xref: /external/clang/include/clang/AST/Expr.h

//===--- Expr.h - Classes for representing expressions ----------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file defines the Expr interface and subclasses.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_EXPR_H
#define LLVM_CLANG_AST_EXPR_H

#include "clang/AST/APValue.h"
#include "clang/AST/ASTVector.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclAccessPair.h"
#include "clang/AST/OperationKinds.h"
#include "clang/AST/Stmt.h"
#include "clang/AST/TemplateBase.h"
#include "clang/AST/Type.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Basic/TypeTraits.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Compiler.h"

namespace clang {
  class APValue;
  class ASTContext;
  class BlockDecl;
  class CXXBaseSpecifier;
  class CXXMemberCallExpr;
  class CXXOperatorCallExpr;
  class CastExpr;
  class Decl;
  class IdentifierInfo;
  class MaterializeTemporaryExpr;
  class NamedDecl;
  class ObjCPropertyRefExpr;
  class OpaqueValueExpr;
  class ParmVarDecl;
  class TargetInfo;
  class ValueDecl;

/// \brief A simple array of base specifiers.
typedef SmallVector<CXXBaseSpecifier*, 4> CXXCastPath;

/// \brief An adjustment to be made to the temporary created when emitting a
/// reference binding, which accesses a particular subobject of that temporary.
struct SubobjectAdjustment {
  enum {
    DerivedToBaseAdjustment,
    FieldAdjustment,
    MemberPointerAdjustment
  } Kind;


  struct DTB {
    const CastExpr *BasePath;
    const CXXRecordDecl *DerivedClass;
  };

  struct P {
    const MemberPointerType *MPT;
    Expr *RHS;
  };

  union {
    struct DTB DerivedToBase;
    FieldDecl *Field;
    struct P Ptr;
  };

  SubobjectAdjustment(const CastExpr *BasePath,
                      const CXXRecordDecl *DerivedClass)
    : Kind(DerivedToBaseAdjustment) {
    DerivedToBase.BasePath = BasePath;
    DerivedToBase.DerivedClass = DerivedClass;
  }

  SubobjectAdjustment(FieldDecl *Field)
    : Kind(FieldAdjustment) {
    this->Field = Field;
  }

  SubobjectAdjustment(const MemberPointerType *MPT, Expr *RHS)
    : Kind(MemberPointerAdjustment) {
    this->Ptr.MPT = MPT;
    this->Ptr.RHS = RHS;
  }
};

/// Expr - This represents one expression.  Note that Expr's are subclasses of
/// Stmt.  This allows an expression to be transparently used any place a Stmt
/// is required.
///
class Expr : public Stmt {
  QualType TR;

protected:
  Expr(StmtClass SC, QualType T, ExprValueKind VK, ExprObjectKind OK,
       bool TD, bool VD, bool ID, bool ContainsUnexpandedParameterPack)
    : Stmt(SC)
  {
    ExprBits.TypeDependent = TD;
    ExprBits.ValueDependent = VD;
    ExprBits.InstantiationDependent = ID;
    ExprBits.ValueKind = VK;
    ExprBits.ObjectKind = OK;
    ExprBits.ContainsUnexpandedParameterPack = ContainsUnexpandedParameterPack;
    setType(T);
  }

  /// \brief Construct an empty expression.
  explicit Expr(StmtClass SC, EmptyShell) : Stmt(SC) { }

public:
  QualType getType() const { return TR; }
  void setType(QualType t) {
    // In C++, the type of an expression is always adjusted so that it
    // will not have reference type an expression will never have
    // reference type (C++ [expr]p6). Use
    // QualType::getNonReferenceType() to retrieve the non-reference
    // type. Additionally, inspect Expr::isLvalue to determine whether
    // an expression that is adjusted in this manner should be
    // considered an lvalue.
    assert((t.isNull() || !t->isReferenceType()) &&
           "Expressions can't have reference type");

    TR = t;
  }

  /// isValueDependent - Determines whether this expression is
  /// value-dependent (C++ [temp.dep.constexpr]). For example, the
  /// array bound of "Chars" in the following example is
  /// value-dependent.
  /// @code
  /// template<int Size, char (&Chars)[Size]> struct meta_string;
  /// @endcode
  bool isValueDependent() const { return ExprBits.ValueDependent; }

  /// \brief Set whether this expression is value-dependent or not.
  void setValueDependent(bool VD) {
    ExprBits.ValueDependent = VD;
    if (VD)
      ExprBits.InstantiationDependent = true;
  }

  /// isTypeDependent - Determines whether this expression is
  /// type-dependent (C++ [temp.dep.expr]), which means that its type
  /// could change from one template instantiation to the next. For
  /// example, the expressions "x" and "x + y" are type-dependent in
  /// the following code, but "y" is not type-dependent:
  /// @code
  /// template<typename T>
  /// void add(T x, int y) {
  ///   x + y;
  /// }
  /// @endcode
  bool isTypeDependent() const { return ExprBits.TypeDependent; }

  /// \brief Set whether this expression is type-dependent or not.
  void setTypeDependent(bool TD) {
    ExprBits.TypeDependent = TD;
    if (TD)
      ExprBits.InstantiationDependent = true;
  }

  /// \brief Whether this expression is instantiation-dependent, meaning that
  /// it depends in some way on a template parameter, even if neither its type
  /// nor (constant) value can change due to the template instantiation.
  ///
  /// In the following example, the expression \c sizeof(sizeof(T() + T())) is
  /// instantiation-dependent (since it involves a template parameter \c T), but
  /// is neither type- nor value-dependent, since the type of the inner
  /// \c sizeof is known (\c std::size_t) and therefore the size of the outer
  /// \c sizeof is known.
  ///
  /// \code
  /// template<typename T>
  /// void f(T x, T y) {
  ///   sizeof(sizeof(T() + T());
  /// }
  /// \endcode
  ///
  bool isInstantiationDependent() const {
    return ExprBits.InstantiationDependent;
  }

  /// \brief Set whether this expression is instantiation-dependent or not.
  void setInstantiationDependent(bool ID) {
    ExprBits.InstantiationDependent = ID;
  }

  /// \brief Whether this expression contains an unexpanded parameter
  /// pack (for C++11 variadic templates).
  ///
  /// Given the following function template:
  ///
  /// \code
  /// template<typename F, typename ...Types>
  /// void forward(const F &f, Types &&...args) {
  ///   f(static_cast<Types&&>(args)...);
  /// }
  /// \endcode
  ///
  /// The expressions \c args and \c static_cast<Types&&>(args) both
  /// contain parameter packs.
  bool containsUnexpandedParameterPack() const {
    return ExprBits.ContainsUnexpandedParameterPack;
  }

  /// \brief Set the bit that describes whether this expression
  /// contains an unexpanded parameter pack.
  void setContainsUnexpandedParameterPack(bool PP = true) {
    ExprBits.ContainsUnexpandedParameterPack = PP;
  }

  /// getExprLoc - Return the preferred location for the arrow when diagnosing
  /// a problem with a generic expression.
  SourceLocation getExprLoc() const LLVM_READONLY;

  /// isUnusedResultAWarning - Return true if this immediate expression should
  /// be warned about if the result is unused.  If so, fill in expr, location,
  /// and ranges with expr to warn on and source locations/ranges appropriate
  /// for a warning.
  bool isUnusedResultAWarning(const Expr *&WarnExpr, SourceLocation &Loc,
                              SourceRange &R1, SourceRange &R2,
                              ASTContext &Ctx) const;

  /// isLValue - True if this expression is an "l-value" according to
  /// the rules of the current language.  C and C++ give somewhat
  /// different rules for this concept, but in general, the result of
  /// an l-value expression identifies a specific object whereas the
  /// result of an r-value expression is a value detached from any
  /// specific storage.
  ///
  /// C++11 divides the concept of "r-value" into pure r-values
  /// ("pr-values") and so-called expiring values ("x-values"), which
  /// identify specific objects that can be safely cannibalized for
  /// their resources.  This is an unfortunate abuse of terminology on
  /// the part of the C++ committee.  In Clang, when we say "r-value",
  /// we generally mean a pr-value.
  bool isLValue() const { return getValueKind() == VK_LValue; }
  bool isRValue() const { return getValueKind() == VK_RValue; }
  bool isXValue() const { return getValueKind() == VK_XValue; }
  bool isGLValue() const { return getValueKind() != VK_RValue; }

  enum LValueClassification {
    LV_Valid,
    LV_NotObjectType,
    LV_IncompleteVoidType,
    LV_DuplicateVectorComponents,
    LV_InvalidExpression,
    LV_InvalidMessageExpression,
    LV_MemberFunction,
    LV_SubObjCPropertySetting,
    LV_ClassTemporary,
    LV_ArrayTemporary
  };
  /// Reasons why an expression might not be an l-value.
  LValueClassification ClassifyLValue(ASTContext &Ctx) const;

  enum isModifiableLvalueResult {
    MLV_Valid,
    MLV_NotObjectType,
    MLV_IncompleteVoidType,
    MLV_DuplicateVectorComponents,
    MLV_InvalidExpression,
    MLV_LValueCast,           // Specialized form of MLV_InvalidExpression.
    MLV_IncompleteType,
    MLV_ConstQualified,
    MLV_ArrayType,
    MLV_NoSetterProperty,
    MLV_MemberFunction,
    MLV_SubObjCPropertySetting,
    MLV_InvalidMessageExpression,
    MLV_ClassTemporary,
    MLV_ArrayTemporary
  };
  /// isModifiableLvalue - C99 6.3.2.1: an lvalue that does not have array type,
  /// does not have an incomplete type, does not have a const-qualified type,
  /// and if it is a structure or union, does not have any member (including,
  /// recursively, any member or element of all contained aggregates or unions)
  /// with a const-qualified type.
  ///
  /// \param Loc [in,out] - A source location which *may* be filled
  /// in with the location of the expression making this a
  /// non-modifiable lvalue, if specified.
  isModifiableLvalueResult
  isModifiableLvalue(ASTContext &Ctx, SourceLocation *Loc = nullptr) const;

  /// \brief The return type of classify(). Represents the C++11 expression
  ///        taxonomy.
  class Classification {
  public:
    /// \brief The various classification results. Most of these mean prvalue.
    enum Kinds {
      CL_LValue,
      CL_XValue,
      CL_Function, // Functions cannot be lvalues in C.
      CL_Void, // Void cannot be an lvalue in C.
      CL_AddressableVoid, // Void expression whose address can be taken in C.
      CL_DuplicateVectorComponents, // A vector shuffle with dupes.
      CL_MemberFunction, // An expression referring to a member function
      CL_SubObjCPropertySetting,
      CL_ClassTemporary, // A temporary of class type, or subobject thereof.
      CL_ArrayTemporary, // A temporary of array type.
      CL_ObjCMessageRValue, // ObjC message is an rvalue
      CL_PRValue // A prvalue for any other reason, of any other type
    };
    /// \brief The results of modification testing.
    enum ModifiableType {
      CM_Untested, // testModifiable was false.
      CM_Modifiable,
      CM_RValue, // Not modifiable because it's an rvalue
      CM_Function, // Not modifiable because it's a function; C++ only
      CM_LValueCast, // Same as CM_RValue, but indicates GCC cast-as-lvalue ext
      CM_NoSetterProperty,// Implicit assignment to ObjC property without setter
      CM_ConstQualified,
      CM_ArrayType,
      CM_IncompleteType
    };

  private:
    friend class Expr;

    unsigned short Kind;
    unsigned short Modifiable;

    explicit Classification(Kinds k, ModifiableType m)
      : Kind(k), Modifiable(m)
    {}

  public:
    Classification() {}

    Kinds getKind() const { return static_cast<Kinds>(Kind); }
    ModifiableType getModifiable() const {
      assert(Modifiable != CM_Untested && "Did not test for modifiability.");
      return static_cast<ModifiableType>(Modifiable);
    }
    bool isLValue() const { return Kind == CL_LValue; }
    bool isXValue() const { return Kind == CL_XValue; }
    bool isGLValue() const { return Kind <= CL_XValue; }
    bool isPRValue() const { return Kind >= CL_Function; }
    bool isRValue() const { return Kind >= CL_XValue; }
    bool isModifiable() const { return getModifiable() == CM_Modifiable; }

    /// \brief Create a simple, modifiably lvalue
    static Classification makeSimpleLValue() {
      return Classification(CL_LValue, CM_Modifiable);
    }

  };
  /// \brief Classify - Classify this expression according to the C++11
  ///        expression taxonomy.
  ///
  /// C++11 defines ([basic.lval]) a new taxonomy of expressions to replace the
  /// old lvalue vs rvalue. This function determines the type of expression this
  /// is. There are three expression types:
  /// - lvalues are classical lvalues as in C++03.
  /// - prvalues are equivalent to rvalues in C++03.
  /// - xvalues are expressions yielding unnamed rvalue references, e.g. a
  ///   function returning an rvalue reference.
  /// lvalues and xvalues are collectively referred to as glvalues, while
  /// prvalues and xvalues together form rvalues.
  Classification Classify(ASTContext &Ctx) const {
    return ClassifyImpl(Ctx, nullptr);
  }

  /// \brief ClassifyModifiable - Classify this expression according to the
  ///        C++11 expression taxonomy, and see if it is valid on the left side
  ///        of an assignment.
  ///
  /// This function extends classify in that it also tests whether the
  /// expression is modifiable (C99 6.3.2.1p1).
  /// \param Loc A source location that might be filled with a relevant location
  ///            if the expression is not modifiable.
  Classification ClassifyModifiable(ASTContext &Ctx, SourceLocation &Loc) const{
    return ClassifyImpl(Ctx, &Loc);
  }

  /// getValueKindForType - Given a formal return or parameter type,
  /// give its value kind.
  static ExprValueKind getValueKindForType(QualType T) {
    if (const ReferenceType *RT = T->getAs<ReferenceType>())
      return (isa<LValueReferenceType>(RT)
                ? VK_LValue
                : (RT->getPointeeType()->isFunctionType()
                     ? VK_LValue : VK_XValue));
    return VK_RValue;
  }

  /// getValueKind - The value kind that this expression produces.
  ExprValueKind getValueKind() const {
    return static_cast<ExprValueKind>(ExprBits.ValueKind);
  }

  /// getObjectKind - The object kind that this expression produces.
  /// Object kinds are meaningful only for expressions that yield an
  /// l-value or x-value.
  ExprObjectKind getObjectKind() const {
    return static_cast<ExprObjectKind>(ExprBits.ObjectKind);
  }

  bool isOrdinaryOrBitFieldObject() const {
    ExprObjectKind OK = getObjectKind();
    return (OK == OK_Ordinary || OK == OK_BitField);
  }

  /// setValueKind - Set the value kind produced by this expression.
  void setValueKind(ExprValueKind Cat) { ExprBits.ValueKind = Cat; }

  /// setObjectKind - Set the object kind produced by this expression.
  void setObjectKind(ExprObjectKind Cat) { ExprBits.ObjectKind = Cat; }

private:
  Classification ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const;

public:

  /// \brief Returns true if this expression is a gl-value that
  /// potentially refers to a bit-field.
  ///
  /// In C++, whether a gl-value refers to a bitfield is essentially
  /// an aspect of the value-kind type system.
  bool refersToBitField() const { return getObjectKind() == OK_BitField; }

