// SmartPtrModeling.cpp - Model behavior of C++ smart pointers - C++ ------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file defines a checker that models various aspects of

// C++ smart pointer behavior.

//

//===----------------------------------------------------------------------===//

#include "Move.h"

#include "SmartPtr.h"

#include "clang/AST/DeclCXX.h"

#include "clang/AST/DeclarationName.h"

#include "clang/AST/ExprCXX.h"

#include "clang/AST/Type.h"

#include "clang/Basic/LLVM.h"

#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"

#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"

#include "clang/StaticAnalyzer/Core/Checker.h"

#include "clang/StaticAnalyzer/Core/CheckerManager.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"

#include <string>

using namespace clang;

using namespace ento;

namespace {

class SmartPtrModeling

    : public Checker<eval::Call, check::DeadSymbols, check::RegionChanges,

                     check::LiveSymbols> {

  bool isBoolConversionMethod(const CallEvent &Call) const;

public:

  // Whether the checker should model for null dereferences of smart pointers.

  DefaultBool ModelSmartPtrDereference;

  bool evalCall(const CallEvent &Call, CheckerContext &C) const;

  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;

  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;

  ProgramStateRef

  checkRegionChanges(ProgramStateRef State,

                     const InvalidatedSymbols *Invalidated,

                     ArrayRef<const MemRegion *> ExplicitRegions,

                     ArrayRef<const MemRegion *> Regions,

                     const LocationContext *LCtx, const CallEvent *Call) const;

  void printState(raw_ostream &Out, ProgramStateRef State, const char *NL,

                  const char *Sep) const override;

  void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const;

private:

  void handleReset(const CallEvent &Call, CheckerContext &C) const;

  void handleRelease(const CallEvent &Call, CheckerContext &C) const;

  void handleSwap(const CallEvent &Call, CheckerContext &C) const;

  void handleGet(const CallEvent &Call, CheckerContext &C) const;

  bool handleAssignOp(const CallEvent &Call, CheckerContext &C) const;

  bool handleMoveCtr(const CallEvent &Call, CheckerContext &C,

                     const MemRegion *ThisRegion) const;

  bool updateMovedSmartPointers(CheckerContext &C, const MemRegion *ThisRegion,

                                const MemRegion *OtherSmartPtrRegion) const;

  void handleBoolConversion(const CallEvent &Call, CheckerContext &C) const;

  using SmartPtrMethodHandlerFn =

      void (SmartPtrModeling::*)(const CallEvent &Call, CheckerContext &) const;

  CallDescriptionMap<SmartPtrMethodHandlerFn> SmartPtrMethodHandlers{

      {{"reset"}, &SmartPtrModeling::handleReset},

      {{"release"}, &SmartPtrModeling::handleRelease},

      {{"swap", 1}, &SmartPtrModeling::handleSwap},

      {{"get"}, &SmartPtrModeling::handleGet}};

};

} // end of anonymous namespace

REGISTER_MAP_WITH_PROGRAMSTATE(TrackedRegionMap, const MemRegion *, SVal)

// Define the inter-checker API.

namespace clang {

namespace ento {

namespace smartptr {

bool isStdSmartPtrCall(const CallEvent &Call) {

  const auto *MethodDecl = dyn_cast_or_null<CXXMethodDecl>(Call.getDecl());

  if (!MethodDecl || 
!MethodDecl->getParent()15.0k
)

    return false;

  const auto *RecordDecl = MethodDecl->getParent();

  if (!RecordDecl || !RecordDecl->getDeclContext()->isStdNamespace())

    return false;

  if (RecordDecl->getDeclName().isIdentifier()) {

    StringRef Name = RecordDecl->getName();

    return Name == "shared_ptr" || Name == "unique_ptr" || 
Name == "weak_ptr"3.21k
;

  }

  return false;

}

bool isNullSmartPtr(const ProgramStateRef State, const MemRegion *ThisRegion) {

  const auto *InnerPointVal = State->get<TrackedRegionMap>(ThisRegion);

  return InnerPointVal &&

         !State->assume(InnerPointVal->castAs<DefinedOrUnknownSVal>(), true);

}

} // namespace smartptr

} // namespace ento

} // namespace clang

// If a region is removed all of the subregions need to be removed too.

