text: //===--- Expr.h - Classes for representing expressions ----------*- C++ -*-===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  //  This file defines 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/ComputeDependence.h"
  #include "clang/AST/Decl.h"
  #include "clang/AST/DeclAccessPair.h"
  #include "clang/AST/DependenceFlags.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/LangOptions.h"
  #include "clang/Basic/SyncScope.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/ADT/iterator.h"
  #include "llvm/ADT/iterator_range.h"
  #include "llvm/Support/AtomicOrdering.h"
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/TrailingObjects.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 StringLiteral;
    class TargetInfo;
    class ValueDecl;
  
  /// A simple array of base specifiers.
  typedef SmallVector<CXXBaseSpecifier*, 4> CXXCastPath;
  
  /// 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;
    }
  };
  
  /// 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 ValueStmt {
    QualType TR;
  
  public:
    Expr() = delete;
    Expr(const Expr&) = delete;
    Expr(Expr &&) = delete;
    Expr &operator=(const Expr&) = delete;
    Expr &operator=(Expr&&) = delete;
  
  protected:
    Expr(StmtClass SC, QualType T, ExprValueKind VK, ExprObjectKind OK)
        : ValueStmt(SC) {
      ExprBits.Dependent = 0;
      ExprBits.ValueKind = VK;
      ExprBits.ObjectKind = OK;
      assert(ExprBits.ObjectKind == OK && "truncated kind");
      setType(T);
    }
  
    /// Construct an empty expression.
    explicit Expr(StmtClass SC, EmptyShell) : ValueStmt(SC) { }
  
    /// Each concrete expr subclass is expected to compute its dependence and call
    /// this in the constructor.
    void setDependence(ExprDependence Deps) {
      ExprBits.Dependent = static_cast<unsigned>(Deps);
    }
    friend class ASTImporter; // Sets dependence dircetly.
    friend class ASTStmtReader; // Sets dependence dircetly.
  
  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 (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;
    }
  
    ExprDependence getDependence() const {
      return static_cast<ExprDependence>(ExprBits.Dependent);
    }
  
    /// Determines whether the value of this expression depends on
    ///   - a template parameter (C++ [temp.dep.constexpr])
    ///   - or an error, whose resolution is unknown
    ///
    /// 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 static_cast<bool>(getDependence() & ExprDependence::Value);
    }
  
    /// Determines whether the type of this expression depends on
    ///   - a template paramter (C++ [temp.dep.expr], which means that its type
    ///     could change from one template instantiation to the next)
    ///   - or an error
    ///
    /// 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 static_cast<bool>(getDependence() & ExprDependence::Type);
    }
  
    /// 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)
    ///    - or an error
    ///
    /// 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
    ///
    /// \code
    /// void func(int) {
    ///   func(); // the expression is instantiation-dependent, because it depends
    ///           // on an error.
    /// }
    /// \endcode
    bool isInstantiationDependent() const {
      return static_cast<bool>(getDependence() & ExprDependence::Instantiation);
    }
  
    /// 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 static_cast<bool>(getDependence() & ExprDependence::UnexpandedPack);
    }
  
    /// Whether this expression contains subexpressions which had errors, e.g. a
    /// TypoExpr.
    bool containsErrors() const {
      return static_cast<bool>(getDependence() & ExprDependence::Error);
    }
  
    /// getExprLoc - Return the preferred location for the arrow when diagnosing
    /// a problem with a generic expression.
    SourceLocation getExprLoc() const LLVM_READONLY;
  
    /// Determine whether an lvalue-to-rvalue conversion should implicitly be
    /// applied to this expression if it appears as a discarded-value expression
    /// in C++11 onwards. This applies to certain forms of volatile glvalues.
    bool isReadIfDiscardedInCPlusPlus11() const;
  
    /// 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.
    bool isLValue() const { return getValueKind() == VK_LValue; }
    bool isPRValue() const { return getValueKind() == VK_PRValue; }
    bool isXValue() const { return getValueKind() == VK_XValue; }
    bool isGLValue() const { return getValueKind() != VK_PRValue; }
  
    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_ConstQualifiedField,
      MLV_ConstAddrSpace,
      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;
  
    /// The return type of classify(). Represents the C++11 expression
    ///        taxonomy.
    class Classification {
    public:
      /// 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
      };
      /// 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_ConstQualifiedField,
        CM_ConstAddrSpace,
        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; }
  
      /// Create a simple, modifiably lvalue
      static Classification makeSimpleLValue() {
        return Classification(CL_LValue, CM_Modifiable);
      }
  
    };
    /// 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);
    }
  
    /// 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);
    }
  
    /// Returns the set of floating point options that apply to this expression.
    /// Only meaningful for operations on floating point values.
    FPOptions getFPFeaturesInEffect(const LangOptions &LO) const;
  
    /// 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_PRValue;
    }
  
    /// 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:
  
    /// 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; }
  
    /// 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();
    }
  
    Decl *getReferencedDeclOfCallee();
    const Decl *getReferencedDeclOfCallee() const {
      return const_cast<Expr*>(this)->getReferencedDeclOfCallee();
    }
  
    /// If this expression is an l-value for an Objective C
    /// property, find the underlying property reference expression.
    const ObjCPropertyRefExpr *getObjCProperty() const;
  
    /// Check if this expression is the ObjC 'self' implicit parameter.
    bool isObjCSelfExpr() const;
  
    /// Returns whether this expression refers to a vector element.
    bool refersToVectorElement() const;
  
    /// Returns whether this expression refers to a matrix element.
    bool refersToMatrixElement() const {
      return getObjectKind() == OK_MatrixComponent;
    }
  
    /// Returns whether this expression refers to a global register
    /// variable.
    bool refersToGlobalRegisterVar() const;
  
    /// Returns whether this expression has a placeholder type.
    bool hasPlaceholderType() const {
      return getType()->isPlaceholderType();
    }
  
    /// 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.
    ///
    /// \param Semantic If true, only return true for expressions that are known
    /// to be semantically boolean, which might not be true even for expressions
    /// that are known to evaluate to 0/1. For instance, reading an unsigned
    /// bit-field with width '1' will evaluate to 0/1, but doesn't necessarily
    /// semantically correspond to a bool.
    bool isKnownToHaveBooleanValue(bool Semantic = true) const;
  
    /// isIntegerConstantExpr - Return the value if this expression is a valid
    /// integer constant expression.  If not a valid i-c-e, return None 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.
    Optional<llvm::APSInt> getIntegerConstantExpr(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 {
      /// Whether the evaluated expression has side effects.
      /// For example, (f() && 0) can be folded, but it still has side effects.
      bool HasSideEffects;
  
      /// Whether the evaluation hit undefined behavior.
      /// For example, 1.0 / 0.0 can be folded to Inf, but has undefined behavior.
      /// Likewise, INT_MAX + 1 can be folded to INT_MIN, but has UB.
      bool HasUndefinedBehavior;
  
      /// 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), HasUndefinedBehavior(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,
                          bool InConstantContext = false) const;
  
    /// EvaluateAsBooleanCondition - Return true if this is a constant
    /// which 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,
                                    bool InConstantContext = false) const;
  
    enum SideEffectsKind {
      SE_NoSideEffects,          ///< Strictly evaluate the expression.
      SE_AllowUndefinedBehavior, ///< Allow UB that we can give a value, but not
                                 ///< arbitrary unmodeled side effects.
      SE_AllowSideEffects        ///< Allow any unmodeled side effect.
    };
  
    /// 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(EvalResult &Result, const ASTContext &Ctx,
                       SideEffectsKind AllowSideEffects = SE_NoSideEffects,
                       bool InConstantContext = false) const;
  
    /// EvaluateAsFloat - Return true if this is a constant which we can fold and
    /// convert to a floating point value, using any crazy technique that we
    /// want to.
    bool EvaluateAsFloat(llvm::APFloat &Result, const ASTContext &Ctx,
                         SideEffectsKind AllowSideEffects = SE_NoSideEffects,
                         bool InConstantContext = false) const;
  
    /// EvaluateAsFloat - Return true if this is a constant which we can fold and
    /// convert to a fixed point value.
    bool EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx,
                              SideEffectsKind AllowSideEffects = SE_NoSideEffects,
                              bool InConstantContext = false) 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,
                       SideEffectsKind AllowSideEffects = SE_NoSideEffects) 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. If
    /// IncludePossibleEffects is false, this call treats certain expressions with
    /// potential side effects (such as function call-like expressions,
    /// instantiation-dependent expressions, or invocations from a macro) as not
    /// having side effects.
    bool HasSideEffects(const ASTContext &Ctx,
                        bool IncludePossibleEffects = true) const;
  
    /// Determine whether this expression involves a call to any function
    /// that is not trivial.
    bool hasNonTrivialCall(const ASTContext &Ctx) const;
  
    /// 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;
  
    llvm::APSInt EvaluateKnownConstIntCheckOverflow(
        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,
                          bool InConstantContext = false) 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,
                               bool IsConstantInitializer) 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 Expr *This = nullptr) const;
  
    enum class ConstantExprKind {
      /// An integer constant expression (an array bound, enumerator, case value,
      /// bit-field width, or similar) or similar.
      Normal,
      /// A non-class template argument. Such a value is only used for mangling,
      /// not for code generation, so can refer to dllimported functions.
      NonClassTemplateArgument,
      /// A class template argument. Such a value is used for code generation.
      ClassTemplateArgument,
      /// An immediate invocation. The destruction of the end result of this
      /// evaluation is not part of the evaluation, but all other temporaries
      /// are destroyed.
      ImmediateInvocation,
    };
  
    /// Evaluate an expression that is required to be a constant expression. Does
    /// not check the syntactic constraints for C and C++98 constant expressions.
    bool EvaluateAsConstantExpr(
        EvalResult &Result, const ASTContext &Ctx,
        ConstantExprKind Kind = ConstantExprKind::Normal) const;
  
    /// If the current Expr is a pointer, this will try to statically
    /// determine the number of bytes available where the pointer is pointing.
    /// Returns true if all of the above holds and we were able to figure out the
    /// size, false otherwise.
    ///
    /// \param Type - How to evaluate the size of the Expr, as defined by the
    /// "type" parameter of __builtin_object_size
    bool tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
                               unsigned Type) const;
  
    /// Enumeration used to describe the kind of Null pointer constant
    /// returned from \c isNullPointerConstant().
    enum NullPointerConstantKind {
      /// Expression is not a Null pointer constant.
      NPCK_NotNull = 0,
  
      /// 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,
  
      /// Expression is a Null pointer constant built from a literal zero.
      NPCK_ZeroLiteral,
  
      /// Expression is a C++11 nullptr.
      NPCK_CXX11_nullptr,
  
      /// Expression is a GNU-style __null constant.
      NPCK_GNUNull
    };
  
    /// Enumeration used to describe how \c isNullPointerConstant()
    /// should cope with value-dependent expressions.
    enum NullPointerConstantValueDependence {
      /// Specifies that the expression should never be value-dependent.
      NPC_NeverValueDependent = 0,
  
      /// Specifies that a value-dependent expression of integral or
      /// dependent type should be considered a null pointer constant.
      NPC_ValueDependentIsNull,
  
      /// 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;
  
    /// Returns true if this expression is a bound member function.
    bool isBoundMemberFunction(ASTContext &Ctx) const;
  
    /// 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);
  
    /// Skip past any invisble AST nodes which might surround this
    /// statement, such as ExprWithCleanups or ImplicitCastExpr nodes,
    /// but also injected CXXMemberExpr and CXXConstructExpr which represent
    /// implicit conversions.
    Expr *IgnoreUnlessSpelledInSource();
    const Expr *IgnoreUnlessSpelledInSource() const {
      return const_cast<Expr *>(this)->IgnoreUnlessSpelledInSource();
    }
  
    /// Skip past any implicit casts which might surround this expression until
    /// reaching a fixed point. Skips:
    /// * ImplicitCastExpr
    /// * FullExpr
    Expr *IgnoreImpCasts() LLVM_READONLY;
    const Expr *IgnoreImpCasts() const {
      return const_cast<Expr *>(this)->IgnoreImpCasts();
    }
  
    /// Skip past any casts which might surround this expression until reaching
    /// a fixed point. Skips:
    /// * CastExpr
    /// * FullExpr
    /// * MaterializeTemporaryExpr
    /// * SubstNonTypeTemplateParmExpr
    Expr *IgnoreCasts() LLVM_READONLY;
    const Expr *IgnoreCasts() const {
      return const_cast<Expr *>(this)->IgnoreCasts();
    }
  
    /// Skip past any implicit AST nodes which might surround this expression
    /// until reaching a fixed point. Skips:
    /// * What IgnoreImpCasts() skips
    /// * MaterializeTemporaryExpr
    /// * CXXBindTemporaryExpr
    Expr *IgnoreImplicit() LLVM_READONLY;
    const Expr *IgnoreImplicit() const {
      return const_cast<Expr *>(this)->IgnoreImplicit();
    }
  
    /// Skip past any implicit AST nodes which might surround this expression
    /// until reaching a fixed point. Same as IgnoreImplicit, except that it
    /// also skips over implicit calls to constructors and conversion functions.
    ///
    /// FIXME: Should IgnoreImplicit do this?
    Expr *IgnoreImplicitAsWritten() LLVM_READONLY;
    const Expr *IgnoreImplicitAsWritten() const {
      return const_cast<Expr *>(this)->IgnoreImplicitAsWritten();
    }
  
    /// Skip past any parentheses which might surround this expression until
    /// reaching a fixed point. Skips:
    /// * ParenExpr
    /// * UnaryOperator if `UO_Extension`
    /// * GenericSelectionExpr if `!isResultDependent()`
    /// * ChooseExpr if `!isConditionDependent()`
    /// * ConstantExpr
    Expr *IgnoreParens() LLVM_READONLY;
    const Expr *IgnoreParens() const {
      return const_cast<Expr *>(this)->IgnoreParens();
    }
  
    /// Skip past any parentheses and implicit casts which might surround this
    /// expression until reaching a fixed point.
    /// FIXME: IgnoreParenImpCasts really ought to be equivalent to
    /// IgnoreParens() + IgnoreImpCasts() until reaching a fixed point. However
    /// this is currently not the case. Instead IgnoreParenImpCasts() skips:
    /// * What IgnoreParens() skips
    /// * What IgnoreImpCasts() skips
    /// * MaterializeTemporaryExpr
    /// * SubstNonTypeTemplateParmExpr
    Expr *IgnoreParenImpCasts() LLVM_READONLY;
    const Expr *IgnoreParenImpCasts() const {
      return const_cast<Expr *>(this)->IgnoreParenImpCasts();
    }
  
    /// Skip past any parentheses and casts which might surround this expression
    /// until reaching a fixed point. Skips:
    /// * What IgnoreParens() skips
    /// * What IgnoreCasts() skips
    Expr *IgnoreParenCasts() LLVM_READONLY;
    const Expr *IgnoreParenCasts() const {
      return const_cast<Expr *>(this)->IgnoreParenCasts();
    }
  
    /// Skip conversion operators. If this Expr is a call to a conversion
    /// operator, return the argument.
    Expr *IgnoreConversionOperatorSingleStep() LLVM_READONLY;
    const Expr *IgnoreConversionOperatorSingleStep() const {
      return const_cast<Expr *>(this)->IgnoreConversionOperatorSingleStep();
    }
  
    /// Skip past any parentheses and lvalue casts which might surround this
    /// expression until reaching a fixed point. Skips:
    /// * What IgnoreParens() skips
    /// * What IgnoreCasts() skips, except that only lvalue-to-rvalue
    ///   casts are skipped
    /// FIXME: This is intended purely as a temporary workaround for code
    /// that hasn't yet been rewritten to do the right thing about those
    /// casts, and may disappear along with the last internal use.
    Expr *IgnoreParenLValueCasts() LLVM_READONLY;
    const Expr *IgnoreParenLValueCasts() const {
      return const_cast<Expr *>(this)->IgnoreParenLValueCasts();
    }
  
    /// Skip past any parenthese and casts which do not change the value
    /// (including ptr->int casts of the same size) until reaching a fixed point.
    /// Skips:
    /// * What IgnoreParens() skips
    /// * CastExpr which do not change the value
    /// * SubstNonTypeTemplateParmExpr
    Expr *IgnoreParenNoopCasts(const ASTContext &Ctx) LLVM_READONLY;
    const Expr *IgnoreParenNoopCasts(const ASTContext &Ctx) const {
      return const_cast<Expr *>(this)->IgnoreParenNoopCasts(Ctx);
    }
  
    /// Skip past any parentheses and derived-to-base casts until reaching a
    /// fixed point. Skips:
    /// * What IgnoreParens() skips
    /// * CastExpr which represent a derived-to-base cast (CK_DerivedToBase,
    ///   CK_UncheckedDerivedToBase and CK_NoOp)
    Expr *IgnoreParenBaseCasts() LLVM_READONLY;
    const Expr *IgnoreParenBaseCasts() const {
      return const_cast<Expr *>(this)->IgnoreParenBaseCasts();
    }
  
    /// 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;
  
    /// Determine whether the result of this expression is a
    /// temporary object of the given class type.
    bool isTemporaryObject(ASTContext &Ctx, const CXXRecordDecl *TempTy) const;
  
    /// Whether this expression is an implicit reference to 'this' in C++.
    bool isImplicitCXXThis() const;
  
    static bool hasAnyTypeDependentArguments(ArrayRef<Expr *> Exprs);
  
    /// 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;
  
    /// Get the inner expression that determines the best dynamic class.
    /// If this is a prvalue, we guarantee that it is of the most-derived type
    /// for the object itself.
    const Expr *getBestDynamicClassTypeExpr() 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;
    const Expr *skipRValueSubobjectAdjustments() const {
      SmallVector<const Expr *, 8> CommaLHSs;
      SmallVector<SubobjectAdjustment, 8> Adjustments;
      return skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
    }
  
    /// Checks that the two Expr's will refer to the same value as a comparison
    /// operand.  The caller must ensure that the values referenced by the Expr's
    /// are not modified between E1 and E2 or the result my be invalid.
    static bool isSameComparisonOperand(const Expr* E1, const Expr* E2);
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() >= firstExprConstant &&
             T->getStmtClass() <= lastExprConstant;
    }
  };
  // PointerLikeTypeTraits is specialized so it can be used with a forward-decl of
  // Expr. Verify that we got it right.
  static_assert(llvm::PointerLikeTypeTraits<Expr *>::NumLowBitsAvailable <=
                    llvm::detail::ConstantLog2<alignof(Expr)>::value,
                "PointerLikeTypeTraits<Expr*> assumes too much alignment.");
  
  using ConstantExprKind = Expr::ConstantExprKind;
  
  //===----------------------------------------------------------------------===//
  // Wrapper Expressions.
  //===----------------------------------------------------------------------===//
  
  /// FullExpr - Represents a "full-expression" node.
  class FullExpr : public Expr {
  protected:
   Stmt *SubExpr;
  
   FullExpr(StmtClass SC, Expr *subexpr)
       : Expr(SC, subexpr->getType(), subexpr->getValueKind(),
              subexpr->getObjectKind()),
         SubExpr(subexpr) {
     setDependence(computeDependence(this));
   }
    FullExpr(StmtClass SC, EmptyShell Empty)
      : Expr(SC, Empty) {}
  public:
    const Expr *getSubExpr() const { return cast<Expr>(SubExpr); }
    Expr *getSubExpr() { return cast<Expr>(SubExpr); }
  
    /// As with any mutator of the AST, be very careful when modifying an
    /// existing AST to preserve its invariants.
    void setSubExpr(Expr *E) { SubExpr = E; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() >= firstFullExprConstant &&
             T->getStmtClass() <= lastFullExprConstant;
    }
  };
  
  /// ConstantExpr - An expression that occurs in a constant context and
  /// optionally the result of evaluating the expression.
  class ConstantExpr final
      : public FullExpr,
        private llvm::TrailingObjects<ConstantExpr, APValue, uint64_t> {
    static_assert(std::is_same<uint64_t, llvm::APInt::WordType>::value,
                  "ConstantExpr assumes that llvm::APInt::WordType is uint64_t "
                  "for tail-allocated storage");
    friend TrailingObjects;
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
  
  public:
    /// Describes the kind of result that can be tail-allocated.
    enum ResultStorageKind { RSK_None, RSK_Int64, RSK_APValue };
  
  private:
    size_t numTrailingObjects(OverloadToken<APValue>) const {
      return ConstantExprBits.ResultKind == ConstantExpr::RSK_APValue;
    }
    size_t numTrailingObjects(OverloadToken<uint64_t>) const {
      return ConstantExprBits.ResultKind == ConstantExpr::RSK_Int64;
    }
  
    uint64_t &Int64Result() {
      assert(ConstantExprBits.ResultKind == ConstantExpr::RSK_Int64 &&
             "invalid accessor");
      return *getTrailingObjects<uint64_t>();
    }
    const uint64_t &Int64Result() const {
      return const_cast<ConstantExpr *>(this)->Int64Result();
    }
    APValue &APValueResult() {
      assert(ConstantExprBits.ResultKind == ConstantExpr::RSK_APValue &&
             "invalid accessor");
      return *getTrailingObjects<APValue>();
    }
    APValue &APValueResult() const {
      return const_cast<ConstantExpr *>(this)->APValueResult();
    }
  
    ConstantExpr(Expr *SubExpr, ResultStorageKind StorageKind,
                 bool IsImmediateInvocation);
    ConstantExpr(EmptyShell Empty, ResultStorageKind StorageKind);
  
  public:
    static ConstantExpr *Create(const ASTContext &Context, Expr *E,
                                const APValue &Result);
    static ConstantExpr *Create(const ASTContext &Context, Expr *E,
                                ResultStorageKind Storage = RSK_None,
                                bool IsImmediateInvocation = false);
    static ConstantExpr *CreateEmpty(const ASTContext &Context,
                                     ResultStorageKind StorageKind);
  
    static ResultStorageKind getStorageKind(const APValue &Value);
    static ResultStorageKind getStorageKind(const Type *T,
                                            const ASTContext &Context);
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return SubExpr->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return SubExpr->getEndLoc();
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ConstantExprClass;
    }
  
    void SetResult(APValue Value, const ASTContext &Context) {
      MoveIntoResult(Value, Context);
    }
    void MoveIntoResult(APValue &Value, const ASTContext &Context);
  
