1 /*
2 * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 //todo: one might eliminate uninits.andSets when monotonic
27
28 package com.sun.tools.javac.comp;
29
30 import java.util.LinkedHashSet;
31 import java.util.Map;
32 import java.util.Map.Entry;
33 import java.util.HashMap;
34 import java.util.HashSet;
35 import java.util.Set;
36 import java.util.function.Consumer;
37
38 import com.sun.source.tree.LambdaExpressionTree.BodyKind;
39 import com.sun.tools.javac.code.*;
40 import com.sun.tools.javac.code.Scope.WriteableScope;
41 import com.sun.tools.javac.resources.CompilerProperties.Errors;
42 import com.sun.tools.javac.resources.CompilerProperties.LintWarnings;
43 import com.sun.tools.javac.resources.CompilerProperties.Warnings;
44 import com.sun.tools.javac.tree.*;
45 import com.sun.tools.javac.util.*;
46 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
47 import com.sun.tools.javac.util.JCDiagnostic.Error;
48 import com.sun.tools.javac.util.JCDiagnostic.Warning;
49
50 import com.sun.tools.javac.code.Symbol.*;
51 import com.sun.tools.javac.tree.JCTree.*;
52
53 import static com.sun.tools.javac.code.Flags.*;
54 import static com.sun.tools.javac.code.Flags.BLOCK;
55 import com.sun.tools.javac.code.Kinds.Kind;
56 import static com.sun.tools.javac.code.Kinds.Kind.*;
57 import com.sun.tools.javac.code.Type.TypeVar;
58 import static com.sun.tools.javac.code.TypeTag.BOOLEAN;
59 import static com.sun.tools.javac.code.TypeTag.VOID;
60 import com.sun.tools.javac.resources.CompilerProperties.Fragments;
61 import static com.sun.tools.javac.tree.JCTree.Tag.*;
62 import com.sun.tools.javac.util.JCDiagnostic.Fragment;
63 import java.util.Arrays;
64 import java.util.Iterator;
65 import java.util.function.Predicate;
66 import java.util.stream.Collectors;
67
68 import static java.util.stream.Collectors.groupingBy;
69
70 /** This pass implements dataflow analysis for Java programs though
71 * different AST visitor steps. Liveness analysis (see AliveAnalyzer) checks that
72 * every statement is reachable. Exception analysis (see FlowAnalyzer) ensures that
73 * every checked exception that is thrown is declared or caught. Definite assignment analysis
74 * (see AssignAnalyzer) ensures that each variable is assigned when used. Definite
75 * unassignment analysis (see AssignAnalyzer) in ensures that no final variable
76 * is assigned more than once. Finally, local variable capture analysis (see CaptureAnalyzer)
77 * determines that local variables accessed within the scope of an inner class/lambda
78 * are either final or effectively-final.
79 *
80 * <p>The JLS has a number of problems in the
81 * specification of these flow analysis problems. This implementation
82 * attempts to address those issues.
83 *
84 * <p>First, there is no accommodation for a finally clause that cannot
85 * complete normally. For liveness analysis, an intervening finally
86 * clause can cause a break, continue, or return not to reach its
87 * target. For exception analysis, an intervening finally clause can
88 * cause any exception to be "caught". For DA/DU analysis, the finally
89 * clause can prevent a transfer of control from propagating DA/DU
90 * state to the target. In addition, code in the finally clause can
91 * affect the DA/DU status of variables.
92 *
93 * <p>For try statements, we introduce the idea of a variable being
94 * definitely unassigned "everywhere" in a block. A variable V is
95 * "unassigned everywhere" in a block iff it is unassigned at the
96 * beginning of the block and there is no reachable assignment to V
97 * in the block. An assignment V=e is reachable iff V is not DA
98 * after e. Then we can say that V is DU at the beginning of the
99 * catch block iff V is DU everywhere in the try block. Similarly, V
100 * is DU at the beginning of the finally block iff V is DU everywhere
101 * in the try block and in every catch block. Specifically, the
102 * following bullet is added to 16.2.2
103 * <pre>
104 * V is <em>unassigned everywhere</em> in a block if it is
105 * unassigned before the block and there is no reachable
106 * assignment to V within the block.
107 * </pre>
108 * <p>In 16.2.15, the third bullet (and all of its sub-bullets) for all
109 * try blocks is changed to
110 * <pre>
111 * V is definitely unassigned before a catch block iff V is
112 * definitely unassigned everywhere in the try block.
113 * </pre>
114 * <p>The last bullet (and all of its sub-bullets) for try blocks that
115 * have a finally block is changed to
116 * <pre>
117 * V is definitely unassigned before the finally block iff
118 * V is definitely unassigned everywhere in the try block
119 * and everywhere in each catch block of the try statement.
120 * </pre>
121 * <p>In addition,
122 * <pre>
123 * V is definitely assigned at the end of a constructor iff
124 * V is definitely assigned after the block that is the body
125 * of the constructor and V is definitely assigned at every
126 * return that can return from the constructor.
127 * </pre>
128 * <p>In addition, each continue statement with the loop as its target
129 * is treated as a jump to the end of the loop body, and "intervening"
130 * finally clauses are treated as follows: V is DA "due to the
131 * continue" iff V is DA before the continue statement or V is DA at
132 * the end of any intervening finally block. V is DU "due to the
133 * continue" iff any intervening finally cannot complete normally or V
134 * is DU at the end of every intervening finally block. This "due to
135 * the continue" concept is then used in the spec for the loops.
136 *
137 * <p>Similarly, break statements must consider intervening finally
138 * blocks. For liveness analysis, a break statement for which any
139 * intervening finally cannot complete normally is not considered to
140 * cause the target statement to be able to complete normally. Then
141 * we say V is DA "due to the break" iff V is DA before the break or
142 * V is DA at the end of any intervening finally block. V is DU "due
143 * to the break" iff any intervening finally cannot complete normally
144 * or V is DU at the break and at the end of every intervening
145 * finally block. (I suspect this latter condition can be
146 * simplified.) This "due to the break" is then used in the spec for
147 * all statements that can be "broken".
148 *
149 * <p>The return statement is treated similarly. V is DA "due to a
150 * return statement" iff V is DA before the return statement or V is
151 * DA at the end of any intervening finally block. Note that we
152 * don't have to worry about the return expression because this
153 * concept is only used for constructors.
154 *
155 * <p>There is no spec in the JLS for when a variable is definitely
156 * assigned at the end of a constructor, which is needed for final
157 * fields (8.3.1.2). We implement the rule that V is DA at the end
158 * of the constructor iff it is DA and the end of the body of the
159 * constructor and V is DA "due to" every return of the constructor.
160 *
161 * <p>Intervening finally blocks similarly affect exception analysis. An
162 * intervening finally that cannot complete normally allows us to ignore
163 * an otherwise uncaught exception.
164 *
165 * <p>To implement the semantics of intervening finally clauses, all
166 * nonlocal transfers (break, continue, return, throw, method call that
167 * can throw a checked exception, and a constructor invocation that can
168 * thrown a checked exception) are recorded in a queue, and removed
169 * from the queue when we complete processing the target of the
170 * nonlocal transfer. This allows us to modify the queue in accordance
171 * with the above rules when we encounter a finally clause. The only
172 * exception to this [no pun intended] is that checked exceptions that
173 * are known to be caught or declared to be caught in the enclosing
174 * method are not recorded in the queue, but instead are recorded in a
175 * global variable "{@code Set<Type> thrown}" that records the type of all
176 * exceptions that can be thrown.
177 *
178 * <p>Other minor issues the treatment of members of other classes
179 * (always considered DA except that within an anonymous class
180 * constructor, where DA status from the enclosing scope is
181 * preserved), treatment of the case expression (V is DA before the
182 * case expression iff V is DA after the switch expression),
183 * treatment of variables declared in a switch block (the implied
184 * DA/DU status after the switch expression is DU and not DA for
185 * variables defined in a switch block), the treatment of boolean ?:
186 * expressions (The JLS rules only handle b and c non-boolean; the
187 * new rule is that if b and c are boolean valued, then V is
188 * (un)assigned after a?b:c when true/false iff V is (un)assigned
189 * after b when true/false and V is (un)assigned after c when
190 * true/false).
191 *
192 * <p>There is the remaining question of what syntactic forms constitute a
193 * reference to a variable. It is conventional to allow this.x on the
194 * left-hand-side to initialize a final instance field named x, yet
195 * this.x isn't considered a "use" when appearing on a right-hand-side
196 * in most implementations. Should parentheses affect what is
197 * considered a variable reference? The simplest rule would be to
198 * allow unqualified forms only, parentheses optional, and phase out
199 * support for assigning to a final field via this.x.
200 *
201 * <p><b>This is NOT part of any supported API.
202 * If you write code that depends on this, you do so at your own risk.
203 * This code and its internal interfaces are subject to change or
204 * deletion without notice.</b>
205 */
206 public class Flow {
207 protected static final Context.Key<Flow> flowKey = new Context.Key<>();
208
209 private final Names names;
210 private final Log log;
211 private final Symtab syms;
212 private final Types types;
213 private final Check chk;
214 private TreeMaker make;
215 private final Resolve rs;
216 private final JCDiagnostic.Factory diags;
217 private Env<AttrContext> attrEnv;
218 private Lint lint;
219 private final Infer infer;
220 private final UnsetFieldsInfo unsetFieldsInfo;
221
222 public static Flow instance(Context context) {
223 Flow instance = context.get(flowKey);
224 if (instance == null)
225 instance = new Flow(context);
226 return instance;
227 }
228
229 public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
230 new AliveAnalyzer().analyzeTree(env, make);
231 new AssignAnalyzer().analyzeTree(env, make);
232 new FlowAnalyzer().analyzeTree(env, make);
233 new CaptureAnalyzer().analyzeTree(env, make);
234 }
235
236 public void analyzeLambda(Env<AttrContext> env, JCLambda that, TreeMaker make, boolean speculative) {
237 Log.DiagnosticHandler diagHandler = null;
238 //we need to disable diagnostics temporarily; the problem is that if
239 //a lambda expression contains e.g. an unreachable statement, an error
240 //message will be reported and will cause compilation to skip the flow analysis
241 //step - if we suppress diagnostics, we won't stop at Attr for flow-analysis
242 //related errors, which will allow for more errors to be detected
243 if (!speculative) {
244 diagHandler = new Log.DiscardDiagnosticHandler(log);
245 }
246 try {
247 new LambdaAliveAnalyzer().analyzeTree(env, that, make);
248 } finally {
249 if (!speculative) {
250 log.popDiagnosticHandler(diagHandler);
251 }
252 }
253 }
254
255 public List<Type> analyzeLambdaThrownTypes(final Env<AttrContext> env,
256 JCLambda that, TreeMaker make) {
257 //we need to disable diagnostics temporarily; the problem is that if
258 //a lambda expression contains e.g. an unreachable statement, an error
259 //message will be reported and will cause compilation to skip the flow analysis
260 //step - if we suppress diagnostics, we won't stop at Attr for flow-analysis
261 //related errors, which will allow for more errors to be detected
262 Log.DiagnosticHandler diagHandler = new Log.DiscardDiagnosticHandler(log);
263 try {
264 new LambdaAssignAnalyzer(env).analyzeTree(env, that, make);
265 LambdaFlowAnalyzer flowAnalyzer = new LambdaFlowAnalyzer();
266 flowAnalyzer.analyzeTree(env, that, make);
267 return flowAnalyzer.inferredThrownTypes;
268 } finally {
269 log.popDiagnosticHandler(diagHandler);
270 }
271 }
272
273 public boolean aliveAfter(Env<AttrContext> env, JCTree that, TreeMaker make) {
274 //we need to disable diagnostics temporarily; the problem is that if
275 //"that" contains e.g. an unreachable statement, an error
276 //message will be reported and will cause compilation to skip the flow analysis
277 //step - if we suppress diagnostics, we won't stop at Attr for flow-analysis
278 //related errors, which will allow for more errors to be detected
279 Log.DiagnosticHandler diagHandler = new Log.DiscardDiagnosticHandler(log);
280 try {
281 SnippetAliveAnalyzer analyzer = new SnippetAliveAnalyzer();
282
283 analyzer.analyzeTree(env, that, make);
284 return analyzer.isAlive();
285 } finally {
286 log.popDiagnosticHandler(diagHandler);
287 }
288 }
289
290 public boolean breaksToTree(Env<AttrContext> env, JCTree breakTo, JCTree body, TreeMaker make) {
291 //we need to disable diagnostics temporarily; the problem is that if
292 //"that" contains e.g. an unreachable statement, an error
293 //message will be reported and will cause compilation to skip the flow analysis
294 //step - if we suppress diagnostics, we won't stop at Attr for flow-analysis
295 //related errors, which will allow for more errors to be detected
296 Log.DiagnosticHandler diagHandler = new Log.DiscardDiagnosticHandler(log);
297 try {
298 SnippetBreakToAnalyzer analyzer = new SnippetBreakToAnalyzer(breakTo);
299
300 analyzer.analyzeTree(env, body, make);
301 return analyzer.breaksTo();
302 } finally {
303 log.popDiagnosticHandler(diagHandler);
304 }
305 }
306
307 /**
308 * Definite assignment scan mode
309 */
310 enum FlowKind {
311 /**
312 * This is the normal DA/DU analysis mode
313 */
314 NORMAL("var.might.already.be.assigned", false),
315 /**
316 * This is the speculative DA/DU analysis mode used to speculatively
317 * derive assertions within loop bodies
318 */
319 SPECULATIVE_LOOP("var.might.be.assigned.in.loop", true);
320
321 final String errKey;
322 final boolean isFinal;
323
324 FlowKind(String errKey, boolean isFinal) {
325 this.errKey = errKey;
326 this.isFinal = isFinal;
327 }
328
329 boolean isFinal() {
330 return isFinal;
331 }
332 }
333
334 @SuppressWarnings("this-escape")
335 protected Flow(Context context) {
336 context.put(flowKey, this);
337 names = Names.instance(context);
338 log = Log.instance(context);
339 syms = Symtab.instance(context);
340 types = Types.instance(context);
341 chk = Check.instance(context);
342 lint = Lint.instance(context);
343 infer = Infer.instance(context);
344 rs = Resolve.instance(context);
345 diags = JCDiagnostic.Factory.instance(context);
346 unsetFieldsInfo = UnsetFieldsInfo.instance(context);
347 }
348
349 /**
350 * Base visitor class for all visitors implementing dataflow analysis logic.
351 * This class define the shared logic for handling jumps (break/continue statements).
352 */
353 abstract static class BaseAnalyzer extends TreeScanner {
354
355 enum JumpKind {
356 BREAK(JCTree.Tag.BREAK) {
357 @Override
358 JCTree getTarget(JCTree tree) {
359 return ((JCBreak)tree).target;
360 }
361 },
362 CONTINUE(JCTree.Tag.CONTINUE) {
363 @Override
364 JCTree getTarget(JCTree tree) {
365 return ((JCContinue)tree).target;
366 }
367 },
368 YIELD(JCTree.Tag.YIELD) {
369 @Override
370 JCTree getTarget(JCTree tree) {
371 return ((JCYield)tree).target;
372 }
373 };
374
375 final JCTree.Tag treeTag;
376
377 private JumpKind(Tag treeTag) {
378 this.treeTag = treeTag;
379 }
380
381 abstract JCTree getTarget(JCTree tree);
382 }
383
384 /** The currently pending exits that go from current inner blocks
385 * to an enclosing block, in source order.
386 */
387 ListBuffer<PendingExit> pendingExits;
388
389 /** A class whose initializers we are scanning. Because initializer
390 * scans can be triggered out of sequence when visiting certain nodes
391 * (e.g., super()), we protect against infinite loops that could be
392 * triggered by incorrect code (e.g., super() inside initializer).
393 */
394 JCClassDecl initScanClass;
395
396 /** A pending exit. These are the statements return, break, and
397 * continue. In addition, exception-throwing expressions or
398 * statements are put here when not known to be caught. This
399 * will typically result in an error unless it is within a
400 * try-finally whose finally block cannot complete normally.