  /// \brief If this expression refers to a bit-field, retrieve the
  /// declaration of that bit-field.
  ///
  /// Note that this returns a non-null pointer in subtly different
  /// places than refersToBitField returns true.  In particular, this can
  /// return a non-null pointer even for r-values loaded from
  /// bit-fields, but it will return null for a conditional bit-field.
  FieldDecl *getSourceBitField();

  const FieldDecl *getSourceBitField() const {
    return const_cast<Expr*>(this)->getSourceBitField();
  }

  /// \brief If this expression is an l-value for an Objective C
  /// property, find the underlying property reference expression.
  const ObjCPropertyRefExpr *getObjCProperty() const;

  /// \brief Check if this expression is the ObjC 'self' implicit parameter.
  bool isObjCSelfExpr() const;

  /// \brief Returns whether this expression refers to a vector element.
  bool refersToVectorElement() const;

  /// \brief Returns whether this expression has a placeholder type.
  bool hasPlaceholderType() const {
    return getType()->isPlaceholderType();
  }

  /// \brief Returns whether this expression has a specific placeholder type.
  bool hasPlaceholderType(BuiltinType::Kind K) const {
    assert(BuiltinType::isPlaceholderTypeKind(K));
    if (const BuiltinType *BT = dyn_cast<BuiltinType>(getType()))
      return BT->getKind() == K;
    return false;
  }

  /// isKnownToHaveBooleanValue - Return true if this is an integer expression
  /// that is known to return 0 or 1.  This happens for _Bool/bool expressions
  /// but also int expressions which are produced by things like comparisons in
  /// C.
  bool isKnownToHaveBooleanValue() const;

  /// isIntegerConstantExpr - Return true if this expression is a valid integer
  /// constant expression, and, if so, return its value in Result.  If not a
  /// valid i-c-e, return false and fill in Loc (if specified) with the location
  /// of the invalid expression.
  ///
  /// Note: This does not perform the implicit conversions required by C++11
  /// [expr.const]p5.
  bool isIntegerConstantExpr(llvm::APSInt &Result, const ASTContext &Ctx,
                             SourceLocation *Loc = nullptr,
                             bool isEvaluated = true) const;
  bool isIntegerConstantExpr(const ASTContext &Ctx,
                             SourceLocation *Loc = nullptr) const;

  /// isCXX98IntegralConstantExpr - Return true if this expression is an
  /// integral constant expression in C++98. Can only be used in C++.
  bool isCXX98IntegralConstantExpr(const ASTContext &Ctx) const;

  /// isCXX11ConstantExpr - Return true if this expression is a constant
  /// expression in C++11. Can only be used in C++.
  ///
  /// Note: This does not perform the implicit conversions required by C++11
  /// [expr.const]p5.
  bool isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result = nullptr,
                           SourceLocation *Loc = nullptr) const;

  /// isPotentialConstantExpr - Return true if this function's definition
  /// might be usable in a constant expression in C++11, if it were marked
  /// constexpr. Return false if the function can never produce a constant
  /// expression, along with diagnostics describing why not.
  static bool isPotentialConstantExpr(const FunctionDecl *FD,
                                      SmallVectorImpl<
                                        PartialDiagnosticAt> &Diags);

  /// isPotentialConstantExprUnevaluted - Return true if this expression might
  /// be usable in a constant expression in C++11 in an unevaluated context, if
  /// it were in function FD marked constexpr. Return false if the function can
  /// never produce a constant expression, along with diagnostics describing
  /// why not.
  static bool isPotentialConstantExprUnevaluated(Expr *E,
                                                 const FunctionDecl *FD,
                                                 SmallVectorImpl<
                                                   PartialDiagnosticAt> &Diags);

  /// isConstantInitializer - Returns true if this expression can be emitted to
  /// IR as a constant, and thus can be used as a constant initializer in C.
  /// If this expression is not constant and Culprit is non-null,
  /// it is used to store the address of first non constant expr.
  bool isConstantInitializer(ASTContext &Ctx, bool ForRef,
                             const Expr **Culprit = nullptr) const;

  /// EvalStatus is a struct with detailed info about an evaluation in progress.
  struct EvalStatus {
    /// HasSideEffects - Whether the evaluated expression has side effects.
    /// For example, (f() && 0) can be folded, but it still has side effects.
    bool HasSideEffects;

    /// Diag - If this is non-null, it will be filled in with a stack of notes
    /// indicating why evaluation failed (or why it failed to produce a constant
    /// expression).
    /// If the expression is unfoldable, the notes will indicate why it's not
    /// foldable. If the expression is foldable, but not a constant expression,
    /// the notes will describes why it isn't a constant expression. If the
    /// expression *is* a constant expression, no notes will be produced.
    SmallVectorImpl<PartialDiagnosticAt> *Diag;

    EvalStatus() : HasSideEffects(false), Diag(nullptr) {}

    // hasSideEffects - Return true if the evaluated expression has
    // side effects.
    bool hasSideEffects() const {
      return HasSideEffects;
    }
  };

  /// EvalResult is a struct with detailed info about an evaluated expression.
  struct EvalResult : EvalStatus {
    /// Val - This is the value the expression can be folded to.
    APValue Val;

    // isGlobalLValue - Return true if the evaluated lvalue expression
    // is global.
    bool isGlobalLValue() const;
  };

  /// EvaluateAsRValue - Return true if this is a constant which we can fold to
  /// an rvalue using any crazy technique (that has nothing to do with language
  /// standards) that we want to, even if the expression has side-effects. If
  /// this function returns true, it returns the folded constant in Result. If
  /// the expression is a glvalue, an lvalue-to-rvalue conversion will be
  /// applied.
  bool EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const;

  /// EvaluateAsBooleanCondition - Return true if this is a constant
  /// which we we can fold and convert to a boolean condition using
  /// any crazy technique that we want to, even if the expression has
  /// side-effects.
  bool EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx) const;

  enum SideEffectsKind { SE_NoSideEffects, SE_AllowSideEffects };

  /// EvaluateAsInt - Return true if this is a constant which we can fold and
  /// convert to an integer, using any crazy technique that we want to.
  bool EvaluateAsInt(llvm::APSInt &Result, const ASTContext &Ctx,
                     SideEffectsKind AllowSideEffects = SE_NoSideEffects) const;

  /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
  /// constant folded without side-effects, but discard the result.
  bool isEvaluatable(const ASTContext &Ctx) const;

  /// HasSideEffects - This routine returns true for all those expressions
  /// which have any effect other than producing a value. Example is a function
  /// call, volatile variable read, or throwing an exception.
  bool HasSideEffects(const ASTContext &Ctx) const;

  /// \brief Determine whether this expression involves a call to any function
  /// that is not trivial.
  bool hasNonTrivialCall(ASTContext &Ctx);

  /// EvaluateKnownConstInt - Call EvaluateAsRValue and return the folded
  /// integer. This must be called on an expression that constant folds to an
  /// integer.
  llvm::APSInt EvaluateKnownConstInt(const ASTContext &Ctx,
                    SmallVectorImpl<PartialDiagnosticAt> *Diag = nullptr) const;

  void EvaluateForOverflow(const ASTContext &Ctx) const;

  /// EvaluateAsLValue - Evaluate an expression to see if we can fold it to an
  /// lvalue with link time known address, with no side-effects.
  bool EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const;

  /// EvaluateAsInitializer - Evaluate an expression as if it were the
  /// initializer of the given declaration. Returns true if the initializer
  /// can be folded to a constant, and produces any relevant notes. In C++11,
  /// notes will be produced if the expression is not a constant expression.
  bool EvaluateAsInitializer(APValue &Result, const ASTContext &Ctx,
                             const VarDecl *VD,
                             SmallVectorImpl<PartialDiagnosticAt> &Notes) const;

  /// EvaluateWithSubstitution - Evaluate an expression as if from the context
  /// of a call to the given function with the given arguments, inside an
  /// unevaluated context. Returns true if the expression could be folded to a
  /// constant.
  bool EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
                                const FunctionDecl *Callee,
                                ArrayRef<const Expr*> Args) const;

  /// \brief Enumeration used to describe the kind of Null pointer constant
  /// returned from \c isNullPointerConstant().
  enum NullPointerConstantKind {
    /// \brief Expression is not a Null pointer constant.
    NPCK_NotNull = 0,

    /// \brief Expression is a Null pointer constant built from a zero integer
    /// expression that is not a simple, possibly parenthesized, zero literal.
    /// C++ Core Issue 903 will classify these expressions as "not pointers"
    /// once it is adopted.
    /// http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#903
    NPCK_ZeroExpression,

    /// \brief Expression is a Null pointer constant built from a literal zero.
    NPCK_ZeroLiteral,

    /// \brief Expression is a C++11 nullptr.
    NPCK_CXX11_nullptr,

    /// \brief Expression is a GNU-style __null constant.
    NPCK_GNUNull
  };

  /// \brief Enumeration used to describe how \c isNullPointerConstant()
  /// should cope with value-dependent expressions.
  enum NullPointerConstantValueDependence {
    /// \brief Specifies that the expression should never be value-dependent.
    NPC_NeverValueDependent = 0,

    /// \brief Specifies that a value-dependent expression of integral or
    /// dependent type should be considered a null pointer constant.
    NPC_ValueDependentIsNull,

    /// \brief Specifies that a value-dependent expression should be considered
    /// to never be a null pointer constant.
    NPC_ValueDependentIsNotNull
  };

  /// isNullPointerConstant - C99 6.3.2.3p3 - Test if this reduces down to
  /// a Null pointer constant. The return value can further distinguish the
  /// kind of NULL pointer constant that was detected.
  NullPointerConstantKind isNullPointerConstant(
      ASTContext &Ctx,
      NullPointerConstantValueDependence NPC) const;

  /// isOBJCGCCandidate - Return true if this expression may be used in a read/
  /// write barrier.
  bool isOBJCGCCandidate(ASTContext &Ctx) const;

  /// \brief Returns true if this expression is a bound member function.
  bool isBoundMemberFunction(ASTContext &Ctx) const;

  /// \brief Given an expression of bound-member type, find the type
  /// of the member.  Returns null if this is an *overloaded* bound
  /// member expression.
  static QualType findBoundMemberType(const Expr *expr);

  /// IgnoreImpCasts - Skip past any implicit casts which might
  /// surround this expression.  Only skips ImplicitCastExprs.
  Expr *IgnoreImpCasts() LLVM_READONLY;

  /// IgnoreImplicit - Skip past any implicit AST nodes which might
  /// surround this expression.
  Expr *IgnoreImplicit() LLVM_READONLY {
    return cast<Expr>(Stmt::IgnoreImplicit());
  }

  const Expr *IgnoreImplicit() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreImplicit();
  }

  /// IgnoreParens - Ignore parentheses.  If this Expr is a ParenExpr, return
  ///  its subexpression.  If that subexpression is also a ParenExpr,
  ///  then this method recursively returns its subexpression, and so forth.
  ///  Otherwise, the method returns the current Expr.
  Expr *IgnoreParens() LLVM_READONLY;

  /// IgnoreParenCasts - Ignore parentheses and casts.  Strip off any ParenExpr
  /// or CastExprs, returning their operand.
  Expr *IgnoreParenCasts() LLVM_READONLY;

  /// Ignore casts.  Strip off any CastExprs, returning their operand.
  Expr *IgnoreCasts() LLVM_READONLY;

  /// IgnoreParenImpCasts - Ignore parentheses and implicit casts.  Strip off
  /// any ParenExpr or ImplicitCastExprs, returning their operand.
  Expr *IgnoreParenImpCasts() LLVM_READONLY;

  /// IgnoreConversionOperator - Ignore conversion operator. If this Expr is a
  /// call to a conversion operator, return the argument.
  Expr *IgnoreConversionOperator() LLVM_READONLY;

  const Expr *IgnoreConversionOperator() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreConversionOperator();
  }

  const Expr *IgnoreParenImpCasts() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreParenImpCasts();
  }

  /// Ignore parentheses and lvalue casts.  Strip off any ParenExpr and
  /// CastExprs that represent lvalue casts, returning their operand.
  Expr *IgnoreParenLValueCasts() LLVM_READONLY;

  const Expr *IgnoreParenLValueCasts() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreParenLValueCasts();
  }

  /// IgnoreParenNoopCasts - Ignore parentheses and casts that do not change the
  /// value (including ptr->int casts of the same size).  Strip off any
  /// ParenExpr or CastExprs, returning their operand.
  Expr *IgnoreParenNoopCasts(ASTContext &Ctx) LLVM_READONLY;

  /// Ignore parentheses and derived-to-base casts.
  Expr *ignoreParenBaseCasts() LLVM_READONLY;

  const Expr *ignoreParenBaseCasts() const LLVM_READONLY {
    return const_cast<Expr*>(this)->ignoreParenBaseCasts();
  }

  /// \brief Determine whether this expression is a default function argument.
  ///
  /// Default arguments are implicitly generated in the abstract syntax tree
  /// by semantic analysis for function calls, object constructions, etc. in
  /// C++. Default arguments are represented by \c CXXDefaultArgExpr nodes;
  /// this routine also looks through any implicit casts to determine whether
  /// the expression is a default argument.
  bool isDefaultArgument() const;

  /// \brief Determine whether the result of this expression is a
  /// temporary object of the given class type.
  bool isTemporaryObject(ASTContext &Ctx, const CXXRecordDecl *TempTy) const;

  /// \brief Whether this expression is an implicit reference to 'this' in C++.
  bool isImplicitCXXThis() const;

  const Expr *IgnoreImpCasts() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreImpCasts();
  }
  const Expr *IgnoreParens() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreParens();
  }
  const Expr *IgnoreParenCasts() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreParenCasts();
  }
  /// Strip off casts, but keep parentheses.
  const Expr *IgnoreCasts() const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreCasts();
  }

  const Expr *IgnoreParenNoopCasts(ASTContext &Ctx) const LLVM_READONLY {
    return const_cast<Expr*>(this)->IgnoreParenNoopCasts(Ctx);
  }

  static bool hasAnyTypeDependentArguments(ArrayRef<Expr *> Exprs);

  /// \brief For an expression of class type or pointer to class type,
  /// return the most derived class decl the expression is known to refer to.
  ///
  /// If this expression is a cast, this method looks through it to find the
  /// most derived decl that can be inferred from the expression.
  /// This is valid because derived-to-base conversions have undefined
  /// behavior if the object isn't dynamically of the derived type.
  const CXXRecordDecl *getBestDynamicClassType() const;

  /// Walk outwards from an expression we want to bind a reference to and
  /// find the expression whose lifetime needs to be extended. Record
  /// the LHSs of comma expressions and adjustments needed along the path.
  const Expr *skipRValueSubobjectAdjustments(
      SmallVectorImpl<const Expr *> &CommaLHS,
      SmallVectorImpl<SubobjectAdjustment> &Adjustments) const;

  static bool classof(const Stmt *T) {
    return T->getStmtClass() >= firstExprConstant &&
           T->getStmtClass() <= lastExprConstant;
  }
};


//===----------------------------------------------------------------------===//
// Primary Expressions.
//===----------------------------------------------------------------------===//

