Export clang-format16 via ydblib project

6e6be3a95868fde888d801b7590af4044049563f

1 files changed, 1297 insertions, 0 deletions

diff --git a/contrib/libs/clang16/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp b/contrib/libs/clang16/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
new file mode 100644
index 0000000000..44166aaf5b
--- /dev/null
+++ b/contrib/libs/clang16/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
@@ -0,0 +1,1297 @@
+//== BasicObjCFoundationChecks.cpp - Simple Apple-Foundation checks -*- 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 BasicObjCFoundationChecks, a class that encapsulates
+//  a set of simple checks to run on Objective-C code using Apple's Foundation
+//  classes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/AST/StmtObjC.h"
+#include "clang/Analysis/DomainSpecific/CocoaConventions.h"
+#include "clang/Analysis/SelectorExtras.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/CallDescription.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/Support/raw_ostream.h"
+#include <optional>
+
+using namespace clang;
+using namespace ento;
+using namespace llvm;
+
+namespace {
+class APIMisuse : public BugType {
+public:
+  APIMisuse(const CheckerBase *checker, const char *name)
+      : BugType(checker, name, "API Misuse (Apple)") {}
+};
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
+// Utility functions.
+//===----------------------------------------------------------------------===//
+
+static StringRef GetReceiverInterfaceName(const ObjCMethodCall &msg) {
+  if (const ObjCInterfaceDecl *ID = msg.getReceiverInterface())
+    return ID->getIdentifier()->getName();
+  return StringRef();
+}
+
+enum FoundationClass {
+  FC_None,
+  FC_NSArray,
+  FC_NSDictionary,
+  FC_NSEnumerator,
+  FC_NSNull,
+  FC_NSOrderedSet,
+  FC_NSSet,
+  FC_NSString
+};
+
+static FoundationClass findKnownClass(const ObjCInterfaceDecl *ID,
+                                      bool IncludeSuperclasses = true) {
+  static llvm::StringMap<FoundationClass> Classes;
+  if (Classes.empty()) {
+    Classes["NSArray"] = FC_NSArray;
+    Classes["NSDictionary"] = FC_NSDictionary;
+    Classes["NSEnumerator"] = FC_NSEnumerator;
+    Classes["NSNull"] = FC_NSNull;
+    Classes["NSOrderedSet"] = FC_NSOrderedSet;
+    Classes["NSSet"] = FC_NSSet;
+    Classes["NSString"] = FC_NSString;
+  }
+
+  // FIXME: Should we cache this at all?
+  FoundationClass result = Classes.lookup(ID->getIdentifier()->getName());
+  if (result == FC_None && IncludeSuperclasses)
+    if (const ObjCInterfaceDecl *Super = ID->getSuperClass())
+      return findKnownClass(Super);
+
+  return result;
+}
+
+//===----------------------------------------------------------------------===//
+// NilArgChecker - Check for prohibited nil arguments to ObjC method calls.
+//===----------------------------------------------------------------------===//
+
+namespace {
+  class NilArgChecker : public Checker<check::PreObjCMessage,
+                                       check::PostStmt<ObjCDictionaryLiteral>,
+                                       check::PostStmt<ObjCArrayLiteral> > {
+    mutable std::unique_ptr<APIMisuse> BT;
+
+    mutable llvm::SmallDenseMap<Selector, unsigned, 16> StringSelectors;
+    mutable Selector ArrayWithObjectSel;
+    mutable Selector AddObjectSel;
+    mutable Selector InsertObjectAtIndexSel;
+    mutable Selector ReplaceObjectAtIndexWithObjectSel;
+    mutable Selector SetObjectAtIndexedSubscriptSel;
+    mutable Selector ArrayByAddingObjectSel;
+    mutable Selector DictionaryWithObjectForKeySel;
+    mutable Selector SetObjectForKeySel;
+    mutable Selector SetObjectForKeyedSubscriptSel;
+    mutable Selector RemoveObjectForKeySel;
+
+    void warnIfNilExpr(const Expr *E,
+                       const char *Msg,
+                       CheckerContext &C) const;
+
+    void warnIfNilArg(CheckerContext &C,
+                      const ObjCMethodCall &msg, unsigned Arg,
+                      FoundationClass Class,
+                      bool CanBeSubscript = false) const;
+
+    void generateBugReport(ExplodedNode *N,
+                           StringRef Msg,
+                           SourceRange Range,
+                           const Expr *Expr,
+                           CheckerContext &C) const;
+
+  public:
+    void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
+    void checkPostStmt(const ObjCDictionaryLiteral *DL,
+                       CheckerContext &C) const;
+    void checkPostStmt(const ObjCArrayLiteral *AL,
+                       CheckerContext &C) const;
+  };
+} // end anonymous namespace
+
+void NilArgChecker::warnIfNilExpr(const Expr *E,
+                                  const char *Msg,
+                                  CheckerContext &C) const {
+  ProgramStateRef State = C.getState();
+  if (State->isNull(C.getSVal(E)).isConstrainedTrue()) {
+
+    if (ExplodedNode *N = C.generateErrorNode()) {
+      generateBugReport(N, Msg, E->getSourceRange(), E, C);
+    }
+  }
+}
+
+void NilArgChecker::warnIfNilArg(CheckerContext &C,
+                                 const ObjCMethodCall &msg,
+                                 unsigned int Arg,
+                                 FoundationClass Class,
+                                 bool CanBeSubscript) const {
+  // Check if the argument is nil.
+  ProgramStateRef State = C.getState();
+  if (!State->isNull(msg.getArgSVal(Arg)).isConstrainedTrue())
+      return;
+
+  // NOTE: We cannot throw non-fatal errors from warnIfNilExpr,
+  // because it's called multiple times from some callers, so it'd cause
+  // an unwanted state split if two or more non-fatal errors are thrown
+  // within the same checker callback. For now we don't want to, but
+  // it'll need to be fixed if we ever want to.
