Repository navigation
Expand file tree
/
Copy pathControlFlowGraph.qll
More file actions
692 lines (581 loc) · 21.1 KB
/
Copy pathControlFlowGraph.qll
File metadata and controls
692 lines (581 loc) · 21.1 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
/**
* Provides classes representing the control flow graph within callables.
*/
overlay[local?]
module;
import java
private import codeql.controlflow.ControlFlowGraph
private import codeql.controlflow.SuccessorType
private import controlflow.internal.Preconditions
private module Cfg0 = Make0<Location, Ast>;
private module Cfg1 = Make1<Input>;
private module Cfg2 = Make2<Input>;
private import Cfg0
private import Cfg1
private import Cfg2
import Public
/** Provides an implementation of the AST signature for Java. */
private module Ast implements AstSig<Location> {
private import java as J
class AstNode = ExprParent;
private predicate skipControlFlow(AstNode e) {
e.(Expr).getParent*() instanceof Annotation or
e instanceof TypeAccess or
e instanceof ArrayTypeAccess or
e instanceof UnionTypeAccess or
e instanceof IntersectionTypeAccess or
e instanceof WildcardTypeAccess or
// Switch cases of the form `case e1 -> e2;` skip the ExprStmt and treat
// the right-hand side as an expression. See `SwitchCase.getRuleExpression()`.
any(SwitchCase sc).getRuleExpression() = e.(J::ExprStmt).getExpr()
}
AstNode getChild(AstNode n, int index) {
not skipControlFlow(result) and
not skipControlFlow(n) and
result.(Expr).isNthChildOf(n, index)
or
result.(Stmt).isNthChildOf(n, index)
or
result = n.(SwitchCase).getRuleExpression() and index = -1
}
Callable getEnclosingCallable(AstNode node) {
result = node.(Expr).getEnclosingCallable() or
result = node.(Stmt).getEnclosingCallable()
}
class Callable = J::Callable;
AstNode callableGetBody(Callable c) { result = c.getBody() }
// TODO: Implement in order to include parameters in the CFG
class Parameter extends AstNode {
Parameter() { none() }
AstNode getPattern() { none() }
Expr getDefaultValue() { none() }
}
Parameter callableGetParameter(Callable c, int i) { result = c.getParameter(i) }
class Stmt = J::Stmt;
class LabeledStmt = J::LabeledStmt;
class Expr = J::Expr;
class BlockStmt = J::BlockStmt;
class ExprStmt extends J::ExprStmt {
ExprStmt() { not skipControlFlow(this) }
}
class IfStmt = J::IfStmt;
class LoopStmt = J::LoopStmt;
class WhileStmt = J::WhileStmt;
class DoStmt = J::DoStmt;
class UntilStmt extends LoopStmt {
UntilStmt() { none() }
}
final private class FinalForStmt = J::ForStmt;
class ForStmt extends FinalForStmt {
AstNode getInit(int index) { result = super.getInit(index) }
AstNode getUpdate(int index) { result = super.getUpdate(index) }
}
final private class FinalEnhancedForStmt = J::EnhancedForStmt;
class ForEachStmt extends FinalEnhancedForStmt {
Expr getVariable() { result = super.getVariable() }
Expr getCollection() { result = super.getExpr() }
}
class BreakStmt extends Stmt {
BreakStmt() { this instanceof J::BreakStmt or this instanceof YieldStmt }
}
class ContinueStmt = J::ContinueStmt;
class GotoStmt extends Stmt {
GotoStmt() { none() }
}
class ReturnStmt = J::ReturnStmt;
class Throw = J::ThrowStmt;
final private class FinalTryStmt = J::TryStmt;
class TryStmt extends FinalTryStmt {
AstNode getBody(int index) {
result = super.getResource(index)
or
index = count(super.getAResource()) and
result = super.getBlock()
}
CatchClause getCatch(int index) { result = super.getCatchClause(index) }
Stmt getFinally() { result = super.getFinally() }
}
final private class FinalCatchClause = J::CatchClause;
class CatchClause extends FinalCatchClause {
AstNode getPattern() { result = super.getVariable() }
AstNode getVariable() { none() }
Expr getCondition() { none() }
Stmt getBody() { result = super.getBlock() }
}
class Switch extends AstNode {
Switch() {
this instanceof SwitchStmt or
this instanceof SwitchExpr
}
Expr getExpr() {
result = this.(SwitchStmt).getExpr() or
result = this.(SwitchExpr).getExpr()
}
Case getCase(int index) {
result = this.(SwitchStmt).getCase(index) or
result = this.(SwitchExpr).getCase(index)
}
Stmt getStmt(int index) {
result = this.(SwitchStmt).getStmt(index) or
result = this.(SwitchExpr).getStmt(index)
}
}
class Case extends AstNode instanceof J::SwitchCase {
/** Gets the pattern being matched by this case at the specified (zero-based) `index`. */
AstNode getPattern(int index) {
result = this.(PatternCase).getPattern(index) or
result = this.(ConstCase).getValue(index)
}
/** Gets the guard expression of this case, if any. */
Expr getGuard() { result = this.(PatternCase).getGuard() }
/**
* Gets the body of this case, if any.