static TrackedRegionMapTy

removeTrackedSubregions(TrackedRegionMapTy RegionMap,

                        TrackedRegionMapTy::Factory &RegionMapFactory,

                        const MemRegion *Region) {

  if (!Region)

    return RegionMap;

  for (const auto &E : RegionMap) {

    if (E.first->isSubRegionOf(Region))

      RegionMap = RegionMapFactory.remove(RegionMap, E.first);

  }

  return RegionMap;

}

static ProgramStateRef updateSwappedRegion(ProgramStateRef State,

                                           const MemRegion *Region,

                                           const SVal *RegionInnerPointerVal) {

  if (RegionInnerPointerVal) {

    State = State->set<TrackedRegionMap>(Region, *RegionInnerPointerVal);

  } else {

    State = State->remove<TrackedRegionMap>(Region);

  }

  return State;

}

// Helper method to get the inner pointer type of specialized smart pointer

// Returns empty type if not found valid inner pointer type.

static QualType getInnerPointerType(const CallEvent &Call, CheckerContext &C) {

  const auto *MethodDecl = dyn_cast_or_null<CXXMethodDecl>(Call.getDecl());

  if (!MethodDecl || !MethodDecl->getParent())

    return {};

  const auto *RecordDecl = MethodDecl->getParent();

  if (!RecordDecl || !RecordDecl->isInStdNamespace())

    return {};

  const auto *TSD = dyn_cast<ClassTemplateSpecializationDecl>(RecordDecl);

  if (!TSD)

    return {};

  auto TemplateArgs = TSD->getTemplateArgs().asArray();

  if (TemplateArgs.size() == 0)

    return {};

  auto InnerValueType = TemplateArgs[0].getAsType();

  return C.getASTContext().getPointerType(InnerValueType.getCanonicalType());

}

// Helper method to pretty print region and avoid extra spacing.

static void checkAndPrettyPrintRegion(llvm::raw_ostream &OS,

                                      const MemRegion *Region) {

  if (Region->canPrintPretty()) {

    OS << " ";

    Region->printPretty(OS);

  }

}

bool SmartPtrModeling::isBoolConversionMethod(const CallEvent &Call) const {

  // TODO: Update CallDescription to support anonymous calls?

  // TODO: Handle other methods, such as .get() or .release().

  // But once we do, we'd need a visitor to explain null dereferences

  // that are found via such modeling.

  const auto *CD = dyn_cast_or_null<CXXConversionDecl>(Call.getDecl());

  return CD && 
CD->getConversionType()->isBooleanType()30
;

}

bool SmartPtrModeling::evalCall(const CallEvent &Call,

                                CheckerContext &C) const {

  ProgramStateRef State = C.getState();

  if (!smartptr::isStdSmartPtrCall(Call))

    return false;

  if (isBoolConversionMethod(Call)) {

    const MemRegion *ThisR =

        cast<CXXInstanceCall>(&Call)->getCXXThisVal().getAsRegion();

    if (ModelSmartPtrDereference) {

      // The check for the region is moved is duplicated in handleBoolOperation

      // method.

      // FIXME: Once we model std::move for smart pointers clean up this and use

      // that modeling.

      handleBoolConversion(Call, C);

      return true;

    } else {

      if (!move::isMovedFrom(State, ThisR)) {

        // TODO: Model this case as well. At least, avoid invalidation of

        // globals.

        return false;

      }

      // TODO: Add a note to bug reports describing this decision.

      C.addTransition(State->BindExpr(

          Call.getOriginExpr(), C.getLocationContext(),

          C.getSValBuilder().makeZeroVal(Call.getResultType())));

      return true;

    }

  }

  if (!ModelSmartPtrDereference)

    return false;

  if (const auto *CC = dyn_cast<CXXConstructorCall>(&Call)) {

    if (CC->getDecl()->isCopyConstructor())

      return false;

    const MemRegion *ThisRegion = CC->getCXXThisVal().getAsRegion();

    if (!ThisRegion)

      return false;

    if (CC->getDecl()->isMoveConstructor())

      return handleMoveCtr(Call, C, ThisRegion);

    if (Call.getNumArgs() == 0) {

      auto NullVal = C.getSValBuilder().makeNull();

      State = State->set<TrackedRegionMap>(ThisRegion, NullVal);

      C.addTransition(

          State, C.getNoteTag([ThisRegion](PathSensitiveBugReport &BR,

                                           llvm::raw_ostream &OS) {

            if (&BR.getBugType() != smartptr::getNullDereferenceBugType() ||

                !BR.isInteresting(ThisRegion))

              return;