    APValue::ValueKind getResultAPValueKind() const {
      return static_cast<APValue::ValueKind>(ConstantExprBits.APValueKind);
    }
    ResultStorageKind getResultStorageKind() const {
      return static_cast<ResultStorageKind>(ConstantExprBits.ResultKind);
    }
    bool isImmediateInvocation() const {
      return ConstantExprBits.IsImmediateInvocation;
    }
    bool hasAPValueResult() const {
      return ConstantExprBits.APValueKind != APValue::None;
    }
    APValue getAPValueResult() const;
    APValue &getResultAsAPValue() const { return APValueResult(); }
    llvm::APSInt getResultAsAPSInt() const;
    // Iterators
    child_range children() { return child_range(&SubExpr, &SubExpr+1); }
    const_child_range children() const {
      return const_child_range(&SubExpr, &SubExpr + 1);
    }
  };
  
  //===----------------------------------------------------------------------===//
  // 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;
  
  public:
    OpaqueValueExpr(SourceLocation Loc, QualType T, ExprValueKind VK,
                    ExprObjectKind OK = OK_Ordinary, Expr *SourceExpr = nullptr)
        : Expr(OpaqueValueExprClass, T, VK, OK), SourceExpr(SourceExpr) {
      setIsUnique(false);
      OpaqueValueExprBits.Loc = Loc;
      setDependence(computeDependence(this));
    }
  
    /// 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) {}
  
    /// Retrieve the location of this expression.
    SourceLocation getLocation() const { return OpaqueValueExprBits.Loc; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return SourceExpr ? SourceExpr->getBeginLoc() : getLocation();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return SourceExpr ? SourceExpr->getEndLoc() : getLocation();
    }
    SourceLocation getExprLoc() const LLVM_READONLY {
      return SourceExpr ? SourceExpr->getExprLoc() : getLocation();
    }
  
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
  
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  
    /// 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; }
  
    void setIsUnique(bool V) {
      assert((!V || SourceExpr) &&
             "unique OVEs are expected to have source expressions");
      OpaqueValueExprBits.IsUnique = V;
    }
  
    bool isUnique() const { return OpaqueValueExprBits.IsUnique; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == OpaqueValueExprClass;
    }
  };
  
  /// 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.RefersToEnclosingVariableOrCapture
  ///       Specifies when this declaration reference expression (validly)
  ///       refers to an enclosed local or a captured variable.
  class DeclRefExpr final
      : public Expr,
        private llvm::TrailingObjects<DeclRefExpr, NestedNameSpecifierLoc,
                                      NamedDecl *, ASTTemplateKWAndArgsInfo,
                                      TemplateArgumentLoc> {
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
    friend TrailingObjects;
  
    /// The declaration that we are referencing.
    ValueDecl *D;
  
    /// Provides source/type location info for the declaration name
    /// embedded in D.
    DeclarationNameLoc DNLoc;
  
    size_t numTrailingObjects(OverloadToken<NestedNameSpecifierLoc>) const {
      return hasQualifier();
    }
  
    size_t numTrailingObjects(OverloadToken<NamedDecl *>) const {
      return hasFoundDecl();
    }
  
    size_t numTrailingObjects(OverloadToken<ASTTemplateKWAndArgsInfo>) const {
      return hasTemplateKWAndArgsInfo();
    }
  
    /// Test whether there is a distinct FoundDecl attached to the end of
    /// this DRE.
    bool hasFoundDecl() const { return DeclRefExprBits.HasFoundDecl; }
  
    DeclRefExpr(const ASTContext &Ctx, NestedNameSpecifierLoc QualifierLoc,
                SourceLocation TemplateKWLoc, ValueDecl *D,
                bool RefersToEnlosingVariableOrCapture,
                const DeclarationNameInfo &NameInfo, NamedDecl *FoundD,
                const TemplateArgumentListInfo *TemplateArgs, QualType T,
                ExprValueKind VK, NonOdrUseReason NOUR);
  
    /// Construct an empty declaration reference expression.
    explicit DeclRefExpr(EmptyShell Empty) : Expr(DeclRefExprClass, Empty) {}
  
  public:
    DeclRefExpr(const ASTContext &Ctx, ValueDecl *D,
                bool RefersToEnclosingVariableOrCapture, QualType T,
                ExprValueKind VK, SourceLocation L,
                const DeclarationNameLoc &LocInfo = DeclarationNameLoc(),
                NonOdrUseReason NOUR = NOUR_None);
  
    static DeclRefExpr *
    Create(const ASTContext &Context, NestedNameSpecifierLoc QualifierLoc,
           SourceLocation TemplateKWLoc, ValueDecl *D,
           bool RefersToEnclosingVariableOrCapture, SourceLocation NameLoc,
           QualType T, ExprValueKind VK, NamedDecl *FoundD = nullptr,
           const TemplateArgumentListInfo *TemplateArgs = nullptr,
           NonOdrUseReason NOUR = NOUR_None);
  
    static DeclRefExpr *
    Create(const ASTContext &Context, NestedNameSpecifierLoc QualifierLoc,
           SourceLocation TemplateKWLoc, ValueDecl *D,
           bool RefersToEnclosingVariableOrCapture,
           const DeclarationNameInfo &NameInfo, QualType T, ExprValueKind VK,
           NamedDecl *FoundD = nullptr,
           const TemplateArgumentListInfo *TemplateArgs = nullptr,
           NonOdrUseReason NOUR = NOUR_None);
  
    /// 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);
  
    DeclarationNameInfo getNameInfo() const {
      return DeclarationNameInfo(getDecl()->getDeclName(), getLocation(), DNLoc);
    }
  
    SourceLocation getLocation() const { return DeclRefExprBits.Loc; }
    void setLocation(SourceLocation L) { DeclRefExprBits.Loc = L; }
    SourceLocation getBeginLoc() const LLVM_READONLY;
    SourceLocation getEndLoc() const LLVM_READONLY;
  
    /// Determine whether this declaration reference was preceded by a
    /// C++ nested-name-specifier, e.g., \c N::foo.
    bool hasQualifier() const { return DeclRefExprBits.HasQualifier; }
  
    /// 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 *getTrailingObjects<NestedNameSpecifierLoc>();
    }
  
    /// If the name was qualified, retrieves the nested-name-specifier
    /// that precedes the name. Otherwise, returns NULL.
    NestedNameSpecifier *getQualifier() const {
      return getQualifierLoc().getNestedNameSpecifier();
    }
  
    /// 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() ? *getTrailingObjects<NamedDecl *>() : D;
    }
  
    /// Get the NamedDecl through which this reference occurred.
    /// See non-const variant.
    const NamedDecl *getFoundDecl() const {
      return hasFoundDecl() ? *getTrailingObjects<NamedDecl *>() : D;
    }
  
    bool hasTemplateKWAndArgsInfo() const {
      return DeclRefExprBits.HasTemplateKWAndArgsInfo;
    }
  
    /// Retrieve the location of the template keyword preceding
    /// this name, if any.
    SourceLocation getTemplateKeywordLoc() const {
      if (!hasTemplateKWAndArgsInfo())
        return SourceLocation();
      return getTrailingObjects<ASTTemplateKWAndArgsInfo>()->TemplateKWLoc;
    }
  
    /// 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 getTrailingObjects<ASTTemplateKWAndArgsInfo>()->LAngleLoc;
    }
  
    /// 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 getTrailingObjects<ASTTemplateKWAndArgsInfo>()->RAngleLoc;
    }
  
    /// Determines whether the name in this declaration reference
    /// was preceded by the template keyword.
    bool hasTemplateKeyword() const { return getTemplateKeywordLoc().isValid(); }
  
    /// Determines whether this declaration reference was followed by an
    /// explicit template argument list.
    bool hasExplicitTemplateArgs() const { return getLAngleLoc().isValid(); }
  
    /// Copies the template arguments (if present) into the given
    /// structure.
    void copyTemplateArgumentsInto(TemplateArgumentListInfo &List) const {
      if (hasExplicitTemplateArgs())
        getTrailingObjects<ASTTemplateKWAndArgsInfo>()->copyInto(
            getTrailingObjects<TemplateArgumentLoc>(), List);
    }
  
    /// Retrieve the template arguments provided as part of this
    /// template-id.
    const TemplateArgumentLoc *getTemplateArgs() const {
      if (!hasExplicitTemplateArgs())
        return nullptr;
      return getTrailingObjects<TemplateArgumentLoc>();
    }
  
    /// Retrieve the number of template arguments provided as part of this
    /// template-id.
    unsigned getNumTemplateArgs() const {
      if (!hasExplicitTemplateArgs())
        return 0;
      return getTrailingObjects<ASTTemplateKWAndArgsInfo>()->NumTemplateArgs;
    }
  
    ArrayRef<TemplateArgumentLoc> template_arguments() const {
      return {getTemplateArgs(), getNumTemplateArgs()};
    }
  
    /// 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;
    }
    /// 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;
    }
  
    /// Is this expression a non-odr-use reference, and if so, why?
    NonOdrUseReason isNonOdrUse() const {
      return static_cast<NonOdrUseReason>(DeclRefExprBits.NonOdrUseReason);
    }
  
    /// Does this DeclRefExpr refer to an enclosing local or a captured
    /// variable?
    bool refersToEnclosingVariableOrCapture() const {
      return DeclRefExprBits.RefersToEnclosingVariableOrCapture;
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == DeclRefExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
  
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  /// 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 &) = delete;
    void operator=(const APNumericStorage &) = delete;
  
  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;
  
    /// 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);
  
    /// 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);
    /// Returns a new empty integer literal.
    static IntegerLiteral *Create(const ASTContext &C, EmptyShell Empty);
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return Loc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return Loc; }
  
    /// 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(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  class FixedPointLiteral : public Expr, public APIntStorage {
    SourceLocation Loc;
    unsigned Scale;
  
    /// \brief Construct an empty fixed-point literal.
    explicit FixedPointLiteral(EmptyShell Empty)
        : Expr(FixedPointLiteralClass, Empty) {}
  
   public:
    FixedPointLiteral(const ASTContext &C, const llvm::APInt &V, QualType type,
                      SourceLocation l, unsigned Scale);
  
    // Store the int as is without any bit shifting.
    static FixedPointLiteral *CreateFromRawInt(const ASTContext &C,
                                               const llvm::APInt &V,
                                               QualType type, SourceLocation l,
                                               unsigned Scale);
  
    /// Returns an empty fixed-point literal.
    static FixedPointLiteral *Create(const ASTContext &C, EmptyShell Empty);
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return Loc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return Loc; }
  
    /// \brief Retrieve the location of the literal.
    SourceLocation getLocation() const { return Loc; }
  
    void setLocation(SourceLocation Location) { Loc = Location; }
  
    unsigned getScale() const { return Scale; }
    void setScale(unsigned S) { Scale = S; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == FixedPointLiteralClass;
    }
  
    std::string getValueAsString(unsigned Radix) const;
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  class CharacterLiteral : public Expr {
  public:
    enum CharacterKind {
      Ascii,
      Wide,
      UTF8,
      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_PRValue, OK_Ordinary),
          Value(value), Loc(l) {
      CharacterLiteralBits.Kind = kind;
      setDependence(ExprDependence::None);
    }
  
    /// 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 getBeginLoc() const LLVM_READONLY { return Loc; }
    SourceLocation getEndLoc() 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;
    }
  
    static void print(unsigned val, CharacterKind Kind, raw_ostream &OS);
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  class FloatingLiteral : public Expr, private APFloatStorage {
    SourceLocation Loc;
  
    FloatingLiteral(const ASTContext &C, const llvm::APFloat &V, bool isexact,
                    QualType Type, SourceLocation L);
  
    /// 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.
    llvm::APFloatBase::Semantics getRawSemantics() const {
      return static_cast<llvm::APFloatBase::Semantics>(
          FloatingLiteralBits.Semantics);
    }
  
    /// Set the raw enumeration value representing the floating-point semantics of
    /// this literal (32-bit IEEE, x87, ...), suitable for serialisation.
    void setRawSemantics(llvm::APFloatBase::Semantics Sem) {
      FloatingLiteralBits.Semantics = Sem;
    }
  
    /// Return the APFloat semantics this literal uses.
    const llvm::fltSemantics &getSemantics() const {
      return llvm::APFloatBase::EnumToSemantics(
          static_cast<llvm::APFloatBase::Semantics>(
              FloatingLiteralBits.Semantics));
    }
  
    /// Set the APFloat semantics this literal uses.
    void setSemantics(const llvm::fltSemantics &Sem) {
      FloatingLiteralBits.Semantics = llvm::APFloatBase::SemanticsToEnum(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 getBeginLoc() const LLVM_READONLY { return Loc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return Loc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == FloatingLiteralClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  /// 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_PRValue, OK_Ordinary), Val(val) {
      setDependence(ExprDependence::None);
    }
  
    /// 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 getBeginLoc() const LLVM_READONLY {
      return Val->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY { return Val->getEndLoc(); }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ImaginaryLiteralClass;
    }
  
    // Iterators
    child_range children() { return child_range(&Val, &Val+1); }
    const_child_range children() const {
      return const_child_range(&Val, &Val + 1);
    }
  };
  
  /// StringLiteral - This represents a string literal expression, e.g. "foo"
  /// or L"bar" (wide strings). The actual string data can be obtained with
  /// getBytes() and is NOT null-terminated. The length of the string data 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 final
      : public Expr,
        private llvm::TrailingObjects<StringLiteral, unsigned, SourceLocation,
                                      char> {
    friend class ASTStmtReader;
    friend TrailingObjects;
  
    /// StringLiteral is followed by several trailing objects. They are in order:
    ///
    /// * A single unsigned storing the length in characters of this string. The
    ///   length in bytes is this length times the width of a single character.
    ///   Always present and stored as a trailing objects because storing it in
    ///   StringLiteral would increase the size of StringLiteral by sizeof(void *)
    ///   due to alignment requirements. If you add some data to StringLiteral,
    ///   consider moving it inside StringLiteral.
    ///
    /// * An array of getNumConcatenated() SourceLocation, one for each of the
    ///   token this string is made of.
    ///
    /// * An array of getByteLength() char used to store the string data.
  
  public:
    enum StringKind { Ascii, Wide, UTF8, UTF16, UTF32 };
  
  private:
    unsigned numTrailingObjects(OverloadToken<unsigned>) const { return 1; }
    unsigned numTrailingObjects(OverloadToken<SourceLocation>) const {
      return getNumConcatenated();
    }
  
    unsigned numTrailingObjects(OverloadToken<char>) const {
      return getByteLength();
    }
  
    char *getStrDataAsChar() { return getTrailingObjects<char>(); }
    const char *getStrDataAsChar() const { return getTrailingObjects<char>(); }
  
    const uint16_t *getStrDataAsUInt16() const {
      return reinterpret_cast<const uint16_t *>(getTrailingObjects<char>());
    }
  
    const uint32_t *getStrDataAsUInt32() const {
      return reinterpret_cast<const uint32_t *>(getTrailingObjects<char>());
    }
  
    /// Build a string literal.
    StringLiteral(const ASTContext &Ctx, StringRef Str, StringKind Kind,
                  bool Pascal, QualType Ty, const SourceLocation *Loc,
                  unsigned NumConcatenated);
  
    /// Build an empty string literal.
    StringLiteral(EmptyShell Empty, unsigned NumConcatenated, unsigned Length,
                  unsigned CharByteWidth);
  
    /// Map a target and string kind to the appropriate character width.
    static unsigned mapCharByteWidth(TargetInfo const &Target, StringKind SK);
  
    /// Set one of the string literal token.
    void setStrTokenLoc(unsigned TokNum, SourceLocation L) {
      assert(TokNum < getNumConcatenated() && "Invalid tok number");
      getTrailingObjects<SourceLocation>()[TokNum] = L;
    }
  
  public:
    /// This is the "fully general" constructor that allows representation of
    /// strings formed from multiple concatenated tokens.
    static StringLiteral *Create(const ASTContext &Ctx, StringRef Str,
                                 StringKind Kind, bool Pascal, QualType Ty,
                                 const SourceLocation *Loc,
                                 unsigned NumConcatenated);
  
    /// Simple constructor for string literals made from one token.
    static StringLiteral *Create(const ASTContext &Ctx, StringRef Str,
                                 StringKind Kind, bool Pascal, QualType Ty,
                                 SourceLocation Loc) {
      return Create(Ctx, Str, Kind, Pascal, Ty, &Loc, 1);
    }
  
    /// Construct an empty string literal.
    static StringLiteral *CreateEmpty(const ASTContext &Ctx,
                                      unsigned NumConcatenated, unsigned Length,
                                      unsigned CharByteWidth);
  
    StringRef getString() const {
      assert(getCharByteWidth() == 1 &&
             "This function is used in places that assume strings use char");
      return StringRef(getStrDataAsChar(), 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.
      return StringRef(getStrDataAsChar(), getByteLength());
    }
  
    void outputString(raw_ostream &OS) const;
  
    uint32_t getCodeUnit(size_t i) const {
      assert(i < getLength() && "out of bounds access");
      switch (getCharByteWidth()) {
      case 1:
        return static_cast<unsigned char>(getStrDataAsChar()[i]);
      case 2:
        return getStrDataAsUInt16()[i];
      case 4:
        return getStrDataAsUInt32()[i];
      }
      llvm_unreachable("Unsupported character width!");
    }
  
    unsigned getByteLength() const { return getCharByteWidth() * getLength(); }
    unsigned getLength() const { return *getTrailingObjects<unsigned>(); }
    unsigned getCharByteWidth() const { return StringLiteralBits.CharByteWidth; }
  
    StringKind getKind() const {
      return static_cast<StringKind>(StringLiteralBits.Kind);
    }
  
    bool isAscii() const { return getKind() == Ascii; }
    bool isWide() const { return getKind() == Wide; }
    bool isUTF8() const { return getKind() == UTF8; }
    bool isUTF16() const { return getKind() == UTF16; }
    bool isUTF32() const { return getKind() == UTF32; }
    bool isPascal() const { return StringLiteralBits.IsPascal; }
  
    bool containsNonAscii() const {
      for (auto c : getString())
        if (!isASCII(c))
          return true;
      return false;
    }
  
    bool containsNonAsciiOrNull() const {
      for (auto c : getString())
        if (!isASCII(c) || !c)
          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 StringLiteralBits.NumConcatenated;
    }
  
    /// Get one of the string literal token.
    SourceLocation getStrTokenLoc(unsigned TokNum) const {
      assert(TokNum < getNumConcatenated() && "Invalid tok number");
      return getTrailingObjects<SourceLocation>()[TokNum];
    }
  
    /// 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,
                      unsigned *StartToken = nullptr,
                      unsigned *StartTokenByteOffset = nullptr) const;
  
    typedef const SourceLocation *tokloc_iterator;
  
    tokloc_iterator tokloc_begin() const {
      return getTrailingObjects<SourceLocation>();
    }
  
    tokloc_iterator tokloc_end() const {
      return getTrailingObjects<SourceLocation>() + getNumConcatenated();
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return *tokloc_begin(); }
    SourceLocation getEndLoc() const LLVM_READONLY { return *(tokloc_end() - 1); }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == StringLiteralClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  /// [C99 6.4.2.2] - A predefined identifier such as __func__.
  class PredefinedExpr final
      : public Expr,
        private llvm::TrailingObjects<PredefinedExpr, Stmt *> {
    friend class ASTStmtReader;
    friend TrailingObjects;
  
    // PredefinedExpr is optionally followed by a single trailing
    // "Stmt *" for the predefined identifier. It is present if and only if
    // hasFunctionName() is true and is always a "StringLiteral *".
  
  public:
    enum IdentKind {
      Func,
      Function,
      LFunction, // Same as Function, but as wide string.
      FuncDName,
      FuncSig,
      LFuncSig, // Same as FuncSig, but as as wide string
      PrettyFunction,
      /// The same as PrettyFunction, except that the
      /// 'virtual' keyword is omitted for virtual member functions.
      PrettyFunctionNoVirtual
    };
  
  private:
    PredefinedExpr(SourceLocation L, QualType FNTy, IdentKind IK,
                   StringLiteral *SL);
  
    explicit PredefinedExpr(EmptyShell Empty, bool HasFunctionName);
  
    /// True if this PredefinedExpr has storage for a function name.
    bool hasFunctionName() const { return PredefinedExprBits.HasFunctionName; }
  
    void setFunctionName(StringLiteral *SL) {
      assert(hasFunctionName() &&
             "This PredefinedExpr has no storage for a function name!");
      *getTrailingObjects<Stmt *>() = SL;
    }
  
  public:
    /// Create a PredefinedExpr.
    static PredefinedExpr *Create(const ASTContext &Ctx, SourceLocation L,
                                  QualType FNTy, IdentKind IK, StringLiteral *SL);
  
    /// Create an empty PredefinedExpr.
    static PredefinedExpr *CreateEmpty(const ASTContext &Ctx,
                                       bool HasFunctionName);
  
    IdentKind getIdentKind() const {
      return static_cast<IdentKind>(PredefinedExprBits.Kind);
    }
  
    SourceLocation getLocation() const { return PredefinedExprBits.Loc; }
    void setLocation(SourceLocation L) { PredefinedExprBits.Loc = L; }
  
    StringLiteral *getFunctionName() {
      return hasFunctionName()
                 ? static_cast<StringLiteral *>(*getTrailingObjects<Stmt *>())
                 : nullptr;
    }
  
    const StringLiteral *getFunctionName() const {
      return hasFunctionName()
                 ? static_cast<StringLiteral *>(*getTrailingObjects<Stmt *>())
                 : nullptr;
    }
  
    static StringRef getIdentKindName(IdentKind IK);
    StringRef getIdentKindName() const {
      return getIdentKindName(getIdentKind());
    }
  
    static std::string ComputeName(IdentKind IK, const Decl *CurrentDecl);
  
    SourceLocation getBeginLoc() const { return getLocation(); }
    SourceLocation getEndLoc() const { return getLocation(); }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == PredefinedExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(getTrailingObjects<Stmt *>(),
                         getTrailingObjects<Stmt *>() + hasFunctionName());
    }
  
    const_child_range children() const {
      return const_child_range(getTrailingObjects<Stmt *>(),
                               getTrailingObjects<Stmt *>() + hasFunctionName());
    }
  };
  