401 */
402 static class PendingExit {
403 JCTree tree;
404
405 PendingExit(JCTree tree) {
406 this.tree = tree;
407 }
408
409 void resolveJump() {
410 //do nothing
411 }
412 }
413
414 abstract void markDead();
415
416 /** Record an outward transfer of control. */
417 void recordExit(PendingExit pe) {
418 pendingExits.append(pe);
419 markDead();
420 }
421
422 /** Resolve all jumps of this statement. */
423 private Liveness resolveJump(JCTree tree,
424 ListBuffer<PendingExit> oldPendingExits,
425 JumpKind jk) {
426 boolean resolved = false;
427 List<PendingExit> exits = pendingExits.toList();
428 pendingExits = oldPendingExits;
429 for (; exits.nonEmpty(); exits = exits.tail) {
430 PendingExit exit = exits.head;
431 if (exit.tree.hasTag(jk.treeTag) &&
432 jk.getTarget(exit.tree) == tree) {
433 exit.resolveJump();
434 resolved = true;
435 } else {
436 pendingExits.append(exit);
437 }
438 }
439 return Liveness.from(resolved);
440 }
441
442 /** Resolve all continues of this statement. */
443 Liveness resolveContinues(JCTree tree) {
444 return resolveJump(tree, new ListBuffer<PendingExit>(), JumpKind.CONTINUE);
445 }
446
447 /** Resolve all breaks of this statement. */
448 Liveness resolveBreaks(JCTree tree, ListBuffer<PendingExit> oldPendingExits) {
449 return resolveJump(tree, oldPendingExits, JumpKind.BREAK);
450 }
451
452 /** Resolve all yields of this statement. */
453 Liveness resolveYields(JCTree tree, ListBuffer<PendingExit> oldPendingExits) {
454 return resolveJump(tree, oldPendingExits, JumpKind.YIELD);
455 }
456
457 @Override
458 public void scan(JCTree tree) {
459 if (tree != null && (
460 tree.type == null ||
461 tree.type != Type.stuckType)) {
462 super.scan(tree);
463 }
464 }
465
466 public void visitPackageDef(JCPackageDecl tree) {
467 // Do nothing for PackageDecl
468 }
469
470 protected void scanSyntheticBreak(TreeMaker make, JCTree swtch) {
471 if (swtch.hasTag(SWITCH_EXPRESSION)) {
472 JCYield brk = make.at(Position.NOPOS).Yield(make.Erroneous()
473 .setType(swtch.type));
474 brk.target = swtch;
475 scan(brk);
476 } else {
477 JCBreak brk = make.at(Position.NOPOS).Break(null);
478 brk.target = swtch;
479 scan(brk);
480 }
481 }
482
483 // Do something with static or non-static field initializers and initialization blocks.
484 protected void forEachInitializer(JCClassDecl classDef, boolean isStatic, Consumer<? super JCTree> handler) {
485 forEachInitializer(classDef, isStatic, false, handler);
486 }
487
488 /* Do something with static or non-static field initializers and initialization blocks.
489 * the `earlyOnly` argument will determine if we will deal or not with early variable instance
490 * initializers we want to process only those before a super() invocation and ignore them after
491 * it.
492 */
493 protected void forEachInitializer(JCClassDecl classDef, boolean isStatic, boolean earlyOnly,
494 Consumer<? super JCTree> handler) {
495 if (classDef == initScanClass) // avoid infinite loops
496 return;
497 JCClassDecl initScanClassPrev = initScanClass;
498 initScanClass = classDef;
499 try {
500 for (List<JCTree> defs = classDef.defs; defs.nonEmpty(); defs = defs.tail) {
501 JCTree def = defs.head;
502
503 // Don't recurse into nested classes
504 if (def.hasTag(CLASSDEF))
505 continue;
506
507 /* we need to check for flags in the symbol too as there could be cases for which implicit flags are
508 * represented in the symbol but not in the tree modifiers as they were not originally in the source
509 * code
510 */
511 boolean isDefStatic = ((TreeInfo.flags(def) | (TreeInfo.symbolFor(def) == null ? 0 : TreeInfo.symbolFor(def).flags_field)) & STATIC) != 0;
512 if (!def.hasTag(METHODDEF) && (isDefStatic == isStatic)) {
513 if (def instanceof JCVariableDecl varDecl) {
514 boolean isEarly = varDecl.init != null &&
515 varDecl.sym.isStrict() &&
516 !varDecl.sym.isStatic();
517 if (isEarly == earlyOnly) {
518 handler.accept(def);
519 }
520 } else if (!earlyOnly) {
521 handler.accept(def);
522 }
523 }
524 }
525 } finally {
526 initScanClass = initScanClassPrev;
527 }
528 }
529 }
530
531 /**
532 * This pass implements the first step of the dataflow analysis, namely
533 * the liveness analysis check. This checks that every statement is reachable.
534 * The output of this analysis pass are used by other analyzers. This analyzer
535 * sets the 'finallyCanCompleteNormally' field in the JCTry class.
536 */
537 class AliveAnalyzer extends BaseAnalyzer {
538
539 /** A flag that indicates whether the last statement could
540 * complete normally.
541 */
542 private Liveness alive;
543
544 @Override
545 void markDead() {
546 alive = Liveness.DEAD;
547 }
548
549 /* ***********************************************************************
550 * Visitor methods for statements and definitions
551 *************************************************************************/
552
553 /** Analyze a definition.
554 */
555 void scanDef(JCTree tree) {
556 scanStat(tree);
557 if (tree != null && tree.hasTag(JCTree.Tag.BLOCK) && alive == Liveness.DEAD) {
558 log.error(tree.pos(),
559 Errors.InitializerMustBeAbleToCompleteNormally);
560 }
561 }
562
563 /** Analyze a statement. Check that statement is reachable.
564 */
565 void scanStat(JCTree tree) {
566 if (alive == Liveness.DEAD && tree != null) {
567 log.error(tree.pos(), Errors.UnreachableStmt);
568 if (!tree.hasTag(SKIP)) alive = Liveness.RECOVERY;
569 }
570 scan(tree);
571 }
572
573 /** Analyze list of statements.
574 */
575 void scanStats(List<? extends JCStatement> trees) {
576 if (trees != null)
577 for (List<? extends JCStatement> l = trees; l.nonEmpty(); l = l.tail)
578 scanStat(l.head);
579 }
580
581 /* ------------ Visitor methods for various sorts of trees -------------*/
582
583 public void visitClassDef(JCClassDecl tree) {
584 if (tree.sym == null) return;
585 Liveness alivePrev = alive;
586 ListBuffer<PendingExit> pendingExitsPrev = pendingExits;
587 Lint lintPrev = lint;
588
589 pendingExits = new ListBuffer<>();
590 lint = lint.augment(tree.sym);
591
592 try {
593 // process all the nested classes
594 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
595 if (l.head.hasTag(CLASSDEF)) {
596 scan(l.head);
597 }
598 }
599
600 // process all the static initializers
601 forEachInitializer(tree, true, def -> {
602 scanDef(def);
603 clearPendingExits(false);
604 });
605
606 // process all the instance initializers
607 forEachInitializer(tree, false, def -> {
608 scanDef(def);
609 clearPendingExits(false);
610 });
611
612 // process all the methods
613 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
614 if (l.head.hasTag(METHODDEF)) {
615 scan(l.head);
616 }
617 }
618 } finally {
619 pendingExits = pendingExitsPrev;
620 alive = alivePrev;
621 lint = lintPrev;
622 }
623 }
624
625 public void visitMethodDef(JCMethodDecl tree) {
626 if (tree.body == null) return;
627 Lint lintPrev = lint;
628
629 lint = lint.augment(tree.sym);
630
631 Assert.check(pendingExits.isEmpty());
632
633 try {
634 alive = Liveness.ALIVE;
635 scanStat(tree.body);
636 tree.completesNormally = alive != Liveness.DEAD;
637
638 if (alive == Liveness.ALIVE && !tree.sym.type.getReturnType().hasTag(VOID))
639 log.error(TreeInfo.diagEndPos(tree.body), Errors.MissingRetStmt);
640
641 clearPendingExits(true);
642 } finally {
643 lint = lintPrev;
644 }
645 }
646
647 private void clearPendingExits(boolean inMethod) {
648 List<PendingExit> exits = pendingExits.toList();
649 pendingExits = new ListBuffer<>();
650 while (exits.nonEmpty()) {
651 PendingExit exit = exits.head;
652 exits = exits.tail;
653 Assert.check((inMethod && exit.tree.hasTag(RETURN)) ||
654 log.hasErrorOn(exit.tree.pos()));
655 }
656 }
657
658 public void visitVarDef(JCVariableDecl tree) {
659 if (tree.init != null) {
660 Lint lintPrev = lint;
661 lint = lint.augment(tree.sym);
662 try{
663 scan(tree.init);
664 } finally {
665 lint = lintPrev;
666 }
667 }
668 }
669
670 public void visitBlock(JCBlock tree) {
671 scanStats(tree.stats);
672 }
673
674 public void visitDoLoop(JCDoWhileLoop tree) {
675 ListBuffer<PendingExit> prevPendingExits = pendingExits;
676 pendingExits = new ListBuffer<>();
677 scanStat(tree.body);
678 alive = alive.or(resolveContinues(tree));
679 scan(tree.cond);
680 alive = alive.and(!tree.cond.type.isTrue());
681 alive = alive.or(resolveBreaks(tree, prevPendingExits));
682 }
683
684 public void visitWhileLoop(JCWhileLoop tree) {
685 ListBuffer<PendingExit> prevPendingExits = pendingExits;
686 pendingExits = new ListBuffer<>();
687 scan(tree.cond);
688 alive = Liveness.from(!tree.cond.type.isFalse());
689 scanStat(tree.body);
690 alive = alive.or(resolveContinues(tree));
691 alive = resolveBreaks(tree, prevPendingExits).or(
692 !tree.cond.type.isTrue());
693 }
694
695 public void visitForLoop(JCForLoop tree) {
696 ListBuffer<PendingExit> prevPendingExits = pendingExits;
697 scanStats(tree.init);
698 pendingExits = new ListBuffer<>();
699 if (tree.cond != null) {
700 scan(tree.cond);
701 alive = Liveness.from(!tree.cond.type.isFalse());
702 } else {
703 alive = Liveness.ALIVE;
704 }
705 scanStat(tree.body);
706 alive = alive.or(resolveContinues(tree));
707 scan(tree.step);
708 alive = resolveBreaks(tree, prevPendingExits).or(
709 tree.cond != null && !tree.cond.type.isTrue());
710 }
711
712 public void visitForeachLoop(JCEnhancedForLoop tree) {
713 visitVarDef(tree.var);
714 ListBuffer<PendingExit> prevPendingExits = pendingExits;
715 scan(tree.expr);
716 pendingExits = new ListBuffer<>();
717 scanStat(tree.body);
718 alive = alive.or(resolveContinues(tree));
719 resolveBreaks(tree, prevPendingExits);
720 alive = Liveness.ALIVE;
721 }
722
723 public void visitLabelled(JCLabeledStatement tree) {
724 ListBuffer<PendingExit> prevPendingExits = pendingExits;
725 pendingExits = new ListBuffer<>();
726 scanStat(tree.body);
727 alive = alive.or(resolveBreaks(tree, prevPendingExits));
728 }
729
730 public void visitSwitch(JCSwitch tree) {
731 ListBuffer<PendingExit> prevPendingExits = pendingExits;
732 pendingExits = new ListBuffer<>();
733 scan(tree.selector);
734 boolean exhaustiveSwitch = TreeInfo.expectedExhaustive(tree);
735 for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {
736 alive = Liveness.ALIVE;
737 JCCase c = l.head;
738 for (JCCaseLabel pat : c.labels) {
739 scan(pat);
740 }
741 scanStats(c.stats);
742 if (alive != Liveness.DEAD && c.caseKind == JCCase.RULE) {
743 scanSyntheticBreak(make, tree);
744 alive = Liveness.DEAD;
745 }
746 // Warn about fall-through if lint switch fallthrough enabled.
747 if (alive == Liveness.ALIVE &&
748 c.stats.nonEmpty() && l.tail.nonEmpty())
749 lint.logIfEnabled(l.tail.head.pos(),
750 LintWarnings.PossibleFallThroughIntoCase);
751 }
752 tree.isExhaustive = tree.hasUnconditionalPattern ||
753 TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases);
754 if (exhaustiveSwitch) {
755 tree.isExhaustive |= exhausts(tree.selector, tree.cases);
756 if (!tree.isExhaustive) {
757 log.error(tree, Errors.NotExhaustiveStatement);
758 }
759 }
760 if (!tree.hasUnconditionalPattern && !exhaustiveSwitch) {
761 alive = Liveness.ALIVE;
762 }
763 alive = alive.or(resolveBreaks(tree, prevPendingExits));
764 }
765
766 @Override
767 public void visitSwitchExpression(JCSwitchExpression tree) {
768 ListBuffer<PendingExit> prevPendingExits = pendingExits;
769 pendingExits = new ListBuffer<>();
770 scan(tree.selector);
771 Liveness prevAlive = alive;
772 for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {
773 alive = Liveness.ALIVE;
774 JCCase c = l.head;
775 for (JCCaseLabel pat : c.labels) {
776 scan(pat);
777 }
778 scanStats(c.stats);
779 if (alive == Liveness.ALIVE) {
780 if (c.caseKind == JCCase.RULE) {
781 log.error(TreeInfo.diagEndPos(c.body),
782 Errors.RuleCompletesNormally);
783 } else if (l.tail.isEmpty()) {
784 log.error(TreeInfo.diagEndPos(tree),
785 Errors.SwitchExpressionCompletesNormally);
786 }
787 }
788 }
789
790 if (tree.hasUnconditionalPattern ||
791 TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases)) {
792 tree.isExhaustive = true;
793 } else {
794 tree.isExhaustive = exhausts(tree.selector, tree.cases);
795 }
796
797 if (!tree.isExhaustive) {
798 log.error(tree, Errors.NotExhaustive);
799 }
800 alive = prevAlive;
801 alive = alive.or(resolveYields(tree, prevPendingExits));
802 }
803
804 private boolean exhausts(JCExpression selector, List<JCCase> cases) {
805 Set<PatternDescription> patternSet = new HashSet<>();
806 Map<Symbol, Set<Symbol>> enum2Constants = new HashMap<>();
807 Set<Object> booleanLiterals = new HashSet<>(Set.of(0, 1));
808 for (JCCase c : cases) {
809 if (!TreeInfo.unguardedCase(c))
810 continue;
811
812 for (var l : c.labels) {
813 if (l instanceof JCPatternCaseLabel patternLabel) {
814 for (Type component : components(selector.type)) {
815 patternSet.add(makePatternDescription(component, patternLabel.pat));
816 }
817 } else if (l instanceof JCConstantCaseLabel constantLabel) {
818 if (types.unboxedTypeOrType(selector.type).hasTag(TypeTag.BOOLEAN)) {
819 Object value = ((JCLiteral) constantLabel.expr).value;
820 booleanLiterals.remove(value);
821 } else {
822 Symbol s = TreeInfo.symbol(constantLabel.expr);
823 if (s != null && s.isEnum()) {
824 enum2Constants.computeIfAbsent(s.owner, x -> {
825 Set<Symbol> result = new HashSet<>();
826 s.owner.members()
827 .getSymbols(sym -> sym.kind == Kind.VAR && sym.isEnum())
828 .forEach(result::add);
829 return result;
830 }).remove(s);
831 }
832 }
833 }
834 }
835 }
836
837 if (types.unboxedTypeOrType(selector.type).hasTag(TypeTag.BOOLEAN) && booleanLiterals.isEmpty()) {
838 return true;
839 }
840
841 for (Entry<Symbol, Set<Symbol>> e : enum2Constants.entrySet()) {
842 if (e.getValue().isEmpty()) {
843 patternSet.add(new BindingPattern(e.getKey().type));
844 }
845 }
846 Set<PatternDescription> patterns = patternSet;
847 boolean useHashes = true;
848 try {
849 boolean repeat = true;
850 while (repeat) {
851 Set<PatternDescription> updatedPatterns;
852 updatedPatterns = reduceBindingPatterns(selector.type, patterns);
853 updatedPatterns = reduceNestedPatterns(updatedPatterns, useHashes);
854 updatedPatterns = reduceRecordPatterns(updatedPatterns);
855 updatedPatterns = removeCoveredRecordPatterns(updatedPatterns);
856 repeat = !updatedPatterns.equals(patterns);
857 if (checkCovered(selector.type, patterns)) {
858 return true;
859 }
860 if (!repeat) {
861 //there may be situation like:
862 //class B permits S1, S2
863 //patterns: R(S1, B), R(S2, S2)
864 //this might be joined to R(B, S2), as B could be rewritten to S2
865 //but hashing in reduceNestedPatterns will not allow that
866 //disable the use of hashing, and use subtyping in
867 //reduceNestedPatterns to handle situations like this:
868 repeat = useHashes;
869 useHashes = false;
870 } else {
871 //if a reduction happened, make sure hashing in reduceNestedPatterns
872 //is enabled, as the hashing speeds up the process significantly:
873 useHashes = true;
874 }
875 patterns = updatedPatterns;
876 }
877 return checkCovered(selector.type, patterns);
878 } catch (CompletionFailure cf) {
879 chk.completionError(selector.pos(), cf);
880 return true; //error recovery
881 }
882 }
883
884 private boolean checkCovered(Type seltype, Iterable<PatternDescription> patterns) {
885 for (Type seltypeComponent : components(seltype)) {
886 for (PatternDescription pd : patterns) {
887 if(isBpCovered(seltypeComponent, pd)) {
888 return true;
889 }
890 }
891 }
892 return false;
893 }
894
895 private List<Type> components(Type seltype) {
896 return switch (seltype.getTag()) {
897 case CLASS -> {
898 if (seltype.isCompound()) {
899 if (seltype.isIntersection()) {
900 yield ((Type.IntersectionClassType) seltype).getComponents()
901 .stream()
902 .flatMap(t -> components(t).stream())
903 .collect(List.collector());
904 }
905 yield List.nil();
906 }
907 yield List.of(types.erasure(seltype));
908 }
909 case TYPEVAR -> components(((TypeVar) seltype).getUpperBound());
910 default -> List.of(types.erasure(seltype));
911 };
912 }
913
914 /* In a set of patterns, search for a sub-set of binding patterns that
915 * in combination exhaust their sealed supertype. If such a sub-set
916 * is found, it is removed, and replaced with a binding pattern
917 * for the sealed supertype.