+  if (ExplodedNode *N = C.generateErrorNode()) {
+    SmallString<128> sbuf;
+    llvm::raw_svector_ostream os(sbuf);
+
+    if (CanBeSubscript && msg.getMessageKind() == OCM_Subscript) {
+
+      if (Class == FC_NSArray) {
+        os << "Array element cannot be nil";
+      } else if (Class == FC_NSDictionary) {
+        if (Arg == 0) {
+          os << "Value stored into '";
+          os << GetReceiverInterfaceName(msg) << "' cannot be nil";
+        } else {
+          assert(Arg == 1);
+          os << "'"<< GetReceiverInterfaceName(msg) << "' key cannot be nil";
+        }
+      } else
+        llvm_unreachable("Missing foundation class for the subscript expr");
+
+    } else {
+      if (Class == FC_NSDictionary) {
+        if (Arg == 0)
+          os << "Value argument ";
+        else {
+          assert(Arg == 1);
+          os << "Key argument ";
+        }
+        os << "to '";
+        msg.getSelector().print(os);
+        os << "' cannot be nil";
+      } else {
+        os << "Argument to '" << GetReceiverInterfaceName(msg) << "' method '";
+        msg.getSelector().print(os);
+        os << "' cannot be nil";
+      }
+    }
+
+    generateBugReport(N, os.str(), msg.getArgSourceRange(Arg),
+                      msg.getArgExpr(Arg), C);
+  }
+}
+
+void NilArgChecker::generateBugReport(ExplodedNode *N,
+                                      StringRef Msg,
+                                      SourceRange Range,
+                                      const Expr *E,
+                                      CheckerContext &C) const {
+  if (!BT)
+    BT.reset(new APIMisuse(this, "nil argument"));
+
+  auto R = std::make_unique<PathSensitiveBugReport>(*BT, Msg, N);
+  R->addRange(Range);
+  bugreporter::trackExpressionValue(N, E, *R);
+  C.emitReport(std::move(R));
+}
+
+void NilArgChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
+                                        CheckerContext &C) const {
+  const ObjCInterfaceDecl *ID = msg.getReceiverInterface();
+  if (!ID)
+    return;
+
+  FoundationClass Class = findKnownClass(ID);
+
+  static const unsigned InvalidArgIndex = UINT_MAX;
+  unsigned Arg = InvalidArgIndex;
+  bool CanBeSubscript = false;
+
+  if (Class == FC_NSString) {
+    Selector S = msg.getSelector();
+
+    if (S.isUnarySelector())
+      return;
+
+    if (StringSelectors.empty()) {
+      ASTContext &Ctx = C.getASTContext();
+      Selector Sels[] = {
+          getKeywordSelector(Ctx, "caseInsensitiveCompare"),
+          getKeywordSelector(Ctx, "compare"),
+          getKeywordSelector(Ctx, "compare", "options"),
+          getKeywordSelector(Ctx, "compare", "options", "range"),
+          getKeywordSelector(Ctx, "compare", "options", "range", "locale"),
+          getKeywordSelector(Ctx, "componentsSeparatedByCharactersInSet"),
+          getKeywordSelector(Ctx, "initWithFormat"),
+          getKeywordSelector(Ctx, "localizedCaseInsensitiveCompare"),
+          getKeywordSelector(Ctx, "localizedCompare"),
+          getKeywordSelector(Ctx, "localizedStandardCompare"),
+      };
+      for (Selector KnownSel : Sels)
+        StringSelectors[KnownSel] = 0;
+    }
+    auto I = StringSelectors.find(S);
+    if (I == StringSelectors.end())
+      return;
+    Arg = I->second;
+  } else if (Class == FC_NSArray) {
+    Selector S = msg.getSelector();
+
+    if (S.isUnarySelector())
+      return;
+
+    if (ArrayWithObjectSel.isNull()) {
+      ASTContext &Ctx = C.getASTContext();
+      ArrayWithObjectSel = getKeywordSelector(Ctx, "arrayWithObject");
+      AddObjectSel = getKeywordSelector(Ctx, "addObject");
+      InsertObjectAtIndexSel =
+          getKeywordSelector(Ctx, "insertObject", "atIndex");
+      ReplaceObjectAtIndexWithObjectSel =
+          getKeywordSelector(Ctx, "replaceObjectAtIndex", "withObject");
+      SetObjectAtIndexedSubscriptSel =
+          getKeywordSelector(Ctx, "setObject", "atIndexedSubscript");
+      ArrayByAddingObjectSel = getKeywordSelector(Ctx, "arrayByAddingObject");
+    }
+
+    if (S == ArrayWithObjectSel || S == AddObjectSel ||
+        S == InsertObjectAtIndexSel || S == ArrayByAddingObjectSel) {
+      Arg = 0;
+    } else if (S == SetObjectAtIndexedSubscriptSel) {
+      Arg = 0;
+      CanBeSubscript = true;
+    } else if (S == ReplaceObjectAtIndexWithObjectSel) {
+      Arg = 1;
+    }
+  } else if (Class == FC_NSDictionary) {
+    Selector S = msg.getSelector();
+
+    if (S.isUnarySelector())
+      return;
+
+    if (DictionaryWithObjectForKeySel.isNull()) {
+      ASTContext &Ctx = C.getASTContext();
+      DictionaryWithObjectForKeySel =
+          getKeywordSelector(Ctx, "dictionaryWithObject", "forKey");
+      SetObjectForKeySel = getKeywordSelector(Ctx, "setObject", "forKey");
+      SetObjectForKeyedSubscriptSel =
+          getKeywordSelector(Ctx, "setObject", "forKeyedSubscript");
+      RemoveObjectForKeySel = getKeywordSelector(Ctx, "removeObjectForKey");
+    }
+
+    if (S == DictionaryWithObjectForKeySel || S == SetObjectForKeySel) {
+      Arg = 0;
+      warnIfNilArg(C, msg, /* Arg */1, Class);
+    } else if (S == SetObjectForKeyedSubscriptSel) {
+      CanBeSubscript = true;
+      Arg = 1;
+    } else if (S == RemoveObjectForKeySel) {
+      Arg = 0;
+    }
+  }
+
+  // If argument is '0', report a warning.