  // This represents a use of the __builtin_sycl_unique_stable_name, which takes a
  // type-id, and at CodeGen time emits a unique string representation of the
  // type in a way that permits us to properly encode information about the SYCL
  // kernels.
  class SYCLUniqueStableNameExpr final : public Expr {
    friend class ASTStmtReader;
    SourceLocation OpLoc, LParen, RParen;
    TypeSourceInfo *TypeInfo;
  
    SYCLUniqueStableNameExpr(EmptyShell Empty, QualType ResultTy);
    SYCLUniqueStableNameExpr(SourceLocation OpLoc, SourceLocation LParen,
                             SourceLocation RParen, QualType ResultTy,
                             TypeSourceInfo *TSI);
  
    void setTypeSourceInfo(TypeSourceInfo *Ty) { TypeInfo = Ty; }
  
    void setLocation(SourceLocation L) { OpLoc = L; }
    void setLParenLocation(SourceLocation L) { LParen = L; }
    void setRParenLocation(SourceLocation L) { RParen = L; }
  
  public:
    TypeSourceInfo *getTypeSourceInfo() { return TypeInfo; }
  
    const TypeSourceInfo *getTypeSourceInfo() const { return TypeInfo; }
  
    static SYCLUniqueStableNameExpr *
    Create(const ASTContext &Ctx, SourceLocation OpLoc, SourceLocation LParen,
           SourceLocation RParen, TypeSourceInfo *TSI);
  
    static SYCLUniqueStableNameExpr *CreateEmpty(const ASTContext &Ctx);
  
    SourceLocation getBeginLoc() const { return getLocation(); }
    SourceLocation getEndLoc() const { return RParen; }
    SourceLocation getLocation() const { return OpLoc; }
    SourceLocation getLParenLocation() const { return LParen; }
    SourceLocation getRParenLocation() const { return RParen; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == SYCLUniqueStableNameExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
  
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  
    // Convenience function to generate the name of the currently stored type.
    std::string ComputeName(ASTContext &Context) const;
  
    // Get the generated name of the type.  Note that this only works after all
    // kernels have been instantiated.
    static std::string ComputeName(ASTContext &Context, QualType Ty);
  };
  
  /// 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()),
          L(l), R(r), Val(val) {
      setDependence(computeDependence(this));
    }
  
    /// 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 getBeginLoc() const LLVM_READONLY { return L; }
    SourceLocation getEndLoc() const LLVM_READONLY { return R; }
  
    /// Get the location of the left parentheses '('.
    SourceLocation getLParen() const { return L; }
    void setLParen(SourceLocation Loc) { L = Loc; }
  
    /// 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); }
    const_child_range children() const {
      return const_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 final
      : public Expr,
        private llvm::TrailingObjects<UnaryOperator, FPOptionsOverride> {
    Stmt *Val;
  
    size_t numTrailingObjects(OverloadToken<FPOptionsOverride>) const {
      return UnaryOperatorBits.HasFPFeatures ? 1 : 0;
    }
  
    FPOptionsOverride &getTrailingFPFeatures() {
      assert(UnaryOperatorBits.HasFPFeatures);
      return *getTrailingObjects<FPOptionsOverride>();
    }
  
    const FPOptionsOverride &getTrailingFPFeatures() const {
      assert(UnaryOperatorBits.HasFPFeatures);
      return *getTrailingObjects<FPOptionsOverride>();
    }
  
  public:
    typedef UnaryOperatorKind Opcode;
  
  protected:
    UnaryOperator(const ASTContext &Ctx, Expr *input, Opcode opc, QualType type,
                  ExprValueKind VK, ExprObjectKind OK, SourceLocation l,
                  bool CanOverflow, FPOptionsOverride FPFeatures);
  
    /// Build an empty unary operator.
    explicit UnaryOperator(bool HasFPFeatures, EmptyShell Empty)
        : Expr(UnaryOperatorClass, Empty) {
      UnaryOperatorBits.Opc = UO_AddrOf;
      UnaryOperatorBits.HasFPFeatures = HasFPFeatures;
    }
  
  public:
    static UnaryOperator *CreateEmpty(const ASTContext &C, bool hasFPFeatures);
  
    static UnaryOperator *Create(const ASTContext &C, Expr *input, Opcode opc,
                                 QualType type, ExprValueKind VK,
                                 ExprObjectKind OK, SourceLocation l,
                                 bool CanOverflow, FPOptionsOverride FPFeatures);
  
    Opcode getOpcode() const {
      return static_cast<Opcode>(UnaryOperatorBits.Opc);
    }
    void setOpcode(Opcode Opc) { UnaryOperatorBits.Opc = Opc; }
  
    Expr *getSubExpr() const { return cast<Expr>(Val); }
    void setSubExpr(Expr *E) { Val = E; }
  
    /// getOperatorLoc - Return the location of the operator.
    SourceLocation getOperatorLoc() const { return UnaryOperatorBits.Loc; }
    void setOperatorLoc(SourceLocation L) { UnaryOperatorBits.Loc = L; }
  
    /// Returns true if the unary operator can cause an overflow. For instance,
    ///   signed int i = INT_MAX; i++;
    ///   signed char c = CHAR_MAX; c++;
    /// Due to integer promotions, c++ is promoted to an int before the postfix
    /// increment, and the result is an int that cannot overflow. However, i++
    /// can overflow.
    bool canOverflow() const { return UnaryOperatorBits.CanOverflow; }
    void setCanOverflow(bool C) { UnaryOperatorBits.CanOverflow = C; }
  
    // Get the FP contractability status of this operator. Only meaningful for
    // operations on floating point types.
    bool isFPContractableWithinStatement(const LangOptions &LO) const {
      return getFPFeaturesInEffect(LO).allowFPContractWithinStatement();
    }
  
    // Get the FENV_ACCESS status of this operator. Only meaningful for
    // operations on floating point types.
    bool isFEnvAccessOn(const LangOptions &LO) const {
      return getFPFeaturesInEffect(LO).getAllowFEnvAccess();
    }
  
    /// 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);
  
    /// Retrieve the unary opcode that corresponds to the given
    /// overloaded operator.
    static Opcode getOverloadedOpcode(OverloadedOperatorKind OO, bool Postfix);
  
    /// Retrieve the overloaded operator kind that corresponds to
    /// the given unary opcode.
    static OverloadedOperatorKind getOverloadedOperator(Opcode Opc);
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return isPostfix() ? Val->getBeginLoc() : getOperatorLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return isPostfix() ? getOperatorLoc() : Val->getEndLoc();
    }
    SourceLocation getExprLoc() const { return getOperatorLoc(); }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == UnaryOperatorClass;
    }
  
    // Iterators
    child_range children() { return child_range(&Val, &Val+1); }
    const_child_range children() const {
      return const_child_range(&Val, &Val + 1);
    }
  
    /// Is FPFeatures in Trailing Storage?
    bool hasStoredFPFeatures() const { return UnaryOperatorBits.HasFPFeatures; }
  
    /// Get FPFeatures from trailing storage.
    FPOptionsOverride getStoredFPFeatures() const {
      return getTrailingFPFeatures();
    }
  
  protected:
    /// Set FPFeatures in trailing storage, used only by Serialization
    void setStoredFPFeatures(FPOptionsOverride F) { getTrailingFPFeatures() = F; }
  
  public:
    // Get the FP features status of this operator. Only meaningful for
    // operations on floating point types.
    FPOptions getFPFeaturesInEffect(const LangOptions &LO) const {
      if (UnaryOperatorBits.HasFPFeatures)
        return getStoredFPFeatures().applyOverrides(LO);
      return FPOptions::defaultWithoutTrailingStorage(LO);
    }
    FPOptionsOverride getFPOptionsOverride() const {
      if (UnaryOperatorBits.HasFPFeatures)
        return getStoredFPFeatures();
      return FPOptionsOverride();
    }
  
    friend TrailingObjects;
    friend class ASTReader;
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
  };
  
  /// Helper class for OffsetOfExpr.
  
  // __builtin_offsetof(type, identifier(.identifier|[expr])*)
  class OffsetOfNode {
  public:
    /// The kind of offsetof node we have.
    enum Kind {
      /// An index into an array.
      Array = 0x00,
      /// A field.
      Field = 0x01,
      /// A field in a dependent type, known only by its name.
      Identifier = 0x02,
      /// 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 };
  
    /// The source range that covers this part of the designator.
    SourceRange Range;
  
    /// 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:
    /// Create an offsetof node that refers to an array element.
    OffsetOfNode(SourceLocation LBracketLoc, unsigned Index,
                 SourceLocation RBracketLoc)
        : Range(LBracketLoc, RBracketLoc), Data((Index << 2) | Array) {}
  
    /// 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) {}
  
    /// 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) {}
  
    /// 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) {}
  
    /// Determine what kind of offsetof node this is.
    Kind getKind() const { return static_cast<Kind>(Data & Mask); }
  
    /// For an array element node, returns the index into the array
    /// of expressions.
    unsigned getArrayExprIndex() const {
      assert(getKind() == Array);
      return Data >> 2;
    }
  
    /// For a field offsetof node, returns the field.
    FieldDecl *getField() const {
      assert(getKind() == Field);
      return reinterpret_cast<FieldDecl *>(Data & ~(uintptr_t)Mask);
    }
  
    /// For a field or identifier offsetof node, returns the name of
    /// the field.
    IdentifierInfo *getFieldName() const;
  
    /// For a base class node, returns the base specifier.
    CXXBaseSpecifier *getBase() const {
      assert(getKind() == Base);
      return reinterpret_cast<CXXBaseSpecifier *>(Data & ~(uintptr_t)Mask);
    }
  
    /// 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 getBeginLoc() const LLVM_READONLY { return Range.getBegin(); }
    SourceLocation getEndLoc() const LLVM_READONLY { return Range.getEnd(); }
  };
  
  /// 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 final
      : public Expr,
        private llvm::TrailingObjects<OffsetOfExpr, OffsetOfNode, Expr *> {
    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;
  
    size_t numTrailingObjects(OverloadToken<OffsetOfNode>) const {
      return NumComps;
    }
  
    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; }
  
    /// 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 getTrailingObjects<OffsetOfNode>()[Idx];
    }
  
    void setComponent(unsigned Idx, OffsetOfNode ON) {
      assert(Idx < NumComps && "Subscript out of range");
      getTrailingObjects<OffsetOfNode>()[Idx] = ON;
    }
  
    unsigned getNumComponents() const {
      return NumComps;
    }
  
    Expr* getIndexExpr(unsigned Idx) {
      assert(Idx < NumExprs && "Subscript out of range");
      return getTrailingObjects<Expr *>()[Idx];
    }
  
    const Expr *getIndexExpr(unsigned Idx) const {
      assert(Idx < NumExprs && "Subscript out of range");
      return getTrailingObjects<Expr *>()[Idx];
    }
  
    void setIndexExpr(unsigned Idx, Expr* E) {
      assert(Idx < NumComps && "Subscript out of range");
      getTrailingObjects<Expr *>()[Idx] = E;
    }
  
    unsigned getNumExpressions() const {
      return NumExprs;
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return OperatorLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == OffsetOfExprClass;
    }
  
    // Iterators
    child_range children() {
      Stmt **begin = reinterpret_cast<Stmt **>(getTrailingObjects<Expr *>());
      return child_range(begin, begin + NumExprs);
    }
    const_child_range children() const {
      Stmt *const *begin =
          reinterpret_cast<Stmt *const *>(getTrailingObjects<Expr *>());
      return const_child_range(begin, begin + NumExprs);
    }
    friend TrailingObjects;
  };
  
  /// 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_PRValue,
               OK_Ordinary),
          OpLoc(op), RParenLoc(rp) {
      assert(ExprKind <= UETT_Last && "invalid enum value!");
      UnaryExprOrTypeTraitExprBits.Kind = ExprKind;
      assert(static_cast<unsigned>(ExprKind) ==
                 UnaryExprOrTypeTraitExprBits.Kind &&
             "UnaryExprOrTypeTraitExprBits.Kind overflow!");
      UnaryExprOrTypeTraitExprBits.IsType = true;
      Argument.Ty = TInfo;
      setDependence(computeDependence(this));
    }
  
    UnaryExprOrTypeTraitExpr(UnaryExprOrTypeTrait ExprKind, Expr *E,
                             QualType resultType, SourceLocation op,
                             SourceLocation rp);
  
    /// 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) {
      assert(K <= UETT_Last && "invalid enum value!");
      UnaryExprOrTypeTraitExprBits.Kind = K;
      assert(static_cast<unsigned>(K) == UnaryExprOrTypeTraitExprBits.Kind &&
             "UnaryExprOrTypeTraitExprBits.Kind overflow!");
    }
  
    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 getBeginLoc() const LLVM_READONLY { return OpLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == UnaryExprOrTypeTraitExprClass;
    }
  
    // Iterators
    child_range children();
    const_child_range children() const;
  };
  
  //===----------------------------------------------------------------------===//
  // Postfix Operators.
  //===----------------------------------------------------------------------===//
  
  /// ArraySubscriptExpr - [C99 6.5.2.1] Array Subscripting.
  class ArraySubscriptExpr : public Expr {
    enum { LHS, RHS, END_EXPR };
    Stmt *SubExprs[END_EXPR];
  
    bool lhsIsBase() const { return getRHS()->getType()->isIntegerType(); }
  
  public:
    ArraySubscriptExpr(Expr *lhs, Expr *rhs, QualType t, ExprValueKind VK,
                       ExprObjectKind OK, SourceLocation rbracketloc)
        : Expr(ArraySubscriptExprClass, t, VK, OK) {
      SubExprs[LHS] = lhs;
      SubExprs[RHS] = rhs;
      ArrayOrMatrixSubscriptExprBits.RBracketLoc = rbracketloc;
      setDependence(computeDependence(this));
    }
  
    /// 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 lhsIsBase() ? getLHS() : getRHS(); }
    const Expr *getBase() const { return lhsIsBase() ? getLHS() : getRHS(); }
  
    Expr *getIdx() { return lhsIsBase() ? getRHS() : getLHS(); }
    const Expr *getIdx() const { return lhsIsBase() ? getRHS() : getLHS(); }
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getLHS()->getBeginLoc();
    }
    SourceLocation getEndLoc() const { return getRBracketLoc(); }
  
    SourceLocation getRBracketLoc() const {
      return ArrayOrMatrixSubscriptExprBits.RBracketLoc;
    }
    void setRBracketLoc(SourceLocation L) {
      ArrayOrMatrixSubscriptExprBits.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);
    }
    const_child_range children() const {
      return const_child_range(&SubExprs[0], &SubExprs[0] + END_EXPR);
    }
  };
  
  /// MatrixSubscriptExpr - Matrix subscript expression for the MatrixType
  /// extension.
  /// MatrixSubscriptExpr can be either incomplete (only Base and RowIdx are set
  /// so far, the type is IncompleteMatrixIdx) or complete (Base, RowIdx and
  /// ColumnIdx refer to valid expressions). Incomplete matrix expressions only
  /// exist during the initial construction of the AST.
  class MatrixSubscriptExpr : public Expr {
    enum { BASE, ROW_IDX, COLUMN_IDX, END_EXPR };
    Stmt *SubExprs[END_EXPR];
  
  public:
    MatrixSubscriptExpr(Expr *Base, Expr *RowIdx, Expr *ColumnIdx, QualType T,
                        SourceLocation RBracketLoc)
        : Expr(MatrixSubscriptExprClass, T, Base->getValueKind(),
               OK_MatrixComponent) {
      SubExprs[BASE] = Base;
      SubExprs[ROW_IDX] = RowIdx;
      SubExprs[COLUMN_IDX] = ColumnIdx;
      ArrayOrMatrixSubscriptExprBits.RBracketLoc = RBracketLoc;
      setDependence(computeDependence(this));
    }
  
    /// Create an empty matrix subscript expression.
    explicit MatrixSubscriptExpr(EmptyShell Shell)
        : Expr(MatrixSubscriptExprClass, Shell) {}
  
    bool isIncomplete() const {
      bool IsIncomplete = hasPlaceholderType(BuiltinType::IncompleteMatrixIdx);
      assert((SubExprs[COLUMN_IDX] || IsIncomplete) &&
             "expressions without column index must be marked as incomplete");
      return IsIncomplete;
    }
    Expr *getBase() { return cast<Expr>(SubExprs[BASE]); }
    const Expr *getBase() const { return cast<Expr>(SubExprs[BASE]); }
    void setBase(Expr *E) { SubExprs[BASE] = E; }
  
    Expr *getRowIdx() { return cast<Expr>(SubExprs[ROW_IDX]); }
    const Expr *getRowIdx() const { return cast<Expr>(SubExprs[ROW_IDX]); }
    void setRowIdx(Expr *E) { SubExprs[ROW_IDX] = E; }
  
    Expr *getColumnIdx() { return cast_or_null<Expr>(SubExprs[COLUMN_IDX]); }
    const Expr *getColumnIdx() const {
      assert(!isIncomplete() &&
             "cannot get the column index of an incomplete expression");
      return cast<Expr>(SubExprs[COLUMN_IDX]);
    }
    void setColumnIdx(Expr *E) { SubExprs[COLUMN_IDX] = E; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getBase()->getBeginLoc();
    }
  
    SourceLocation getEndLoc() const { return getRBracketLoc(); }
  
    SourceLocation getExprLoc() const LLVM_READONLY {
      return getBase()->getExprLoc();
    }
  
    SourceLocation getRBracketLoc() const {
      return ArrayOrMatrixSubscriptExprBits.RBracketLoc;
    }
    void setRBracketLoc(SourceLocation L) {
      ArrayOrMatrixSubscriptExprBits.RBracketLoc = L;
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == MatrixSubscriptExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(&SubExprs[0], &SubExprs[0] + END_EXPR);
    }
    const_child_range children() const {
      return const_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 };
  
    /// The number of arguments in the call expression.
    unsigned NumArgs;
  
    /// The location of the right parenthese. This has a different meaning for
    /// the derived classes of CallExpr.
    SourceLocation RParenLoc;
  
    // CallExpr store some data in trailing objects. However since CallExpr
    // is used a base of other expression classes we cannot use
    // llvm::TrailingObjects. Instead we manually perform the pointer arithmetic
    // and casts.
    //
    // The trailing objects are in order:
    //
    // * A single "Stmt *" for the callee expression.
    //
    // * An array of getNumPreArgs() "Stmt *" for the pre-argument expressions.
    //
    // * An array of getNumArgs() "Stmt *" for the argument expressions.
    //
    // * An optional of type FPOptionsOverride.
    //
    // Note that we store the offset in bytes from the this pointer to the start
    // of the trailing objects. It would be perfectly possible to compute it
    // based on the dynamic kind of the CallExpr. However 1.) we have plenty of
    // space in the bit-fields of Stmt. 2.) It was benchmarked to be faster to
    // compute this once and then load the offset from the bit-fields of Stmt,
    // instead of re-computing the offset each time the trailing objects are
    // accessed.
  
    /// Return a pointer to the start of the trailing array of "Stmt *".
    Stmt **getTrailingStmts() {
      return reinterpret_cast<Stmt **>(reinterpret_cast<char *>(this) +
                                       CallExprBits.OffsetToTrailingObjects);
    }
    Stmt *const *getTrailingStmts() const {
      return const_cast<CallExpr *>(this)->getTrailingStmts();
    }
  
    /// Map a statement class to the appropriate offset in bytes from the
    /// this pointer to the trailing objects.
    static unsigned offsetToTrailingObjects(StmtClass SC);
  
    unsigned getSizeOfTrailingStmts() const {
      return (1 + getNumPreArgs() + getNumArgs()) * sizeof(Stmt *);
    }
  
    size_t getOffsetOfTrailingFPFeatures() const {
      assert(hasStoredFPFeatures());
      return CallExprBits.OffsetToTrailingObjects + getSizeOfTrailingStmts();
    }
  
  public:
    enum class ADLCallKind : bool { NotADL, UsesADL };
    static constexpr ADLCallKind NotADL = ADLCallKind::NotADL;
    static constexpr ADLCallKind UsesADL = ADLCallKind::UsesADL;
  
  protected:
    /// Build a call expression, assuming that appropriate storage has been
    /// allocated for the trailing objects.
    CallExpr(StmtClass SC, Expr *Fn, ArrayRef<Expr *> PreArgs,
             ArrayRef<Expr *> Args, QualType Ty, ExprValueKind VK,
             SourceLocation RParenLoc, FPOptionsOverride FPFeatures,
             unsigned MinNumArgs, ADLCallKind UsesADL);
  
    /// Build an empty call expression, for deserialization.
    CallExpr(StmtClass SC, unsigned NumPreArgs, unsigned NumArgs,
             bool hasFPFeatures, EmptyShell Empty);
  
    /// Return the size in bytes needed for the trailing objects.
    /// Used by the derived classes to allocate the right amount of storage.
    static unsigned sizeOfTrailingObjects(unsigned NumPreArgs, unsigned NumArgs,
                                          bool HasFPFeatures) {
      return (1 + NumPreArgs + NumArgs) * sizeof(Stmt *) +
             HasFPFeatures * sizeof(FPOptionsOverride);
    }
  
    Stmt *getPreArg(unsigned I) {
      assert(I < getNumPreArgs() && "Prearg access out of range!");
      return getTrailingStmts()[PREARGS_START + I];
    }
    const Stmt *getPreArg(unsigned I) const {
      assert(I < getNumPreArgs() && "Prearg access out of range!");
      return getTrailingStmts()[PREARGS_START + I];
    }
    void setPreArg(unsigned I, Stmt *PreArg) {
      assert(I < getNumPreArgs() && "Prearg access out of range!");
      getTrailingStmts()[PREARGS_START + I] = PreArg;
    }
  
    unsigned getNumPreArgs() const { return CallExprBits.NumPreArgs; }
  
    /// Return a pointer to the trailing FPOptions
    FPOptionsOverride *getTrailingFPFeatures() {
      assert(hasStoredFPFeatures());
      return reinterpret_cast<FPOptionsOverride *>(
          reinterpret_cast<char *>(this) + CallExprBits.OffsetToTrailingObjects +
          getSizeOfTrailingStmts());
    }
    const FPOptionsOverride *getTrailingFPFeatures() const {
      assert(hasStoredFPFeatures());
      return reinterpret_cast<const FPOptionsOverride *>(
          reinterpret_cast<const char *>(this) +
          CallExprBits.OffsetToTrailingObjects + getSizeOfTrailingStmts());
    }
  
  public:
    /// Create a call expression.
    /// \param Fn     The callee expression,
    /// \param Args   The argument array,
    /// \param Ty     The type of the call expression (which is *not* the return
    ///               type in general),
    /// \param VK     The value kind of the call expression (lvalue, rvalue, ...),
    /// \param RParenLoc  The location of the right parenthesis in the call
    ///                   expression.
    /// \param FPFeatures Floating-point features associated with the call,
    /// \param MinNumArgs Specifies the minimum number of arguments. The actual
    ///                   number of arguments will be the greater of Args.size()
    ///                   and MinNumArgs. This is used in a few places to allocate
    ///                   enough storage for the default arguments.
    /// \param UsesADL    Specifies whether the callee was found through
    ///                   argument-dependent lookup.
    ///
    /// Note that you can use CreateTemporary if you need a temporary call
    /// expression on the stack.
    static CallExpr *Create(const ASTContext &Ctx, Expr *Fn,
                            ArrayRef<Expr *> Args, QualType Ty, ExprValueKind VK,
                            SourceLocation RParenLoc,
                            FPOptionsOverride FPFeatures, unsigned MinNumArgs = 0,
                            ADLCallKind UsesADL = NotADL);
  
