C++ ASTContext::getCanonicalType方法代码示例

void CXXRecordDecl::addedAssignmentOperator(ASTContext &Context,
                                            CXXMethodDecl *OpDecl) {
  // We're interested specifically in copy assignment operators.
  // Unlike addedConstructor, this method is not called for implicit
  // declarations.
  const FunctionProtoType *FnType = OpDecl->getType()->getAsFunctionProtoType();
  assert(FnType && "Overloaded operator has no proto function type.");
  assert(FnType->getNumArgs() == 1 && !FnType->isVariadic());
  QualType ArgType = FnType->getArgType(0);
  if (const LValueReferenceType *Ref = ArgType->getAsLValueReferenceType())
    ArgType = Ref->getPointeeType();

  ArgType = ArgType.getUnqualifiedType();
  QualType ClassType = Context.getCanonicalType(Context.getTypeDeclType(
    const_cast<CXXRecordDecl*>(this)));

  if (ClassType != Context.getCanonicalType(ArgType))
    return;

  // This is a copy assignment operator.
  // Suppress the implicit declaration of a copy constructor.
  UserDeclaredCopyAssignment = true;

  // C++ [class]p4:
  //   A POD-struct is an aggregate class that [...] has no user-defined copy
  //   assignment operator [...].
  PlainOldData = false;
}

Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const {
  assert(!TR->isReferenceType() && "Expressions can't have reference type.");

  Cl::Kinds kind = ClassifyInternal(Ctx, this);
  // C99 6.3.2.1: An lvalue is an expression with an object type or an
  //   incomplete type other than void.
  if (!Ctx.getLangOptions().CPlusPlus) {
    // Thus, no functions.
    if (TR->isFunctionType() || TR == Ctx.OverloadTy)
      kind = Cl::CL_Function;
    // No void either, but qualified void is OK because it is "other than void".
    else if (TR->isVoidType() && !Ctx.getCanonicalType(TR).hasQualifiers())
      kind = Cl::CL_Void;
  }

  // Enable this assertion for testing.
  switch (kind) {
  case Cl::CL_LValue: assert(getValueKind() == VK_LValue); break;
  case Cl::CL_XValue: assert(getValueKind() == VK_XValue); break;
  case Cl::CL_Function:
  case Cl::CL_Void:
  case Cl::CL_DuplicateVectorComponents:
  case Cl::CL_MemberFunction:
  case Cl::CL_SubObjCPropertySetting:
  case Cl::CL_ClassTemporary:
  case Cl::CL_PRValue: assert(getValueKind() == VK_RValue); break;
  }

  Cl::ModifiableType modifiable = Cl::CM_Untested;
  if (Loc)
    modifiable = IsModifiable(Ctx, this, kind, *Loc);
  return Classification(kind, modifiable);
}

bool 
CXXConstructorDecl::isCopyConstructor(ASTContext &Context, 
                                      unsigned &TypeQuals) const {
  // C++ [class.copy]p2:
  //   A non-template constructor for class X is a copy constructor
  //   if its first parameter is of type X&, const X&, volatile X& or
  //   const volatile X&, and either there are no other parameters
  //   or else all other parameters have default arguments (8.3.6).
  if ((getNumParams() < 1) ||
      (getNumParams() > 1 && getParamDecl(1)->getDefaultArg() == 0))
    return false;

  const ParmVarDecl *Param = getParamDecl(0);

  // Do we have a reference type? Rvalue references don't count.
  const LValueReferenceType *ParamRefType =
    Param->getType()->getAsLValueReferenceType();
  if (!ParamRefType)
    return false;

  // Is it a reference to our class type?
  QualType PointeeType 
    = Context.getCanonicalType(ParamRefType->getPointeeType());
  QualType ClassTy 
    = Context.getTagDeclType(const_cast<CXXRecordDecl*>(getParent()));
  if (PointeeType.getUnqualifiedType() != ClassTy)
    return false;

  // We have a copy constructor.
  TypeQuals = PointeeType.getCVRQualifiers();
  return true;
}

static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E,
                                       Cl::Kinds Kind, SourceLocation &Loc) {
  // As a general rule, we only care about lvalues. But there are some rvalues
  // for which we want to generate special results.
  if (Kind == Cl::CL_PRValue) {
    // For the sake of better diagnostics, we want to specifically recognize
    // use of the GCC cast-as-lvalue extension.
    if (const ExplicitCastExpr *CE =
          dyn_cast<ExplicitCastExpr>(E->IgnoreParens())) {
      if (CE->getSubExpr()->IgnoreParenImpCasts()->isLValue()) {
        Loc = CE->getExprLoc();
        return Cl::CM_LValueCast;
      }
    }
  }
  if (Kind != Cl::CL_LValue)
    return Cl::CM_RValue;

