1 files changed, 763 insertions, 0 deletions
diff --git a/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp
new file mode 100644
index 000000000000..3e46e2372516
--- /dev/null
+++ b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp
@@ -0,0 +1,763 @@
+//===--- CallAndMessageChecker.cpp ------------------------------*- 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 defines CallAndMessageChecker, a builtin checker that checks for various
+// errors of call and objc message expressions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/ParentMap.h"
+#include "clang/Basic/TargetInfo.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 "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+
+class CallAndMessageChecker
+    : public Checker<check::PreObjCMessage, check::ObjCMessageNil,
+                     check::PreCall> {
+  mutable std::unique_ptr<BugType> BT_call_null;
+  mutable std::unique_ptr<BugType> BT_call_undef;
+  mutable std::unique_ptr<BugType> BT_cxx_call_null;
+  mutable std::unique_ptr<BugType> BT_cxx_call_undef;
+  mutable std::unique_ptr<BugType> BT_call_arg;
+  mutable std::unique_ptr<BugType> BT_cxx_delete_undef;
+  mutable std::unique_ptr<BugType> BT_msg_undef;
+  mutable std::unique_ptr<BugType> BT_objc_prop_undef;
+  mutable std::unique_ptr<BugType> BT_objc_subscript_undef;
+  mutable std::unique_ptr<BugType> BT_msg_arg;
+  mutable std::unique_ptr<BugType> BT_msg_ret;
+  mutable std::unique_ptr<BugType> BT_call_few_args;
+
+public:
+  // These correspond with the checker options. Looking at other checkers such
+  // as MallocChecker and CStringChecker, this is similar as to how they pull
+  // off having a modeling class, but emitting diagnostics under a smaller
+  // checker's name that can be safely disabled without disturbing the
+  // underlaying modeling engine.
+  // The reason behind having *checker options* rather then actual *checkers*
+  // here is that CallAndMessage is among the oldest checkers out there, and can
+  // be responsible for the majority of the reports on any given project. This
+  // is obviously not ideal, but changing checker name has the consequence of
+  // changing the issue hashes associated with the reports, and databases
+  // relying on this (CodeChecker, for instance) would suffer greatly.
+  // If we ever end up making changes to the issue hash generation algorithm, or
+  // the warning messages here, we should totally jump on the opportunity to
+  // convert these to actual checkers.
+  enum CheckKind {
+    CK_FunctionPointer,
+    CK_ParameterCount,
+    CK_CXXThisMethodCall,
+    CK_CXXDeallocationArg,
+    CK_ArgInitializedness,
+    CK_ArgPointeeInitializedness,
+    CK_NilReceiver,
+    CK_UndefReceiver,
+    CK_NumCheckKinds
+  };
+
+  DefaultBool ChecksEnabled[CK_NumCheckKinds];
+  // The original core.CallAndMessage checker name. This should rather be an
+  // array, as seen in MallocChecker and CStringChecker.
+  CheckerNameRef OriginalName;
+
+  void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
+
+  /// Fill in the return value that results from messaging nil based on the
+  /// return type and architecture and diagnose if the return value will be
+  /// garbage.