*
* A case can either have a body as a single child AST node given by this
* predicate, or it can have an implicit body given by the sequence of
* statements between this case and the next case.
*/
AstNode getBody() {
result = this.(J::SwitchCase).getRuleExpression()
or
result = this.(J::SwitchCase).getRuleStatement()
}
}
class DefaultCase extends Case instanceof J::DefaultCase { }
class ConditionalExpr = J::ConditionalExpr;
class BinaryExpr = J::BinaryExpr;
class LogicalAndExpr = AndLogicalExpr;
class LogicalOrExpr = OrLogicalExpr;
class NullCoalescingExpr extends BinaryExpr {
NullCoalescingExpr() { none() }
}
class UnaryExpr = J::UnaryExpr;
class LogicalNotExpr = LogNotExpr;
class Assignment = J::Assignment;
class AssignExpr = J::AssignExpr;
class CompoundAssignment = J::AssignOp;
class AssignLogicalAndExpr extends CompoundAssignment {
AssignLogicalAndExpr() { none() }
}
class AssignLogicalOrExpr extends CompoundAssignment {
AssignLogicalOrExpr() { none() }
}
class AssignNullCoalescingExpr extends CompoundAssignment {
AssignNullCoalescingExpr() { none() }
}
final private class FinalBooleanLiteral = J::BooleanLiteral;
class BooleanLiteral extends FinalBooleanLiteral {
boolean getValue() { result = this.getBooleanValue() }
}
final private class FinalInstanceOfExpr = J::InstanceOfExpr;
class PatternMatchExpr extends FinalInstanceOfExpr {
PatternMatchExpr() { this.isPattern() }
AstNode getPattern() { result = super.getPattern() }
}
}
private module Exceptions {
private predicate methodMayThrow(Method m) {
exists(Stmt stmt |
stmt instanceof ThrowStmt and
not stmt.(ThrowStmt).getParent() = any(Method m0).getBody()
or
uncheckedExceptionFromMethod(any(MethodCall call | call.getEnclosingStmt() = stmt))
|
stmt.getEnclosingCallable() = m and
not exists(TryStmt try |
exists(try.getACatchClause()) and try.getBlock() = stmt.getEnclosingStmt*()
)
)
}
/**
* Holds if an unchecked exception may occur in a precondition check or guard wrapper.
*/
private predicate uncheckedExceptionFromMethod(MethodCall call) {
(methodCallChecksArgument(call) or methodCallUnconditionallyThrows(call))
or
methodMayThrow(call.getMethod().getSourceDeclaration())
}
/**
* Holds if an unchecked exception from `c` may transfer control to a finally
* block inside which `c` is nested.
*/
private predicate uncheckedExceptionFromFinally(Call c) {
exists(TryStmt try |
c.getEnclosingStmt().getEnclosingStmt+() = try.getBlock() or
c.(Expr).getParent*() = try.getAResource()
|
exists(try.getFinally())
)
}
/**
* A throwable that's a (reflexive, transitive) supertype of an unchecked
* exception. Besides the unchecked exceptions themselves, this includes
* `java.lang.Throwable` and `java.lang.Exception`.
*/
private class UncheckedThrowableSuperType extends RefType {
UncheckedThrowableSuperType() {
this instanceof TypeThrowable or
this instanceof TypeException or
this instanceof UncheckedThrowableType
}
}
/**
* Holds if an unchecked exception from `n` may be caught by an enclosing
* catch clause.
