1 /*
2 * Copyright (c) 1999, 2009, 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.HashMap;
31
32 import com.sun.tools.javac.code.*;
33 import com.sun.tools.javac.tree.*;
34 import com.sun.tools.javac.util.*;
35 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
36
37 import com.sun.tools.javac.code.Symbol.*;
38 import com.sun.tools.javac.tree.JCTree.*;
39
40 import static com.sun.tools.javac.code.Flags.*;
41 import static com.sun.tools.javac.code.Kinds.*;
42 import static com.sun.tools.javac.code.TypeTags.*;
43
44 /** This pass implements dataflow analysis for Java programs.
45 * Liveness analysis checks that every statement is reachable.
46 * Exception analysis ensures that every checked exception that is
47 * thrown is declared or caught. Definite assignment analysis
48 * ensures that each variable is assigned when used. Definite
49 * unassignment analysis ensures that no final variable is assigned
50 * more than once.
51 *
52 * <p>The second edition of the JLS has a number of problems in the
53 * specification of these flow analysis problems. This implementation
54 * attempts to address those issues.
55 *
56 * <p>First, there is no accommodation for a finally clause that cannot
57 * complete normally. For liveness analysis, an intervening finally
58 * clause can cause a break, continue, or return not to reach its
59 * target. For exception analysis, an intervening finally clause can
60 * cause any exception to be "caught". For DA/DU analysis, the finally
61 * clause can prevent a transfer of control from propagating DA/DU
62 * state to the target. In addition, code in the finally clause can
63 * affect the DA/DU status of variables.
64 *
65 * <p>For try statements, we introduce the idea of a variable being
66 * definitely unassigned "everywhere" in a block. A variable V is
67 * "unassigned everywhere" in a block iff it is unassigned at the
68 * beginning of the block and there is no reachable assignment to V
69 * in the block. An assignment V=e is reachable iff V is not DA
70 * after e. Then we can say that V is DU at the beginning of the
71 * catch block iff V is DU everywhere in the try block. Similarly, V
72 * is DU at the beginning of the finally block iff V is DU everywhere
73 * in the try block and in every catch block. Specifically, the
74 * following bullet is added to 16.2.2
75 * <pre>
76 * V is <em>unassigned everywhere</em> in a block if it is
77 * unassigned before the block and there is no reachable
78 * assignment to V within the block.
79 * </pre>
80 * <p>In 16.2.15, the third bullet (and all of its sub-bullets) for all
81 * try blocks is changed to
82 * <pre>
83 * V is definitely unassigned before a catch block iff V is
84 * definitely unassigned everywhere in the try block.
85 * </pre>
86 * <p>The last bullet (and all of its sub-bullets) for try blocks that
87 * have a finally block is changed to
88 * <pre>
89 * V is definitely unassigned before the finally block iff
90 * V is definitely unassigned everywhere in the try block
91 * and everywhere in each catch block of the try statement.
92 * </pre>
93 * <p>In addition,
94 * <pre>
95 * V is definitely assigned at the end of a constructor iff
96 * V is definitely assigned after the block that is the body
97 * of the constructor and V is definitely assigned at every
98 * return that can return from the constructor.
99 * </pre>
100 * <p>In addition, each continue statement with the loop as its target
101 * is treated as a jump to the end of the loop body, and "intervening"
102 * finally clauses are treated as follows: V is DA "due to the
103 * continue" iff V is DA before the continue statement or V is DA at
104 * the end of any intervening finally block. V is DU "due to the
105 * continue" iff any intervening finally cannot complete normally or V
106 * is DU at the end of every intervening finally block. This "due to
107 * the continue" concept is then used in the spec for the loops.
108 *
109 * <p>Similarly, break statements must consider intervening finally
110 * blocks. For liveness analysis, a break statement for which any
111 * intervening finally cannot complete normally is not considered to
112 * cause the target statement to be able to complete normally. Then
113 * we say V is DA "due to the break" iff V is DA before the break or
114 * V is DA at the end of any intervening finally block. V is DU "due
115 * to the break" iff any intervening finally cannot complete normally
116 * or V is DU at the break and at the end of every intervening
117 * finally block. (I suspect this latter condition can be
118 * simplified.) This "due to the break" is then used in the spec for
119 * all statements that can be "broken".
120 *
121 * <p>The return statement is treated similarly. V is DA "due to a
122 * return statement" iff V is DA before the return statement or V is
123 * DA at the end of any intervening finally block. Note that we
124 * don't have to worry about the return expression because this
125 * concept is only used for construcrors.
126 *
127 * <p>There is no spec in JLS2 for when a variable is definitely
128 * assigned at the end of a constructor, which is needed for final
129 * fields (8.3.1.2). We implement the rule that V is DA at the end
130 * of the constructor iff it is DA and the end of the body of the
131 * constructor and V is DA "due to" every return of the constructor.
132 *
133 * <p>Intervening finally blocks similarly affect exception analysis. An
134 * intervening finally that cannot complete normally allows us to ignore
135 * an otherwise uncaught exception.
136 *
137 * <p>To implement the semantics of intervening finally clauses, all
138 * nonlocal transfers (break, continue, return, throw, method call that
139 * can throw a checked exception, and a constructor invocation that can
140 * thrown a checked exception) are recorded in a queue, and removed
141 * from the queue when we complete processing the target of the
142 * nonlocal transfer. This allows us to modify the queue in accordance
143 * with the above rules when we encounter a finally clause. The only
144 * exception to this [no pun intended] is that checked exceptions that
145 * are known to be caught or declared to be caught in the enclosing
146 * method are not recorded in the queue, but instead are recorded in a
147 * global variable "Set<Type> thrown" that records the type of all
148 * exceptions that can be thrown.
149 *
150 * <p>Other minor issues the treatment of members of other classes
151 * (always considered DA except that within an anonymous class
152 * constructor, where DA status from the enclosing scope is
153 * preserved), treatment of the case expression (V is DA before the
154 * case expression iff V is DA after the switch expression),
155 * treatment of variables declared in a switch block (the implied
156 * DA/DU status after the switch expression is DU and not DA for
157 * variables defined in a switch block), the treatment of boolean ?:
158 * expressions (The JLS rules only handle b and c non-boolean; the
159 * new rule is that if b and c are boolean valued, then V is
160 * (un)assigned after a?b:c when true/false iff V is (un)assigned
161 * after b when true/false and V is (un)assigned after c when
162 * true/false).