918 */
919 private Set<PatternDescription> reduceBindingPatterns(Type selectorType, Set<PatternDescription> patterns) {
920 Set<Symbol> existingBindings = patterns.stream()
921 .filter(pd -> pd instanceof BindingPattern)
922 .map(pd -> ((BindingPattern) pd).type.tsym)
923 .collect(Collectors.toSet());
924
925 for (PatternDescription pdOne : patterns) {
926 if (pdOne instanceof BindingPattern bpOne) {
927 Set<PatternDescription> toAdd = new HashSet<>();
928
929 for (Type sup : types.directSupertypes(bpOne.type)) {
930 ClassSymbol clazz = (ClassSymbol) types.erasure(sup).tsym;
931
932 clazz.complete();
933
934 if (clazz.isSealed() && clazz.isAbstract() &&
935 //if a binding pattern for clazz already exists, no need to analyze it again:
936 !existingBindings.contains(clazz)) {
937 ListBuffer<PatternDescription> bindings = new ListBuffer<>();
938 //do not reduce to types unrelated to the selector type:
939 Type clazzErasure = types.erasure(clazz.type);
940 if (components(selectorType).stream()
941 .map(types::erasure)
942 .noneMatch(c -> types.isSubtype(clazzErasure, c))) {
943 continue;
944 }
945
946 Set<Symbol> permitted = allPermittedSubTypes(clazz, csym -> {
947 Type instantiated;
948 if (csym.type.allparams().isEmpty()) {
949 instantiated = csym.type;
950 } else {
951 instantiated = infer.instantiatePatternType(selectorType, csym);
952 }
953
954 return instantiated != null && types.isCastable(selectorType, instantiated);
955 });
956
957 for (PatternDescription pdOther : patterns) {
958 if (pdOther instanceof BindingPattern bpOther) {
959 Set<Symbol> currentPermittedSubTypes =
960 allPermittedSubTypes(bpOther.type.tsym, s -> true);
961
962 PERMITTED: for (Iterator<Symbol> it = permitted.iterator(); it.hasNext();) {
963 Symbol perm = it.next();
964
965 for (Symbol currentPermitted : currentPermittedSubTypes) {
966 if (types.isSubtype(types.erasure(currentPermitted.type),
967 types.erasure(perm.type))) {
968 it.remove();
969 continue PERMITTED;
970 }
971 }
972 if (types.isSubtype(types.erasure(perm.type),
973 types.erasure(bpOther.type))) {
974 it.remove();
975 }
976 }
977 }
978 }
979
980 if (permitted.isEmpty()) {
981 toAdd.add(new BindingPattern(clazz.type));
982 }
983 }
984 }
985
986 if (!toAdd.isEmpty()) {
987 Set<PatternDescription> newPatterns = new HashSet<>(patterns);
988 newPatterns.addAll(toAdd);
989 return newPatterns;
990 }
991 }
992 }
993 return patterns;
994 }
995
996 private Set<Symbol> allPermittedSubTypes(TypeSymbol root, Predicate<ClassSymbol> accept) {
997 Set<Symbol> permitted = new HashSet<>();
998 List<ClassSymbol> permittedSubtypesClosure = baseClasses(root);
999
1000 while (permittedSubtypesClosure.nonEmpty()) {
1001 ClassSymbol current = permittedSubtypesClosure.head;
1002
1003 permittedSubtypesClosure = permittedSubtypesClosure.tail;
1004
1005 current.complete();
1006
1007 if (current.isSealed() && current.isAbstract()) {
1008 for (Type t : current.getPermittedSubclasses()) {
1009 ClassSymbol csym = (ClassSymbol) t.tsym;
1010
1011 if (accept.test(csym)) {
1012 permittedSubtypesClosure = permittedSubtypesClosure.prepend(csym);
1013 permitted.add(csym);
1014 }
1015 }
1016 }
1017 }
1018
1019 return permitted;
1020 }
1021
1022 private List<ClassSymbol> baseClasses(TypeSymbol root) {
1023 if (root instanceof ClassSymbol clazz) {
1024 return List.of(clazz);
1025 } else if (root instanceof TypeVariableSymbol tvar) {
1026 ListBuffer<ClassSymbol> result = new ListBuffer<>();
1027 for (Type bound : tvar.getBounds()) {
1028 result.appendList(baseClasses(bound.tsym));
1029 }
1030 return result.toList();
1031 } else {
1032 return List.nil();
1033 }
1034 }
1035
1036 /* Among the set of patterns, find sub-set of patterns such:
1037 * $record($prefix$, $nested, $suffix$)
1038 * Where $record, $prefix$ and $suffix$ is the same for each pattern
1039 * in the set, and the patterns only differ in one "column" in
1040 * the $nested pattern.
1041 * Then, the set of $nested patterns is taken, and passed recursively
1042 * to reduceNestedPatterns and to reduceBindingPatterns, to
1043 * simplify the pattern. If that succeeds, the original found sub-set
1044 * of patterns is replaced with a new set of patterns of the form:
1045 * $record($prefix$, $resultOfReduction, $suffix$)
1046 *
1047 * useHashes: when true, patterns will be subject to exact equivalence;
1048 * when false, two binding patterns will be considered equivalent
1049 * if one of them is more generic than the other one;
1050 * when false, the processing will be significantly slower,
1051 * as pattern hashes cannot be used to speed up the matching process
1052 */
1053 private Set<PatternDescription> reduceNestedPatterns(Set<PatternDescription> patterns,
1054 boolean useHashes) {
1055 /* implementation note:
1056 * finding a sub-set of patterns that only differ in a single
1057 * column is time-consuming task, so this method speeds it up by:
1058 * - group the patterns by their record class
1059 * - for each column (nested pattern) do:
1060 * -- group patterns by their hash
1061 * -- in each such by-hash group, find sub-sets that only differ in
1062 * the chosen column, and then call reduceBindingPatterns and reduceNestedPatterns
1063 * on patterns in the chosen column, as described above
1064 */
1065 var groupByRecordClass =
1066 patterns.stream()
1067 .filter(pd -> pd instanceof RecordPattern)
1068 .map(pd -> (RecordPattern) pd)
1069 .collect(groupingBy(pd -> (ClassSymbol) pd.recordType.tsym));
1070
1071 for (var e : groupByRecordClass.entrySet()) {
1072 int nestedPatternsCount = e.getKey().getRecordComponents().size();
1073 Set<RecordPattern> current = new HashSet<>(e.getValue());
1074
1075 for (int mismatchingCandidate = 0;
1076 mismatchingCandidate < nestedPatternsCount;
1077 mismatchingCandidate++) {
1078 int mismatchingCandidateFin = mismatchingCandidate;
1079 var groupEquivalenceCandidates =
1080 current
1081 .stream()
1082 //error recovery, ignore patterns with incorrect number of nested patterns:
1083 .filter(pd -> pd.nested.length == nestedPatternsCount)
1084 .collect(groupingBy(pd -> useHashes ? pd.hashCode(mismatchingCandidateFin) : 0));
1085 for (var candidates : groupEquivalenceCandidates.values()) {
1086 var candidatesArr = candidates.toArray(RecordPattern[]::new);
1087
1088 for (int firstCandidate = 0;
1089 firstCandidate < candidatesArr.length;
1090 firstCandidate++) {
1091 RecordPattern rpOne = candidatesArr[firstCandidate];
1092 ListBuffer<RecordPattern> join = new ListBuffer<>();
1093
1094 join.append(rpOne);
1095
1096 NEXT_PATTERN: for (int nextCandidate = 0;
1097 nextCandidate < candidatesArr.length;
1098 nextCandidate++) {
1099 if (firstCandidate == nextCandidate) {
1100 continue;
1101 }
1102
1103 RecordPattern rpOther = candidatesArr[nextCandidate];
1104 if (rpOne.recordType.tsym == rpOther.recordType.tsym) {
1105 for (int i = 0; i < rpOne.nested.length; i++) {
1106 if (i != mismatchingCandidate) {
1107 if (!rpOne.nested[i].equals(rpOther.nested[i])) {
1108 if (useHashes ||
1109 //when not using hashes,
1110 //check if rpOne.nested[i] is
1111 //a subtype of rpOther.nested[i]:
1112 !(rpOne.nested[i] instanceof BindingPattern bpOne) ||
1113 !(rpOther.nested[i] instanceof BindingPattern bpOther) ||
1114 !types.isSubtype(types.erasure(bpOne.type), types.erasure(bpOther.type))) {
1115 continue NEXT_PATTERN;
1116 }
1117 }
1118 }
1119 }
1120 join.append(rpOther);
1121 }
1122 }
1123
1124 var nestedPatterns = join.stream().map(rp -> rp.nested[mismatchingCandidateFin]).collect(Collectors.toSet());
1125 var updatedPatterns = reduceNestedPatterns(nestedPatterns, useHashes);
1126
1127 updatedPatterns = reduceRecordPatterns(updatedPatterns);
1128 updatedPatterns = removeCoveredRecordPatterns(updatedPatterns);
1129 updatedPatterns = reduceBindingPatterns(rpOne.fullComponentTypes()[mismatchingCandidateFin], updatedPatterns);
1130
1131 if (!nestedPatterns.equals(updatedPatterns)) {
1132 if (useHashes) {
1133 current.removeAll(join);
1134 }
1135
1136 for (PatternDescription nested : updatedPatterns) {
1137 PatternDescription[] newNested =
1138 Arrays.copyOf(rpOne.nested, rpOne.nested.length);
1139 newNested[mismatchingCandidateFin] = nested;
1140 current.add(new RecordPattern(rpOne.recordType(),
1141 rpOne.fullComponentTypes(),
1142 newNested));
1143 }
1144 }
1145 }
1146 }
1147 }
1148
1149 if (!current.equals(new HashSet<>(e.getValue()))) {
1150 Set<PatternDescription> result = new HashSet<>(patterns);
1151 result.removeAll(e.getValue());
1152 result.addAll(current);
1153 return result;
1154 }
1155 }
1156 return patterns;
1157 }
1158
1159 /* In the set of patterns, find those for which, given:
1160 * $record($nested1, $nested2, ...)
1161 * all the $nestedX pattern cover the given record component,
1162 * and replace those with a simple binding pattern over $record.
1163 */
1164 private Set<PatternDescription> reduceRecordPatterns(Set<PatternDescription> patterns) {
1165 var newPatterns = new HashSet<PatternDescription>();
1166 boolean modified = false;
1167 for (PatternDescription pd : patterns) {
1168 if (pd instanceof RecordPattern rpOne) {
1169 PatternDescription reducedPattern = reduceRecordPattern(rpOne);
1170 if (reducedPattern != rpOne) {
1171 newPatterns.add(reducedPattern);
1172 modified = true;
1173 continue;
1174 }
1175 }
1176 newPatterns.add(pd);
1177 }
1178 return modified ? newPatterns : patterns;
1179 }
1180
1181 private PatternDescription reduceRecordPattern(PatternDescription pattern) {
1182 if (pattern instanceof RecordPattern rpOne) {
1183 Type[] componentType = rpOne.fullComponentTypes();
1184 //error recovery, ignore patterns with incorrect number of nested patterns:
1185 if (componentType.length != rpOne.nested.length) {
1186 return pattern;
1187 }
1188 PatternDescription[] reducedNestedPatterns = null;
1189 boolean covered = true;
1190 for (int i = 0; i < componentType.length; i++) {
1191 PatternDescription newNested = reduceRecordPattern(rpOne.nested[i]);
1192 if (newNested != rpOne.nested[i]) {
1193 if (reducedNestedPatterns == null) {
1194 reducedNestedPatterns = Arrays.copyOf(rpOne.nested, rpOne.nested.length);
1195 }
1196 reducedNestedPatterns[i] = newNested;
1197 }
1198
1199 covered &= checkCovered(componentType[i], List.of(newNested));
1200 }
1201 if (covered) {
1202 return new BindingPattern(rpOne.recordType);
1203 } else if (reducedNestedPatterns != null) {
1204 return new RecordPattern(rpOne.recordType, rpOne.fullComponentTypes(), reducedNestedPatterns);
1205 }
1206 }
1207 return pattern;
1208 }
1209
1210 private Set<PatternDescription> removeCoveredRecordPatterns(Set<PatternDescription> patterns) {
1211 Set<Symbol> existingBindings = patterns.stream()
1212 .filter(pd -> pd instanceof BindingPattern)
1213 .map(pd -> ((BindingPattern) pd).type.tsym)
1214 .collect(Collectors.toSet());
1215 Set<PatternDescription> result = new HashSet<>(patterns);
1216
1217 for (Iterator<PatternDescription> it = result.iterator(); it.hasNext();) {
1218 PatternDescription pd = it.next();
1219 if (pd instanceof RecordPattern rp && existingBindings.contains(rp.recordType.tsym)) {
1220 it.remove();
1221 }
1222 }
1223
1224 return result;
1225 }
1226
1227 public void visitTry(JCTry tree) {
1228 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1229 pendingExits = new ListBuffer<>();
1230 for (JCTree resource : tree.resources) {
1231 if (resource instanceof JCVariableDecl variableDecl) {
1232 visitVarDef(variableDecl);
1233 } else if (resource instanceof JCExpression expression) {
1234 scan(expression);
1235 } else {
1236 throw new AssertionError(tree); // parser error
1237 }
1238 }
1239
1240 scanStat(tree.body);
1241 Liveness aliveEnd = alive;
1242
1243 for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
1244 alive = Liveness.ALIVE;
1245 JCVariableDecl param = l.head.param;
1246 scan(param);
1247 scanStat(l.head.body);
1248 aliveEnd = aliveEnd.or(alive);
1249 }
1250 if (tree.finalizer != null) {
1251 ListBuffer<PendingExit> exits = pendingExits;
1252 pendingExits = prevPendingExits;
1253 alive = Liveness.ALIVE;
1254 scanStat(tree.finalizer);
1255 tree.finallyCanCompleteNormally = alive != Liveness.DEAD;
1256 if (alive == Liveness.DEAD) {
1257 lint.logIfEnabled(TreeInfo.diagEndPos(tree.finalizer),
1258 LintWarnings.FinallyCannotComplete);
1259 } else {
1260 while (exits.nonEmpty()) {
1261 pendingExits.append(exits.next());
1262 }
1263 alive = aliveEnd;
1264 }
1265 } else {
1266 alive = aliveEnd;
1267 ListBuffer<PendingExit> exits = pendingExits;
1268 pendingExits = prevPendingExits;
1269 while (exits.nonEmpty()) pendingExits.append(exits.next());
1270 }
1271 }
1272
1273 @Override
1274 public void visitIf(JCIf tree) {
1275 scan(tree.cond);
1276 scanStat(tree.thenpart);
1277 if (tree.elsepart != null) {
1278 Liveness aliveAfterThen = alive;
1279 alive = Liveness.ALIVE;
1280 scanStat(tree.elsepart);
1281 alive = alive.or(aliveAfterThen);
1282 } else {
1283 alive = Liveness.ALIVE;
1284 }
1285 }
1286
1287 public void visitBreak(JCBreak tree) {
1288 recordExit(new PendingExit(tree));
1289 }
1290
1291 @Override
1292 public void visitYield(JCYield tree) {
1293 scan(tree.value);
1294 recordExit(new PendingExit(tree));
1295 }
1296
1297 public void visitContinue(JCContinue tree) {
1298 recordExit(new PendingExit(tree));
1299 }
1300
1301 public void visitReturn(JCReturn tree) {
1302 scan(tree.expr);
1303 recordExit(new PendingExit(tree));
1304 }
1305
1306 public void visitThrow(JCThrow tree) {
1307 scan(tree.expr);
1308 markDead();
1309 }
1310
1311 public void visitApply(JCMethodInvocation tree) {
1312 scan(tree.meth);
1313 scan(tree.args);
1314 }
1315
1316 public void visitNewClass(JCNewClass tree) {
1317 scan(tree.encl);
1318 scan(tree.args);
1319 if (tree.def != null) {
1320 scan(tree.def);
1321 }
1322 }
1323
1324 @Override
1325 public void visitLambda(JCLambda tree) {
1326 if (tree.type != null &&
1327 tree.type.isErroneous()) {
1328 return;
1329 }
1330
1331 ListBuffer<PendingExit> prevPending = pendingExits;
1332 Liveness prevAlive = alive;
1333 try {
1334 pendingExits = new ListBuffer<>();
1335 alive = Liveness.ALIVE;
1336 scanStat(tree.body);
1337 tree.canCompleteNormally = alive != Liveness.DEAD;
1338 }
1339 finally {
1340 pendingExits = prevPending;
1341 alive = prevAlive;
1342 }
1343 }
1344
1345 public void visitModuleDef(JCModuleDecl tree) {
1346 // Do nothing for modules
1347 }
1348
1349 /* ************************************************************************
1350 * main method
1351 *************************************************************************/
1352
1353 /** Perform definite assignment/unassignment analysis on a tree.
1354 */
1355 public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
1356 analyzeTree(env, env.tree, make);
1357 }
1358 public void analyzeTree(Env<AttrContext> env, JCTree tree, TreeMaker make) {
1359 try {
1360 attrEnv = env;
1361 Flow.this.make = make;
1362 pendingExits = new ListBuffer<>();
1363 alive = Liveness.ALIVE;
1364 scan(tree);
1365 } finally {
1366 pendingExits = null;
1367 Flow.this.make = null;
1368 }
1369 }
1370 }
1371
1372 private boolean isBpCovered(Type componentType, PatternDescription newNested) {
1373 if (newNested instanceof BindingPattern bp) {
1374 Type seltype = types.erasure(componentType);
1375 Type pattype = types.erasure(bp.type);
1376
1377 return seltype.isPrimitive() ?