/// OpaqueValueExpr - An expression referring to an opaque object of a
/// fixed type and value class.  These don't correspond to concrete
/// syntax; instead they're used to express operations (usually copy
/// operations) on values whose source is generally obvious from
/// context.
class OpaqueValueExpr : public Expr {
  friend class ASTStmtReader;
  Expr *SourceExpr;
  SourceLocation Loc;

public:
  OpaqueValueExpr(SourceLocation Loc, QualType T, ExprValueKind VK,
                  ExprObjectKind OK = OK_Ordinary,
                  Expr *SourceExpr = nullptr)
    : Expr(OpaqueValueExprClass, T, VK, OK,
           T->isDependentType(),
           T->isDependentType() ||
           (SourceExpr && SourceExpr->isValueDependent()),
           T->isInstantiationDependentType(),
           false),
      SourceExpr(SourceExpr), Loc(Loc) {
  }

  /// Given an expression which invokes a copy constructor --- i.e.  a
  /// CXXConstructExpr, possibly wrapped in an ExprWithCleanups ---
  /// find the OpaqueValueExpr that's the source of the construction.
  static const OpaqueValueExpr *findInCopyConstruct(const Expr *expr);

  explicit OpaqueValueExpr(EmptyShell Empty)
    : Expr(OpaqueValueExprClass, Empty) { }

  /// \brief Retrieve the location of this expression.
  SourceLocation getLocation() const { return Loc; }

  SourceLocation getLocStart() const LLVM_READONLY {
    return SourceExpr ? SourceExpr->getLocStart() : Loc;
  }
  SourceLocation getLocEnd() const LLVM_READONLY {
    return SourceExpr ? SourceExpr->getLocEnd() : Loc;
  }
  SourceLocation getExprLoc() const LLVM_READONLY {
    if (SourceExpr) return SourceExpr->getExprLoc();
    return Loc;
  }

  child_range children() { return child_range(); }

  /// The source expression of an opaque value expression is the
  /// expression which originally generated the value.  This is
  /// provided as a convenience for analyses that don't wish to
  /// precisely model the execution behavior of the program.
  ///
  /// The source expression is typically set when building the
  /// expression which binds the opaque value expression in the first
  /// place.
  Expr *getSourceExpr() const { return SourceExpr; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == OpaqueValueExprClass;
  }
};

/// \brief A reference to a declared variable, function, enum, etc.
/// [C99 6.5.1p2]
///
/// This encodes all the information about how a declaration is referenced
/// within an expression.
///
/// There are several optional constructs attached to DeclRefExprs only when
/// they apply in order to conserve memory. These are laid out past the end of
/// the object, and flags in the DeclRefExprBitfield track whether they exist:
///
///   DeclRefExprBits.HasQualifier:
///       Specifies when this declaration reference expression has a C++
///       nested-name-specifier.
///   DeclRefExprBits.HasFoundDecl:
///       Specifies when this declaration reference expression has a record of
///       a NamedDecl (different from the referenced ValueDecl) which was found
///       during name lookup and/or overload resolution.
///   DeclRefExprBits.HasTemplateKWAndArgsInfo:
///       Specifies when this declaration reference expression has an explicit
///       C++ template keyword and/or template argument list.
///   DeclRefExprBits.RefersToEnclosingLocal
///       Specifies when this declaration reference expression (validly)
///       refers to a local variable from a different function.
class DeclRefExpr : public Expr {
  /// \brief The declaration that we are referencing.
  ValueDecl *D;

  /// \brief The location of the declaration name itself.
  SourceLocation Loc;

  /// \brief Provides source/type location info for the declaration name
  /// embedded in D.
  DeclarationNameLoc DNLoc;

  /// \brief Helper to retrieve the optional NestedNameSpecifierLoc.
  NestedNameSpecifierLoc &getInternalQualifierLoc() {
    assert(hasQualifier());
    return *reinterpret_cast<NestedNameSpecifierLoc *>(this + 1);
  }

  /// \brief Helper to retrieve the optional NestedNameSpecifierLoc.
  const NestedNameSpecifierLoc &getInternalQualifierLoc() const {
    return const_cast<DeclRefExpr *>(this)->getInternalQualifierLoc();
  }

  /// \brief Test whether there is a distinct FoundDecl attached to the end of
  /// this DRE.
  bool hasFoundDecl() const { return DeclRefExprBits.HasFoundDecl; }

  /// \brief Helper to retrieve the optional NamedDecl through which this
  /// reference occurred.
  NamedDecl *&getInternalFoundDecl() {
    assert(hasFoundDecl());
    if (hasQualifier())
      return *reinterpret_cast<NamedDecl **>(&getInternalQualifierLoc() + 1);
    return *reinterpret_cast<NamedDecl **>(this + 1);
  }

  /// \brief Helper to retrieve the optional NamedDecl through which this
  /// reference occurred.
  NamedDecl *getInternalFoundDecl() const {
    return const_cast<DeclRefExpr *>(this)->getInternalFoundDecl();
  }

  DeclRefExpr(const ASTContext &Ctx,
              NestedNameSpecifierLoc QualifierLoc,
              SourceLocation TemplateKWLoc,
              ValueDecl *D, bool refersToEnclosingLocal,
              const DeclarationNameInfo &NameInfo,
              NamedDecl *FoundD,
              const TemplateArgumentListInfo *TemplateArgs,
              QualType T, ExprValueKind VK);

  /// \brief Construct an empty declaration reference expression.
  explicit DeclRefExpr(EmptyShell Empty)
    : Expr(DeclRefExprClass, Empty) { }

  /// \brief Computes the type- and value-dependence flags for this
  /// declaration reference expression.
  void computeDependence(const ASTContext &C);

public:
  DeclRefExpr(ValueDecl *D, bool refersToEnclosingLocal, QualType T,
              ExprValueKind VK, SourceLocation L,
              const DeclarationNameLoc &LocInfo = DeclarationNameLoc())
    : Expr(DeclRefExprClass, T, VK, OK_Ordinary, false, false, false, false),
      D(D), Loc(L), DNLoc(LocInfo) {
    DeclRefExprBits.HasQualifier = 0;
    DeclRefExprBits.HasTemplateKWAndArgsInfo = 0;
    DeclRefExprBits.HasFoundDecl = 0;
    DeclRefExprBits.HadMultipleCandidates = 0;
    DeclRefExprBits.RefersToEnclosingLocal = refersToEnclosingLocal;
    computeDependence(D->getASTContext());
  }

  static DeclRefExpr *
  Create(const ASTContext &Context, NestedNameSpecifierLoc QualifierLoc,
         SourceLocation TemplateKWLoc, ValueDecl *D, bool isEnclosingLocal,
         SourceLocation NameLoc, QualType T, ExprValueKind VK,
         NamedDecl *FoundD = nullptr,
         const TemplateArgumentListInfo *TemplateArgs = nullptr);

  static DeclRefExpr *
  Create(const ASTContext &Context, NestedNameSpecifierLoc QualifierLoc,
         SourceLocation TemplateKWLoc, ValueDecl *D, bool isEnclosingLocal,
         const DeclarationNameInfo &NameInfo, QualType T, ExprValueKind VK,
         NamedDecl *FoundD = nullptr,
         const TemplateArgumentListInfo *TemplateArgs = nullptr);

  /// \brief Construct an empty declaration reference expression.
  static DeclRefExpr *CreateEmpty(const ASTContext &Context,
                                  bool HasQualifier,
                                  bool HasFoundDecl,
                                  bool HasTemplateKWAndArgsInfo,
                                  unsigned NumTemplateArgs);

  ValueDecl *getDecl() { return D; }
  const ValueDecl *getDecl() const { return D; }
  void setDecl(ValueDecl *NewD) { D = NewD; }

  DeclarationNameInfo getNameInfo() const {
    return DeclarationNameInfo(getDecl()->getDeclName(), Loc, DNLoc);
  }

  SourceLocation getLocation() const { return Loc; }
  void setLocation(SourceLocation L) { Loc = L; }
  SourceLocation getLocStart() const LLVM_READONLY;
  SourceLocation getLocEnd() const LLVM_READONLY;

  /// \brief Determine whether this declaration reference was preceded by a
  /// C++ nested-name-specifier, e.g., \c N::foo.
  bool hasQualifier() const { return DeclRefExprBits.HasQualifier; }

  /// \brief If the name was qualified, retrieves the nested-name-specifier
  /// that precedes the name. Otherwise, returns NULL.
  NestedNameSpecifier *getQualifier() const {
    if (!hasQualifier())
      return nullptr;

    return getInternalQualifierLoc().getNestedNameSpecifier();
  }

  /// \brief If the name was qualified, retrieves the nested-name-specifier
  /// that precedes the name, with source-location information.
  NestedNameSpecifierLoc getQualifierLoc() const {
    if (!hasQualifier())
      return NestedNameSpecifierLoc();

    return getInternalQualifierLoc();
  }

  /// \brief Get the NamedDecl through which this reference occurred.
  ///
  /// This Decl may be different from the ValueDecl actually referred to in the
  /// presence of using declarations, etc. It always returns non-NULL, and may
  /// simple return the ValueDecl when appropriate.
  NamedDecl *getFoundDecl() {
    return hasFoundDecl() ? getInternalFoundDecl() : D;
  }

  /// \brief Get the NamedDecl through which this reference occurred.
  /// See non-const variant.
  const NamedDecl *getFoundDecl() const {
    return hasFoundDecl() ? getInternalFoundDecl() : D;
  }

  bool hasTemplateKWAndArgsInfo() const {
    return DeclRefExprBits.HasTemplateKWAndArgsInfo;
  }

  /// \brief Return the optional template keyword and arguments info.
  ASTTemplateKWAndArgsInfo *getTemplateKWAndArgsInfo() {
    if (!hasTemplateKWAndArgsInfo())
      return nullptr;

    if (hasFoundDecl())
      return reinterpret_cast<ASTTemplateKWAndArgsInfo *>(
        &getInternalFoundDecl() + 1);

    if (hasQualifier())
      return reinterpret_cast<ASTTemplateKWAndArgsInfo *>(
        &getInternalQualifierLoc() + 1);

    return reinterpret_cast<ASTTemplateKWAndArgsInfo *>(this + 1);
  }

  /// \brief Return the optional template keyword and arguments info.
  const ASTTemplateKWAndArgsInfo *getTemplateKWAndArgsInfo() const {
    return const_cast<DeclRefExpr*>(this)->getTemplateKWAndArgsInfo();
  }

  /// \brief Retrieve the location of the template keyword preceding
  /// this name, if any.
  SourceLocation getTemplateKeywordLoc() const {
    if (!hasTemplateKWAndArgsInfo()) return SourceLocation();
    return getTemplateKWAndArgsInfo()->getTemplateKeywordLoc();
  }

  /// \brief Retrieve the location of the left angle bracket starting the
  /// explicit template argument list following the name, if any.
  SourceLocation getLAngleLoc() const {
    if (!hasTemplateKWAndArgsInfo()) return SourceLocation();
    return getTemplateKWAndArgsInfo()->LAngleLoc;
  }

  /// \brief Retrieve the location of the right angle bracket ending the
  /// explicit template argument list following the name, if any.
  SourceLocation getRAngleLoc() const {
    if (!hasTemplateKWAndArgsInfo()) return SourceLocation();
    return getTemplateKWAndArgsInfo()->RAngleLoc;
  }

  /// \brief Determines whether the name in this declaration reference
  /// was preceded by the template keyword.
  bool hasTemplateKeyword() const { return getTemplateKeywordLoc().isValid(); }

  /// \brief Determines whether this declaration reference was followed by an
  /// explicit template argument list.
  bool hasExplicitTemplateArgs() const { return getLAngleLoc().isValid(); }

  /// \brief Retrieve the explicit template argument list that followed the
  /// member template name.
  ASTTemplateArgumentListInfo &getExplicitTemplateArgs() {
    assert(hasExplicitTemplateArgs());
    return *getTemplateKWAndArgsInfo();
  }

  /// \brief Retrieve the explicit template argument list that followed the
  /// member template name.
  const ASTTemplateArgumentListInfo &getExplicitTemplateArgs() const {
    return const_cast<DeclRefExpr *>(this)->getExplicitTemplateArgs();
  }

  /// \brief Retrieves the optional explicit template arguments.
  /// This points to the same data as getExplicitTemplateArgs(), but
  /// returns null if there are no explicit template arguments.
  const ASTTemplateArgumentListInfo *getOptionalExplicitTemplateArgs() const {
    if (!hasExplicitTemplateArgs()) return nullptr;
    return &getExplicitTemplateArgs();
  }

  /// \brief Copies the template arguments (if present) into the given
  /// structure.
  void copyTemplateArgumentsInto(TemplateArgumentListInfo &List) const {
    if (hasExplicitTemplateArgs())
      getExplicitTemplateArgs().copyInto(List);
  }

  /// \brief Retrieve the template arguments provided as part of this
  /// template-id.
  const TemplateArgumentLoc *getTemplateArgs() const {
    if (!hasExplicitTemplateArgs())
      return nullptr;

    return getExplicitTemplateArgs().getTemplateArgs();
  }

  /// \brief Retrieve the number of template arguments provided as part of this
  /// template-id.
  unsigned getNumTemplateArgs() const {
    if (!hasExplicitTemplateArgs())
      return 0;

    return getExplicitTemplateArgs().NumTemplateArgs;
  }

  /// \brief Returns true if this expression refers to a function that
  /// was resolved from an overloaded set having size greater than 1.
  bool hadMultipleCandidates() const {
    return DeclRefExprBits.HadMultipleCandidates;
  }
  /// \brief Sets the flag telling whether this expression refers to
  /// a function that was resolved from an overloaded set having size
  /// greater than 1.
  void setHadMultipleCandidates(bool V = true) {
    DeclRefExprBits.HadMultipleCandidates = V;
  }

  /// Does this DeclRefExpr refer to a local declaration from an
  /// enclosing function scope?
  bool refersToEnclosingLocal() const {
    return DeclRefExprBits.RefersToEnclosingLocal;
  }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == DeclRefExprClass;
  }

  // Iterators
  child_range children() { return child_range(); }

  friend class ASTStmtReader;
  friend class ASTStmtWriter;
};

/// PredefinedExpr - [C99 6.4.2.2] - A predefined identifier such as __func__.
class PredefinedExpr : public Expr {
public:
  enum IdentType {
    Func,
    Function,
    LFunction,  // Same as Function, but as wide string.
    FuncDName,
    FuncSig,
    PrettyFunction,
    /// PrettyFunctionNoVirtual - The same as PrettyFunction, except that the
    /// 'virtual' keyword is omitted for virtual member functions.
    PrettyFunctionNoVirtual
  };

private:
  SourceLocation Loc;
  IdentType Type;
public:
  PredefinedExpr(SourceLocation l, QualType type, IdentType IT)
    : Expr(PredefinedExprClass, type, VK_LValue, OK_Ordinary,
           type->isDependentType(), type->isDependentType(),
           type->isInstantiationDependentType(),
           /*ContainsUnexpandedParameterPack=*/false),
      Loc(l), Type(IT) {}

  /// \brief Construct an empty predefined expression.
  explicit PredefinedExpr(EmptyShell Empty)
    : Expr(PredefinedExprClass, Empty) { }