    /// Create a temporary call expression with no arguments in the memory
    /// pointed to by Mem. Mem must points to at least sizeof(CallExpr)
    /// + sizeof(Stmt *) bytes of storage, aligned to alignof(CallExpr):
    ///
    /// \code{.cpp}
    ///   alignas(CallExpr) char Buffer[sizeof(CallExpr) + sizeof(Stmt *)];
    ///   CallExpr *TheCall = CallExpr::CreateTemporary(Buffer, etc);
    /// \endcode
    static CallExpr *CreateTemporary(void *Mem, Expr *Fn, QualType Ty,
                                     ExprValueKind VK, SourceLocation RParenLoc,
                                     ADLCallKind UsesADL = NotADL);
  
    /// Create an empty call expression, for deserialization.
    static CallExpr *CreateEmpty(const ASTContext &Ctx, unsigned NumArgs,
                                 bool HasFPFeatures, EmptyShell Empty);
  
    Expr *getCallee() { return cast<Expr>(getTrailingStmts()[FN]); }
    const Expr *getCallee() const { return cast<Expr>(getTrailingStmts()[FN]); }
    void setCallee(Expr *F) { getTrailingStmts()[FN] = F; }
  
    ADLCallKind getADLCallKind() const {
      return static_cast<ADLCallKind>(CallExprBits.UsesADL);
    }
    void setADLCallKind(ADLCallKind V = UsesADL) {
      CallExprBits.UsesADL = static_cast<bool>(V);
    }
    bool usesADL() const { return getADLCallKind() == UsesADL; }
  
    bool hasStoredFPFeatures() const { return CallExprBits.HasFPFeatures; }
  
    Decl *getCalleeDecl() { return getCallee()->getReferencedDeclOfCallee(); }
    const Decl *getCalleeDecl() const {
      return getCallee()->getReferencedDeclOfCallee();
    }
  
    /// If the callee is a FunctionDecl, return it. Otherwise return null.
    FunctionDecl *getDirectCallee() {
      return dyn_cast_or_null<FunctionDecl>(getCalleeDecl());
    }
    const FunctionDecl *getDirectCallee() const {
      return dyn_cast_or_null<FunctionDecl>(getCalleeDecl());
    }
  
    /// getNumArgs - Return the number of actual arguments to this call.
    unsigned getNumArgs() const { return NumArgs; }
  
    /// Retrieve the call arguments.
    Expr **getArgs() {
      return reinterpret_cast<Expr **>(getTrailingStmts() + PREARGS_START +
                                       getNumPreArgs());
    }
    const Expr *const *getArgs() const {
      return reinterpret_cast<const Expr *const *>(
          getTrailingStmts() + PREARGS_START + getNumPreArgs());
    }
  
    /// getArg - Return the specified argument.
    Expr *getArg(unsigned Arg) {
      assert(Arg < getNumArgs() && "Arg access out of range!");
      return getArgs()[Arg];
    }
    const Expr *getArg(unsigned Arg) const {
      assert(Arg < getNumArgs() && "Arg access out of range!");
      return getArgs()[Arg];
    }
  
    /// setArg - Set the specified argument.
    /// ! the dependence bits might be stale after calling this setter, it is
    /// *caller*'s responsibility to recompute them by calling
    /// computeDependence().
    void setArg(unsigned Arg, Expr *ArgExpr) {
      assert(Arg < getNumArgs() && "Arg access out of range!");
      getArgs()[Arg] = ArgExpr;
    }
  
    /// Compute and set dependence bits.
    void computeDependence() {
      setDependence(clang::computeDependence(
          this, llvm::makeArrayRef(
                    reinterpret_cast<Expr **>(getTrailingStmts() + PREARGS_START),
                    getNumPreArgs())));
    }
  
    /// Reduce the number of arguments in this call expression. This is used for
    /// example during error recovery to drop extra arguments. There is no way
    /// to perform the opposite because: 1.) We don't track how much storage
    /// we have for the argument array 2.) This would potentially require growing
    /// the argument array, something we cannot support since the arguments are
    /// stored in a trailing array.
    void shrinkNumArgs(unsigned NewNumArgs) {
      assert((NewNumArgs <= getNumArgs()) &&
             "shrinkNumArgs cannot increase the number of arguments!");
      NumArgs = NewNumArgs;
    }
  
    /// Bluntly set a new number of arguments without doing any checks whatsoever.
    /// Only used during construction of a CallExpr in a few places in Sema.
    /// FIXME: Find a way to remove it.
    void setNumArgsUnsafe(unsigned NewNumArgs) { NumArgs = NewNumArgs; }
  
    typedef ExprIterator arg_iterator;
    typedef ConstExprIterator const_arg_iterator;
    typedef llvm::iterator_range<arg_iterator> arg_range;
    typedef llvm::iterator_range<const_arg_iterator> const_arg_range;
  
    arg_range arguments() { return arg_range(arg_begin(), arg_end()); }
    const_arg_range arguments() const {
      return const_arg_range(arg_begin(), arg_end());
    }
  
    arg_iterator arg_begin() {
      return getTrailingStmts() + PREARGS_START + getNumPreArgs();
    }
    arg_iterator arg_end() { return arg_begin() + getNumArgs(); }
  
    const_arg_iterator arg_begin() const {
      return getTrailingStmts() + PREARGS_START + getNumPreArgs();
    }
    const_arg_iterator arg_end() const { return arg_begin() + 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 llvm::makeArrayRef(getTrailingStmts(),
                                PREARGS_START + getNumPreArgs() + getNumArgs());
    }
  
    /// getNumCommas - Return the number of commas that must have been present in
    /// this function call.
    unsigned getNumCommas() const { return getNumArgs() ? getNumArgs() - 1 : 0; }
  
    /// Get FPOptionsOverride from trailing storage.
    FPOptionsOverride getStoredFPFeatures() const {
      assert(hasStoredFPFeatures());
      return *getTrailingFPFeatures();
    }
    /// Set FPOptionsOverride in trailing storage. Used only by Serialization.
    void setStoredFPFeatures(FPOptionsOverride F) {
      assert(hasStoredFPFeatures());
      *getTrailingFPFeatures() = F;
    }
  
    // Get the FP features status of this operator. Only meaningful for
    // operations on floating point types.
    FPOptions getFPFeaturesInEffect(const LangOptions &LO) const {
      if (hasStoredFPFeatures())
        return getStoredFPFeatures().applyOverrides(LO);
      return FPOptions::defaultWithoutTrailingStorage(LO);
    }
  
    FPOptionsOverride getFPFeatures() const {
      if (hasStoredFPFeatures())
        return getStoredFPFeatures();
      return FPOptionsOverride();
    }
  
    /// getBuiltinCallee - If this is a call to a builtin, return the builtin ID
    /// of the callee. If not, return 0.
    unsigned getBuiltinCallee() const;
  
    /// Returns \c true if this is a call to a builtin which does not
    /// evaluate side-effects within its arguments.
    bool isUnevaluatedBuiltinCall(const 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 ASTContext &Ctx) const;
  
    /// Returns the WarnUnusedResultAttr that is either declared on the called
    /// function, or its return type declaration.
    const Attr *getUnusedResultAttr(const ASTContext &Ctx) const;
  
    /// Returns true if this call expression should warn on unused results.
    bool hasUnusedResultAttr(const ASTContext &Ctx) const {
      return getUnusedResultAttr(Ctx) != nullptr;
    }
  
    SourceLocation getRParenLoc() const { return RParenLoc; }
    void setRParenLoc(SourceLocation L) { RParenLoc = L; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY;
    SourceLocation getEndLoc() const LLVM_READONLY;
  
    /// Return true if this is a call to __assume() or __builtin_assume() with
    /// a non-value-dependent constant parameter evaluating as false.
    bool isBuiltinAssumeFalse(const ASTContext &Ctx) const;
  
    /// Used by Sema to implement MSVC-compatible delayed name lookup.
    /// (Usually Exprs themselves should set dependence).
    void markDependentForPostponedNameLookup() {
      setDependence(getDependence() | ExprDependence::TypeValueInstantiation);
    }
  
    bool isCallToStdMove() const {
      const FunctionDecl *FD = getDirectCallee();
      return getNumArgs() == 1 && FD && FD->isInStdNamespace() &&
             FD->getIdentifier() && FD->getIdentifier()->isStr("move");
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() >= firstCallExprConstant &&
             T->getStmtClass() <= lastCallExprConstant;
    }
  
    // Iterators
    child_range children() {
      return child_range(getTrailingStmts(), getTrailingStmts() + PREARGS_START +
                                                 getNumPreArgs() + getNumArgs());
    }
  
    const_child_range children() const {
      return const_child_range(getTrailingStmts(),
                               getTrailingStmts() + PREARGS_START +
                                   getNumPreArgs() + getNumArgs());
    }
  };
  
  /// Extra data stored in some MemberExpr objects.
  struct MemberExprNameQualifier {
    /// The nested-name-specifier that qualifies the name, including
    /// source-location information.
    NestedNameSpecifierLoc QualifierLoc;
  
    /// The DeclAccessPair through which the MemberDecl was found due to
    /// name qualifiers.
    DeclAccessPair FoundDecl;
  };
  
  /// MemberExpr - [C99 6.5.2.3] Structure and Union Members.  X->F and X.F.
  ///
  class MemberExpr final
      : public Expr,
        private llvm::TrailingObjects<MemberExpr, MemberExprNameQualifier,
                                      ASTTemplateKWAndArgsInfo,
                                      TemplateArgumentLoc> {
    friend class ASTReader;
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
    friend TrailingObjects;
  
    /// 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;
  
    size_t numTrailingObjects(OverloadToken<MemberExprNameQualifier>) const {
      return hasQualifierOrFoundDecl();
    }
  
    size_t numTrailingObjects(OverloadToken<ASTTemplateKWAndArgsInfo>) const {
      return hasTemplateKWAndArgsInfo();
    }
  
    bool hasQualifierOrFoundDecl() const {
      return MemberExprBits.HasQualifierOrFoundDecl;
    }
  
    bool hasTemplateKWAndArgsInfo() const {
      return MemberExprBits.HasTemplateKWAndArgsInfo;
    }
  
    MemberExpr(Expr *Base, bool IsArrow, SourceLocation OperatorLoc,
               ValueDecl *MemberDecl, const DeclarationNameInfo &NameInfo,
               QualType T, ExprValueKind VK, ExprObjectKind OK,
               NonOdrUseReason NOUR);
    MemberExpr(EmptyShell Empty)
        : Expr(MemberExprClass, Empty), Base(), MemberDecl() {}
  
  public:
    static MemberExpr *Create(const ASTContext &C, Expr *Base, bool IsArrow,
                              SourceLocation OperatorLoc,
                              NestedNameSpecifierLoc QualifierLoc,
                              SourceLocation TemplateKWLoc, ValueDecl *MemberDecl,
                              DeclAccessPair FoundDecl,
                              DeclarationNameInfo MemberNameInfo,
                              const TemplateArgumentListInfo *TemplateArgs,
                              QualType T, ExprValueKind VK, ExprObjectKind OK,
                              NonOdrUseReason NOUR);
  
    /// Create an implicit MemberExpr, with no location, qualifier, template
    /// arguments, and so on. Suitable only for non-static member access.
    static MemberExpr *CreateImplicit(const ASTContext &C, Expr *Base,
                                      bool IsArrow, ValueDecl *MemberDecl,
                                      QualType T, ExprValueKind VK,
                                      ExprObjectKind OK) {
      return Create(C, Base, IsArrow, SourceLocation(), NestedNameSpecifierLoc(),
                    SourceLocation(), MemberDecl,
                    DeclAccessPair::make(MemberDecl, MemberDecl->getAccess()),
                    DeclarationNameInfo(), nullptr, T, VK, OK, NOUR_None);
    }
  
    static MemberExpr *CreateEmpty(const ASTContext &Context, bool HasQualifier,
                                   bool HasFoundDecl,
                                   bool HasTemplateKWAndArgsInfo,
                                   unsigned NumTemplateArgs);
  
    void setBase(Expr *E) { Base = E; }
    Expr *getBase() const { return cast<Expr>(Base); }
  
    /// Retrieve the member declaration to which this expression refers.
    ///
    /// The returned declaration will be a FieldDecl or (in C++) a VarDecl (for
    /// static data members), a CXXMethodDecl, or an EnumConstantDecl.
    ValueDecl *getMemberDecl() const { return MemberDecl; }
    void setMemberDecl(ValueDecl *D);
  
    /// Retrieves the declaration found by lookup.
    DeclAccessPair getFoundDecl() const {
      if (!hasQualifierOrFoundDecl())
        return DeclAccessPair::make(getMemberDecl(),
                                    getMemberDecl()->getAccess());
      return getTrailingObjects<MemberExprNameQualifier>()->FoundDecl;
    }
  
    /// 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; }
  
    /// If the member name was qualified, retrieves the
    /// nested-name-specifier that precedes the member name, with source-location
    /// information.
    NestedNameSpecifierLoc getQualifierLoc() const {
      if (!hasQualifierOrFoundDecl())
        return NestedNameSpecifierLoc();
      return getTrailingObjects<MemberExprNameQualifier>()->QualifierLoc;
    }
  
    /// If the member name was qualified, retrieves the
    /// nested-name-specifier that precedes the member name. Otherwise, returns
    /// NULL.
    NestedNameSpecifier *getQualifier() const {
      return getQualifierLoc().getNestedNameSpecifier();
    }
  
    /// Retrieve the location of the template keyword preceding
    /// the member name, if any.
    SourceLocation getTemplateKeywordLoc() const {
      if (!hasTemplateKWAndArgsInfo())
        return SourceLocation();
      return getTrailingObjects<ASTTemplateKWAndArgsInfo>()->TemplateKWLoc;
    }
  
    /// 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 getTrailingObjects<ASTTemplateKWAndArgsInfo>()->LAngleLoc;
    }
  
    /// 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 getTrailingObjects<ASTTemplateKWAndArgsInfo>()->RAngleLoc;
    }
  
    /// Determines whether the member name was preceded by the template keyword.
    bool hasTemplateKeyword() const { return getTemplateKeywordLoc().isValid(); }
  
    /// Determines whether the member name was followed by an
    /// explicit template argument list.
    bool hasExplicitTemplateArgs() const { return getLAngleLoc().isValid(); }
  
    /// Copies the template arguments (if present) into the given
    /// structure.
    void copyTemplateArgumentsInto(TemplateArgumentListInfo &List) const {
      if (hasExplicitTemplateArgs())
        getTrailingObjects<ASTTemplateKWAndArgsInfo>()->copyInto(
            getTrailingObjects<TemplateArgumentLoc>(), List);
    }
  
    /// Retrieve the template arguments provided as part of this
    /// template-id.
    const TemplateArgumentLoc *getTemplateArgs() const {
      if (!hasExplicitTemplateArgs())
        return nullptr;
  
      return getTrailingObjects<TemplateArgumentLoc>();
    }
  
    /// Retrieve the number of template arguments provided as part of this
    /// template-id.
    unsigned getNumTemplateArgs() const {
      if (!hasExplicitTemplateArgs())
        return 0;
  
      return getTrailingObjects<ASTTemplateKWAndArgsInfo>()->NumTemplateArgs;
    }
  
    ArrayRef<TemplateArgumentLoc> template_arguments() const {
      return {getTemplateArgs(), getNumTemplateArgs()};
    }
  
    /// Retrieve the member declaration name info.
    DeclarationNameInfo getMemberNameInfo() const {
      return DeclarationNameInfo(MemberDecl->getDeclName(),
                                 MemberLoc, MemberDNLoc);
    }
  
    SourceLocation getOperatorLoc() const { return MemberExprBits.OperatorLoc; }
  
    bool isArrow() const { return MemberExprBits.IsArrow; }
    void setArrow(bool A) { MemberExprBits.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 getBeginLoc() const LLVM_READONLY;
    SourceLocation getEndLoc() const LLVM_READONLY;
  
    SourceLocation getExprLoc() const LLVM_READONLY { return MemberLoc; }
  
    /// Determine whether the base of this explicit is implicit.
    bool isImplicitAccess() const {
      return getBase() && getBase()->isImplicitCXXThis();
    }
  
    /// 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 MemberExprBits.HadMultipleCandidates;
    }
    /// 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) {
      MemberExprBits.HadMultipleCandidates = V;
    }
  
    /// Returns true if virtual dispatch is performed.
    /// If the member access is fully qualified, (i.e. X::f()), virtual
    /// dispatching is not performed. In -fapple-kext mode qualified
    /// calls to virtual method will still go through the vtable.
    bool performsVirtualDispatch(const LangOptions &LO) const {
      return LO.AppleKext || !hasQualifier();
    }
  
    /// Is this expression a non-odr-use reference, and if so, why?
    /// This is only meaningful if the named member is a static member.
    NonOdrUseReason isNonOdrUse() const {
      return static_cast<NonOdrUseReason>(MemberExprBits.NonOdrUseReason);
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == MemberExprClass;
    }
  
    // Iterators
    child_range children() { return child_range(&Base, &Base+1); }
    const_child_range children() const {
      return const_child_range(&Base, &Base + 1);
    }
  };
  
  /// 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),
          LParenLoc(lparenloc), TInfoAndScope(tinfo, fileScope), Init(init) {
      setDependence(computeDependence(this));
    }
  
    /// 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 getBeginLoc() const LLVM_READONLY {
      // FIXME: Init should never be null.
      if (!Init)
        return SourceLocation();
      if (LParenLoc.isInvalid())
        return Init->getBeginLoc();
      return LParenLoc;
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      // FIXME: Init should never be null.
      if (!Init)
        return SourceLocation();
      return Init->getEndLoc();
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == CompoundLiteralExprClass;
    }
  
    // Iterators
    child_range children() { return child_range(&Init, &Init+1); }
    const_child_range children() const {
      return const_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 {
    Stmt *Op;
  
    bool CastConsistency() const;
  
    const CXXBaseSpecifier * const *path_buffer() const {
      return const_cast<CastExpr*>(this)->path_buffer();
    }
    CXXBaseSpecifier **path_buffer();
  
    friend class ASTStmtReader;
  
  protected:
    CastExpr(StmtClass SC, QualType ty, ExprValueKind VK, const CastKind kind,
             Expr *op, unsigned BasePathSize, bool HasFPFeatures)
        : Expr(SC, ty, VK, OK_Ordinary), Op(op) {
      CastExprBits.Kind = kind;
      CastExprBits.PartOfExplicitCast = false;
      CastExprBits.BasePathSize = BasePathSize;
      assert((CastExprBits.BasePathSize == BasePathSize) &&
             "BasePathSize overflow!");
      setDependence(computeDependence(this));
      assert(CastConsistency());
      CastExprBits.HasFPFeatures = HasFPFeatures;
    }
  
    /// Construct an empty cast.
    CastExpr(StmtClass SC, EmptyShell Empty, unsigned BasePathSize,
             bool HasFPFeatures)
        : Expr(SC, Empty) {
      CastExprBits.PartOfExplicitCast = false;
      CastExprBits.BasePathSize = BasePathSize;
      CastExprBits.HasFPFeatures = HasFPFeatures;
      assert((CastExprBits.BasePathSize == BasePathSize) &&
             "BasePathSize overflow!");
    }
  
    /// Return a pointer to the trailing FPOptions.
    /// \pre hasStoredFPFeatures() == true
    FPOptionsOverride *getTrailingFPFeatures();
    const FPOptionsOverride *getTrailingFPFeatures() const {
      return const_cast<CastExpr *>(this)->getTrailingFPFeatures();
    }
  
  public:
    CastKind getCastKind() const { return (CastKind) CastExprBits.Kind; }
    void setCastKind(CastKind K) { CastExprBits.Kind = K; }
  
    static const char *getCastKindName(CastKind CK);
    const char *getCastKindName() const { return getCastKindName(getCastKind()); }
  
    Expr *getSubExpr() { return cast<Expr>(Op); }
    const Expr *getSubExpr() const { return cast<Expr>(Op); }
    void setSubExpr(Expr *E) { Op = E; }
  
    /// 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();
    }
  
    /// If this cast applies a user-defined conversion, retrieve the conversion
    /// function that it invokes.
    NamedDecl *getConversionFunction() const;
  
    typedef CXXBaseSpecifier **path_iterator;
    typedef const CXXBaseSpecifier *const *path_const_iterator;
    bool path_empty() const { return path_size() == 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(); }
  
    llvm::iterator_range<path_iterator> path() {
      return llvm::make_range(path_begin(), path_end());
    }
    llvm::iterator_range<path_const_iterator> path() const {
      return llvm::make_range(path_begin(), path_end());
    }
  
    const FieldDecl *getTargetUnionField() const {
      assert(getCastKind() == CK_ToUnion);
      return getTargetFieldForToUnionCast(getType(), getSubExpr()->getType());
    }
  
    bool hasStoredFPFeatures() const { return CastExprBits.HasFPFeatures; }
  
    /// Get FPOptionsOverride from trailing storage.
    FPOptionsOverride getStoredFPFeatures() const {
      assert(hasStoredFPFeatures());
      return *getTrailingFPFeatures();
    }
  
