1// MoveChecker.cpp - Check use of moved-from objects. - C++ ---------------===//
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 defines checker which checks for potential misuses of a moved-from
10// object. That means method calls on the object or copying it in moved-from
11// state.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/AST/Attr.h"
16#include "clang/AST/ExprCXX.h"
17#include "clang/Driver/DriverDiagnostic.h"
18#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
19#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
20#include "clang/StaticAnalyzer/Core/Checker.h"
21#include "clang/StaticAnalyzer/Core/CheckerManager.h"
22#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
23#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
24#include "llvm/ADT/StringSet.h"
25
26using namespace clang;
27using namespace ento;
28
29namespace {
30struct RegionState {
31private:
32  enum Kind { Moved, Reported } K;
33  RegionState(Kind InK) : K(InK) {}
34
35public:
36  bool isReported() const { return K == Reported; }
37  bool isMoved() const { return K == Moved; }
38
39  static RegionState getReported() { return RegionState(Reported); }
40  static RegionState getMoved() { return RegionState(Moved); }
41
42  bool operator==(const RegionState &X) const { return K == X.K; }
43  void Profile(llvm::FoldingSetNodeID &ID) const { ID.AddInteger(K); }
44};
45} // end of anonymous namespace
46
47namespace {
48class MoveChecker
49    : public Checker<check::PreCall, check::PostCall,
50                     check::DeadSymbols, check::RegionChanges> {
51public:
52  void checkPreCall(const CallEvent &MC, CheckerContext &C) const;
53  void checkPostCall(const CallEvent &MC, CheckerContext &C) const;
54  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
55  ProgramStateRef
56  checkRegionChanges(ProgramStateRef State,
57                     const InvalidatedSymbols *Invalidated,
58                     ArrayRef<const MemRegion *> RequestedRegions,
59                     ArrayRef<const MemRegion *> InvalidatedRegions,
60                     const LocationContext *LCtx, const CallEvent *Call) const;
61  void printState(raw_ostream &Out, ProgramStateRef State,
62                  const char *NL, const char *Sep) const override;
63
64private:
65  enum MisuseKind { MK_FunCall, MK_Copy, MK_Move, MK_Dereference };
66  enum StdObjectKind { SK_NonStd, SK_Unsafe, SK_Safe, SK_SmartPtr };
67
68  enum AggressivenessKind { // In any case, don't warn after a reset.
69    AK_Invalid = -1,
70    AK_KnownsOnly = 0,      // Warn only about known move-unsafe classes.
71    AK_KnownsAndLocals = 1, // Also warn about all local objects.
72    AK_All = 2,             // Warn on any use-after-move.
73    AK_NumKinds = AK_All
74  };
75
76  static bool misuseCausesCrash(MisuseKind MK) {
77    return MK == MK_Dereference;
78  }
79
80  struct ObjectKind {
81    // Is this a local variable or a local rvalue reference?
82    bool IsLocal;
83    // Is this an STL object? If so, of what kind?
84    StdObjectKind StdKind;
85  };
86
87  // STL smart pointers are automatically re-initialized to null when moved
88  // from. So we can't warn on many methods, but we can warn when it is
89  // dereferenced, which is UB even if the resulting lvalue never gets read.
90  const llvm::StringSet<> StdSmartPtrClasses = {
91      "shared_ptr",
92      "unique_ptr",
93      "weak_ptr",
94  };
95
96  // Not all of these are entirely move-safe, but they do provide *some*
97  // guarantees, and it means that somebody is using them after move
98  // in a valid manner.
99  // TODO: We can still try to identify *unsafe* use after move,
100  // like we did with smart pointers.
101  const llvm::StringSet<> StdSafeClasses = {
102      "basic_filebuf",
103      "basic_ios",
104      "future",
105      "optional",
106      "packaged_task",
107      "promise",
108      "shared_future",
109      "shared_lock",
110      "thread",
111      "unique_lock",
112  };
113
114  // Should we bother tracking the state of the object?
115  bool shouldBeTracked(ObjectKind OK) const {
116    // In non-aggressive mode, only warn on use-after-move of local variables
117    // (or local rvalue references) and of STL objects. The former is possible
118    // because local variables (or local rvalue references) are not tempting
119    // their user to re-use the storage. The latter is possible because STL
120    // objects are known to end up in a valid but unspecified state after the
121    // move and their state-reset methods are also known, which allows us to
122    // predict precisely when use-after-move is invalid.