            OS << "Default constructed smart pointer";

            checkAndPrettyPrintRegion(OS, ThisRegion);

            OS << " is null";

          }));

    } else {

      const auto *TrackingExpr = Call.getArgExpr(0);

      assert(TrackingExpr->getType()->isPointerType() &&

             "Adding a non pointer value to TrackedRegionMap");

      auto ArgVal = Call.getArgSVal(0);

      State = State->set<TrackedRegionMap>(ThisRegion, ArgVal);

      C.addTransition(State, C.getNoteTag([ThisRegion, TrackingExpr,

                                           ArgVal](PathSensitiveBugReport &BR,

                                                   llvm::raw_ostream &OS) {

        if (&BR.getBugType() != smartptr::getNullDereferenceBugType() ||

            !BR.isInteresting(ThisRegion))

          return;

        bugreporter::trackExpressionValue(BR.getErrorNode(), TrackingExpr, BR);

        OS << "Smart pointer";

        checkAndPrettyPrintRegion(OS, ThisRegion);

        if (ArgVal.isZeroConstant())

          OS << " is constructed using a null value";

        else

          OS << " is constructed";

      }));

    }

    return true;

  }

  if (handleAssignOp(Call, C))

    return true;

  const SmartPtrMethodHandlerFn *Handler = SmartPtrMethodHandlers.lookup(Call);

  if (!Handler)

    return false;

  (this->**Handler)(Call, C);

  return C.isDifferent();

}

void SmartPtrModeling::checkDeadSymbols(SymbolReaper &SymReaper,

                                        CheckerContext &C) const {

  ProgramStateRef State = C.getState();

  // Clean up dead regions from the region map.

  TrackedRegionMapTy TrackedRegions = State->get<TrackedRegionMap>();

  for (auto E : TrackedRegions) {

    const MemRegion *Region = E.first;

    bool IsRegDead = !SymReaper.isLiveRegion(Region);

    if (IsRegDead)

      State = State->remove<TrackedRegionMap>(Region);

  }

  C.addTransition(State);

}

void SmartPtrModeling::printState(raw_ostream &Out, ProgramStateRef State,

                                  const char *NL, const char *Sep) const {

  TrackedRegionMapTy RS = State->get<TrackedRegionMap>();

  if (!RS.isEmpty()) {

    Out << Sep << "Smart ptr regions :" << NL;

    for (auto I : RS) {

      I.first->dumpToStream(Out);

      if (smartptr::isNullSmartPtr(State, I.first))

        Out << ": Null";

      else

        Out << ": Non Null";

      Out << NL;

    }

  }

}

ProgramStateRef SmartPtrModeling::checkRegionChanges(

    ProgramStateRef State, const InvalidatedSymbols *Invalidated,

    ArrayRef<const MemRegion *> ExplicitRegions,

    ArrayRef<const MemRegion *> Regions, const LocationContext *LCtx,

    const CallEvent *Call) const {

  TrackedRegionMapTy RegionMap = State->get<TrackedRegionMap>();

  TrackedRegionMapTy::Factory &RegionMapFactory =

      State->get_context<TrackedRegionMap>();

  for (const auto *Region : Regions)

    RegionMap = removeTrackedSubregions(RegionMap, RegionMapFactory,

                                        Region->getBaseRegion());

  return State->set<TrackedRegionMap>(RegionMap);

}

void SmartPtrModeling::checkLiveSymbols(ProgramStateRef State,

                                        SymbolReaper &SR) const {

  // Marking tracked symbols alive

  TrackedRegionMapTy TrackedRegions = State->get<TrackedRegionMap>();

  for (auto I = TrackedRegions.begin(), E = TrackedRegions.end(); I != E; 
++I654
) {

    SVal Val = I->second;

    for (auto si = Val.symbol_begin(), se = Val.symbol_end(); si != se; 
++si257
) {

      SR.markLive(*si);

    }

  }

}

void SmartPtrModeling::handleReset(const CallEvent &Call,

                                   CheckerContext &C) const {

  ProgramStateRef State = C.getState();

  const auto *IC = dyn_cast<CXXInstanceCall>(&Call);

  if (!IC)

    return;

  const MemRegion *ThisRegion = IC->getCXXThisVal().getAsRegion();

  if (!ThisRegion)

    return;

  assert(Call.getArgExpr(0)->getType()->isPointerType() &&

         "Adding a non pointer value to TrackedRegionMap");