    // Get the FP features status of this operation. Only meaningful for
    // operations on floating point types.
    FPOptions getFPFeaturesInEffect(const LangOptions &LO) const {
      if (hasStoredFPFeatures())
        return getStoredFPFeatures().applyOverrides(LO);
      return FPOptions::defaultWithoutTrailingStorage(LO);
    }
  
    FPOptionsOverride getFPFeatures() const {
      if (hasStoredFPFeatures())
        return getStoredFPFeatures();
      return FPOptionsOverride();
    }
  
    static const FieldDecl *getTargetFieldForToUnionCast(QualType unionType,
                                                         QualType opType);
    static const FieldDecl *getTargetFieldForToUnionCast(const RecordDecl *RD,
                                                         QualType opType);
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() >= firstCastExprConstant &&
             T->getStmtClass() <= lastCastExprConstant;
    }
  
    // Iterators
    child_range children() { return child_range(&Op, &Op+1); }
    const_child_range children() const { return const_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 final
      : public CastExpr,
        private llvm::TrailingObjects<ImplicitCastExpr, CXXBaseSpecifier *,
                                      FPOptionsOverride> {
  
    ImplicitCastExpr(QualType ty, CastKind kind, Expr *op,
                     unsigned BasePathLength, FPOptionsOverride FPO,
                     ExprValueKind VK)
        : CastExpr(ImplicitCastExprClass, ty, VK, kind, op, BasePathLength,
                   FPO.requiresTrailingStorage()) {
      if (hasStoredFPFeatures())
        *getTrailingFPFeatures() = FPO;
    }
  
    /// Construct an empty implicit cast.
    explicit ImplicitCastExpr(EmptyShell Shell, unsigned PathSize,
                              bool HasFPFeatures)
        : CastExpr(ImplicitCastExprClass, Shell, PathSize, HasFPFeatures) {}
  
    unsigned numTrailingObjects(OverloadToken<CXXBaseSpecifier *>) const {
      return path_size();
    }
  
  public:
    enum OnStack_t { OnStack };
    ImplicitCastExpr(OnStack_t _, QualType ty, CastKind kind, Expr *op,
                     ExprValueKind VK, FPOptionsOverride FPO)
        : CastExpr(ImplicitCastExprClass, ty, VK, kind, op, 0,
                   FPO.requiresTrailingStorage()) {
      if (hasStoredFPFeatures())
        *getTrailingFPFeatures() = FPO;
    }
  
    bool isPartOfExplicitCast() const { return CastExprBits.PartOfExplicitCast; }
    void setIsPartOfExplicitCast(bool PartOfExplicitCast) {
      CastExprBits.PartOfExplicitCast = PartOfExplicitCast;
    }
  
    static ImplicitCastExpr *Create(const ASTContext &Context, QualType T,
                                    CastKind Kind, Expr *Operand,
                                    const CXXCastPath *BasePath,
                                    ExprValueKind Cat, FPOptionsOverride FPO);
  
    static ImplicitCastExpr *CreateEmpty(const ASTContext &Context,
                                         unsigned PathSize, bool HasFPFeatures);
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getSubExpr()->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getSubExpr()->getEndLoc();
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ImplicitCastExprClass;
    }
  
    friend TrailingObjects;
    friend class CastExpr;
  };
  
  /// 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,
                     bool HasFPFeatures, TypeSourceInfo *writtenTy)
        : CastExpr(SC, exprTy, VK, kind, op, PathSize, HasFPFeatures),
          TInfo(writtenTy) {}
  
    /// Construct an empty explicit cast.
    ExplicitCastExpr(StmtClass SC, EmptyShell Shell, unsigned PathSize,
                     bool HasFPFeatures)
        : CastExpr(SC, Shell, PathSize, HasFPFeatures) {}
  
  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 final
      : public ExplicitCastExpr,
        private llvm::TrailingObjects<CStyleCastExpr, CXXBaseSpecifier *,
                                      FPOptionsOverride> {
    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, FPOptionsOverride FPO,
                   TypeSourceInfo *writtenTy, SourceLocation l, SourceLocation r)
        : ExplicitCastExpr(CStyleCastExprClass, exprTy, vk, kind, op, PathSize,
                           FPO.requiresTrailingStorage(), writtenTy),
          LPLoc(l), RPLoc(r) {
      if (hasStoredFPFeatures())
        *getTrailingFPFeatures() = FPO;
    }
  
    /// Construct an empty C-style explicit cast.
    explicit CStyleCastExpr(EmptyShell Shell, unsigned PathSize,
                            bool HasFPFeatures)
        : ExplicitCastExpr(CStyleCastExprClass, Shell, PathSize, HasFPFeatures) {}
  
    unsigned numTrailingObjects(OverloadToken<CXXBaseSpecifier *>) const {
      return path_size();
    }
  
  public:
    static CStyleCastExpr *
    Create(const ASTContext &Context, QualType T, ExprValueKind VK, CastKind K,
           Expr *Op, const CXXCastPath *BasePath, FPOptionsOverride FPO,
           TypeSourceInfo *WrittenTy, SourceLocation L, SourceLocation R);
  
    static CStyleCastExpr *CreateEmpty(const ASTContext &Context,
                                       unsigned PathSize, bool HasFPFeatures);
  
    SourceLocation getLParenLoc() const { return LPLoc; }
    void setLParenLoc(SourceLocation L) { LPLoc = L; }
  
    SourceLocation getRParenLoc() const { return RPLoc; }
    void setRParenLoc(SourceLocation L) { RPLoc = L; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return LPLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getSubExpr()->getEndLoc();
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == CStyleCastExprClass;
    }
  
    friend TrailingObjects;
    friend class CastExpr;
  };
  
  /// 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 {
    enum { LHS, RHS, END_EXPR };
    Stmt *SubExprs[END_EXPR];
  
  public:
    typedef BinaryOperatorKind Opcode;
  
  protected:
    size_t offsetOfTrailingStorage() const;
  
    /// Return a pointer to the trailing FPOptions
    FPOptionsOverride *getTrailingFPFeatures() {
      assert(BinaryOperatorBits.HasFPFeatures);
      return reinterpret_cast<FPOptionsOverride *>(
          reinterpret_cast<char *>(this) + offsetOfTrailingStorage());
    }
    const FPOptionsOverride *getTrailingFPFeatures() const {
      assert(BinaryOperatorBits.HasFPFeatures);
      return reinterpret_cast<const FPOptionsOverride *>(
          reinterpret_cast<const char *>(this) + offsetOfTrailingStorage());
    }
  
    /// Build a binary operator, assuming that appropriate storage has been
    /// allocated for the trailing objects when needed.
    BinaryOperator(const ASTContext &Ctx, Expr *lhs, Expr *rhs, Opcode opc,
                   QualType ResTy, ExprValueKind VK, ExprObjectKind OK,
                   SourceLocation opLoc, FPOptionsOverride FPFeatures);
  
    /// Construct an empty binary operator.
    explicit BinaryOperator(EmptyShell Empty) : Expr(BinaryOperatorClass, Empty) {
      BinaryOperatorBits.Opc = BO_Comma;
    }
  
  public:
    static BinaryOperator *CreateEmpty(const ASTContext &C, bool hasFPFeatures);
  
    static BinaryOperator *Create(const ASTContext &C, Expr *lhs, Expr *rhs,
                                  Opcode opc, QualType ResTy, ExprValueKind VK,
                                  ExprObjectKind OK, SourceLocation opLoc,
                                  FPOptionsOverride FPFeatures);
    SourceLocation getExprLoc() const { return getOperatorLoc(); }
    SourceLocation getOperatorLoc() const { return BinaryOperatorBits.OpLoc; }
    void setOperatorLoc(SourceLocation L) { BinaryOperatorBits.OpLoc = L; }
  
    Opcode getOpcode() const {
      return static_cast<Opcode>(BinaryOperatorBits.Opc);
    }
    void setOpcode(Opcode Opc) { BinaryOperatorBits.Opc = Opc; }
  
    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 getBeginLoc() const LLVM_READONLY {
      return getLHS()->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getRHS()->getEndLoc();
    }
  
    /// 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()); }
  
    /// Retrieve the binary opcode that corresponds to the given
    /// overloaded operator.
    static Opcode getOverloadedOpcode(OverloadedOperatorKind OO);
  
    /// Retrieve the overloaded operator kind that corresponds to
    /// the given binary opcode.
    static OverloadedOperatorKind getOverloadedOperator(Opcode Opc);
  
    /// predicates to categorize the respective opcodes.
    static bool isPtrMemOp(Opcode Opc) {
      return Opc == BO_PtrMemD || Opc == BO_PtrMemI;
    }
    bool isPtrMemOp() const { return isPtrMemOp(getOpcode()); }
  
    static bool isMultiplicativeOp(Opcode Opc) {
      return Opc >= BO_Mul && Opc <= BO_Rem;
    }
    bool isMultiplicativeOp() const { return isMultiplicativeOp(getOpcode()); }
    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_Cmp && Opc<=BO_NE; }
    bool isComparisonOp() const { return isComparisonOp(getOpcode()); }
  
    static bool isCommaOp(Opcode Opc) { return Opc == BO_Comma; }
    bool isCommaOp() const { return isCommaOp(getOpcode()); }
  
    static Opcode negateComparisonOp(Opcode Opc) {
      switch (Opc) {
      default:
        llvm_unreachable("Not a comparison 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 comparison 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());
    }
  
    // Return true if a binary operator using the specified opcode and operands
    // would match the 'p = (i8*)nullptr + n' idiom for casting a pointer-sized
    // integer to a pointer.
    static bool isNullPointerArithmeticExtension(ASTContext &Ctx, Opcode Opc,
                                                 Expr *LHS, Expr *RHS);
  
    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);
    }
    const_child_range children() const {
      return const_child_range(&SubExprs[0], &SubExprs[0] + END_EXPR);
    }
  
    /// Set and fetch the bit that shows whether FPFeatures needs to be
    /// allocated in Trailing Storage
    void setHasStoredFPFeatures(bool B) { BinaryOperatorBits.HasFPFeatures = B; }
    bool hasStoredFPFeatures() const { return BinaryOperatorBits.HasFPFeatures; }
  
    /// Get FPFeatures from trailing storage
    FPOptionsOverride getStoredFPFeatures() const {
      assert(hasStoredFPFeatures());
      return *getTrailingFPFeatures();
    }
    /// Set FPFeatures in trailing storage, used only by Serialization
    void setStoredFPFeatures(FPOptionsOverride F) {
      assert(BinaryOperatorBits.HasFPFeatures);
      *getTrailingFPFeatures() = F;
    }
  
    // Get the FP features status of this operator. Only meaningful for
    // operations on floating point types.
    FPOptions getFPFeaturesInEffect(const LangOptions &LO) const {
      if (BinaryOperatorBits.HasFPFeatures)
        return getStoredFPFeatures().applyOverrides(LO);
      return FPOptions::defaultWithoutTrailingStorage(LO);
    }
  
    // This is used in ASTImporter
    FPOptionsOverride getFPFeatures(const LangOptions &LO) const {
      if (BinaryOperatorBits.HasFPFeatures)
        return getStoredFPFeatures();
      return FPOptionsOverride();
    }
  
    // Get the FP contractability status of this operator. Only meaningful for
    // operations on floating point types.
    bool isFPContractableWithinStatement(const LangOptions &LO) const {
      return getFPFeaturesInEffect(LO).allowFPContractWithinStatement();
    }
  
    // Get the FENV_ACCESS status of this operator. Only meaningful for
    // operations on floating point types.
    bool isFEnvAccessOn(const LangOptions &LO) const {
      return getFPFeaturesInEffect(LO).getAllowFEnvAccess();
    }
  
  protected:
    BinaryOperator(const ASTContext &Ctx, Expr *lhs, Expr *rhs, Opcode opc,
                   QualType ResTy, ExprValueKind VK, ExprObjectKind OK,
                   SourceLocation opLoc, FPOptionsOverride FPFeatures,
                   bool dead2);
  
    /// Construct an empty BinaryOperator, SC is CompoundAssignOperator.
    BinaryOperator(StmtClass SC, EmptyShell Empty) : Expr(SC, Empty) {
      BinaryOperatorBits.Opc = BO_MulAssign;
    }
  
    /// Return the size in bytes needed for the trailing objects.
    /// Used to allocate the right amount of storage.
    static unsigned sizeOfTrailingObjects(bool HasFPFeatures) {
      return HasFPFeatures * sizeof(FPOptionsOverride);
    }
  };
  
  /// 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;
  
    /// Construct an empty CompoundAssignOperator.
    explicit CompoundAssignOperator(const ASTContext &C, EmptyShell Empty,
                                    bool hasFPFeatures)
        : BinaryOperator(CompoundAssignOperatorClass, Empty) {}
  
  protected:
    CompoundAssignOperator(const ASTContext &C, Expr *lhs, Expr *rhs, Opcode opc,
                           QualType ResType, ExprValueKind VK, ExprObjectKind OK,
                           SourceLocation OpLoc, FPOptionsOverride FPFeatures,
                           QualType CompLHSType, QualType CompResultType)
        : BinaryOperator(C, lhs, rhs, opc, ResType, VK, OK, OpLoc, FPFeatures,
                         true),
          ComputationLHSType(CompLHSType), ComputationResultType(CompResultType) {
      assert(isCompoundAssignmentOp() &&
             "Only should be used for compound assignments");
    }
  
  public:
    static CompoundAssignOperator *CreateEmpty(const ASTContext &C,
                                               bool hasFPFeatures);
  
    static CompoundAssignOperator *
    Create(const ASTContext &C, Expr *lhs, Expr *rhs, Opcode opc, QualType ResTy,
           ExprValueKind VK, ExprObjectKind OK, SourceLocation opLoc,
           FPOptionsOverride FPFeatures, QualType CompLHSType = QualType(),
           QualType CompResultType = QualType());
  
    // The two computation types are the type the LHS is converted
    // to for the computation and the type of the result; the two are
    // distinct in a few cases (specifically, int+=ptr and ptr-=ptr).
    QualType getComputationLHSType() const { return ComputationLHSType; }
    void setComputationLHSType(QualType T) { ComputationLHSType = T; }
  
    QualType getComputationResultType() const { return ComputationResultType; }
    void setComputationResultType(QualType T) { ComputationResultType = T; }
  
    static bool classof(const Stmt *S) {
      return S->getStmtClass() == CompoundAssignOperatorClass;
    }
  };
  
  inline size_t BinaryOperator::offsetOfTrailingStorage() const {
    assert(BinaryOperatorBits.HasFPFeatures);
    return isa<CompoundAssignOperator>(this) ? sizeof(CompoundAssignOperator)
                                             : sizeof(BinaryOperator);
  }
  
  /// AbstractConditionalOperator - An abstract base class for
  /// ConditionalOperator and BinaryConditionalOperator.
  class AbstractConditionalOperator : public Expr {
    SourceLocation QuestionLoc, ColonLoc;
    friend class ASTStmtReader;
  
  protected:
    AbstractConditionalOperator(StmtClass SC, QualType T, ExprValueKind VK,
                                ExprObjectKind OK, SourceLocation qloc,
                                SourceLocation cloc)
        : Expr(SC, T, VK, OK), QuestionLoc(qloc), ColonLoc(cloc) {}
  
    AbstractConditionalOperator(StmtClass SC, EmptyShell Empty)
      : Expr(SC, Empty) { }
  
  public:
    // getCond - Return the expression representing the condition for
    //   the ?: operator.
    Expr *getCond() const;
  
    // getTrueExpr - Return the subexpression representing the value of
    //   the expression if the condition evaluates to true.
    Expr *getTrueExpr() const;
  
    // getFalseExpr - Return the subexpression representing the value of
    //   the expression if the condition evaluates to false.  This is
    //   the same as getRHS.
    Expr *getFalseExpr() const;
  
    SourceLocation getQuestionLoc() const { return QuestionLoc; }
    SourceLocation getColonLoc() const { return ColonLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ConditionalOperatorClass ||
             T->getStmtClass() == BinaryConditionalOperatorClass;
    }
  };
  
  /// ConditionalOperator - The ?: ternary operator.  The GNU "missing
  /// middle" extension is a BinaryConditionalOperator.
  class ConditionalOperator : public AbstractConditionalOperator {
    enum { COND, LHS, RHS, END_EXPR };
    Stmt* SubExprs[END_EXPR]; // Left/Middle/Right hand sides.
  
    friend class ASTStmtReader;
  public:
    ConditionalOperator(Expr *cond, SourceLocation QLoc, Expr *lhs,
                        SourceLocation CLoc, Expr *rhs, QualType t,
                        ExprValueKind VK, ExprObjectKind OK)
        : AbstractConditionalOperator(ConditionalOperatorClass, t, VK, OK, QLoc,
                                      CLoc) {
      SubExprs[COND] = cond;
      SubExprs[LHS] = lhs;
      SubExprs[RHS] = rhs;
      setDependence(computeDependence(this));
    }
  
    /// Build an empty conditional operator.
    explicit ConditionalOperator(EmptyShell Empty)
      : AbstractConditionalOperator(ConditionalOperatorClass, Empty) { }
  
    // getCond - Return the expression representing the condition for
    //   the ?: operator.
    Expr *getCond() const { return cast<Expr>(SubExprs[COND]); }
  
    // getTrueExpr - Return the subexpression representing the value of
    //   the expression if the condition evaluates to true.
    Expr *getTrueExpr() const { return cast<Expr>(SubExprs[LHS]); }
  
    // getFalseExpr - Return the subexpression representing the value of
    //   the expression if the condition evaluates to false.  This is
    //   the same as getRHS.
    Expr *getFalseExpr() const { return cast<Expr>(SubExprs[RHS]); }
  
    Expr *getLHS() const { return cast<Expr>(SubExprs[LHS]); }
    Expr *getRHS() const { return cast<Expr>(SubExprs[RHS]); }
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getCond()->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getRHS()->getEndLoc();
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ConditionalOperatorClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(&SubExprs[0], &SubExprs[0]+END_EXPR);
    }
    const_child_range children() const {
      return const_child_range(&SubExprs[0], &SubExprs[0] + END_EXPR);
    }
  };
  
  /// BinaryConditionalOperator - The GNU extension to the conditional
  /// operator which allows the middle operand to be omitted.
  ///
  /// This is a different expression kind on the assumption that almost
  /// every client ends up needing to know that these are different.
  class BinaryConditionalOperator : public AbstractConditionalOperator {
    enum { COMMON, COND, LHS, RHS, NUM_SUBEXPRS };
  
    /// - the common condition/left-hand-side expression, which will be
    ///   evaluated as the opaque value
    /// - the condition, expressed in terms of the opaque value
    /// - the left-hand-side, expressed in terms of the opaque value
    /// - the right-hand-side
    Stmt *SubExprs[NUM_SUBEXPRS];
    OpaqueValueExpr *OpaqueValue;
  
    friend class ASTStmtReader;
  public:
    BinaryConditionalOperator(Expr *common, OpaqueValueExpr *opaqueValue,
                              Expr *cond, Expr *lhs, Expr *rhs,
                              SourceLocation qloc, SourceLocation cloc,
                              QualType t, ExprValueKind VK, ExprObjectKind OK)
        : AbstractConditionalOperator(BinaryConditionalOperatorClass, t, VK, OK,
                                      qloc, cloc),
          OpaqueValue(opaqueValue) {
      SubExprs[COMMON] = common;
      SubExprs[COND] = cond;
      SubExprs[LHS] = lhs;
      SubExprs[RHS] = rhs;
      assert(OpaqueValue->getSourceExpr() == common && "Wrong opaque value");
      setDependence(computeDependence(this));
    }
  
    /// Build an empty conditional operator.
    explicit BinaryConditionalOperator(EmptyShell Empty)
      : AbstractConditionalOperator(BinaryConditionalOperatorClass, Empty) { }
  
    /// getCommon - Return the common expression, written to the
    ///   left of the condition.  The opaque value will be bound to the
    ///   result of this expression.
    Expr *getCommon() const { return cast<Expr>(SubExprs[COMMON]); }
  
    /// getOpaqueValue - Return the opaque value placeholder.
    OpaqueValueExpr *getOpaqueValue() const { return OpaqueValue; }
  
    /// getCond - Return the condition expression; this is defined
    ///   in terms of the opaque value.
    Expr *getCond() const { return cast<Expr>(SubExprs[COND]); }
  
    /// getTrueExpr - Return the subexpression which will be
    ///   evaluated if the condition evaluates to true;  this is defined
    ///   in terms of the opaque value.
    Expr *getTrueExpr() const {
      return cast<Expr>(SubExprs[LHS]);
    }
  
    /// getFalseExpr - Return the subexpression which will be
    ///   evaluated if the condnition evaluates to false; this is
    ///   defined in terms of the opaque value.
    Expr *getFalseExpr() const {
      return cast<Expr>(SubExprs[RHS]);
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getCommon()->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getFalseExpr()->getEndLoc();
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == BinaryConditionalOperatorClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(SubExprs, SubExprs + NUM_SUBEXPRS);
    }
    const_child_range children() const {
      return const_child_range(SubExprs, SubExprs + NUM_SUBEXPRS);
    }
  };
  
  inline Expr *AbstractConditionalOperator::getCond() const {
    if (const ConditionalOperator *co = dyn_cast<ConditionalOperator>(this))
      return co->getCond();
    return cast<BinaryConditionalOperator>(this)->getCond();
  }
  
  inline Expr *AbstractConditionalOperator::getTrueExpr() const {
    if (const ConditionalOperator *co = dyn_cast<ConditionalOperator>(this))
      return co->getTrueExpr();
    return cast<BinaryConditionalOperator>(this)->getTrueExpr();
  }
  
  inline Expr *AbstractConditionalOperator::getFalseExpr() const {
    if (const ConditionalOperator *co = dyn_cast<ConditionalOperator>(this))
      return co->getFalseExpr();
    return cast<BinaryConditionalOperator>(this)->getFalseExpr();
  }
  
  /// AddrLabelExpr - The GNU address of label extension, representing &&label.
  class AddrLabelExpr : public Expr {
    SourceLocation AmpAmpLoc, LabelLoc;
    LabelDecl *Label;
  public:
    AddrLabelExpr(SourceLocation AALoc, SourceLocation LLoc, LabelDecl *L,
                  QualType t)
        : Expr(AddrLabelExprClass, t, VK_PRValue, OK_Ordinary), AmpAmpLoc(AALoc),
          LabelLoc(LLoc), Label(L) {
      setDependence(ExprDependence::None);
    }
  