  IdentType getIdentType() const { return Type; }
  void setIdentType(IdentType IT) { Type = IT; }

  SourceLocation getLocation() const { return Loc; }
  void setLocation(SourceLocation L) { Loc = L; }

  static std::string ComputeName(IdentType IT, const Decl *CurrentDecl);

  SourceLocation getLocStart() const LLVM_READONLY { return Loc; }
  SourceLocation getLocEnd() const LLVM_READONLY { return Loc; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == PredefinedExprClass;
  }

  // Iterators
  child_range children() { return child_range(); }
};

/// \brief Used by IntegerLiteral/FloatingLiteral to store the numeric without
/// leaking memory.
///
/// For large floats/integers, APFloat/APInt will allocate memory from the heap
/// to represent these numbers.  Unfortunately, when we use a BumpPtrAllocator
/// to allocate IntegerLiteral/FloatingLiteral nodes the memory associated with
/// the APFloat/APInt values will never get freed. APNumericStorage uses
/// ASTContext's allocator for memory allocation.
class APNumericStorage {
  union {
    uint64_t VAL;    ///< Used to store the <= 64 bits integer value.
    uint64_t *pVal;  ///< Used to store the >64 bits integer value.
  };
  unsigned BitWidth;

  bool hasAllocation() const { return llvm::APInt::getNumWords(BitWidth) > 1; }

  APNumericStorage(const APNumericStorage &) LLVM_DELETED_FUNCTION;
  void operator=(const APNumericStorage &) LLVM_DELETED_FUNCTION;

protected:
  APNumericStorage() : VAL(0), BitWidth(0) { }

  llvm::APInt getIntValue() const {
    unsigned NumWords = llvm::APInt::getNumWords(BitWidth);
    if (NumWords > 1)
      return llvm::APInt(BitWidth, NumWords, pVal);
    else
      return llvm::APInt(BitWidth, VAL);
  }
  void setIntValue(const ASTContext &C, const llvm::APInt &Val);
};

class APIntStorage : private APNumericStorage {
public:
  llvm::APInt getValue() const { return getIntValue(); }
  void setValue(const ASTContext &C, const llvm::APInt &Val) {
    setIntValue(C, Val);
  }
};

class APFloatStorage : private APNumericStorage {
public:
  llvm::APFloat getValue(const llvm::fltSemantics &Semantics) const {
    return llvm::APFloat(Semantics, getIntValue());
  }
  void setValue(const ASTContext &C, const llvm::APFloat &Val) {
    setIntValue(C, Val.bitcastToAPInt());
  }
};

class IntegerLiteral : public Expr, public APIntStorage {
  SourceLocation Loc;

  /// \brief Construct an empty integer literal.
  explicit IntegerLiteral(EmptyShell Empty)
    : Expr(IntegerLiteralClass, Empty) { }

public:
  // type should be IntTy, LongTy, LongLongTy, UnsignedIntTy, UnsignedLongTy,
  // or UnsignedLongLongTy
  IntegerLiteral(const ASTContext &C, const llvm::APInt &V, QualType type,
                 SourceLocation l);

  /// \brief Returns a new integer literal with value 'V' and type 'type'.
  /// \param type - either IntTy, LongTy, LongLongTy, UnsignedIntTy,
  /// UnsignedLongTy, or UnsignedLongLongTy which should match the size of V
  /// \param V - the value that the returned integer literal contains.
  static IntegerLiteral *Create(const ASTContext &C, const llvm::APInt &V,
                                QualType type, SourceLocation l);
  /// \brief Returns a new empty integer literal.
  static IntegerLiteral *Create(const ASTContext &C, EmptyShell Empty);

  SourceLocation getLocStart() const LLVM_READONLY { return Loc; }
  SourceLocation getLocEnd() const LLVM_READONLY { return Loc; }

  /// \brief Retrieve the location of the literal.
  SourceLocation getLocation() const { return Loc; }

  void setLocation(SourceLocation Location) { Loc = Location; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == IntegerLiteralClass;
  }

  // Iterators
  child_range children() { return child_range(); }
};

class CharacterLiteral : public Expr {
public:
  enum CharacterKind {
    Ascii,
    Wide,
    UTF16,
    UTF32
  };

private:
  unsigned Value;
  SourceLocation Loc;
public:
  // type should be IntTy
  CharacterLiteral(unsigned value, CharacterKind kind, QualType type,
                   SourceLocation l)
    : Expr(CharacterLiteralClass, type, VK_RValue, OK_Ordinary, false, false,
           false, false),
      Value(value), Loc(l) {
    CharacterLiteralBits.Kind = kind;
  }

  /// \brief Construct an empty character literal.
  CharacterLiteral(EmptyShell Empty) : Expr(CharacterLiteralClass, Empty) { }

  SourceLocation getLocation() const { return Loc; }
  CharacterKind getKind() const {
    return static_cast<CharacterKind>(CharacterLiteralBits.Kind);
  }

  SourceLocation getLocStart() const LLVM_READONLY { return Loc; }
  SourceLocation getLocEnd() const LLVM_READONLY { return Loc; }

  unsigned getValue() const { return Value; }

  void setLocation(SourceLocation Location) { Loc = Location; }
  void setKind(CharacterKind kind) { CharacterLiteralBits.Kind = kind; }
  void setValue(unsigned Val) { Value = Val; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == CharacterLiteralClass;
  }

  // Iterators
  child_range children() { return child_range(); }
};

class FloatingLiteral : public Expr, private APFloatStorage {
  SourceLocation Loc;

  FloatingLiteral(const ASTContext &C, const llvm::APFloat &V, bool isexact,
                  QualType Type, SourceLocation L);

  /// \brief Construct an empty floating-point literal.
  explicit FloatingLiteral(const ASTContext &C, EmptyShell Empty);

public:
  static FloatingLiteral *Create(const ASTContext &C, const llvm::APFloat &V,
                                 bool isexact, QualType Type, SourceLocation L);
  static FloatingLiteral *Create(const ASTContext &C, EmptyShell Empty);

  llvm::APFloat getValue() const {
    return APFloatStorage::getValue(getSemantics());
  }
  void setValue(const ASTContext &C, const llvm::APFloat &Val) {
    assert(&getSemantics() == &Val.getSemantics() && "Inconsistent semantics");
    APFloatStorage::setValue(C, Val);
  }

  /// Get a raw enumeration value representing the floating-point semantics of
  /// this literal (32-bit IEEE, x87, ...), suitable for serialisation.
  APFloatSemantics getRawSemantics() const {
    return static_cast<APFloatSemantics>(FloatingLiteralBits.Semantics);
  }

  /// Set the raw enumeration value representing the floating-point semantics of
  /// this literal (32-bit IEEE, x87, ...), suitable for serialisation.
  void setRawSemantics(APFloatSemantics Sem) {
    FloatingLiteralBits.Semantics = Sem;
  }

  /// Return the APFloat semantics this literal uses.
  const llvm::fltSemantics &getSemantics() const;

  /// Set the APFloat semantics this literal uses.
  void setSemantics(const llvm::fltSemantics &Sem);

  bool isExact() const { return FloatingLiteralBits.IsExact; }
  void setExact(bool E) { FloatingLiteralBits.IsExact = E; }

  /// getValueAsApproximateDouble - This returns the value as an inaccurate
  /// double.  Note that this may cause loss of precision, but is useful for
  /// debugging dumps, etc.
  double getValueAsApproximateDouble() const;

  SourceLocation getLocation() const { return Loc; }
  void setLocation(SourceLocation L) { Loc = L; }

  SourceLocation getLocStart() const LLVM_READONLY { return Loc; }
  SourceLocation getLocEnd() const LLVM_READONLY { return Loc; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == FloatingLiteralClass;
  }

  // Iterators
  child_range children() { return child_range(); }
};

/// ImaginaryLiteral - We support imaginary integer and floating point literals,
/// like "1.0i".  We represent these as a wrapper around FloatingLiteral and
/// IntegerLiteral classes.  Instances of this class always have a Complex type
/// whose element type matches the subexpression.
///
class ImaginaryLiteral : public Expr {
  Stmt *Val;
public:
  ImaginaryLiteral(Expr *val, QualType Ty)
    : Expr(ImaginaryLiteralClass, Ty, VK_RValue, OK_Ordinary, false, false,
           false, false),
      Val(val) {}

  /// \brief Build an empty imaginary literal.
  explicit ImaginaryLiteral(EmptyShell Empty)
    : Expr(ImaginaryLiteralClass, Empty) { }

  const Expr *getSubExpr() const { return cast<Expr>(Val); }
  Expr *getSubExpr() { return cast<Expr>(Val); }
  void setSubExpr(Expr *E) { Val = E; }

  SourceLocation getLocStart() const LLVM_READONLY { return Val->getLocStart(); }
  SourceLocation getLocEnd() const LLVM_READONLY { return Val->getLocEnd(); }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == ImaginaryLiteralClass;
  }

  // Iterators
  child_range children() { return child_range(&Val, &Val+1); }
};

/// StringLiteral - This represents a string literal expression, e.g. "foo"
/// or L"bar" (wide strings).  The actual string is returned by getBytes()
/// is NOT null-terminated, and the length of the string is determined by
/// calling getByteLength().  The C type for a string is always a
/// ConstantArrayType.  In C++, the char type is const qualified, in C it is
/// not.
///
/// Note that strings in C can be formed by concatenation of multiple string
/// literal pptokens in translation phase #6.  This keeps track of the locations
/// of each of these pieces.
///
/// Strings in C can also be truncated and extended by assigning into arrays,
/// e.g. with constructs like:
///   char X[2] = "foobar";
/// In this case, getByteLength() will return 6, but the string literal will
/// have type "char[2]".
class StringLiteral : public Expr {
public:
  enum StringKind {
    Ascii,
    Wide,
    UTF8,
    UTF16,
    UTF32
  };

private:
  friend class ASTStmtReader;

  union {
    const char *asChar;
    const uint16_t *asUInt16;
    const uint32_t *asUInt32;
  } StrData;
  unsigned Length;
  unsigned CharByteWidth : 4;
  unsigned Kind : 3;
  unsigned IsPascal : 1;
  unsigned NumConcatenated;
  SourceLocation TokLocs[1];

  StringLiteral(QualType Ty) :
    Expr(StringLiteralClass, Ty, VK_LValue, OK_Ordinary, false, false, false,
         false) {}

  static int mapCharByteWidth(TargetInfo const &target,StringKind k);

public:
  /// This is the "fully general" constructor that allows representation of
  /// strings formed from multiple concatenated tokens.
  static StringLiteral *Create(const ASTContext &C, StringRef Str,
                               StringKind Kind, bool Pascal, QualType Ty,
                               const SourceLocation *Loc, unsigned NumStrs);

  /// Simple constructor for string literals made from one token.
  static StringLiteral *Create(const ASTContext &C, StringRef Str,
                               StringKind Kind, bool Pascal, QualType Ty,
                               SourceLocation Loc) {
    return Create(C, Str, Kind, Pascal, Ty, &Loc, 1);
  }

  /// \brief Construct an empty string literal.
  static StringLiteral *CreateEmpty(const ASTContext &C, unsigned NumStrs);

  StringRef getString() const {
    assert(CharByteWidth==1
           && "This function is used in places that assume strings use char");
    return StringRef(StrData.asChar, getByteLength());
  }

  /// Allow access to clients that need the byte representation, such as
  /// ASTWriterStmt::VisitStringLiteral().
  StringRef getBytes() const {
    // FIXME: StringRef may not be the right type to use as a result for this.
    if (CharByteWidth == 1)
      return StringRef(StrData.asChar, getByteLength());
    if (CharByteWidth == 4)
      return StringRef(reinterpret_cast<const char*>(StrData.asUInt32),
                       getByteLength());
    assert(CharByteWidth == 2 && "unsupported CharByteWidth");
    return StringRef(reinterpret_cast<const char*>(StrData.asUInt16),
                     getByteLength());
  }

  void outputString(raw_ostream &OS) const;

  uint32_t getCodeUnit(size_t i) const {
    assert(i < Length && "out of bounds access");
    if (CharByteWidth == 1)
      return static_cast<unsigned char>(StrData.asChar[i]);
    if (CharByteWidth == 4)
      return StrData.asUInt32[i];
    assert(CharByteWidth == 2 && "unsupported CharByteWidth");
    return StrData.asUInt16[i];
  }

  unsigned getByteLength() const { return CharByteWidth*Length; }
  unsigned getLength() const { return Length; }
  unsigned getCharByteWidth() const { return CharByteWidth; }

  /// \brief Sets the string data to the given string data.
  void setString(const ASTContext &C, StringRef Str,
                 StringKind Kind, bool IsPascal);

  StringKind getKind() const { return static_cast<StringKind>(Kind); }


  bool isAscii() const { return Kind == Ascii; }
  bool isWide() const { return Kind == Wide; }
  bool isUTF8() const { return Kind == UTF8; }
  bool isUTF16() const { return Kind == UTF16; }
  bool isUTF32() const { return Kind == UTF32; }
  bool isPascal() const { return IsPascal; }

  bool containsNonAsciiOrNull() const {
    StringRef Str = getString();
    for (unsigned i = 0, e = Str.size(); i != e; ++i)
      if (!isASCII(Str[i]) || !Str[i])
        return true;
    return false;
  }

  /// getNumConcatenated - Get the number of string literal tokens that were
  /// concatenated in translation phase #6 to form this string literal.
  unsigned getNumConcatenated() const { return NumConcatenated; }

  SourceLocation getStrTokenLoc(unsigned TokNum) const {
    assert(TokNum < NumConcatenated && "Invalid tok number");
    return TokLocs[TokNum];
  }
  void setStrTokenLoc(unsigned TokNum, SourceLocation L) {
    assert(TokNum < NumConcatenated && "Invalid tok number");
    TokLocs[TokNum] = L;
  }

  /// getLocationOfByte - Return a source location that points to the specified
  /// byte of this string literal.
  ///
  /// Strings are amazingly complex.  They can be formed from multiple tokens
  /// and can have escape sequences in them in addition to the usual trigraph
  /// and escaped newline business.  This routine handles this complexity.
  ///
  SourceLocation getLocationOfByte(unsigned ByteNo, const SourceManager &SM,
                                   const LangOptions &Features,
                                   const TargetInfo &Target) const;

  typedef const SourceLocation *tokloc_iterator;
  tokloc_iterator tokloc_begin() const { return TokLocs; }
  tokloc_iterator tokloc_end() const { return TokLocs+NumConcatenated; }

  SourceLocation getLocStart() const LLVM_READONLY { return TokLocs[0]; }
  SourceLocation getLocEnd() const LLVM_READONLY {
    return TokLocs[NumConcatenated - 1];
  }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == StringLiteralClass;
  }

  // Iterators
  child_range children() { return child_range(); }
};

/// ParenExpr - This represents a parethesized expression, e.g. "(1)".  This
/// AST node is only formed if full location information is requested.
class ParenExpr : public Expr {
  SourceLocation L, R;
  Stmt *Val;
public:
  ParenExpr(SourceLocation l, SourceLocation r, Expr *val)
    : Expr(ParenExprClass, val->getType(),
           val->getValueKind(), val->getObjectKind(),
           val->isTypeDependent(), val->isValueDependent(),
           val->isInstantiationDependent(),
           val->containsUnexpandedParameterPack()),
      L(l), R(r), Val(val) {}