  // This is the lvalue case.
  // Functions are lvalues in C++, but not modifiable. (C++ [basic.lval]p6)
  if (Ctx.getLangOpts().CPlusPlus && E->getType()->isFunctionType())
    return Cl::CM_Function;

  // Assignment to a property in ObjC is an implicit setter access. But a
  // setter might not exist.
  if (const ObjCPropertyRefExpr *Expr = dyn_cast<ObjCPropertyRefExpr>(E)) {
    if (Expr->isImplicitProperty() && Expr->getImplicitPropertySetter() == 0)
      return Cl::CM_NoSetterProperty;
  }

  CanQualType CT = Ctx.getCanonicalType(E->getType());
  // Const stuff is obviously not modifiable.
  if (CT.isConstQualified())
    return Cl::CM_ConstQualified;
  if (CT.getQualifiers().getAddressSpace() == LangAS::opencl_constant)
    return Cl::CM_ConstQualified;

  // Arrays are not modifiable, only their elements are.
  if (CT->isArrayType())
    return Cl::CM_ArrayType;
  // Incomplete types are not modifiable.
  if (CT->isIncompleteType())
    return Cl::CM_IncompleteType;

  // Records with any const fields (recursively) are not modifiable.
  if (const RecordType *R = CT->getAs<RecordType>()) {
    assert((E->getObjectKind() == OK_ObjCProperty ||
            !Ctx.getLangOpts().CPlusPlus) &&
           "C++ struct assignment should be resolved by the "
           "copy assignment operator.");
    if (R->hasConstFields())
      return Cl::CM_ConstQualified;
  }

  return Cl::CM_Modifiable;
}

static CanQualType GetConversionType(ASTContext &Context, NamedDecl *Conv) {
  QualType T;
  if (isa<UsingShadowDecl>(Conv))
    Conv = cast<UsingShadowDecl>(Conv)->getTargetDecl();
  if (FunctionTemplateDecl *ConvTemp = dyn_cast<FunctionTemplateDecl>(Conv))
    T = ConvTemp->getTemplatedDecl()->getResultType();
  else 
    T = cast<CXXConversionDecl>(Conv)->getConversionType();
  return Context.getCanonicalType(T);
}

bool CXXRecordDecl::hasConstCopyAssignment(ASTContext &Context) const {
  QualType ClassType = Context.getCanonicalType(Context.getTypeDeclType(
    const_cast<CXXRecordDecl*>(this)));
  DeclarationName OpName =Context.DeclarationNames.getCXXOperatorName(OO_Equal);

  DeclContext::lookup_const_iterator Op, OpEnd;
  for (llvm::tie(Op, OpEnd) = this->lookup(Context, OpName);
       Op != OpEnd; ++Op) {
    // C++ [class.copy]p9:
    //   A user-declared copy assignment operator is a non-static non-template
    //   member function of class X with exactly one parameter of type X, X&,
    //   const X&, volatile X& or const volatile X&.
    const CXXMethodDecl* Method = cast<CXXMethodDecl>(*Op);
    if (Method->isStatic())
      continue;
    // TODO: Skip templates? Or is this implicitly done due to parameter types?
    const FunctionProtoType *FnType =
      Method->getType()->getAsFunctionProtoType();
    assert(FnType && "Overloaded operator has no prototype.");
    // Don't assert on this; an invalid decl might have been left in the AST.
    if (FnType->getNumArgs() != 1 || FnType->isVariadic())
      continue;
    bool AcceptsConst = true;
    QualType ArgType = FnType->getArgType(0);
    if (const LValueReferenceType *Ref = ArgType->getAsLValueReferenceType()) {
      ArgType = Ref->getPointeeType();
      // Is it a non-const lvalue reference?
      if (!ArgType.isConstQualified())
        AcceptsConst = false;
    }
    if (Context.getCanonicalType(ArgType).getUnqualifiedType() != ClassType)
      continue;