    /// Build an empty address of a label expression.
    explicit AddrLabelExpr(EmptyShell Empty)
      : Expr(AddrLabelExprClass, Empty) { }
  
    SourceLocation getAmpAmpLoc() const { return AmpAmpLoc; }
    void setAmpAmpLoc(SourceLocation L) { AmpAmpLoc = L; }
    SourceLocation getLabelLoc() const { return LabelLoc; }
    void setLabelLoc(SourceLocation L) { LabelLoc = L; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return AmpAmpLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return LabelLoc; }
  
    LabelDecl *getLabel() const { return Label; }
    void setLabel(LabelDecl *L) { Label = L; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == AddrLabelExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  /// StmtExpr - This is the GNU Statement Expression extension: ({int X=4; X;}).
  /// The StmtExpr contains a single CompoundStmt node, which it evaluates and
  /// takes the value of the last subexpression.
  ///
  /// A StmtExpr is always an r-value; values "returned" out of a
  /// StmtExpr will be copied.
  class StmtExpr : public Expr {
    Stmt *SubStmt;
    SourceLocation LParenLoc, RParenLoc;
  public:
    StmtExpr(CompoundStmt *SubStmt, QualType T, SourceLocation LParenLoc,
             SourceLocation RParenLoc, unsigned TemplateDepth)
        : Expr(StmtExprClass, T, VK_PRValue, OK_Ordinary), SubStmt(SubStmt),
          LParenLoc(LParenLoc), RParenLoc(RParenLoc) {
      setDependence(computeDependence(this, TemplateDepth));
      // FIXME: A templated statement expression should have an associated
      // DeclContext so that nested declarations always have a dependent context.
      StmtExprBits.TemplateDepth = TemplateDepth;
    }
  
    /// Build an empty statement expression.
    explicit StmtExpr(EmptyShell Empty) : Expr(StmtExprClass, Empty) { }
  
    CompoundStmt *getSubStmt() { return cast<CompoundStmt>(SubStmt); }
    const CompoundStmt *getSubStmt() const { return cast<CompoundStmt>(SubStmt); }
    void setSubStmt(CompoundStmt *S) { SubStmt = S; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return LParenLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    SourceLocation getLParenLoc() const { return LParenLoc; }
    void setLParenLoc(SourceLocation L) { LParenLoc = L; }
    SourceLocation getRParenLoc() const { return RParenLoc; }
    void setRParenLoc(SourceLocation L) { RParenLoc = L; }
  
    unsigned getTemplateDepth() const { return StmtExprBits.TemplateDepth; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == StmtExprClass;
    }
  
    // Iterators
    child_range children() { return child_range(&SubStmt, &SubStmt+1); }
    const_child_range children() const {
      return const_child_range(&SubStmt, &SubStmt + 1);
    }
  };
  
  /// ShuffleVectorExpr - clang-specific builtin-in function
  /// __builtin_shufflevector.
  /// This AST node represents a operator that does a constant
  /// shuffle, similar to LLVM's shufflevector instruction. It takes
  /// two vectors and a variable number of constant indices,
  /// and returns the appropriately shuffled vector.
  class ShuffleVectorExpr : public Expr {
    SourceLocation BuiltinLoc, RParenLoc;
  
    // SubExprs - the list of values passed to the __builtin_shufflevector
    // function. The first two are vectors, and the rest are constant
    // indices.  The number of values in this list is always
    // 2+the number of indices in the vector type.
    Stmt **SubExprs;
    unsigned NumExprs;
  
  public:
    ShuffleVectorExpr(const ASTContext &C, ArrayRef<Expr*> args, QualType Type,
                      SourceLocation BLoc, SourceLocation RP);
  
    /// Build an empty vector-shuffle expression.
    explicit ShuffleVectorExpr(EmptyShell Empty)
      : Expr(ShuffleVectorExprClass, Empty), SubExprs(nullptr) { }
  
    SourceLocation getBuiltinLoc() const { return BuiltinLoc; }
    void setBuiltinLoc(SourceLocation L) { BuiltinLoc = L; }
  
    SourceLocation getRParenLoc() const { return RParenLoc; }
    void setRParenLoc(SourceLocation L) { RParenLoc = L; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return BuiltinLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ShuffleVectorExprClass;
    }
  
    /// getNumSubExprs - Return the size of the SubExprs array.  This includes the
    /// constant expression, the actual arguments passed in, and the function
    /// pointers.
    unsigned getNumSubExprs() const { return NumExprs; }
  
    /// Retrieve the array of expressions.
    Expr **getSubExprs() { return reinterpret_cast<Expr **>(SubExprs); }
  
    /// getExpr - Return the Expr at the specified index.
    Expr *getExpr(unsigned Index) {
      assert((Index < NumExprs) && "Arg access out of range!");
      return cast<Expr>(SubExprs[Index]);
    }
    const Expr *getExpr(unsigned Index) const {
      assert((Index < NumExprs) && "Arg access out of range!");
      return cast<Expr>(SubExprs[Index]);
    }
  
    void setExprs(const ASTContext &C, ArrayRef<Expr *> Exprs);
  
    llvm::APSInt getShuffleMaskIdx(const ASTContext &Ctx, unsigned N) const {
      assert((N < NumExprs - 2) && "Shuffle idx out of range!");
      return getExpr(N+2)->EvaluateKnownConstInt(Ctx);
    }
  
    // Iterators
    child_range children() {
      return child_range(&SubExprs[0], &SubExprs[0]+NumExprs);
    }
    const_child_range children() const {
      return const_child_range(&SubExprs[0], &SubExprs[0] + NumExprs);
    }
  };
  
  /// ConvertVectorExpr - Clang builtin function __builtin_convertvector
  /// This AST node provides support for converting a vector type to another
  /// vector type of the same arity.
  class ConvertVectorExpr : public Expr {
  private:
    Stmt *SrcExpr;
    TypeSourceInfo *TInfo;
    SourceLocation BuiltinLoc, RParenLoc;
  
    friend class ASTReader;
    friend class ASTStmtReader;
    explicit ConvertVectorExpr(EmptyShell Empty) : Expr(ConvertVectorExprClass, Empty) {}
  
  public:
    ConvertVectorExpr(Expr *SrcExpr, TypeSourceInfo *TI, QualType DstType,
                      ExprValueKind VK, ExprObjectKind OK,
                      SourceLocation BuiltinLoc, SourceLocation RParenLoc)
        : Expr(ConvertVectorExprClass, DstType, VK, OK), SrcExpr(SrcExpr),
          TInfo(TI), BuiltinLoc(BuiltinLoc), RParenLoc(RParenLoc) {
      setDependence(computeDependence(this));
    }
  
    /// getSrcExpr - Return the Expr to be converted.
    Expr *getSrcExpr() const { return cast<Expr>(SrcExpr); }
  
    /// getTypeSourceInfo - Return the destination type.
    TypeSourceInfo *getTypeSourceInfo() const {
      return TInfo;
    }
    void setTypeSourceInfo(TypeSourceInfo *ti) {
      TInfo = ti;
    }
  
    /// getBuiltinLoc - Return the location of the __builtin_convertvector token.
    SourceLocation getBuiltinLoc() const { return BuiltinLoc; }
  
    /// getRParenLoc - Return the location of final right parenthesis.
    SourceLocation getRParenLoc() const { return RParenLoc; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return BuiltinLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ConvertVectorExprClass;
    }
  
    // Iterators
    child_range children() { return child_range(&SrcExpr, &SrcExpr+1); }
    const_child_range children() const {
      return const_child_range(&SrcExpr, &SrcExpr + 1);
    }
  };
  
  /// ChooseExpr - GNU builtin-in function __builtin_choose_expr.
  /// This AST node is similar to the conditional operator (?:) in C, with
  /// the following exceptions:
  /// - the test expression must be a integer constant expression.
  /// - the expression returned acts like the chosen subexpression in every
  ///   visible way: the type is the same as that of the chosen subexpression,
  ///   and all predicates (whether it's an l-value, whether it's an integer
  ///   constant expression, etc.) return the same result as for the chosen
  ///   sub-expression.
  class ChooseExpr : public Expr {
    enum { COND, LHS, RHS, END_EXPR };
    Stmt* SubExprs[END_EXPR]; // Left/Middle/Right hand sides.
    SourceLocation BuiltinLoc, RParenLoc;
    bool CondIsTrue;
  public:
    ChooseExpr(SourceLocation BLoc, Expr *cond, Expr *lhs, Expr *rhs, QualType t,
               ExprValueKind VK, ExprObjectKind OK, SourceLocation RP,
               bool condIsTrue)
        : Expr(ChooseExprClass, t, VK, OK), BuiltinLoc(BLoc), RParenLoc(RP),
          CondIsTrue(condIsTrue) {
      SubExprs[COND] = cond;
      SubExprs[LHS] = lhs;
      SubExprs[RHS] = rhs;
  
      setDependence(computeDependence(this));
    }
  
    /// Build an empty __builtin_choose_expr.
    explicit ChooseExpr(EmptyShell Empty) : Expr(ChooseExprClass, Empty) { }
  
    /// isConditionTrue - Return whether the condition is true (i.e. not
    /// equal to zero).
    bool isConditionTrue() const {
      assert(!isConditionDependent() &&
             "Dependent condition isn't true or false");
      return CondIsTrue;
    }
    void setIsConditionTrue(bool isTrue) { CondIsTrue = isTrue; }
  
    bool isConditionDependent() const {
      return getCond()->isTypeDependent() || getCond()->isValueDependent();
    }
  
    /// getChosenSubExpr - Return the subexpression chosen according to the
    /// condition.
    Expr *getChosenSubExpr() const {
      return isConditionTrue() ? getLHS() : getRHS();
    }
  
    Expr *getCond() const { return cast<Expr>(SubExprs[COND]); }
    void setCond(Expr *E) { SubExprs[COND] = E; }
    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 getBuiltinLoc() const { return BuiltinLoc; }
    void setBuiltinLoc(SourceLocation L) { BuiltinLoc = L; }
  
    SourceLocation getRParenLoc() const { return RParenLoc; }
    void setRParenLoc(SourceLocation L) { RParenLoc = L; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return BuiltinLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ChooseExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(&SubExprs[0], &SubExprs[0]+END_EXPR);
    }
    const_child_range children() const {
      return const_child_range(&SubExprs[0], &SubExprs[0] + END_EXPR);
    }
  };
  
  /// GNUNullExpr - Implements the GNU __null extension, which is a name
  /// for a null pointer constant that has integral type (e.g., int or
  /// long) and is the same size and alignment as a pointer. The __null
  /// extension is typically only used by system headers, which define
  /// NULL as __null in C++ rather than using 0 (which is an integer
  /// that may not match the size of a pointer).
  class GNUNullExpr : public Expr {
    /// TokenLoc - The location of the __null keyword.
    SourceLocation TokenLoc;
  
  public:
    GNUNullExpr(QualType Ty, SourceLocation Loc)
        : Expr(GNUNullExprClass, Ty, VK_PRValue, OK_Ordinary), TokenLoc(Loc) {
      setDependence(ExprDependence::None);
    }
  
    /// Build an empty GNU __null expression.
    explicit GNUNullExpr(EmptyShell Empty) : Expr(GNUNullExprClass, Empty) { }
  
    /// getTokenLocation - The location of the __null token.
    SourceLocation getTokenLocation() const { return TokenLoc; }
    void setTokenLocation(SourceLocation L) { TokenLoc = L; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return TokenLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return TokenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == GNUNullExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  /// Represents a call to the builtin function \c __builtin_va_arg.
  class VAArgExpr : public Expr {
    Stmt *Val;
    llvm::PointerIntPair<TypeSourceInfo *, 1, bool> TInfo;
    SourceLocation BuiltinLoc, RParenLoc;
  public:
    VAArgExpr(SourceLocation BLoc, Expr *e, TypeSourceInfo *TInfo,
              SourceLocation RPLoc, QualType t, bool IsMS)
        : Expr(VAArgExprClass, t, VK_PRValue, OK_Ordinary), Val(e),
          TInfo(TInfo, IsMS), BuiltinLoc(BLoc), RParenLoc(RPLoc) {
      setDependence(computeDependence(this));
    }
  
    /// Create an empty __builtin_va_arg expression.
    explicit VAArgExpr(EmptyShell Empty)
        : Expr(VAArgExprClass, Empty), Val(nullptr), TInfo(nullptr, false) {}
  
    const Expr *getSubExpr() const { return cast<Expr>(Val); }
    Expr *getSubExpr() { return cast<Expr>(Val); }
    void setSubExpr(Expr *E) { Val = E; }
  
    /// Returns whether this is really a Win64 ABI va_arg expression.
    bool isMicrosoftABI() const { return TInfo.getInt(); }
    void setIsMicrosoftABI(bool IsMS) { TInfo.setInt(IsMS); }
  
    TypeSourceInfo *getWrittenTypeInfo() const { return TInfo.getPointer(); }
    void setWrittenTypeInfo(TypeSourceInfo *TI) { TInfo.setPointer(TI); }
  
    SourceLocation getBuiltinLoc() const { return BuiltinLoc; }
    void setBuiltinLoc(SourceLocation L) { BuiltinLoc = L; }
  
    SourceLocation getRParenLoc() const { return RParenLoc; }
    void setRParenLoc(SourceLocation L) { RParenLoc = L; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return BuiltinLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == VAArgExprClass;
    }
  
    // Iterators
    child_range children() { return child_range(&Val, &Val+1); }
    const_child_range children() const {
      return const_child_range(&Val, &Val + 1);
    }
  };
  
  /// Represents a function call to one of __builtin_LINE(), __builtin_COLUMN(),
  /// __builtin_FUNCTION(), or __builtin_FILE().
  class SourceLocExpr final : public Expr {
    SourceLocation BuiltinLoc, RParenLoc;
    DeclContext *ParentContext;
  
  public:
    enum IdentKind { Function, File, Line, Column };
  
    SourceLocExpr(const ASTContext &Ctx, IdentKind Type, SourceLocation BLoc,
                  SourceLocation RParenLoc, DeclContext *Context);
  
    /// Build an empty call expression.
    explicit SourceLocExpr(EmptyShell Empty) : Expr(SourceLocExprClass, Empty) {}
  
    /// Return the result of evaluating this SourceLocExpr in the specified
    /// (and possibly null) default argument or initialization context.
    APValue EvaluateInContext(const ASTContext &Ctx,
                              const Expr *DefaultExpr) const;
  
    /// Return a string representing the name of the specific builtin function.
    StringRef getBuiltinStr() const;
  
    IdentKind getIdentKind() const {
      return static_cast<IdentKind>(SourceLocExprBits.Kind);
    }
  
    bool isStringType() const {
      switch (getIdentKind()) {
      case File:
      case Function:
        return true;
      case Line:
      case Column:
        return false;
      }
      llvm_unreachable("unknown source location expression kind");
    }
    bool isIntType() const LLVM_READONLY { return !isStringType(); }
  
    /// If the SourceLocExpr has been resolved return the subexpression
    /// representing the resolved value. Otherwise return null.
    const DeclContext *getParentContext() const { return ParentContext; }
    DeclContext *getParentContext() { return ParentContext; }
  
    SourceLocation getLocation() const { return BuiltinLoc; }
    SourceLocation getBeginLoc() const { return BuiltinLoc; }
    SourceLocation getEndLoc() const { return RParenLoc; }
  
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
  
    const_child_range children() const {
      return const_child_range(child_iterator(), child_iterator());
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == SourceLocExprClass;
    }
  
  private:
    friend class ASTStmtReader;
  };
  
  /// Describes an C or C++ initializer list.
  ///
  /// InitListExpr describes an initializer list, which can be used to
  /// initialize objects of different types, including
  /// struct/class/union types, arrays, and vectors. For example:
  ///
  /// @code
  /// struct foo x = { 1, { 2, 3 } };
  /// @endcode
  ///
  /// Prior to semantic analysis, an initializer list will represent the
  /// initializer list as written by the user, but will have the
  /// placeholder type "void". This initializer list is called the
  /// syntactic form of the initializer, and may contain C99 designated
  /// initializers (represented as DesignatedInitExprs), initializations
  /// of subobject members without explicit braces, and so on. Clients
  /// interested in the original syntax of the initializer list should
  /// use the syntactic form of the initializer list.
  ///
  /// After semantic analysis, the initializer list will represent the
  /// semantic form of the initializer, where the initializations of all
  /// subobjects are made explicit with nested InitListExpr nodes and
  /// C99 designators have been eliminated by placing the designated
  /// initializations into the subobject they initialize. Additionally,
  /// any "holes" in the initialization, where no initializer has been
  /// specified for a particular subobject, will be replaced with
  /// implicitly-generated ImplicitValueInitExpr expressions that
  /// value-initialize the subobjects. Note, however, that the
  /// initializer lists may still have fewer initializers than there are
  /// elements to initialize within the object.
  ///
  /// After semantic analysis has completed, given an initializer list,
  /// method isSemanticForm() returns true if and only if this is the
  /// semantic form of the initializer list (note: the same AST node
  /// may at the same time be the syntactic form).
  /// Given the semantic form of the initializer list, one can retrieve
  /// the syntactic form of that initializer list (when different)
  /// using method getSyntacticForm(); the method returns null if applied
  /// to a initializer list which is already in syntactic form.
  /// Similarly, given the syntactic form (i.e., an initializer list such
  /// that isSemanticForm() returns false), one can retrieve the semantic
  /// form using method getSemanticForm().
  /// Since many initializer lists have the same syntactic and semantic forms,
  /// getSyntacticForm() may return NULL, indicating that the current
  /// semantic initializer list also serves as its syntactic form.
  class InitListExpr : public Expr {
    // FIXME: Eliminate this vector in favor of ASTContext allocation
    typedef ASTVector<Stmt *> InitExprsTy;
    InitExprsTy InitExprs;
    SourceLocation LBraceLoc, RBraceLoc;
  
    /// The alternative form of the initializer list (if it exists).
    /// The int part of the pair stores whether this initializer list is
    /// in semantic form. If not null, the pointer points to:
    ///   - the syntactic form, if this is in semantic form;
    ///   - the semantic form, if this is in syntactic form.
    llvm::PointerIntPair<InitListExpr *, 1, bool> AltForm;
  
    /// Either:
    ///  If this initializer list initializes an array with more elements than
    ///  there are initializers in the list, specifies an expression to be used
    ///  for value initialization of the rest of the elements.
    /// Or
    ///  If this initializer list initializes a union, specifies which
    ///  field within the union will be initialized.
    llvm::PointerUnion<Expr *, FieldDecl *> ArrayFillerOrUnionFieldInit;
  
  public:
    InitListExpr(const ASTContext &C, SourceLocation lbraceloc,
                 ArrayRef<Expr*> initExprs, SourceLocation rbraceloc);
  
    /// Build an empty initializer list.
    explicit InitListExpr(EmptyShell Empty)
      : Expr(InitListExprClass, Empty), AltForm(nullptr, true) { }
  
    unsigned getNumInits() const { return InitExprs.size(); }
  
    /// Retrieve the set of initializers.
    Expr **getInits() { return reinterpret_cast<Expr **>(InitExprs.data()); }
  
    /// Retrieve the set of initializers.
    Expr * const *getInits() const {
      return reinterpret_cast<Expr * const *>(InitExprs.data());
    }
  
    ArrayRef<Expr *> inits() {
      return llvm::makeArrayRef(getInits(), getNumInits());
    }
  
    ArrayRef<Expr *> inits() const {
      return llvm::makeArrayRef(getInits(), getNumInits());
    }
  
    const Expr *getInit(unsigned Init) const {
      assert(Init < getNumInits() && "Initializer access out of range!");
      return cast_or_null<Expr>(InitExprs[Init]);
    }
  
    Expr *getInit(unsigned Init) {
      assert(Init < getNumInits() && "Initializer access out of range!");
      return cast_or_null<Expr>(InitExprs[Init]);
    }
  
    void setInit(unsigned Init, Expr *expr) {
      assert(Init < getNumInits() && "Initializer access out of range!");
      InitExprs[Init] = expr;
  
      if (expr)
        setDependence(getDependence() | expr->getDependence());
    }
  
    /// Mark the semantic form of the InitListExpr as error when the semantic
    /// analysis fails.
    void markError() {
      assert(isSemanticForm());
      setDependence(getDependence() | ExprDependence::ErrorDependent);
    }
  
    /// Reserve space for some number of initializers.
    void reserveInits(const ASTContext &C, unsigned NumInits);
  
    /// Specify the number of initializers
    ///
    /// If there are more than @p NumInits initializers, the remaining
    /// initializers will be destroyed. If there are fewer than @p
    /// NumInits initializers, NULL expressions will be added for the
    /// unknown initializers.
    void resizeInits(const ASTContext &Context, unsigned NumInits);
  
    /// Updates the initializer at index @p Init with the new
    /// expression @p expr, and returns the old expression at that
    /// location.
    ///
    /// When @p Init is out of range for this initializer list, the
    /// initializer list will be extended with NULL expressions to
    /// accommodate the new entry.
    Expr *updateInit(const ASTContext &C, unsigned Init, Expr *expr);
  
    /// If this initializer list initializes an array with more elements
    /// than there are initializers in the list, specifies an expression to be
    /// used for value initialization of the rest of the elements.
    Expr *getArrayFiller() {
      return ArrayFillerOrUnionFieldInit.dyn_cast<Expr *>();
    }
    const Expr *getArrayFiller() const {
      return const_cast<InitListExpr *>(this)->getArrayFiller();
    }
    void setArrayFiller(Expr *filler);
  
    /// Return true if this is an array initializer and its array "filler"
    /// has been set.
    bool hasArrayFiller() const { return getArrayFiller(); }
  
    /// If this initializes a union, specifies which field in the
    /// union to initialize.
    ///
    /// Typically, this field is the first named field within the
    /// union. However, a designated initializer can specify the
    /// initialization of a different field within the union.
    FieldDecl *getInitializedFieldInUnion() {
      return ArrayFillerOrUnionFieldInit.dyn_cast<FieldDecl *>();
    }
    const FieldDecl *getInitializedFieldInUnion() const {
      return const_cast<InitListExpr *>(this)->getInitializedFieldInUnion();
    }
    void setInitializedFieldInUnion(FieldDecl *FD) {
      assert((FD == nullptr
              || getInitializedFieldInUnion() == nullptr
              || getInitializedFieldInUnion() == FD)
             && "Only one field of a union may be initialized at a time!");
      ArrayFillerOrUnionFieldInit = FD;
    }
  