+  void checkObjCMessageNil(const ObjCMethodCall &msg, CheckerContext &C) const;
+
+  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
+
+  ProgramStateRef checkFunctionPointerCall(const CallExpr *CE,
+                                           CheckerContext &C,
+                                           ProgramStateRef State) const;
+
+  ProgramStateRef checkCXXMethodCall(const CXXInstanceCall *CC,
+                                     CheckerContext &C,
+                                     ProgramStateRef State) const;
+
+  ProgramStateRef checkParameterCount(const CallEvent &Call, CheckerContext &C,
+                                      ProgramStateRef State) const;
+
+  ProgramStateRef checkCXXDeallocation(const CXXDeallocatorCall *DC,
+                                       CheckerContext &C,
+                                       ProgramStateRef State) const;
+
+  ProgramStateRef checkArgInitializedness(const CallEvent &Call,
+                                          CheckerContext &C,
+                                          ProgramStateRef State) const;
+
+private:
+  bool PreVisitProcessArg(CheckerContext &C, SVal V, SourceRange ArgRange,
+                          const Expr *ArgEx, int ArgumentNumber,
+                          bool CheckUninitFields, const CallEvent &Call,
+                          std::unique_ptr<BugType> &BT,
+                          const ParmVarDecl *ParamDecl) const;
+
+  static void emitBadCall(BugType *BT, CheckerContext &C, const Expr *BadE);
+  void emitNilReceiverBug(CheckerContext &C, const ObjCMethodCall &msg,
+                          ExplodedNode *N) const;
+
+  void HandleNilReceiver(CheckerContext &C,
+                         ProgramStateRef state,
+                         const ObjCMethodCall &msg) const;
+
+  void LazyInit_BT(const char *desc, std::unique_ptr<BugType> &BT) const {
+    if (!BT)
+      BT.reset(new BuiltinBug(OriginalName, desc));
+  }
+  bool uninitRefOrPointer(CheckerContext &C, const SVal &V,
+                          SourceRange ArgRange, const Expr *ArgEx,
+                          std::unique_ptr<BugType> &BT,
+                          const ParmVarDecl *ParamDecl, const char *BD,
+                          int ArgumentNumber) const;
+};
+} // end anonymous namespace
+
+void CallAndMessageChecker::emitBadCall(BugType *BT, CheckerContext &C,
+                                        const Expr *BadE) {
+  ExplodedNode *N = C.generateErrorNode();
+  if (!N)
+    return;
+
+  auto R = std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N);
+  if (BadE) {
+    R->addRange(BadE->getSourceRange());
+    if (BadE->isGLValue())
+      BadE = bugreporter::getDerefExpr(BadE);
+    bugreporter::trackExpressionValue(N, BadE, *R);
+  }
+  C.emitReport(std::move(R));
+}
+
+static void describeUninitializedArgumentInCall(const CallEvent &Call,
+                                                int ArgumentNumber,
+                                                llvm::raw_svector_ostream &Os) {
+  switch (Call.getKind()) {
+  case CE_ObjCMessage: {
+    const ObjCMethodCall &Msg = cast<ObjCMethodCall>(Call);
+    switch (Msg.getMessageKind()) {
+    case OCM_Message:
+      Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
+         << " argument in message expression is an uninitialized value";
+      return;
+    case OCM_PropertyAccess:
+      assert(Msg.isSetter() && "Getters have no args");
+      Os << "Argument for property setter is an uninitialized value";
+      return;
+    case OCM_Subscript:
+      if (Msg.isSetter() && (ArgumentNumber == 0))
+        Os << "Argument for subscript setter is an uninitialized value";
+      else
+        Os << "Subscript index is an uninitialized value";
+      return;
+    }
+    llvm_unreachable("Unknown message kind.");
+  }
+  case CE_Block:
+    Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
+       << " block call argument is an uninitialized value";
+    return;
+  default:
+    Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
+       << " function call argument is an uninitialized value";
+    return;
+  }
+}
+
+bool CallAndMessageChecker::uninitRefOrPointer(
+    CheckerContext &C, const SVal &V, SourceRange ArgRange, const Expr *ArgEx,
+    std::unique_ptr<BugType> &BT, const ParmVarDecl *ParamDecl, const char *BD,
+    int ArgumentNumber) const {
+
+  // The pointee being uninitialized is a sign of code smell, not a bug, no need
+  // to sink here.
+  if (!ChecksEnabled[CK_ArgPointeeInitializedness])
+    return false;
+
+  // No parameter declaration available, i.e. variadic function argument.
+  if(!ParamDecl)
+    return false;
+
+  // If parameter is declared as pointer to const in function declaration,
+  // then check if corresponding argument in function call is
+  // pointing to undefined symbol value (uninitialized memory).