163 *
164 * <p>There is the remaining question of what syntactic forms constitute a
165 * reference to a variable. It is conventional to allow this.x on the
166 * left-hand-side to initialize a final instance field named x, yet
167 * this.x isn't considered a "use" when appearing on a right-hand-side
168 * in most implementations. Should parentheses affect what is
169 * considered a variable reference? The simplest rule would be to
170 * allow unqualified forms only, parentheses optional, and phase out
171 * support for assigning to a final field via this.x.
172 *
173 * <p><b>This is NOT part of any supported API.
174 * If you write code that depends on this, you do so at your own risk.
175 * This code and its internal interfaces are subject to change or
176 * deletion without notice.</b>
177 */
178 public class Flow extends TreeScanner {
179 protected static final Context.Key<Flow> flowKey =
180 new Context.Key<Flow>();
181
182 private final Names names;
183 private final Log log;
184 private final Symtab syms;
185 private final Types types;
186 private final Check chk;
187 private TreeMaker make;
188 private Lint lint;
189 private final boolean allowRethrowAnalysis;
190
191 public static Flow instance(Context context) {
192 Flow instance = context.get(flowKey);
193 if (instance == null)
194 instance = new Flow(context);
195 return instance;
196 }
197
198 protected Flow(Context context) {
199 context.put(flowKey, this);
200 names = Names.instance(context);
201 log = Log.instance(context);
202 syms = Symtab.instance(context);
203 types = Types.instance(context);
204 chk = Check.instance(context);
205 lint = Lint.instance(context);
206 Source source = Source.instance(context);
207 allowRethrowAnalysis = source.allowMulticatch();
208 }
209
210 /** A flag that indicates whether the last statement could
211 * complete normally.
212 */
213 private boolean alive;
214
215 /** The set of definitely assigned variables.
216 */
217 Bits inits;
218
219 /** The set of definitely unassigned variables.
220 */
221 Bits uninits;
222
223 HashMap<Symbol, List<Type>> multicatchTypes;
224
225 /** The set of variables that are definitely unassigned everywhere
226 * in current try block. This variable is maintained lazily; it is
227 * updated only when something gets removed from uninits,
228 * typically by being assigned in reachable code. To obtain the
229 * correct set of variables which are definitely unassigned
230 * anywhere in current try block, intersect uninitsTry and
231 * uninits.
232 */
233 Bits uninitsTry;
234
235 /** When analyzing a condition, inits and uninits are null.
236 * Instead we have:
237 */
238 Bits initsWhenTrue;
239 Bits initsWhenFalse;
240 Bits uninitsWhenTrue;
241 Bits uninitsWhenFalse;
242
243 /** A mapping from addresses to variable symbols.
244 */
245 VarSymbol[] vars;
246
247 /** The current class being defined.
248 */
249 JCClassDecl classDef;
250
251 /** The first variable sequence number in this class definition.
252 */
253 int firstadr;
254
255 /** The next available variable sequence number.
256 */
257 int nextadr;
258
259 /** The list of possibly thrown declarable exceptions.
260 */
261 List<Type> thrown;
262
263 /** The list of exceptions that are either caught or declared to be
264 * thrown.
265 */
266 List<Type> caught;
267
268 /** The list of unreferenced automatic resources.
269 */
270 List<Symbol> unrefdResources;
271
272 /** Set when processing a loop body the second time for DU analysis. */
273 boolean loopPassTwo = false;
274
275 /*-------------------- Environments ----------------------*/
276
277 /** A pending exit. These are the statements return, break, and
278 * continue. In addition, exception-throwing expressions or
279 * statements are put here when not known to be caught. This
280 * will typically result in an error unless it is within a
281 * try-finally whose finally block cannot complete normally.
282 */
283 static class PendingExit {
284 JCTree tree;
285 Bits inits;
286 Bits uninits;
287 Type thrown;
288 PendingExit(JCTree tree, Bits inits, Bits uninits) {
289 this.tree = tree;
290 this.inits = inits.dup();
291 this.uninits = uninits.dup();
292 }
293 PendingExit(JCTree tree, Type thrown) {
294 this.tree = tree;
295 this.thrown = thrown;
296 }
297 }
298
299 /** The currently pending exits that go from current inner blocks
300 * to an enclosing block, in source order.
301 */
302 ListBuffer<PendingExit> pendingExits;
303
304 /*-------------------- Exceptions ----------------------*/
305
306 /** Complain that pending exceptions are not caught.
307 */
308 void errorUncaught() {
309 for (PendingExit exit = pendingExits.next();
310 exit != null;
311 exit = pendingExits.next()) {
312 boolean synthetic = classDef != null &&
313 classDef.pos == exit.tree.pos;
314 log.error(exit.tree.pos(),
315 synthetic
316 ? "unreported.exception.default.constructor"
317 : "unreported.exception.need.to.catch.or.throw",
318 exit.thrown);
319 }
320 }
321
322 /** Record that exception is potentially thrown and check that it
323 * is caught.
324 */
325 void markThrown(JCTree tree, Type exc) {
326 if (!chk.isUnchecked(tree.pos(), exc)) {
327 if (!chk.isHandled(exc, caught))
328 pendingExits.append(new PendingExit(tree, exc));
329 thrown = chk.incl(exc, thrown);
330 }
331 }
332
333 /*-------------- Processing variables ----------------------*/
334
335 /** Do we need to track init/uninit state of this symbol?
336 * I.e. is symbol either a local or a blank final variable?
337 */
338 boolean trackable(VarSymbol sym) {
339 return
340 (sym.owner.kind == MTH ||
341 ((sym.flags() & (FINAL | HASINIT | PARAMETER)) == FINAL &&
342 classDef.sym.isEnclosedBy((ClassSymbol)sym.owner)));
343 }
344
345 /** Initialize new trackable variable by setting its address field
346 * to the next available sequence number and entering it under that
347 * index into the vars array.
348 */
349 void newVar(VarSymbol sym) {
350 if (nextadr == vars.length) {
351 VarSymbol[] newvars = new VarSymbol[nextadr * 2];
352 System.arraycopy(vars, 0, newvars, 0, nextadr);
353 vars = newvars;
354 }
355 sym.adr = nextadr;
356 vars[nextadr] = sym;
357 inits.excl(nextadr);
358 uninits.incl(nextadr);
359 nextadr++;
360 }
361
362 /** Record an initialization of a trackable variable.
