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NullabilityChecker.cpp
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1 //===-- NullabilityChecker.cpp - Nullability checker ----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This checker tries to find nullability violations. There are several kinds of
10 // possible violations:
11 // * Null pointer is passed to a pointer which has a _Nonnull type.
12 // * Null pointer is returned from a function which has a _Nonnull return type.
13 // * Nullable pointer is passed to a pointer which has a _Nonnull type.
14 // * Nullable pointer is returned from a function which has a _Nonnull return
15 // type.
16 // * Nullable pointer is dereferenced.
17 //
18 // This checker propagates the nullability information of the pointers and looks
19 // for the patterns that are described above. Explicit casts are trusted and are
20 // considered a way to suppress false positives for this checker. The other way
21 // to suppress warnings would be to add asserts or guarding if statements to the
22 // code. In addition to the nullability propagation this checker also uses some
23 // heuristics to suppress potential false positives.
24 //
25 //===----------------------------------------------------------------------===//
26 
28 
35 
36 #include "llvm/ADT/StringExtras.h"
37 #include "llvm/Support/Path.h"
38 
39 using namespace clang;
40 using namespace ento;
41 
42 namespace {
43 
44 /// Returns the most nullable nullability. This is used for message expressions
45 /// like [receiver method], where the nullability of this expression is either
46 /// the nullability of the receiver or the nullability of the return type of the
47 /// method, depending on which is more nullable. Contradicted is considered to
48 /// be the most nullable, to avoid false positive results.
49 Nullability getMostNullable(Nullability Lhs, Nullability Rhs) {
50  return static_cast<Nullability>(
51  std::min(static_cast<char>(Lhs), static_cast<char>(Rhs)));
52 }
53 
54 const char *getNullabilityString(Nullability Nullab) {
55  switch (Nullab) {
57  return "contradicted";
59  return "nullable";
61  return "unspecified";
63  return "nonnull";
64  }
65  llvm_unreachable("Unexpected enumeration.");
66  return "";
67 }
68 
69 // These enums are used as an index to ErrorMessages array.
70 enum class ErrorKind : int {
71  NilAssignedToNonnull,
72  NilPassedToNonnull,
73  NilReturnedToNonnull,
74  NullableAssignedToNonnull,
75  NullableReturnedToNonnull,
76  NullableDereferenced,
77  NullablePassedToNonnull
78 };
79 
80 class NullabilityChecker
81  : public Checker<check::Bind, check::PreCall, check::PreStmt<ReturnStmt>,
82  check::PostCall, check::PostStmt<ExplicitCastExpr>,
83  check::PostObjCMessage, check::DeadSymbols,
84  check::Event<ImplicitNullDerefEvent>> {
85  mutable std::unique_ptr<BugType> BT;
86 
87 public:
88  // If true, the checker will not diagnose nullabilility issues for calls
89  // to system headers. This option is motivated by the observation that large
90  // projects may have many nullability warnings. These projects may
91  // find warnings about nullability annotations that they have explicitly
92  // added themselves higher priority to fix than warnings on calls to system
93  // libraries.
94  DefaultBool NoDiagnoseCallsToSystemHeaders;
95 
96  void checkBind(SVal L, SVal V, const Stmt *S, CheckerContext &C) const;
97  void checkPostStmt(const ExplicitCastExpr *CE, CheckerContext &C) const;
98  void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
99  void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
100  void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
101  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
102  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
103  void checkEvent(ImplicitNullDerefEvent Event) const;
104 
105  void printState(raw_ostream &Out, ProgramStateRef State, const char *NL,
106  const char *Sep) const override;
107 
108  struct NullabilityChecksFilter {
109  DefaultBool CheckNullPassedToNonnull;
110  DefaultBool CheckNullReturnedFromNonnull;
111  DefaultBool CheckNullableDereferenced;
112  DefaultBool CheckNullablePassedToNonnull;
113  DefaultBool CheckNullableReturnedFromNonnull;
114 
115  CheckName CheckNameNullPassedToNonnull;
116  CheckName CheckNameNullReturnedFromNonnull;
117  CheckName CheckNameNullableDereferenced;
118  CheckName CheckNameNullablePassedToNonnull;
119  CheckName CheckNameNullableReturnedFromNonnull;
120  };
121 
122  NullabilityChecksFilter Filter;
123  // When set to false no nullability information will be tracked in
124  // NullabilityMap. It is possible to catch errors like passing a null pointer
125  // to a callee that expects nonnull argument without the information that is
126  // stroed in the NullabilityMap. This is an optimization.
127  DefaultBool NeedTracking;
128 
129 private:
130  class NullabilityBugVisitor : public BugReporterVisitor {
131  public:
132  NullabilityBugVisitor(const MemRegion *M) : Region(M) {}
133 
134  void Profile(llvm::FoldingSetNodeID &ID) const override {
135  static int X = 0;
136  ID.AddPointer(&X);
137  ID.AddPointer(Region);
138  }
139 
140  std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *N,
141  BugReporterContext &BRC,
142  BugReport &BR) override;
143 
144  private:
145  // The tracked region.
146  const MemRegion *Region;
147  };
148 
149  /// When any of the nonnull arguments of the analyzed function is null, do not
150  /// report anything and turn off the check.
151  ///
152  /// When \p SuppressPath is set to true, no more bugs will be reported on this
153  /// path by this checker.
154  void reportBugIfInvariantHolds(StringRef Msg, ErrorKind Error,
155  ExplodedNode *N, const MemRegion *Region,
156  CheckerContext &C,
157  const Stmt *ValueExpr = nullptr,
158  bool SuppressPath = false) const;
159 
160  void reportBug(StringRef Msg, ErrorKind Error, ExplodedNode *N,
161  const MemRegion *Region, BugReporter &BR,
162  const Stmt *ValueExpr = nullptr) const {
163  if (!BT)
164  BT.reset(new BugType(this, "Nullability", categories::MemoryError));
165 
166  auto R = llvm::make_unique<BugReport>(*BT, Msg, N);
167  if (Region) {
168  R->markInteresting(Region);
169  R->addVisitor(llvm::make_unique<NullabilityBugVisitor>(Region));
170  }
171  if (ValueExpr) {
172  R->addRange(ValueExpr->getSourceRange());
173  if (Error == ErrorKind::NilAssignedToNonnull ||
174  Error == ErrorKind::NilPassedToNonnull ||
175  Error == ErrorKind::NilReturnedToNonnull)
176  if (const auto *Ex = dyn_cast<Expr>(ValueExpr))
177  bugreporter::trackExpressionValue(N, Ex, *R);
178  }
179  BR.emitReport(std::move(R));
180  }
181 
182  /// If an SVal wraps a region that should be tracked, it will return a pointer
183  /// to the wrapped region. Otherwise it will return a nullptr.
184  const SymbolicRegion *getTrackRegion(SVal Val,
185  bool CheckSuperRegion = false) const;
186 
187  /// Returns true if the call is diagnosable in the current analyzer
188  /// configuration.