+  SmallString<200> Buf;
+  llvm::raw_svector_ostream Os(Buf);
+
+  if (ParamDecl->getType()->isPointerType()) {
+    Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
+       << " function call argument is a pointer to uninitialized value";
+  } else if (ParamDecl->getType()->isReferenceType()) {
+    Os << (ArgumentNumber + 1) << llvm::getOrdinalSuffix(ArgumentNumber + 1)
+       << " function call argument is an uninitialized value";
+  } else
+    return false;
+
+  if(!ParamDecl->getType()->getPointeeType().isConstQualified())
+    return false;
+
+  if (const MemRegion *SValMemRegion = V.getAsRegion()) {
+    const ProgramStateRef State = C.getState();
+    const SVal PSV = State->getSVal(SValMemRegion, C.getASTContext().CharTy);
+    if (PSV.isUndef()) {
+      if (ExplodedNode *N = C.generateErrorNode()) {
+        LazyInit_BT(BD, BT);
+        auto R = std::make_unique<PathSensitiveBugReport>(*BT, Os.str(), N);
+        R->addRange(ArgRange);
+        if (ArgEx)
+          bugreporter::trackExpressionValue(N, ArgEx, *R);
+
+        C.emitReport(std::move(R));
+      }
+      return true;
+    }
+  }
+  return false;
+}
+
+namespace {
+class FindUninitializedField {
+public:
+  SmallVector<const FieldDecl *, 10> FieldChain;
+
+private:
+  StoreManager &StoreMgr;
+  MemRegionManager &MrMgr;
+  Store store;
+
+public:
+  FindUninitializedField(StoreManager &storeMgr, MemRegionManager &mrMgr,
+                         Store s)
+      : StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {}
+
+  bool Find(const TypedValueRegion *R) {
+    QualType T = R->getValueType();
+    if (const RecordType *RT = T->getAsStructureType()) {
+      const RecordDecl *RD = RT->getDecl()->getDefinition();
+      assert(RD && "Referred record has no definition");
+      for (const auto *I : RD->fields()) {
+        const FieldRegion *FR = MrMgr.getFieldRegion(I, R);
+        FieldChain.push_back(I);
+        T = I->getType();
+        if (T->getAsStructureType()) {
+          if (Find(FR))
+            return true;
+        } else {
+          const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR));
+          if (V.isUndef())
+            return true;
+        }
+        FieldChain.pop_back();
+      }
+    }
+
+    return false;
+  }
+};
+} // namespace
+
+bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
+                                               SVal V,
+                                               SourceRange ArgRange,
+                                               const Expr *ArgEx,
+                                               int ArgumentNumber,
+                                               bool CheckUninitFields,
+                                               const CallEvent &Call,
+                                               std::unique_ptr<BugType> &BT,
+                                               const ParmVarDecl *ParamDecl
+                                               ) const {
+  const char *BD = "Uninitialized argument value";
+
+  if (uninitRefOrPointer(C, V, ArgRange, ArgEx, BT, ParamDecl, BD,
+                         ArgumentNumber))
+    return true;
+
+  if (V.isUndef()) {
+    if (!ChecksEnabled[CK_ArgInitializedness]) {
+      C.addSink();
+      return true;
+    }
+    if (ExplodedNode *N = C.generateErrorNode()) {
+      LazyInit_BT(BD, BT);
+      // Generate a report for this bug.
+      SmallString<200> Buf;
+      llvm::raw_svector_ostream Os(Buf);
+      describeUninitializedArgumentInCall(Call, ArgumentNumber, Os);
+      auto R = std::make_unique<PathSensitiveBugReport>(*BT, Os.str(), N);
+
+      R->addRange(ArgRange);
+      if (ArgEx)
+        bugreporter::trackExpressionValue(N, ArgEx, *R);
+      C.emitReport(std::move(R));
+    }
+    return true;
+  }
+
+  if (!CheckUninitFields)
+    return false;
+
+  if (auto LV = V.getAs<nonloc::LazyCompoundVal>()) {
+    const LazyCompoundValData *D = LV->getCVData();
+    FindUninitializedField F(C.getState()->getStateManager().getStoreManager(),
+                             C.getSValBuilder().getRegionManager(),
+                             D->getStore());
+
+    if (F.Find(D->getRegion())) {
+      if (!ChecksEnabled[CK_ArgInitializedness]) {
+        C.addSink();
+        return true;
+      }
+      if (ExplodedNode *N = C.generateErrorNode()) {
+        LazyInit_BT(BD, BT);
+        SmallString<512> Str;
+        llvm::raw_svector_ostream os(Str);
+        os << "Passed-by-value struct argument contains uninitialized data";
+
+        if (F.FieldChain.size() == 1)
+          os << " (e.g., field: '" << *F.FieldChain[0] << "')";
+        else {
+          os << " (e.g., via the field chain: '";
+          bool first = true;
+          for (SmallVectorImpl<const FieldDecl *>::iterator
+               DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){
+            if (first)
+              first = false;
+            else
+              os << '.';
+            os << **DI;
+          }
+          os << "')";
+        }
+
+        // Generate a report for this bug.