363 */
364 void letInit(DiagnosticPosition pos, VarSymbol sym) {
365 if (sym.adr >= firstadr && trackable(sym)) {
366 if ((sym.flags() & FINAL) != 0) {
367 if ((sym.flags() & PARAMETER) != 0) {
368 if ((sym.flags() & DISJOINT) != 0) { //multi-catch parameter
369 log.error(pos, "multicatch.parameter.may.not.be.assigned",
370 sym);
371 }
372 else {
373 log.error(pos, "final.parameter.may.not.be.assigned",
374 sym);
375 }
376 } else if (!uninits.isMember(sym.adr)) {
377 log.error(pos,
378 loopPassTwo
379 ? "var.might.be.assigned.in.loop"
380 : "var.might.already.be.assigned",
381 sym);
382 } else if (!inits.isMember(sym.adr)) {
383 // reachable assignment
384 uninits.excl(sym.adr);
385 uninitsTry.excl(sym.adr);
386 } else {
387 //log.rawWarning(pos, "unreachable assignment");//DEBUG
388 uninits.excl(sym.adr);
389 }
390 }
391 inits.incl(sym.adr);
392 } else if ((sym.flags() & FINAL) != 0) {
393 log.error(pos, "var.might.already.be.assigned", sym);
394 }
395 }
396
397 /** If tree is either a simple name or of the form this.name or
398 * C.this.name, and tree represents a trackable variable,
399 * record an initialization of the variable.
400 */
401 void letInit(JCTree tree) {
402 tree = TreeInfo.skipParens(tree);
403 if (tree.getTag() == JCTree.IDENT || tree.getTag() == JCTree.SELECT) {
404 Symbol sym = TreeInfo.symbol(tree);
405 letInit(tree.pos(), (VarSymbol)sym);
406 }
407 }
408
409 /** Check that trackable variable is initialized.
410 */
411 void checkInit(DiagnosticPosition pos, VarSymbol sym) {
412 if ((sym.adr >= firstadr || sym.owner.kind != TYP) &&
413 trackable(sym) &&
414 !inits.isMember(sym.adr)) {
415 log.error(pos, "var.might.not.have.been.initialized",
416 sym);
417 inits.incl(sym.adr);
418 }
419 }
420
421 /*-------------------- Handling jumps ----------------------*/
422
423 /** Record an outward transfer of control. */
424 void recordExit(JCTree tree) {
425 pendingExits.append(new PendingExit(tree, inits, uninits));
426 markDead();
427 }
428
429 /** Resolve all breaks of this statement. */
430 boolean resolveBreaks(JCTree tree,
431 ListBuffer<PendingExit> oldPendingExits) {
432 boolean result = false;
433 List<PendingExit> exits = pendingExits.toList();
434 pendingExits = oldPendingExits;
435 for (; exits.nonEmpty(); exits = exits.tail) {
436 PendingExit exit = exits.head;
437 if (exit.tree.getTag() == JCTree.BREAK &&
438 ((JCBreak) exit.tree).target == tree) {
439 inits.andSet(exit.inits);
440 uninits.andSet(exit.uninits);
441 result = true;
442 } else {
443 pendingExits.append(exit);
444 }
445 }
446 return result;
447 }
448
449 /** Resolve all continues of this statement. */
450 boolean resolveContinues(JCTree tree) {
451 boolean result = false;
452 List<PendingExit> exits = pendingExits.toList();
453 pendingExits = new ListBuffer<PendingExit>();
454 for (; exits.nonEmpty(); exits = exits.tail) {
455 PendingExit exit = exits.head;
456 if (exit.tree.getTag() == JCTree.CONTINUE &&
457 ((JCContinue) exit.tree).target == tree) {
458 inits.andSet(exit.inits);
459 uninits.andSet(exit.uninits);
460 result = true;
461 } else {
462 pendingExits.append(exit);
463 }
464 }
465 return result;
466 }
467
468 /** Record that statement is unreachable.
469 */
470 void markDead() {
471 inits.inclRange(firstadr, nextadr);
472 uninits.inclRange(firstadr, nextadr);
473 alive = false;
474 }
475
476 /** Split (duplicate) inits/uninits into WhenTrue/WhenFalse sets
477 */
478 void split() {
479 initsWhenFalse = inits.dup();
480 uninitsWhenFalse = uninits.dup();
481 initsWhenTrue = inits;
482 uninitsWhenTrue = uninits;
483 inits = uninits = null;
484 }
485
486 /** Merge (intersect) inits/uninits from WhenTrue/WhenFalse sets.
487 */
488 void merge() {
489 inits = initsWhenFalse.andSet(initsWhenTrue);
490 uninits = uninitsWhenFalse.andSet(uninitsWhenTrue);
491 }
492
493 /* ************************************************************************
494 * Visitor methods for statements and definitions
495 *************************************************************************/
496
497 /** Analyze a definition.
498 */
499 void scanDef(JCTree tree) {
500 scanStat(tree);
501 if (tree != null && tree.getTag() == JCTree.BLOCK && !alive) {
502 log.error(tree.pos(),
503 "initializer.must.be.able.to.complete.normally");
504 }
505 }
506
507 /** Analyze a statement. Check that statement is reachable.
508 */
509 void scanStat(JCTree tree) {
510 if (!alive && tree != null) {
511 log.error(tree.pos(), "unreachable.stmt");
512 if (tree.getTag() != JCTree.SKIP) alive = true;
513 }
514 scan(tree);
515 }
516
517 /** Analyze list of statements.
518 */
519 void scanStats(List<? extends JCStatement> trees) {
520 if (trees != null)
521 for (List<? extends JCStatement> l = trees; l.nonEmpty(); l = l.tail)
522 scanStat(l.head);
523 }
524
525 /** Analyze an expression. Make sure to set (un)inits rather than
526 * (un)initsWhenTrue(WhenFalse) on exit.
527 */
528 void scanExpr(JCTree tree) {
529 if (tree != null) {
530 scan(tree);
531 if (inits == null) merge();
532 }
533 }
534
535 /** Analyze a list of expressions.
536 */
537 void scanExprs(List<? extends JCExpression> trees) {
538 if (trees != null)
539 for (List<? extends JCExpression> l = trees; l.nonEmpty(); l = l.tail)
540 scanExpr(l.head);
541 }
542
543 /** Analyze a condition. Make sure to set (un)initsWhenTrue(WhenFalse)
544 * rather than (un)inits on exit.