123    // Some STL objects are known to conform to additional contracts after move,
124    // so they are not tracked. However, smart pointers specifically are tracked
125    // because we can perform extra checking over them.
126    // In aggressive mode, warn on any use-after-move because the user has
127    // intentionally asked us to completely eliminate use-after-move
128    // in his code.
129    return (Aggressiveness == AK_All) ||
130           (Aggressiveness >= AK_KnownsAndLocals && OK.IsLocal) ||
131           OK.StdKind == SK_Unsafe || OK.StdKind == SK_SmartPtr;
132  }
133
134  // Some objects only suffer from some kinds of misuses, but we need to track
135  // them anyway because we cannot know in advance what misuse will we find.
136  bool shouldWarnAbout(ObjectKind OK, MisuseKind MK) const {
137    // Additionally, only warn on smart pointers when they are dereferenced (or
138    // local or we are aggressive).
139    return shouldBeTracked(OK) &&
140           ((Aggressiveness == AK_All) ||
141            (Aggressiveness >= AK_KnownsAndLocals && OK.IsLocal) ||
142            OK.StdKind != SK_SmartPtr || MK == MK_Dereference);
143  }
144
145  // Obtains ObjectKind of an object. Because class declaration cannot always
146  // be easily obtained from the memory region, it is supplied separately.
147  ObjectKind classifyObject(const MemRegion *MR, const CXXRecordDecl *RD) const;
148
149  // Classifies the object and dumps a user-friendly description string to
150  // the stream.
151  void explainObject(llvm::raw_ostream &OS, const MemRegion *MR,
152                     const CXXRecordDecl *RD, MisuseKind MK) const;
153
154  bool belongsTo(const CXXRecordDecl *RD, const llvm::StringSet<> &Set) const;
155
156  class MovedBugVisitor : public BugReporterVisitor {
157  public:
158    MovedBugVisitor(const MoveChecker &Chk, const MemRegion *R,
159                    const CXXRecordDecl *RD, MisuseKind MK)
160        : Chk(Chk), Region(R), RD(RD), MK(MK), Found(false) {}
161
162    void Profile(llvm::FoldingSetNodeID &ID) const override {
163      static int X = 0;
164      ID.AddPointer(&X);
165      ID.AddPointer(Region);
166      // Don't add RD because it's, in theory, uniquely determined by
167      // the region. In practice though, it's not always possible to obtain
168      // the declaration directly from the region, that's why we store it
169      // in the first place.
170    }
171
172    PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
173                                     BugReporterContext &BRC,
174                                     PathSensitiveBugReport &BR) override;
175
176  private:
177    const MoveChecker &Chk;
178    // The tracked region.
179    const MemRegion *Region;
180    // The class of the tracked object.
181    const CXXRecordDecl *RD;
182    // How exactly the object was misused.
183    const MisuseKind MK;
184    bool Found;
185  };
186
187  AggressivenessKind Aggressiveness = AK_KnownsAndLocals;
188
189public:
190  void setAggressiveness(StringRef Str, CheckerManager &Mgr) {
191    Aggressiveness =
192        llvm::StringSwitch<AggressivenessKind>(Str)
193            .Case("KnownsOnly", AK_KnownsOnly)
194            .Case("KnownsAndLocals", AK_KnownsAndLocals)
195            .Case("All", AK_All)
196            .Default(AK_Invalid);
197
198    if (Aggressiveness == AK_Invalid)
199      Mgr.reportInvalidCheckerOptionValue(this, "WarnOn",
200          "either \"KnownsOnly\", \"KnownsAndLocals\" or \"All\" string value");
201  };
202
203private:
204  BugType BT{this, "Use-after-move", categories::CXXMoveSemantics};
205
206  // Check if the given form of potential misuse of a given object
207  // should be reported. If so, get it reported. The callback from which
208  // this function was called should immediately return after the call
209  // because this function adds one or two transitions.
210  void modelUse(ProgramStateRef State, const MemRegion *Region,
211                const CXXRecordDecl *RD, MisuseKind MK,
212                CheckerContext &C) const;
213
214  // Returns the exploded node against which the report was emitted.
215  // The caller *must* add any further transitions against this node.
216  // Returns nullptr and does not report if such node already exists.