+        auto R = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N);
+        R->addRange(ArgRange);
+
+        if (ArgEx)
+          bugreporter::trackExpressionValue(N, ArgEx, *R);
+        // FIXME: enhance track back for uninitialized value for arbitrary
+        // memregions
+        C.emitReport(std::move(R));
+      }
+      return true;
+    }
+  }
+
+  return false;
+}
+
+ProgramStateRef CallAndMessageChecker::checkFunctionPointerCall(
+    const CallExpr *CE, CheckerContext &C, ProgramStateRef State) const {
+
+  const Expr *Callee = CE->getCallee()->IgnoreParens();
+  const LocationContext *LCtx = C.getLocationContext();
+  SVal L = State->getSVal(Callee, LCtx);
+
+  if (L.isUndef()) {
+    if (!ChecksEnabled[CK_FunctionPointer]) {
+      C.addSink(State);
+      return nullptr;
+    }
+    if (!BT_call_undef)
+      BT_call_undef.reset(new BuiltinBug(
+          OriginalName,
+          "Called function pointer is an uninitialized pointer value"));
+    emitBadCall(BT_call_undef.get(), C, Callee);
+    return nullptr;
+  }
+
+  ProgramStateRef StNonNull, StNull;
+  std::tie(StNonNull, StNull) = State->assume(L.castAs<DefinedOrUnknownSVal>());
+
+  if (StNull && !StNonNull) {
+    if (!ChecksEnabled[CK_FunctionPointer]) {
+      C.addSink(StNull);
+      return nullptr;
+    }
+    if (!BT_call_null)
+      BT_call_null.reset(new BuiltinBug(
+          OriginalName, "Called function pointer is null (null dereference)"));
+    emitBadCall(BT_call_null.get(), C, Callee);
+    return nullptr;
+  }
+
+  return StNonNull;
+}
+
+ProgramStateRef CallAndMessageChecker::checkParameterCount(
+    const CallEvent &Call, CheckerContext &C, ProgramStateRef State) const {
+
+  // If we have a function or block declaration, we can make sure we pass
+  // enough parameters.
+  unsigned Params = Call.parameters().size();
+  if (Call.getNumArgs() >= Params)
+    return State;
+
+  if (!ChecksEnabled[CK_ParameterCount]) {
+    C.addSink(State);
+    return nullptr;
+  }
+
+  ExplodedNode *N = C.generateErrorNode();
+  if (!N)
+    return nullptr;
+
+  LazyInit_BT("Function call with too few arguments", BT_call_few_args);
+
+  SmallString<512> Str;
+  llvm::raw_svector_ostream os(Str);
+  if (isa<AnyFunctionCall>(Call)) {
+    os << "Function ";
+  } else {
+    assert(isa<BlockCall>(Call));
+    os << "Block ";
+  }
+  os << "taking " << Params << " argument" << (Params == 1 ? "" : "s")
+     << " is called with fewer (" << Call.getNumArgs() << ")";
+
+  C.emitReport(
+      std::make_unique<PathSensitiveBugReport>(*BT_call_few_args, os.str(), N));
+  return nullptr;
+}
+
+ProgramStateRef CallAndMessageChecker::checkCXXMethodCall(
+    const CXXInstanceCall *CC, CheckerContext &C, ProgramStateRef State) const {
+
+  SVal V = CC->getCXXThisVal();
+  if (V.isUndef()) {
+    if (!ChecksEnabled[CK_CXXThisMethodCall]) {
+      C.addSink(State);
+      return nullptr;
+    }
+    if (!BT_cxx_call_undef)
+      BT_cxx_call_undef.reset(new BuiltinBug(
+          OriginalName, "Called C++ object pointer is uninitialized"));
+    emitBadCall(BT_cxx_call_undef.get(), C, CC->getCXXThisExpr());
+    return nullptr;
+  }
+
+  ProgramStateRef StNonNull, StNull;
+  std::tie(StNonNull, StNull) = State->assume(V.castAs<DefinedOrUnknownSVal>());
+
+  if (StNull && !StNonNull) {
+    if (!ChecksEnabled[CK_CXXThisMethodCall]) {
+      C.addSink(StNull);
+      return nullptr;