189  bool isDiagnosableCall(const CallEvent &Call) const {
190  if (NoDiagnoseCallsToSystemHeaders && Call.isInSystemHeader())
191  return false;
192 
193  return true;
194  }
195 };
196 
197 class NullabilityState {
198 public:
199  NullabilityState(Nullability Nullab, const Stmt *Source = nullptr)
200  : Nullab(Nullab), Source(Source) {}
201 
202  const Stmt *getNullabilitySource() const { return Source; }
203 
204  Nullability getValue() const { return Nullab; }
205 
206  void Profile(llvm::FoldingSetNodeID &ID) const {
207  ID.AddInteger(static_cast<char>(Nullab));
208  ID.AddPointer(Source);
209  }
210 
211  void print(raw_ostream &Out) const {
212  Out << getNullabilityString(Nullab) << "\n";
213  }
214 
215 private:
216  Nullability Nullab;
217  // Source is the expression which determined the nullability. For example in a
218  // message like [nullable nonnull_returning] has nullable nullability, because
219  // the receiver is nullable. Here the receiver will be the source of the
220  // nullability. This is useful information when the diagnostics are generated.
221  const Stmt *Source;
222 };
223 
224 bool operator==(NullabilityState Lhs, NullabilityState Rhs) {
225  return Lhs.getValue() == Rhs.getValue() &&
226  Lhs.getNullabilitySource() == Rhs.getNullabilitySource();
227 }
228 
229 } // end anonymous namespace
230 
231 REGISTER_MAP_WITH_PROGRAMSTATE(NullabilityMap, const MemRegion *,
232  NullabilityState)
233 
234 // We say "the nullability type invariant is violated" when a location with a
235 // non-null type contains NULL or a function with a non-null return type returns
236 // NULL. Violations of the nullability type invariant can be detected either
237 // directly (for example, when NULL is passed as an argument to a nonnull
238 // parameter) or indirectly (for example, when, inside a function, the
239 // programmer defensively checks whether a nonnull parameter contains NULL and
240 // finds that it does).
241 //
242 // As a matter of policy, the nullability checker typically warns on direct
243 // violations of the nullability invariant (although it uses various
244 // heuristics to suppress warnings in some cases) but will not warn if the
245 // invariant has already been violated along the path (either directly or
246 // indirectly). As a practical matter, this prevents the analyzer from
247 // (1) warning on defensive code paths where a nullability precondition is
248 // determined to have been violated, (2) warning additional times after an
249 // initial direct violation has been discovered, and (3) warning after a direct
250 // violation that has been implicitly or explicitly suppressed (for
251 // example, with a cast of NULL to _Nonnull). In essence, once an invariant
252 // violation is detected on a path, this checker will be essentially turned off
253 // for the rest of the analysis
254 //
255 // The analyzer takes this approach (rather than generating a sink node) to
256 // ensure coverage of defensive paths, which may be important for backwards
257 // compatibility in codebases that were developed without nullability in mind.
258 REGISTER_TRAIT_WITH_PROGRAMSTATE(InvariantViolated, bool)
259 
260 enum class NullConstraint { IsNull, IsNotNull, Unknown };
261 
262 static NullConstraint getNullConstraint(DefinedOrUnknownSVal Val,
264  ConditionTruthVal Nullness = State->isNull(Val);
265  if (Nullness.isConstrainedFalse())
266  return NullConstraint::IsNotNull;
267  if (Nullness.isConstrainedTrue())
268  return NullConstraint::IsNull;
270 }
271 
272 const SymbolicRegion *
273 NullabilityChecker::getTrackRegion(SVal Val, bool CheckSuperRegion) const {
274  if (!NeedTracking)
275  return nullptr;
276 
277  auto RegionSVal = Val.getAs<loc::MemRegionVal>();
278  if (!RegionSVal)
279  return nullptr;
280 
281  const MemRegion *Region = RegionSVal->getRegion();
282 
283  if (CheckSuperRegion) {
284  if (auto FieldReg = Region->getAs<FieldRegion>())
285  return dyn_cast<SymbolicRegion>(FieldReg->getSuperRegion());
286  if (auto ElementReg = Region->getAs<ElementRegion>())
287  return dyn_cast<SymbolicRegion>(ElementReg->getSuperRegion());
288  }
289 
290  return dyn_cast<SymbolicRegion>(Region);
291 }
292 
293 std::shared_ptr<PathDiagnosticPiece>
294 NullabilityChecker::NullabilityBugVisitor::VisitNode(const ExplodedNode *N,
295  BugReporterContext &BRC,
296  BugReport &BR) {
297  ProgramStateRef State = N->getState();
298  ProgramStateRef StatePrev = N->getFirstPred()->getState();
299 
300  const NullabilityState *TrackedNullab = State->get<NullabilityMap>(Region);
301  const NullabilityState *TrackedNullabPrev =
302  StatePrev->get<NullabilityMap>(Region);
303  if (!TrackedNullab)
304  return nullptr;
305 
306  if (TrackedNullabPrev &&
307  TrackedNullabPrev->getValue() == TrackedNullab->getValue())
308  return nullptr;
309 
310  // Retrieve the associated statement.
311  const Stmt *S = TrackedNullab->getNullabilitySource();
312  if (!S || S->getBeginLoc().isInvalid()) {
314  }
315 
316  if (!S)
317  return nullptr;
318 
319  std::string InfoText =
320  (llvm::Twine("Nullability '") +
321  getNullabilityString(TrackedNullab->getValue()) + "' is inferred")
322  .str();
323 
324  // Generate the extra diagnostic.
325  PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
326  N->getLocationContext());
327  return std::make_shared<PathDiagnosticEventPiece>(Pos, InfoText, true,
328  nullptr);
329 }
330 
331 /// Returns true when the value stored at the given location has been
332 /// constrained to null after being passed through an object of nonnnull type.
334  SVal LV, QualType T) {
336  return false;
337 
338  auto RegionVal = LV.getAs<loc::MemRegionVal>();
339  if (!RegionVal)
340  return false;
341 
342  // If the value was constrained to null *after* it was passed through that
343  // location, it could not have been a concrete pointer *when* it was passed.
344  // In that case we would have handled the situation when the value was
345  // bound to that location, by emitting (or not emitting) a report.
346  // Therefore we are only interested in symbolic regions that can be either
347  // null or non-null depending on the value of their respective symbol.