  /// \brief Construct an empty parenthesized expression.
  explicit ParenExpr(EmptyShell Empty)
    : Expr(ParenExprClass, Empty) { }

  const Expr *getSubExpr() const { return cast<Expr>(Val); }
  Expr *getSubExpr() { return cast<Expr>(Val); }
  void setSubExpr(Expr *E) { Val = E; }

  SourceLocation getLocStart() const LLVM_READONLY { return L; }
  SourceLocation getLocEnd() const LLVM_READONLY { return R; }

  /// \brief Get the location of the left parentheses '('.
  SourceLocation getLParen() const { return L; }
  void setLParen(SourceLocation Loc) { L = Loc; }

  /// \brief Get the location of the right parentheses ')'.
  SourceLocation getRParen() const { return R; }
  void setRParen(SourceLocation Loc) { R = Loc; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == ParenExprClass;
  }

  // Iterators
  child_range children() { return child_range(&Val, &Val+1); }
};


/// UnaryOperator - This represents the unary-expression's (except sizeof and
/// alignof), the postinc/postdec operators from postfix-expression, and various
/// extensions.
///
/// Notes on various nodes:
///
/// Real/Imag - These return the real/imag part of a complex operand.  If
///   applied to a non-complex value, the former returns its operand and the
///   later returns zero in the type of the operand.
///
class UnaryOperator : public Expr {
public:
  typedef UnaryOperatorKind Opcode;

private:
  unsigned Opc : 5;
  SourceLocation Loc;
  Stmt *Val;
public:

  UnaryOperator(Expr *input, Opcode opc, QualType type,
                ExprValueKind VK, ExprObjectKind OK, SourceLocation l)
    : Expr(UnaryOperatorClass, type, VK, OK,
           input->isTypeDependent() || type->isDependentType(),
           input->isValueDependent(),
           (input->isInstantiationDependent() ||
            type->isInstantiationDependentType()),
           input->containsUnexpandedParameterPack()),
      Opc(opc), Loc(l), Val(input) {}

  /// \brief Build an empty unary operator.
  explicit UnaryOperator(EmptyShell Empty)
    : Expr(UnaryOperatorClass, Empty), Opc(UO_AddrOf) { }

  Opcode getOpcode() const { return static_cast<Opcode>(Opc); }
  void setOpcode(Opcode O) { Opc = O; }

  Expr *getSubExpr() const { return cast<Expr>(Val); }
  void setSubExpr(Expr *E) { Val = E; }

  /// getOperatorLoc - Return the location of the operator.
  SourceLocation getOperatorLoc() const { return Loc; }
  void setOperatorLoc(SourceLocation L) { Loc = L; }

  /// isPostfix - Return true if this is a postfix operation, like x++.
  static bool isPostfix(Opcode Op) {
    return Op == UO_PostInc || Op == UO_PostDec;
  }

  /// isPrefix - Return true if this is a prefix operation, like --x.
  static bool isPrefix(Opcode Op) {
    return Op == UO_PreInc || Op == UO_PreDec;
  }

  bool isPrefix() const { return isPrefix(getOpcode()); }
  bool isPostfix() const { return isPostfix(getOpcode()); }

  static bool isIncrementOp(Opcode Op) {
    return Op == UO_PreInc || Op == UO_PostInc;
  }
  bool isIncrementOp() const {
    return isIncrementOp(getOpcode());
  }

  static bool isDecrementOp(Opcode Op) {
    return Op == UO_PreDec || Op == UO_PostDec;
  }
  bool isDecrementOp() const {
    return isDecrementOp(getOpcode());
  }

  static bool isIncrementDecrementOp(Opcode Op) { return Op <= UO_PreDec; }
  bool isIncrementDecrementOp() const {
    return isIncrementDecrementOp(getOpcode());
  }

  static bool isArithmeticOp(Opcode Op) {
    return Op >= UO_Plus && Op <= UO_LNot;
  }
  bool isArithmeticOp() const { return isArithmeticOp(getOpcode()); }

  /// getOpcodeStr - Turn an Opcode enum value into the punctuation char it
  /// corresponds to, e.g. "sizeof" or "[pre]++"
  static StringRef getOpcodeStr(Opcode Op);

  /// \brief Retrieve the unary opcode that corresponds to the given
  /// overloaded operator.
  static Opcode getOverloadedOpcode(OverloadedOperatorKind OO, bool Postfix);

  /// \brief Retrieve the overloaded operator kind that corresponds to
  /// the given unary opcode.
  static OverloadedOperatorKind getOverloadedOperator(Opcode Opc);

  SourceLocation getLocStart() const LLVM_READONLY {
    return isPostfix() ? Val->getLocStart() : Loc;
  }
  SourceLocation getLocEnd() const LLVM_READONLY {
    return isPostfix() ? Loc : Val->getLocEnd();
  }
  SourceLocation getExprLoc() const LLVM_READONLY { return Loc; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == UnaryOperatorClass;
  }

  // Iterators
  child_range children() { return child_range(&Val, &Val+1); }
};

/// OffsetOfExpr - [C99 7.17] - This represents an expression of the form
/// offsetof(record-type, member-designator). For example, given:
/// @code
/// struct S {
///   float f;
///   double d;
/// };
/// struct T {
///   int i;
///   struct S s[10];
/// };
/// @endcode
/// we can represent and evaluate the expression @c offsetof(struct T, s[2].d).

class OffsetOfExpr : public Expr {
public:
  // __builtin_offsetof(type, identifier(.identifier|[expr])*)
  class OffsetOfNode {
  public:
    /// \brief The kind of offsetof node we have.
    enum Kind {
      /// \brief An index into an array.
      Array = 0x00,
      /// \brief A field.
      Field = 0x01,
      /// \brief A field in a dependent type, known only by its name.
      Identifier = 0x02,
      /// \brief An implicit indirection through a C++ base class, when the
      /// field found is in a base class.
      Base = 0x03
    };

  private:
    enum { MaskBits = 2, Mask = 0x03 };

    /// \brief The source range that covers this part of the designator.
    SourceRange Range;

    /// \brief The data describing the designator, which comes in three
    /// different forms, depending on the lower two bits.
    ///   - An unsigned index into the array of Expr*'s stored after this node
    ///     in memory, for [constant-expression] designators.
    ///   - A FieldDecl*, for references to a known field.
    ///   - An IdentifierInfo*, for references to a field with a given name
    ///     when the class type is dependent.
    ///   - A CXXBaseSpecifier*, for references that look at a field in a
    ///     base class.
    uintptr_t Data;

  public:
    /// \brief Create an offsetof node that refers to an array element.
    OffsetOfNode(SourceLocation LBracketLoc, unsigned Index,
                 SourceLocation RBracketLoc)
      : Range(LBracketLoc, RBracketLoc), Data((Index << 2) | Array) { }

    /// \brief Create an offsetof node that refers to a field.
    OffsetOfNode(SourceLocation DotLoc, FieldDecl *Field,
                 SourceLocation NameLoc)
      : Range(DotLoc.isValid()? DotLoc : NameLoc, NameLoc),
        Data(reinterpret_cast<uintptr_t>(Field) | OffsetOfNode::Field) { }

    /// \brief Create an offsetof node that refers to an identifier.
    OffsetOfNode(SourceLocation DotLoc, IdentifierInfo *Name,
                 SourceLocation NameLoc)
      : Range(DotLoc.isValid()? DotLoc : NameLoc, NameLoc),
        Data(reinterpret_cast<uintptr_t>(Name) | Identifier) { }

    /// \brief Create an offsetof node that refers into a C++ base class.
    explicit OffsetOfNode(const CXXBaseSpecifier *Base)
      : Range(), Data(reinterpret_cast<uintptr_t>(Base) | OffsetOfNode::Base) {}

    /// \brief Determine what kind of offsetof node this is.
    Kind getKind() const {
      return static_cast<Kind>(Data & Mask);
    }

    /// \brief For an array element node, returns the index into the array
    /// of expressions.
    unsigned getArrayExprIndex() const {
      assert(getKind() == Array);
      return Data >> 2;
    }

    /// \brief For a field offsetof node, returns the field.
    FieldDecl *getField() const {
      assert(getKind() == Field);
      return reinterpret_cast<FieldDecl *>(Data & ~(uintptr_t)Mask);
    }

    /// \brief For a field or identifier offsetof node, returns the name of
    /// the field.
    IdentifierInfo *getFieldName() const;

    /// \brief For a base class node, returns the base specifier.
    CXXBaseSpecifier *getBase() const {
      assert(getKind() == Base);
      return reinterpret_cast<CXXBaseSpecifier *>(Data & ~(uintptr_t)Mask);
    }

    /// \brief Retrieve the source range that covers this offsetof node.
    ///
    /// For an array element node, the source range contains the locations of
    /// the square brackets. For a field or identifier node, the source range
    /// contains the location of the period (if there is one) and the
    /// identifier.
    SourceRange getSourceRange() const LLVM_READONLY { return Range; }
    SourceLocation getLocStart() const LLVM_READONLY { return Range.getBegin(); }
    SourceLocation getLocEnd() const LLVM_READONLY { return Range.getEnd(); }
  };

private:

  SourceLocation OperatorLoc, RParenLoc;
  // Base type;
  TypeSourceInfo *TSInfo;
  // Number of sub-components (i.e. instances of OffsetOfNode).
  unsigned NumComps;
  // Number of sub-expressions (i.e. array subscript expressions).
  unsigned NumExprs;

  OffsetOfExpr(const ASTContext &C, QualType type,
               SourceLocation OperatorLoc, TypeSourceInfo *tsi,
               ArrayRef<OffsetOfNode> comps, ArrayRef<Expr*> exprs,
               SourceLocation RParenLoc);

  explicit OffsetOfExpr(unsigned numComps, unsigned numExprs)
    : Expr(OffsetOfExprClass, EmptyShell()),
      TSInfo(nullptr), NumComps(numComps), NumExprs(numExprs) {}

public:

  static OffsetOfExpr *Create(const ASTContext &C, QualType type,
                              SourceLocation OperatorLoc, TypeSourceInfo *tsi,
                              ArrayRef<OffsetOfNode> comps,
                              ArrayRef<Expr*> exprs, SourceLocation RParenLoc);

  static OffsetOfExpr *CreateEmpty(const ASTContext &C,
                                   unsigned NumComps, unsigned NumExprs);

  /// getOperatorLoc - Return the location of the operator.
  SourceLocation getOperatorLoc() const { return OperatorLoc; }
  void setOperatorLoc(SourceLocation L) { OperatorLoc = L; }

  /// \brief Return the location of the right parentheses.
  SourceLocation getRParenLoc() const { return RParenLoc; }
  void setRParenLoc(SourceLocation R) { RParenLoc = R; }

  TypeSourceInfo *getTypeSourceInfo() const {
    return TSInfo;
  }
  void setTypeSourceInfo(TypeSourceInfo *tsi) {
    TSInfo = tsi;
  }

  const OffsetOfNode &getComponent(unsigned Idx) const {
    assert(Idx < NumComps && "Subscript out of range");
    return reinterpret_cast<const OffsetOfNode *> (this + 1)[Idx];
  }

  void setComponent(unsigned Idx, OffsetOfNode ON) {
    assert(Idx < NumComps && "Subscript out of range");
    reinterpret_cast<OffsetOfNode *> (this + 1)[Idx] = ON;
  }

  unsigned getNumComponents() const {
    return NumComps;
  }

  Expr* getIndexExpr(unsigned Idx) {
    assert(Idx < NumExprs && "Subscript out of range");
    return reinterpret_cast<Expr **>(
                    reinterpret_cast<OffsetOfNode *>(this+1) + NumComps)[Idx];
  }
  const Expr *getIndexExpr(unsigned Idx) const {
    return const_cast<OffsetOfExpr*>(this)->getIndexExpr(Idx);
  }

  void setIndexExpr(unsigned Idx, Expr* E) {
    assert(Idx < NumComps && "Subscript out of range");
    reinterpret_cast<Expr **>(
                reinterpret_cast<OffsetOfNode *>(this+1) + NumComps)[Idx] = E;
  }

  unsigned getNumExpressions() const {
    return NumExprs;
  }

  SourceLocation getLocStart() const LLVM_READONLY { return OperatorLoc; }
  SourceLocation getLocEnd() const LLVM_READONLY { return RParenLoc; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == OffsetOfExprClass;
  }

  // Iterators
  child_range children() {
    Stmt **begin =
      reinterpret_cast<Stmt**>(reinterpret_cast<OffsetOfNode*>(this + 1)
                               + NumComps);
    return child_range(begin, begin + NumExprs);
  }
};

/// UnaryExprOrTypeTraitExpr - expression with either a type or (unevaluated)
/// expression operand.  Used for sizeof/alignof (C99 6.5.3.4) and
/// vec_step (OpenCL 1.1 6.11.12).
class UnaryExprOrTypeTraitExpr : public Expr {
  union {
    TypeSourceInfo *Ty;
    Stmt *Ex;
  } Argument;
  SourceLocation OpLoc, RParenLoc;

public:
  UnaryExprOrTypeTraitExpr(UnaryExprOrTypeTrait ExprKind, TypeSourceInfo *TInfo,
                           QualType resultType, SourceLocation op,
                           SourceLocation rp) :
      Expr(UnaryExprOrTypeTraitExprClass, resultType, VK_RValue, OK_Ordinary,
           false, // Never type-dependent (C++ [temp.dep.expr]p3).
           // Value-dependent if the argument is type-dependent.
           TInfo->getType()->isDependentType(),
           TInfo->getType()->isInstantiationDependentType(),
           TInfo->getType()->containsUnexpandedParameterPack()),
      OpLoc(op), RParenLoc(rp) {
    UnaryExprOrTypeTraitExprBits.Kind = ExprKind;
    UnaryExprOrTypeTraitExprBits.IsType = true;
    Argument.Ty = TInfo;
  }

  UnaryExprOrTypeTraitExpr(UnaryExprOrTypeTrait ExprKind, Expr *E,
                           QualType resultType, SourceLocation op,
                           SourceLocation rp) :
      Expr(UnaryExprOrTypeTraitExprClass, resultType, VK_RValue, OK_Ordinary,
           false, // Never type-dependent (C++ [temp.dep.expr]p3).
           // Value-dependent if the argument is type-dependent.
           E->isTypeDependent(),
           E->isInstantiationDependent(),
           E->containsUnexpandedParameterPack()),
      OpLoc(op), RParenLoc(rp) {
    UnaryExprOrTypeTraitExprBits.Kind = ExprKind;
    UnaryExprOrTypeTraitExprBits.IsType = false;
    Argument.Ex = E;
  }

  /// \brief Construct an empty sizeof/alignof expression.
  explicit UnaryExprOrTypeTraitExpr(EmptyShell Empty)
    : Expr(UnaryExprOrTypeTraitExprClass, Empty) { }