+  if ((Arg != InvalidArgIndex))
+    warnIfNilArg(C, msg, Arg, Class, CanBeSubscript);
+}
+
+void NilArgChecker::checkPostStmt(const ObjCArrayLiteral *AL,
+                                  CheckerContext &C) const {
+  unsigned NumOfElements = AL->getNumElements();
+  for (unsigned i = 0; i < NumOfElements; ++i) {
+    warnIfNilExpr(AL->getElement(i), "Array element cannot be nil", C);
+  }
+}
+
+void NilArgChecker::checkPostStmt(const ObjCDictionaryLiteral *DL,
+                                  CheckerContext &C) const {
+  unsigned NumOfElements = DL->getNumElements();
+  for (unsigned i = 0; i < NumOfElements; ++i) {
+    ObjCDictionaryElement Element = DL->getKeyValueElement(i);
+    warnIfNilExpr(Element.Key, "Dictionary key cannot be nil", C);
+    warnIfNilExpr(Element.Value, "Dictionary value cannot be nil", C);
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Checking for mismatched types passed to CFNumberCreate/CFNumberGetValue.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class CFNumberChecker : public Checker< check::PreStmt<CallExpr> > {
+  mutable std::unique_ptr<APIMisuse> BT;
+  mutable IdentifierInfo *ICreate, *IGetValue;
+public:
+  CFNumberChecker() : ICreate(nullptr), IGetValue(nullptr) {}
+
+  void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
+};
+} // end anonymous namespace
+
+enum CFNumberType {
+  kCFNumberSInt8Type = 1,
+  kCFNumberSInt16Type = 2,
+  kCFNumberSInt32Type = 3,
+  kCFNumberSInt64Type = 4,
+  kCFNumberFloat32Type = 5,
+  kCFNumberFloat64Type = 6,
+  kCFNumberCharType = 7,
+  kCFNumberShortType = 8,
+  kCFNumberIntType = 9,
+  kCFNumberLongType = 10,
+  kCFNumberLongLongType = 11,
+  kCFNumberFloatType = 12,
+  kCFNumberDoubleType = 13,
+  kCFNumberCFIndexType = 14,
+  kCFNumberNSIntegerType = 15,
+  kCFNumberCGFloatType = 16
+};
+
+static std::optional<uint64_t> GetCFNumberSize(ASTContext &Ctx, uint64_t i) {
+  static const unsigned char FixedSize[] = { 8, 16, 32, 64, 32, 64 };
+
+  if (i < kCFNumberCharType)
+    return FixedSize[i-1];
+
+  QualType T;
+
+  switch (i) {
+    case kCFNumberCharType:     T = Ctx.CharTy;     break;
+    case kCFNumberShortType:    T = Ctx.ShortTy;    break;
+    case kCFNumberIntType:      T = Ctx.IntTy;      break;
+    case kCFNumberLongType:     T = Ctx.LongTy;     break;
+    case kCFNumberLongLongType: T = Ctx.LongLongTy; break;
+    case kCFNumberFloatType:    T = Ctx.FloatTy;    break;
+    case kCFNumberDoubleType:   T = Ctx.DoubleTy;   break;
+    case kCFNumberCFIndexType:
+    case kCFNumberNSIntegerType:
+    case kCFNumberCGFloatType:
+      // FIXME: We need a way to map from names to Type*.
+    default:
+      return std::nullopt;
+  }
+
+  return Ctx.getTypeSize(T);
+}
+
+#if 0
+static const char* GetCFNumberTypeStr(uint64_t i) {
+  static const char* Names[] = {
+    "kCFNumberSInt8Type",
+    "kCFNumberSInt16Type",
+    "kCFNumberSInt32Type",
+    "kCFNumberSInt64Type",
+    "kCFNumberFloat32Type",
+    "kCFNumberFloat64Type",
+    "kCFNumberCharType",
+    "kCFNumberShortType",
+    "kCFNumberIntType",
+    "kCFNumberLongType",
+    "kCFNumberLongLongType",
+    "kCFNumberFloatType",
+    "kCFNumberDoubleType",
+    "kCFNumberCFIndexType",
+    "kCFNumberNSIntegerType",
+    "kCFNumberCGFloatType"
+  };
+
+  return i <= kCFNumberCGFloatType ? Names[i-1] : "Invalid CFNumberType";
+}
+#endif
+
+void CFNumberChecker::checkPreStmt(const CallExpr *CE,
+                                         CheckerContext &C) const {
+  ProgramStateRef state = C.getState();
+  const FunctionDecl *FD = C.getCalleeDecl(CE);
+  if (!FD)
+    return;
+
+  ASTContext &Ctx = C.getASTContext();
+  if (!ICreate) {
+    ICreate = &Ctx.Idents.get("CFNumberCreate");
+    IGetValue = &Ctx.Idents.get("CFNumberGetValue");
+  }
+  if (!(FD->getIdentifier() == ICreate || FD->getIdentifier() == IGetValue) ||
+      CE->getNumArgs() != 3)
+    return;
+
+  // Get the value of the "theType" argument.
+  SVal TheTypeVal = C.getSVal(CE->getArg(1));
+
+  // FIXME: We really should allow ranges of valid theType values, and
+  //   bifurcate the state appropriately.
+  std::optional<nonloc::ConcreteInt> V =
+      dyn_cast<nonloc::ConcreteInt>(TheTypeVal);
+  if (!V)
+    return;
+
+  uint64_t NumberKind = V->getValue().getLimitedValue();
+  std::optional<uint64_t> OptCFNumberSize = GetCFNumberSize(Ctx, NumberKind);
+
+  // FIXME: In some cases we can emit an error.
+  if (!OptCFNumberSize)
+    return;
+
+  uint64_t CFNumberSize = *OptCFNumberSize;
+
+  // Look at the value of the integer being passed by reference.  Essentially
+  // we want to catch cases where the value passed in is not equal to the
+  // size of the type being created.
+  SVal TheValueExpr = C.getSVal(CE->getArg(2));
+
+  // FIXME: Eventually we should handle arbitrary locations.  We can do this
+  //  by having an enhanced memory model that does low-level typing.
+  std::optional<loc::MemRegionVal> LV = TheValueExpr.getAs<loc::MemRegionVal>();
+  if (!LV)
+    return;
+
+  const TypedValueRegion* R = dyn_cast<TypedValueRegion>(LV->stripCasts());
+  if (!R)
+    return;
+
+  QualType T = Ctx.getCanonicalType(R->getValueType());
+
+  // FIXME: If the pointee isn't an integer type, should we flag a warning?
+  //  People can do weird stuff with pointers.