1378 types.isUnconditionallyExact(seltype, pattype) :
1379 (bp.type.isPrimitive() && types.isUnconditionallyExact(types.unboxedType(seltype), bp.type)) || types.isSubtype(seltype, pattype);
1380 }
1381 return false;
1382 }
1383
1384 /**
1385 * This pass implements the second step of the dataflow analysis, namely
1386 * the exception analysis. This is to ensure that every checked exception that is
1387 * thrown is declared or caught. The analyzer uses some info that has been set by
1388 * the liveliness analyzer.
1389 */
1390 class FlowAnalyzer extends BaseAnalyzer {
1391
1392 /** A flag that indicates whether the last statement could
1393 * complete normally.
1394 */
1395 HashMap<Symbol, List<Type>> preciseRethrowTypes;
1396
1397 /** The current class being defined.
1398 */
1399 JCClassDecl classDef;
1400
1401 /** The list of possibly thrown declarable exceptions.
1402 */
1403 List<Type> thrown;
1404
1405 /** The list of exceptions that are either caught or declared to be
1406 * thrown.
1407 */
1408 List<Type> caught;
1409
1410 class ThrownPendingExit extends BaseAnalyzer.PendingExit {
1411
1412 Type thrown;
1413
1414 ThrownPendingExit(JCTree tree, Type thrown) {
1415 super(tree);
1416 this.thrown = thrown;
1417 }
1418 }
1419
1420 @Override
1421 void markDead() {
1422 //do nothing
1423 }
1424
1425 /*-------------------- Exceptions ----------------------*/
1426
1427 /** Complain that pending exceptions are not caught.
1428 */
1429 void errorUncaught() {
1430 for (PendingExit exit = pendingExits.next();
1431 exit != null;
1432 exit = pendingExits.next()) {
1433 if (exit instanceof ThrownPendingExit thrownExit) {
1434 if (classDef != null &&
1435 classDef.pos == exit.tree.pos) {
1436 log.error(exit.tree.pos(),
1437 Errors.UnreportedExceptionDefaultConstructor(thrownExit.thrown));
1438 } else if (exit.tree.hasTag(VARDEF) &&
1439 ((JCVariableDecl)exit.tree).sym.isResourceVariable()) {
1440 log.error(exit.tree.pos(),
1441 Errors.UnreportedExceptionImplicitClose(thrownExit.thrown,
1442 ((JCVariableDecl)exit.tree).sym.name));
1443 } else {
1444 log.error(exit.tree.pos(),
1445 Errors.UnreportedExceptionNeedToCatchOrThrow(thrownExit.thrown));
1446 }
1447 } else {
1448 Assert.check(log.hasErrorOn(exit.tree.pos()));
1449 }
1450 }
1451 }
1452
1453 /** Record that exception is potentially thrown and check that it
1454 * is caught.
1455 */
1456 void markThrown(JCTree tree, Type exc) {
1457 if (!chk.isUnchecked(tree.pos(), exc)) {
1458 if (!chk.isHandled(exc, caught)) {
1459 pendingExits.append(new ThrownPendingExit(tree, exc));
1460 }
1461 thrown = chk.incl(exc, thrown);
1462 }
1463 }
1464
1465 /* ***********************************************************************
1466 * Visitor methods for statements and definitions
1467 *************************************************************************/
1468
1469 /* ------------ Visitor methods for various sorts of trees -------------*/
1470
1471 public void visitClassDef(JCClassDecl tree) {
1472 if (tree.sym == null) return;
1473
1474 JCClassDecl classDefPrev = classDef;
1475 List<Type> thrownPrev = thrown;
1476 List<Type> caughtPrev = caught;
1477 ListBuffer<PendingExit> pendingExitsPrev = pendingExits;
1478 Lint lintPrev = lint;
1479 boolean anonymousClass = tree.name == names.empty;
1480 pendingExits = new ListBuffer<>();
1481 if (!anonymousClass) {
1482 caught = List.nil();
1483 }
1484 classDef = tree;
1485 thrown = List.nil();
1486 lint = lint.augment(tree.sym);
1487
1488 try {
1489 // process all the nested classes
1490 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
1491 if (l.head.hasTag(CLASSDEF)) {
1492 scan(l.head);
1493 }
1494 }
1495
1496 // process all the static initializers
1497 forEachInitializer(tree, true, def -> {
1498 scan(def);
1499 errorUncaught();
1500 });
1501
1502 // in an anonymous class, add the set of thrown exceptions to
1503 // the throws clause of the synthetic constructor and propagate
1504 // outwards.
1505 // Changing the throws clause on the fly is okay here because
1506 // the anonymous constructor can't be invoked anywhere else,
1507 // and its type hasn't been cached.
1508 if (anonymousClass) {
1509 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
1510 if (TreeInfo.isConstructor(l.head)) {
1511 JCMethodDecl mdef = (JCMethodDecl)l.head;
1512 scan(mdef);
1513 mdef.thrown = make.Types(thrown);
1514 mdef.sym.type = types.createMethodTypeWithThrown(mdef.sym.type, thrown);
1515 }
1516 }
1517 thrownPrev = chk.union(thrown, thrownPrev);
1518 }
1519
1520 // process all the methods
1521 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
1522 if (anonymousClass && TreeInfo.isConstructor(l.head))
1523 continue; // there can never be an uncaught exception.
1524 if (l.head.hasTag(METHODDEF)) {
1525 scan(l.head);
1526 errorUncaught();
1527 }
1528 }
1529
1530 thrown = thrownPrev;
1531 } finally {
1532 pendingExits = pendingExitsPrev;
1533 caught = caughtPrev;
1534 classDef = classDefPrev;
1535 lint = lintPrev;
1536 }
1537 }
1538
1539 public void visitMethodDef(JCMethodDecl tree) {
1540 if (tree.body == null) return;
1541
1542 List<Type> caughtPrev = caught;
1543 List<Type> mthrown = tree.sym.type.getThrownTypes();
1544 Lint lintPrev = lint;
1545
1546 lint = lint.augment(tree.sym);
1547
1548 Assert.check(pendingExits.isEmpty());
1549
1550 try {
1551 for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
1552 JCVariableDecl def = l.head;
1553 scan(def);
1554 }
1555 if (TreeInfo.hasConstructorCall(tree, names._super))
1556 caught = chk.union(caught, mthrown);
1557 else if ((tree.sym.flags() & (BLOCK | STATIC)) != BLOCK)
1558 caught = mthrown;
1559 // else we are in an instance initializer block;
1560 // leave caught unchanged.
1561
1562 scan(tree.body);
1563
1564 List<PendingExit> exits = pendingExits.toList();
1565 pendingExits = new ListBuffer<>();
1566 while (exits.nonEmpty()) {
1567 PendingExit exit = exits.head;
1568 exits = exits.tail;
1569 if (!(exit instanceof ThrownPendingExit)) {
1570 Assert.check(exit.tree.hasTag(RETURN) ||
1571 log.hasErrorOn(exit.tree.pos()));
1572 } else {
1573 // uncaught throws will be reported later
1574 pendingExits.append(exit);
1575 }
1576 }
1577 } finally {
1578 caught = caughtPrev;
1579 lint = lintPrev;
1580 }
1581 }
1582
1583 public void visitVarDef(JCVariableDecl tree) {
1584 if (tree.init != null) {
1585 Lint lintPrev = lint;
1586 lint = lint.augment(tree.sym);
1587 try{
1588 scan(tree.init);
1589 } finally {
1590 lint = lintPrev;
1591 }
1592 }
1593 }
1594
1595 public void visitBlock(JCBlock tree) {
1596 scan(tree.stats);
1597 }
1598
1599 public void visitDoLoop(JCDoWhileLoop tree) {
1600 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1601 pendingExits = new ListBuffer<>();
1602 scan(tree.body);
1603 resolveContinues(tree);
1604 scan(tree.cond);
1605 resolveBreaks(tree, prevPendingExits);
1606 }
1607
1608 public void visitWhileLoop(JCWhileLoop tree) {
1609 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1610 pendingExits = new ListBuffer<>();
1611 scan(tree.cond);
1612 scan(tree.body);
1613 resolveContinues(tree);
1614 resolveBreaks(tree, prevPendingExits);
1615 }
1616
1617 public void visitForLoop(JCForLoop tree) {
1618 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1619 scan(tree.init);
1620 pendingExits = new ListBuffer<>();
1621 if (tree.cond != null) {
1622 scan(tree.cond);
1623 }
1624 scan(tree.body);
1625 resolveContinues(tree);
1626 scan(tree.step);
1627 resolveBreaks(tree, prevPendingExits);
1628 }
1629
1630 public void visitForeachLoop(JCEnhancedForLoop tree) {
1631 visitVarDef(tree.var);
1632 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1633 scan(tree.expr);
1634 pendingExits = new ListBuffer<>();
1635 scan(tree.body);
1636 resolveContinues(tree);
1637 resolveBreaks(tree, prevPendingExits);
1638 }
1639
1640 public void visitLabelled(JCLabeledStatement tree) {
1641 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1642 pendingExits = new ListBuffer<>();
1643 scan(tree.body);
1644 resolveBreaks(tree, prevPendingExits);
1645 }
1646
1647 public void visitSwitch(JCSwitch tree) {
1648 handleSwitch(tree, tree.selector, tree.cases);
1649 }
1650
1651 @Override
1652 public void visitSwitchExpression(JCSwitchExpression tree) {
1653 handleSwitch(tree, tree.selector, tree.cases);
1654 }
1655
1656 private void handleSwitch(JCTree tree, JCExpression selector, List<JCCase> cases) {
1657 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1658 pendingExits = new ListBuffer<>();
1659 scan(selector);
1660 for (List<JCCase> l = cases; l.nonEmpty(); l = l.tail) {
1661 JCCase c = l.head;
1662 scan(c.labels);
1663 scan(c.stats);
1664 }
1665 if (tree.hasTag(SWITCH_EXPRESSION)) {
1666 resolveYields(tree, prevPendingExits);
1667 } else {
1668 resolveBreaks(tree, prevPendingExits);
1669 }
1670 }
1671
1672 public void visitTry(JCTry tree) {
1673 List<Type> caughtPrev = caught;
1674 List<Type> thrownPrev = thrown;
1675 thrown = List.nil();
1676 for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
1677 List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
1678 ((JCTypeUnion)l.head.param.vartype).alternatives :
1679 List.of(l.head.param.vartype);
1680 for (JCExpression ct : subClauses) {
1681 caught = chk.incl(ct.type, caught);
1682 }
1683 }
1684
1685 ListBuffer<PendingExit> prevPendingExits = pendingExits;
1686 pendingExits = new ListBuffer<>();
1687 for (JCTree resource : tree.resources) {
1688 if (resource instanceof JCVariableDecl variableDecl) {
1689 visitVarDef(variableDecl);
1690 } else if (resource instanceof JCExpression expression) {
1691 scan(expression);
1692 } else {
1693 throw new AssertionError(tree); // parser error
1694 }
1695 }
1696 for (JCTree resource : tree.resources) {
1697 List<Type> closeableSupertypes = resource.type.isCompound() ?
1698 types.interfaces(resource.type).prepend(types.supertype(resource.type)) :
1699 List.of(resource.type);
1700 for (Type sup : closeableSupertypes) {
1701 if (types.asSuper(sup, syms.autoCloseableType.tsym) != null) {
1702 Symbol closeMethod = rs.resolveQualifiedMethod(tree,
1703 attrEnv,
1704 types.skipTypeVars(sup, false),
1705 names.close,
1706 List.nil(),
1707 List.nil());
1708 Type mt = types.memberType(resource.type, closeMethod);
1709 if (closeMethod.kind == MTH) {
1710 for (Type t : mt.getThrownTypes()) {
1711 markThrown(resource, t);
1712 }
1713 }
1714 }
1715 }
1716 }
1717 scan(tree.body);
1718 List<Type> thrownInTry = chk.union(thrown, List.of(syms.runtimeExceptionType, syms.errorType));
1719 thrown = thrownPrev;
1720 caught = caughtPrev;
1721
1722 List<Type> caughtInTry = List.nil();
1723 for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
1724 JCVariableDecl param = l.head.param;
1725 List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
1726 ((JCTypeUnion)l.head.param.vartype).alternatives :
1727 List.of(l.head.param.vartype);
1728 List<Type> ctypes = List.nil();
1729 List<Type> rethrownTypes = chk.diff(thrownInTry, caughtInTry);
1730 for (JCExpression ct : subClauses) {
1731 Type exc = ct.type;
1732 if (exc != syms.unknownType) {
1733 ctypes = ctypes.append(exc);
1734 if (types.isSameType(exc, syms.objectType))
1735 continue;
1736 var pos = subClauses.size() > 1 ? ct.pos() : l.head.pos();
1737 checkCaughtType(pos, exc, thrownInTry, caughtInTry);
1738 caughtInTry = chk.incl(exc, caughtInTry);
1739 }
1740 }
1741 scan(param);
1742 preciseRethrowTypes.put(param.sym, chk.intersect(ctypes, rethrownTypes));
1743 scan(l.head.body);
1744 preciseRethrowTypes.remove(param.sym);
1745 }
1746 if (tree.finalizer != null) {
1747 List<Type> savedThrown = thrown;
1748 thrown = List.nil();
1749 ListBuffer<PendingExit> exits = pendingExits;
1750 pendingExits = prevPendingExits;
1751 scan(tree.finalizer);
1752 if (!tree.finallyCanCompleteNormally) {
1753 // discard exits and exceptions from try and finally
1754 thrown = chk.union(thrown, thrownPrev);
1755 } else {
1756 thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry));
1757 thrown = chk.union(thrown, savedThrown);
1758 // FIX: this doesn't preserve source order of exits in catch
1759 // versus finally!
1760 while (exits.nonEmpty()) {
1761 pendingExits.append(exits.next());
1762 }
1763 }
1764 } else {
1765 thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry));
1766 ListBuffer<PendingExit> exits = pendingExits;
1767 pendingExits = prevPendingExits;
1768 while (exits.nonEmpty()) pendingExits.append(exits.next());
1769 }
1770 }
1771
1772 @Override
1773 public void visitIf(JCIf tree) {
1774 scan(tree.cond);
1775 scan(tree.thenpart);
1776 if (tree.elsepart != null) {
1777 scan(tree.elsepart);
1778 }
1779 }
1780
1781 void checkCaughtType(DiagnosticPosition pos, Type exc, List<Type> thrownInTry, List<Type> caughtInTry) {
1782 if (chk.subset(exc, caughtInTry)) {
1783 log.error(pos, Errors.ExceptAlreadyCaught(exc));
1784 } else if (!chk.isUnchecked(pos, exc) &&
1785 !isExceptionOrThrowable(exc) &&
1786 !chk.intersects(exc, thrownInTry)) {
1787 log.error(pos, Errors.ExceptNeverThrownInTry(exc));
1788 } else {
1789 List<Type> catchableThrownTypes = chk.intersect(List.of(exc), thrownInTry);
1790 // 'catchableThrownTypes' cannot possibly be empty - if 'exc' was an
1791 // unchecked exception, the result list would not be empty, as the augmented
1792 // thrown set includes { RuntimeException, Error }; if 'exc' was a checked
1793 // exception, that would have been covered in the branch above
1794 if (chk.diff(catchableThrownTypes, caughtInTry).isEmpty() &&
1795 !isExceptionOrThrowable(exc)) {
1796 Warning key = catchableThrownTypes.length() == 1 ?
1797 Warnings.UnreachableCatch(catchableThrownTypes) :
1798 Warnings.UnreachableCatch1(catchableThrownTypes);
1799 log.warning(pos, key);
1800 }
1801 }
1802 }
1803 //where
1804 private boolean isExceptionOrThrowable(Type exc) {
1805 return exc.tsym == syms.throwableType.tsym ||
1806 exc.tsym == syms.exceptionType.tsym;
1807 }
1808
1809 public void visitBreak(JCBreak tree) {
1810 recordExit(new PendingExit(tree));
1811 }
1812
1813 public void visitYield(JCYield tree) {
1814 scan(tree.value);
1815 recordExit(new PendingExit(tree));
1816 }
1817
1818 public void visitContinue(JCContinue tree) {
1819 recordExit(new PendingExit(tree));
1820 }
1821
1822 public void visitReturn(JCReturn tree) {
1823 scan(tree.expr);
1824 recordExit(new PendingExit(tree));
1825 }
1826
1827 public void visitThrow(JCThrow tree) {
1828 scan(tree.expr);
1829 Symbol sym = TreeInfo.symbol(tree.expr);
1830 if (sym != null &&
1831 sym.kind == VAR &&
1832 (sym.flags() & (FINAL | EFFECTIVELY_FINAL)) != 0 &&
1833 preciseRethrowTypes.get(sym) != null) {
1834 for (Type t : preciseRethrowTypes.get(sym)) {
1835 markThrown(tree, t);
1836 }
1837 }
1838 else {
1839 markThrown(tree, tree.expr.type);
1840 }
1841 markDead();
1842 }
1843
1844 public void visitApply(JCMethodInvocation tree) {
1845 scan(tree.meth);
1846 scan(tree.args);
1847
1848 // Mark as thrown the exceptions thrown by the method being invoked
1849 for (List<Type> l = tree.meth.type.getThrownTypes(); l.nonEmpty(); l = l.tail)
1850 markThrown(tree, l.head);
1851
1852 // After super(), scan initializers to uncover any exceptions they throw
1853 if (TreeInfo.name(tree.meth) == names._super) {
1854 forEachInitializer(classDef, false, def -> {
1855 scan(def);
1856 errorUncaught();
1857 });
1858 }
1859 }
1860
1861 public void visitNewClass(JCNewClass tree) {
1862 scan(tree.encl);
1863 scan(tree.args);
1864 // scan(tree.def);
1865 for (List<Type> l = tree.constructorType.getThrownTypes();
1866 l.nonEmpty();
1867 l = l.tail) {
1868 markThrown(tree, l.head);
1869 }
1870 List<Type> caughtPrev = caught;
1871 try {
1872 // If the new class expression defines an anonymous class,
1873 // analysis of the anonymous constructor may encounter thrown
1874 // types which are unsubstituted type variables.