  UnaryExprOrTypeTrait getKind() const {
    return static_cast<UnaryExprOrTypeTrait>(UnaryExprOrTypeTraitExprBits.Kind);
  }
  void setKind(UnaryExprOrTypeTrait K) { UnaryExprOrTypeTraitExprBits.Kind = K;}

  bool isArgumentType() const { return UnaryExprOrTypeTraitExprBits.IsType; }
  QualType getArgumentType() const {
    return getArgumentTypeInfo()->getType();
  }
  TypeSourceInfo *getArgumentTypeInfo() const {
    assert(isArgumentType() && "calling getArgumentType() when arg is expr");
    return Argument.Ty;
  }
  Expr *getArgumentExpr() {
    assert(!isArgumentType() && "calling getArgumentExpr() when arg is type");
    return static_cast<Expr*>(Argument.Ex);
  }
  const Expr *getArgumentExpr() const {
    return const_cast<UnaryExprOrTypeTraitExpr*>(this)->getArgumentExpr();
  }

  void setArgument(Expr *E) {
    Argument.Ex = E;
    UnaryExprOrTypeTraitExprBits.IsType = false;
  }
  void setArgument(TypeSourceInfo *TInfo) {
    Argument.Ty = TInfo;
    UnaryExprOrTypeTraitExprBits.IsType = true;
  }

  /// Gets the argument type, or the type of the argument expression, whichever
  /// is appropriate.
  QualType getTypeOfArgument() const {
    return isArgumentType() ? getArgumentType() : getArgumentExpr()->getType();
  }

  SourceLocation getOperatorLoc() const { return OpLoc; }
  void setOperatorLoc(SourceLocation L) { OpLoc = L; }

  SourceLocation getRParenLoc() const { return RParenLoc; }
  void setRParenLoc(SourceLocation L) { RParenLoc = L; }

  SourceLocation getLocStart() const LLVM_READONLY { return OpLoc; }
  SourceLocation getLocEnd() const LLVM_READONLY { return RParenLoc; }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == UnaryExprOrTypeTraitExprClass;
  }

  // Iterators
  child_range children();
};

//===----------------------------------------------------------------------===//
// Postfix Operators.
//===----------------------------------------------------------------------===//

/// ArraySubscriptExpr - [C99 6.5.2.1] Array Subscripting.
class ArraySubscriptExpr : public Expr {
  enum { LHS, RHS, END_EXPR=2 };
  Stmt* SubExprs[END_EXPR];
  SourceLocation RBracketLoc;
public:
  ArraySubscriptExpr(Expr *lhs, Expr *rhs, QualType t,
                     ExprValueKind VK, ExprObjectKind OK,
                     SourceLocation rbracketloc)
  : Expr(ArraySubscriptExprClass, t, VK, OK,
         lhs->isTypeDependent() || rhs->isTypeDependent(),
         lhs->isValueDependent() || rhs->isValueDependent(),
         (lhs->isInstantiationDependent() ||
          rhs->isInstantiationDependent()),
         (lhs->containsUnexpandedParameterPack() ||
          rhs->containsUnexpandedParameterPack())),
    RBracketLoc(rbracketloc) {
    SubExprs[LHS] = lhs;
    SubExprs[RHS] = rhs;
  }

  /// \brief Create an empty array subscript expression.
  explicit ArraySubscriptExpr(EmptyShell Shell)
    : Expr(ArraySubscriptExprClass, Shell) { }

  /// An array access can be written A[4] or 4[A] (both are equivalent).
  /// - getBase() and getIdx() always present the normalized view: A[4].
  ///    In this case getBase() returns "A" and getIdx() returns "4".
  /// - getLHS() and getRHS() present the syntactic view. e.g. for
  ///    4[A] getLHS() returns "4".
  /// Note: Because vector element access is also written A[4] we must
  /// predicate the format conversion in getBase and getIdx only on the
  /// the type of the RHS, as it is possible for the LHS to be a vector of
  /// integer type
  Expr *getLHS() { return cast<Expr>(SubExprs[LHS]); }
  const Expr *getLHS() const { return cast<Expr>(SubExprs[LHS]); }
  void setLHS(Expr *E) { SubExprs[LHS] = E; }

  Expr *getRHS() { return cast<Expr>(SubExprs[RHS]); }
  const Expr *getRHS() const { return cast<Expr>(SubExprs[RHS]); }
  void setRHS(Expr *E) { SubExprs[RHS] = E; }

  Expr *getBase() {
    return cast<Expr>(getRHS()->getType()->isIntegerType() ? getLHS():getRHS());
  }

  const Expr *getBase() const {
    return cast<Expr>(getRHS()->getType()->isIntegerType() ? getLHS():getRHS());
  }

  Expr *getIdx() {
    return cast<Expr>(getRHS()->getType()->isIntegerType() ? getRHS():getLHS());
  }

  const Expr *getIdx() const {
    return cast<Expr>(getRHS()->getType()->isIntegerType() ? getRHS():getLHS());
  }

  SourceLocation getLocStart() const LLVM_READONLY {
    return getLHS()->getLocStart();
  }
  SourceLocation getLocEnd() const LLVM_READONLY { return RBracketLoc; }

  SourceLocation getRBracketLoc() const { return RBracketLoc; }
  void setRBracketLoc(SourceLocation L) { RBracketLoc = L; }

  SourceLocation getExprLoc() const LLVM_READONLY {
    return getBase()->getExprLoc();
  }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == ArraySubscriptExprClass;
  }

  // Iterators
  child_range children() {
    return child_range(&SubExprs[0], &SubExprs[0]+END_EXPR);
  }
};


/// CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
/// CallExpr itself represents a normal function call, e.g., "f(x, 2)",
/// while its subclasses may represent alternative syntax that (semantically)
/// results in a function call. For example, CXXOperatorCallExpr is
/// a subclass for overloaded operator calls that use operator syntax, e.g.,
/// "str1 + str2" to resolve to a function call.
class CallExpr : public Expr {
  enum { FN=0, PREARGS_START=1 };
  Stmt **SubExprs;
  unsigned NumArgs;
  SourceLocation RParenLoc;

protected:
  // These versions of the constructor are for derived classes.
  CallExpr(const ASTContext& C, StmtClass SC, Expr *fn, unsigned NumPreArgs,
           ArrayRef<Expr*> args, QualType t, ExprValueKind VK,
           SourceLocation rparenloc);
  CallExpr(const ASTContext &C, StmtClass SC, unsigned NumPreArgs,
           EmptyShell Empty);

  Stmt *getPreArg(unsigned i) {
    assert(i < getNumPreArgs() && "Prearg access out of range!");
    return SubExprs[PREARGS_START+i];
  }
  const Stmt *getPreArg(unsigned i) const {
    assert(i < getNumPreArgs() && "Prearg access out of range!");
    return SubExprs[PREARGS_START+i];
  }
  void setPreArg(unsigned i, Stmt *PreArg) {
    assert(i < getNumPreArgs() && "Prearg access out of range!");
    SubExprs[PREARGS_START+i] = PreArg;
  }

  unsigned getNumPreArgs() const { return CallExprBits.NumPreArgs; }

public:
  CallExpr(const ASTContext& C, Expr *fn, ArrayRef<Expr*> args, QualType t,
           ExprValueKind VK, SourceLocation rparenloc);

  /// \brief Build an empty call expression.
  CallExpr(const ASTContext &C, StmtClass SC, EmptyShell Empty);

  const Expr *getCallee() const { return cast<Expr>(SubExprs[FN]); }
  Expr *getCallee() { return cast<Expr>(SubExprs[FN]); }
  void setCallee(Expr *F) { SubExprs[FN] = F; }

  Decl *getCalleeDecl();
  const Decl *getCalleeDecl() const {
    return const_cast<CallExpr*>(this)->getCalleeDecl();
  }

  /// \brief If the callee is a FunctionDecl, return it. Otherwise return 0.
  FunctionDecl *getDirectCallee();
  const FunctionDecl *getDirectCallee() const {
    return const_cast<CallExpr*>(this)->getDirectCallee();
  }

  /// getNumArgs - Return the number of actual arguments to this call.
  ///
  unsigned getNumArgs() const { return NumArgs; }

  /// \brief Retrieve the call arguments.
  Expr **getArgs() {
    return reinterpret_cast<Expr **>(SubExprs+getNumPreArgs()+PREARGS_START);
  }
  const Expr *const *getArgs() const {
    return const_cast<CallExpr*>(this)->getArgs();
  }

  /// getArg - Return the specified argument.
  Expr *getArg(unsigned Arg) {
    assert(Arg < NumArgs && "Arg access out of range!");
    return cast<Expr>(SubExprs[Arg+getNumPreArgs()+PREARGS_START]);
  }
  const Expr *getArg(unsigned Arg) const {
    assert(Arg < NumArgs && "Arg access out of range!");
    return cast<Expr>(SubExprs[Arg+getNumPreArgs()+PREARGS_START]);
  }

  /// setArg - Set the specified argument.
  void setArg(unsigned Arg, Expr *ArgExpr) {
    assert(Arg < NumArgs && "Arg access out of range!");
    SubExprs[Arg+getNumPreArgs()+PREARGS_START] = ArgExpr;
  }

  /// setNumArgs - This changes the number of arguments present in this call.
  /// Any orphaned expressions are deleted by this, and any new operands are set
  /// to null.
  void setNumArgs(const ASTContext& C, unsigned NumArgs);

  typedef ExprIterator arg_iterator;
  typedef ConstExprIterator const_arg_iterator;
  typedef llvm::iterator_range<arg_iterator> arg_range;
  typedef llvm::iterator_range<const_arg_iterator> arg_const_range;

  arg_range arguments() { return arg_range(arg_begin(), arg_end()); }
  arg_const_range arguments() const {
    return arg_const_range(arg_begin(), arg_end());
  }

  arg_iterator arg_begin() { return SubExprs+PREARGS_START+getNumPreArgs(); }
  arg_iterator arg_end() {
    return SubExprs+PREARGS_START+getNumPreArgs()+getNumArgs();
  }
  const_arg_iterator arg_begin() const {
    return SubExprs+PREARGS_START+getNumPreArgs();
  }
  const_arg_iterator arg_end() const {
    return SubExprs+PREARGS_START+getNumPreArgs()+getNumArgs();
  }

  /// This method provides fast access to all the subexpressions of
  /// a CallExpr without going through the slower virtual child_iterator
  /// interface.  This provides efficient reverse iteration of the
  /// subexpressions.  This is currently used for CFG construction.
  ArrayRef<Stmt*> getRawSubExprs() {
    return ArrayRef<Stmt*>(SubExprs,
                           getNumPreArgs() + PREARGS_START + getNumArgs());
  }

  /// getNumCommas - Return the number of commas that must have been present in
  /// this function call.
  unsigned getNumCommas() const { return NumArgs ? NumArgs - 1 : 0; }

  /// getBuiltinCallee - If this is a call to a builtin, return the builtin ID
  /// of the callee. If not, return 0.
  unsigned getBuiltinCallee() const;

  /// \brief Returns \c true if this is a call to a builtin which does not
  /// evaluate side-effects within its arguments.
  bool isUnevaluatedBuiltinCall(ASTContext &Ctx) const;

  /// getCallReturnType - Get the return type of the call expr. This is not
  /// always the type of the expr itself, if the return type is a reference
  /// type.
  QualType getCallReturnType() const;

  SourceLocation getRParenLoc() const { return RParenLoc; }
  void setRParenLoc(SourceLocation L) { RParenLoc = L; }

  SourceLocation getLocStart() const LLVM_READONLY;
  SourceLocation getLocEnd() const LLVM_READONLY;

  static bool classof(const Stmt *T) {
    return T->getStmtClass() >= firstCallExprConstant &&
           T->getStmtClass() <= lastCallExprConstant;
  }

  // Iterators
  child_range children() {
    return child_range(&SubExprs[0],
                       &SubExprs[0]+NumArgs+getNumPreArgs()+PREARGS_START);
  }
};

/// MemberExpr - [C99 6.5.2.3] Structure and Union Members.  X->F and X.F.
///
class MemberExpr : public Expr {
  /// Extra data stored in some member expressions.
  struct MemberNameQualifier {
    /// \brief The nested-name-specifier that qualifies the name, including
    /// source-location information.
    NestedNameSpecifierLoc QualifierLoc;

    /// \brief The DeclAccessPair through which the MemberDecl was found due to
    /// name qualifiers.
    DeclAccessPair FoundDecl;
  };

  /// Base - the expression for the base pointer or structure references.  In
  /// X.F, this is "X".
  Stmt *Base;

  /// MemberDecl - This is the decl being referenced by the field/member name.
  /// In X.F, this is the decl referenced by F.
  ValueDecl *MemberDecl;

  /// MemberDNLoc - Provides source/type location info for the
  /// declaration name embedded in MemberDecl.
  DeclarationNameLoc MemberDNLoc;

  /// MemberLoc - This is the location of the member name.
  SourceLocation MemberLoc;

  /// IsArrow - True if this is "X->F", false if this is "X.F".
  bool IsArrow : 1;

  /// \brief True if this member expression used a nested-name-specifier to
  /// refer to the member, e.g., "x->Base::f", or found its member via a using
  /// declaration.  When true, a MemberNameQualifier
  /// structure is allocated immediately after the MemberExpr.
  bool HasQualifierOrFoundDecl : 1;

  /// \brief True if this member expression specified a template keyword
  /// and/or a template argument list explicitly, e.g., x->f<int>,
  /// x->template f, x->template f<int>.
  /// When true, an ASTTemplateKWAndArgsInfo structure and its
  /// TemplateArguments (if any) are allocated immediately after
  /// the MemberExpr or, if the member expression also has a qualifier,
  /// after the MemberNameQualifier structure.
  bool HasTemplateKWAndArgsInfo : 1;

  /// \brief True if this member expression refers to a method that
  /// was resolved from an overloaded set having size greater than 1.
  bool HadMultipleCandidates : 1;

  /// \brief Retrieve the qualifier that preceded the member name, if any.
  MemberNameQualifier *getMemberQualifier() {
    assert(HasQualifierOrFoundDecl);
    return reinterpret_cast<MemberNameQualifier *> (this + 1);
  }

  /// \brief Retrieve the qualifier that preceded the member name, if any.
  const MemberNameQualifier *getMemberQualifier() const {
    return const_cast<MemberExpr *>(this)->getMemberQualifier();
  }

public:
  MemberExpr(Expr *base, bool isarrow, ValueDecl *memberdecl,
             const DeclarationNameInfo &NameInfo, QualType ty,
             ExprValueKind VK, ExprObjectKind OK)
    : Expr(MemberExprClass, ty, VK, OK,
           base->isTypeDependent(),
           base->isValueDependent(),
           base->isInstantiationDependent(),
           base->containsUnexpandedParameterPack()),
      Base(base), MemberDecl(memberdecl), MemberDNLoc(NameInfo.getInfo()),
      MemberLoc(NameInfo.getLoc()), IsArrow(isarrow),
      HasQualifierOrFoundDecl(false), HasTemplateKWAndArgsInfo(false),
      HadMultipleCandidates(false) {
    assert(memberdecl->getDeclName() == NameInfo.getName());
  }