    // We have a single argument of type cv X or cv X&, i.e. we've found the
    // copy assignment operator. Return whether it accepts const arguments.
    return AcceptsConst;
  }
  assert(isInvalidDecl() &&
         "No copy assignment operator declared in valid code.");
  return false;
}

bool CXXRecordDecl::hasConstCopyConstructor(ASTContext &Context) const {
  QualType ClassType
    = Context.getTypeDeclType(const_cast<CXXRecordDecl*>(this));
  DeclarationName ConstructorName 
    = Context.DeclarationNames.getCXXConstructorName(
                                           Context.getCanonicalType(ClassType));
  unsigned TypeQuals;
  DeclContext::lookup_const_iterator Con, ConEnd;
  for (llvm::tie(Con, ConEnd) = this->lookup(Context, ConstructorName);
       Con != ConEnd; ++Con) {
    if (cast<CXXConstructorDecl>(*Con)->isCopyConstructor(Context, TypeQuals) &&
        (TypeQuals & QualType::Const) != 0)
      return true;
  }

  return false;
}

Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const {
  assert(!TR->isReferenceType() && "Expressions can't have reference type.");

  Cl::Kinds kind = ClassifyInternal(Ctx, this);
  // C99 6.3.2.1: An lvalue is an expression with an object type or an
  //   incomplete type other than void.
  if (!Ctx.getLangOptions().CPlusPlus) {
    // Thus, no functions.
    if (TR->isFunctionType() || TR == Ctx.OverloadTy)
      kind = Cl::CL_Function;
    // No void either, but qualified void is OK because it is "other than void".
    else if (TR->isVoidType() && !Ctx.getCanonicalType(TR).hasQualifiers())
      kind = Cl::CL_Void;
  }

  Cl::ModifiableType modifiable = Cl::CM_Untested;
  if (Loc)
    modifiable = IsModifiable(Ctx, this, kind, *Loc);
  return Classification(kind, modifiable);
}

static bool isHigherOrderRawPtr(QualType T, ASTContext &C) {
    bool foundPointer = false;
    while (1) {
        const PointerType *PT = T->getAs<PointerType>();
        if (!PT) {
            if (!foundPointer)
                return false;

            // intptr_t* or intptr_t**, etc?
            if (T->isIntegerType() && C.getTypeSize(T) == C.getTypeSize(C.VoidPtrTy))
                return true;

            QualType X = C.getCanonicalType(T).getUnqualifiedType();
            return X == C.VoidTy;
        }

        foundPointer = true;
        T = PT->getPointeeType();
    }
}

void CXXRecordDecl::addedAssignmentOperator(ASTContext &Context,
                                            CXXMethodDecl *OpDecl) {
  // We're interested specifically in copy assignment operators.
  const FunctionProtoType *FnType = OpDecl->getType()->getAs<FunctionProtoType>();
  assert(FnType && "Overloaded operator has no proto function type.");
  assert(FnType->getNumArgs() == 1 && !FnType->isVariadic());
  
  // Copy assignment operators must be non-templates.
  if (OpDecl->getPrimaryTemplate() || OpDecl->getDescribedFunctionTemplate())
    return;
  
  QualType ArgType = FnType->getArgType(0);
  if (const LValueReferenceType *Ref = ArgType->getAs<LValueReferenceType>())
    ArgType = Ref->getPointeeType();

  ArgType = ArgType.getUnqualifiedType();
  QualType ClassType = Context.getCanonicalType(Context.getTypeDeclType(
    const_cast<CXXRecordDecl*>(this)));

  if (!Context.hasSameUnqualifiedType(ClassType, ArgType))
    return;

  // This is a copy assignment operator.
  // Note on the decl that it is a copy assignment operator.
  OpDecl->setCopyAssignment(true);

  // Suppress the implicit declaration of a copy constructor.
  data().UserDeclaredCopyAssignment = true;
  data().DeclaredCopyAssignment = true;
  
  // C++ [class.copy]p11:
  //   A copy assignment operator is trivial if it is implicitly declared.
  // FIXME: C++0x: don't do this for "= default" copy operators.
  data().HasTrivialCopyAssignment = false;

  // C++ [class]p4:
  //   A POD-struct is an aggregate class that [...] has no user-defined copy
  //   assignment operator [...].
  data().PlainOldData = false;
}

bool CXXBasePaths::lookupInBases(ASTContext &Context,
                                 const CXXRecordDecl *Record,
                               CXXRecordDecl::BaseMatchesCallback *BaseMatches, 
                                 void *UserData) {
  bool FoundPath = false;