1875 // However, since the constructor's actual thrown types have
1876 // already been marked as thrown, it is safe to simply include
1877 // each of the constructor's formal thrown types in the set of
1878 // 'caught/declared to be thrown' types, for the duration of
1879 // the class def analysis.
1880 if (tree.def != null)
1881 for (List<Type> l = tree.constructor.type.getThrownTypes();
1882 l.nonEmpty();
1883 l = l.tail) {
1884 caught = chk.incl(l.head, caught);
1885 }
1886 scan(tree.def);
1887 }
1888 finally {
1889 caught = caughtPrev;
1890 }
1891 }
1892
1893 @Override
1894 public void visitLambda(JCLambda tree) {
1895 if (tree.type != null &&
1896 tree.type.isErroneous()) {
1897 return;
1898 }
1899 List<Type> prevCaught = caught;
1900 List<Type> prevThrown = thrown;
1901 ListBuffer<PendingExit> prevPending = pendingExits;
1902 try {
1903 pendingExits = new ListBuffer<>();
1904 caught = tree.getDescriptorType(types).getThrownTypes();
1905 thrown = List.nil();
1906 scan(tree.body);
1907 List<PendingExit> exits = pendingExits.toList();
1908 pendingExits = new ListBuffer<>();
1909 while (exits.nonEmpty()) {
1910 PendingExit exit = exits.head;
1911 exits = exits.tail;
1912 if (!(exit instanceof ThrownPendingExit)) {
1913 Assert.check(exit.tree.hasTag(RETURN) ||
1914 log.hasErrorOn(exit.tree.pos()));
1915 } else {
1916 // uncaught throws will be reported later
1917 pendingExits.append(exit);
1918 }
1919 }
1920
1921 errorUncaught();
1922 } finally {
1923 pendingExits = prevPending;
1924 caught = prevCaught;
1925 thrown = prevThrown;
1926 }
1927 }
1928
1929 public void visitModuleDef(JCModuleDecl tree) {
1930 // Do nothing for modules
1931 }
1932
1933 /* ************************************************************************
1934 * main method
1935 *************************************************************************/
1936
1937 /** Perform definite assignment/unassignment analysis on a tree.
1938 */
1939 public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
1940 analyzeTree(env, env.tree, make);
1941 }
1942 public void analyzeTree(Env<AttrContext> env, JCTree tree, TreeMaker make) {
1943 try {
1944 attrEnv = env;
1945 Flow.this.make = make;
1946 pendingExits = new ListBuffer<>();
1947 preciseRethrowTypes = new HashMap<>();
1948 this.thrown = this.caught = null;
1949 this.classDef = null;
1950 scan(tree);
1951 } finally {
1952 pendingExits = null;
1953 Flow.this.make = null;
1954 this.thrown = this.caught = null;
1955 this.classDef = null;
1956 }
1957 }
1958 }
1959
1960 /**
1961 * Specialized pass that performs reachability analysis on a lambda
1962 */
1963 class LambdaAliveAnalyzer extends AliveAnalyzer {
1964
1965 boolean inLambda;
1966
1967 @Override
1968 public void visitReturn(JCReturn tree) {
1969 //ignore lambda return expression (which might not even be attributed)
1970 recordExit(new PendingExit(tree));
1971 }
1972
1973 @Override
1974 public void visitLambda(JCLambda tree) {
1975 if (inLambda || tree.getBodyKind() == BodyKind.EXPRESSION) {
1976 return;
1977 }
1978 inLambda = true;
1979 try {
1980 super.visitLambda(tree);
1981 } finally {
1982 inLambda = false;
1983 }
1984 }
1985
1986 @Override
1987 public void visitClassDef(JCClassDecl tree) {
1988 //skip
1989 }
1990 }
1991
1992 /**
1993 * Determine if alive after the given tree.
1994 */
1995 class SnippetAliveAnalyzer extends AliveAnalyzer {
1996 @Override
1997 public void visitClassDef(JCClassDecl tree) {
1998 //skip
1999 }
2000 @Override
2001 public void visitLambda(JCLambda tree) {
2002 //skip
2003 }
2004 public boolean isAlive() {
2005 return super.alive != Liveness.DEAD;
2006 }
2007 }
2008
2009 class SnippetBreakToAnalyzer extends AliveAnalyzer {
2010 private final JCTree breakTo;
2011 private boolean breaksTo;
2012
2013 public SnippetBreakToAnalyzer(JCTree breakTo) {
2014 this.breakTo = breakTo;
2015 }
2016
2017 @Override
2018 public void visitBreak(JCBreak tree) {
2019 breaksTo |= breakTo == tree.target && super.alive == Liveness.ALIVE;
2020 }
2021
2022 public boolean breaksTo() {
2023 return breaksTo;
2024 }
2025 }
2026
2027 /**
2028 * Specialized pass that performs DA/DU on a lambda
2029 */
2030 class LambdaAssignAnalyzer extends AssignAnalyzer {
2031 WriteableScope enclosedSymbols;
2032 boolean inLambda;
2033
2034 LambdaAssignAnalyzer(Env<AttrContext> env) {
2035 enclosedSymbols = WriteableScope.create(env.enclClass.sym);
2036 }
2037
2038 @Override
2039 public void visitLambda(JCLambda tree) {
2040 if (inLambda) {
2041 return;
2042 }
2043 inLambda = true;
2044 try {
2045 super.visitLambda(tree);
2046 } finally {
2047 inLambda = false;
2048 }
2049 }
2050
2051 @Override
2052 public void visitVarDef(JCVariableDecl tree) {
2053 enclosedSymbols.enter(tree.sym);
2054 super.visitVarDef(tree);
2055 }
2056 @Override
2057 protected boolean trackable(VarSymbol sym) {
2058 return enclosedSymbols.includes(sym) &&
2059 sym.owner.kind == MTH;
2060 }
2061
2062 @Override
2063 public void visitClassDef(JCClassDecl tree) {
2064 //skip
2065 }
2066 }
2067
2068 /**
2069 * Specialized pass that performs inference of thrown types for lambdas.
2070 */
2071 class LambdaFlowAnalyzer extends FlowAnalyzer {
2072 List<Type> inferredThrownTypes;
2073 boolean inLambda;
2074 @Override
2075 public void visitLambda(JCLambda tree) {
2076 if ((tree.type != null &&
2077 tree.type.isErroneous()) || inLambda) {
2078 return;
2079 }
2080 List<Type> prevCaught = caught;
2081 List<Type> prevThrown = thrown;
2082 ListBuffer<PendingExit> prevPending = pendingExits;
2083 inLambda = true;
2084 try {
2085 pendingExits = new ListBuffer<>();
2086 caught = List.of(syms.throwableType);
2087 thrown = List.nil();
2088 scan(tree.body);
2089 inferredThrownTypes = thrown;
2090 } finally {
2091 pendingExits = prevPending;
2092 caught = prevCaught;
2093 thrown = prevThrown;
2094 inLambda = false;
2095 }
2096 }
2097 @Override
2098 public void visitClassDef(JCClassDecl tree) {
2099 //skip
2100 }
2101 }
2102
2103 /**
2104 * This pass implements (i) definite assignment analysis, which ensures that
2105 * each variable is assigned when used and (ii) definite unassignment analysis,
2106 * which ensures that no final variable is assigned more than once. This visitor
2107 * depends on the results of the liveliness analyzer. This pass is also used to mark
2108 * effectively-final local variables/parameters.
2109 */
2110
2111 public class AssignAnalyzer extends BaseAnalyzer {
2112
2113 /** The set of definitely assigned variables.
2114 */
2115 final Bits inits;
2116
2117 /** The set of definitely unassigned variables.
2118 */
2119 final Bits uninits;
2120
2121 /** The set of variables that are definitely unassigned everywhere
2122 * in current try block. This variable is maintained lazily; it is
2123 * updated only when something gets removed from uninits,
2124 * typically by being assigned in reachable code. To obtain the
2125 * correct set of variables which are definitely unassigned
2126 * anywhere in current try block, intersect uninitsTry and
2127 * uninits.
2128 */
2129 final Bits uninitsTry;
2130
2131 /** When analyzing a condition, inits and uninits are null.
2132 * Instead we have:
2133 */
2134 final Bits initsWhenTrue;
2135 final Bits initsWhenFalse;
2136 final Bits uninitsWhenTrue;
2137 final Bits uninitsWhenFalse;
2138
2139 /** A mapping from addresses to variable symbols.
2140 */
2141 protected JCVariableDecl[] vardecls;
2142
2143 /** The current class being defined.
2144 */
2145 JCClassDecl classDef;
2146
2147 /** The first variable sequence number in this class definition.
2148 */
2149 int firstadr;
2150
2151 /** The next available variable sequence number.
2152 */
2153 protected int nextadr;
2154
2155 /** The first variable sequence number in a block that can return.
2156 */
2157 protected int returnadr;
2158
2159 /** The list of unreferenced automatic resources.
2160 */
2161 WriteableScope unrefdResources;
2162
2163 /** Modified when processing a loop body the second time for DU analysis. */
2164 FlowKind flowKind = FlowKind.NORMAL;
2165
2166 /** The starting position of the analyzed tree */
2167 int startPos;
2168
2169 public class AssignPendingExit extends BaseAnalyzer.PendingExit {
2170
2171 final Bits inits;
2172 final Bits uninits;
2173 final Bits exit_inits = new Bits(true);
2174 final Bits exit_uninits = new Bits(true);
2175
2176 public AssignPendingExit(JCTree tree, final Bits inits, final Bits uninits) {
2177 super(tree);
2178 this.inits = inits;
2179 this.uninits = uninits;
2180 this.exit_inits.assign(inits);
2181 this.exit_uninits.assign(uninits);
2182 }
2183
2184 @Override
2185 public void resolveJump() {
2186 inits.andSet(exit_inits);
2187 uninits.andSet(exit_uninits);
2188 }
2189 }
2190
2191 public AssignAnalyzer() {
2192 this.inits = new Bits();
2193 uninits = new Bits();
2194 uninitsTry = new Bits();
2195 initsWhenTrue = new Bits(true);
2196 initsWhenFalse = new Bits(true);
2197 uninitsWhenTrue = new Bits(true);
2198 uninitsWhenFalse = new Bits(true);
2199 }
2200
2201 private boolean isConstructor;
2202
2203 @Override
2204 protected void markDead() {
2205 inits.inclRange(returnadr, nextadr);
2206 uninits.inclRange(returnadr, nextadr);
2207 }
2208
2209 /*-------------- Processing variables ----------------------*/
2210
2211 /** Do we need to track init/uninit state of this symbol?
2212 * I.e. is symbol either a local or a blank final variable?
2213 */
2214 protected boolean trackable(VarSymbol sym) {
2215 return
2216 sym.pos >= startPos &&
2217 ((sym.owner.kind == MTH || sym.owner.kind == VAR ||
2218 isFinalOrStrictUninitializedField(sym)));
2219 }
2220
2221 boolean isFinalOrStrictUninitializedField(VarSymbol sym) {
2222 return sym.owner.kind == TYP &&
2223 (((sym.flags() & (FINAL | HASINIT | PARAMETER)) == FINAL ||
2224 (sym.flags() & (STRICT | HASINIT | PARAMETER)) == STRICT) &&
2225 classDef.sym.isEnclosedBy((ClassSymbol)sym.owner));
2226 }
2227
2228 /** Initialize new trackable variable by setting its address field
2229 * to the next available sequence number and entering it under that
2230 * index into the vars array.
2231 */
2232 void newVar(JCVariableDecl varDecl) {
2233 VarSymbol sym = varDecl.sym;
2234 vardecls = ArrayUtils.ensureCapacity(vardecls, nextadr);
2235 if ((sym.flags() & FINAL) == 0) {
2236 sym.flags_field |= EFFECTIVELY_FINAL;
2237 }
2238 sym.adr = nextadr;
2239 vardecls[nextadr] = varDecl;
2240 inits.excl(nextadr);
2241 uninits.incl(nextadr);
2242 nextadr++;
2243 }
2244
2245 /** Record an initialization of a trackable variable.
2246 */
2247 void letInit(DiagnosticPosition pos, VarSymbol sym) {
2248 if (sym.adr >= firstadr && trackable(sym)) {
2249 if ((sym.flags() & EFFECTIVELY_FINAL) != 0) {
2250 if (!uninits.isMember(sym.adr)) {
2251 //assignment targeting an effectively final variable
2252 //makes the variable lose its status of effectively final
2253 //if the variable is _not_ definitively unassigned
2254 sym.flags_field &= ~EFFECTIVELY_FINAL;
2255 } else {
2256 uninit(sym);
2257 }
2258 }
2259 else if ((sym.flags() & FINAL) != 0) {
2260 if ((sym.flags() & PARAMETER) != 0) {
2261 if ((sym.flags() & UNION) != 0) { //multi-catch parameter
2262 log.error(pos, Errors.MulticatchParameterMayNotBeAssigned(sym));
2263 }
2264 else {
2265 log.error(pos,
2266 Errors.FinalParameterMayNotBeAssigned(sym));
2267 }
2268 } else if (!uninits.isMember(sym.adr)) {
2269 log.error(pos, diags.errorKey(flowKind.errKey, sym));
2270 } else {
2271 uninit(sym);
2272 }
2273 }
2274 inits.incl(sym.adr);
2275 } else if ((sym.flags() & FINAL) != 0) {
2276 log.error(pos, Errors.VarMightAlreadyBeAssigned(sym));
2277 }
2278 }
2279 //where
2280 void uninit(VarSymbol sym) {
2281 if (!inits.isMember(sym.adr)) {
2282 // reachable assignment
2283 uninits.excl(sym.adr);
2284 uninitsTry.excl(sym.adr);
2285 } else {
2286 //log.rawWarning(pos, "unreachable assignment");//DEBUG
2287 uninits.excl(sym.adr);
2288 }
2289 }
2290
2291 /** If tree is either a simple name or of the form this.name or
2292 * C.this.name, and tree represents a trackable variable,
2293 * record an initialization of the variable.
2294 */
2295 void letInit(JCTree tree) {
2296 letInit(tree, (JCAssign) null);
2297 }
2298
2299 void letInit(JCTree tree, JCAssign assign) {
2300 tree = TreeInfo.skipParens(tree);
2301 if (tree.hasTag(IDENT) || tree.hasTag(SELECT)) {
2302 Symbol sym = TreeInfo.symbol(tree);
2303 if (sym.kind == VAR) {
2304 letInit(tree.pos(), (VarSymbol)sym);
2305 if (isConstructor && sym.isStrict()) {
2306 /* we are initializing a strict field inside of a constructor, we now need to find which fields
2307 * haven't been initialized yet
2308 */
2309 unsetFieldsInfo.addUnsetFieldsInfo(classDef.sym, assign != null ? assign : tree, findUninitStrictFields());
2310 }
2311 }
2312 }
2313 }
2314
2315 /** Check that trackable variable is initialized.
2316 */
2317 void checkInit(DiagnosticPosition pos, VarSymbol sym) {
2318 checkInit(pos, sym, Errors.VarMightNotHaveBeenInitialized(sym));
2319 }
2320
2321 void checkInit(DiagnosticPosition pos, VarSymbol sym, Error errkey) {
2322 if ((sym.adr >= firstadr || sym.owner.kind != TYP) &&
2323 trackable(sym) &&
2324 !inits.isMember(sym.adr) &&
2325 (sym.flags_field & CLASH) == 0) {
2326 log.error(pos, errkey);
2327 inits.incl(sym.adr);
2328 }
2329 }
2330
2331 /** Utility method to reset several Bits instances.
2332 */
2333 private void resetBits(Bits... bits) {
2334 for (Bits b : bits) {
2335 b.reset();
2336 }
2337 }
2338
2339 /** Split (duplicate) inits/uninits into WhenTrue/WhenFalse sets
2340 */
2341 void split(boolean setToNull) {
2342 initsWhenFalse.assign(inits);
2343 uninitsWhenFalse.assign(uninits);
2344 initsWhenTrue.assign(inits);
2345 uninitsWhenTrue.assign(uninits);
2346 if (setToNull) {
2347 resetBits(inits, uninits);
2348 }
2349 }
2350
2351 /** Merge (intersect) inits/uninits from WhenTrue/WhenFalse sets.