+
+  if (!T->isIntegralOrEnumerationType())
+    return;
+
+  uint64_t PrimitiveTypeSize = Ctx.getTypeSize(T);
+
+  if (PrimitiveTypeSize == CFNumberSize)
+    return;
+
+  // FIXME: We can actually create an abstract "CFNumber" object that has
+  //  the bits initialized to the provided values.
+  ExplodedNode *N = C.generateNonFatalErrorNode();
+  if (N) {
+    SmallString<128> sbuf;
+    llvm::raw_svector_ostream os(sbuf);
+    bool isCreate = (FD->getIdentifier() == ICreate);
+
+    if (isCreate) {
+      os << (PrimitiveTypeSize == 8 ? "An " : "A ")
+         << PrimitiveTypeSize << "-bit integer is used to initialize a "
+         << "CFNumber object that represents "
+         << (CFNumberSize == 8 ? "an " : "a ")
+         << CFNumberSize << "-bit integer; ";
+    } else {
+      os << "A CFNumber object that represents "
+         << (CFNumberSize == 8 ? "an " : "a ")
+         << CFNumberSize << "-bit integer is used to initialize "
+         << (PrimitiveTypeSize == 8 ? "an " : "a ")
+         << PrimitiveTypeSize << "-bit integer; ";
+    }
+
+    if (PrimitiveTypeSize < CFNumberSize)
+      os << (CFNumberSize - PrimitiveTypeSize)
+      << " bits of the CFNumber value will "
+      << (isCreate ? "be garbage." : "overwrite adjacent storage.");
+    else
+      os << (PrimitiveTypeSize - CFNumberSize)
+      << " bits of the integer value will be "
+      << (isCreate ? "lost." : "garbage.");
+
+    if (!BT)
+      BT.reset(new APIMisuse(this, "Bad use of CFNumber APIs"));
+
+    auto report = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N);
+    report->addRange(CE->getArg(2)->getSourceRange());
+    C.emitReport(std::move(report));
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// CFRetain/CFRelease/CFMakeCollectable/CFAutorelease checking for null arguments.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class CFRetainReleaseChecker : public Checker<check::PreCall> {
+  mutable APIMisuse BT{this, "null passed to CF memory management function"};
+  const CallDescriptionSet ModelledCalls = {
+      {{"CFRetain"}, 1},
+      {{"CFRelease"}, 1},
+      {{"CFMakeCollectable"}, 1},
+      {{"CFAutorelease"}, 1},
+  };
+
+public:
+  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
+};
+} // end anonymous namespace
+
+void CFRetainReleaseChecker::checkPreCall(const CallEvent &Call,
+                                          CheckerContext &C) const {
+  // TODO: Make this check part of CallDescription.
+  if (!Call.isGlobalCFunction())
+    return;
+
+  // Check if we called CFRetain/CFRelease/CFMakeCollectable/CFAutorelease.
+  if (!ModelledCalls.contains(Call))
+    return;
+
+  // Get the argument's value.
+  SVal ArgVal = Call.getArgSVal(0);
+  std::optional<DefinedSVal> DefArgVal = ArgVal.getAs<DefinedSVal>();
+  if (!DefArgVal)
+    return;
+
+  // Is it null?
+  ProgramStateRef state = C.getState();
+  ProgramStateRef stateNonNull, stateNull;
+  std::tie(stateNonNull, stateNull) = state->assume(*DefArgVal);
+
+  if (!stateNonNull) {
+    ExplodedNode *N = C.generateErrorNode(stateNull);
+    if (!N)
+      return;
+
+    SmallString<64> Str;
+    raw_svector_ostream OS(Str);
+    OS << "Null pointer argument in call to "
+       << cast<FunctionDecl>(Call.getDecl())->getName();
+
+    auto report = std::make_unique<PathSensitiveBugReport>(BT, OS.str(), N);
+    report->addRange(Call.getArgSourceRange(0));
+    bugreporter::trackExpressionValue(N, Call.getArgExpr(0), *report);
+    C.emitReport(std::move(report));
+    return;
+  }
+
+  // From here on, we know the argument is non-null.
+  C.addTransition(stateNonNull);
+}
+
+//===----------------------------------------------------------------------===//
+// Check for sending 'retain', 'release', or 'autorelease' directly to a Class.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class ClassReleaseChecker : public Checker<check::PreObjCMessage> {
+  mutable Selector releaseS;
+  mutable Selector retainS;
+  mutable Selector autoreleaseS;
+  mutable Selector drainS;
+  mutable std::unique_ptr<BugType> BT;
+
+public:
+  void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
+};
+} // end anonymous namespace
+
+void ClassReleaseChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
+                                              CheckerContext &C) const {
+  if (!BT) {
+    BT.reset(new APIMisuse(
+        this, "message incorrectly sent to class instead of class instance"));
+
+    ASTContext &Ctx = C.getASTContext();
+    releaseS = GetNullarySelector("release", Ctx);
+    retainS = GetNullarySelector("retain", Ctx);
+    autoreleaseS = GetNullarySelector("autorelease", Ctx);
+    drainS = GetNullarySelector("drain", Ctx);
+  }
+
+  if (msg.isInstanceMessage())
+    return;
+  const ObjCInterfaceDecl *Class = msg.getReceiverInterface();
+  assert(Class);
+
+  Selector S = msg.getSelector();
+  if (!(S == releaseS || S == retainS || S == autoreleaseS || S == drainS))
+    return;
+
+  if (ExplodedNode *N = C.generateNonFatalErrorNode()) {
+    SmallString<200> buf;
+    llvm::raw_svector_ostream os(buf);
+
+    os << "The '";
+    S.print(os);
+    os << "' message should be sent to instances "
+          "of class '" << Class->getName()
+       << "' and not the class directly";
+
+    auto report = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N);
+    report->addRange(msg.getSourceRange());
+    C.emitReport(std::move(report));
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Check for passing non-Objective-C types to variadic methods that expect
+// only Objective-C types.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class VariadicMethodTypeChecker : public Checker<check::PreObjCMessage> {
+  mutable Selector arrayWithObjectsS;
+  mutable Selector dictionaryWithObjectsAndKeysS;
+  mutable Selector setWithObjectsS;
+  mutable Selector orderedSetWithObjectsS;
+  mutable Selector initWithObjectsS;
+  mutable Selector initWithObjectsAndKeysS;
+  mutable std::unique_ptr<BugType> BT;
+
+  bool isVariadicMessage(const ObjCMethodCall &msg) const;
+
+public:
+  void checkPreObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
+};
+} // end anonymous namespace
+
+/// isVariadicMessage - Returns whether the given message is a variadic message,
+/// where all arguments must be Objective-C types.