    // Explicit InitListExpr's originate from source code (and have valid source
    // locations). Implicit InitListExpr's are created by the semantic analyzer.
    // FIXME: This is wrong; InitListExprs created by semantic analysis have
    // valid source locations too!
    bool isExplicit() const {
      return LBraceLoc.isValid() && RBraceLoc.isValid();
    }
  
    // Is this an initializer for an array of characters, initialized by a string
    // literal or an @encode?
    bool isStringLiteralInit() const;
  
    /// Is this a transparent initializer list (that is, an InitListExpr that is
    /// purely syntactic, and whose semantics are that of the sole contained
    /// initializer)?
    bool isTransparent() const;
  
    /// Is this the zero initializer {0} in a language which considers it
    /// idiomatic?
    bool isIdiomaticZeroInitializer(const LangOptions &LangOpts) const;
  
    SourceLocation getLBraceLoc() const { return LBraceLoc; }
    void setLBraceLoc(SourceLocation Loc) { LBraceLoc = Loc; }
    SourceLocation getRBraceLoc() const { return RBraceLoc; }
    void setRBraceLoc(SourceLocation Loc) { RBraceLoc = Loc; }
  
    bool isSemanticForm() const { return AltForm.getInt(); }
    InitListExpr *getSemanticForm() const {
      return isSemanticForm() ? nullptr : AltForm.getPointer();
    }
    bool isSyntacticForm() const {
      return !AltForm.getInt() || !AltForm.getPointer();
    }
    InitListExpr *getSyntacticForm() const {
      return isSemanticForm() ? AltForm.getPointer() : nullptr;
    }
  
    void setSyntacticForm(InitListExpr *Init) {
      AltForm.setPointer(Init);
      AltForm.setInt(true);
      Init->AltForm.setPointer(this);
      Init->AltForm.setInt(false);
    }
  
    bool hadArrayRangeDesignator() const {
      return InitListExprBits.HadArrayRangeDesignator != 0;
    }
    void sawArrayRangeDesignator(bool ARD = true) {
      InitListExprBits.HadArrayRangeDesignator = ARD;
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY;
    SourceLocation getEndLoc() const LLVM_READONLY;
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == InitListExprClass;
    }
  
    // Iterators
    child_range children() {
      const_child_range CCR = const_cast<const InitListExpr *>(this)->children();
      return child_range(cast_away_const(CCR.begin()),
                         cast_away_const(CCR.end()));
    }
  
    const_child_range children() const {
      // FIXME: This does not include the array filler expression.
      if (InitExprs.empty())
        return const_child_range(const_child_iterator(), const_child_iterator());
      return const_child_range(&InitExprs[0], &InitExprs[0] + InitExprs.size());
    }
  
    typedef InitExprsTy::iterator iterator;
    typedef InitExprsTy::const_iterator const_iterator;
    typedef InitExprsTy::reverse_iterator reverse_iterator;
    typedef InitExprsTy::const_reverse_iterator const_reverse_iterator;
  
    iterator begin() { return InitExprs.begin(); }
    const_iterator begin() const { return InitExprs.begin(); }
    iterator end() { return InitExprs.end(); }
    const_iterator end() const { return InitExprs.end(); }
    reverse_iterator rbegin() { return InitExprs.rbegin(); }
    const_reverse_iterator rbegin() const { return InitExprs.rbegin(); }
    reverse_iterator rend() { return InitExprs.rend(); }
    const_reverse_iterator rend() const { return InitExprs.rend(); }
  
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
  };
  
  /// Represents a C99 designated initializer expression.
  ///
  /// A designated initializer expression (C99 6.7.8) contains one or
  /// more designators (which can be field designators, array
  /// designators, or GNU array-range designators) followed by an
  /// expression that initializes the field or element(s) that the
  /// designators refer to. For example, given:
  ///
  /// @code
  /// struct point {
  ///   double x;
  ///   double y;
  /// };
  /// struct point ptarray[10] = { [2].y = 1.0, [2].x = 2.0, [0].x = 1.0 };
  /// @endcode
  ///
  /// The InitListExpr contains three DesignatedInitExprs, the first of
  /// which covers @c [2].y=1.0. This DesignatedInitExpr will have two
  /// designators, one array designator for @c [2] followed by one field
  /// designator for @c .y. The initialization expression will be 1.0.
  class DesignatedInitExpr final
      : public Expr,
        private llvm::TrailingObjects<DesignatedInitExpr, Stmt *> {
  public:
    /// Forward declaration of the Designator class.
    class Designator;
  
  private:
    /// The location of the '=' or ':' prior to the actual initializer
    /// expression.
    SourceLocation EqualOrColonLoc;
  
    /// Whether this designated initializer used the GNU deprecated
    /// syntax rather than the C99 '=' syntax.
    unsigned GNUSyntax : 1;
  
    /// The number of designators in this initializer expression.
    unsigned NumDesignators : 15;
  
    /// The number of subexpressions of this initializer expression,
    /// which contains both the initializer and any additional
    /// expressions used by array and array-range designators.
    unsigned NumSubExprs : 16;
  
    /// The designators in this designated initialization
    /// expression.
    Designator *Designators;
  
    DesignatedInitExpr(const ASTContext &C, QualType Ty,
                       llvm::ArrayRef<Designator> Designators,
                       SourceLocation EqualOrColonLoc, bool GNUSyntax,
                       ArrayRef<Expr *> IndexExprs, Expr *Init);
  
    explicit DesignatedInitExpr(unsigned NumSubExprs)
      : Expr(DesignatedInitExprClass, EmptyShell()),
        NumDesignators(0), NumSubExprs(NumSubExprs), Designators(nullptr) { }
  
  public:
    /// A field designator, e.g., ".x".
    struct FieldDesignator {
      /// Refers to the field that is being initialized. The low bit
      /// of this field determines whether this is actually a pointer
      /// to an IdentifierInfo (if 1) or a FieldDecl (if 0). When
      /// initially constructed, a field designator will store an
      /// IdentifierInfo*. After semantic analysis has resolved that
      /// name, the field designator will instead store a FieldDecl*.
      uintptr_t NameOrField;
  
      /// The location of the '.' in the designated initializer.
      SourceLocation DotLoc;
  
      /// The location of the field name in the designated initializer.
      SourceLocation FieldLoc;
    };
  
    /// An array or GNU array-range designator, e.g., "[9]" or "[10..15]".
    struct ArrayOrRangeDesignator {
      /// Location of the first index expression within the designated
      /// initializer expression's list of subexpressions.
      unsigned Index;
      /// The location of the '[' starting the array range designator.
      SourceLocation LBracketLoc;
      /// The location of the ellipsis separating the start and end
      /// indices. Only valid for GNU array-range designators.
      SourceLocation EllipsisLoc;
      /// The location of the ']' terminating the array range designator.
      SourceLocation RBracketLoc;
    };
  
    /// Represents a single C99 designator.
    ///
    /// @todo This class is infuriatingly similar to clang::Designator,
    /// but minor differences (storing indices vs. storing pointers)
    /// keep us from reusing it. Try harder, later, to rectify these
    /// differences.
    class Designator {
      /// The kind of designator this describes.
      enum {
        FieldDesignator,
        ArrayDesignator,
        ArrayRangeDesignator
      } Kind;
  
      union {
        /// A field designator, e.g., ".x".
        struct FieldDesignator Field;
        /// An array or GNU array-range designator, e.g., "[9]" or "[10..15]".
        struct ArrayOrRangeDesignator ArrayOrRange;
      };
      friend class DesignatedInitExpr;
  
    public:
      Designator() {}
  
      /// Initializes a field designator.
      Designator(const IdentifierInfo *FieldName, SourceLocation DotLoc,
                 SourceLocation FieldLoc)
        : Kind(FieldDesignator) {
        new (&Field) DesignatedInitExpr::FieldDesignator;
        Field.NameOrField = reinterpret_cast<uintptr_t>(FieldName) | 0x01;
        Field.DotLoc = DotLoc;
        Field.FieldLoc = FieldLoc;
      }
  
      /// Initializes an array designator.
      Designator(unsigned Index, SourceLocation LBracketLoc,
                 SourceLocation RBracketLoc)
        : Kind(ArrayDesignator) {
        new (&ArrayOrRange) DesignatedInitExpr::ArrayOrRangeDesignator;
        ArrayOrRange.Index = Index;
        ArrayOrRange.LBracketLoc = LBracketLoc;
        ArrayOrRange.EllipsisLoc = SourceLocation();
        ArrayOrRange.RBracketLoc = RBracketLoc;
      }
  
      /// Initializes a GNU array-range designator.
      Designator(unsigned Index, SourceLocation LBracketLoc,
                 SourceLocation EllipsisLoc, SourceLocation RBracketLoc)
        : Kind(ArrayRangeDesignator) {
        new (&ArrayOrRange) DesignatedInitExpr::ArrayOrRangeDesignator;
        ArrayOrRange.Index = Index;
        ArrayOrRange.LBracketLoc = LBracketLoc;
        ArrayOrRange.EllipsisLoc = EllipsisLoc;
        ArrayOrRange.RBracketLoc = RBracketLoc;
      }
  
      bool isFieldDesignator() const { return Kind == FieldDesignator; }
      bool isArrayDesignator() const { return Kind == ArrayDesignator; }
      bool isArrayRangeDesignator() const { return Kind == ArrayRangeDesignator; }
  
      IdentifierInfo *getFieldName() const;
  
      FieldDecl *getField() const {
        assert(Kind == FieldDesignator && "Only valid on a field designator");
        if (Field.NameOrField & 0x01)
          return nullptr;
        else
          return reinterpret_cast<FieldDecl *>(Field.NameOrField);
      }
  
      void setField(FieldDecl *FD) {
        assert(Kind == FieldDesignator && "Only valid on a field designator");
        Field.NameOrField = reinterpret_cast<uintptr_t>(FD);
      }
  
      SourceLocation getDotLoc() const {
        assert(Kind == FieldDesignator && "Only valid on a field designator");
        return Field.DotLoc;
      }
  
      SourceLocation getFieldLoc() const {
        assert(Kind == FieldDesignator && "Only valid on a field designator");
        return Field.FieldLoc;
      }
  
      SourceLocation getLBracketLoc() const {
        assert((Kind == ArrayDesignator || Kind == ArrayRangeDesignator) &&
               "Only valid on an array or array-range designator");
        return ArrayOrRange.LBracketLoc;
      }
  
      SourceLocation getRBracketLoc() const {
        assert((Kind == ArrayDesignator || Kind == ArrayRangeDesignator) &&
               "Only valid on an array or array-range designator");
        return ArrayOrRange.RBracketLoc;
      }
  
      SourceLocation getEllipsisLoc() const {
        assert(Kind == ArrayRangeDesignator &&
               "Only valid on an array-range designator");
        return ArrayOrRange.EllipsisLoc;
      }
  
      unsigned getFirstExprIndex() const {
        assert((Kind == ArrayDesignator || Kind == ArrayRangeDesignator) &&
               "Only valid on an array or array-range designator");
        return ArrayOrRange.Index;
      }
  
      SourceLocation getBeginLoc() const LLVM_READONLY {
        if (Kind == FieldDesignator)
          return getDotLoc().isInvalid()? getFieldLoc() : getDotLoc();
        else
          return getLBracketLoc();
      }
      SourceLocation getEndLoc() const LLVM_READONLY {
        return Kind == FieldDesignator ? getFieldLoc() : getRBracketLoc();
      }
      SourceRange getSourceRange() const LLVM_READONLY {
        return SourceRange(getBeginLoc(), getEndLoc());
      }
    };
  
    static DesignatedInitExpr *Create(const ASTContext &C,
                                      llvm::ArrayRef<Designator> Designators,
                                      ArrayRef<Expr*> IndexExprs,
                                      SourceLocation EqualOrColonLoc,
                                      bool GNUSyntax, Expr *Init);
  
    static DesignatedInitExpr *CreateEmpty(const ASTContext &C,
                                           unsigned NumIndexExprs);
  
    /// Returns the number of designators in this initializer.
    unsigned size() const { return NumDesignators; }
  
    // Iterator access to the designators.
    llvm::MutableArrayRef<Designator> designators() {
      return {Designators, NumDesignators};
    }
  
    llvm::ArrayRef<Designator> designators() const {
      return {Designators, NumDesignators};
    }
  
    Designator *getDesignator(unsigned Idx) { return &designators()[Idx]; }
    const Designator *getDesignator(unsigned Idx) const {
      return &designators()[Idx];
    }
  
    void setDesignators(const ASTContext &C, const Designator *Desigs,
                        unsigned NumDesigs);
  
    Expr *getArrayIndex(const Designator &D) const;
    Expr *getArrayRangeStart(const Designator &D) const;
    Expr *getArrayRangeEnd(const Designator &D) const;
  
    /// Retrieve the location of the '=' that precedes the
    /// initializer value itself, if present.
    SourceLocation getEqualOrColonLoc() const { return EqualOrColonLoc; }
    void setEqualOrColonLoc(SourceLocation L) { EqualOrColonLoc = L; }
  
    /// Whether this designated initializer should result in direct-initialization
    /// of the designated subobject (eg, '{.foo{1, 2, 3}}').
    bool isDirectInit() const { return EqualOrColonLoc.isInvalid(); }
  
    /// Determines whether this designated initializer used the
    /// deprecated GNU syntax for designated initializers.
    bool usesGNUSyntax() const { return GNUSyntax; }
    void setGNUSyntax(bool GNU) { GNUSyntax = GNU; }
  
    /// Retrieve the initializer value.
    Expr *getInit() const {
      return cast<Expr>(*const_cast<DesignatedInitExpr*>(this)->child_begin());
    }
  
    void setInit(Expr *init) {
      *child_begin() = init;
    }
  
    /// Retrieve the total number of subexpressions in this
    /// designated initializer expression, including the actual
    /// initialized value and any expressions that occur within array
    /// and array-range designators.
    unsigned getNumSubExprs() const { return NumSubExprs; }
  
    Expr *getSubExpr(unsigned Idx) const {
      assert(Idx < NumSubExprs && "Subscript out of range");
      return cast<Expr>(getTrailingObjects<Stmt *>()[Idx]);
    }
  
    void setSubExpr(unsigned Idx, Expr *E) {
      assert(Idx < NumSubExprs && "Subscript out of range");
      getTrailingObjects<Stmt *>()[Idx] = E;
    }
  
    /// Replaces the designator at index @p Idx with the series
    /// of designators in [First, Last).
    void ExpandDesignator(const ASTContext &C, unsigned Idx,
                          const Designator *First, const Designator *Last);
  
    SourceRange getDesignatorsSourceRange() const;
  
    SourceLocation getBeginLoc() const LLVM_READONLY;
    SourceLocation getEndLoc() const LLVM_READONLY;
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == DesignatedInitExprClass;
    }
  
    // Iterators
    child_range children() {
      Stmt **begin = getTrailingObjects<Stmt *>();
      return child_range(begin, begin + NumSubExprs);
    }
    const_child_range children() const {
      Stmt * const *begin = getTrailingObjects<Stmt *>();
      return const_child_range(begin, begin + NumSubExprs);
    }
  
    friend TrailingObjects;
  };
  
  /// Represents a place-holder for an object not to be initialized by
  /// anything.
  ///
  /// This only makes sense when it appears as part of an updater of a
  /// DesignatedInitUpdateExpr (see below). The base expression of a DIUE
  /// initializes a big object, and the NoInitExpr's mark the spots within the
  /// big object not to be overwritten by the updater.
  ///
  /// \see DesignatedInitUpdateExpr
  class NoInitExpr : public Expr {
  public:
    explicit NoInitExpr(QualType ty)
        : Expr(NoInitExprClass, ty, VK_PRValue, OK_Ordinary) {
      setDependence(computeDependence(this));
    }
  
    explicit NoInitExpr(EmptyShell Empty)
      : Expr(NoInitExprClass, Empty) { }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == NoInitExprClass;
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return SourceLocation(); }
    SourceLocation getEndLoc() const LLVM_READONLY { return SourceLocation(); }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  // In cases like:
  //   struct Q { int a, b, c; };
  //   Q *getQ();
  //   void foo() {
  //     struct A { Q q; } a = { *getQ(), .q.b = 3 };
  //   }
  //
  // We will have an InitListExpr for a, with type A, and then a
  // DesignatedInitUpdateExpr for "a.q" with type Q. The "base" for this DIUE
  // is the call expression *getQ(); the "updater" for the DIUE is ".q.b = 3"
  //
  class DesignatedInitUpdateExpr : public Expr {
    // BaseAndUpdaterExprs[0] is the base expression;
    // BaseAndUpdaterExprs[1] is an InitListExpr overwriting part of the base.
    Stmt *BaseAndUpdaterExprs[2];
  
  public:
    DesignatedInitUpdateExpr(const ASTContext &C, SourceLocation lBraceLoc,
                             Expr *baseExprs, SourceLocation rBraceLoc);
  
    explicit DesignatedInitUpdateExpr(EmptyShell Empty)
      : Expr(DesignatedInitUpdateExprClass, Empty) { }
  
    SourceLocation getBeginLoc() const LLVM_READONLY;
    SourceLocation getEndLoc() const LLVM_READONLY;
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == DesignatedInitUpdateExprClass;
    }
  
    Expr *getBase() const { return cast<Expr>(BaseAndUpdaterExprs[0]); }
    void setBase(Expr *Base) { BaseAndUpdaterExprs[0] = Base; }
  
    InitListExpr *getUpdater() const {
      return cast<InitListExpr>(BaseAndUpdaterExprs[1]);
    }
    void setUpdater(Expr *Updater) { BaseAndUpdaterExprs[1] = Updater; }
  
    // Iterators
    // children = the base and the updater
    child_range children() {
      return child_range(&BaseAndUpdaterExprs[0], &BaseAndUpdaterExprs[0] + 2);
    }
    const_child_range children() const {
      return const_child_range(&BaseAndUpdaterExprs[0],
                               &BaseAndUpdaterExprs[0] + 2);
    }
  };
  
  /// Represents a loop initializing the elements of an array.
  ///
  /// The need to initialize the elements of an array occurs in a number of
  /// contexts:
  ///
  ///  * in the implicit copy/move constructor for a class with an array member
  ///  * when a lambda-expression captures an array by value
  ///  * when a decomposition declaration decomposes an array
  ///
  /// There are two subexpressions: a common expression (the source array)
  /// that is evaluated once up-front, and a per-element initializer that
  /// runs once for each array element.
  ///
  /// Within the per-element initializer, the common expression may be referenced
  /// via an OpaqueValueExpr, and the current index may be obtained via an
  /// ArrayInitIndexExpr.
  class ArrayInitLoopExpr : public Expr {
    Stmt *SubExprs[2];
  
    explicit ArrayInitLoopExpr(EmptyShell Empty)
        : Expr(ArrayInitLoopExprClass, Empty), SubExprs{} {}
  
  public:
    explicit ArrayInitLoopExpr(QualType T, Expr *CommonInit, Expr *ElementInit)
        : Expr(ArrayInitLoopExprClass, T, VK_PRValue, OK_Ordinary),
          SubExprs{CommonInit, ElementInit} {
      setDependence(computeDependence(this));
    }
  
    /// Get the common subexpression shared by all initializations (the source
    /// array).
    OpaqueValueExpr *getCommonExpr() const {
      return cast<OpaqueValueExpr>(SubExprs[0]);
    }
  
    /// Get the initializer to use for each array element.
    Expr *getSubExpr() const { return cast<Expr>(SubExprs[1]); }
  
    llvm::APInt getArraySize() const {
      return cast<ConstantArrayType>(getType()->castAsArrayTypeUnsafe())
          ->getSize();
    }
  
    static bool classof(const Stmt *S) {
      return S->getStmtClass() == ArrayInitLoopExprClass;
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getCommonExpr()->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getCommonExpr()->getEndLoc();
    }
  
    child_range children() {
      return child_range(SubExprs, SubExprs + 2);
    }
    const_child_range children() const {
      return const_child_range(SubExprs, SubExprs + 2);
    }
  
    friend class ASTReader;
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
  };
  
  /// Represents the index of the current element of an array being
  /// initialized by an ArrayInitLoopExpr. This can only appear within the
  /// subexpression of an ArrayInitLoopExpr.
  class ArrayInitIndexExpr : public Expr {
    explicit ArrayInitIndexExpr(EmptyShell Empty)
        : Expr(ArrayInitIndexExprClass, Empty) {}
  
  public:
    explicit ArrayInitIndexExpr(QualType T)
        : Expr(ArrayInitIndexExprClass, T, VK_PRValue, OK_Ordinary) {
      setDependence(ExprDependence::None);
    }
  
    static bool classof(const Stmt *S) {
      return S->getStmtClass() == ArrayInitIndexExprClass;
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return SourceLocation(); }
    SourceLocation getEndLoc() const LLVM_READONLY { return SourceLocation(); }
  
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  
    friend class ASTReader;
    friend class ASTStmtReader;
  };
  
  /// Represents an implicitly-generated value initialization of
  /// an object of a given type.
  ///
  /// Implicit value initializations occur within semantic initializer
  /// list expressions (InitListExpr) as placeholders for subobject
  /// initializations not explicitly specified by the user.
  ///
  /// \see InitListExpr
  class ImplicitValueInitExpr : public Expr {
  public:
    explicit ImplicitValueInitExpr(QualType ty)
        : Expr(ImplicitValueInitExprClass, ty, VK_PRValue, OK_Ordinary) {
      setDependence(computeDependence(this));
    }
  
    /// Construct an empty implicit value initialization.
    explicit ImplicitValueInitExpr(EmptyShell Empty)
      : Expr(ImplicitValueInitExprClass, Empty) { }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ImplicitValueInitExprClass;
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return SourceLocation(); }
    SourceLocation getEndLoc() const LLVM_READONLY { return SourceLocation(); }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  class ParenListExpr final
      : public Expr,
        private llvm::TrailingObjects<ParenListExpr, Stmt *> {
    friend class ASTStmtReader;
    friend TrailingObjects;
  
    /// The location of the left and right parentheses.
    SourceLocation LParenLoc, RParenLoc;
  