545 */
546 void scanCond(JCTree tree) {
547 if (tree.type.isFalse()) {
548 if (inits == null) merge();
549 initsWhenTrue = inits.dup();
550 initsWhenTrue.inclRange(firstadr, nextadr);
551 uninitsWhenTrue = uninits.dup();
552 uninitsWhenTrue.inclRange(firstadr, nextadr);
553 initsWhenFalse = inits;
554 uninitsWhenFalse = uninits;
555 } else if (tree.type.isTrue()) {
556 if (inits == null) merge();
557 initsWhenFalse = inits.dup();
558 initsWhenFalse.inclRange(firstadr, nextadr);
559 uninitsWhenFalse = uninits.dup();
560 uninitsWhenFalse.inclRange(firstadr, nextadr);
561 initsWhenTrue = inits;
562 uninitsWhenTrue = uninits;
563 } else {
564 scan(tree);
565 if (inits != null) split();
566 }
567 inits = uninits = null;
568 }
569
570 /* ------------ Visitor methods for various sorts of trees -------------*/
571
572 public void visitClassDef(JCClassDecl tree) {
573 if (tree.sym == null) return;
574
575 JCClassDecl classDefPrev = classDef;
576 List<Type> thrownPrev = thrown;
577 List<Type> caughtPrev = caught;
578 boolean alivePrev = alive;
579 int firstadrPrev = firstadr;
580 int nextadrPrev = nextadr;
581 ListBuffer<PendingExit> pendingExitsPrev = pendingExits;
582 Lint lintPrev = lint;
583
584 pendingExits = new ListBuffer<PendingExit>();
585 if (tree.name != names.empty) {
586 caught = List.nil();
587 firstadr = nextadr;
588 }
589 classDef = tree;
590 thrown = List.nil();
591 lint = lint.augment(tree.sym.attributes_field);
592
593 try {
594 // define all the static fields
595 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
596 if (l.head.getTag() == JCTree.VARDEF) {
597 JCVariableDecl def = (JCVariableDecl)l.head;
598 if ((def.mods.flags & STATIC) != 0) {
599 VarSymbol sym = def.sym;
600 if (trackable(sym))
601 newVar(sym);
602 }
603 }
604 }
605
606 // process all the static initializers
607 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
608 if (l.head.getTag() != JCTree.METHODDEF &&
609 (TreeInfo.flags(l.head) & STATIC) != 0) {
610 scanDef(l.head);
611 errorUncaught();
612 }
613 }
614
615 // add intersection of all thrown clauses of initial constructors
616 // to set of caught exceptions, unless class is anonymous.
617 if (tree.name != names.empty) {
618 boolean firstConstructor = true;
619 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
620 if (TreeInfo.isInitialConstructor(l.head)) {
621 List<Type> mthrown =
622 ((JCMethodDecl) l.head).sym.type.getThrownTypes();
623 if (firstConstructor) {
624 caught = mthrown;
625 firstConstructor = false;
626 } else {
627 caught = chk.intersect(mthrown, caught);
628 }
629 }
630 }
631 }
632
633 // define all the instance fields
634 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
635 if (l.head.getTag() == JCTree.VARDEF) {
636 JCVariableDecl def = (JCVariableDecl)l.head;
637 if ((def.mods.flags & STATIC) == 0) {
638 VarSymbol sym = def.sym;
639 if (trackable(sym))
640 newVar(sym);
641 }
642 }
643 }
644
645 // process all the instance initializers
646 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
647 if (l.head.getTag() != JCTree.METHODDEF &&
648 (TreeInfo.flags(l.head) & STATIC) == 0) {
649 scanDef(l.head);
650 errorUncaught();
651 }
652 }
653
654 // in an anonymous class, add the set of thrown exceptions to
655 // the throws clause of the synthetic constructor and propagate
656 // outwards.
657 if (tree.name == names.empty) {
658 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
659 if (TreeInfo.isInitialConstructor(l.head)) {
660 JCMethodDecl mdef = (JCMethodDecl)l.head;
661 mdef.thrown = make.Types(thrown);
662 mdef.sym.type.setThrown(thrown);
663 }
664 }
665 thrownPrev = chk.union(thrown, thrownPrev);
666 }
667
668 // process all the methods
669 for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) {
670 if (l.head.getTag() == JCTree.METHODDEF) {
671 scan(l.head);
672 errorUncaught();
673 }
674 }
675
676 thrown = thrownPrev;
677 } finally {
678 pendingExits = pendingExitsPrev;
679 alive = alivePrev;
680 nextadr = nextadrPrev;
681 firstadr = firstadrPrev;
682 caught = caughtPrev;
683 classDef = classDefPrev;
684 lint = lintPrev;
685 }
686 }
687
688 public void visitMethodDef(JCMethodDecl tree) {
689 if (tree.body == null) return;
690
691 List<Type> caughtPrev = caught;
692 List<Type> mthrown = tree.sym.type.getThrownTypes();
693 Bits initsPrev = inits.dup();
694 Bits uninitsPrev = uninits.dup();
695 int nextadrPrev = nextadr;
696 int firstadrPrev = firstadr;
697 Lint lintPrev = lint;
698
699 lint = lint.augment(tree.sym.attributes_field);
700
701 assert pendingExits.isEmpty();
702
703 try {
704 boolean isInitialConstructor =
705 TreeInfo.isInitialConstructor(tree);
706
707 if (!isInitialConstructor)
708 firstadr = nextadr;
709 for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
710 JCVariableDecl def = l.head;
711 scan(def);
712 inits.incl(def.sym.adr);
713 uninits.excl(def.sym.adr);
714 }
715 if (isInitialConstructor)
716 caught = chk.union(caught, mthrown);
717 else if ((tree.sym.flags() & (BLOCK | STATIC)) != BLOCK)
718 caught = mthrown;
719 // else we are in an instance initializer block;
720 // leave caught unchanged.