+    }
+    if (!BT_cxx_call_null)
+      BT_cxx_call_null.reset(
+          new BuiltinBug(OriginalName, "Called C++ object pointer is null"));
+    emitBadCall(BT_cxx_call_null.get(), C, CC->getCXXThisExpr());
+    return nullptr;
+  }
+
+  return StNonNull;
+}
+
+ProgramStateRef
+CallAndMessageChecker::checkCXXDeallocation(const CXXDeallocatorCall *DC,
+                                            CheckerContext &C,
+                                            ProgramStateRef State) const {
+  const CXXDeleteExpr *DE = DC->getOriginExpr();
+  assert(DE);
+  SVal Arg = C.getSVal(DE->getArgument());
+  if (!Arg.isUndef())
+    return State;
+
+  if (!ChecksEnabled[CK_CXXDeallocationArg]) {
+    C.addSink(State);
+    return nullptr;
+  }
+
+  StringRef Desc;
+  ExplodedNode *N = C.generateErrorNode();
+  if (!N)
+    return nullptr;
+  if (!BT_cxx_delete_undef)
+    BT_cxx_delete_undef.reset(
+        new BuiltinBug(OriginalName, "Uninitialized argument value"));
+  if (DE->isArrayFormAsWritten())
+    Desc = "Argument to 'delete[]' is uninitialized";
+  else
+    Desc = "Argument to 'delete' is uninitialized";
+  BugType *BT = BT_cxx_delete_undef.get();
+  auto R = std::make_unique<PathSensitiveBugReport>(*BT, Desc, N);
+  bugreporter::trackExpressionValue(N, DE, *R);
+  C.emitReport(std::move(R));
+  return nullptr;
+}
+
+ProgramStateRef CallAndMessageChecker::checkArgInitializedness(
+    const CallEvent &Call, CheckerContext &C, ProgramStateRef State) const {
+
+  const Decl *D = Call.getDecl();
+
+  // Don't check for uninitialized field values in arguments if the
+  // caller has a body that is available and we have the chance to inline it.
+  // This is a hack, but is a reasonable compromise betweens sometimes warning
+  // and sometimes not depending on if we decide to inline a function.
+  const bool checkUninitFields =
+      !(C.getAnalysisManager().shouldInlineCall() && (D && D->getBody()));
+
+  std::unique_ptr<BugType> *BT;
+  if (isa<ObjCMethodCall>(Call))
+    BT = &BT_msg_arg;
+  else
+    BT = &BT_call_arg;
+
+  const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
+  for (unsigned i = 0, e = Call.getNumArgs(); i != e; ++i) {
+    const ParmVarDecl *ParamDecl = nullptr;
+    if (FD && i < FD->getNumParams())
+      ParamDecl = FD->getParamDecl(i);
+    if (PreVisitProcessArg(C, Call.getArgSVal(i), Call.getArgSourceRange(i),
+                           Call.getArgExpr(i), i, checkUninitFields, Call, *BT,
+                           ParamDecl))
+      return nullptr;
+  }
+  return State;
+}
+
+void CallAndMessageChecker::checkPreCall(const CallEvent &Call,
+                                         CheckerContext &C) const {
+  ProgramStateRef State = C.getState();
+
+  if (const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr()))
+    State = checkFunctionPointerCall(CE, C, State);
+
+  if (!State)
+    return;
+
+  if (Call.getDecl())
+    State = checkParameterCount(Call, C, State);
+
+  if (!State)
+    return;
+
+  if (const auto *CC = dyn_cast<CXXInstanceCall>(&Call))
+    State = checkCXXMethodCall(CC, C, State);
+
+  if (!State)
+    return;
+
+  if (const auto *DC = dyn_cast<CXXDeallocatorCall>(&Call))
+    State = checkCXXDeallocation(DC, C, State);
+
+  if (!State)
+    return;
+
+  State = checkArgInitializedness(Call, C, State);
+
+  // If we make it here, record our assumptions about the callee.