+bool
+VariadicMethodTypeChecker::isVariadicMessage(const ObjCMethodCall &msg) const {
+  const ObjCMethodDecl *MD = msg.getDecl();
+
+  if (!MD || !MD->isVariadic() || isa<ObjCProtocolDecl>(MD->getDeclContext()))
+    return false;
+
+  Selector S = msg.getSelector();
+
+  if (msg.isInstanceMessage()) {
+    // FIXME: Ideally we'd look at the receiver interface here, but that's not
+    // useful for init, because alloc returns 'id'. In theory, this could lead
+    // to false positives, for example if there existed a class that had an
+    // initWithObjects: implementation that does accept non-Objective-C pointer
+    // types, but the chance of that happening is pretty small compared to the
+    // gains that this analysis gives.
+    const ObjCInterfaceDecl *Class = MD->getClassInterface();
+
+    switch (findKnownClass(Class)) {
+    case FC_NSArray:
+    case FC_NSOrderedSet:
+    case FC_NSSet:
+      return S == initWithObjectsS;
+    case FC_NSDictionary:
+      return S == initWithObjectsAndKeysS;
+    default:
+      return false;
+    }
+  } else {
+    const ObjCInterfaceDecl *Class = msg.getReceiverInterface();
+
+    switch (findKnownClass(Class)) {
+      case FC_NSArray:
+        return S == arrayWithObjectsS;
+      case FC_NSOrderedSet:
+        return S == orderedSetWithObjectsS;
+      case FC_NSSet:
+        return S == setWithObjectsS;
+      case FC_NSDictionary:
+        return S == dictionaryWithObjectsAndKeysS;
+      default:
+        return false;
+    }
+  }
+}
+
+void VariadicMethodTypeChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
+                                                    CheckerContext &C) const {
+  if (!BT) {
+    BT.reset(new APIMisuse(this,
+                           "Arguments passed to variadic method aren't all "
+                           "Objective-C pointer types"));
+
+    ASTContext &Ctx = C.getASTContext();
+    arrayWithObjectsS = GetUnarySelector("arrayWithObjects", Ctx);
+    dictionaryWithObjectsAndKeysS =
+      GetUnarySelector("dictionaryWithObjectsAndKeys", Ctx);
+    setWithObjectsS = GetUnarySelector("setWithObjects", Ctx);
+    orderedSetWithObjectsS = GetUnarySelector("orderedSetWithObjects", Ctx);
+
+    initWithObjectsS = GetUnarySelector("initWithObjects", Ctx);
+    initWithObjectsAndKeysS = GetUnarySelector("initWithObjectsAndKeys", Ctx);
+  }
+
+  if (!isVariadicMessage(msg))
+      return;
+
+  // We are not interested in the selector arguments since they have
+  // well-defined types, so the compiler will issue a warning for them.
+  unsigned variadicArgsBegin = msg.getSelector().getNumArgs();
+
+  // We're not interested in the last argument since it has to be nil or the
+  // compiler would have issued a warning for it elsewhere.
+  unsigned variadicArgsEnd = msg.getNumArgs() - 1;
+
+  if (variadicArgsEnd <= variadicArgsBegin)
+    return;
+
+  // Verify that all arguments have Objective-C types.
+  std::optional<ExplodedNode *> errorNode;
+
+  for (unsigned I = variadicArgsBegin; I != variadicArgsEnd; ++I) {
+    QualType ArgTy = msg.getArgExpr(I)->getType();
+    if (ArgTy->isObjCObjectPointerType())
+      continue;
+
+    // Block pointers are treaded as Objective-C pointers.
+    if (ArgTy->isBlockPointerType())
+      continue;
+
+    // Ignore pointer constants.
+    if (isa<loc::ConcreteInt>(msg.getArgSVal(I)))
+      continue;
+
+    // Ignore pointer types annotated with 'NSObject' attribute.
+    if (C.getASTContext().isObjCNSObjectType(ArgTy))
+      continue;
+
+    // Ignore CF references, which can be toll-free bridged.
+    if (coreFoundation::isCFObjectRef(ArgTy))
+      continue;
+
+    // Generate only one error node to use for all bug reports.
+    if (!errorNode)
+      errorNode = C.generateNonFatalErrorNode();
+
+    if (!*errorNode)
+      continue;
+
+    SmallString<128> sbuf;
+    llvm::raw_svector_ostream os(sbuf);
+
+    StringRef TypeName = GetReceiverInterfaceName(msg);
+    if (!TypeName.empty())
+      os << "Argument to '" << TypeName << "' method '";
+    else
+      os << "Argument to method '";
+
+    msg.getSelector().print(os);
+    os << "' should be an Objective-C pointer type, not '";
+    ArgTy.print(os, C.getLangOpts());
+    os << "'";
+
+    auto R =
+        std::make_unique<PathSensitiveBugReport>(*BT, os.str(), *errorNode);
+    R->addRange(msg.getArgSourceRange(I));
+    C.emitReport(std::move(R));
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Improves the modeling of loops over Cocoa collections.
+//===----------------------------------------------------------------------===//
+
+// The map from container symbol to the container count symbol.
+// We currently will remember the last container count symbol encountered.