348  auto StoredVal = State->getSVal(*RegionVal).getAs<loc::MemRegionVal>();
349  if (!StoredVal || !isa<SymbolicRegion>(StoredVal->getRegion()))
350  return false;
351 
352  if (getNullConstraint(*StoredVal, State) == NullConstraint::IsNull)
353  return true;
354 
355  return false;
356 }
357 
358 static bool
361  const LocationContext *LocCtxt) {
362  for (const auto *ParamDecl : Params) {
363  if (ParamDecl->isParameterPack())
364  break;
365 
366  SVal LV = State->getLValue(ParamDecl, LocCtxt);
368  ParamDecl->getType())) {
369  return true;
370  }
371  }
372  return false;
373 }
374 
375 static bool
377  const LocationContext *LocCtxt) {
378  auto *MD = dyn_cast<ObjCMethodDecl>(LocCtxt->getDecl());
379  if (!MD || !MD->isInstanceMethod())
380  return false;
381 
382  const ImplicitParamDecl *SelfDecl = LocCtxt->getSelfDecl();
383  if (!SelfDecl)
384  return false;
385 
386  SVal SelfVal = State->getSVal(State->getRegion(SelfDecl, LocCtxt));
387 
388  const ObjCObjectPointerType *SelfType =
389  dyn_cast<ObjCObjectPointerType>(SelfDecl->getType());
390  if (!SelfType)
391  return false;
392 
393  const ObjCInterfaceDecl *ID = SelfType->getInterfaceDecl();
394  if (!ID)
395  return false;
396 
397  for (const auto *IvarDecl : ID->ivars()) {
398  SVal LV = State->getLValue(IvarDecl, SelfVal);
399  if (checkValueAtLValForInvariantViolation(State, LV, IvarDecl->getType())) {
400  return true;
401  }
402  }
403  return false;
404 }
405 
406 static bool checkInvariantViolation(ProgramStateRef State, ExplodedNode *N,
407  CheckerContext &C) {
408  if (State->get<InvariantViolated>())
409  return true;
410 
411  const LocationContext *LocCtxt = C.getLocationContext();
412  const Decl *D = LocCtxt->getDecl();
413  if (!D)
414  return false;
415 
416  ArrayRef<ParmVarDecl*> Params;
417  if (const auto *BD = dyn_cast<BlockDecl>(D))
418  Params = BD->parameters();
419  else if (const auto *FD = dyn_cast<FunctionDecl>(D))
420  Params = FD->parameters();
421  else if (const auto *MD = dyn_cast<ObjCMethodDecl>(D))
422  Params = MD->parameters();
423  else
424  return false;
425 
426  if (checkParamsForPreconditionViolation(Params, State, LocCtxt) ||
427  checkSelfIvarsForInvariantViolation(State, LocCtxt)) {
428  if (!N->isSink())
429  C.addTransition(State->set<InvariantViolated>(true), N);
430  return true;
431  }
432  return false;
433 }
434 
435 void NullabilityChecker::reportBugIfInvariantHolds(StringRef Msg,
436  ErrorKind Error, ExplodedNode *N, const MemRegion *Region,
437  CheckerContext &C, const Stmt *ValueExpr, bool SuppressPath) const {
438  ProgramStateRef OriginalState = N->getState();
439 
440  if (checkInvariantViolation(OriginalState, N, C))
441  return;
442  if (SuppressPath) {
443  OriginalState = OriginalState->set<InvariantViolated>(true);
444  N = C.addTransition(OriginalState, N);
445  }
446 
447  reportBug(Msg, Error, N, Region, C.getBugReporter(), ValueExpr);
448 }
449 
450 /// Cleaning up the program state.
451 void NullabilityChecker::checkDeadSymbols(SymbolReaper &SR,
452  CheckerContext &C) const {
453  ProgramStateRef State = C.getState();
454  NullabilityMapTy Nullabilities = State->get<NullabilityMap>();
455  for (NullabilityMapTy::iterator I = Nullabilities.begin(),
456  E = Nullabilities.end();
457  I != E; ++I) {
458  const auto *Region = I->first->getAs<SymbolicRegion>();
459  assert(Region && "Non-symbolic region is tracked.");
460  if (SR.isDead(Region->getSymbol())) {
461  State = State->remove<NullabilityMap>(I->first);
462  }
463  }
464  // When one of the nonnull arguments are constrained to be null, nullability
465  // preconditions are violated. It is not enough to check this only when we
466  // actually report an error, because at that time interesting symbols might be
467  // reaped.
468  if (checkInvariantViolation(State, C.getPredecessor(), C))
469  return;
470  C.addTransition(State);
471 }
472 
473 /// This callback triggers when a pointer is dereferenced and the analyzer does
474 /// not know anything about the value of that pointer. When that pointer is
475 /// nullable, this code emits a warning.
476 void NullabilityChecker::checkEvent(ImplicitNullDerefEvent Event) const {
477  if (Event.SinkNode->getState()->get<InvariantViolated>())
478  return;
479 
480  const MemRegion *Region =
481  getTrackRegion(Event.Location, /*CheckSuperRegion=*/true);
482  if (!Region)
483  return;
484 
485  ProgramStateRef State = Event.SinkNode->getState();
486  const NullabilityState *TrackedNullability =
487  State->get<NullabilityMap>(Region);
488 
489  if (!TrackedNullability)
490  return;
491 
492  if (Filter.CheckNullableDereferenced &&
493  TrackedNullability->getValue() == Nullability::Nullable) {
494  BugReporter &BR = *Event.BR;
495  // Do not suppress errors on defensive code paths, because dereferencing
496  // a nullable pointer is always an error.
497  if (Event.IsDirectDereference)
498  reportBug("Nullable pointer is dereferenced",
499  ErrorKind::NullableDereferenced, Event.SinkNode, Region, BR);
500  else {
501  reportBug("Nullable pointer is passed to a callee that requires a "
502  "non-null", ErrorKind::NullablePassedToNonnull,
503  Event.SinkNode, Region, BR);
504  }
505  }
506 }
507 
508 /// Find the outermost subexpression of E that is not an implicit cast.
509 /// This looks through the implicit casts to _Nonnull that ARC adds to
510 /// return expressions of ObjC types when the return type of the function or
511 /// method is non-null but the express is not.
512 static const Expr *lookThroughImplicitCasts(const Expr *E) {
513  assert(E);
514 
515  while (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) {
516  E = ICE->getSubExpr();
517  }
518 
519  return E;
520 }
521 
522 /// This method check when nullable pointer or null value is returned from a
523 /// function that has nonnull return type.
524 void NullabilityChecker::checkPreStmt(const ReturnStmt *S,
525  CheckerContext &C) const {
526  auto RetExpr = S->getRetValue();
527  if (!RetExpr)
528  return;
529 
530  if (!RetExpr->getType()->isAnyPointerType())
531  return;
532 
533  ProgramStateRef State = C.getState();
534  if (State->get<InvariantViolated>())
535  return;
536 
537  auto RetSVal = C.getSVal(S).getAs<DefinedOrUnknownSVal>();
538  if (!RetSVal)
539  return;
540 
541  bool InSuppressedMethodFamily = false;
542 
543  QualType RequiredRetType;
544  AnalysisDeclContext *DeclCtxt =
545  C.getLocationContext()->getAnalysisDeclContext();
546  const Decl *D = DeclCtxt->getDecl();
547  if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
548  // HACK: This is a big hammer to avoid warning when there are defensive
549  // nil checks in -init and -copy methods. We should add more sophisticated
550  // logic here to suppress on common defensive idioms but still
551  // warn when there is a likely problem.