2352 */
2353 protected void merge() {
2354 inits.assign(initsWhenFalse.andSet(initsWhenTrue));
2355 uninits.assign(uninitsWhenFalse.andSet(uninitsWhenTrue));
2356 }
2357
2358 /* ************************************************************************
2359 * Visitor methods for statements and definitions
2360 *************************************************************************/
2361
2362 /** Analyze an expression. Make sure to set (un)inits rather than
2363 * (un)initsWhenTrue(WhenFalse) on exit.
2364 */
2365 void scanExpr(JCTree tree) {
2366 if (tree != null) {
2367 scan(tree);
2368 if (inits.isReset()) {
2369 merge();
2370 }
2371 }
2372 }
2373
2374 /** Analyze a list of expressions.
2375 */
2376 void scanExprs(List<? extends JCExpression> trees) {
2377 if (trees != null)
2378 for (List<? extends JCExpression> l = trees; l.nonEmpty(); l = l.tail)
2379 scanExpr(l.head);
2380 }
2381
2382 void scanPattern(JCTree tree) {
2383 scan(tree);
2384 }
2385
2386 /** Analyze a condition. Make sure to set (un)initsWhenTrue(WhenFalse)
2387 * rather than (un)inits on exit.
2388 */
2389 void scanCond(JCTree tree) {
2390 if (tree.type.isFalse()) {
2391 if (inits.isReset()) merge();
2392 initsWhenTrue.assign(inits);
2393 initsWhenTrue.inclRange(firstadr, nextadr);
2394 uninitsWhenTrue.assign(uninits);
2395 uninitsWhenTrue.inclRange(firstadr, nextadr);
2396 initsWhenFalse.assign(inits);
2397 uninitsWhenFalse.assign(uninits);
2398 } else if (tree.type.isTrue()) {
2399 if (inits.isReset()) merge();
2400 initsWhenFalse.assign(inits);
2401 initsWhenFalse.inclRange(firstadr, nextadr);
2402 uninitsWhenFalse.assign(uninits);
2403 uninitsWhenFalse.inclRange(firstadr, nextadr);
2404 initsWhenTrue.assign(inits);
2405 uninitsWhenTrue.assign(uninits);
2406 } else {
2407 scan(tree);
2408 if (!inits.isReset())
2409 split(tree.type != syms.unknownType);
2410 }
2411 if (tree.type != syms.unknownType) {
2412 resetBits(inits, uninits);
2413 }
2414 }
2415
2416 /* ------------ Visitor methods for various sorts of trees -------------*/
2417
2418 public void visitClassDef(JCClassDecl tree) {
2419 if (tree.sym == null) {
2420 return;
2421 }
2422
2423 Lint lintPrev = lint;
2424 lint = lint.augment(tree.sym);
2425 try {
2426 JCClassDecl classDefPrev = classDef;
2427 int firstadrPrev = firstadr;
2428 int nextadrPrev = nextadr;
2429 ListBuffer<PendingExit> pendingExitsPrev = pendingExits;
2430
2431 pendingExits = new ListBuffer<>();
2432 if (tree.name != names.empty) {
2433 firstadr = nextadr;
2434 }
2435 classDef = tree;
2436 try {
2437 // define all the static fields
2438 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
2439 if (l.head.hasTag(VARDEF)) {
2440 JCVariableDecl def = (JCVariableDecl)l.head;
2441 if ((def.mods.flags & STATIC) != 0) {
2442 VarSymbol sym = def.sym;
2443 if (trackable(sym)) {
2444 newVar(def);
2445 }
2446 }
2447 }
2448 }
2449
2450 // process all the static initializers
2451 forEachInitializer(tree, true, def -> {
2452 scan(def);
2453 clearPendingExits(false);
2454 });
2455
2456 // verify all static final fields got initialized
2457 for (int i = firstadr; i < nextadr; i++) {
2458 JCVariableDecl vardecl = vardecls[i];
2459 VarSymbol var = vardecl.sym;
2460 if (var.owner == classDef.sym && var.isStatic()) {
2461 checkInit(TreeInfo.diagnosticPositionFor(var, vardecl), var);
2462 }
2463 }
2464
2465 // define all the instance fields
2466 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
2467 if (l.head.hasTag(VARDEF)) {
2468 JCVariableDecl def = (JCVariableDecl)l.head;
2469 if ((def.mods.flags & STATIC) == 0) {
2470 VarSymbol sym = def.sym;
2471 if (trackable(sym)) {
2472 newVar(def);
2473 }
2474 }
2475 }
2476 }
2477
2478 // process all the methods
2479 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
2480 if (l.head.hasTag(METHODDEF)) {
2481 scan(l.head);
2482 }
2483 }
2484
2485 // process all the nested classes
2486 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
2487 if (l.head.hasTag(CLASSDEF)) {
2488 scan(l.head);
2489 }
2490 }
2491 } finally {
2492 pendingExits = pendingExitsPrev;
2493 nextadr = nextadrPrev;
2494 firstadr = firstadrPrev;
2495 classDef = classDefPrev;
2496 }
2497 } finally {
2498 lint = lintPrev;
2499 }
2500 }
2501
2502 public void visitMethodDef(JCMethodDecl tree) {
2503 if (tree.body == null) {
2504 return;
2505 }
2506
2507 /* MemberEnter can generate synthetic methods ignore them
2508 */
2509 if ((tree.sym.flags() & SYNTHETIC) != 0) {
2510 return;
2511 }
2512
2513 Lint lintPrev = lint;
2514 lint = lint.augment(tree.sym);
2515 try {
2516 final Bits initsPrev = new Bits(inits);
2517 final Bits uninitsPrev = new Bits(uninits);
2518 int nextadrPrev = nextadr;
2519 int firstadrPrev = firstadr;
2520 int returnadrPrev = returnadr;
2521
2522 Assert.check(pendingExits.isEmpty());
2523 boolean isConstructorPrev = isConstructor;
2524 try {
2525 isConstructor = TreeInfo.isConstructor(tree);
2526
2527 // We only track field initialization inside constructors
2528 if (!isConstructor) {
2529 firstadr = nextadr;
2530 }
2531
2532 // Mark all method parameters as DA
2533 for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
2534 JCVariableDecl def = l.head;
2535 scan(def);
2536 Assert.check((def.sym.flags() & PARAMETER) != 0, "Method parameter without PARAMETER flag");
2537 /* If we are executing the code from Gen, then there can be
2538 * synthetic or mandated variables, ignore them.
2539 */
2540 initParam(def);
2541 }
2542 if (isConstructor) {
2543 Set<VarSymbol> unsetFields = findUninitStrictFields();
2544 if (unsetFields != null && !unsetFields.isEmpty()) {
2545 unsetFieldsInfo.addUnsetFieldsInfo(classDef.sym, tree.body, unsetFields);
2546 }
2547 }
2548
2549 // else we are in an instance initializer block;
2550 // leave caught unchanged.
2551 scan(tree.body);
2552
2553 boolean isCompactOrGeneratedRecordConstructor = (tree.sym.flags() & Flags.COMPACT_RECORD_CONSTRUCTOR) != 0 ||
2554 (tree.sym.flags() & (GENERATEDCONSTR | RECORD)) == (GENERATEDCONSTR | RECORD);
2555 if (isConstructor) {
2556 boolean isSynthesized = (tree.sym.flags() &
2557 GENERATEDCONSTR) != 0;
2558 for (int i = firstadr; i < nextadr; i++) {
2559 JCVariableDecl vardecl = vardecls[i];
2560 VarSymbol var = vardecl.sym;
2561 if (var.owner == classDef.sym && !var.isStatic()) {
2562 // choose the diagnostic position based on whether
2563 // the ctor is default(synthesized) or not
2564 if (isSynthesized && !isCompactOrGeneratedRecordConstructor) {
2565 checkInit(TreeInfo.diagnosticPositionFor(var, vardecl),
2566 var, Errors.VarNotInitializedInDefaultConstructor(var));
2567 } else if (isCompactOrGeneratedRecordConstructor) {
2568 boolean isInstanceRecordField = var.enclClass().isRecord() &&
2569 (var.flags_field & (Flags.PRIVATE | Flags.FINAL | Flags.GENERATED_MEMBER | Flags.RECORD)) != 0 &&
2570 var.owner.kind == TYP;
2571 if (isInstanceRecordField) {
2572 boolean notInitialized = !inits.isMember(var.adr);
2573 if (notInitialized && uninits.isMember(var.adr) && tree.completesNormally) {
2574 /* this way we indicate Lower that it should generate an initialization for this field
2575 * in the compact constructor
2576 */
2577 var.flags_field |= UNINITIALIZED_FIELD;
2578 } else {
2579 checkInit(TreeInfo.diagEndPos(tree.body), var);
2580 }
2581 } else {
2582 checkInit(TreeInfo.diagnosticPositionFor(var, vardecl), var);
2583 }
2584 } else {
2585 checkInit(TreeInfo.diagEndPos(tree.body), var);
2586 }
2587 }
2588 }
2589 }
2590 clearPendingExits(true);
2591 } finally {
2592 inits.assign(initsPrev);
2593 uninits.assign(uninitsPrev);
2594 nextadr = nextadrPrev;
2595 firstadr = firstadrPrev;
2596 returnadr = returnadrPrev;
2597 isConstructor = isConstructorPrev;
2598 }
2599 } finally {
2600 lint = lintPrev;
2601 }
2602 }
2603
2604 Set<VarSymbol> findUninitStrictFields() {
2605 Set<VarSymbol> unsetFields = new LinkedHashSet<>();
2606 for (int i = uninits.nextBit(0); i >= 0; i = uninits.nextBit(i + 1)) {
2607 JCVariableDecl variableDecl = vardecls[i];
2608 if (variableDecl.sym.isStrict()) {
2609 unsetFields.add(variableDecl.sym);
2610 }
2611 }
2612 return unsetFields;
2613 }
2614
2615 private void clearPendingExits(boolean inMethod) {
2616 List<PendingExit> exits = pendingExits.toList();
2617 pendingExits = new ListBuffer<>();
2618 while (exits.nonEmpty()) {
2619 PendingExit exit = exits.head;
2620 exits = exits.tail;
2621 Assert.check((inMethod && exit.tree.hasTag(RETURN)) ||
2622 log.hasErrorOn(exit.tree.pos()),
2623 exit.tree);
2624 if (inMethod && isConstructor) {
2625 Assert.check(exit instanceof AssignPendingExit);
2626 inits.assign(((AssignPendingExit) exit).exit_inits);
2627 for (int i = firstadr; i < nextadr; i++) {
2628 checkInit(exit.tree.pos(), vardecls[i].sym);
2629 }
2630 }
2631 }
2632 }
2633 protected void initParam(JCVariableDecl def) {
2634 inits.incl(def.sym.adr);
2635 uninits.excl(def.sym.adr);
2636 }
2637
2638 public void visitVarDef(JCVariableDecl tree) {
2639 Lint lintPrev = lint;
2640 lint = lint.augment(tree.sym);
2641 try{
2642 boolean track = trackable(tree.sym);
2643 if (track && (tree.sym.owner.kind == MTH || tree.sym.owner.kind == VAR)) {
2644 newVar(tree);
2645 }
2646 if (tree.init != null) {
2647 scanExpr(tree.init);
2648 if (track) {
2649 letInit(tree.pos(), tree.sym);
2650 }
2651 }
2652 } finally {
2653 lint = lintPrev;
2654 }
2655 }
2656
2657 public void visitBlock(JCBlock tree) {
2658 int nextadrPrev = nextadr;
2659 scan(tree.stats);
2660 nextadr = nextadrPrev;
2661 }
2662
2663 public void visitDoLoop(JCDoWhileLoop tree) {
2664 ListBuffer<PendingExit> prevPendingExits = pendingExits;
2665 FlowKind prevFlowKind = flowKind;
2666 flowKind = FlowKind.NORMAL;
2667 final Bits initsSkip = new Bits(true);
2668 final Bits uninitsSkip = new Bits(true);
2669 pendingExits = new ListBuffer<>();
2670 int prevErrors = log.nerrors;
2671 do {
2672 final Bits uninitsEntry = new Bits(uninits);
2673 uninitsEntry.excludeFrom(nextadr);
2674 scan(tree.body);
2675 resolveContinues(tree);
2676 scanCond(tree.cond);
2677 if (!flowKind.isFinal()) {
2678 initsSkip.assign(initsWhenFalse);
2679 uninitsSkip.assign(uninitsWhenFalse);
2680 }
2681 if (log.nerrors != prevErrors ||
2682 flowKind.isFinal() ||
2683 new Bits(uninitsEntry).diffSet(uninitsWhenTrue).nextBit(firstadr)==-1)
2684 break;
2685 inits.assign(initsWhenTrue);
2686 uninits.assign(uninitsEntry.andSet(uninitsWhenTrue));
2687 flowKind = FlowKind.SPECULATIVE_LOOP;
2688 } while (true);
2689 flowKind = prevFlowKind;
2690 inits.assign(initsSkip);
2691 uninits.assign(uninitsSkip);
2692 resolveBreaks(tree, prevPendingExits);
2693 }
2694
2695 public void visitWhileLoop(JCWhileLoop tree) {
2696 ListBuffer<PendingExit> prevPendingExits = pendingExits;
2697 FlowKind prevFlowKind = flowKind;
2698 flowKind = FlowKind.NORMAL;
2699 final Bits initsSkip = new Bits(true);
2700 final Bits uninitsSkip = new Bits(true);
2701 pendingExits = new ListBuffer<>();
2702 int prevErrors = log.nerrors;
2703 final Bits uninitsEntry = new Bits(uninits);
2704 uninitsEntry.excludeFrom(nextadr);
2705 do {
2706 scanCond(tree.cond);
2707 if (!flowKind.isFinal()) {
2708 initsSkip.assign(initsWhenFalse) ;
2709 uninitsSkip.assign(uninitsWhenFalse);
2710 }
2711 inits.assign(initsWhenTrue);
2712 uninits.assign(uninitsWhenTrue);
2713 scan(tree.body);
2714 resolveContinues(tree);
2715 if (log.nerrors != prevErrors ||
2716 flowKind.isFinal() ||
2717 new Bits(uninitsEntry).diffSet(uninits).nextBit(firstadr) == -1) {
2718 break;
2719 }
2720 uninits.assign(uninitsEntry.andSet(uninits));
2721 flowKind = FlowKind.SPECULATIVE_LOOP;
2722 } while (true);
2723 flowKind = prevFlowKind;
2724 //a variable is DA/DU after the while statement, if it's DA/DU assuming the
2725 //branch is not taken AND if it's DA/DU before any break statement
2726 inits.assign(initsSkip);
2727 uninits.assign(uninitsSkip);
2728 resolveBreaks(tree, prevPendingExits);
2729 }
2730
2731 public void visitForLoop(JCForLoop tree) {
2732 ListBuffer<PendingExit> prevPendingExits = pendingExits;
2733 FlowKind prevFlowKind = flowKind;
2734 flowKind = FlowKind.NORMAL;
2735 int nextadrPrev = nextadr;
2736 scan(tree.init);
2737 final Bits initsSkip = new Bits(true);
2738 final Bits uninitsSkip = new Bits(true);
2739 pendingExits = new ListBuffer<>();
2740 int prevErrors = log.nerrors;
2741 do {
2742 final Bits uninitsEntry = new Bits(uninits);
2743 uninitsEntry.excludeFrom(nextadr);
2744 if (tree.cond != null) {
2745 scanCond(tree.cond);
2746 if (!flowKind.isFinal()) {
2747 initsSkip.assign(initsWhenFalse);
2748 uninitsSkip.assign(uninitsWhenFalse);
2749 }
2750 inits.assign(initsWhenTrue);
2751 uninits.assign(uninitsWhenTrue);
2752 } else if (!flowKind.isFinal()) {
2753 initsSkip.assign(inits);
2754 initsSkip.inclRange(firstadr, nextadr);
2755 uninitsSkip.assign(uninits);
2756 uninitsSkip.inclRange(firstadr, nextadr);
2757 }
2758 scan(tree.body);
2759 resolveContinues(tree);
2760 scan(tree.step);
2761 if (log.nerrors != prevErrors ||
2762 flowKind.isFinal() ||
2763 new Bits(uninitsEntry).diffSet(uninits).nextBit(firstadr) == -1)
2764 break;
2765 uninits.assign(uninitsEntry.andSet(uninits));
2766 flowKind = FlowKind.SPECULATIVE_LOOP;
2767 } while (true);
2768 flowKind = prevFlowKind;
2769 //a variable is DA/DU after a for loop, if it's DA/DU assuming the
2770 //branch is not taken AND if it's DA/DU before any break statement
2771 inits.assign(initsSkip);
2772 uninits.assign(uninitsSkip);
2773 resolveBreaks(tree, prevPendingExits);
2774 nextadr = nextadrPrev;
2775 }
2776
2777 public void visitForeachLoop(JCEnhancedForLoop tree) {
2778 visitVarDef(tree.var);
2779
2780 ListBuffer<PendingExit> prevPendingExits = pendingExits;
2781 FlowKind prevFlowKind = flowKind;
2782 flowKind = FlowKind.NORMAL;
2783 int nextadrPrev = nextadr;
2784 scan(tree.expr);
2785 final Bits initsStart = new Bits(inits);
2786 final Bits uninitsStart = new Bits(uninits);
2787
2788 letInit(tree.pos(), tree.var.sym);
2789 pendingExits = new ListBuffer<>();
2790 int prevErrors = log.nerrors;
2791 do {
2792 final Bits uninitsEntry = new Bits(uninits);
2793 uninitsEntry.excludeFrom(nextadr);
2794 scan(tree.body);
2795 resolveContinues(tree);
2796 if (log.nerrors != prevErrors ||
2797 flowKind.isFinal() ||
2798 new Bits(uninitsEntry).diffSet(uninits).nextBit(firstadr) == -1)
2799 break;
2800 uninits.assign(uninitsEntry.andSet(uninits));
2801 flowKind = FlowKind.SPECULATIVE_LOOP;
2802 } while (true);
2803 flowKind = prevFlowKind;
2804 inits.assign(initsStart);
2805 uninits.assign(uninitsStart.andSet(uninits));
2806 resolveBreaks(tree, prevPendingExits);
2807 nextadr = nextadrPrev;
2808 }
2809
2810 public void visitLabelled(JCLabeledStatement tree) {
2811 ListBuffer<PendingExit> prevPendingExits = pendingExits;
2812 pendingExits = new ListBuffer<>();
2813 scan(tree.body);
2814 resolveBreaks(tree, prevPendingExits);
2815 }
2816
2817 public void visitSwitch(JCSwitch tree) {
2818 handleSwitch(tree, tree.selector, tree.cases, tree.isExhaustive);
2819 }
2820
2821 public void visitSwitchExpression(JCSwitchExpression tree) {
2822 handleSwitch(tree, tree.selector, tree.cases, tree.isExhaustive);
2823 }
2824
2825 private void handleSwitch(JCTree tree, JCExpression selector,
2826 List<JCCase> cases, boolean isExhaustive) {
2827 ListBuffer<PendingExit> prevPendingExits = pendingExits;
2828 pendingExits = new ListBuffer<>();
2829 int nextadrPrev = nextadr;
2830 scanExpr(selector);
2831 final Bits initsSwitch = new Bits(inits);
2832 final Bits uninitsSwitch = new Bits(uninits);
2833 for (List<JCCase> l = cases; l.nonEmpty(); l = l.tail) {
2834 inits.assign(initsSwitch);
2835 uninits.assign(uninits.andSet(uninitsSwitch));
2836 JCCase c = l.head;
2837 for (JCCaseLabel pat : c.labels) {
2838 scanPattern(pat);
2839 }
2840 scan(c.guard);
2841 if (inits.isReset()) {
2842 inits.assign(initsWhenTrue);
2843 uninits.assign(uninitsWhenTrue);
2844 }
2845 scan(c.stats);
2846 if (c.completesNormally && c.caseKind == JCCase.RULE) {
2847 scanSyntheticBreak(make, tree);
2848 }
2849 addVars(c.stats, initsSwitch, uninitsSwitch);
2850 // Warn about fall-through if lint switch fallthrough enabled.