721
722 alive = true;
723 scanStat(tree.body);
724
725 if (alive && tree.sym.type.getReturnType().tag != VOID)
726 log.error(TreeInfo.diagEndPos(tree.body), "missing.ret.stmt");
727
728 if (isInitialConstructor) {
729 for (int i = firstadr; i < nextadr; i++)
730 if (vars[i].owner == classDef.sym)
731 checkInit(TreeInfo.diagEndPos(tree.body), vars[i]);
732 }
733 List<PendingExit> exits = pendingExits.toList();
734 pendingExits = new ListBuffer<PendingExit>();
735 while (exits.nonEmpty()) {
736 PendingExit exit = exits.head;
737 exits = exits.tail;
738 if (exit.thrown == null) {
739 assert exit.tree.getTag() == JCTree.RETURN;
740 if (isInitialConstructor) {
741 inits = exit.inits;
742 for (int i = firstadr; i < nextadr; i++)
743 checkInit(exit.tree.pos(), vars[i]);
744 }
745 } else {
746 // uncaught throws will be reported later
747 pendingExits.append(exit);
748 }
749 }
750 } finally {
751 inits = initsPrev;
752 uninits = uninitsPrev;
753 nextadr = nextadrPrev;
754 firstadr = firstadrPrev;
755 caught = caughtPrev;
756 lint = lintPrev;
757 }
758 }
759
760 public void visitVarDef(JCVariableDecl tree) {
761 boolean track = trackable(tree.sym);
762 if (track && tree.sym.owner.kind == MTH) newVar(tree.sym);
763 if (tree.init != null) {
764 Lint lintPrev = lint;
765 lint = lint.augment(tree.sym.attributes_field);
766 try{
767 scanExpr(tree.init);
768 if (track) letInit(tree.pos(), tree.sym);
769 } finally {
770 lint = lintPrev;
771 }
772 }
773 }
774
775 public void visitBlock(JCBlock tree) {
776 int nextadrPrev = nextadr;
777 scanStats(tree.stats);
778 nextadr = nextadrPrev;
779 }
780
781 public void visitDoLoop(JCDoWhileLoop tree) {
782 ListBuffer<PendingExit> prevPendingExits = pendingExits;
783 boolean prevLoopPassTwo = loopPassTwo;
784 pendingExits = new ListBuffer<PendingExit>();
785 do {
786 Bits uninitsEntry = uninits.dup();
787 scanStat(tree.body);
788 alive |= resolveContinues(tree);
789 scanCond(tree.cond);
790 if (log.nerrors != 0 ||
791 loopPassTwo ||
792 uninitsEntry.diffSet(uninitsWhenTrue).nextBit(firstadr)==-1)
793 break;
794 inits = initsWhenTrue;
795 uninits = uninitsEntry.andSet(uninitsWhenTrue);
796 loopPassTwo = true;
797 alive = true;
798 } while (true);
799 loopPassTwo = prevLoopPassTwo;
800 inits = initsWhenFalse;
801 uninits = uninitsWhenFalse;
802 alive = alive && !tree.cond.type.isTrue();
803 alive |= resolveBreaks(tree, prevPendingExits);
804 }
805
806 public void visitWhileLoop(JCWhileLoop tree) {
807 ListBuffer<PendingExit> prevPendingExits = pendingExits;
808 boolean prevLoopPassTwo = loopPassTwo;
809 Bits initsCond;
810 Bits uninitsCond;
811 pendingExits = new ListBuffer<PendingExit>();
812 do {
813 Bits uninitsEntry = uninits.dup();
814 scanCond(tree.cond);
815 initsCond = initsWhenFalse;
816 uninitsCond = uninitsWhenFalse;
817 inits = initsWhenTrue;
818 uninits = uninitsWhenTrue;
819 alive = !tree.cond.type.isFalse();
820 scanStat(tree.body);
821 alive |= resolveContinues(tree);
822 if (log.nerrors != 0 ||
823 loopPassTwo ||
824 uninitsEntry.diffSet(uninits).nextBit(firstadr) == -1)
825 break;
826 uninits = uninitsEntry.andSet(uninits);
827 loopPassTwo = true;
828 alive = true;
829 } while (true);
830 loopPassTwo = prevLoopPassTwo;
831 inits = initsCond;
832 uninits = uninitsCond;
833 alive = resolveBreaks(tree, prevPendingExits) ||
834 !tree.cond.type.isTrue();
835 }
836
837 public void visitForLoop(JCForLoop tree) {
838 ListBuffer<PendingExit> prevPendingExits = pendingExits;
839 boolean prevLoopPassTwo = loopPassTwo;
840 int nextadrPrev = nextadr;
841 scanStats(tree.init);
842 Bits initsCond;
843 Bits uninitsCond;
844 pendingExits = new ListBuffer<PendingExit>();
845 do {
846 Bits uninitsEntry = uninits.dup();
847 if (tree.cond != null) {
848 scanCond(tree.cond);
849 initsCond = initsWhenFalse;
850 uninitsCond = uninitsWhenFalse;
851 inits = initsWhenTrue;
852 uninits = uninitsWhenTrue;
853 alive = !tree.cond.type.isFalse();
854 } else {
855 initsCond = inits.dup();
856 initsCond.inclRange(firstadr, nextadr);
857 uninitsCond = uninits.dup();
858 uninitsCond.inclRange(firstadr, nextadr);
859 alive = true;
860 }
861 scanStat(tree.body);
862 alive |= resolveContinues(tree);
863 scan(tree.step);
864 if (log.nerrors != 0 ||
865 loopPassTwo ||
866 uninitsEntry.dup().diffSet(uninits).nextBit(firstadr) == -1)
867 break;
868 uninits = uninitsEntry.andSet(uninits);
869 loopPassTwo = true;
870 alive = true;
871 } while (true);
872 loopPassTwo = prevLoopPassTwo;
873 inits = initsCond;
874 uninits = uninitsCond;
875 alive = resolveBreaks(tree, prevPendingExits) ||
876 tree.cond != null && !tree.cond.type.isTrue();
877 nextadr = nextadrPrev;
878 }
879
880 public void visitForeachLoop(JCEnhancedForLoop tree) {
881 visitVarDef(tree.var);
882
883 ListBuffer<PendingExit> prevPendingExits = pendingExits;
884 boolean prevLoopPassTwo = loopPassTwo;
885 int nextadrPrev = nextadr;
886 scan(tree.expr);
887 Bits initsStart = inits.dup();
888 Bits uninitsStart = uninits.dup();
889
890 letInit(tree.pos(), tree.var.sym);
891 pendingExits = new ListBuffer<PendingExit>();
892 do {
893 Bits uninitsEntry = uninits.dup();
894 scanStat(tree.body);
895 alive |= resolveContinues(tree);
896 if (log.nerrors != 0 ||
897 loopPassTwo ||
898 uninitsEntry.diffSet(uninits).nextBit(firstadr) == -1)
899 break;
900 uninits = uninitsEntry.andSet(uninits);
901 loopPassTwo = true;
902 alive = true;
903 } while (true);
904 loopPassTwo = prevLoopPassTwo;
905 inits = initsStart;
906 uninits = uninitsStart.andSet(uninits);
907 resolveBreaks(tree, prevPendingExits);
908 alive = true;
909 nextadr = nextadrPrev;
910 }
911
912 public void visitLabelled(JCLabeledStatement tree) {
913 ListBuffer<PendingExit> prevPendingExits = pendingExits;
914 pendingExits = new ListBuffer<PendingExit>();
915 scanStat(tree.body);
916 alive |= resolveBreaks(tree, prevPendingExits);
917 }
918
919 public void visitSwitch(JCSwitch tree) {
920 ListBuffer<PendingExit> prevPendingExits = pendingExits;
921 pendingExits = new ListBuffer<PendingExit>();
922 int nextadrPrev = nextadr;
923 scanExpr(tree.selector);
924 Bits initsSwitch = inits;
925 Bits uninitsSwitch = uninits.dup();
926 boolean hasDefault = false;
927 for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {
928 alive = true;
929 inits = initsSwitch.dup();
930 uninits = uninits.andSet(uninitsSwitch);
931 JCCase c = l.head;
932 if (c.pat == null)
933 hasDefault = true;
934 else
935 scanExpr(c.pat);
936 scanStats(c.stats);
937 addVars(c.stats, initsSwitch, uninitsSwitch);
938 // Warn about fall-through if lint switch fallthrough enabled.