  // The access of the path down to this record.
  AccessSpecifier AccessToHere = ScratchPath.Access;
  bool IsFirstStep = ScratchPath.empty();

  for (CXXRecordDecl::base_class_const_iterator BaseSpec = Record->bases_begin(),
         BaseSpecEnd = Record->bases_end(); 
       BaseSpec != BaseSpecEnd; 
       ++BaseSpec) {
    // Find the record of the base class subobjects for this type.
    QualType BaseType = Context.getCanonicalType(BaseSpec->getType())
                                                          .getUnqualifiedType();
    
    // C++ [temp.dep]p3:
    //   In the definition of a class template or a member of a class template,
    //   if a base class of the class template depends on a template-parameter,
    //   the base class scope is not examined during unqualified name lookup 
    //   either at the point of definition of the class template or member or 
    //   during an instantiation of the class tem- plate or member.
    if (BaseType->isDependentType())
      continue;
    
    // Determine whether we need to visit this base class at all,
    // updating the count of subobjects appropriately.
    std::pair<bool, unsigned>& Subobjects = ClassSubobjects[BaseType];
    bool VisitBase = true;
    bool SetVirtual = false;
    if (BaseSpec->isVirtual()) {
      VisitBase = !Subobjects.first;
      Subobjects.first = true;
      if (isDetectingVirtual() && DetectedVirtual == 0) {
        // If this is the first virtual we find, remember it. If it turns out
        // there is no base path here, we'll reset it later.
        DetectedVirtual = BaseType->getAs<RecordType>();
        SetVirtual = true;
      }
    } else
      ++Subobjects.second;
    
    if (isRecordingPaths()) {
      // Add this base specifier to the current path.
      CXXBasePathElement Element;
      Element.Base = &*BaseSpec;
      Element.Class = Record;
      if (BaseSpec->isVirtual())
        Element.SubobjectNumber = 0;
      else
        Element.SubobjectNumber = Subobjects.second;
      ScratchPath.push_back(Element);

      // Calculate the "top-down" access to this base class.
      // The spec actually describes this bottom-up, but top-down is
      // equivalent because the definition works out as follows:
      // 1. Write down the access along each step in the inheritance
      //    chain, followed by the access of the decl itself.
      //    For example, in
      //      class A { public: int foo; };
      //      class B : protected A {};
      //      class C : public B {};
      //      class D : private C {};
      //    we would write:
      //      private public protected public
      // 2. If 'private' appears anywhere except far-left, access is denied.
      // 3. Otherwise, overall access is determined by the most restrictive
      //    access in the sequence.
      if (IsFirstStep)
        ScratchPath.Access = BaseSpec->getAccessSpecifier();
      else
        ScratchPath.Access = CXXRecordDecl::MergeAccess(AccessToHere, 
                                                 BaseSpec->getAccessSpecifier());
    }
    
    // Track whether there's a path involving this specific base.
    bool FoundPathThroughBase = false;
    
    if (BaseMatches(BaseSpec, ScratchPath, UserData)) {
      // We've found a path that terminates at this base.
      FoundPath = FoundPathThroughBase = true;
      if (isRecordingPaths()) {
        // We have a path. Make a copy of it before moving on.
        Paths.push_back(ScratchPath);
      } else if (!isFindingAmbiguities()) {
        // We found a path and we don't care about ambiguities;
        // return immediately.
        return FoundPath;
      }
    } else if (VisitBase) {
      CXXRecordDecl *BaseRecord
        = cast<CXXRecordDecl>(BaseSpec->getType()->castAs<RecordType>()
                                ->getDecl());
      if (lookupInBases(Context, BaseRecord, BaseMatches, UserData)) {
        // C++ [class.member.lookup]p2:
        //   A member name f in one sub-object B hides a member name f in
        //   a sub-object A if A is a base class sub-object of B. Any
        //   declarations that are so hidden are eliminated from
//.........这里部分代码省略.........

clang::analyze_format_string::ArgType::MatchKind
ArgType::matchesType(ASTContext &C, QualType argTy) const {
  if (Ptr) {
    // It has to be a pointer.
    const PointerType *PT = argTy->getAs<PointerType>();
    if (!PT)
      return NoMatch;