2851 }
2852 if (!isExhaustive) {
2853 if (tree.hasTag(SWITCH_EXPRESSION)) {
2854 markDead();
2855 } else if (tree.hasTag(SWITCH) && !TreeInfo.expectedExhaustive((JCSwitch) tree)) {
2856 inits.assign(initsSwitch);
2857 uninits.assign(uninits.andSet(uninitsSwitch));
2858 }
2859 }
2860 if (tree.hasTag(SWITCH_EXPRESSION)) {
2861 resolveYields(tree, prevPendingExits);
2862 } else {
2863 resolveBreaks(tree, prevPendingExits);
2864 }
2865 nextadr = nextadrPrev;
2866 }
2867 // where
2868 /** Add any variables defined in stats to inits and uninits. */
2869 private void addVars(List<JCStatement> stats, final Bits inits,
2870 final Bits uninits) {
2871 for (;stats.nonEmpty(); stats = stats.tail) {
2872 JCTree stat = stats.head;
2873 if (stat.hasTag(VARDEF)) {
2874 int adr = ((JCVariableDecl) stat).sym.adr;
2875 inits.excl(adr);
2876 uninits.incl(adr);
2877 }
2878 }
2879 }
2880
2881 public void visitTry(JCTry tree) {
2882 ListBuffer<JCVariableDecl> resourceVarDecls = new ListBuffer<>();
2883 final Bits uninitsTryPrev = new Bits(uninitsTry);
2884 ListBuffer<PendingExit> prevPendingExits = pendingExits;
2885 pendingExits = new ListBuffer<>();
2886 final Bits initsTry = new Bits(inits);
2887 uninitsTry.assign(uninits);
2888 for (JCTree resource : tree.resources) {
2889 if (resource instanceof JCVariableDecl variableDecl) {
2890 visitVarDef(variableDecl);
2891 unrefdResources.enter(variableDecl.sym);
2892 resourceVarDecls.append(variableDecl);
2893 } else if (resource instanceof JCExpression expression) {
2894 scanExpr(expression);
2895 } else {
2896 throw new AssertionError(tree); // parser error
2897 }
2898 }
2899 scan(tree.body);
2900 uninitsTry.andSet(uninits);
2901 final Bits initsEnd = new Bits(inits);
2902 final Bits uninitsEnd = new Bits(uninits);
2903 int nextadrCatch = nextadr;
2904
2905 if (!resourceVarDecls.isEmpty() &&
2906 lint.isEnabled(Lint.LintCategory.TRY)) {
2907 for (JCVariableDecl resVar : resourceVarDecls) {
2908 if (unrefdResources.includes(resVar.sym) && !resVar.sym.isUnnamedVariable()) {
2909 log.warning(resVar.pos(),
2910 LintWarnings.TryResourceNotReferenced(resVar.sym));
2911 unrefdResources.remove(resVar.sym);
2912 }
2913 }
2914 }
2915
2916 /* The analysis of each catch should be independent.
2917 * Each one should have the same initial values of inits and
2918 * uninits.
2919 */
2920 final Bits initsCatchPrev = new Bits(initsTry);
2921 final Bits uninitsCatchPrev = new Bits(uninitsTry);
2922
2923 for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
2924 JCVariableDecl param = l.head.param;
2925 inits.assign(initsCatchPrev);
2926 uninits.assign(uninitsCatchPrev);
2927 scan(param);
2928 /* If this is a TWR and we are executing the code from Gen,
2929 * then there can be synthetic variables, ignore them.
2930 */
2931 initParam(param);
2932 scan(l.head.body);
2933 initsEnd.andSet(inits);
2934 uninitsEnd.andSet(uninits);
2935 nextadr = nextadrCatch;
2936 }
2937 if (tree.finalizer != null) {
2938 inits.assign(initsTry);
2939 uninits.assign(uninitsTry);
2940 ListBuffer<PendingExit> exits = pendingExits;
2941 pendingExits = prevPendingExits;
2942 scan(tree.finalizer);
2943 if (!tree.finallyCanCompleteNormally) {
2944 // discard exits and exceptions from try and finally
2945 } else {
2946 uninits.andSet(uninitsEnd);
2947 // FIX: this doesn't preserve source order of exits in catch
2948 // versus finally!
2949 while (exits.nonEmpty()) {
2950 PendingExit exit = exits.next();
2951 if (exit instanceof AssignPendingExit assignPendingExit) {
2952 assignPendingExit.exit_inits.orSet(inits);
2953 assignPendingExit.exit_uninits.andSet(uninits);
2954 }
2955 pendingExits.append(exit);
2956 }
2957 inits.orSet(initsEnd);
2958 }
2959 } else {
2960 inits.assign(initsEnd);
2961 uninits.assign(uninitsEnd);
2962 ListBuffer<PendingExit> exits = pendingExits;
2963 pendingExits = prevPendingExits;
2964 while (exits.nonEmpty()) pendingExits.append(exits.next());
2965 }
2966 uninitsTry.andSet(uninitsTryPrev).andSet(uninits);
2967 }
2968
2969 public void visitConditional(JCConditional tree) {
2970 scanCond(tree.cond);
2971 final Bits initsBeforeElse = new Bits(initsWhenFalse);
2972 final Bits uninitsBeforeElse = new Bits(uninitsWhenFalse);
2973 inits.assign(initsWhenTrue);
2974 uninits.assign(uninitsWhenTrue);
2975 if (tree.truepart.type.hasTag(BOOLEAN) &&
2976 tree.falsepart.type.hasTag(BOOLEAN)) {
2977 // if b and c are boolean valued, then
2978 // v is (un)assigned after a?b:c when true iff
2979 // v is (un)assigned after b when true and
2980 // v is (un)assigned after c when true
2981 scanCond(tree.truepart);
2982 final Bits initsAfterThenWhenTrue = new Bits(initsWhenTrue);
2983 final Bits initsAfterThenWhenFalse = new Bits(initsWhenFalse);
2984 final Bits uninitsAfterThenWhenTrue = new Bits(uninitsWhenTrue);
2985 final Bits uninitsAfterThenWhenFalse = new Bits(uninitsWhenFalse);
2986 inits.assign(initsBeforeElse);
2987 uninits.assign(uninitsBeforeElse);
2988 scanCond(tree.falsepart);
2989 initsWhenTrue.andSet(initsAfterThenWhenTrue);
2990 initsWhenFalse.andSet(initsAfterThenWhenFalse);
2991 uninitsWhenTrue.andSet(uninitsAfterThenWhenTrue);
2992 uninitsWhenFalse.andSet(uninitsAfterThenWhenFalse);
2993 } else {
2994 scanExpr(tree.truepart);
2995 final Bits initsAfterThen = new Bits(inits);
2996 final Bits uninitsAfterThen = new Bits(uninits);
2997 inits.assign(initsBeforeElse);
2998 uninits.assign(uninitsBeforeElse);
2999 scanExpr(tree.falsepart);
3000 inits.andSet(initsAfterThen);
3001 uninits.andSet(uninitsAfterThen);
3002 }
3003 }
3004
3005 public void visitIf(JCIf tree) {
3006 scanCond(tree.cond);
3007 final Bits initsBeforeElse = new Bits(initsWhenFalse);
3008 final Bits uninitsBeforeElse = new Bits(uninitsWhenFalse);
3009 inits.assign(initsWhenTrue);
3010 uninits.assign(uninitsWhenTrue);
3011 scan(tree.thenpart);
3012 if (tree.elsepart != null) {
3013 final Bits initsAfterThen = new Bits(inits);
3014 final Bits uninitsAfterThen = new Bits(uninits);
3015 inits.assign(initsBeforeElse);
3016 uninits.assign(uninitsBeforeElse);
3017 scan(tree.elsepart);
3018 inits.andSet(initsAfterThen);
3019 uninits.andSet(uninitsAfterThen);
3020 } else {
3021 inits.andSet(initsBeforeElse);
3022 uninits.andSet(uninitsBeforeElse);
3023 }
3024 }
3025
3026 @Override
3027 public void visitBreak(JCBreak tree) {
3028 recordExit(new AssignPendingExit(tree, inits, uninits));
3029 }
3030
3031 @Override
3032 public void visitYield(JCYield tree) {
3033 JCSwitchExpression expr = (JCSwitchExpression) tree.target;
3034 if (expr != null && expr.type.hasTag(BOOLEAN)) {
3035 scanCond(tree.value);
3036 Bits initsAfterBreakWhenTrue = new Bits(initsWhenTrue);
3037 Bits initsAfterBreakWhenFalse = new Bits(initsWhenFalse);
3038 Bits uninitsAfterBreakWhenTrue = new Bits(uninitsWhenTrue);
3039 Bits uninitsAfterBreakWhenFalse = new Bits(uninitsWhenFalse);
3040 PendingExit exit = new PendingExit(tree) {
3041 @Override
3042 void resolveJump() {
3043 if (!inits.isReset()) {
3044 split(true);
3045 }
3046 initsWhenTrue.andSet(initsAfterBreakWhenTrue);
3047 initsWhenFalse.andSet(initsAfterBreakWhenFalse);
3048 uninitsWhenTrue.andSet(uninitsAfterBreakWhenTrue);
3049 uninitsWhenFalse.andSet(uninitsAfterBreakWhenFalse);
3050 }
3051 };
3052 merge();
3053 recordExit(exit);
3054 return ;
3055 } else {
3056 scanExpr(tree.value);
3057 recordExit(new AssignPendingExit(tree, inits, uninits));
3058 }
3059 }
3060
3061 @Override
3062 public void visitContinue(JCContinue tree) {
3063 recordExit(new AssignPendingExit(tree, inits, uninits));
3064 }
3065
3066 @Override
3067 public void visitReturn(JCReturn tree) {
3068 scanExpr(tree.expr);
3069 recordExit(new AssignPendingExit(tree, inits, uninits));
3070 }
3071
3072 public void visitThrow(JCThrow tree) {
3073 scanExpr(tree.expr);
3074 markDead();
3075 }
3076
3077 public void visitApply(JCMethodInvocation tree) {
3078 Name name = TreeInfo.name(tree.meth);
3079 // let's process early initializers
3080 if (name == names._super) {
3081 forEachInitializer(classDef, false, true, def -> {
3082 scan(def);
3083 clearPendingExits(false);
3084 });
3085 }
3086 scanExpr(tree.meth);
3087 scanExprs(tree.args);
3088
3089 // Handle superclass constructor invocations
3090 if (isConstructor) {
3091
3092 // If super(): at this point all initialization blocks will execute
3093
3094 if (name == names._super) {
3095 // strict fields should have been initialized at this point
3096 for (int i = firstadr; i < nextadr; i++) {
3097 JCVariableDecl vardecl = vardecls[i];
3098 VarSymbol var = vardecl.sym;
3099 boolean isInstanceRecordField = var.enclClass().isRecord() &&
3100 (var.flags_field & (Flags.PRIVATE | Flags.FINAL | Flags.GENERATED_MEMBER | Flags.RECORD)) != 0 &&
3101 var.owner.kind == TYP;
3102 if (var.owner == classDef.sym && !var.isStatic() && var.isStrict() && !isInstanceRecordField) {
3103 checkInit(TreeInfo.diagEndPos(tree), var, Errors.StrictFieldNotHaveBeenInitializedBeforeSuper(var));
3104 }
3105 }
3106 forEachInitializer(classDef, false, def -> {
3107 scan(def);
3108 clearPendingExits(false);
3109 });
3110 }
3111
3112 // If this(): at this point all final uninitialized fields will get initialized
3113 else if (name == names._this) {
3114 for (int address = firstadr; address < nextadr; address++) {
3115 VarSymbol sym = vardecls[address].sym;
3116 if (isFinalOrStrictUninitializedField(sym) && !sym.isStatic())
3117 letInit(tree.pos(), sym);
3118 }
3119 }
3120 }
3121 }
3122
3123 public void visitNewClass(JCNewClass tree) {
3124 scanExpr(tree.encl);
3125 scanExprs(tree.args);
3126 scan(tree.def);
3127 }
3128
3129 @Override
3130 public void visitLambda(JCLambda tree) {
3131 final Bits prevUninits = new Bits(uninits);
3132 final Bits prevUninitsTry = new Bits(uninitsTry);
3133 final Bits prevInits = new Bits(inits);
3134 int returnadrPrev = returnadr;
3135 int nextadrPrev = nextadr;
3136 ListBuffer<PendingExit> prevPending = pendingExits;
3137 try {
3138 // JLS 16.1.10: No rule allows V to be definitely unassigned before a lambda
3139 // body. This is by design: a variable that was definitely unassigned before the
3140 // lambda body may end up being assigned to later on, so we cannot conclude that
3141 // the variable will be unassigned when the body is executed.