+REGISTER_MAP_WITH_PROGRAMSTATE(ContainerCountMap, SymbolRef, SymbolRef)
+REGISTER_MAP_WITH_PROGRAMSTATE(ContainerNonEmptyMap, SymbolRef, bool)
+
+namespace {
+class ObjCLoopChecker
+  : public Checker<check::PostStmt<ObjCForCollectionStmt>,
+                   check::PostObjCMessage,
+                   check::DeadSymbols,
+                   check::PointerEscape > {
+  mutable IdentifierInfo *CountSelectorII;
+
+  bool isCollectionCountMethod(const ObjCMethodCall &M,
+                               CheckerContext &C) const;
+
+public:
+  ObjCLoopChecker() : CountSelectorII(nullptr) {}
+  void checkPostStmt(const ObjCForCollectionStmt *FCS, CheckerContext &C) const;
+  void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
+  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
+  ProgramStateRef checkPointerEscape(ProgramStateRef State,
+                                     const InvalidatedSymbols &Escaped,
+                                     const CallEvent *Call,
+                                     PointerEscapeKind Kind) const;
+};
+} // end anonymous namespace
+
+static bool isKnownNonNilCollectionType(QualType T) {
+  const ObjCObjectPointerType *PT = T->getAs<ObjCObjectPointerType>();
+  if (!PT)
+    return false;
+
+  const ObjCInterfaceDecl *ID = PT->getInterfaceDecl();
+  if (!ID)
+    return false;
+
+  switch (findKnownClass(ID)) {
+  case FC_NSArray:
+  case FC_NSDictionary:
+  case FC_NSEnumerator:
+  case FC_NSOrderedSet:
+  case FC_NSSet:
+    return true;
+  default:
+    return false;
+  }
+}
+
+/// Assumes that the collection is non-nil.
+///
+/// If the collection is known to be nil, returns NULL to indicate an infeasible
+/// path.
+static ProgramStateRef checkCollectionNonNil(CheckerContext &C,
+                                             ProgramStateRef State,
+                                             const ObjCForCollectionStmt *FCS) {
+  if (!State)
+    return nullptr;
+
+  SVal CollectionVal = C.getSVal(FCS->getCollection());
+  std::optional<DefinedSVal> KnownCollection =
+      CollectionVal.getAs<DefinedSVal>();
+  if (!KnownCollection)
+    return State;
+
+  ProgramStateRef StNonNil, StNil;
+  std::tie(StNonNil, StNil) = State->assume(*KnownCollection);
+  if (StNil && !StNonNil) {
+    // The collection is nil. This path is infeasible.
+    return nullptr;
+  }
+
+  return StNonNil;
+}
+
+/// Assumes that the collection elements are non-nil.
+///
+/// This only applies if the collection is one of those known not to contain
+/// nil values.
+static ProgramStateRef checkElementNonNil(CheckerContext &C,
+                                          ProgramStateRef State,
+                                          const ObjCForCollectionStmt *FCS) {
+  if (!State)
+    return nullptr;
+
+  // See if the collection is one where we /know/ the elements are non-nil.
+  if (!isKnownNonNilCollectionType(FCS->getCollection()->getType()))
+    return State;
+
+  const LocationContext *LCtx = C.getLocationContext();
+  const Stmt *Element = FCS->getElement();
+
+  // FIXME: Copied from ExprEngineObjC.
+  std::optional<Loc> ElementLoc;
+  if (const DeclStmt *DS = dyn_cast<DeclStmt>(Element)) {
+    const VarDecl *ElemDecl = cast<VarDecl>(DS->getSingleDecl());
+    assert(ElemDecl->getInit() == nullptr);
+    ElementLoc = State->getLValue(ElemDecl, LCtx);
+  } else {
+    ElementLoc = State->getSVal(Element, LCtx).getAs<Loc>();
+  }
+
+  if (!ElementLoc)
+    return State;
+
+  // Go ahead and assume the value is non-nil.
+  SVal Val = State->getSVal(*ElementLoc);
+  return State->assume(cast<DefinedOrUnknownSVal>(Val), true);
+}
+
+/// Returns NULL state if the collection is known to contain elements
+/// (or is known not to contain elements if the Assumption parameter is false.)
+static ProgramStateRef
+assumeCollectionNonEmpty(CheckerContext &C, ProgramStateRef State,
+                         SymbolRef CollectionS, bool Assumption) {
+  if (!State || !CollectionS)
+    return State;
+
+  const SymbolRef *CountS = State->get<ContainerCountMap>(CollectionS);
+  if (!CountS) {
+    const bool *KnownNonEmpty = State->get<ContainerNonEmptyMap>(CollectionS);
+    if (!KnownNonEmpty)
+      return State->set<ContainerNonEmptyMap>(CollectionS, Assumption);
+    return (Assumption == *KnownNonEmpty) ? State : nullptr;
+  }
+
+  SValBuilder &SvalBuilder = C.getSValBuilder();
+  SVal CountGreaterThanZeroVal =
+    SvalBuilder.evalBinOp(State, BO_GT,
+                          nonloc::SymbolVal(*CountS),
+                          SvalBuilder.makeIntVal(0, (*CountS)->getType()),
+                          SvalBuilder.getConditionType());
+  std::optional<DefinedSVal> CountGreaterThanZero =
+      CountGreaterThanZeroVal.getAs<DefinedSVal>();
+  if (!CountGreaterThanZero) {
+    // The SValBuilder cannot construct a valid SVal for this condition.
+    // This means we cannot properly reason about it.
+    return State;
+  }
+
+  return State->assume(*CountGreaterThanZero, Assumption);
+}
+
+static ProgramStateRef
+assumeCollectionNonEmpty(CheckerContext &C, ProgramStateRef State,
+                         const ObjCForCollectionStmt *FCS,
+                         bool Assumption) {
+  if (!State)
+    return nullptr;
+
+  SymbolRef CollectionS = C.getSVal(FCS->getCollection()).getAsSymbol();
+  return assumeCollectionNonEmpty(C, State, CollectionS, Assumption);
+}
+
+/// If the fist block edge is a back edge, we are reentering the loop.
+static bool alreadyExecutedAtLeastOneLoopIteration(const ExplodedNode *N,
+                                             const ObjCForCollectionStmt *FCS) {
+  if (!N)
+    return false;
+
+  ProgramPoint P = N->getLocation();
+  if (std::optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
+    return BE->getSrc()->getLoopTarget() == FCS;
+  }
+
+  // Keep looking for a block edge.
+  for (ExplodedNode::const_pred_iterator I = N->pred_begin(),
+                                         E = N->pred_end(); I != E; ++I) {
+    if (alreadyExecutedAtLeastOneLoopIteration(*I, FCS))
+      return true;
+  }
+
+  return false;
+}
+
+void ObjCLoopChecker::checkPostStmt(const ObjCForCollectionStmt *FCS,
+                                    CheckerContext &C) const {
+  ProgramStateRef State = C.getState();
+
+  // Check if this is the branch for the end of the loop.