*/
private predicate uncheckedExceptionFromCatch(Ast::AstNode n) {
exists(TryStmt try, UncheckedThrowableSuperType caught |
n.(Stmt).getEnclosingStmt+() = try.getBlock() or
n.(Expr).getEnclosingStmt().getEnclosingStmt+() = try.getBlock() or
n.(Expr).getParent*() = try.getAResource()
|
try.getACatchClause().getACaughtType() = caught and
(
caught instanceof TypeClassCastException and n instanceof CastExpr
or
caught instanceof TypeNullPointerException and n instanceof NotNullExpr
or
n instanceof Call
)
)
}
/**
* Holds if a catch clause of `try` catches checked exceptions of type
* `caught`, and that `call` is contained within the try block.
*/
private predicate checkedExceptionFromCatchCandidate(TryStmt try, RefType caught, Call call) {
(
call.getEnclosingStmt().getEnclosingStmt+() = try.getBlock() or
call.(Expr).getParent*() = try.getAResource()
) and
try.getACatchClause().getACaughtType() = caught and
not caught instanceof UncheckedThrowableSuperType
}
/**
* Holds if a catch clause of `try` catches checked exceptions of type
* `caught`, and that there is a call within the try block that declares that
* it may throw `caught` or a subtype thereof.
*/
private predicate declaredCheckedExceptionFromCatchCandidate(TryStmt try, RefType caught) {
exists(Call call |
checkedExceptionFromCatchCandidate(try, caught, call) and
call.getCallee().getAThrownExceptionType().getASourceSupertype*() = caught
)
}
/**
* Holds if `call` is contained within a try block that has a catch clause
* that catches a checked exception, but there is no call within the try
* block that declares that it may throw that exception, and no throw
* statement either. In this case, it is likely that the throws declaration
* for some reason was not extracted, so we conseratively assume that `call`
* may throw such an exception.
*/
private predicate checkedExceptionFromCatchCandidate(Call call) {
exists(TryStmt try, RefType caught |
checkedExceptionFromCatchCandidate(try, caught, call) and
not declaredCheckedExceptionFromCatchCandidate(try, caught) and
not exists(ThrowStmt throwstmt |
throwstmt.getEnclosingStmt+() = try.getBlock() and
throwstmt.getThrownExceptionType().getASourceSupertype*() = caught
)
)
}
/**
* Holds if `n` is expected to possibly throw an exception. This can either
* be due to a declared (likely checked) exception on a call target
* or due to an enclosing try/catch/finally.
*/
predicate mayThrow(Ast::AstNode n) {
exists(n.(Call).getCallee().getAThrownExceptionType())
or
checkedExceptionFromCatchCandidate(n)
or
uncheckedExceptionFromMethod(n)
or
uncheckedExceptionFromFinally(n)
or
uncheckedExceptionFromCatch(n)
}
}
private module NonReturningCalls {
/**
* A virtual method with a unique implementation. That is, the method does not
* participate in overriding and there are no call targets that could dispatch
* to both this and another method.
*/
private class EffectivelyNonVirtualMethod extends SrcMethod {
EffectivelyNonVirtualMethod() {
exists(this.getBody()) and
this.isVirtual() and
not this = any(Method m).getASourceOverriddenMethod() and
not this.overrides(_) and
// guard against implicit overrides of default methods
not this.getAPossibleImplementationOfSrcMethod() != this and
// guard against interface implementations in inheriting subclasses
not exists(SrcMethod m |
1 < strictcount(m.getAPossibleImplementationOfSrcMethod()) and
this = m.getAPossibleImplementationOfSrcMethod()
) and
// UnsupportedOperationException could indicate that this is meant to be overridden
not exists(ClassInstanceExpr ex |
this.getBody().getLastStmt().(ThrowStmt).getExpr() = ex and
ex.getConstructedType().hasQualifiedName("java.lang", "UnsupportedOperationException")
) and
// an unused parameter could indicate that this is meant to be overridden
forall(Parameter p | p = this.getAParameter() | exists(p.getAnAccess()))
}
/** Gets a `MethodCall` that calls this method. */
MethodCall getAnAccess() {
result.getMethod().getAPossibleImplementation() = pragma[only_bind_out](this)
}
}
/** Holds if a call to `m` indicates that `m` is expected to return. */
private predicate expectedReturn(EffectivelyNonVirtualMethod m) {
exists(Stmt s, BlockStmt b |
m.getAnAccess().getEnclosingStmt() = s and
b.getAStmt() = s and
not b.getLastStmt() = s
)
}
/**
* Gets a non-overridable method that always throws an exception or calls `exit`.