552  ObjCMethodFamily Family = MD->getMethodFamily();
553  if (OMF_init == Family || OMF_copy == Family || OMF_mutableCopy == Family)
554  InSuppressedMethodFamily = true;
555 
556  RequiredRetType = MD->getReturnType();
557  } else if (auto *FD = dyn_cast<FunctionDecl>(D)) {
558  RequiredRetType = FD->getReturnType();
559  } else {
560  return;
561  }
562 
563  NullConstraint Nullness = getNullConstraint(*RetSVal, State);
564 
565  Nullability RequiredNullability = getNullabilityAnnotation(RequiredRetType);
566 
567  // If the returned value is null but the type of the expression
568  // generating it is nonnull then we will suppress the diagnostic.
569  // This enables explicit suppression when returning a nil literal in a
570  // function with a _Nonnull return type:
571  // return (NSString * _Nonnull)0;
572  Nullability RetExprTypeLevelNullability =
574 
575  bool NullReturnedFromNonNull = (RequiredNullability == Nullability::Nonnull &&
576  Nullness == NullConstraint::IsNull);
577  if (Filter.CheckNullReturnedFromNonnull &&
578  NullReturnedFromNonNull &&
579  RetExprTypeLevelNullability != Nullability::Nonnull &&
580  !InSuppressedMethodFamily &&
581  C.getLocationContext()->inTopFrame()) {
582  static CheckerProgramPointTag Tag(this, "NullReturnedFromNonnull");
583  ExplodedNode *N = C.generateErrorNode(State, &Tag);
584  if (!N)
585  return;
586 
587  SmallString<256> SBuf;
588  llvm::raw_svector_ostream OS(SBuf);
589  OS << (RetExpr->getType()->isObjCObjectPointerType() ? "nil" : "Null");
590  OS << " returned from a " << C.getDeclDescription(D) <<
591  " that is expected to return a non-null value";
592  reportBugIfInvariantHolds(OS.str(),
593  ErrorKind::NilReturnedToNonnull, N, nullptr, C,
594  RetExpr);
595  return;
596  }
597 
598  // If null was returned from a non-null function, mark the nullability
599  // invariant as violated even if the diagnostic was suppressed.
600  if (NullReturnedFromNonNull) {
601  State = State->set<InvariantViolated>(true);
602  C.addTransition(State);
603  return;
604  }
605 
606  const MemRegion *Region = getTrackRegion(*RetSVal);
607  if (!Region)
608  return;
609 
610  const NullabilityState *TrackedNullability =
611  State->get<NullabilityMap>(Region);
612  if (TrackedNullability) {
613  Nullability TrackedNullabValue = TrackedNullability->getValue();
614  if (Filter.CheckNullableReturnedFromNonnull &&
615  Nullness != NullConstraint::IsNotNull &&
616  TrackedNullabValue == Nullability::Nullable &&
617  RequiredNullability == Nullability::Nonnull) {
618  static CheckerProgramPointTag Tag(this, "NullableReturnedFromNonnull");
619  ExplodedNode *N = C.addTransition(State, C.getPredecessor(), &Tag);
620 
621  SmallString<256> SBuf;
622  llvm::raw_svector_ostream OS(SBuf);
623  OS << "Nullable pointer is returned from a " << C.getDeclDescription(D) <<
624  " that is expected to return a non-null value";
625 
626  reportBugIfInvariantHolds(OS.str(),
627  ErrorKind::NullableReturnedToNonnull, N,
628  Region, C);
629  }
630  return;
631  }
632  if (RequiredNullability == Nullability::Nullable) {
633  State = State->set<NullabilityMap>(Region,
634  NullabilityState(RequiredNullability,
635  S));
636  C.addTransition(State);
637  }
638 }
639 
640 /// This callback warns when a nullable pointer or a null value is passed to a
641 /// function that expects its argument to be nonnull.
642 void NullabilityChecker::checkPreCall(const CallEvent &Call,
643  CheckerContext &C) const {
644  if (!Call.getDecl())
645  return;
646 
647  ProgramStateRef State = C.getState();
648  if (State->get<InvariantViolated>())
649  return;
650 
651  ProgramStateRef OrigState = State;
652 
653  unsigned Idx = 0;
654  for (const ParmVarDecl *Param : Call.parameters()) {
655  if (Param->isParameterPack())
656  break;
657 
658  if (Idx >= Call.getNumArgs())
659  break;
660 
661  const Expr *ArgExpr = Call.getArgExpr(Idx);
662  auto ArgSVal = Call.getArgSVal(Idx++).getAs<DefinedOrUnknownSVal>();
663  if (!ArgSVal)
664  continue;
665 
666  if (!Param->getType()->isAnyPointerType() &&
667  !Param->getType()->isReferenceType())
668  continue;
669 
670  NullConstraint Nullness = getNullConstraint(*ArgSVal, State);
671 
672  Nullability RequiredNullability =
673  getNullabilityAnnotation(Param->getType());
674  Nullability ArgExprTypeLevelNullability =
675  getNullabilityAnnotation(ArgExpr->getType());
676 
677  unsigned ParamIdx = Param->getFunctionScopeIndex() + 1;
678 
679  if (Filter.CheckNullPassedToNonnull && Nullness == NullConstraint::IsNull &&
680  ArgExprTypeLevelNullability != Nullability::Nonnull &&
681  RequiredNullability == Nullability::Nonnull &&
682  isDiagnosableCall(Call)) {
683  ExplodedNode *N = C.generateErrorNode(State);
684  if (!N)
685  return;
686 
687  SmallString<256> SBuf;
688  llvm::raw_svector_ostream OS(SBuf);
689  OS << (Param->getType()->isObjCObjectPointerType() ? "nil" : "Null");
690  OS << " passed to a callee that requires a non-null " << ParamIdx
691  << llvm::getOrdinalSuffix(ParamIdx) << " parameter";
692  reportBugIfInvariantHolds(OS.str(), ErrorKind::NilPassedToNonnull, N,
693  nullptr, C,
694  ArgExpr, /*SuppressPath=*/false);
695  return;
696  }
697 
698  const MemRegion *Region = getTrackRegion(*ArgSVal);
699  if (!Region)
700  continue;
701 
702  const NullabilityState *TrackedNullability =
703  State->get<NullabilityMap>(Region);
704 
705  if (TrackedNullability) {
706  if (Nullness == NullConstraint::IsNotNull ||
707  TrackedNullability->getValue() != Nullability::Nullable)
708  continue;
709 
710  if (Filter.CheckNullablePassedToNonnull &&
711  RequiredNullability == Nullability::Nonnull &&
712  isDiagnosableCall(Call)) {
713  ExplodedNode *N = C.addTransition(State);
714  SmallString<256> SBuf;
715  llvm::raw_svector_ostream OS(SBuf);
716  OS << "Nullable pointer is passed to a callee that requires a non-null "
717  << ParamIdx << llvm::getOrdinalSuffix(ParamIdx) << " parameter";
718  reportBugIfInvariantHolds(OS.str(),
719  ErrorKind::NullablePassedToNonnull, N,
720  Region, C, ArgExpr, /*SuppressPath=*/true);
721  return;
722  }
723  if (Filter.CheckNullableDereferenced &&
724  Param->getType()->isReferenceType()) {
725  ExplodedNode *N = C.addTransition(State);
726  reportBugIfInvariantHolds("Nullable pointer is dereferenced",
727  ErrorKind::NullableDereferenced, N, Region,
728  C, ArgExpr, /*SuppressPath=*/true);
729  return;
730  }
731  continue;
732  }
733  // No tracked nullability yet.