  // NOTE: this constructor should be used only when it is known that
  // the member name can not provide additional syntactic info
  // (i.e., source locations for C++ operator names or type source info
  // for constructors, destructors and conversion operators).
  MemberExpr(Expr *base, bool isarrow, ValueDecl *memberdecl,
             SourceLocation l, QualType ty,
             ExprValueKind VK, ExprObjectKind OK)
    : Expr(MemberExprClass, ty, VK, OK,
           base->isTypeDependent(), base->isValueDependent(),
           base->isInstantiationDependent(),
           base->containsUnexpandedParameterPack()),
      Base(base), MemberDecl(memberdecl), MemberDNLoc(), MemberLoc(l),
      IsArrow(isarrow),
      HasQualifierOrFoundDecl(false), HasTemplateKWAndArgsInfo(false),
      HadMultipleCandidates(false) {}

  static MemberExpr *Create(const ASTContext &C, Expr *base, bool isarrow,
                            NestedNameSpecifierLoc QualifierLoc,
                            SourceLocation TemplateKWLoc,
                            ValueDecl *memberdecl, DeclAccessPair founddecl,
                            DeclarationNameInfo MemberNameInfo,
                            const TemplateArgumentListInfo *targs,
                            QualType ty, ExprValueKind VK, ExprObjectKind OK);

  void setBase(Expr *E) { Base = E; }
  Expr *getBase() const { return cast<Expr>(Base); }

  /// \brief Retrieve the member declaration to which this expression refers.
  ///
  /// The returned declaration will either be a FieldDecl or (in C++)
  /// a CXXMethodDecl.
  ValueDecl *getMemberDecl() const { return MemberDecl; }
  void setMemberDecl(ValueDecl *D) { MemberDecl = D; }

  /// \brief Retrieves the declaration found by lookup.
  DeclAccessPair getFoundDecl() const {
    if (!HasQualifierOrFoundDecl)
      return DeclAccessPair::make(getMemberDecl(),
                                  getMemberDecl()->getAccess());
    return getMemberQualifier()->FoundDecl;
  }

  /// \brief Determines whether this member expression actually had
  /// a C++ nested-name-specifier prior to the name of the member, e.g.,
  /// x->Base::foo.
  bool hasQualifier() const { return getQualifier() != nullptr; }

  /// \brief If the member name was qualified, retrieves the
  /// nested-name-specifier that precedes the member name. Otherwise, returns
  /// NULL.
  NestedNameSpecifier *getQualifier() const {
    if (!HasQualifierOrFoundDecl)
      return nullptr;

    return getMemberQualifier()->QualifierLoc.getNestedNameSpecifier();
  }

  /// \brief If the member name was qualified, retrieves the
  /// nested-name-specifier that precedes the member name, with source-location
  /// information.
  NestedNameSpecifierLoc getQualifierLoc() const {
    if (!hasQualifier())
      return NestedNameSpecifierLoc();

    return getMemberQualifier()->QualifierLoc;
  }

  /// \brief Return the optional template keyword and arguments info.
  ASTTemplateKWAndArgsInfo *getTemplateKWAndArgsInfo() {
    if (!HasTemplateKWAndArgsInfo)
      return nullptr;

    if (!HasQualifierOrFoundDecl)
      return reinterpret_cast<ASTTemplateKWAndArgsInfo *>(this + 1);

    return reinterpret_cast<ASTTemplateKWAndArgsInfo *>(
                                                      getMemberQualifier() + 1);
  }

  /// \brief Return the optional template keyword and arguments info.
  const ASTTemplateKWAndArgsInfo *getTemplateKWAndArgsInfo() const {
    return const_cast<MemberExpr*>(this)->getTemplateKWAndArgsInfo();
  }

  /// \brief Retrieve the location of the template keyword preceding
  /// the member name, if any.
  SourceLocation getTemplateKeywordLoc() const {
    if (!HasTemplateKWAndArgsInfo) return SourceLocation();
    return getTemplateKWAndArgsInfo()->getTemplateKeywordLoc();
  }

  /// \brief Retrieve the location of the left angle bracket starting the
  /// explicit template argument list following the member name, if any.
  SourceLocation getLAngleLoc() const {
    if (!HasTemplateKWAndArgsInfo) return SourceLocation();
    return getTemplateKWAndArgsInfo()->LAngleLoc;
  }

  /// \brief Retrieve the location of the right angle bracket ending the
  /// explicit template argument list following the member name, if any.
  SourceLocation getRAngleLoc() const {
    if (!HasTemplateKWAndArgsInfo) return SourceLocation();
    return getTemplateKWAndArgsInfo()->RAngleLoc;
  }

  /// Determines whether the member name was preceded by the template keyword.
  bool hasTemplateKeyword() const { return getTemplateKeywordLoc().isValid(); }

  /// \brief Determines whether the member name was followed by an
  /// explicit template argument list.
  bool hasExplicitTemplateArgs() const { return getLAngleLoc().isValid(); }

  /// \brief Copies the template arguments (if present) into the given
  /// structure.
  void copyTemplateArgumentsInto(TemplateArgumentListInfo &List) const {
    if (hasExplicitTemplateArgs())
      getExplicitTemplateArgs().copyInto(List);
  }

  /// \brief Retrieve the explicit template argument list that
  /// follow the member template name.  This must only be called on an
  /// expression with explicit template arguments.
  ASTTemplateArgumentListInfo &getExplicitTemplateArgs() {
    assert(hasExplicitTemplateArgs());
    return *getTemplateKWAndArgsInfo();
  }

  /// \brief Retrieve the explicit template argument list that
  /// followed the member template name.  This must only be called on
  /// an expression with explicit template arguments.
  const ASTTemplateArgumentListInfo &getExplicitTemplateArgs() const {
    return const_cast<MemberExpr *>(this)->getExplicitTemplateArgs();
  }

  /// \brief Retrieves the optional explicit template arguments.
  /// This points to the same data as getExplicitTemplateArgs(), but
  /// returns null if there are no explicit template arguments.
  const ASTTemplateArgumentListInfo *getOptionalExplicitTemplateArgs() const {
    if (!hasExplicitTemplateArgs()) return nullptr;
    return &getExplicitTemplateArgs();
  }

  /// \brief Retrieve the template arguments provided as part of this
  /// template-id.
  const TemplateArgumentLoc *getTemplateArgs() const {
    if (!hasExplicitTemplateArgs())
      return nullptr;

    return getExplicitTemplateArgs().getTemplateArgs();
  }

  /// \brief Retrieve the number of template arguments provided as part of this
  /// template-id.
  unsigned getNumTemplateArgs() const {
    if (!hasExplicitTemplateArgs())
      return 0;

    return getExplicitTemplateArgs().NumTemplateArgs;
  }

  /// \brief Retrieve the member declaration name info.
  DeclarationNameInfo getMemberNameInfo() const {
    return DeclarationNameInfo(MemberDecl->getDeclName(),
                               MemberLoc, MemberDNLoc);
  }

  bool isArrow() const { return IsArrow; }
  void setArrow(bool A) { IsArrow = A; }

  /// getMemberLoc - Return the location of the "member", in X->F, it is the
  /// location of 'F'.
  SourceLocation getMemberLoc() const { return MemberLoc; }
  void setMemberLoc(SourceLocation L) { MemberLoc = L; }

  SourceLocation getLocStart() const LLVM_READONLY;
  SourceLocation getLocEnd() const LLVM_READONLY;

  SourceLocation getExprLoc() const LLVM_READONLY { return MemberLoc; }

  /// \brief Determine whether the base of this explicit is implicit.
  bool isImplicitAccess() const {
    return getBase() && getBase()->isImplicitCXXThis();
  }

  /// \brief Returns true if this member expression refers to a method that
  /// was resolved from an overloaded set having size greater than 1.
  bool hadMultipleCandidates() const {
    return HadMultipleCandidates;
  }
  /// \brief Sets the flag telling whether this expression refers to
  /// a method that was resolved from an overloaded set having size
  /// greater than 1.
  void setHadMultipleCandidates(bool V = true) {
    HadMultipleCandidates = V;
  }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == MemberExprClass;
  }

  // Iterators
  child_range children() { return child_range(&Base, &Base+1); }

  friend class ASTReader;
  friend class ASTStmtWriter;
};

/// CompoundLiteralExpr - [C99 6.5.2.5]
///
class CompoundLiteralExpr : public Expr {
  /// LParenLoc - If non-null, this is the location of the left paren in a
  /// compound literal like "(int){4}".  This can be null if this is a
  /// synthesized compound expression.
  SourceLocation LParenLoc;

  /// The type as written.  This can be an incomplete array type, in
  /// which case the actual expression type will be different.
  /// The int part of the pair stores whether this expr is file scope.
  llvm::PointerIntPair<TypeSourceInfo *, 1, bool> TInfoAndScope;
  Stmt *Init;
public:
  CompoundLiteralExpr(SourceLocation lparenloc, TypeSourceInfo *tinfo,
                      QualType T, ExprValueKind VK, Expr *init, bool fileScope)
    : Expr(CompoundLiteralExprClass, T, VK, OK_Ordinary,
           tinfo->getType()->isDependentType(),
           init->isValueDependent(),
           (init->isInstantiationDependent() ||
            tinfo->getType()->isInstantiationDependentType()),
           init->containsUnexpandedParameterPack()),
      LParenLoc(lparenloc), TInfoAndScope(tinfo, fileScope), Init(init) {}

  /// \brief Construct an empty compound literal.
  explicit CompoundLiteralExpr(EmptyShell Empty)
    : Expr(CompoundLiteralExprClass, Empty) { }

  const Expr *getInitializer() const { return cast<Expr>(Init); }
  Expr *getInitializer() { return cast<Expr>(Init); }
  void setInitializer(Expr *E) { Init = E; }

  bool isFileScope() const { return TInfoAndScope.getInt(); }
  void setFileScope(bool FS) { TInfoAndScope.setInt(FS); }

  SourceLocation getLParenLoc() const { return LParenLoc; }
  void setLParenLoc(SourceLocation L) { LParenLoc = L; }

  TypeSourceInfo *getTypeSourceInfo() const {
    return TInfoAndScope.getPointer();
  }
  void setTypeSourceInfo(TypeSourceInfo *tinfo) {
    TInfoAndScope.setPointer(tinfo);
  }

  SourceLocation getLocStart() const LLVM_READONLY {
    // FIXME: Init should never be null.
    if (!Init)
      return SourceLocation();
    if (LParenLoc.isInvalid())
      return Init->getLocStart();
    return LParenLoc;
  }
  SourceLocation getLocEnd() const LLVM_READONLY {
    // FIXME: Init should never be null.
    if (!Init)
      return SourceLocation();
    return Init->getLocEnd();
  }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == CompoundLiteralExprClass;
  }

  // Iterators
  child_range children() { return child_range(&Init, &Init+1); }
};

/// CastExpr - Base class for type casts, including both implicit
/// casts (ImplicitCastExpr) and explicit casts that have some
/// representation in the source code (ExplicitCastExpr's derived
/// classes).
class CastExpr : public Expr {
public:
  typedef clang::CastKind CastKind;

private:
  Stmt *Op;

  bool CastConsistency() const;

  const CXXBaseSpecifier * const *path_buffer() const {
    return const_cast<CastExpr*>(this)->path_buffer();
  }
  CXXBaseSpecifier **path_buffer();

  void setBasePathSize(unsigned basePathSize) {
    CastExprBits.BasePathSize = basePathSize;
    assert(CastExprBits.BasePathSize == basePathSize &&
           "basePathSize doesn't fit in bits of CastExprBits.BasePathSize!");
  }

protected:
  CastExpr(StmtClass SC, QualType ty, ExprValueKind VK,
           const CastKind kind, Expr *op, unsigned BasePathSize) :
    Expr(SC, ty, VK, OK_Ordinary,
         // Cast expressions are type-dependent if the type is
         // dependent (C++ [temp.dep.expr]p3).
         ty->isDependentType(),
         // Cast expressions are value-dependent if the type is
         // dependent or if the subexpression is value-dependent.
         ty->isDependentType() || (op && op->isValueDependent()),
         (ty->isInstantiationDependentType() ||
          (op && op->isInstantiationDependent())),
         (ty->containsUnexpandedParameterPack() ||
          (op && op->containsUnexpandedParameterPack()))),
    Op(op) {
    assert(kind != CK_Invalid && "creating cast with invalid cast kind");
    CastExprBits.Kind = kind;
    setBasePathSize(BasePathSize);
    assert(CastConsistency());
  }

  /// \brief Construct an empty cast.
  CastExpr(StmtClass SC, EmptyShell Empty, unsigned BasePathSize)
    : Expr(SC, Empty) {
    setBasePathSize(BasePathSize);
  }

public:
  CastKind getCastKind() const { return (CastKind) CastExprBits.Kind; }
  void setCastKind(CastKind K) { CastExprBits.Kind = K; }
  const char *getCastKindName() const;

  Expr *getSubExpr() { return cast<Expr>(Op); }
  const Expr *getSubExpr() const { return cast<Expr>(Op); }
  void setSubExpr(Expr *E) { Op = E; }

  /// \brief Retrieve the cast subexpression as it was written in the source
  /// code, looking through any implicit casts or other intermediate nodes
  /// introduced by semantic analysis.
  Expr *getSubExprAsWritten();
  const Expr *getSubExprAsWritten() const {
    return const_cast<CastExpr *>(this)->getSubExprAsWritten();
  }

  typedef CXXBaseSpecifier **path_iterator;
  typedef const CXXBaseSpecifier * const *path_const_iterator;
  bool path_empty() const { return CastExprBits.BasePathSize == 0; }
  unsigned path_size() const { return CastExprBits.BasePathSize; }
  path_iterator path_begin() { return path_buffer(); }
  path_iterator path_end() { return path_buffer() + path_size(); }
  path_const_iterator path_begin() const { return path_buffer(); }
  path_const_iterator path_end() const { return path_buffer() + path_size(); }

  void setCastPath(const CXXCastPath &Path);

  static bool classof(const Stmt *T) {
    return T->getStmtClass() >= firstCastExprConstant &&
           T->getStmtClass() <= lastCastExprConstant;
  }

  // Iterators
  child_range children() { return child_range(&Op, &Op+1); }
};

/// ImplicitCastExpr - Allows us to explicitly represent implicit type
/// conversions, which have no direct representation in the original
/// source code. For example: converting T[]->T*, void f()->void
/// (*f)(), float->double, short->int, etc.
///
/// In C, implicit casts always produce rvalues. However, in C++, an
/// implicit cast whose result is being bound to a reference will be
/// an lvalue or xvalue. For example:
///
/// @code
/// class Base { };
/// class Derived : public Base { };
/// Derived &&ref();
/// void f(Derived d) {
///   Base& b = d; // initializer is an ImplicitCastExpr
///                // to an lvalue of type Base
///   Base&& r = ref(); // initializer is an ImplicitCastExpr
///                     // to an xvalue of type Base
/// }
/// @endcode
class ImplicitCastExpr : public CastExpr {
private:
  ImplicitCastExpr(QualType ty, CastKind kind, Expr *op,
                   unsigned BasePathLength, ExprValueKind VK)
    : CastExpr(ImplicitCastExprClass, ty, VK, kind, op, BasePathLength) {
  }

