckChecker());
+ return true;
+ } else {
+ Assert.error("Cannot get here");
+ }
+ case CHECK:
+ if (deferredStuckPolicy.isStuck()) {
+ //stuck expression - see if we can propagate
+ if (deferredAttrContext.parent != emptyDeferredAttrContext &&
+ Type.containsAny(deferredAttrContext.parent.inferenceContext.inferencevars,
+ List.from(deferredStuckPolicy.stuckVars()))) {
+ deferredAttrContext.parent.addDeferredAttrNode(dt,
+ resultInfo.dup(new Check.NestedCheckContext(resultInfo.checkContext) {
+ @Override
+ public InferenceContext inferenceContext() {
+ return deferredAttrContext.parent.inferenceContext;
+ }
+ @Override
+ public DeferredAttrContext deferredAttrContext() {
+ return deferredAttrContext.parent;
+ }
+ }), deferredStuckPolicy);
+ dt.tree.type = Type.stuckType;
+ return true;
+ } else {
+ return false;
+ }
+ } else {
+ Assert.check(!deferredAttrContext.insideOverloadPhase(),
+ "attribution shouldn't be happening here");
+ ResultInfo instResultInfo =
+ resultInfo.dup(deferredAttrContext.inferenceContext.asInstType(resultInfo.pt));
+ dt.check(instResultInfo, dummyStuckPolicy, basicCompleter);
+ return true;
+ }
+ default:
+ throw new AssertionError("Bad mode");
+ }
+ }
+
+ /**
+ * Structural checker for stuck expressions
+ */
+ class StructuralStuckChecker extends TreeScanner implements DeferredTypeCompleter {
+
+ ResultInfo resultInfo;
+ InferenceContext inferenceContext;
+ Env<AttrContext> env;
+
+ public Type complete(DeferredType dt, ResultInfo resultInfo, DeferredAttrContext deferredAttrContext) {
+ this.resultInfo = resultInfo;
+ this.inferenceContext = deferredAttrContext.inferenceContext;
+ this.env = dt.env;
+ dt.tree.accept(this);
+ dt.speculativeCache.put(stuckTree, resultInfo);
+ return Type.noType;
+ }
+
+ @Override
+ public void visitLambda(JCLambda tree) {
+ Check.CheckContext checkContext = resultInfo.checkContext;
+ Type pt = resultInfo.pt;
+ if (!inferenceContext.inferencevars.contains(pt)) {
+ //must be a functional descriptor
+ Type descriptorType = null;
+ try {
+ descriptorType = types.findDescriptorType(pt);
+ } catch (Types.FunctionDescriptorLookupError ex) {
+ checkContext.report(null, ex.getDiagnostic());
+ }
+
+ if (descriptorType.getParameterTypes().length() != tree.params.length()) {
+ checkContext.report(tree,
+ diags.fragment(Fragments.IncompatibleArgTypesInLambda));
+ }
+
+ Type currentReturnType = descriptorType.getReturnType();
+ boolean returnTypeIsVoid = currentReturnType.hasTag(VOID);
+ if (tree.getBodyKind() == BodyKind.EXPRESSION) {
+ boolean isExpressionCompatible = !returnTypeIsVoid ||
+ TreeInfo.isExpressionStatement((JCExpression)tree.getBody());
+ if (!isExpressionCompatible) {
+ resultInfo.checkContext.report(tree.pos(),
+ diags.fragment(Fragments.IncompatibleRetTypeInLambda(Fragments.MissingRetVal(currentReturnType))));
+ }
+ } else {
+ LambdaBodyStructChecker lambdaBodyChecker =
+ new LambdaBodyStructChecker();
+
+ tree.body.accept(lambdaBodyChecker);
+ boolean isVoidCompatible = lambdaBodyChecker.isVoidCompatible;
+
+ if (returnTypeIsVoid) {
+ if (!isVoidCompatible) {
+ resultInfo.checkContext.report(tree.pos(),
+ diags.fragment(Fragments.UnexpectedRetVal));
+ }
+ } else {
+ boolean isValueCompatible = lambdaBodyChecker.isPotentiallyValueCompatible
+ && !canLambdaBodyCompleteNormally(tree);
+ if (!isValueCompatible && !isVoidCompatible) {
+ log.error(tree.body.pos(),
+ Errors.LambdaBodyNeitherValueNorVoidCompatible);
+ }
+
+ if (!isValueCompatible) {
+ resultInfo.checkContext.report(tree.pos(),
+ diags.fragment(Fragments.IncompatibleRetTypeInLambda(Fragments.MissingRetVal(currentReturnType))));
+ }
+ }
+ }
+ }
+ }
+