  State = State->set<TrackedRegionMap>(ThisRegion, Call.getArgSVal(0));

  const auto *TrackingExpr = Call.getArgExpr(0);

  C.addTransition(

      State, C.getNoteTag([ThisRegion, TrackingExpr](PathSensitiveBugReport &BR,

                                                     llvm::raw_ostream &OS) {

        if (&BR.getBugType() != smartptr::getNullDereferenceBugType() ||

            !BR.isInteresting(ThisRegion))

          return;

        bugreporter::trackExpressionValue(BR.getErrorNode(), TrackingExpr, BR);

        OS << "Smart pointer";

        checkAndPrettyPrintRegion(OS, ThisRegion);

        OS << " reset using a null value";

      }));

  // TODO: Make sure to ivalidate the region in the Store if we don't have

  // time to model all methods.

}

void SmartPtrModeling::handleRelease(const CallEvent &Call,

                                     CheckerContext &C) const {

  ProgramStateRef State = C.getState();

  const auto *IC = dyn_cast<CXXInstanceCall>(&Call);

  if (!IC)

    return;

  const MemRegion *ThisRegion = IC->getCXXThisVal().getAsRegion();

  if (!ThisRegion)

    return;

  const auto *InnerPointVal = State->get<TrackedRegionMap>(ThisRegion);

  if (InnerPointVal) {

    State = State->BindExpr(Call.getOriginExpr(), C.getLocationContext(),

                            *InnerPointVal);

  }

  auto ValueToUpdate = C.getSValBuilder().makeNull();

  State = State->set<TrackedRegionMap>(ThisRegion, ValueToUpdate);

  C.addTransition(State, C.getNoteTag([ThisRegion](PathSensitiveBugReport &BR,

                                                   llvm::raw_ostream &OS) {

    if (&BR.getBugType() != smartptr::getNullDereferenceBugType() ||

        !BR.isInteresting(ThisRegion))

      return;

    OS << "Smart pointer";

    checkAndPrettyPrintRegion(OS, ThisRegion);

    OS << " is released and set to null";

  }));

  // TODO: Add support to enable MallocChecker to start tracking the raw

  // pointer.

}

void SmartPtrModeling::handleSwap(const CallEvent &Call,

                                  CheckerContext &C) const {

  // To model unique_ptr::swap() method.

  const auto *IC = dyn_cast<CXXInstanceCall>(&Call);

  if (!IC)

    return;

  const MemRegion *ThisRegion = IC->getCXXThisVal().getAsRegion();

  if (!ThisRegion)

    return;

  const auto *ArgRegion = Call.getArgSVal(0).getAsRegion();

  if (!ArgRegion)

    return;

  auto State = C.getState();

  const auto *ThisRegionInnerPointerVal =

      State->get<TrackedRegionMap>(ThisRegion);

  const auto *ArgRegionInnerPointerVal =

      State->get<TrackedRegionMap>(ArgRegion);

  // Swap the tracked region values.

  State = updateSwappedRegion(State, ThisRegion, ArgRegionInnerPointerVal);

  State = updateSwappedRegion(State, ArgRegion, ThisRegionInnerPointerVal);

  C.addTransition(

      State, C.getNoteTag([ThisRegion, ArgRegion](PathSensitiveBugReport &BR,

                                                  llvm::raw_ostream &OS) {

        if (&BR.getBugType() != smartptr::getNullDereferenceBugType() ||

            !BR.isInteresting(ThisRegion))

          return;

        BR.markInteresting(ArgRegion);

        OS << "Swapped null smart pointer";

        checkAndPrettyPrintRegion(OS, ArgRegion);

        OS << " with smart pointer";

        checkAndPrettyPrintRegion(OS, ThisRegion);

      }));

}

void SmartPtrModeling::handleGet(const CallEvent &Call,

                                 CheckerContext &C) const {

  ProgramStateRef State = C.getState();

  const auto *IC = dyn_cast<CXXInstanceCall>(&Call);

  if (!IC)

    return;

  const MemRegion *ThisRegion = IC->getCXXThisVal().getAsRegion();

  if (!ThisRegion)

    return;

  SVal InnerPointerVal;

  if (const auto *InnerValPtr = State->get<TrackedRegionMap>(ThisRegion)) {

    InnerPointerVal = *InnerValPtr;

  } else {

    const auto *CallExpr = Call.getOriginExpr();

    InnerPointerVal = C.getSValBuilder().conjureSymbolVal(

        CallExpr, C.getLocationContext(), Call.getResultType(), C.blockCount());

    State = State->set<TrackedRegionMap>(ThisRegion, InnerPointerVal);

  }

  State = State->BindExpr(Call.getOriginExpr(), C.getLocationContext(),

                          InnerPointerVal);

  // TODO: Add NoteTag, for how the raw pointer got using 'get' method.