217  ExplodedNode *tryToReportBug(const MemRegion *Region, const CXXRecordDecl *RD,
218                               CheckerContext &C, MisuseKind MK) const;
219
220  bool isInMoveSafeContext(const LocationContext *LC) const;
221  bool isStateResetMethod(const CXXMethodDecl *MethodDec) const;
222  bool isMoveSafeMethod(const CXXMethodDecl *MethodDec) const;
223  const ExplodedNode *getMoveLocation(const ExplodedNode *N,
224                                      const MemRegion *Region,
225                                      CheckerContext &C) const;
226};
227} // end anonymous namespace
228
229REGISTER_MAP_WITH_PROGRAMSTATE(TrackedRegionMap, const MemRegion *, RegionState)
230
231// Define the inter-checker API.
232namespace clang {
233namespace ento {
234namespace move {
235bool isMovedFrom(ProgramStateRef State, const MemRegion *Region) {
236  const RegionState *RS = State->get<TrackedRegionMap>(Region);
237  return RS && (RS->isMoved() || RS->isReported());
238}
239} // namespace move
240} // namespace ento
241} // namespace clang
242
243// If a region is removed all of the subregions needs to be removed too.
244static ProgramStateRef removeFromState(ProgramStateRef State,
245                                       const MemRegion *Region) {
246  if (!Region)
247    return State;
248  for (auto &E : State->get<TrackedRegionMap>()) {
249    if (E.first->isSubRegionOf(Region))
250      State = State->remove<TrackedRegionMap>(E.first);
251  }
252  return State;
253}
254
255static bool isAnyBaseRegionReported(ProgramStateRef State,
256                                    const MemRegion *Region) {
257  for (auto &E : State->get<TrackedRegionMap>()) {
258    if (Region->isSubRegionOf(E.first) && E.second.isReported())
259      return true;
260  }
261  return false;
262}
263
264static const MemRegion *unwrapRValueReferenceIndirection(const MemRegion *MR) {
265  if (const auto *SR = dyn_cast_or_null<SymbolicRegion>(MR)) {
266    SymbolRef Sym = SR->getSymbol();
267    if (Sym->getType()->isRValueReferenceType())
268      if (const MemRegion *OriginMR = Sym->getOriginRegion())
269        return OriginMR;
270  }
271  return MR;
272}
273
274PathDiagnosticPieceRef
275MoveChecker::MovedBugVisitor::VisitNode(const ExplodedNode *N,
276                                        BugReporterContext &BRC,
277                                        PathSensitiveBugReport &BR) {
278  // We need only the last move of the reported object's region.
279  // The visitor walks the ExplodedGraph backwards.
280  if (Found)
281    return nullptr;
282  ProgramStateRef State = N->getState();
283  ProgramStateRef StatePrev = N->getFirstPred()->getState();
284  const RegionState *TrackedObject = State->get<TrackedRegionMap>(Region);
285  const RegionState *TrackedObjectPrev =
286      StatePrev->get<TrackedRegionMap>(Region);
287  if (!TrackedObject)
288    return nullptr;
289  if (TrackedObjectPrev && TrackedObject)
290    return nullptr;
291
292  // Retrieve the associated statement.
293  const Stmt *S = N->getStmtForDiagnostics();
294  if (!S)
295    return nullptr;
296  Found = true;
297
298  SmallString<128> Str;
299  llvm::raw_svector_ostream OS(Str);
300
301  ObjectKind OK = Chk.classifyObject(Region, RD);
302  switch (OK.StdKind) {
303    case SK_SmartPtr:
304      if (MK == MK_Dereference) {
305        OS << "Smart pointer";
306        Chk.explainObject(OS, Region, RD, MK);
307        OS << " is reset to null when moved from";
308        break;
309      }
310
311      // If it's not a dereference, we don't care if it was reset to null
312      // or that it is even a smart pointer.
313      [[fallthrough]];
314    case SK_NonStd:
315    case SK_Safe:
316      OS << "Object";
317      Chk.explainObject(OS, Region, RD, MK);
318      OS << " is moved";
319      break;
320    case SK_Unsafe:
321      OS << "Object";
322      Chk.explainObject(OS, Region, RD, MK);
323      OS << " is left in a valid but unspecified state after move";
324      break;
325  }
326
327  // Generate the extra diagnostic.
328  PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
329                             N->getLocationContext());
330  return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true);
331}
332
333const ExplodedNode *MoveChecker::getMoveLocation(const ExplodedNode *N,
334                                                 const MemRegion *Region,
335                                                 CheckerContext &C) const {
336  // Walk the ExplodedGraph backwards and find the first node that referred to
337  // the tracked region.