+ boolean canLambdaBodyCompleteNormally(JCLambda tree) {
+ List<JCVariableDecl> oldParams = tree.params;
+ LocalCacheContext localCacheContext = argumentAttr.withLocalCacheContext();
+ try {
+ tree.params = tree.params.stream()
+ .map(vd -> make.VarDef(vd.mods, vd.name, make.Erroneous(), null))
+ .collect(List.collector());
+ return attribSpeculativeLambda(tree, env, attr.unknownExprInfo).canCompleteNormally;
+ } finally {
+ localCacheContext.leave();
+ tree.params = oldParams;
+ }
+ }
+
+ @Override
+ public void visitNewClass(JCNewClass tree) {
+ //do nothing
+ }
+
+ @Override
+ public void visitApply(JCMethodInvocation tree) {
+ //do nothing
+ }
+
+ @Override
+ public void visitReference(JCMemberReference tree) {
+ Assert.checkNonNull(tree.getOverloadKind());
+ Check.CheckContext checkContext = resultInfo.checkContext;
+ Type pt = resultInfo.pt;
+ if (!inferenceContext.inferencevars.contains(pt)) {
+ try {
+ types.findDescriptorType(pt);
+ } catch (Types.FunctionDescriptorLookupError ex) {
+ checkContext.report(null, ex.getDiagnostic());
+ }
+ Env<AttrContext> localEnv = env.dup(tree);
+ JCExpression exprTree;
+ exprTree = (JCExpression)attribSpeculative(tree.getQualifierExpression(), localEnv,
+ attr.memberReferenceQualifierResult(tree), argumentAttr.withLocalCacheContext());
+ ListBuffer<Type> argtypes = new ListBuffer<>();
+ for (Type t : types.findDescriptorType(pt).getParameterTypes()) {
+ argtypes.append(Type.noType);
+ }
+ JCMemberReference mref2 = new TreeCopier<Void>(make).copy(tree);
+ mref2.expr = exprTree;
+ Symbol lookupSym =
+ rs.resolveMemberReference(localEnv, mref2, exprTree.type,
+ tree.name, argtypes.toList(), List.nil(), rs.arityMethodCheck,
+ inferenceContext, rs.structuralReferenceChooser).fst;
+ switch (lookupSym.kind) {
+ case WRONG_MTH:
+ case WRONG_MTHS:
+ //note: as argtypes are erroneous types, type-errors must
+ //have been caused by arity mismatch
+ checkContext.report(tree, diags.fragment(Fragments.IncompatibleArgTypesInMref));
+ break;
+ case ABSENT_MTH:
+ case STATICERR:
+ //if no method found, or method found with wrong staticness, report better message
+ checkContext.report(tree, ((ResolveError)lookupSym).getDiagnostic(DiagnosticType.FRAGMENT,
+ tree, exprTree.type.tsym, exprTree.type, tree.name, argtypes.toList(), List.nil()));
+ break;
+ }
+ }
+ }
+ }
+
+ /* This visitor looks for return statements, its analysis will determine if
+ * a lambda body is void or value compatible. We must analyze return
+ * statements contained in the lambda body only, thus any return statement
+ * contained in an inner class or inner lambda body, should be ignored.
+ */
+ class LambdaBodyStructChecker extends TreeScanner {
+ boolean isVoidCompatible = true;
+ boolean isPotentiallyValueCompatible = true;
+
+ @Override
+ public void visitClassDef(JCClassDecl tree) {
+ // do nothing
+ }
+
+ @Override
+ public void visitLambda(JCLambda tree) {
+ // do nothing
+ }
+
+ @Override
+ public void visitNewClass(JCNewClass tree) {
+ // do nothing
+ }
+
+ @Override
+ public void visitReturn(JCReturn tree) {
+ if (tree.expr != null) {
+ isVoidCompatible = false;
+ } else {
+ isPotentiallyValueCompatible = false;
+ }
+ }
+ }
+ }
+
+ /** an empty deferred attribution context - all methods throw exceptions */
+ final DeferredAttrContext emptyDeferredAttrContext;
+
+ /**
+ * Map a list of types possibly containing one or more deferred types
+ * into a list of ordinary types. Each deferred type D is mapped into a type T,
+ * where T is computed by retrieving the type that has already been
+ * computed for D during a previous deferred attribution round of the given kind.