    // We cannot write through a const qualified pointer.
    if (PT->getPointeeType().isConstQualified())
      return NoMatch;

    argTy = PT->getPointeeType();
  }

  switch (K) {
    case InvalidTy:
      llvm_unreachable("ArgType must be valid");

    case UnknownTy:
      return Match;

    case AnyCharTy: {
      if (const EnumType *ETy = argTy->getAs<EnumType>())
        argTy = ETy->getDecl()->getIntegerType();

      if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
        switch (BT->getKind()) {
          default:
            break;
          case BuiltinType::Char_S:
          case BuiltinType::SChar:
          case BuiltinType::UChar:
          case BuiltinType::Char_U:
            return Match;
        }
      return NoMatch;
    }

    case SpecificTy: {
      if (const EnumType *ETy = argTy->getAs<EnumType>())
        argTy = ETy->getDecl()->getIntegerType();
      argTy = C.getCanonicalType(argTy).getUnqualifiedType();

      if (T == argTy)
        return Match;
      // Check for "compatible types".
      if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
        switch (BT->getKind()) {
          default:
            break;
          case BuiltinType::Char_S:
          case BuiltinType::SChar:
          case BuiltinType::Char_U:
          case BuiltinType::UChar:
            return T == C.UnsignedCharTy || T == C.SignedCharTy ? Match
                                                                : NoMatch;
          case BuiltinType::Short:
            return T == C.UnsignedShortTy ? Match : NoMatch;
          case BuiltinType::UShort:
            return T == C.ShortTy ? Match : NoMatch;
          case BuiltinType::Int:
            return T == C.UnsignedIntTy ? Match : NoMatch;
          case BuiltinType::UInt:
            return T == C.IntTy ? Match : NoMatch;
          case BuiltinType::Long:
            return T == C.UnsignedLongTy ? Match : NoMatch;
          case BuiltinType::ULong:
            return T == C.LongTy ? Match : NoMatch;
          case BuiltinType::LongLong:
            return T == C.UnsignedLongLongTy ? Match : NoMatch;
          case BuiltinType::ULongLong:
            return T == C.LongLongTy ? Match : NoMatch;
        }
      return NoMatch;
    }

    case CStrTy: {
      const PointerType *PT = argTy->getAs<PointerType>();
      if (!PT)
        return NoMatch;
      QualType pointeeTy = PT->getPointeeType();
      if (const BuiltinType *BT = pointeeTy->getAs<BuiltinType>())
        switch (BT->getKind()) {
          case BuiltinType::Void:
          case BuiltinType::Char_U:
          case BuiltinType::UChar:
          case BuiltinType::Char_S:
          case BuiltinType::SChar:
            return Match;
          default:
            break;
        }

      return NoMatch;
    }

    case WCStrTy: {
      const PointerType *PT = argTy->getAs<PointerType>();
      if (!PT)
//.........这里部分代码省略.........

static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E,
                                       Cl::Kinds Kind, SourceLocation &Loc) {
  // As a general rule, we only care about lvalues. But there are some rvalues
  // for which we want to generate special results.
  if (Kind == Cl::CL_PRValue) {
    // For the sake of better diagnostics, we want to specifically recognize
    // use of the GCC cast-as-lvalue extension.
    if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E->IgnoreParens())){
      if (CE->getSubExpr()->Classify(Ctx).isLValue()) {
        Loc = CE->getLParenLoc();
        return Cl::CM_LValueCast;
      }
    }
  }
  if (Kind != Cl::CL_LValue)
    return Cl::CM_RValue;

  // This is the lvalue case.
  // Functions are lvalues in C++, but not modifiable. (C++ [basic.lval]p6)
  if (Ctx.getLangOptions().CPlusPlus && E->getType()->isFunctionType())
    return Cl::CM_Function;

  // You cannot assign to a variable outside a block from within the block if
  // it is not marked __block, e.g.
  //   void takeclosure(void (^C)(void));
  //   void func() { int x = 1; takeclosure(^{ x = 7; }); }
  if (const BlockDeclRefExpr *BDR = dyn_cast<BlockDeclRefExpr>(E)) {
    if (!BDR->isByRef() && isa<VarDecl>(BDR->getDecl()))
      return Cl::CM_NotBlockQualified;
  }