338  const ExplodedNode *MoveNode = N;
339
340  while (N) {
341    ProgramStateRef State = N->getState();
342    if (!State->get<TrackedRegionMap>(Region))
343      break;
344    MoveNode = N;
345    N = N->pred_empty() ? nullptr : *(N->pred_begin());
346  }
347  return MoveNode;
348}
349
350void MoveChecker::modelUse(ProgramStateRef State, const MemRegion *Region,
351                           const CXXRecordDecl *RD, MisuseKind MK,
352                           CheckerContext &C) const {
353  assert(!C.isDifferent() && "No transitions should have been made by now");
354  const RegionState *RS = State->get<TrackedRegionMap>(Region);
355  ObjectKind OK = classifyObject(Region, RD);
356
357  // Just in case: if it's not a smart pointer but it does have operator *,
358  // we shouldn't call the bug a dereference.
359  if (MK == MK_Dereference && OK.StdKind != SK_SmartPtr)
360    MK = MK_FunCall;
361
362  if (!RS || !shouldWarnAbout(OK, MK)
363          || isInMoveSafeContext(C.getLocationContext())) {
364    // Finalize changes made by the caller.
365    C.addTransition(State);
366    return;
367  }
368
369  // Don't report it in case if any base region is already reported.
370  // But still generate a sink in case of UB.
371  // And still finalize changes made by the caller.
372  if (isAnyBaseRegionReported(State, Region)) {
373    if (misuseCausesCrash(MK)) {
374      C.generateSink(State, C.getPredecessor());
375    } else {
376      C.addTransition(State);
377    }
378    return;
379  }
380
381  ExplodedNode *N = tryToReportBug(Region, RD, C, MK);
382
383  // If the program has already crashed on this path, don't bother.
384  if (!N || N->isSink())
385    return;
386
387  State = State->set<TrackedRegionMap>(Region, RegionState::getReported());
388  C.addTransition(State, N);
389}
390
391ExplodedNode *MoveChecker::tryToReportBug(const MemRegion *Region,
392                                          const CXXRecordDecl *RD,
393                                          CheckerContext &C,
394                                          MisuseKind MK) const {
395  if (ExplodedNode *N = misuseCausesCrash(MK) ? C.generateErrorNode()
396                                              : C.generateNonFatalErrorNode()) {
397    // Uniqueing report to the same object.
398    PathDiagnosticLocation LocUsedForUniqueing;
399    const ExplodedNode *MoveNode = getMoveLocation(N, Region, C);
400
401    if (const Stmt *MoveStmt = MoveNode->getStmtForDiagnostics())
402      LocUsedForUniqueing = PathDiagnosticLocation::createBegin(
403          MoveStmt, C.getSourceManager(), MoveNode->getLocationContext());
404
405    // Creating the error message.
406    llvm::SmallString<128> Str;
407    llvm::raw_svector_ostream OS(Str);
408    switch(MK) {
409      case MK_FunCall:
410        OS << "Method called on moved-from object";
411        explainObject(OS, Region, RD, MK);
412        break;
413      case MK_Copy:
414        OS << "Moved-from object";
415        explainObject(OS, Region, RD, MK);
416        OS << " is copied";
417        break;
418      case MK_Move:
419        OS << "Moved-from object";
420        explainObject(OS, Region, RD, MK);
421        OS << " is moved";
422        break;
423      case MK_Dereference:
424        OS << "Dereference of null smart pointer";
425        explainObject(OS, Region, RD, MK);
426        break;
427    }
428
429    auto R = std::make_unique<PathSensitiveBugReport>(
430        BT, OS.str(), N, LocUsedForUniqueing,
431        MoveNode->getLocationContext()->getDecl());
432    R->addVisitor(std::make_unique<MovedBugVisitor>(*this, Region, RD, MK));
433    C.emitReport(std::move(R));
434    return N;
435  }
436  return nullptr;
437}
438
439void MoveChecker::checkPostCall(const CallEvent &Call,
440                                CheckerContext &C) const {
441  const auto *AFC = dyn_cast<AnyFunctionCall>(&Call);
442  if (!AFC)
443    return;
444
445  ProgramStateRef State = C.getState();
446  const auto MethodDecl = dyn_cast_or_null<CXXMethodDecl>(AFC->getDecl());
447  if (!MethodDecl)
448    return;
449
450  // Check if an object became moved-from.