*/
private Method nonReturningMethod() {
result instanceof MethodExit
or
not result.isOverridable() and
exists(BlockStmt body |
body = result.getBody() and
not exists(ReturnStmt ret | ret.getEnclosingCallable() = result)
|
not result.getReturnType() instanceof VoidType or
body.getLastStmt() = nonReturningStmt()
)
}
/**
* Gets a virtual method that always throws an exception or calls `exit`.
*/
private EffectivelyNonVirtualMethod likelyNonReturningMethod() {
result.getReturnType() instanceof VoidType and
not exists(ReturnStmt ret | ret.getEnclosingCallable() = result) and
not expectedReturn(result) and
forall(Parameter p | p = result.getAParameter() | exists(p.getAnAccess())) and
result.getBody().getLastStmt() = nonReturningStmt()
}
/**
* Gets a `MethodCall` that always throws an exception or calls `exit`.
*/
MethodCall nonReturningMethodCall() {
methodCallUnconditionallyThrows(result) or
result.getMethod().getSourceDeclaration() = nonReturningMethod() or
result = likelyNonReturningMethod().getAnAccess()
}
/**
* Gets a statement that always throws an exception or calls `exit`.
*/
private Stmt nonReturningStmt() {
result instanceof ThrowStmt
or
result.(ExprStmt).getExpr() = nonReturningExpr()
or
result.(BlockStmt).getLastStmt() = nonReturningStmt()
or
exists(IfStmt ifstmt | ifstmt = result |
ifstmt.getThen() = nonReturningStmt() and
ifstmt.getElse() = nonReturningStmt()
)
or
exists(TryStmt try | try = result |
try.getBlock() = nonReturningStmt() and
forall(CatchClause cc | cc = try.getACatchClause() | cc.getBlock() = nonReturningStmt())
)
}
/**
* Gets an expression that always throws an exception or calls `exit`.
*/
private Expr nonReturningExpr() {
result = nonReturningMethodCall()
or
result.(StmtExpr).getStmt() = nonReturningStmt()
or
exists(WhenExpr whenexpr | whenexpr = result |
whenexpr.getBranch(_).isElseBranch() and
forex(WhenBranch whenbranch | whenbranch = whenexpr.getBranch(_) |
whenbranch.getRhs() = nonReturningStmt()
)
)
}
}
private module Input implements InputSig1, InputSig2 {
private import java as J
private import codeql.util.Void
predicate cfgCachedStageRef() { CfgCachedStage::ref() }
/** Holds if this catch clause catches all exceptions. */
predicate catchAll(Ast::CatchClause catch) {
catch.getACaughtType() instanceof TypeThrowable
or
exists(TryStmt try, int last |
catch.getACaughtType() instanceof TypeException and
try.getCatchClause(last) = catch and
not exists(try.getCatchClause(last + 1))
)
}
/** Holds if this switch must be exhaustive. */
predicate isExhaustive(Ast::Switch switch) {
// Switch expressions and enhanced switch blocks (those that use pattern
// cases or match null) must be exhaustive.
// See https://docs.oracle.com/javase/specs/jls/se21/html/jls-14.html#jls-14.11.2
switch instanceof SwitchExpr or
exists(switch.(SwitchStmt).getAPatternCase()) or
switch.(SwitchStmt).hasNullCase()
}
/** Holds if this case matches all possible values. */
predicate matchAll(Ast::Case c) {
c.(J::PatternCase).getAPattern().getType() instanceof TypeObject
}
private newtype TLabel =
TJavaLabel(string l) { exists(LabeledStmt lbl | l = lbl.getLabel()) } or
TYield()
class Label extends TLabel {
string toString() {
exists(string l | this = TJavaLabel(l) and result = l)
or
this = TYield() and result = "yield"
}
}
predicate hasLabel(Ast::AstNode n, Label l) {
l = TJavaLabel(n.(LabeledStmt).getLabel())
or
l = TJavaLabel(n.(BreakStmt).getLabel())
or
l = TJavaLabel(n.(ContinueStmt).getLabel())
or
l = TYield() and n instanceof YieldStmt
or
l = TYield() and n instanceof SwitchExpr
}
class CallableContext = Void;
predicate inConditionalContext(Ast::AstNode n, ConditionKind kind) {
kind.isBoolean() and
(
any(AssertStmt assertstmt).getExpr() = n or
any(WhenBranch whenbranch).getCondition() = n
)
}
predicate preOrderExpr(Expr e) { e instanceof WhenExpr }
predicate postOrInOrder(Ast::AstNode n) {
// expressions are already post-order, but we need the calls that are statements to be post-order as well
n instanceof Call
or
n instanceof SynchronizedStmt
}
private string assertThrowNodeTag() { result = "[assert-throw]" }
predicate additionalNode(Ast::AstNode n, string tag, NormalSuccessor t) {
n instanceof AssertStmt and tag = assertThrowNodeTag() and t instanceof DirectSuccessor
}
/**
* Holds if `ast` may result in an abrupt completion `c` originating at
* `n`. The boolean `always` indicates whether the abrupt completion
* always occurs or whether `n` may also terminate normally.