939 if (!loopPassTwo &&
940 alive &&
941 lint.isEnabled(Lint.LintCategory.FALLTHROUGH) &&
942 c.stats.nonEmpty() && l.tail.nonEmpty())
943 log.warning(l.tail.head.pos(),
944 "possible.fall-through.into.case");
945 }
946 if (!hasDefault) {
947 inits.andSet(initsSwitch);
948 alive = true;
949 }
950 alive |= resolveBreaks(tree, prevPendingExits);
951 nextadr = nextadrPrev;
952 }
953 // where
954 /** Add any variables defined in stats to inits and uninits. */
955 private static void addVars(List<JCStatement> stats, Bits inits,
956 Bits uninits) {
957 for (;stats.nonEmpty(); stats = stats.tail) {
958 JCTree stat = stats.head;
959 if (stat.getTag() == JCTree.VARDEF) {
960 int adr = ((JCVariableDecl) stat).sym.adr;
961 inits.excl(adr);
962 uninits.incl(adr);
963 }
964 }
965 }
966
967 public void visitTry(JCTry tree) {
968 unrefdResources = List.nil();
969 for (JCTree resource : tree.resources) {
970 if (resource instanceof JCVariableDecl) {
971 visitVarDef((JCVariableDecl) resource);
972 } else if (resource instanceof JCExpression) {
973 scanExpr((JCExpression) resource);
974 } else {
975 throw new AssertionError(tree); // parser error
976 }
977 }
978 List<Type> caughtPrev = caught;
979 List<Type> thrownPrev = thrown;
980 thrown = List.nil();
981 for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
982 List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
983 ((JCTypeDisjoint)l.head.param.vartype).components :
984 List.of(l.head.param.vartype);
985 for (JCExpression ct : subClauses) {
986 caught = chk.incl(ct.type, caught);
987 }
988 }
989 Bits uninitsTryPrev = uninitsTry;
990 ListBuffer<PendingExit> prevPendingExits = pendingExits;
991 pendingExits = new ListBuffer<PendingExit>();
992 Bits initsTry = inits.dup();
993 uninitsTry = uninits.dup();
994 for (JCTree resource : tree.resources) {
995 MethodSymbol closeMethod =
996 (MethodSymbol)resource.type.tsym.members().lookup(names.close).sym;
997 for (Type thrownType : closeMethod.getThrownTypes()) {
998 markThrown(tree.body, thrownType);
999 }
1000 }
1001 scanStat(tree.body);
1002 List<Type> thrownInTry = thrown;
1003 thrown = thrownPrev;
1004 caught = caughtPrev;
1005 boolean aliveEnd = alive;
1006 uninitsTry.andSet(uninits);
1007 Bits initsEnd = inits;
1008 Bits uninitsEnd = uninits;
1009 int nextadrCatch = nextadr;
1010
1011 if (unrefdResources.nonEmpty()) {
1012 for (List<JCTree> l = tree.resources; l.nonEmpty(); l = l.tail) {
1013 if (l.head instanceof JCVariableDecl) {
1014 JCVariableDecl v = (JCVariableDecl) l.head;
1015 if (unrefdResources.contains(v.sym)) {
1016 log.warning(v.pos(),
1017 "automatic.resource.not.referenced", v.sym);
1018 }
1019 }
1020 }
1021 }
1022
1023 List<Type> caughtInTry = List.nil();
1024 for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
1025 alive = true;
1026 JCVariableDecl param = l.head.param;
1027 List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
1028 ((JCTypeDisjoint)l.head.param.vartype).components :
1029 List.of(l.head.param.vartype);
1030 List<Type> ctypes = List.nil();
1031 List<Type> rethrownTypes = chk.diff(thrownInTry, caughtInTry);
1032 for (JCExpression ct : subClauses) {
1033 Type exc = ct.type;
1034 ctypes = ctypes.append(exc);
1035 if (types.isSameType(exc, syms.objectType))
1036 continue;
1037 if (chk.subset(exc, caughtInTry)) {
1038 log.error(l.head.pos(),
1039 "except.already.caught", exc);
1040 } else if (!chk.isUnchecked(l.head.pos(), exc) &&
1041 exc.tsym != syms.throwableType.tsym &&
1042 exc.tsym != syms.exceptionType.tsym &&
1043 !chk.intersects(exc, thrownInTry)) {
1044 log.error(l.head.pos(),
1045 "except.never.thrown.in.try", exc);
1046 }
1047 caughtInTry = chk.incl(exc, caughtInTry);
1048 }
1049 inits = initsTry.dup();
1050 uninits = uninitsTry.dup();
1051 scan(param);
1052 inits.incl(param.sym.adr);
1053 uninits.excl(param.sym.adr);
1054 multicatchTypes.put(param.sym, chk.intersect(ctypes, rethrownTypes));
1055 scanStat(l.head.body);
1056 initsEnd.andSet(inits);
1057 uninitsEnd.andSet(uninits);
1058 nextadr = nextadrCatch;
1059 multicatchTypes.remove(param.sym);
1060 aliveEnd |= alive;
1061 }
1062 if (tree.finalizer != null) {
1063 List<Type> savedThrown = thrown;
1064 thrown = List.nil();
1065 inits = initsTry.dup();
1066 uninits = uninitsTry.dup();
1067 ListBuffer<PendingExit> exits = pendingExits;
1068 pendingExits = prevPendingExits;
1069 alive = true;
1070 scanStat(tree.finalizer);
1071 if (!alive) {
1072 // discard exits and exceptions from try and finally
1073 thrown = chk.union(thrown, thrownPrev);
1074 if (!loopPassTwo &&
1075 lint.isEnabled(Lint.LintCategory.FINALLY)) {
1076 log.warning(TreeInfo.diagEndPos(tree.finalizer),
1077 "finally.cannot.complete");
1078 }
1079 } else {
1080 thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry));
1081 thrown = chk.union(thrown, savedThrown);
1082 uninits.andSet(uninitsEnd);
1083 // FIX: this doesn't preserve source order of exits in catch
1084 // versus finally!