  // Assignment to a property in ObjC is an implicit setter access. But a
  // setter might not exist.
  if (const ObjCImplicitSetterGetterRefExpr *Expr =
        dyn_cast<ObjCImplicitSetterGetterRefExpr>(E)) {
    if (Expr->getSetterMethod() == 0)
      return Cl::CM_NoSetterProperty;
  }

  CanQualType CT = Ctx.getCanonicalType(E->getType());
  // Const stuff is obviously not modifiable.
  if (CT.isConstQualified())
    return Cl::CM_ConstQualified;
  // Arrays are not modifiable, only their elements are.
  if (CT->isArrayType())
    return Cl::CM_ArrayType;
  // Incomplete types are not modifiable.
  if (CT->isIncompleteType())
    return Cl::CM_IncompleteType;

  // Records with any const fields (recursively) are not modifiable.
  if (const RecordType *R = CT->getAs<RecordType>()) {
    assert(!Ctx.getLangOptions().CPlusPlus &&
           "C++ struct assignment should be resolved by the "
           "copy assignment operator.");
    if (R->hasConstFields())
      return Cl::CM_ConstQualified;
  }

  return Cl::CM_Modifiable;
}

bool ArgTypeResult::matchesType(ASTContext &C, QualType argTy) const {
  switch (K) {
    case InvalidTy:
      assert(false && "ArgTypeResult must be valid");
      return true;

    case UnknownTy:
      return true;

    case SpecificTy: {
      argTy = C.getCanonicalType(argTy).getUnqualifiedType();
      if (T == argTy)
        return true;
      // Check for "compatible types".
      if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
        switch (BT->getKind()) {
          default:
            break;
          case BuiltinType::Char_S:
          case BuiltinType::SChar:
            return T == C.UnsignedCharTy;
          case BuiltinType::Char_U:
          case BuiltinType::UChar:                    
            return T == C.SignedCharTy;
          case BuiltinType::Short:
            return T == C.UnsignedShortTy;
          case BuiltinType::UShort:
            return T == C.ShortTy;
          case BuiltinType::Int:
            return T == C.UnsignedIntTy;
          case BuiltinType::UInt:
            return T == C.IntTy;
          case BuiltinType::Long:
            return T == C.UnsignedLongTy;
          case BuiltinType::ULong:
            return T == C.LongTy;
          case BuiltinType::LongLong:
            return T == C.UnsignedLongLongTy;
          case BuiltinType::ULongLong:
            return T == C.LongLongTy;
        }
      return false;
    }

    case CStrTy: {
      const PointerType *PT = argTy->getAs<PointerType>();
      if (!PT)
        return false;
      QualType pointeeTy = PT->getPointeeType();
      if (const BuiltinType *BT = pointeeTy->getAs<BuiltinType>())
        switch (BT->getKind()) {
          case BuiltinType::Void:
          case BuiltinType::Char_U:
          case BuiltinType::UChar:
          case BuiltinType::Char_S:
          case BuiltinType::SChar:
            return true;
          default:
            break;
        }

      return false;
    }

    case WCStrTy: {
      const PointerType *PT = argTy->getAs<PointerType>();
      if (!PT)
        return false;
      QualType pointeeTy =
        C.getCanonicalType(PT->getPointeeType()).getUnqualifiedType();
      return pointeeTy == C.getWCharType();
    }
    
    case WIntTy: {
      // Instead of doing a lookup for the definition of 'wint_t' (which
      // is defined by the system headers) instead see if wchar_t and
      // the argument type promote to the same type.
      QualType PromoWChar =
        C.getWCharType()->isPromotableIntegerType() 
          ? C.getPromotedIntegerType(C.getWCharType()) : C.getWCharType();
      QualType PromoArg = 
        argTy->isPromotableIntegerType()
          ? C.getPromotedIntegerType(argTy) : argTy;
      
      PromoWChar = C.getCanonicalType(PromoWChar).getUnqualifiedType();
      PromoArg = C.getCanonicalType(PromoArg).getUnqualifiedType();
      
      return PromoWChar == PromoArg;
    }

    case CPointerTy:
      return argTy->isPointerType() || argTy->isObjCObjectPointerType() ||
        argTy->isNullPtrType();

    case ObjCPointerTy:
      return argTy->getAs<ObjCObjectPointerType>() != NULL;
  }

  // FIXME: Should be unreachable, but Clang is currently emitting
  // a warning.
//.........这里部分代码省略.........