  /// \brief Construct an empty implicit cast.
  explicit ImplicitCastExpr(EmptyShell Shell, unsigned PathSize)
    : CastExpr(ImplicitCastExprClass, Shell, PathSize) { }

public:
  enum OnStack_t { OnStack };
  ImplicitCastExpr(OnStack_t _, QualType ty, CastKind kind, Expr *op,
                   ExprValueKind VK)
    : CastExpr(ImplicitCastExprClass, ty, VK, kind, op, 0) {
  }

  static ImplicitCastExpr *Create(const ASTContext &Context, QualType T,
                                  CastKind Kind, Expr *Operand,
                                  const CXXCastPath *BasePath,
                                  ExprValueKind Cat);

  static ImplicitCastExpr *CreateEmpty(const ASTContext &Context,
                                       unsigned PathSize);

  SourceLocation getLocStart() const LLVM_READONLY {
    return getSubExpr()->getLocStart();
  }
  SourceLocation getLocEnd() const LLVM_READONLY {
    return getSubExpr()->getLocEnd();
  }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == ImplicitCastExprClass;
  }
};

inline Expr *Expr::IgnoreImpCasts() {
  Expr *e = this;
  while (ImplicitCastExpr *ice = dyn_cast<ImplicitCastExpr>(e))
    e = ice->getSubExpr();
  return e;
}

/// ExplicitCastExpr - An explicit cast written in the source
/// code.
///
/// This class is effectively an abstract class, because it provides
/// the basic representation of an explicitly-written cast without
/// specifying which kind of cast (C cast, functional cast, static
/// cast, etc.) was written; specific derived classes represent the
/// particular style of cast and its location information.
///
/// Unlike implicit casts, explicit cast nodes have two different
/// types: the type that was written into the source code, and the
/// actual type of the expression as determined by semantic
/// analysis. These types may differ slightly. For example, in C++ one
/// can cast to a reference type, which indicates that the resulting
/// expression will be an lvalue or xvalue. The reference type, however,
/// will not be used as the type of the expression.
class ExplicitCastExpr : public CastExpr {
  /// TInfo - Source type info for the (written) type
  /// this expression is casting to.
  TypeSourceInfo *TInfo;

protected:
  ExplicitCastExpr(StmtClass SC, QualType exprTy, ExprValueKind VK,
                   CastKind kind, Expr *op, unsigned PathSize,
                   TypeSourceInfo *writtenTy)
    : CastExpr(SC, exprTy, VK, kind, op, PathSize), TInfo(writtenTy) {}

  /// \brief Construct an empty explicit cast.
  ExplicitCastExpr(StmtClass SC, EmptyShell Shell, unsigned PathSize)
    : CastExpr(SC, Shell, PathSize) { }

public:
  /// getTypeInfoAsWritten - Returns the type source info for the type
  /// that this expression is casting to.
  TypeSourceInfo *getTypeInfoAsWritten() const { return TInfo; }
  void setTypeInfoAsWritten(TypeSourceInfo *writtenTy) { TInfo = writtenTy; }

  /// getTypeAsWritten - Returns the type that this expression is
  /// casting to, as written in the source code.
  QualType getTypeAsWritten() const { return TInfo->getType(); }

  static bool classof(const Stmt *T) {
     return T->getStmtClass() >= firstExplicitCastExprConstant &&
            T->getStmtClass() <= lastExplicitCastExprConstant;
  }
};

/// CStyleCastExpr - An explicit cast in C (C99 6.5.4) or a C-style
/// cast in C++ (C++ [expr.cast]), which uses the syntax
/// (Type)expr. For example: @c (int)f.
class CStyleCastExpr : public ExplicitCastExpr {
  SourceLocation LPLoc; // the location of the left paren
  SourceLocation RPLoc; // the location of the right paren

  CStyleCastExpr(QualType exprTy, ExprValueKind vk, CastKind kind, Expr *op,
                 unsigned PathSize, TypeSourceInfo *writtenTy,
                 SourceLocation l, SourceLocation r)
    : ExplicitCastExpr(CStyleCastExprClass, exprTy, vk, kind, op, PathSize,
                       writtenTy), LPLoc(l), RPLoc(r) {}

  /// \brief Construct an empty C-style explicit cast.
  explicit CStyleCastExpr(EmptyShell Shell, unsigned PathSize)
    : ExplicitCastExpr(CStyleCastExprClass, Shell, PathSize) { }

public:
  static CStyleCastExpr *Create(const ASTContext &Context, QualType T,
                                ExprValueKind VK, CastKind K,
                                Expr *Op, const CXXCastPath *BasePath,
                                TypeSourceInfo *WrittenTy, SourceLocation L,
                                SourceLocation R);

  static CStyleCastExpr *CreateEmpty(const ASTContext &Context,
                                     unsigned PathSize);

  SourceLocation getLParenLoc() const { return LPLoc; }
  void setLParenLoc(SourceLocation L) { LPLoc = L; }

  SourceLocation getRParenLoc() const { return RPLoc; }
  void setRParenLoc(SourceLocation L) { RPLoc = L; }

  SourceLocation getLocStart() const LLVM_READONLY { return LPLoc; }
  SourceLocation getLocEnd() const LLVM_READONLY {
    return getSubExpr()->getLocEnd();
  }

  static bool classof(const Stmt *T) {
    return T->getStmtClass() == CStyleCastExprClass;
  }
};

/// \brief A builtin binary operation expression such as "x + y" or "x <= y".
///
/// This expression node kind describes a builtin binary operation,
/// such as "x + y" for integer values "x" and "y". The operands will
/// already have been converted to appropriate types (e.g., by
/// performing promotions or conversions).
///
/// In C++, where operators may be overloaded, a different kind of
/// expression node (CXXOperatorCallExpr) is used to express the
/// invocation of an overloaded operator with operator syntax. Within
/// a C++ template, whether BinaryOperator or CXXOperatorCallExpr is
/// used to store an expression "x + y" depends on the subexpressions
/// for x and y. If neither x or y is type-dependent, and the "+"
/// operator resolves to a built-in operation, BinaryOperator will be
/// used to express the computation (x and y may still be
/// value-dependent). If either x or y is type-dependent, or if the
/// "+" resolves to an overloaded operator, CXXOperatorCallExpr will
/// be used to express the computation.
class BinaryOperator : public Expr {
public:
  typedef BinaryOperatorKind Opcode;

private:
  unsigned Opc : 6;

  // Records the FP_CONTRACT pragma status at the point that this binary
  // operator was parsed. This bit is only meaningful for operations on
  // floating point types. For all other types it should default to
  // false.
  unsigned FPContractable : 1;
  SourceLocation OpLoc;

  enum { LHS, RHS, END_EXPR };
  Stmt* SubExprs[END_EXPR];
public:

  BinaryOperator(Expr *lhs, Expr *rhs, Opcode opc, QualType ResTy,
                 ExprValueKind VK, ExprObjectKind OK,
                 SourceLocation opLoc, bool fpContractable)
    : Expr(BinaryOperatorClass, ResTy, VK, OK,
           lhs->isTypeDependent() || rhs->isTypeDependent(),
           lhs->isValueDependent() || rhs->isValueDependent(),
           (lhs->isInstantiationDependent() ||
            rhs->isInstantiationDependent()),
           (lhs->containsUnexpandedParameterPack() ||
            rhs->containsUnexpandedParameterPack())),
      Opc(opc), FPContractable(fpContractable), OpLoc(opLoc) {
    SubExprs[LHS] = lhs;
    SubExprs[RHS] = rhs;
    assert(!isCompoundAssignmentOp() &&
           "Use CompoundAssignOperator for compound assignments");
  }

  /// \brief Construct an empty binary operator.
  explicit BinaryOperator(EmptyShell Empty)
    : Expr(BinaryOperatorClass, Empty), Opc(BO_Comma) { }

  SourceLocation getExprLoc() const LLVM_READONLY { return OpLoc; }
  SourceLocation getOperatorLoc() const { return OpLoc; }
  void setOperatorLoc(SourceLocation L) { OpLoc = L; }

  Opcode getOpcode() const { return static_cast<Opcode>(Opc); }
  void setOpcode(Opcode O) { Opc = O; }

  Expr *getLHS() const { return cast<Expr>(SubExprs[LHS]); }
  void setLHS(Expr *E) { SubExprs[LHS] = E; }
  Expr *getRHS() const { return cast<Expr>(SubExprs[RHS]); }
  void setRHS(Expr *E) { SubExprs[RHS] = E; }

  SourceLocation getLocStart() const LLVM_READONLY {
    return getLHS()->getLocStart();
  }
  SourceLocation getLocEnd() const LLVM_READONLY {
    return getRHS()->getLocEnd();
  }

  /// getOpcodeStr - Turn an Opcode enum value into the punctuation char it
  /// corresponds to, e.g. "<<=".
  static StringRef getOpcodeStr(Opcode Op);

  StringRef getOpcodeStr() const { return getOpcodeStr(getOpcode()); }

  /// \brief Retrieve the binary opcode that corresponds to the given
  /// overloaded operator.
  static Opcode getOverloadedOpcode(OverloadedOperatorKind OO);

  /// \brief Retrieve the overloaded operator kind that corresponds to
  /// the given binary opcode.
  static OverloadedOperatorKind getOverloadedOperator(Opcode Opc);

  /// predicates to categorize the respective opcodes.
  bool isPtrMemOp() const { return Opc == BO_PtrMemD || Opc == BO_PtrMemI; }
  bool isMultiplicativeOp() const { return Opc >= BO_Mul && Opc <= BO_Rem; }
  static bool isAdditiveOp(Opcode Opc) { return Opc == BO_Add || Opc==BO_Sub; }
  bool isAdditiveOp() const { return isAdditiveOp(getOpcode()); }
  static bool isShiftOp(Opcode Opc) { return Opc == BO_Shl || Opc == BO_Shr; }
  bool isShiftOp() const { return isShiftOp(getOpcode()); }

  static bool isBitwiseOp(Opcode Opc) { return Opc >= BO_And && Opc <= BO_Or; }
  bool isBitwiseOp() const { return isBitwiseOp(getOpcode()); }

  static bool isRelationalOp(Opcode Opc) { return Opc >= BO_LT && Opc<=BO_GE; }
  bool isRelationalOp() const { return isRelationalOp(getOpcode()); }

  static bool isEqualityOp(Opcode Opc) { return Opc == BO_EQ || Opc == BO_NE; }
  bool isEqualityOp() const { return isEqualityOp(getOpcode()); }

  static bool isComparisonOp(Opcode Opc) { return Opc >= BO_LT && Opc<=BO_NE; }
  bool isComparisonOp() const { return isComparisonOp(getOpcode()); }

  static Opcode negateComparisonOp(Opcode Opc) {
    switch (Opc) {
    default:
      llvm_unreachable("Not a comparsion operator.");
    case BO_LT: return BO_GE;
    case BO_GT: return BO_LE;
    case BO_LE: return BO_GT;
    case BO_GE: return BO_LT;
    case BO_EQ: return BO_NE;
    case BO_NE: return BO_EQ;
    }
  }

  static Opcode reverseComparisonOp(Opcode Opc) {
    switch (Opc) {
    default:
      llvm_unreachable("Not a comparsion operator.");
    case BO_LT: return BO_GT;
    case BO_GT: return BO_LT;
    case BO_LE: return BO_GE;
    case BO_GE: return BO_LE;
    case BO_EQ:
    case BO_NE:
      return Opc;
    }
  }

  static bool isLogicalOp(Opcode Opc) { return Opc == BO_LAnd || Opc==BO_LOr; }
  bool isLogicalOp() const { return isLogicalOp(getOpcode()); }

  static bool isAssignmentOp(Opcode Opc) {
    return Opc >= BO_Assign && Opc <= BO_OrAssign;
  }
  bool isAssignmentOp() const { return isAssignmentOp(getOpcode()); }

  static bool isCompoundAssignmentOp(Opcode Opc) {
    return Opc > BO_Assign && Opc <= BO_OrAssign;
  }
  bool isCompoundAssignmentOp() const {
    return isCompoundAssignmentOp(getOpcode());
  }
  static Opcode getOpForCompoundAssignment(Opcode Opc) {
    assert(isCompoundAssignmentOp(Opc));
    if (Opc >= BO_AndAssign)
      return Opcode(unsigned(Opc) - BO_AndAssign + BO_And);
    else
      return Opcode(unsigned(Opc) - BO_MulAssign + BO_Mul);
  }

  static bool isShiftAssignOp(Opcode Opc) {
    return Opc == BO_ShlAssign || Opc == BO_ShrAssign;
  }
  bool isShiftAssignOp() const {
    return isShiftAssignOp(getOpcode());
  }

  static bool classof(const Stmt *S) {
    return S->getStmtClass() >= firstBinaryOperatorConstant &&
           S->getStmtClass() <= lastBinaryOperatorConstant;
  }

  // Iterators
  child_range children() {
    return child_range(&SubExprs[0], &SubExprs[0]+END_EXPR);
  }

  // Set the FP contractability status of this operator. Only meaningful for
  // operations on floating point types.
  void setFPContractable(bool FPC) { FPContractable = FPC; }

  // Get the FP contractability status of this operator. Only meaningful for
  // operations on floating point types.
  bool isFPContractable() const { return FPContractable; }

protected:
  BinaryOperator(Expr *lhs, Expr *rhs, Opcode opc, QualType ResTy,
                 ExprValueKind VK, ExprObjectKind OK,
                 SourceLocation opLoc, bool fpContractable, bool dead2)
    : Expr(CompoundAssignOperatorClass, ResTy, VK, OK,
           lhs->isTypeDependent() || rhs->isTypeDependent(),
           lhs->isValueDependent() || rhs->isValueDependent(),
           (lhs->isInstantiationDependent() ||
            rhs->isInstantiationDependent()),
           (lhs->containsUnexpandedParameterPack() ||
            rhs->containsUnexpandedParameterPack())),
      Opc(opc), FPContractable(fpContractable), OpLoc(opLoc) {
    SubExprs[LHS] = lhs;
    SubExprs[RHS] = rhs;
  }

  BinaryOperator(StmtClass SC, EmptyShell Empty)
    : Expr(SC, Empty), Opc(BO_MulAssign) { }
};

/// CompoundAssignOperator - For compound assignments (e.g. +=), we keep
/// track of the type the operation is performed in.  Due to the semantics of
/// these operators, the operands are promoted, the arithmetic performed, an
/// implicit conversion back to the result type done, then the assignment takes
/// place.  This captures the intermediate type which the computation is done
/// in.
class CompoundAssignOperator : public BinaryOperator {
  QualType ComputationLHSType;
  QualType ComputationResultType;
public:
  CompoundAssignOperator(Expr *lhs, Expr *rhs, Opcode opc, QualType ResType,
                         ExprValueKind VK, ExprObjectKind OK,
                         QualType CompLHSType, QualType CompResultType,
                         SourceLocation OpLoc, bool fpContractable)
    : BinaryOperator(lhs, rhs, opc, ResType, VK, OK, OpLoc, fpContractable,
                     true),
      ComputationLHSType(CompLHSType),
      ComputationResultType(CompResultType) {
    assert(isCompoundAssignmentOp() &&
           "Only should be used for compound assignments");
  }

  /// \brief Build an empty compound assignment operator expression.