1085 while (exits.nonEmpty()) {
1086 PendingExit exit = exits.next();
1087 if (exit.inits != null) {
1088 exit.inits.orSet(inits);
1089 exit.uninits.andSet(uninits);
1090 }
1091 pendingExits.append(exit);
1092 }
1093 inits.orSet(initsEnd);
1094 alive = aliveEnd;
1095 }
1096 } else {
1097 thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry));
1098 inits = initsEnd;
1099 uninits = uninitsEnd;
1100 alive = aliveEnd;
1101 ListBuffer<PendingExit> exits = pendingExits;
1102 pendingExits = prevPendingExits;
1103 while (exits.nonEmpty()) pendingExits.append(exits.next());
1104 }
1105 uninitsTry.andSet(uninitsTryPrev).andSet(uninits);
1106 }
1107
1108 public void visitConditional(JCConditional tree) {
1109 scanCond(tree.cond);
1110 Bits initsBeforeElse = initsWhenFalse;
1111 Bits uninitsBeforeElse = uninitsWhenFalse;
1112 inits = initsWhenTrue;
1113 uninits = uninitsWhenTrue;
1114 if (tree.truepart.type.tag == BOOLEAN &&
1115 tree.falsepart.type.tag == BOOLEAN) {
1116 // if b and c are boolean valued, then
1117 // v is (un)assigned after a?b:c when true iff
1118 // v is (un)assigned after b when true and
1119 // v is (un)assigned after c when true
1120 scanCond(tree.truepart);
1121 Bits initsAfterThenWhenTrue = initsWhenTrue.dup();
1122 Bits initsAfterThenWhenFalse = initsWhenFalse.dup();
1123 Bits uninitsAfterThenWhenTrue = uninitsWhenTrue.dup();
1124 Bits uninitsAfterThenWhenFalse = uninitsWhenFalse.dup();
1125 inits = initsBeforeElse;
1126 uninits = uninitsBeforeElse;
1127 scanCond(tree.falsepart);
1128 initsWhenTrue.andSet(initsAfterThenWhenTrue);
1129 initsWhenFalse.andSet(initsAfterThenWhenFalse);
1130 uninitsWhenTrue.andSet(uninitsAfterThenWhenTrue);
1131 uninitsWhenFalse.andSet(uninitsAfterThenWhenFalse);
1132 } else {
1133 scanExpr(tree.truepart);
1134 Bits initsAfterThen = inits.dup();
1135 Bits uninitsAfterThen = uninits.dup();
1136 inits = initsBeforeElse;
1137 uninits = uninitsBeforeElse;
1138 scanExpr(tree.falsepart);
1139 inits.andSet(initsAfterThen);
1140 uninits.andSet(uninitsAfterThen);
1141 }
1142 }
1143
1144 public void visitIf(JCIf tree) {
1145 scanCond(tree.cond);
1146 Bits initsBeforeElse = initsWhenFalse;
1147 Bits uninitsBeforeElse = uninitsWhenFalse;
1148 inits = initsWhenTrue;
1149 uninits = uninitsWhenTrue;
1150 scanStat(tree.thenpart);
1151 if (tree.elsepart != null) {
1152 boolean aliveAfterThen = alive;
1153 alive = true;
1154 Bits initsAfterThen = inits.dup();
1155 Bits uninitsAfterThen = uninits.dup();
1156 inits = initsBeforeElse;
1157 uninits = uninitsBeforeElse;
1158 scanStat(tree.elsepart);
1159 inits.andSet(initsAfterThen);
1160 uninits.andSet(uninitsAfterThen);
1161 alive = alive | aliveAfterThen;
1162 } else {
1163 inits.andSet(initsBeforeElse);
1164 uninits.andSet(uninitsBeforeElse);
1165 alive = true;
1166 }
1167 }
1168
1169
1170
1171 public void visitBreak(JCBreak tree) {
1172 recordExit(tree);
1173 }
1174
1175 public void visitContinue(JCContinue tree) {
1176 recordExit(tree);
1177 }
1178
1179 public void visitReturn(JCReturn tree) {
1180 scanExpr(tree.expr);
1181 // if not initial constructor, should markDead instead of recordExit
1182 recordExit(tree);
1183 }
1184
1185 public void visitThrow(JCThrow tree) {
1186 scanExpr(tree.expr);
1187 Symbol sym = TreeInfo.symbol(tree.expr);
1188 if (sym != null &&
1189 sym.kind == VAR &&
1190 (sym.flags() & FINAL) != 0 &&
1191 multicatchTypes.get(sym) != null &&
1192 allowRethrowAnalysis) {
1193 for (Type t : multicatchTypes.get(sym)) {
1194 markThrown(tree, t);
1195 }
1196 }
1197 else {
1198 markThrown(tree, tree.expr.type);
1199 }
1200 markDead();
1201 }
1202
1203 public void visitApply(JCMethodInvocation tree) {
1204 scanExpr(tree.meth);
1205 scanExprs(tree.args);
1206 for (List<Type> l = tree.meth.type.getThrownTypes(); l.nonEmpty(); l = l.tail)
1207 markThrown(tree, l.head);
1208 }
1209
1210 public void visitNewClass(JCNewClass tree) {
1211 scanExpr(tree.encl);
1212 scanExprs(tree.args);
1213 // scan(tree.def);
1214 for (List<Type> l = tree.constructorType.getThrownTypes();
1215 l.nonEmpty();
1216 l = l.tail) {
1217 markThrown(tree, l.head);
1218 }
1219 List<Type> caughtPrev = caught;
1220 try {
1221 // If the new class expression defines an anonymous class,
1222 // analysis of the anonymous constructor may encounter thrown
1223 // types which are unsubstituted type variables.
1224 // However, since the constructor's actual thrown types have
1225 // already been marked as thrown, it is safe to simply include
1226 // each of the constructor's formal thrown types in the set of
1227 // 'caught/declared to be thrown' types, for the duration of
1228 // the class def analysis.