734  if (ArgExprTypeLevelNullability != Nullability::Nullable)
735  continue;
736  State = State->set<NullabilityMap>(
737  Region, NullabilityState(ArgExprTypeLevelNullability, ArgExpr));
738  }
739  if (State != OrigState)
740  C.addTransition(State);
741 }
742 
743 /// Suppress the nullability warnings for some functions.
744 void NullabilityChecker::checkPostCall(const CallEvent &Call,
745  CheckerContext &C) const {
746  auto Decl = Call.getDecl();
747  if (!Decl)
748  return;
749  // ObjC Messages handles in a different callback.
750  if (Call.getKind() == CE_ObjCMessage)
751  return;
752  const FunctionType *FuncType = Decl->getFunctionType();
753  if (!FuncType)
754  return;
755  QualType ReturnType = FuncType->getReturnType();
756  if (!ReturnType->isAnyPointerType())
757  return;
758  ProgramStateRef State = C.getState();
759  if (State->get<InvariantViolated>())
760  return;
761 
762  const MemRegion *Region = getTrackRegion(Call.getReturnValue());
763  if (!Region)
764  return;
765 
766  // CG headers are misannotated. Do not warn for symbols that are the results
767  // of CG calls.
768  const SourceManager &SM = C.getSourceManager();
769  StringRef FilePath = SM.getFilename(SM.getSpellingLoc(Decl->getBeginLoc()));
770  if (llvm::sys::path::filename(FilePath).startswith("CG")) {
771  State = State->set<NullabilityMap>(Region, Nullability::Contradicted);
772  C.addTransition(State);
773  return;
774  }
775 
776  const NullabilityState *TrackedNullability =
777  State->get<NullabilityMap>(Region);
778 
779  if (!TrackedNullability &&
781  State = State->set<NullabilityMap>(Region, Nullability::Nullable);
782  C.addTransition(State);
783  }
784 }
785 
788  if (M.isReceiverSelfOrSuper()) {
789  // For super and super class receivers we assume that the receiver is
790  // nonnull.
791  return Nullability::Nonnull;
792  }
793  // Otherwise look up nullability in the state.
794  SVal Receiver = M.getReceiverSVal();
795  if (auto DefOrUnknown = Receiver.getAs<DefinedOrUnknownSVal>()) {
796  // If the receiver is constrained to be nonnull, assume that it is nonnull
797  // regardless of its type.
798  NullConstraint Nullness = getNullConstraint(*DefOrUnknown, State);
799  if (Nullness == NullConstraint::IsNotNull)
800  return Nullability::Nonnull;
801  }
802  auto ValueRegionSVal = Receiver.getAs<loc::MemRegionVal>();
803  if (ValueRegionSVal) {
804  const MemRegion *SelfRegion = ValueRegionSVal->getRegion();
805  assert(SelfRegion);
806 
807  const NullabilityState *TrackedSelfNullability =
808  State->get<NullabilityMap>(SelfRegion);
809  if (TrackedSelfNullability)
810  return TrackedSelfNullability->getValue();
811  }
813 }
814 
815 /// Calculate the nullability of the result of a message expr based on the
816 /// nullability of the receiver, the nullability of the return value, and the
817 /// constraints.
818 void NullabilityChecker::checkPostObjCMessage(const ObjCMethodCall &M,
819  CheckerContext &C) const {
820  auto Decl = M.getDecl();
821  if (!Decl)
822  return;
823  QualType RetType = Decl->getReturnType();
824  if (!RetType->isAnyPointerType())
825  return;
826 
827  ProgramStateRef State = C.getState();
828  if (State->get<InvariantViolated>())
829  return;
830 
831  const MemRegion *ReturnRegion = getTrackRegion(M.getReturnValue());
832  if (!ReturnRegion)
833  return;
834 
835  auto Interface = Decl->getClassInterface();
836  auto Name = Interface ? Interface->getName() : "";
837  // In order to reduce the noise in the diagnostics generated by this checker,
838  // some framework and programming style based heuristics are used. These
839  // heuristics are for Cocoa APIs which have NS prefix.
840  if (Name.startswith("NS")) {
841  // Developers rely on dynamic invariants such as an item should be available
842  // in a collection, or a collection is not empty often. Those invariants can
843  // not be inferred by any static analysis tool. To not to bother the users
844  // with too many false positives, every item retrieval function should be
845  // ignored for collections. The instance methods of dictionaries in Cocoa
846  // are either item retrieval related or not interesting nullability wise.
847  // Using this fact, to keep the code easier to read just ignore the return
848  // value of every instance method of dictionaries.
849  if (M.isInstanceMessage() && Name.contains("Dictionary")) {
850  State =
851  State->set<NullabilityMap>(ReturnRegion, Nullability::Contradicted);
852  C.addTransition(State);
853  return;
854  }
855  // For similar reasons ignore some methods of Cocoa arrays.
856  StringRef FirstSelectorSlot = M.getSelector().getNameForSlot(0);
857  if (Name.contains("Array") &&
858  (FirstSelectorSlot == "firstObject" ||
859  FirstSelectorSlot == "lastObject")) {
860  State =
861  State->set<NullabilityMap>(ReturnRegion, Nullability::Contradicted);
862  C.addTransition(State);
863  return;
864  }
865 
866  // Encoding related methods of string should not fail when lossless
867  // encodings are used. Using lossless encodings is so frequent that ignoring
868  // this class of methods reduced the emitted diagnostics by about 30% on
869  // some projects (and all of that was false positives).
870  if (Name.contains("String")) {
871  for (auto Param : M.parameters()) {
872  if (Param->getName() == "encoding") {
873  State = State->set<NullabilityMap>(ReturnRegion,
875  C.addTransition(State);
876  return;
877  }
878  }
879  }
880  }
881 
882  const ObjCMessageExpr *Message = M.getOriginExpr();
883  Nullability SelfNullability = getReceiverNullability(M, State);
884 
885  const NullabilityState *NullabilityOfReturn =
886  State->get<NullabilityMap>(ReturnRegion);
887 
888  if (NullabilityOfReturn) {
889  // When we have a nullability tracked for the return value, the nullability
890  // of the expression will be the most nullable of the receiver and the
891  // return value.