+  C.addTransition(State);
+}
+
+void CallAndMessageChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
+                                                CheckerContext &C) const {
+  SVal recVal = msg.getReceiverSVal();
+  if (recVal.isUndef()) {
+    if (!ChecksEnabled[CK_UndefReceiver]) {
+      C.addSink();
+      return;
+    }
+    if (ExplodedNode *N = C.generateErrorNode()) {
+      BugType *BT = nullptr;
+      switch (msg.getMessageKind()) {
+      case OCM_Message:
+        if (!BT_msg_undef)
+          BT_msg_undef.reset(new BuiltinBug(OriginalName,
+                                            "Receiver in message expression "
+                                            "is an uninitialized value"));
+        BT = BT_msg_undef.get();
+        break;
+      case OCM_PropertyAccess:
+        if (!BT_objc_prop_undef)
+          BT_objc_prop_undef.reset(new BuiltinBug(
+              OriginalName,
+              "Property access on an uninitialized object pointer"));
+        BT = BT_objc_prop_undef.get();
+        break;
+      case OCM_Subscript:
+        if (!BT_objc_subscript_undef)
+          BT_objc_subscript_undef.reset(new BuiltinBug(
+              OriginalName,
+              "Subscript access on an uninitialized object pointer"));
+        BT = BT_objc_subscript_undef.get();
+        break;
+      }
+      assert(BT && "Unknown message kind.");
+
+      auto R = std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N);
+      const ObjCMessageExpr *ME = msg.getOriginExpr();
+      R->addRange(ME->getReceiverRange());
+
+      // FIXME: getTrackNullOrUndefValueVisitor can't handle "super" yet.
+      if (const Expr *ReceiverE = ME->getInstanceReceiver())
+        bugreporter::trackExpressionValue(N, ReceiverE, *R);
+      C.emitReport(std::move(R));
+    }
+    return;
+  }
+}
+
+void CallAndMessageChecker::checkObjCMessageNil(const ObjCMethodCall &msg,
+                                                CheckerContext &C) const {
+  HandleNilReceiver(C, C.getState(), msg);
+}
+
+void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
+                                               const ObjCMethodCall &msg,
+                                               ExplodedNode *N) const {
+  if (!ChecksEnabled[CK_NilReceiver]) {
+    C.addSink();
+    return;
+  }
+
+  if (!BT_msg_ret)
+    BT_msg_ret.reset(new BuiltinBug(OriginalName,
+                                    "Receiver in message expression is 'nil'"));
+
+  const ObjCMessageExpr *ME = msg.getOriginExpr();
+
+  QualType ResTy = msg.getResultType();
+
+  SmallString<200> buf;
+  llvm::raw_svector_ostream os(buf);
+  os << "The receiver of message '";
+  ME->getSelector().print(os);
+  os << "' is nil";
+  if (ResTy->isReferenceType()) {
+    os << ", which results in forming a null reference";
+  } else {
+    os << " and returns a value of type '";
+    msg.getResultType().print(os, C.getLangOpts());
+    os << "' that will be garbage";
+  }
+
+  auto report =
+      std::make_unique<PathSensitiveBugReport>(*BT_msg_ret, os.str(), N);
+  report->addRange(ME->getReceiverRange());
+  // FIXME: This won't track "self" in messages to super.