1229 if (tree.def != null)
1230 for (List<Type> l = tree.constructor.type.getThrownTypes();
1231 l.nonEmpty();
1232 l = l.tail) {
1233 caught = chk.incl(l.head, caught);
1234 }
1235 scan(tree.def);
1236 }
1237 finally {
1238 caught = caughtPrev;
1239 }
1240 }
1241
1242 public void visitNewArray(JCNewArray tree) {
1243 scanExprs(tree.dims);
1244 scanExprs(tree.elems);
1245 }
1246
1247 public void visitAssert(JCAssert tree) {
1248 Bits initsExit = inits.dup();
1249 Bits uninitsExit = uninits.dup();
1250 scanCond(tree.cond);
1251 uninitsExit.andSet(uninitsWhenTrue);
1252 if (tree.detail != null) {
1253 inits = initsWhenFalse;
1254 uninits = uninitsWhenFalse;
1255 scanExpr(tree.detail);
1256 }
1257 inits = initsExit;
1258 uninits = uninitsExit;
1259 }
1260
1261 public void visitAssign(JCAssign tree) {
1262 JCTree lhs = TreeInfo.skipParens(tree.lhs);
1263 if (!(lhs instanceof JCIdent)) scanExpr(lhs);
1264 scanExpr(tree.rhs);
1265 letInit(lhs);
1266 }
1267
1268 public void visitAssignop(JCAssignOp tree) {
1269 scanExpr(tree.lhs);
1270 scanExpr(tree.rhs);
1271 letInit(tree.lhs);
1272 }
1273
1274 public void visitUnary(JCUnary tree) {
1275 switch (tree.getTag()) {
1276 case JCTree.NOT:
1277 scanCond(tree.arg);
1278 Bits t = initsWhenFalse;
1279 initsWhenFalse = initsWhenTrue;
1280 initsWhenTrue = t;
1281 t = uninitsWhenFalse;
1282 uninitsWhenFalse = uninitsWhenTrue;
1283 uninitsWhenTrue = t;
1284 break;
1285 case JCTree.PREINC: case JCTree.POSTINC:
1286 case JCTree.PREDEC: case JCTree.POSTDEC:
1287 scanExpr(tree.arg);
1288 letInit(tree.arg);
1289 break;
1290 default:
1291 scanExpr(tree.arg);
1292 }
1293 }
1294
1295 public void visitBinary(JCBinary tree) {
1296 switch (tree.getTag()) {
1297 case JCTree.AND:
1298 scanCond(tree.lhs);
1299 Bits initsWhenFalseLeft = initsWhenFalse;
1300 Bits uninitsWhenFalseLeft = uninitsWhenFalse;
1301 inits = initsWhenTrue;
1302 uninits = uninitsWhenTrue;
1303 scanCond(tree.rhs);
1304 initsWhenFalse.andSet(initsWhenFalseLeft);
1305 uninitsWhenFalse.andSet(uninitsWhenFalseLeft);
1306 break;
1307 case JCTree.OR:
1308 scanCond(tree.lhs);
1309 Bits initsWhenTrueLeft = initsWhenTrue;
1310 Bits uninitsWhenTrueLeft = uninitsWhenTrue;
1311 inits = initsWhenFalse;
1312 uninits = uninitsWhenFalse;
1313 scanCond(tree.rhs);
1314 initsWhenTrue.andSet(initsWhenTrueLeft);
1315 uninitsWhenTrue.andSet(uninitsWhenTrueLeft);
1316 break;
1317 default:
1318 scanExpr(tree.lhs);
1319 scanExpr(tree.rhs);
1320 }
1321 }
1322
1323 public void visitAnnotatedType(JCAnnotatedType tree) {
1324 // annotations don't get scanned
1325 tree.underlyingType.accept(this);
1326 }
1327
1328 public void visitIdent(JCIdent tree) {
1329 if (tree.sym.kind == VAR) {
1330 checkInit(tree.pos(), (VarSymbol)tree.sym);
1331 referenced(tree.sym);
1332 }
1333 }
1334
1335 void referenced(Symbol sym) {
1336 if (unrefdResources != null && unrefdResources.contains(sym)) {
1337 ListBuffer<Symbol> lb = new ListBuffer<Symbol>();
1338 for (List<Symbol> l = unrefdResources; l.nonEmpty(); l = l.tail)
1339 if (l.head != sym)
1340 lb.add(l.head);
1341 unrefdResources = lb.toList();
1342 }
1343 }
1344
1345 public void visitTypeCast(JCTypeCast tree) {
1346 super.visitTypeCast(tree);
1347 if (!tree.type.isErroneous()
1348 && lint.isEnabled(Lint.LintCategory.CAST)
1349 && types.isSameType(tree.expr.type, tree.clazz.type)
1350 && !(ignoreAnnotatedCasts && containsTypeAnnotation(tree.clazz))) {
1351 log.warning(tree.pos(), "redundant.cast", tree.expr.type);
1352 }
1353 }
1354
1355 public void visitTopLevel(JCCompilationUnit tree) {
1356 // Do nothing for TopLevel since each class is visited individually
1357 }
1358
1359 /**************************************************************************
1360 * utility methods for ignoring type-annotated casts lint checking
1361 *************************************************************************/
1362 private static final boolean ignoreAnnotatedCasts = true;
1363 private static class AnnotationFinder extends TreeScanner {
1364 public boolean foundTypeAnno = false;
1365 public void visitAnnotation(JCAnnotation tree) {
1366 foundTypeAnno = foundTypeAnno || (tree instanceof JCTypeAnnotation);
1367 }
1368 }
1369
1370 private boolean containsTypeAnnotation(JCTree e) {
1371 AnnotationFinder finder = new AnnotationFinder();
1372 finder.scan(e);
1373 return finder.foundTypeAnno;
1374 }
1375
1376 /**************************************************************************
1377 * main method
1378 *************************************************************************/
1379
1380 /** Perform definite assignment/unassignment analysis on a tree.
1381 */
1382 public void analyzeTree(JCTree tree, TreeMaker make) {
1383 try {
1384 this.make = make;
1385 inits = new Bits();
1386 uninits = new Bits();
1387 uninitsTry = new Bits();
1388 initsWhenTrue = initsWhenFalse =
1389 uninitsWhenTrue = uninitsWhenFalse = null;
1390 if (vars == null)
1391 vars = new VarSymbol[32];
1392 else
1393 for (int i=0; i<vars.length; i++)
1394 vars[i] = null;
1395 firstadr = 0;
1396 nextadr = 0;
1397 pendingExits = new ListBuffer<PendingExit>();
1398 multicatchTypes = new HashMap<Symbol, List<Type>>();
1399 alive = true;
1400 this.thrown = this.caught = null;
1401 this.classDef = null;
1402 scan(tree);
1403 } finally {
1404 // note that recursive invocations of this method fail hard
1405 inits = uninits = uninitsTry = null;
1406 initsWhenTrue = initsWhenFalse =
1407 uninitsWhenTrue = uninitsWhenFalse = null;
1408 if (vars != null) for (int i=0; i<vars.length; i++)
1409 vars[i] = null;
1410 firstadr = 0;
1411 nextadr = 0;
1412 pendingExits = null;
1413 this.make = null;
1414 this.thrown = this.caught = null;
1415 this.classDef = null;
1416 }
1417 }
1418 }