  C.addTransition(State);

}

bool SmartPtrModeling::handleAssignOp(const CallEvent &Call,

                                      CheckerContext &C) const {

  ProgramStateRef State = C.getState();

  const auto *OC = dyn_cast<CXXMemberOperatorCall>(&Call);

  if (!OC)

    return false;

  OverloadedOperatorKind OOK = OC->getOverloadedOperator();

  if (OOK != OO_Equal)

    return false;

  const MemRegion *ThisRegion = OC->getCXXThisVal().getAsRegion();

  if (!ThisRegion)

    return false;

  const MemRegion *OtherSmartPtrRegion = OC->getArgSVal(0).getAsRegion();

  // In case of 'nullptr' or '0' assigned

  if (!OtherSmartPtrRegion) {

    bool AssignedNull = Call.getArgSVal(0).isZeroConstant();

    if (!AssignedNull)

      return false;

    auto NullVal = C.getSValBuilder().makeNull();

    State = State->set<TrackedRegionMap>(ThisRegion, NullVal);

    C.addTransition(State, C.getNoteTag([ThisRegion](PathSensitiveBugReport &BR,

                                                     llvm::raw_ostream &OS) {

      if (&BR.getBugType() != smartptr::getNullDereferenceBugType() ||

          !BR.isInteresting(ThisRegion))

        return;

      OS << "Smart pointer";

      checkAndPrettyPrintRegion(OS, ThisRegion);

      OS << " is assigned to null";

    }));

    return true;

  }

  return updateMovedSmartPointers(C, ThisRegion, OtherSmartPtrRegion);

}

bool SmartPtrModeling::handleMoveCtr(const CallEvent &Call, CheckerContext &C,

                                     const MemRegion *ThisRegion) const {

  const auto *OtherSmartPtrRegion = Call.getArgSVal(0).getAsRegion();

  if (!OtherSmartPtrRegion)

    return false;

  return updateMovedSmartPointers(C, ThisRegion, OtherSmartPtrRegion);

}

bool SmartPtrModeling::updateMovedSmartPointers(

    CheckerContext &C, const MemRegion *ThisRegion,

    const MemRegion *OtherSmartPtrRegion) const {

  ProgramStateRef State = C.getState();

  const auto *OtherInnerPtr = State->get<TrackedRegionMap>(OtherSmartPtrRegion);

  if (OtherInnerPtr) {

    State = State->set<TrackedRegionMap>(ThisRegion, *OtherInnerPtr);

    auto NullVal = C.getSValBuilder().makeNull();

    State = State->set<TrackedRegionMap>(OtherSmartPtrRegion, NullVal);

    bool IsArgValNull = OtherInnerPtr->isZeroConstant();

    C.addTransition(

        State,

        C.getNoteTag([ThisRegion, OtherSmartPtrRegion, IsArgValNull](

                         PathSensitiveBugReport &BR, llvm::raw_ostream &OS) {

          if (&BR.getBugType() != smartptr::getNullDereferenceBugType())

            return;

          if (BR.isInteresting(OtherSmartPtrRegion)) {

            OS << "Smart pointer";

            checkAndPrettyPrintRegion(OS, OtherSmartPtrRegion);

            OS << " is null after being moved to";

            checkAndPrettyPrintRegion(OS, ThisRegion);

          }

          if (BR.isInteresting(ThisRegion) && 
IsArgValNull5
) {

            OS << "A null pointer value is moved to";

            checkAndPrettyPrintRegion(OS, ThisRegion);

            BR.markInteresting(OtherSmartPtrRegion);

          }

        }));

    return true;

  } else {

    // In case we dont know anything about value we are moving from

    // remove the entry from map for which smart pointer got moved to.

    auto NullVal = C.getSValBuilder().makeNull();

    State = State->remove<TrackedRegionMap>(ThisRegion);

    State = State->set<TrackedRegionMap>(OtherSmartPtrRegion, NullVal);