+  if (!ExprEngine::hasMoreIteration(State, FCS, C.getLocationContext())) {
+    if (!alreadyExecutedAtLeastOneLoopIteration(C.getPredecessor(), FCS))
+      State = assumeCollectionNonEmpty(C, State, FCS, /*Assumption*/false);
+
+  // Otherwise, this is a branch that goes through the loop body.
+  } else {
+    State = checkCollectionNonNil(C, State, FCS);
+    State = checkElementNonNil(C, State, FCS);
+    State = assumeCollectionNonEmpty(C, State, FCS, /*Assumption*/true);
+  }
+
+  if (!State)
+    C.generateSink(C.getState(), C.getPredecessor());
+  else if (State != C.getState())
+    C.addTransition(State);
+}
+
+bool ObjCLoopChecker::isCollectionCountMethod(const ObjCMethodCall &M,
+                                              CheckerContext &C) const {
+  Selector S = M.getSelector();
+  // Initialize the identifiers on first use.
+  if (!CountSelectorII)
+    CountSelectorII = &C.getASTContext().Idents.get("count");
+
+  // If the method returns collection count, record the value.
+  return S.isUnarySelector() &&
+         (S.getIdentifierInfoForSlot(0) == CountSelectorII);
+}
+
+void ObjCLoopChecker::checkPostObjCMessage(const ObjCMethodCall &M,
+                                           CheckerContext &C) const {
+  if (!M.isInstanceMessage())
+    return;
+
+  const ObjCInterfaceDecl *ClassID = M.getReceiverInterface();
+  if (!ClassID)
+    return;
+
+  FoundationClass Class = findKnownClass(ClassID);
+  if (Class != FC_NSDictionary &&
+      Class != FC_NSArray &&
+      Class != FC_NSSet &&
+      Class != FC_NSOrderedSet)
+    return;
+
+  SymbolRef ContainerS = M.getReceiverSVal().getAsSymbol();
+  if (!ContainerS)
+    return;
+
+  // If we are processing a call to "count", get the symbolic value returned by
+  // a call to "count" and add it to the map.
+  if (!isCollectionCountMethod(M, C))
+    return;
+
+  const Expr *MsgExpr = M.getOriginExpr();
+  SymbolRef CountS = C.getSVal(MsgExpr).getAsSymbol();
+  if (CountS) {
+    ProgramStateRef State = C.getState();
+
+    C.getSymbolManager().addSymbolDependency(ContainerS, CountS);
+    State = State->set<ContainerCountMap>(ContainerS, CountS);
+
+    if (const bool *NonEmpty = State->get<ContainerNonEmptyMap>(ContainerS)) {
+      State = State->remove<ContainerNonEmptyMap>(ContainerS);
+      State = assumeCollectionNonEmpty(C, State, ContainerS, *NonEmpty);
+    }
+
+    C.addTransition(State);
+  }
+}
+
+static SymbolRef getMethodReceiverIfKnownImmutable(const CallEvent *Call) {
+  const ObjCMethodCall *Message = dyn_cast_or_null<ObjCMethodCall>(Call);
+  if (!Message)
+    return nullptr;
+
+  const ObjCMethodDecl *MD = Message->getDecl();
+  if (!MD)
+    return nullptr;
+
+  const ObjCInterfaceDecl *StaticClass;
+  if (isa<ObjCProtocolDecl>(MD->getDeclContext())) {
+    // We can't find out where the method was declared without doing more work.
+    // Instead, see if the receiver is statically typed as a known immutable
+    // collection.
+    StaticClass = Message->getOriginExpr()->getReceiverInterface();
+  } else {
+    StaticClass = MD->getClassInterface();
+  }
+
+  if (!StaticClass)
+    return nullptr;
+
+  switch (findKnownClass(StaticClass, /*IncludeSuper=*/false)) {
+  case FC_None:
+    return nullptr;
+  case FC_NSArray:
+  case FC_NSDictionary:
+  case FC_NSEnumerator:
+  case FC_NSNull:
+  case FC_NSOrderedSet:
+  case FC_NSSet:
+  case FC_NSString:
+    break;
+  }
+
+  return Message->getReceiverSVal().getAsSymbol();
+}
+
+ProgramStateRef
+ObjCLoopChecker::checkPointerEscape(ProgramStateRef State,
+                                    const InvalidatedSymbols &Escaped,
+                                    const CallEvent *Call,
+                                    PointerEscapeKind Kind) const {
+  SymbolRef ImmutableReceiver = getMethodReceiverIfKnownImmutable(Call);
+
+  // Remove the invalidated symbols from the collection count map.
+  for (InvalidatedSymbols::const_iterator I = Escaped.begin(),
+       E = Escaped.end();
+       I != E; ++I) {
+    SymbolRef Sym = *I;
+
+    // Don't invalidate this symbol's count if we know the method being called
+    // is declared on an immutable class. This isn't completely correct if the
+    // receiver is also passed as an argument, but in most uses of NSArray,
+    // NSDictionary, etc. this isn't likely to happen in a dangerous way.
+    if (Sym == ImmutableReceiver)
+      continue;
+
+    // The symbol escaped. Pessimistically, assume that the count could have
+    // changed.
+    State = State->remove<ContainerCountMap>(Sym);
+    State = State->remove<ContainerNonEmptyMap>(Sym);
+  }
+  return State;
+}
+
+void ObjCLoopChecker::checkDeadSymbols(SymbolReaper &SymReaper,
+                                       CheckerContext &C) const {
+  ProgramStateRef State = C.getState();
+
+  // Remove the dead symbols from the collection count map.
+  ContainerCountMapTy Tracked = State->get<ContainerCountMap>();
+  for (ContainerCountMapTy::iterator I = Tracked.begin(),
+                                     E = Tracked.end(); I != E; ++I) {
+    SymbolRef Sym = I->first;
+    if (SymReaper.isDead(Sym)) {
+      State = State->remove<ContainerCountMap>(Sym);
+      State = State->remove<ContainerNonEmptyMap>(Sym);
+    }
+  }
+
+  C.addTransition(State);
+}
+
+namespace {
+/// \class ObjCNonNilReturnValueChecker
+/// The checker restricts the return values of APIs known to
+/// never (or almost never) return 'nil'.