451  // Object can become moved from after a call to move assignment operator or
452  // move constructor .
453  const auto *ConstructorDecl = dyn_cast<CXXConstructorDecl>(MethodDecl);
454  if (ConstructorDecl && !ConstructorDecl->isMoveConstructor())
455    return;
456
457  if (!ConstructorDecl && !MethodDecl->isMoveAssignmentOperator())
458    return;
459
460  const auto ArgRegion = AFC->getArgSVal(0).getAsRegion();
461  if (!ArgRegion)
462    return;
463
464  // Skip moving the object to itself.
465  const auto *CC = dyn_cast_or_null<CXXConstructorCall>(&Call);
466  if (CC && CC->getCXXThisVal().getAsRegion() == ArgRegion)
467    return;
468
469  if (const auto *IC = dyn_cast<CXXInstanceCall>(AFC))
470    if (IC->getCXXThisVal().getAsRegion() == ArgRegion)
471      return;
472
473  const MemRegion *BaseRegion = ArgRegion->getBaseRegion();
474  // Skip temp objects because of their short lifetime.
475  if (BaseRegion->getAs<CXXTempObjectRegion>() ||
476      AFC->getArgExpr(0)->isPRValue())
477    return;
478  // If it has already been reported do not need to modify the state.
479
480  if (State->get<TrackedRegionMap>(ArgRegion))
481    return;
482
483  const CXXRecordDecl *RD = MethodDecl->getParent();
484  ObjectKind OK = classifyObject(ArgRegion, RD);
485  if (shouldBeTracked(OK)) {
486    // Mark object as moved-from.
487    State = State->set<TrackedRegionMap>(ArgRegion, RegionState::getMoved());
488    C.addTransition(State);
489    return;
490  }
491  assert(!C.isDifferent() && "Should not have made transitions on this path!");
492}
493
494bool MoveChecker::isMoveSafeMethod(const CXXMethodDecl *MethodDec) const {
495  // We abandon the cases where bool/void/void* conversion happens.
496  if (const auto *ConversionDec =
497          dyn_cast_or_null<CXXConversionDecl>(MethodDec)) {
498    const Type *Tp = ConversionDec->getConversionType().getTypePtrOrNull();
499    if (!Tp)
500      return false;
501    if (Tp->isBooleanType() || Tp->isVoidType() || Tp->isVoidPointerType())
502      return true;
503  }
504  // Function call `empty` can be skipped.
505  return (MethodDec && MethodDec->getDeclName().isIdentifier() &&
506      (MethodDec->getName().lower() == "empty" ||
507       MethodDec->getName().lower() == "isempty"));
508}
509
510bool MoveChecker::isStateResetMethod(const CXXMethodDecl *MethodDec) const {
511  if (!MethodDec)
512      return false;
513  if (MethodDec->hasAttr<ReinitializesAttr>())
514      return true;
515  if (MethodDec->getDeclName().isIdentifier()) {
516    std::string MethodName = MethodDec->getName().lower();
517    // TODO: Some of these methods (eg., resize) are not always resetting
518    // the state, so we should consider looking at the arguments.
519    if (MethodName == "assign" || MethodName == "clear" ||
520        MethodName == "destroy" || MethodName == "reset" ||
521        MethodName == "resize" || MethodName == "shrink")
522      return true;
523  }
524  return false;
525}
526
527// Don't report an error inside a move related operation.
528// We assume that the programmer knows what she does.
529bool MoveChecker::isInMoveSafeContext(const LocationContext *LC) const {
530  do {
531    const auto *CtxDec = LC->getDecl();
532    auto *CtorDec = dyn_cast_or_null<CXXConstructorDecl>(CtxDec);
533    auto *DtorDec = dyn_cast_or_null<CXXDestructorDecl>(CtxDec);
534    auto *MethodDec = dyn_cast_or_null<CXXMethodDecl>(CtxDec);
535    if (DtorDec || (CtorDec && CtorDec->isCopyOrMoveConstructor()) ||
536        (MethodDec && MethodDec->isOverloadedOperator() &&
537         MethodDec->getOverloadedOperator() == OO_Equal) ||
538        isStateResetMethod(MethodDec) || isMoveSafeMethod(MethodDec))
539      return true;
540  } while ((LC = LC->getParent()));
541  return false;
542}
543
544bool MoveChecker::belongsTo(const CXXRecordDecl *RD,
545                            const llvm::StringSet<> &Set) const {
546  const IdentifierInfo *II = RD->getIdentifier();
547  return II && Set.count(II->getName());
548}
549
550MoveChecker::ObjectKind
551MoveChecker::classifyObject(const MemRegion *MR,
552                            const CXXRecordDecl *RD) const {
553  // Local variables and local rvalue references are classified as "Local".