892  Nullability RetValTracked = NullabilityOfReturn->getValue();
893  Nullability ComputedNullab =
894  getMostNullable(RetValTracked, SelfNullability);
895  if (ComputedNullab != RetValTracked &&
896  ComputedNullab != Nullability::Unspecified) {
897  const Stmt *NullabilitySource =
898  ComputedNullab == RetValTracked
899  ? NullabilityOfReturn->getNullabilitySource()
900  : Message->getInstanceReceiver();
901  State = State->set<NullabilityMap>(
902  ReturnRegion, NullabilityState(ComputedNullab, NullabilitySource));
903  C.addTransition(State);
904  }
905  return;
906  }
907 
908  // No tracked information. Use static type information for return value.
909  Nullability RetNullability = getNullabilityAnnotation(RetType);
910 
911  // Properties might be computed. For this reason the static analyzer creates a
912  // new symbol each time an unknown property is read. To avoid false pozitives
913  // do not treat unknown properties as nullable, even when they explicitly
914  // marked nullable.
915  if (M.getMessageKind() == OCM_PropertyAccess && !C.wasInlined)
916  RetNullability = Nullability::Nonnull;
917 
918  Nullability ComputedNullab = getMostNullable(RetNullability, SelfNullability);
919  if (ComputedNullab == Nullability::Nullable) {
920  const Stmt *NullabilitySource = ComputedNullab == RetNullability
921  ? Message
922  : Message->getInstanceReceiver();
923  State = State->set<NullabilityMap>(
924  ReturnRegion, NullabilityState(ComputedNullab, NullabilitySource));
925  C.addTransition(State);
926  }
927 }
928 
929 /// Explicit casts are trusted. If there is a disagreement in the nullability
930 /// annotations in the destination and the source or '0' is casted to nonnull
931 /// track the value as having contraditory nullability. This will allow users to
932 /// suppress warnings.
933 void NullabilityChecker::checkPostStmt(const ExplicitCastExpr *CE,
934  CheckerContext &C) const {
935  QualType OriginType = CE->getSubExpr()->getType();
936  QualType DestType = CE->getType();
937  if (!OriginType->isAnyPointerType())
938  return;
939  if (!DestType->isAnyPointerType())
940  return;
941 
942  ProgramStateRef State = C.getState();
943  if (State->get<InvariantViolated>())
944  return;
945 
946  Nullability DestNullability = getNullabilityAnnotation(DestType);
947 
948  // No explicit nullability in the destination type, so this cast does not
949  // change the nullability.
950  if (DestNullability == Nullability::Unspecified)
951  return;
952 
953  auto RegionSVal = C.getSVal(CE).getAs<DefinedOrUnknownSVal>();
954  const MemRegion *Region = getTrackRegion(*RegionSVal);
955  if (!Region)
956  return;
957 
958  // When 0 is converted to nonnull mark it as contradicted.
959  if (DestNullability == Nullability::Nonnull) {
960  NullConstraint Nullness = getNullConstraint(*RegionSVal, State);
961  if (Nullness == NullConstraint::IsNull) {
962  State = State->set<NullabilityMap>(Region, Nullability::Contradicted);
963  C.addTransition(State);
964  return;
965  }
966  }
967 
968  const NullabilityState *TrackedNullability =
969  State->get<NullabilityMap>(Region);
970 
971  if (!TrackedNullability) {
972  if (DestNullability != Nullability::Nullable)
973  return;
974  State = State->set<NullabilityMap>(Region,
975  NullabilityState(DestNullability, CE));
976  C.addTransition(State);
977  return;
978  }
979 
980  if (TrackedNullability->getValue() != DestNullability &&
981  TrackedNullability->getValue() != Nullability::Contradicted) {
982  State = State->set<NullabilityMap>(Region, Nullability::Contradicted);
983  C.addTransition(State);
984  }
985 }
986 
987 /// For a given statement performing a bind, attempt to syntactically
988 /// match the expression resulting in the bound value.
989 static const Expr * matchValueExprForBind(const Stmt *S) {
990  // For `x = e` the value expression is the right-hand side.
991  if (auto *BinOp = dyn_cast<BinaryOperator>(S)) {
992  if (BinOp->getOpcode() == BO_Assign)
993  return BinOp->getRHS();
994  }
995 
996  // For `int x = e` the value expression is the initializer.
997  if (auto *DS = dyn_cast<DeclStmt>(S)) {
998  if (DS->isSingleDecl()) {
999  auto *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
1000  if (!VD)
1001  return nullptr;
1002 
1003  if (const Expr *Init = VD->getInit())
1004  return Init;
1005  }
1006  }
1007 
1008  return nullptr;
1009 }
1010 
1011 /// Returns true if \param S is a DeclStmt for a local variable that
1012 /// ObjC automated reference counting initialized with zero.
1013 static bool isARCNilInitializedLocal(CheckerContext &C, const Stmt *S) {
1014  // We suppress diagnostics for ARC zero-initialized _Nonnull locals. This
1015  // prevents false positives when a _Nonnull local variable cannot be
1016  // initialized with an initialization expression:
1017  // NSString * _Nonnull s; // no-warning
1018  // @autoreleasepool {
1019  // s = ...
1020  // }
1021  //
1022  // FIXME: We should treat implicitly zero-initialized _Nonnull locals as
1023  // uninitialized in Sema's UninitializedValues analysis to warn when a use of
1024  // the zero-initialized definition will unexpectedly yield nil.
1025 
1026  // Locals are only zero-initialized when automated reference counting
1027  // is turned on.
1028  if (!C.getASTContext().getLangOpts().ObjCAutoRefCount)
1029  return false;
1030 
1031  auto *DS = dyn_cast<DeclStmt>(S);
1032  if (!DS || !DS->isSingleDecl())
1033  return false;
1034 
1035  auto *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
1036  if (!VD)
1037  return false;
1038 
1039  // Sema only zero-initializes locals with ObjCLifetimes.
1040  if(!VD->getType().getQualifiers().hasObjCLifetime())
1041  return false;
1042 
1043  const Expr *Init = VD->getInit();
1044  assert(Init && "ObjC local under ARC without initializer");
1045 
1046  // Return false if the local is explicitly initialized (e.g., with '= nil').
1047  if (!isa<ImplicitValueInitExpr>(Init))
1048  return false;
1049 
1050  return true;
1051 }
1052 
1053 /// Propagate the nullability information through binds and warn when nullable
1054 /// pointer or null symbol is assigned to a pointer with a nonnull type.