+class ObjCNonNilReturnValueChecker
+  : public Checker<check::PostObjCMessage,
+                   check::PostStmt<ObjCArrayLiteral>,
+                   check::PostStmt<ObjCDictionaryLiteral>,
+                   check::PostStmt<ObjCBoxedExpr> > {
+    mutable bool Initialized;
+    mutable Selector ObjectAtIndex;
+    mutable Selector ObjectAtIndexedSubscript;
+    mutable Selector NullSelector;
+
+public:
+  ObjCNonNilReturnValueChecker() : Initialized(false) {}
+
+  ProgramStateRef assumeExprIsNonNull(const Expr *NonNullExpr,
+                                      ProgramStateRef State,
+                                      CheckerContext &C) const;
+  void assumeExprIsNonNull(const Expr *E, CheckerContext &C) const {
+    C.addTransition(assumeExprIsNonNull(E, C.getState(), C));
+  }
+
+  void checkPostStmt(const ObjCArrayLiteral *E, CheckerContext &C) const {
+    assumeExprIsNonNull(E, C);
+  }
+  void checkPostStmt(const ObjCDictionaryLiteral *E, CheckerContext &C) const {
+    assumeExprIsNonNull(E, C);
+  }
+  void checkPostStmt(const ObjCBoxedExpr *E, CheckerContext &C) const {
+    assumeExprIsNonNull(E, C);
+  }
+
+  void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
+};
+} // end anonymous namespace
+
+ProgramStateRef
+ObjCNonNilReturnValueChecker::assumeExprIsNonNull(const Expr *NonNullExpr,
+                                                  ProgramStateRef State,
+                                                  CheckerContext &C) const {
+  SVal Val = C.getSVal(NonNullExpr);
+  if (std::optional<DefinedOrUnknownSVal> DV =
+          Val.getAs<DefinedOrUnknownSVal>())
+    return State->assume(*DV, true);
+  return State;
+}
+
+void ObjCNonNilReturnValueChecker::checkPostObjCMessage(const ObjCMethodCall &M,
+                                                        CheckerContext &C)
+                                                        const {
+  ProgramStateRef State = C.getState();
+
+  if (!Initialized) {
+    ASTContext &Ctx = C.getASTContext();
+    ObjectAtIndex = GetUnarySelector("objectAtIndex", Ctx);
+    ObjectAtIndexedSubscript = GetUnarySelector("objectAtIndexedSubscript", Ctx);
+    NullSelector = GetNullarySelector("null", Ctx);
+  }
+
+  // Check the receiver type.
+  if (const ObjCInterfaceDecl *Interface = M.getReceiverInterface()) {
+
+    // Assume that object returned from '[self init]' or '[super init]' is not
+    // 'nil' if we are processing an inlined function/method.
+    //
+    // A defensive callee will (and should) check if the object returned by
+    // '[super init]' is 'nil' before doing it's own initialization. However,
+    // since 'nil' is rarely returned in practice, we should not warn when the
+    // caller to the defensive constructor uses the object in contexts where
+    // 'nil' is not accepted.
+    if (!C.inTopFrame() && M.getDecl() &&
+        M.getDecl()->getMethodFamily() == OMF_init &&
+        M.isReceiverSelfOrSuper()) {
+      State = assumeExprIsNonNull(M.getOriginExpr(), State, C);
+    }
+
+    FoundationClass Cl = findKnownClass(Interface);
+
+    // Objects returned from
+    // [NSArray|NSOrderedSet]::[ObjectAtIndex|ObjectAtIndexedSubscript]
+    // are never 'nil'.
+    if (Cl == FC_NSArray || Cl == FC_NSOrderedSet) {
+      Selector Sel = M.getSelector();
+      if (Sel == ObjectAtIndex || Sel == ObjectAtIndexedSubscript) {
+        // Go ahead and assume the value is non-nil.
+        State = assumeExprIsNonNull(M.getOriginExpr(), State, C);
+      }
+    }
+
+    // Objects returned from [NSNull null] are not nil.
+    if (Cl == FC_NSNull) {
+      if (M.getSelector() == NullSelector) {
+        // Go ahead and assume the value is non-nil.
+        State = assumeExprIsNonNull(M.getOriginExpr(), State, C);
+      }
+    }
+  }
+  C.addTransition(State);
+}
+
+//===----------------------------------------------------------------------===//
+// Check registration.
+//===----------------------------------------------------------------------===//
+
+void ento::registerNilArgChecker(CheckerManager &mgr) {
+  mgr.registerChecker<NilArgChecker>();
+}
+
+bool ento::shouldRegisterNilArgChecker(const CheckerManager &mgr) {
+  return true;
+}
+
+void ento::registerCFNumberChecker(CheckerManager &mgr) {
+  mgr.registerChecker<CFNumberChecker>();
+}
+
+bool ento::shouldRegisterCFNumberChecker(const CheckerManager &mgr) {
+  return true;
+}
+
+void ento::registerCFRetainReleaseChecker(CheckerManager &mgr) {
+  mgr.registerChecker<CFRetainReleaseChecker>();
+}
+
+bool ento::shouldRegisterCFRetainReleaseChecker(const CheckerManager &mgr) {
+  return true;
+}
+
+void ento::registerClassReleaseChecker(CheckerManager &mgr) {
+  mgr.registerChecker<ClassReleaseChecker>();
+}
+
+bool ento::shouldRegisterClassReleaseChecker(const CheckerManager &mgr) {
+  return true;
+}
+
+void ento::registerVariadicMethodTypeChecker(CheckerManager &mgr) {
+  mgr.registerChecker<VariadicMethodTypeChecker>();
+}
+
+bool ento::shouldRegisterVariadicMethodTypeChecker(const CheckerManager &mgr) {
+  return true;
+}
+
+void ento::registerObjCLoopChecker(CheckerManager &mgr) {
+  mgr.registerChecker<ObjCLoopChecker>();
+}
+
+bool ento::shouldRegisterObjCLoopChecker(const CheckerManager &mgr) {
+  return true;
+}
+
+void ento::registerObjCNonNilReturnValueChecker(CheckerManager &mgr) {
+  mgr.registerChecker<ObjCNonNilReturnValueChecker>();
+}
+
+bool ento::shouldRegisterObjCNonNilReturnValueChecker(const CheckerManager &mgr) {
+  return true;
+}