    C.addTransition(State, C.getNoteTag([OtherSmartPtrRegion,

                                         ThisRegion](PathSensitiveBugReport &BR,

                                                     llvm::raw_ostream &OS) {

      if (&BR.getBugType() != smartptr::getNullDereferenceBugType() ||

          !BR.isInteresting(OtherSmartPtrRegion))

        return;

      OS << "Smart pointer";

      checkAndPrettyPrintRegion(OS, OtherSmartPtrRegion);

      OS << " is null after; previous value moved to";

      checkAndPrettyPrintRegion(OS, ThisRegion);

    }));

    return true;

  }

  return false;

}

void SmartPtrModeling::handleBoolConversion(const CallEvent &Call,

                                            CheckerContext &C) const {

  // To model unique_ptr::operator bool

  ProgramStateRef State = C.getState();

  const Expr *CallExpr = Call.getOriginExpr();

  const MemRegion *ThisRegion =

      cast<CXXInstanceCall>(&Call)->getCXXThisVal().getAsRegion();

  SVal InnerPointerVal;

  if (const auto *InnerValPtr = State->get<TrackedRegionMap>(ThisRegion)) {

    InnerPointerVal = *InnerValPtr;

  } else {

    // In case of inner pointer SVal is not available we create

    // conjureSymbolVal for inner pointer value.

    auto InnerPointerType = getInnerPointerType(Call, C);

    if (InnerPointerType.isNull())

      return;

    const LocationContext *LC = C.getLocationContext();

    InnerPointerVal = C.getSValBuilder().conjureSymbolVal(

        CallExpr, LC, InnerPointerType, C.blockCount());

    State = State->set<TrackedRegionMap>(ThisRegion, InnerPointerVal);

  }

  if (State->isNull(InnerPointerVal).isConstrainedTrue()) {

    State = State->BindExpr(CallExpr, C.getLocationContext(),

                            C.getSValBuilder().makeTruthVal(false));

    C.addTransition(State);

    return;

  } else if (State->isNonNull(InnerPointerVal).isConstrainedTrue()) {

    State = State->BindExpr(CallExpr, C.getLocationContext(),

                            C.getSValBuilder().makeTruthVal(true));

    C.addTransition(State);

    return;

  } else if (move::isMovedFrom(State, ThisRegion)) {

    C.addTransition(

        State->BindExpr(CallExpr, C.getLocationContext(),

                        C.getSValBuilder().makeZeroVal(Call.getResultType())));

    return;

  } else {

    ProgramStateRef NotNullState, NullState;

    std::tie(NotNullState, NullState) =

        State->assume(InnerPointerVal.castAs<DefinedOrUnknownSVal>());

    auto NullVal = C.getSValBuilder().makeNull();

    // Explicitly tracking the region as null.

    NullState = NullState->set<TrackedRegionMap>(ThisRegion, NullVal);

    NullState = NullState->BindExpr(CallExpr, C.getLocationContext(),

                                    C.getSValBuilder().makeTruthVal(false));

    C.addTransition(NullState, C.getNoteTag(

                                   [ThisRegion](PathSensitiveBugReport &BR,

                                                llvm::raw_ostream &OS) {

                                     OS << "Assuming smart pointer";

                                     checkAndPrettyPrintRegion(OS, ThisRegion);

                                     OS << " is null";

                                   },

                                   /*IsPrunable=*/true));

    NotNullState =

        NotNullState->BindExpr(CallExpr, C.getLocationContext(),

                               C.getSValBuilder().makeTruthVal(true));

    C.addTransition(

        NotNullState,

        C.getNoteTag(

            [ThisRegion](PathSensitiveBugReport &BR, llvm::raw_ostream &OS) {

              OS << "Assuming smart pointer";

              checkAndPrettyPrintRegion(OS, ThisRegion);

              OS << " is non-null";

            },

            /*IsPrunable=*/true));

    return;

  }

}

void ento::registerSmartPtrModeling(CheckerManager &Mgr) {

  auto *Checker = Mgr.registerChecker<SmartPtrModeling>();

  Checker->ModelSmartPtrDereference =

      Mgr.getAnalyzerOptions().getCheckerBooleanOption(

          Checker, "ModelSmartPtrDereference");

}

bool ento::shouldRegisterSmartPtrModeling(const CheckerManager &mgr) {

  const LangOptions &LO = mgr.getLangOpts();

  return LO.CPlusPlus;

}