+ */
+ class DeferredTypeMap extends StructuralTypeMapping<Void> {
+ DeferredAttrContext deferredAttrContext;
+
+ protected DeferredTypeMap(AttrMode mode, Symbol msym, MethodResolutionPhase phase) {
+ this.deferredAttrContext = new DeferredAttrContext(mode, msym, phase,
+ infer.emptyContext, emptyDeferredAttrContext, types.noWarnings);
+ }
+
+ @Override
+ public Type visitType(Type t, Void _unused) {
+ if (!t.hasTag(DEFERRED)) {
+ return super.visitType(t, null);
+ } else {
+ DeferredType dt = (DeferredType)t;
+ return typeOf(dt);
+ }
+ }
+
+ protected Type typeOf(DeferredType dt) {
+ switch (deferredAttrContext.mode) {
+ case CHECK:
+ return dt.tree.type == null ? Type.noType : dt.tree.type;
+ case SPECULATIVE:
+ return dt.speculativeType(deferredAttrContext.msym, deferredAttrContext.phase);
+ }
+ Assert.error();
+ return null;
+ }
+ }
+
+ /**
+ * Specialized recovery deferred mapping.
+ * Each deferred type D is mapped into a type T, where T is computed either by
+ * (i) retrieving the type that has already been computed for D during a previous
+ * attribution round (as before), or (ii) by synthesizing a new type R for D
+ * (the latter step is useful in a recovery scenario).
+ */
+ public class RecoveryDeferredTypeMap extends DeferredTypeMap {
+
+ public RecoveryDeferredTypeMap(AttrMode mode, Symbol msym, MethodResolutionPhase phase) {
+ super(mode, msym, phase != null ? phase : MethodResolutionPhase.BOX);
+ }
+
+ @Override
+ protected Type typeOf(DeferredType dt) {
+ Type owntype = super.typeOf(dt);
+ return owntype == Type.noType ?
+ recover(dt) : owntype;
+ }
+
+ /**
+ * Synthesize a type for a deferred type that hasn't been previously
+ * reduced to an ordinary type. Functional deferred types and conditionals
+ * are mapped to themselves, in order to have a richer diagnostic
+ * representation. Remaining deferred types are attributed using
+ * a default expected type (j.l.Object).
+ */
+ private Type recover(DeferredType dt) {
+ dt.check(attr.new RecoveryInfo(deferredAttrContext) {
+ @Override
+ protected Type check(DiagnosticPosition pos, Type found) {
+ return chk.checkNonVoid(pos, super.check(pos, found));
+ }
+ });
+ return super.visit(dt);
+ }
+ }
+
+ /**
+ * A special tree scanner that would only visit portions of a given tree.
+ * The set of nodes visited by the scanner can be customized at construction-time.
+ */
+ abstract static class FilterScanner extends com.sun.tools.javac.tree.TreeScanner {
+
+ final Filter<JCTree> treeFilter;
+
+ FilterScanner(final Set<JCTree.Tag> validTags) {
+ this.treeFilter = t -> validTags.contains(t.getTag());
+ }
+
+ @Override
+ public void scan(JCTree tree) {
+ if (tree != null) {
+ if (treeFilter.accepts(tree)) {
+ super.scan(tree);
+ } else {
+ skip(tree);
+ }
+ }
+ }
+
+ /**
+ * handler that is executed when a node has been discarded
+ */
+ void skip(JCTree tree) {}
+ }
+
+ /**
+ * A tree scanner suitable for visiting the target-type dependent nodes of
+ * a given argument expression.
+ */
+ static class PolyScanner extends FilterScanner {
+
+ PolyScanner() {
+ super(EnumSet.of(CONDEXPR, PARENS, LAMBDA, REFERENCE));
+ }
+ }
+
+ /**
+ * A tree scanner suitable for visiting the target-type dependent nodes nested
+ * within a lambda expression body.