+  if (const Expr *receiver = ME->getInstanceReceiver()) {
+    bugreporter::trackExpressionValue(N, receiver, *report);
+  }
+  C.emitReport(std::move(report));
+}
+
+static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
+  return (triple.getVendor() == llvm::Triple::Apple &&
+          (triple.isiOS() || triple.isWatchOS() ||
+           !triple.isMacOSXVersionLT(10,5)));
+}
+
+void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
+                                              ProgramStateRef state,
+                                              const ObjCMethodCall &Msg) const {
+  ASTContext &Ctx = C.getASTContext();
+  static CheckerProgramPointTag Tag(this, "NilReceiver");
+
+  // Check the return type of the message expression.  A message to nil will
+  // return different values depending on the return type and the architecture.
+  QualType RetTy = Msg.getResultType();
+  CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
+  const LocationContext *LCtx = C.getLocationContext();
+
+  if (CanRetTy->isStructureOrClassType()) {
+    // Structure returns are safe since the compiler zeroes them out.
+    SVal V = C.getSValBuilder().makeZeroVal(RetTy);
+    C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
+    return;
+  }
+
+  // Other cases: check if sizeof(return type) > sizeof(void*)
+  if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap()
+                                  .isConsumedExpr(Msg.getOriginExpr())) {
+    // Compute: sizeof(void *) and sizeof(return type)
+    const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
+    const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
+
+    if (CanRetTy.getTypePtr()->isReferenceType()||
+        (voidPtrSize < returnTypeSize &&
+         !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) &&
+           (Ctx.FloatTy == CanRetTy ||
+            Ctx.DoubleTy == CanRetTy ||
+            Ctx.LongDoubleTy == CanRetTy ||
+            Ctx.LongLongTy == CanRetTy ||
+            Ctx.UnsignedLongLongTy == CanRetTy)))) {
+      if (ExplodedNode *N = C.generateErrorNode(state, &Tag))
+        emitNilReceiverBug(C, Msg, N);
+      return;
+    }
+
+    // Handle the safe cases where the return value is 0 if the
+    // receiver is nil.
+    //
+    // FIXME: For now take the conservative approach that we only
+    // return null values if we *know* that the receiver is nil.
+    // This is because we can have surprises like:
+    //
+    //   ... = [[NSScreens screens] objectAtIndex:0];
+    //
+    // What can happen is that [... screens] could return nil, but
+    // it most likely isn't nil.  We should assume the semantics
+    // of this case unless we have *a lot* more knowledge.
+    //
+    SVal V = C.getSValBuilder().makeZeroVal(RetTy);
+    C.addTransition(state->BindExpr(Msg.getOriginExpr(), LCtx, V), &Tag);
+    return;
+  }
+
+  C.addTransition(state);
+}
+
+void ento::registerCallAndMessageModeling(CheckerManager &mgr) {
+  mgr.registerChecker<CallAndMessageChecker>();
+}
+
+bool ento::shouldRegisterCallAndMessageModeling(const CheckerManager &mgr) {
+  return true;
+}
+
+void ento::registerCallAndMessageChecker(CheckerManager &mgr) {
+  CallAndMessageChecker *checker = mgr.getChecker<CallAndMessageChecker>();
+
+  checker->OriginalName = mgr.getCurrentCheckerName();
+
+#define QUERY_CHECKER_OPTION(OPTION)                                           \
+  checker->ChecksEnabled[CallAndMessageChecker::CK_##OPTION] =                 \
+      mgr.getAnalyzerOptions().getCheckerBooleanOption(                        \
+          mgr.getCurrentCheckerName(), #OPTION);
+
+  QUERY_CHECKER_OPTION(FunctionPointer)
+  QUERY_CHECKER_OPTION(ParameterCount)
+  QUERY_CHECKER_OPTION(CXXThisMethodCall)
+  QUERY_CHECKER_OPTION(CXXDeallocationArg)
+  QUERY_CHECKER_OPTION(ArgInitializedness)
+  QUERY_CHECKER_OPTION(ArgPointeeInitializedness)
+  QUERY_CHECKER_OPTION(NilReceiver)
+  QUERY_CHECKER_OPTION(UndefReceiver)
+}
+
+bool ento::shouldRegisterCallAndMessageChecker(const CheckerManager &mgr) {
+  return true;
+}