1055 void NullabilityChecker::checkBind(SVal L, SVal V, const Stmt *S,
1056  CheckerContext &C) const {
1057  const TypedValueRegion *TVR =
1058  dyn_cast_or_null<TypedValueRegion>(L.getAsRegion());
1059  if (!TVR)
1060  return;
1061 
1062  QualType LocType = TVR->getValueType();
1063  if (!LocType->isAnyPointerType())
1064  return;
1065 
1066  ProgramStateRef State = C.getState();
1067  if (State->get<InvariantViolated>())
1068  return;
1069 
1070  auto ValDefOrUnknown = V.getAs<DefinedOrUnknownSVal>();
1071  if (!ValDefOrUnknown)
1072  return;
1073 
1074  NullConstraint RhsNullness = getNullConstraint(*ValDefOrUnknown, State);
1075 
1076  Nullability ValNullability = Nullability::Unspecified;
1077  if (SymbolRef Sym = ValDefOrUnknown->getAsSymbol())
1078  ValNullability = getNullabilityAnnotation(Sym->getType());
1079 
1080  Nullability LocNullability = getNullabilityAnnotation(LocType);
1081 
1082  // If the type of the RHS expression is nonnull, don't warn. This
1083  // enables explicit suppression with a cast to nonnull.
1084  Nullability ValueExprTypeLevelNullability = Nullability::Unspecified;
1085  const Expr *ValueExpr = matchValueExprForBind(S);
1086  if (ValueExpr) {
1087  ValueExprTypeLevelNullability =
1088  getNullabilityAnnotation(lookThroughImplicitCasts(ValueExpr)->getType());
1089  }
1090 
1091  bool NullAssignedToNonNull = (LocNullability == Nullability::Nonnull &&
1092  RhsNullness == NullConstraint::IsNull);
1093  if (Filter.CheckNullPassedToNonnull &&
1094  NullAssignedToNonNull &&
1095  ValNullability != Nullability::Nonnull &&
1096  ValueExprTypeLevelNullability != Nullability::Nonnull &&
1097  !isARCNilInitializedLocal(C, S)) {
1098  static CheckerProgramPointTag Tag(this, "NullPassedToNonnull");
1099  ExplodedNode *N = C.generateErrorNode(State, &Tag);
1100  if (!N)
1101  return;
1102 
1103 
1104  const Stmt *ValueStmt = S;
1105  if (ValueExpr)
1106  ValueStmt = ValueExpr;
1107 
1108  SmallString<256> SBuf;
1109  llvm::raw_svector_ostream OS(SBuf);
1110  OS << (LocType->isObjCObjectPointerType() ? "nil" : "Null");
1111  OS << " assigned to a pointer which is expected to have non-null value";
1112  reportBugIfInvariantHolds(OS.str(),
1113  ErrorKind::NilAssignedToNonnull, N, nullptr, C,
1114  ValueStmt);
1115  return;
1116  }
1117 
1118  // If null was returned from a non-null function, mark the nullability
1119  // invariant as violated even if the diagnostic was suppressed.
1120  if (NullAssignedToNonNull) {
1121  State = State->set<InvariantViolated>(true);
1122  C.addTransition(State);
1123  return;
1124  }
1125 
1126  // Intentionally missing case: '0' is bound to a reference. It is handled by
1127  // the DereferenceChecker.
1128 
1129  const MemRegion *ValueRegion = getTrackRegion(*ValDefOrUnknown);
1130  if (!ValueRegion)
1131  return;
1132 
1133  const NullabilityState *TrackedNullability =
1134  State->get<NullabilityMap>(ValueRegion);
1135 
1136  if (TrackedNullability) {
1137  if (RhsNullness == NullConstraint::IsNotNull ||
1138  TrackedNullability->getValue() != Nullability::Nullable)
1139  return;
1140  if (Filter.CheckNullablePassedToNonnull &&
1141  LocNullability == Nullability::Nonnull) {
1142  static CheckerProgramPointTag Tag(this, "NullablePassedToNonnull");
1143  ExplodedNode *N = C.addTransition(State, C.getPredecessor(), &Tag);
1144  reportBugIfInvariantHolds("Nullable pointer is assigned to a pointer "
1145  "which is expected to have non-null value",
1146  ErrorKind::NullableAssignedToNonnull, N,
1147  ValueRegion, C);
1148  }
1149  return;
1150  }
1151 
1152  const auto *BinOp = dyn_cast<BinaryOperator>(S);
1153 
1154  if (ValNullability == Nullability::Nullable) {
1155  // Trust the static information of the value more than the static
1156  // information on the location.
1157  const Stmt *NullabilitySource = BinOp ? BinOp->getRHS() : S;
1158  State = State->set<NullabilityMap>(
1159  ValueRegion, NullabilityState(ValNullability, NullabilitySource));
1160  C.addTransition(State);
1161  return;
1162  }
1163 
1164  if (LocNullability == Nullability::Nullable) {
1165  const Stmt *NullabilitySource = BinOp ? BinOp->getLHS() : S;
1166  State = State->set<NullabilityMap>(
1167  ValueRegion, NullabilityState(LocNullability, NullabilitySource));
1168  C.addTransition(State);
1169  }
1170 }
1171 
1172 void NullabilityChecker::printState(raw_ostream &Out, ProgramStateRef State,
1173  const char *NL, const char *Sep) const {
1174 
1175  NullabilityMapTy B = State->get<NullabilityMap>();
1176 
1177  if (State->get<InvariantViolated>())
1178  Out << Sep << NL
1179  << "Nullability invariant was violated, warnings suppressed." << NL;
1180 
1181  if (B.isEmpty())
1182  return;
1183 
1184  if (!State->get<InvariantViolated>())
1185  Out << Sep << NL;
1186 
1187  for (NullabilityMapTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
1188  Out << I->first << " : ";
1189  I->second.print(Out);
1190  Out << NL;
1191  }
1192 }
1193 
1194 void ento::registerNullabilityBase(CheckerManager &mgr) {
1195  mgr.registerChecker<NullabilityChecker>();
1196 }
1197 
1198 bool ento::shouldRegisterNullabilityBase(const LangOptions &LO) {
1199  return true;
1200 }
1201 
1202 #define REGISTER_CHECKER(name, trackingRequired) \
1203  void ento::register##name##Checker(CheckerManager &mgr) { \
1204  NullabilityChecker *checker = mgr.getChecker<NullabilityChecker>(); \
1205  checker->Filter.Check##name = true; \
1206  checker->Filter.CheckName##name = mgr.getCurrentCheckName(); \
1207  checker->NeedTracking = checker->NeedTracking || trackingRequired; \
1208  checker->NoDiagnoseCallsToSystemHeaders = \
1209  checker->NoDiagnoseCallsToSystemHeaders || \
1210  mgr.getAnalyzerOptions().getCheckerBooleanOption( \
1211  checker, "NoDiagnoseCallsToSystemHeaders", true); \
1212  } \
1213  \
1214  bool ento::shouldRegister##name##Checker(const LangOptions &LO) { \
1215  return true; \
1216  }
1217 
1218 // The checks are likely to be turned on by default and it is possible to do
1219 // them without tracking any nullability related information. As an optimization
1220 // no nullability information will be tracked when only these two checks are
1221 // enables.