554  // For the purposes of this checker, we classify move-safe STL types
555  // as not-"STL" types, because that's how the checker treats them.
556  MR = unwrapRValueReferenceIndirection(MR);
557  bool IsLocal =
558      isa_and_nonnull<VarRegion, CXXLifetimeExtendedObjectRegion>(MR) &&
559      isa<StackSpaceRegion>(MR->getMemorySpace());
560
561  if (!RD || !RD->getDeclContext()->isStdNamespace())
562    return { IsLocal, SK_NonStd };
563
564  if (belongsTo(RD, StdSmartPtrClasses))
565    return { IsLocal, SK_SmartPtr };
566
567  if (belongsTo(RD, StdSafeClasses))
568    return { IsLocal, SK_Safe };
569
570  return { IsLocal, SK_Unsafe };
571}
572
573void MoveChecker::explainObject(llvm::raw_ostream &OS, const MemRegion *MR,
574                                const CXXRecordDecl *RD, MisuseKind MK) const {
575  // We may need a leading space every time we actually explain anything,
576  // and we never know if we are to explain anything until we try.
577  if (const auto DR =
578          dyn_cast_or_null<DeclRegion>(unwrapRValueReferenceIndirection(MR))) {
579    const auto *RegionDecl = cast<NamedDecl>(DR->getDecl());
580    OS << " '" << RegionDecl->getDeclName() << "'";
581  }
582
583  ObjectKind OK = classifyObject(MR, RD);
584  switch (OK.StdKind) {
585    case SK_NonStd:
586    case SK_Safe:
587      break;
588    case SK_SmartPtr:
589      if (MK != MK_Dereference)
590        break;
591
592      // We only care about the type if it's a dereference.
593      [[fallthrough]];
594    case SK_Unsafe:
595      OS << " of type '" << RD->getQualifiedNameAsString() << "'";
596      break;
597  };
598}
599
600void MoveChecker::checkPreCall(const CallEvent &Call, CheckerContext &C) const {
601  ProgramStateRef State = C.getState();
602
603  // Remove the MemRegions from the map on which a ctor/dtor call or assignment
604  // happened.
605
606  // Checking constructor calls.
607  if (const auto *CC = dyn_cast<CXXConstructorCall>(&Call)) {
608    State = removeFromState(State, CC->getCXXThisVal().getAsRegion());
609    auto CtorDec = CC->getDecl();
610    // Check for copying a moved-from object and report the bug.
611    if (CtorDec && CtorDec->isCopyOrMoveConstructor()) {
612      const MemRegion *ArgRegion = CC->getArgSVal(0).getAsRegion();
613      const CXXRecordDecl *RD = CtorDec->getParent();
614      MisuseKind MK = CtorDec->isMoveConstructor() ? MK_Move : MK_Copy;
615      modelUse(State, ArgRegion, RD, MK, C);
616      return;
617    }
618  }
619
620  const auto IC = dyn_cast<CXXInstanceCall>(&Call);
621  if (!IC)
622    return;
623
624  const MemRegion *ThisRegion = IC->getCXXThisVal().getAsRegion();
625  if (!ThisRegion)
626    return;
627
628  // The remaining part is check only for method call on a moved-from object.
629  const auto MethodDecl = dyn_cast_or_null<CXXMethodDecl>(IC->getDecl());
630  if (!MethodDecl)
631    return;
632
633  // Calling a destructor on a moved object is fine.
634  if (isa<CXXDestructorDecl>(MethodDecl))
635    return;
636
637  // We want to investigate the whole object, not only sub-object of a parent
638  // class in which the encountered method defined.
639  ThisRegion = ThisRegion->getMostDerivedObjectRegion();
640
641  if (isStateResetMethod(MethodDecl)) {
642    State = removeFromState(State, ThisRegion);
643    C.addTransition(State);
644    return;
645  }
646
647  if (isMoveSafeMethod(MethodDecl))
648    return;
649
650  // Store class declaration as well, for bug reporting purposes.