3142 uninits.excludeFrom(firstadr);
3143 returnadr = nextadr;
3144 pendingExits = new ListBuffer<>();
3145 for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
3146 JCVariableDecl def = l.head;
3147 scan(def);
3148 inits.incl(def.sym.adr);
3149 uninits.excl(def.sym.adr);
3150 }
3151 if (tree.getBodyKind() == JCLambda.BodyKind.EXPRESSION) {
3152 scanExpr(tree.body);
3153 } else {
3154 scan(tree.body);
3155 }
3156 }
3157 finally {
3158 returnadr = returnadrPrev;
3159 uninits.assign(prevUninits);
3160 uninitsTry.assign(prevUninitsTry);
3161 inits.assign(prevInits);
3162 pendingExits = prevPending;
3163 nextadr = nextadrPrev;
3164 }
3165 }
3166
3167 public void visitNewArray(JCNewArray tree) {
3168 scanExprs(tree.dims);
3169 scanExprs(tree.elems);
3170 }
3171
3172 public void visitAssert(JCAssert tree) {
3173 final Bits initsExit = new Bits(inits);
3174 final Bits uninitsExit = new Bits(uninits);
3175 scanCond(tree.cond);
3176 uninitsExit.andSet(uninitsWhenTrue);
3177 if (tree.detail != null) {
3178 inits.assign(initsWhenFalse);
3179 uninits.assign(uninitsWhenFalse);
3180 scanExpr(tree.detail);
3181 }
3182 inits.assign(initsExit);
3183 uninits.assign(uninitsExit);
3184 }
3185
3186 public void visitAssign(JCAssign tree) {
3187 if (!TreeInfo.isIdentOrThisDotIdent(tree.lhs))
3188 scanExpr(tree.lhs);
3189 scanExpr(tree.rhs);
3190 letInit(tree.lhs, tree);
3191 }
3192
3193 // check fields accessed through this.<field> are definitely
3194 // assigned before reading their value
3195 public void visitSelect(JCFieldAccess tree) {
3196 super.visitSelect(tree);
3197 if (TreeInfo.isThisQualifier(tree.selected) &&
3198 tree.sym.kind == VAR) {
3199 checkInit(tree.pos(), (VarSymbol)tree.sym);
3200 }
3201 }
3202
3203 public void visitAssignop(JCAssignOp tree) {
3204 scanExpr(tree.lhs);
3205 scanExpr(tree.rhs);
3206 letInit(tree.lhs);
3207 }
3208
3209 public void visitUnary(JCUnary tree) {
3210 switch (tree.getTag()) {
3211 case NOT:
3212 scanCond(tree.arg);
3213 final Bits t = new Bits(initsWhenFalse);
3214 initsWhenFalse.assign(initsWhenTrue);
3215 initsWhenTrue.assign(t);
3216 t.assign(uninitsWhenFalse);
3217 uninitsWhenFalse.assign(uninitsWhenTrue);
3218 uninitsWhenTrue.assign(t);
3219 break;
3220 case PREINC: case POSTINC:
3221 case PREDEC: case POSTDEC:
3222 scanExpr(tree.arg);
3223 letInit(tree.arg);
3224 break;
3225 default:
3226 scanExpr(tree.arg);
3227 }
3228 }
3229
3230 public void visitBinary(JCBinary tree) {
3231 switch (tree.getTag()) {
3232 case AND:
3233 scanCond(tree.lhs);
3234 final Bits initsWhenFalseLeft = new Bits(initsWhenFalse);
3235 final Bits uninitsWhenFalseLeft = new Bits(uninitsWhenFalse);
3236 inits.assign(initsWhenTrue);
3237 uninits.assign(uninitsWhenTrue);
3238 scanCond(tree.rhs);
3239 initsWhenFalse.andSet(initsWhenFalseLeft);
3240 uninitsWhenFalse.andSet(uninitsWhenFalseLeft);
3241 break;
3242 case OR:
3243 scanCond(tree.lhs);
3244 final Bits initsWhenTrueLeft = new Bits(initsWhenTrue);
3245 final Bits uninitsWhenTrueLeft = new Bits(uninitsWhenTrue);
3246 inits.assign(initsWhenFalse);
3247 uninits.assign(uninitsWhenFalse);
3248 scanCond(tree.rhs);
3249 initsWhenTrue.andSet(initsWhenTrueLeft);
3250 uninitsWhenTrue.andSet(uninitsWhenTrueLeft);
3251 break;
3252 default:
3253 scanExpr(tree.lhs);
3254 scanExpr(tree.rhs);
3255 }
3256 }
3257
3258 public void visitIdent(JCIdent tree) {
3259 if (tree.sym.kind == VAR) {
3260 checkInit(tree.pos(), (VarSymbol)tree.sym);
3261 referenced(tree.sym);
3262 }
3263 }
3264
3265 @Override
3266 public void visitTypeTest(JCInstanceOf tree) {
3267 scanExpr(tree.expr);
3268 scan(tree.pattern);
3269 }
3270
3271 @Override
3272 public void visitBindingPattern(JCBindingPattern tree) {
3273 scan(tree.var);
3274 initParam(tree.var);
3275 }
3276
3277 void referenced(Symbol sym) {
3278 unrefdResources.remove(sym);
3279 }
3280
3281 public void visitAnnotatedType(JCAnnotatedType tree) {
3282 // annotations don't get scanned
3283 tree.underlyingType.accept(this);
3284 }
3285
3286 public void visitModuleDef(JCModuleDecl tree) {
3287 // Do nothing for modules
3288 }
3289
3290 /* ************************************************************************
3291 * main method
3292 *************************************************************************/
3293
3294 /** Perform definite assignment/unassignment analysis on a tree.
3295 */
3296 public void analyzeTree(Env<?> env, TreeMaker make) {
3297 analyzeTree(env, env.tree, make);
3298 }
3299
3300 public void analyzeTree(Env<?> env, JCTree tree, TreeMaker make) {
3301 try {
3302 startPos = tree.pos().getStartPosition();
3303
3304 if (vardecls == null)
3305 vardecls = new JCVariableDecl[32];
3306 else
3307 for (int i=0; i<vardecls.length; i++)
3308 vardecls[i] = null;
3309 firstadr = 0;
3310 nextadr = 0;
3311 Flow.this.make = make;
3312 pendingExits = new ListBuffer<>();
3313 this.classDef = null;
3314 unrefdResources = WriteableScope.create(env.enclClass.sym);
3315 scan(tree);
3316 } finally {
3317 // note that recursive invocations of this method fail hard
3318 startPos = -1;
3319 resetBits(inits, uninits, uninitsTry, initsWhenTrue,
3320 initsWhenFalse, uninitsWhenTrue, uninitsWhenFalse);
3321 if (vardecls != null) {
3322 for (int i=0; i<vardecls.length; i++)
3323 vardecls[i] = null;
3324 }
3325 firstadr = 0;
3326 nextadr = 0;
3327 Flow.this.make = null;
3328 pendingExits = null;
3329 this.classDef = null;
3330 unrefdResources = null;
3331 }
3332 }
3333 }
3334
3335 /**
3336 * This pass implements the last step of the dataflow analysis, namely
3337 * the effectively-final analysis check. This checks that every local variable
3338 * reference from a lambda body/local inner class is either final or effectively final.
3339 * Additional this also checks that every variable that is used as an operand to
3340 * try-with-resources is final or effectively final.
3341 * As effectively final variables are marked as such during DA/DU, this pass must run after
3342 * AssignAnalyzer.
3343 */
3344 class CaptureAnalyzer extends BaseAnalyzer {
3345
3346 JCTree currentTree; //local class or lambda
3347 WriteableScope declaredInsideGuard;
3348
3349 @Override
3350 void markDead() {
3351 //do nothing
3352 }
3353
3354 void checkEffectivelyFinal(DiagnosticPosition pos, VarSymbol sym) {
3355 if (currentTree != null &&
3356 sym.owner.kind == MTH &&
3357 sym.pos < getCurrentTreeStartPosition()) {
3358 switch (currentTree.getTag()) {
3359 case CLASSDEF:
3360 case CASE:
3361 case LAMBDA:
3362 if ((sym.flags() & (EFFECTIVELY_FINAL | FINAL)) == 0) {
3363 reportEffectivelyFinalError(pos, sym);
3364 }
3365 }
3366 }
3367 }
3368
3369 int getCurrentTreeStartPosition() {
3370 return currentTree instanceof JCCase cse ? cse.guard.getStartPosition()
3371 : currentTree.getStartPosition();
3372 }
3373
3374 void letInit(JCTree tree) {
3375 tree = TreeInfo.skipParens(tree);
3376 if (tree.hasTag(IDENT) || tree.hasTag(SELECT)) {
3377 Symbol sym = TreeInfo.symbol(tree);
3378 if (currentTree != null) {
3379 switch (currentTree.getTag()) {
3380 case CLASSDEF, LAMBDA -> {
3381 if (sym.kind == VAR &&
3382 sym.owner.kind == MTH &&
3383 ((VarSymbol)sym).pos < currentTree.getStartPosition()) {
3384 reportEffectivelyFinalError(tree, sym);
3385 }
3386 }
3387 case CASE -> {
3388 if (!declaredInsideGuard.includes(sym)) {
3389 log.error(tree.pos(), Errors.CannotAssignNotDeclaredGuard(sym));
3390 }
3391 }
3392 }
3393 }
3394 }
3395 }
3396
3397 void reportEffectivelyFinalError(DiagnosticPosition pos, Symbol sym) {
3398 Fragment subKey = switch (currentTree.getTag()) {
3399 case LAMBDA -> Fragments.Lambda;
3400 case CASE -> Fragments.Guard;
3401 case CLASSDEF -> Fragments.InnerCls;
3402 default -> throw new AssertionError("Unexpected tree kind: " + currentTree.getTag());
3403 };
3404 log.error(pos, Errors.CantRefNonEffectivelyFinalVar(sym, diags.fragment(subKey)));
3405 }
3406
3407 /* ***********************************************************************
3408 * Visitor methods for statements and definitions
3409 *************************************************************************/
3410
3411 /* ------------ Visitor methods for various sorts of trees -------------*/
3412
3413 public void visitClassDef(JCClassDecl tree) {
3414 JCTree prevTree = currentTree;
3415 try {
3416 currentTree = tree.sym.isDirectlyOrIndirectlyLocal() ? tree : null;
3417 super.visitClassDef(tree);
3418 } finally {
3419 currentTree = prevTree;
3420 }
3421 }
3422
3423 @Override
3424 public void visitLambda(JCLambda tree) {
3425 JCTree prevTree = currentTree;
3426 try {
3427 currentTree = tree;
3428 super.visitLambda(tree);
3429 } finally {
3430 currentTree = prevTree;
3431 }
3432 }
3433
3434 @Override
3435 public void visitBindingPattern(JCBindingPattern tree) {
3436 scan(tree.var);
3437 }
3438
3439 @Override
3440 public void visitCase(JCCase tree) {
3441 scan(tree.labels);
3442 if (tree.guard != null) {
3443 JCTree prevTree = currentTree;
3444 WriteableScope prevDeclaredInsideGuard = declaredInsideGuard;
3445 try {
3446 currentTree = tree;
3447 declaredInsideGuard = WriteableScope.create(attrEnv.enclClass.sym);
3448 scan(tree.guard);
3449 } finally {
3450 currentTree = prevTree;
3451 declaredInsideGuard = prevDeclaredInsideGuard;
3452 }
3453 }
3454 scan(tree.stats);
3455 }
3456
3457 @Override
3458 public void visitRecordPattern(JCRecordPattern tree) {
3459 scan(tree.deconstructor);
3460 scan(tree.nested);
3461 }
3462
3463 @Override
3464 public void visitIdent(JCIdent tree) {
3465 if (tree.sym.kind == VAR) {
3466 checkEffectivelyFinal(tree, (VarSymbol)tree.sym);
3467 }
3468 }
3469
3470 public void visitAssign(JCAssign tree) {
3471 JCTree lhs = TreeInfo.skipParens(tree.lhs);
3472 if (!(lhs instanceof JCIdent)) {
3473 scan(lhs);
3474 }
3475 scan(tree.rhs);
3476 letInit(lhs);
3477 }
3478
3479 public void visitAssignop(JCAssignOp tree) {
3480 scan(tree.lhs);
3481 scan(tree.rhs);
3482 letInit(tree.lhs);
3483 }
3484
3485 public void visitUnary(JCUnary tree) {
3486 switch (tree.getTag()) {
3487 case PREINC: case POSTINC:
3488 case PREDEC: case POSTDEC:
3489 scan(tree.arg);
3490 letInit(tree.arg);
3491 break;
3492 default:
3493 scan(tree.arg);
3494 }
3495 }
3496
3497 public void visitTry(JCTry tree) {
3498 for (JCTree resource : tree.resources) {
3499 if (!resource.hasTag(VARDEF)) {
3500 Symbol var = TreeInfo.symbol(resource);
3501 if (var != null && (var.flags() & (FINAL | EFFECTIVELY_FINAL)) == 0) {
3502 log.error(resource.pos(), Errors.TryWithResourcesExprEffectivelyFinalVar(var));
3503 }
3504 }
3505 }
3506 super.visitTry(tree);
3507 }
3508
3509 @Override
3510 public void visitVarDef(JCVariableDecl tree) {
3511 if (declaredInsideGuard != null) {
3512 declaredInsideGuard.enter(tree.sym);
3513 }
3514 super.visitVarDef(tree);
3515 }
3516
3517 @Override
3518 public void visitYield(JCYield tree) {
3519 scan(tree.value);
3520 }
3521
3522 public void visitModuleDef(JCModuleDecl tree) {
3523 // Do nothing for modules
3524 }
3525
3526 /* ************************************************************************
3527 * main method
3528 *************************************************************************/
3529
3530 /** Perform definite assignment/unassignment analysis on a tree.
3531 */
3532 public void analyzeTree(Env<AttrContext> env, TreeMaker make) {
3533 analyzeTree(env, env.tree, make);
3534 }
3535 public void analyzeTree(Env<AttrContext> env, JCTree tree, TreeMaker make) {
3536 try {
3537 attrEnv = env;
3538 Flow.this.make = make;
3539 pendingExits = new ListBuffer<>();
3540 scan(tree);
3541 } finally {
3542 pendingExits = null;
3543 Flow.this.make = null;
3544 }
3545 }
3546 }
3547
3548 enum Liveness {
3549 ALIVE {
3550 @Override
3551 public Liveness or(Liveness other) {
3552 return this;
3553 }
3554 @Override
3555 public Liveness and(Liveness other) {
3556 return other;
3557 }
3558 },
3559 DEAD {
3560 @Override
3561 public Liveness or(Liveness other) {
3562 return other;
3563 }
3564 @Override
3565 public Liveness and(Liveness other) {
3566 return this;
3567 }
3568 },
3569 RECOVERY {
3570 @Override
3571 public Liveness or(Liveness other) {
3572 if (other == ALIVE) {
3573 return ALIVE;
3574 } else {
3575 return this;
3576 }
3577 }
3578 @Override
3579 public Liveness and(Liveness other) {
3580 if (other == DEAD) {
3581 return DEAD;
3582 } else {
3583 return this;
3584 }
3585 }
3586 };
3587
3588 public abstract Liveness or(Liveness other);
3589 public abstract Liveness and(Liveness other);
3590 public Liveness or(boolean value) {
3591 return or(from(value));
3592 }
3593 public Liveness and(boolean value) {
3594 return and(from(value));
3595 }
3596 public static Liveness from(boolean value) {
3597 return value ? ALIVE : DEAD;
3598 }
3599 }
3600
3601 sealed interface PatternDescription { }
3602 public PatternDescription makePatternDescription(Type selectorType, JCPattern pattern) {
3603 if (pattern instanceof JCBindingPattern binding) {
3604 Type type = !selectorType.isPrimitive() && types.isSubtype(selectorType, binding.type)
3605 ? selectorType : binding.type;
3606 return new BindingPattern(type);
3607 } else if (pattern instanceof JCRecordPattern record) {
3608 Type[] componentTypes;
3609
3610 if (!record.type.isErroneous()) {
3611 componentTypes = ((ClassSymbol) record.type.tsym).getRecordComponents()
3612 .map(r -> types.memberType(record.type, r))
3613 .toArray(s -> new Type[s]);
3614 }
3615 else {
3616 componentTypes = record.nested.map(t -> types.createErrorType(t.type)).toArray(s -> new Type[s]);;
3617 }
3618
3619 PatternDescription[] nestedDescriptions =
3620 new PatternDescription[record.nested.size()];
3621 int i = 0;
3622 for (List<JCPattern> it = record.nested;
3623 it.nonEmpty();
3624 it = it.tail, i++) {
3625 Type componentType = i < componentTypes.length ? componentTypes[i]
3626 : syms.errType;
3627 nestedDescriptions[i] = makePatternDescription(types.erasure(componentType), it.head);
3628 }
3629 return new RecordPattern(record.type, componentTypes, nestedDescriptions);
3630 } else if (pattern instanceof JCAnyPattern) {
3631 return new BindingPattern(selectorType);
3632 } else {
3633 throw Assert.error();
3634 }
3635 }
3636 record BindingPattern(Type type) implements PatternDescription {
3637 @Override
3638 public int hashCode() {
3639 return type.tsym.hashCode();
3640 }
3641 @Override
3642 public boolean equals(Object o) {
3643 return o instanceof BindingPattern other &&
3644 type.tsym == other.type.tsym;
3645 }
3646 @Override
3647 public String toString() {
3648 return type.tsym + " _";
3649 }
3650 }
3651 record RecordPattern(Type recordType, int _hashCode, Type[] fullComponentTypes, PatternDescription... nested) implements PatternDescription {
3652
3653 public RecordPattern(Type recordType, Type[] fullComponentTypes, PatternDescription[] nested) {
3654 this(recordType, hashCode(-1, recordType, nested), fullComponentTypes, nested);
3655 }
3656
3657 @Override
3658 public int hashCode() {
3659 return _hashCode;
3660 }
3661
3662 @Override
3663 public boolean equals(Object o) {
3664 return o instanceof RecordPattern other &&
3665 recordType.tsym == other.recordType.tsym &&
3666 Arrays.equals(nested, other.nested);
3667 }
3668
3669 public int hashCode(int excludeComponent) {
3670 return hashCode(excludeComponent, recordType, nested);
3671 }
3672
3673 public static int hashCode(int excludeComponent, Type recordType, PatternDescription... nested) {
3674 int hash = 5;
3675 hash = 41 * hash + recordType.tsym.hashCode();
3676 for (int i = 0; i < nested.length; i++) {
3677 if (i != excludeComponent) {
3678 hash = 41 * hash + nested[i].hashCode();
3679 }
3680 }
3681 return hash;
3682 }
3683 @Override
3684 public String toString() {
3685 return recordType.tsym + "(" + Arrays.stream(nested)
3686 .map(pd -> pd.toString())
3687 .collect(Collectors.joining(", ")) + ")";
3688 }
3689 }
3690 }