1222 REGISTER_CHECKER(NullPassedToNonnull, false)
1223 REGISTER_CHECKER(NullReturnedFromNonnull, false)
1224 
1225 REGISTER_CHECKER(NullableDereferenced, true)
1226 REGISTER_CHECKER(NullablePassedToNonnull, true)
1227 REGISTER_CHECKER(NullableReturnedFromNonnull, true)
SVal getReceiverSVal() const
Returns the value of the receiver at the time of this call.
Definition: CallEvent.cpp:973
static bool checkParamsForPreconditionViolation(ArrayRef< ParmVarDecl *> Params, ProgramStateRef State, const LocationContext *LocCtxt)
A (possibly-)qualified type.
Definition: Type.h:643
bool operator==(CanQual< T > x, CanQual< U > y)
const SymExpr * SymbolRef
Stmt - This represents one statement.
Definition: Stmt.h:66
FunctionType - C99 6.7.5.3 - Function Declarators.
Definition: Type.h:3387
static bool checkValueAtLValForInvariantViolation(ProgramStateRef State, SVal LV, QualType T)
Returns true when the value stored at the given location has been constrained to null after being pas...
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:88
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: DeclBase.h:421
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
ivar_range ivars() const
Definition: DeclObjC.h:1457
static Nullability getReceiverNullability(const ObjCMethodCall &M, ProgramStateRef State)
Represents a variable declaration or definition.
Definition: Decl.h:812
ObjCMethodDecl - Represents an instance or class method declaration.
Definition: DeclObjC.h:138
Represents a parameter to a function.
Definition: Decl.h:1564
static NullConstraint getNullConstraint(DefinedOrUnknownSVal Val, ProgramStateRef State)
Represents a statement that could possibly have a value and type.
Definition: Stmt.h:1691
LineState State
ObjCMethodFamily
A family of Objective-C methods.
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: Stmt.cpp:263
AnalysisDeclContext contains the context data for the function or method under analysis.
Expr * getSubExpr()
Definition: Expr.h:3173
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:49
Represents any expression that calls an Objective-C method.
Definition: CallEvent.h:937
const ImplicitParamDecl * getSelfDecl() const
A builtin binary operation expression such as "x + y" or "x <= y".
Definition: Expr.h:3405
SourceLocation getSpellingLoc(SourceLocation Loc) const
Given a SourceLocation object, return the spelling location referenced by the ID. ...
Represents an ObjC class declaration.
Definition: DeclObjC.h:1171
bool isReceiverSelfOrSuper() const
Checks if the receiver refers to &#39;self&#39; or &#39;super&#39;.
Definition: CallEvent.cpp:989
ArrayRef< ParmVarDecl * > parameters() const override
Definition: CallEvent.cpp:933
const FunctionType * getFunctionType(bool BlocksToo=true) const
Looks through the Decl&#39;s underlying type to extract a FunctionType when possible. ...
Definition: DeclBase.cpp:951
A single parameter index whose accessors require each use to make explicit the parameter index encodi...
Definition: Attr.h:213
This represents one expression.
Definition: Expr.h:108
#define V(N, I)
Definition: ASTContext.h:2907
StringRef getNameForSlot(unsigned argIndex) const
Retrieve the name at a given position in the selector.
static SVal getValue(SVal val, SValBuilder &svalBuilder)
QualType getType() const
Definition: Expr.h:137
ReturnStmt - This represents a return, optionally of an expression: return; return 4;...
Definition: Stmt.h:2610
An expression that sends a message to the given Objective-C object or class.
Definition: ExprObjC.h:950
#define REGISTER_CHECKER(name, trackingRequired)
const SourceManager & SM
Definition: Format.cpp:1572
REGISTER_MAP_WITH_PROGRAMSTATE(NullabilityMap, const MemRegion *, NullabilityState) enum class NullConstraint
static const Stmt * getStmt(const ExplodedNode *N)
Given an exploded node, retrieve the statement that should be used for the diagnostic location...
StringRef getFilename(SourceLocation SpellingLoc) const
Return the filename of the file containing a SourceLocation.
llvm::cl::opt< std::string > Filter
#define false
Definition: stdbool.h:17
#define REGISTER_TRAIT_WITH_PROGRAMSTATE(Name, Type)
Declares a program state trait for type Type called Name, and introduce a type named NameTy...
QualType getReturnType() const
Definition: Type.h:3645
Expr * getRetValue()
Definition: Stmt.h:2643
static bool isARCNilInitializedLocal(CheckerContext &C, const Stmt *S)
Returns true if.
DeclStmt - Adaptor class for mixing declarations with statements and expressions. ...
Definition: Stmt.h:1203
static const Expr * lookThroughImplicitCasts(const Expr *E)
Find the outermost subexpression of E that is not an implicit cast.
const Decl * getDecl() const
bool isObjCObjectPointerType() const
Definition: Type.h:6488
bool isAnyPointerType() const
Definition: Type.h:6388
static bool checkInvariantViolation(ProgramStateRef State, ExplodedNode *N, CheckerContext &C)
static const Expr * matchValueExprForBind(const Stmt *S)
For a given statement performing a bind, attempt to syntactically match the expression resulting in t...
const ObjCMethodDecl * getDecl() const override
Definition: CallEvent.h:965
Expr * getInstanceReceiver()
Returns the object expression (receiver) for an instance message, or null for a message that is not a...
Definition: ExprObjC.h:1260
virtual const ObjCMessageExpr * getOriginExpr() const
Definition: CallEvent.h:961
Selector getSelector() const
Definition: CallEvent.h:985
Dataflow Directional Tag Classes.
Nullability getNullabilityAnnotation(QualType Type)
Get nullability annotation for a given type.
ExplicitCastExpr - An explicit cast written in the source code.
Definition: Expr.h:3308
ObjCMessageKind getMessageKind() const
Returns how the message was written in the source (property access, subscript, or explicit message se...
Definition: CallEvent.cpp:1033
const Decl * getDecl() const
Represents a pointer to an Objective C object.
Definition: Type.h:5864
bool isInstanceMessage() const
Definition: CallEvent.h:977
Indicates that the tracking object is a descendant of a referenced-counted OSObject, used in the Darwin kernel.
ObjCInterfaceDecl * getInterfaceDecl() const
If this pointer points to an Objective @interface type, gets the declaration for that interface...
Definition: Type.h:5920
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:14425
__DEVICE__ int min(int __a, int __b)
static bool checkSelfIvarsForInvariantViolation(ProgramStateRef State, const LocationContext *LocCtxt)
QualType getType() const
Definition: Decl.h:647
#define true
Definition: stdbool.h:16
This class handles loading and caching of source files into memory.