+ */
+ static class LambdaReturnScanner extends FilterScanner {
+
+ LambdaReturnScanner() {
+ super(EnumSet.of(BLOCK, CASE, CATCH, DOLOOP, FOREACHLOOP,
+ FORLOOP, IF, RETURN, SYNCHRONIZED, SWITCH, TRY, WHILELOOP));
+ }
+ }
+
+ /**
+ * This visitor is used to check that structural expressions conform
+ * to their target - this step is required as inference could end up
+ * inferring types that make some of the nested expressions incompatible
+ * with their corresponding instantiated target
+ */
+ class CheckStuckPolicy extends PolyScanner implements DeferredStuckPolicy, Infer.FreeTypeListener {
+
+ Type pt;
+ InferenceContext inferenceContext;
+ Set<Type> stuckVars = new LinkedHashSet<>();
+ Set<Type> depVars = new LinkedHashSet<>();
+
+ @Override
+ public boolean isStuck() {
+ return !stuckVars.isEmpty();
+ }
+
+ @Override
+ public Set<Type> stuckVars() {
+ return stuckVars;
+ }
+
+ @Override
+ public Set<Type> depVars() {
+ return depVars;
+ }
+
+ public CheckStuckPolicy(ResultInfo resultInfo, DeferredType dt) {
+ this.pt = resultInfo.pt;
+ this.inferenceContext = resultInfo.checkContext.inferenceContext();
+ scan(dt.tree);
+ if (!stuckVars.isEmpty()) {
+ resultInfo.checkContext.inferenceContext()
+ .addFreeTypeListener(List.from(stuckVars), this);
+ }
+ }
+
+ @Override
+ public void typesInferred(InferenceContext inferenceContext) {
+ stuckVars.clear();
+ }
+
+ @Override
+ public void visitLambda(JCLambda tree) {
+ if (inferenceContext.inferenceVars().contains(pt)) {
+ stuckVars.add(pt);
+ }
+ if (!types.isFunctionalInterface(pt)) {
+ return;
+ }
+ Type descType = types.findDescriptorType(pt);
+ List<Type> freeArgVars = inferenceContext.freeVarsIn(descType.getParameterTypes());
+ if (tree.paramKind == JCLambda.ParameterKind.IMPLICIT &&
+ freeArgVars.nonEmpty()) {
+ stuckVars.addAll(freeArgVars);
+ depVars.addAll(inferenceContext.freeVarsIn(descType.getReturnType()));
+ }
+ scanLambdaBody(tree, descType.getReturnType());
+ }
+
+ @Override
+ public void visitReference(JCMemberReference tree) {
+ scan(tree.expr);
+ if (inferenceContext.inferenceVars().contains(pt)) {
+ stuckVars.add(pt);
+ return;
+ }
+ if (!types.isFunctionalInterface(pt)) {
+ return;
+ }
+
+ Type descType = types.findDescriptorType(pt);
+ List<Type> freeArgVars = inferenceContext.freeVarsIn(descType.getParameterTypes());
+ if (freeArgVars.nonEmpty() &&
+ tree.getOverloadKind() == JCMemberReference.OverloadKind.OVERLOADED) {
+ stuckVars.addAll(freeArgVars);
+ depVars.addAll(inferenceContext.freeVarsIn(descType.getReturnType()));
+ }
+ }
+
+ void scanLambdaBody(JCLambda lambda, final Type pt) {
+ if (lambda.getBodyKind() == JCTree.JCLambda.BodyKind.EXPRESSION) {
+ Type prevPt = this.pt;
+ try {
+ this.pt = pt;
+ scan(lambda.body);
+ } finally {
+ this.pt = prevPt;
+ }
+ } else {
+ LambdaReturnScanner lambdaScanner = new LambdaReturnScanner() {
+ @Override
+ public void visitReturn(JCReturn tree) {
+ if (tree.expr != null) {
+ Type prevPt = CheckStuckPolicy.this.pt;
+ try {
+ CheckStuckPolicy.this.pt = pt;
+ CheckStuckPolicy.this.scan(tree.expr);
+ } finally {
+ CheckStuckPolicy.this.pt = prevPt;
+ }
+ }
+ }
+ };
+ lambdaScanner.scan(lambda.body);
+ }
+ }
+ }
+
+ /**
+ * This visitor is used to check that structural expressions conform
+ * to their target - this step is required as inference could end up
+ * inferring types that make some of the nested expressions incompatible
+ * with their corresponding instantiated target
+ */
+ class OverloadStuckPolicy extends CheckStuckPolicy implements DeferredStuckPolicy {
+
+ boolean stuck;
+
+ @Override
+ public boolean isStuck() {
+ return super.isStuck() || stuck;
+ }
+
+ public OverloadStuckPolicy(ResultInfo resultInfo, DeferredType dt) {
+ super(resultInfo, dt);
+ }
+
+ @Override
+ public void visitLambda(JCLambda tree) {
+ super.visitLambda(tree);
+ if (tree.paramKind == JCLambda.ParameterKind.IMPLICIT) {
+ stuck = true;
+ }
+ }
+
+ @Override
+ public void visitReference(JCMemberReference tree) {
+ super.visitReference(tree);
+ if (tree.getOverloadKind() == JCMemberReference.OverloadKind.OVERLOADED) {
+ stuck = true;
+ }
+ }
+ }
+}