*/
predicate beginAbruptCompletion(
Ast::AstNode ast, PreControlFlowNode n, AbruptCompletion c, boolean always
) {
ast instanceof AssertStmt and
n.isAdditional(ast, assertThrowNodeTag()) and
c.asSimpleAbruptCompletion() instanceof ExceptionSuccessor and
always = true
or
Exceptions::mayThrow(ast) and
n.isIn(ast) and
c.asSimpleAbruptCompletion() instanceof ExceptionSuccessor and
always = false
or
ast = NonReturningCalls::nonReturningMethodCall() and
n.isIn(ast) and
c.asSimpleAbruptCompletion() instanceof ExceptionSuccessor and
always = true
}
/**
* Holds if an abrupt completion `c` from within `ast` is caught with
* flow continuing at `n`.
*/
predicate endAbruptCompletion(Ast::AstNode ast, PreControlFlowNode n, AbruptCompletion c) {
none()
}
/** Holds if there is a local non-abrupt step from `n1` to `n2`. */
predicate step(PreControlFlowNode n1, PreControlFlowNode n2) {
exists(AssertStmt assertstmt |
n1.isBefore(assertstmt) and
n2.isBefore(assertstmt.getExpr())
or
n1.isAfterValue(assertstmt.getExpr(), any(BooleanSuccessor s | s.getValue() = true)) and
n2.isAfter(assertstmt)
or
n1.isAfterValue(assertstmt.getExpr(), any(BooleanSuccessor s | s.getValue() = false)) and
(
n2.isBefore(assertstmt.getMessage())
or
not exists(assertstmt.getMessage()) and
n2.isAdditional(assertstmt, assertThrowNodeTag())
)
or
n1.isAfter(assertstmt.getMessage()) and
n2.isAdditional(assertstmt, assertThrowNodeTag())
)
or
// Synchronized statements execute their expression _before_ synchronization, so the CFG reflects that.
exists(SynchronizedStmt synch |
n1.isBefore(synch) and
n2.isBefore(synch.getExpr())
or
n1.isAfter(synch.getExpr()) and
n2.isIn(synch)
or
n1.isIn(synch) and
n2.isBefore(synch.getBlock())
or
n1.isAfter(synch.getBlock()) and
n2.isAfter(synch)
)
or
exists(WhenExpr whenexpr |
n1.isBefore(whenexpr) and
n2.isBefore(whenexpr.getBranch(0))
or
exists(int i, WhenBranch branch | branch = whenexpr.getBranch(i) |
// The `.isAfter(branch)` nodes are not needed, so they're simply skipped.
n1.isBefore(branch) and
n2.isBefore(branch.getCondition())
or
n1.isAfterTrue(branch.getCondition()) and
n2.isBefore(branch.getRhs())
or
n1.isAfterFalse(branch.getCondition()) and
(
n2.isBefore(whenexpr.getBranch(i + 1))
or
not exists(whenexpr.getBranch(i + 1)) and
n2.isAfter(whenexpr)
)
or
n1.isAfter(branch.getRhs()) and
n2.isAfter(whenexpr)
)
)
}
}
/** A control-flow node that branches based on a boolean condition. */
class ConditionNode extends ControlFlowNode {
ConditionNode() { exists(this.getASuccessor(any(BooleanSuccessor t))) }
/** Gets a true- or false-successor of the `ConditionNode`. */
ControlFlowNode getABranchSuccessor(boolean branch) {
result = this.getASuccessor(any(BooleanSuccessor t | t.getValue() = branch))
}
/** Gets a true-successor of the `ConditionNode`. */
ControlFlowNode getATrueSuccessor() { result = this.getABranchSuccessor(true) }
/** Gets a false-successor of the `ConditionNode`. */
ControlFlowNode getAFalseSuccessor() { result = this.getABranchSuccessor(false) }
/** Gets the condition of this `ConditionNode`. */
ExprParent getCondition() { result = this.asExpr() or result = this.asStmt() }
}