651  const CXXRecordDecl *RD = MethodDecl->getParent();
652
653  if (MethodDecl->isOverloadedOperator()) {
654    OverloadedOperatorKind OOK = MethodDecl->getOverloadedOperator();
655
656    if (OOK == OO_Equal) {
657      // Remove the tracked object for every assignment operator, but report bug
658      // only for move or copy assignment's argument.
659      State = removeFromState(State, ThisRegion);
660
661      if (MethodDecl->isCopyAssignmentOperator() ||
662          MethodDecl->isMoveAssignmentOperator()) {
663        const MemRegion *ArgRegion = IC->getArgSVal(0).getAsRegion();
664        MisuseKind MK =
665            MethodDecl->isMoveAssignmentOperator() ? MK_Move : MK_Copy;
666        modelUse(State, ArgRegion, RD, MK, C);
667        return;
668      }
669      C.addTransition(State);
670      return;
671    }
672
673    if (OOK == OO_Star || OOK == OO_Arrow) {
674      modelUse(State, ThisRegion, RD, MK_Dereference, C);
675      return;
676    }
677  }
678
679  modelUse(State, ThisRegion, RD, MK_FunCall, C);
680}
681
682void MoveChecker::checkDeadSymbols(SymbolReaper &SymReaper,
683                                   CheckerContext &C) const {
684  ProgramStateRef State = C.getState();
685  TrackedRegionMapTy TrackedRegions = State->get<TrackedRegionMap>();
686  for (auto E : TrackedRegions) {
687    const MemRegion *Region = E.first;
688    bool IsRegDead = !SymReaper.isLiveRegion(Region);
689
690    // Remove the dead regions from the region map.
691    if (IsRegDead) {
692      State = State->remove<TrackedRegionMap>(Region);
693    }
694  }
695  C.addTransition(State);
696}
697
698ProgramStateRef MoveChecker::checkRegionChanges(
699    ProgramStateRef State, const InvalidatedSymbols *Invalidated,
700    ArrayRef<const MemRegion *> RequestedRegions,
701    ArrayRef<const MemRegion *> InvalidatedRegions,
702    const LocationContext *LCtx, const CallEvent *Call) const {
703  if (Call) {
704    // Relax invalidation upon function calls: only invalidate parameters
705    // that are passed directly via non-const pointers or non-const references
706    // or rvalue references.
707    // In case of an InstanceCall don't invalidate the this-region since
708    // it is fully handled in checkPreCall and checkPostCall.
709    const MemRegion *ThisRegion = nullptr;
710    if (const auto *IC = dyn_cast<CXXInstanceCall>(Call))
711      ThisRegion = IC->getCXXThisVal().getAsRegion();
712
713    // Requested ("explicit") regions are the regions passed into the call
714    // directly, but not all of them end up being invalidated.
715    // But when they do, they appear in the InvalidatedRegions array as well.
716    for (const auto *Region : RequestedRegions) {
717      if (ThisRegion != Region &&
718          llvm::is_contained(InvalidatedRegions, Region))
719        State = removeFromState(State, Region);
720    }
721  } else {
722    // For invalidations that aren't caused by calls, assume nothing. In
723    // particular, direct write into an object's field invalidates the status.
724    for (const auto *Region : InvalidatedRegions)
725      State = removeFromState(State, Region->getBaseRegion());
726  }
727
728  return State;
729}
730
731void MoveChecker::printState(raw_ostream &Out, ProgramStateRef State,
732                             const char *NL, const char *Sep) const {
733
734  TrackedRegionMapTy RS = State->get<TrackedRegionMap>();
735
736  if (!RS.isEmpty()) {
737    Out << Sep << "Moved-from objects :" << NL;
738    for (auto I: RS) {
739      I.first->dumpToStream(Out);
740      if (I.second.isMoved())
741        Out << ": moved";
742      else
743        Out << ": moved and reported";
744      Out << NL;
745    }
746  }
747}
748void ento::registerMoveChecker(CheckerManager &mgr) {
749  MoveChecker *chk = mgr.registerChecker<MoveChecker>();
750  chk->setAggressiveness(
751      mgr.getAnalyzerOptions().getCheckerStringOption(chk, "WarnOn"), mgr);
752}
753
754bool ento::shouldRegisterMoveChecker(const CheckerManager &mgr) {
755  return true;
756}
757