    /// Build a paren list.
    ParenListExpr(SourceLocation LParenLoc, ArrayRef<Expr *> Exprs,
                  SourceLocation RParenLoc);
  
    /// Build an empty paren list.
    ParenListExpr(EmptyShell Empty, unsigned NumExprs);
  
  public:
    /// Create a paren list.
    static ParenListExpr *Create(const ASTContext &Ctx, SourceLocation LParenLoc,
                                 ArrayRef<Expr *> Exprs,
                                 SourceLocation RParenLoc);
  
    /// Create an empty paren list.
    static ParenListExpr *CreateEmpty(const ASTContext &Ctx, unsigned NumExprs);
  
    /// Return the number of expressions in this paren list.
    unsigned getNumExprs() const { return ParenListExprBits.NumExprs; }
  
    Expr *getExpr(unsigned Init) {
      assert(Init < getNumExprs() && "Initializer access out of range!");
      return getExprs()[Init];
    }
  
    const Expr *getExpr(unsigned Init) const {
      return const_cast<ParenListExpr *>(this)->getExpr(Init);
    }
  
    Expr **getExprs() {
      return reinterpret_cast<Expr **>(getTrailingObjects<Stmt *>());
    }
  
    ArrayRef<Expr *> exprs() {
      return llvm::makeArrayRef(getExprs(), getNumExprs());
    }
  
    SourceLocation getLParenLoc() const { return LParenLoc; }
    SourceLocation getRParenLoc() const { return RParenLoc; }
    SourceLocation getBeginLoc() const { return getLParenLoc(); }
    SourceLocation getEndLoc() const { return getRParenLoc(); }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ParenListExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(getTrailingObjects<Stmt *>(),
                         getTrailingObjects<Stmt *>() + getNumExprs());
    }
    const_child_range children() const {
      return const_child_range(getTrailingObjects<Stmt *>(),
                               getTrailingObjects<Stmt *>() + getNumExprs());
    }
  };
  
  /// Represents a C11 generic selection.
  ///
  /// A generic selection (C11 6.5.1.1) contains an unevaluated controlling
  /// expression, followed by one or more generic associations.  Each generic
  /// association specifies a type name and an expression, or "default" and an
  /// expression (in which case it is known as a default generic association).
  /// The type and value of the generic selection are identical to those of its
  /// result expression, which is defined as the expression in the generic
  /// association with a type name that is compatible with the type of the
  /// controlling expression, or the expression in the default generic association
  /// if no types are compatible.  For example:
  ///
  /// @code
  /// _Generic(X, double: 1, float: 2, default: 3)
  /// @endcode
  ///
  /// The above expression evaluates to 1 if 1.0 is substituted for X, 2 if 1.0f
  /// or 3 if "hello".
  ///
  /// As an extension, generic selections are allowed in C++, where the following
  /// additional semantics apply:
  ///
  /// Any generic selection whose controlling expression is type-dependent or
  /// which names a dependent type in its association list is result-dependent,
  /// which means that the choice of result expression is dependent.
  /// Result-dependent generic associations are both type- and value-dependent.
  class GenericSelectionExpr final
      : public Expr,
        private llvm::TrailingObjects<GenericSelectionExpr, Stmt *,
                                      TypeSourceInfo *> {
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
    friend TrailingObjects;
  
    /// The number of association expressions and the index of the result
    /// expression in the case where the generic selection expression is not
    /// result-dependent. The result index is equal to ResultDependentIndex
    /// if and only if the generic selection expression is result-dependent.
    unsigned NumAssocs, ResultIndex;
    enum : unsigned {
      ResultDependentIndex = std::numeric_limits<unsigned>::max(),
      ControllingIndex = 0,
      AssocExprStartIndex = 1
    };
  
    /// The location of the "default" and of the right parenthesis.
    SourceLocation DefaultLoc, RParenLoc;
  
    // GenericSelectionExpr is followed by several trailing objects.
    // They are (in order):
    //
    // * A single Stmt * for the controlling expression.
    // * An array of getNumAssocs() Stmt * for the association expressions.
    // * An array of getNumAssocs() TypeSourceInfo *, one for each of the
    //   association expressions.
    unsigned numTrailingObjects(OverloadToken<Stmt *>) const {
      // Add one to account for the controlling expression; the remainder
      // are the associated expressions.
      return 1 + getNumAssocs();
    }
  
    unsigned numTrailingObjects(OverloadToken<TypeSourceInfo *>) const {
      return getNumAssocs();
    }
  
    template <bool Const> class AssociationIteratorTy;
    /// Bundle together an association expression and its TypeSourceInfo.
    /// The Const template parameter is for the const and non-const versions
    /// of AssociationTy.
    template <bool Const> class AssociationTy {
      friend class GenericSelectionExpr;
      template <bool OtherConst> friend class AssociationIteratorTy;
      using ExprPtrTy = std::conditional_t<Const, const Expr *, Expr *>;
      using TSIPtrTy =
          std::conditional_t<Const, const TypeSourceInfo *, TypeSourceInfo *>;
      ExprPtrTy E;
      TSIPtrTy TSI;
      bool Selected;
      AssociationTy(ExprPtrTy E, TSIPtrTy TSI, bool Selected)
          : E(E), TSI(TSI), Selected(Selected) {}
  
    public:
      ExprPtrTy getAssociationExpr() const { return E; }
      TSIPtrTy getTypeSourceInfo() const { return TSI; }
      QualType getType() const { return TSI ? TSI->getType() : QualType(); }
      bool isSelected() const { return Selected; }
      AssociationTy *operator->() { return this; }
      const AssociationTy *operator->() const { return this; }
    }; // class AssociationTy
  
    /// Iterator over const and non-const Association objects. The Association
    /// objects are created on the fly when the iterator is dereferenced.
    /// This abstract over how exactly the association expressions and the
    /// corresponding TypeSourceInfo * are stored.
    template <bool Const>
    class AssociationIteratorTy
        : public llvm::iterator_facade_base<
              AssociationIteratorTy<Const>, std::input_iterator_tag,
              AssociationTy<Const>, std::ptrdiff_t, AssociationTy<Const>,
              AssociationTy<Const>> {
      friend class GenericSelectionExpr;
      // FIXME: This iterator could conceptually be a random access iterator, and
      // it would be nice if we could strengthen the iterator category someday.
      // However this iterator does not satisfy two requirements of forward
      // iterators:
      // a) reference = T& or reference = const T&
      // b) If It1 and It2 are both dereferenceable, then It1 == It2 if and only
      //    if *It1 and *It2 are bound to the same objects.
      // An alternative design approach was discussed during review;
      // store an Association object inside the iterator, and return a reference
      // to it when dereferenced. This idea was discarded beacuse of nasty
      // lifetime issues:
      //    AssociationIterator It = ...;
      //    const Association &Assoc = *It++; // Oops, Assoc is dangling.
      using BaseTy = typename AssociationIteratorTy::iterator_facade_base;
      using StmtPtrPtrTy =
          std::conditional_t<Const, const Stmt *const *, Stmt **>;
      using TSIPtrPtrTy = std::conditional_t<Const, const TypeSourceInfo *const *,
                                             TypeSourceInfo **>;
      StmtPtrPtrTy E; // = nullptr; FIXME: Once support for gcc 4.8 is dropped.
      TSIPtrPtrTy TSI; // Kept in sync with E.
      unsigned Offset = 0, SelectedOffset = 0;
      AssociationIteratorTy(StmtPtrPtrTy E, TSIPtrPtrTy TSI, unsigned Offset,
                            unsigned SelectedOffset)
          : E(E), TSI(TSI), Offset(Offset), SelectedOffset(SelectedOffset) {}
  
    public:
      AssociationIteratorTy() : E(nullptr), TSI(nullptr) {}
      typename BaseTy::reference operator*() const {
        return AssociationTy<Const>(cast<Expr>(*E), *TSI,
                                    Offset == SelectedOffset);
      }
      typename BaseTy::pointer operator->() const { return **this; }
      using BaseTy::operator++;
      AssociationIteratorTy &operator++() {
        ++E;
        ++TSI;
        ++Offset;
        return *this;
      }
      bool operator==(AssociationIteratorTy Other) const { return E == Other.E; }
    }; // class AssociationIterator
  
    /// Build a non-result-dependent generic selection expression.
    GenericSelectionExpr(const ASTContext &Context, SourceLocation GenericLoc,
                         Expr *ControllingExpr,
                         ArrayRef<TypeSourceInfo *> AssocTypes,
                         ArrayRef<Expr *> AssocExprs, SourceLocation DefaultLoc,
                         SourceLocation RParenLoc,
                         bool ContainsUnexpandedParameterPack,
                         unsigned ResultIndex);
  
    /// Build a result-dependent generic selection expression.
    GenericSelectionExpr(const ASTContext &Context, SourceLocation GenericLoc,
                         Expr *ControllingExpr,
                         ArrayRef<TypeSourceInfo *> AssocTypes,
                         ArrayRef<Expr *> AssocExprs, SourceLocation DefaultLoc,
                         SourceLocation RParenLoc,
                         bool ContainsUnexpandedParameterPack);
  
    /// Build an empty generic selection expression for deserialization.
    explicit GenericSelectionExpr(EmptyShell Empty, unsigned NumAssocs);
  
  public:
    /// Create a non-result-dependent generic selection expression.
    static GenericSelectionExpr *
    Create(const ASTContext &Context, SourceLocation GenericLoc,
           Expr *ControllingExpr, ArrayRef<TypeSourceInfo *> AssocTypes,
           ArrayRef<Expr *> AssocExprs, SourceLocation DefaultLoc,
           SourceLocation RParenLoc, bool ContainsUnexpandedParameterPack,
           unsigned ResultIndex);
  
    /// Create a result-dependent generic selection expression.
    static GenericSelectionExpr *
    Create(const ASTContext &Context, SourceLocation GenericLoc,
           Expr *ControllingExpr, ArrayRef<TypeSourceInfo *> AssocTypes,
           ArrayRef<Expr *> AssocExprs, SourceLocation DefaultLoc,
           SourceLocation RParenLoc, bool ContainsUnexpandedParameterPack);
  
    /// Create an empty generic selection expression for deserialization.
    static GenericSelectionExpr *CreateEmpty(const ASTContext &Context,
                                             unsigned NumAssocs);
  
    using Association = AssociationTy<false>;
    using ConstAssociation = AssociationTy<true>;
    using AssociationIterator = AssociationIteratorTy<false>;
    using ConstAssociationIterator = AssociationIteratorTy<true>;
    using association_range = llvm::iterator_range<AssociationIterator>;
    using const_association_range =
        llvm::iterator_range<ConstAssociationIterator>;
  
    /// The number of association expressions.
    unsigned getNumAssocs() const { return NumAssocs; }
  
    /// The zero-based index of the result expression's generic association in
    /// the generic selection's association list.  Defined only if the
    /// generic selection is not result-dependent.
    unsigned getResultIndex() const {
      assert(!isResultDependent() &&
             "Generic selection is result-dependent but getResultIndex called!");
      return ResultIndex;
    }
  
    /// Whether this generic selection is result-dependent.
    bool isResultDependent() const { return ResultIndex == ResultDependentIndex; }
  
    /// Return the controlling expression of this generic selection expression.
    Expr *getControllingExpr() {
      return cast<Expr>(getTrailingObjects<Stmt *>()[ControllingIndex]);
    }
    const Expr *getControllingExpr() const {
      return cast<Expr>(getTrailingObjects<Stmt *>()[ControllingIndex]);
    }
  
    /// Return the result expression of this controlling expression. Defined if
    /// and only if the generic selection expression is not result-dependent.
    Expr *getResultExpr() {
      return cast<Expr>(
          getTrailingObjects<Stmt *>()[AssocExprStartIndex + getResultIndex()]);
    }
    const Expr *getResultExpr() const {
      return cast<Expr>(
          getTrailingObjects<Stmt *>()[AssocExprStartIndex + getResultIndex()]);
    }
  
    ArrayRef<Expr *> getAssocExprs() const {
      return {reinterpret_cast<Expr *const *>(getTrailingObjects<Stmt *>() +
                                              AssocExprStartIndex),
              NumAssocs};
    }
    ArrayRef<TypeSourceInfo *> getAssocTypeSourceInfos() const {
      return {getTrailingObjects<TypeSourceInfo *>(), NumAssocs};
    }
  
    /// Return the Ith association expression with its TypeSourceInfo,
    /// bundled together in GenericSelectionExpr::(Const)Association.
    Association getAssociation(unsigned I) {
      assert(I < getNumAssocs() &&
             "Out-of-range index in GenericSelectionExpr::getAssociation!");
      return Association(
          cast<Expr>(getTrailingObjects<Stmt *>()[AssocExprStartIndex + I]),
          getTrailingObjects<TypeSourceInfo *>()[I],
          !isResultDependent() && (getResultIndex() == I));
    }
    ConstAssociation getAssociation(unsigned I) const {
      assert(I < getNumAssocs() &&
             "Out-of-range index in GenericSelectionExpr::getAssociation!");
      return ConstAssociation(
          cast<Expr>(getTrailingObjects<Stmt *>()[AssocExprStartIndex + I]),
          getTrailingObjects<TypeSourceInfo *>()[I],
          !isResultDependent() && (getResultIndex() == I));
    }
  
    association_range associations() {
      AssociationIterator Begin(getTrailingObjects<Stmt *>() +
                                    AssocExprStartIndex,
                                getTrailingObjects<TypeSourceInfo *>(),
                                /*Offset=*/0, ResultIndex);
      AssociationIterator End(Begin.E + NumAssocs, Begin.TSI + NumAssocs,
                              /*Offset=*/NumAssocs, ResultIndex);
      return llvm::make_range(Begin, End);
    }
  
    const_association_range associations() const {
      ConstAssociationIterator Begin(getTrailingObjects<Stmt *>() +
                                         AssocExprStartIndex,
                                     getTrailingObjects<TypeSourceInfo *>(),
                                     /*Offset=*/0, ResultIndex);
      ConstAssociationIterator End(Begin.E + NumAssocs, Begin.TSI + NumAssocs,
                                   /*Offset=*/NumAssocs, ResultIndex);
      return llvm::make_range(Begin, End);
    }
  
    SourceLocation getGenericLoc() const {
      return GenericSelectionExprBits.GenericLoc;
    }
    SourceLocation getDefaultLoc() const { return DefaultLoc; }
    SourceLocation getRParenLoc() const { return RParenLoc; }
    SourceLocation getBeginLoc() const { return getGenericLoc(); }
    SourceLocation getEndLoc() const { return getRParenLoc(); }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == GenericSelectionExprClass;
    }
  
    child_range children() {
      return child_range(getTrailingObjects<Stmt *>(),
                         getTrailingObjects<Stmt *>() +
                             numTrailingObjects(OverloadToken<Stmt *>()));
    }
    const_child_range children() const {
      return const_child_range(getTrailingObjects<Stmt *>(),
                               getTrailingObjects<Stmt *>() +
                                   numTrailingObjects(OverloadToken<Stmt *>()));
    }
  };
  
  //===----------------------------------------------------------------------===//
  // Clang Extensions
  //===----------------------------------------------------------------------===//
  
  /// ExtVectorElementExpr - This represents access to specific elements of a
  /// vector, and may occur on the left hand side or right hand side.  For example
  /// the following is legal:  "V.xy = V.zw" if V is a 4 element extended vector.
  ///
  /// Note that the base may have either vector or pointer to vector type, just
  /// like a struct field reference.
  ///
  class ExtVectorElementExpr : public Expr {
    Stmt *Base;
    IdentifierInfo *Accessor;
    SourceLocation AccessorLoc;
  public:
    ExtVectorElementExpr(QualType ty, ExprValueKind VK, Expr *base,
                         IdentifierInfo &accessor, SourceLocation loc)
        : Expr(ExtVectorElementExprClass, ty, VK,
               (VK == VK_PRValue ? OK_Ordinary : OK_VectorComponent)),
          Base(base), Accessor(&accessor), AccessorLoc(loc) {
      setDependence(computeDependence(this));
    }
  
    /// Build an empty vector element expression.
    explicit ExtVectorElementExpr(EmptyShell Empty)
      : Expr(ExtVectorElementExprClass, Empty) { }
  
    const Expr *getBase() const { return cast<Expr>(Base); }
    Expr *getBase() { return cast<Expr>(Base); }
    void setBase(Expr *E) { Base = E; }
  
    IdentifierInfo &getAccessor() const { return *Accessor; }
    void setAccessor(IdentifierInfo *II) { Accessor = II; }
  
    SourceLocation getAccessorLoc() const { return AccessorLoc; }
    void setAccessorLoc(SourceLocation L) { AccessorLoc = L; }
  
    /// getNumElements - Get the number of components being selected.
    unsigned getNumElements() const;
  
    /// containsDuplicateElements - Return true if any element access is
    /// repeated.
    bool containsDuplicateElements() const;
  
    /// getEncodedElementAccess - Encode the elements accessed into an llvm
    /// aggregate Constant of ConstantInt(s).
    void getEncodedElementAccess(SmallVectorImpl<uint32_t> &Elts) const;
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getBase()->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY { return AccessorLoc; }
  
    /// isArrow - Return true if the base expression is a pointer to vector,
    /// return false if the base expression is a vector.
    bool isArrow() const;
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == ExtVectorElementExprClass;
    }
  
    // Iterators
    child_range children() { return child_range(&Base, &Base+1); }
    const_child_range children() const {
      return const_child_range(&Base, &Base + 1);
    }
  };
  
  /// BlockExpr - Adaptor class for mixing a BlockDecl with expressions.
  /// ^{ statement-body }   or   ^(int arg1, float arg2){ statement-body }
  class BlockExpr : public Expr {
  protected:
    BlockDecl *TheBlock;
  public:
    BlockExpr(BlockDecl *BD, QualType ty)
        : Expr(BlockExprClass, ty, VK_PRValue, OK_Ordinary), TheBlock(BD) {
      setDependence(computeDependence(this));
    }
  
    /// Build an empty block expression.
    explicit BlockExpr(EmptyShell Empty) : Expr(BlockExprClass, Empty) { }
  
    const BlockDecl *getBlockDecl() const { return TheBlock; }
    BlockDecl *getBlockDecl() { return TheBlock; }
    void setBlockDecl(BlockDecl *BD) { TheBlock = BD; }
  
    // Convenience functions for probing the underlying BlockDecl.
    SourceLocation getCaretLocation() const;
    const Stmt *getBody() const;
    Stmt *getBody();
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getCaretLocation();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getBody()->getEndLoc();
    }
  
    /// getFunctionType - Return the underlying function type for this block.
    const FunctionProtoType *getFunctionType() const;
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == BlockExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  };
  
  /// Copy initialization expr of a __block variable and a boolean flag that
  /// indicates whether the expression can throw.
  struct BlockVarCopyInit {
    BlockVarCopyInit() = default;
    BlockVarCopyInit(Expr *CopyExpr, bool CanThrow)
        : ExprAndFlag(CopyExpr, CanThrow) {}
    void setExprAndFlag(Expr *CopyExpr, bool CanThrow) {
      ExprAndFlag.setPointerAndInt(CopyExpr, CanThrow);
    }
    Expr *getCopyExpr() const { return ExprAndFlag.getPointer(); }
    bool canThrow() const { return ExprAndFlag.getInt(); }
    llvm::PointerIntPair<Expr *, 1, bool> ExprAndFlag;
  };
  
  /// AsTypeExpr - Clang builtin function __builtin_astype [OpenCL 6.2.4.2]
  /// This AST node provides support for reinterpreting a type to another
  /// type of the same size.
  class AsTypeExpr : public Expr {
  private:
    Stmt *SrcExpr;
    SourceLocation BuiltinLoc, RParenLoc;
  
    friend class ASTReader;
    friend class ASTStmtReader;
    explicit AsTypeExpr(EmptyShell Empty) : Expr(AsTypeExprClass, Empty) {}
  
  public:
    AsTypeExpr(Expr *SrcExpr, QualType DstType, ExprValueKind VK,
               ExprObjectKind OK, SourceLocation BuiltinLoc,
               SourceLocation RParenLoc)
        : Expr(AsTypeExprClass, DstType, VK, OK), SrcExpr(SrcExpr),
          BuiltinLoc(BuiltinLoc), RParenLoc(RParenLoc) {
      setDependence(computeDependence(this));
    }
  
    /// getSrcExpr - Return the Expr to be converted.
    Expr *getSrcExpr() const { return cast<Expr>(SrcExpr); }
  
    /// getBuiltinLoc - Return the location of the __builtin_astype token.
    SourceLocation getBuiltinLoc() const { return BuiltinLoc; }
  
    /// getRParenLoc - Return the location of final right parenthesis.
    SourceLocation getRParenLoc() const { return RParenLoc; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return BuiltinLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == AsTypeExprClass;
    }
  
    // Iterators
    child_range children() { return child_range(&SrcExpr, &SrcExpr+1); }
    const_child_range children() const {
      return const_child_range(&SrcExpr, &SrcExpr + 1);
    }
  };
  
  /// PseudoObjectExpr - An expression which accesses a pseudo-object
  /// l-value.  A pseudo-object is an abstract object, accesses to which
  /// are translated to calls.  The pseudo-object expression has a
  /// syntactic form, which shows how the expression was actually
  /// written in the source code, and a semantic form, which is a series
  /// of expressions to be executed in order which detail how the
  /// operation is actually evaluated.  Optionally, one of the semantic
  /// forms may also provide a result value for the expression.
  ///
  /// If any of the semantic-form expressions is an OpaqueValueExpr,
  /// that OVE is required to have a source expression, and it is bound
  /// to the result of that source expression.  Such OVEs may appear
  /// only in subsequent semantic-form expressions and as
  /// sub-expressions of the syntactic form.
  ///
  /// PseudoObjectExpr should be used only when an operation can be
  /// usefully described in terms of fairly simple rewrite rules on
  /// objects and functions that are meant to be used by end-developers.
  /// For example, under the Itanium ABI, dynamic casts are implemented
  /// as a call to a runtime function called __dynamic_cast; using this
  /// class to describe that would be inappropriate because that call is
  /// not really part of the user-visible semantics, and instead the
  /// cast is properly reflected in the AST and IR-generation has been
  /// taught to generate the call as necessary.  In contrast, an
  /// Objective-C property access is semantically defined to be
  /// equivalent to a particular message send, and this is very much
  /// part of the user model.  The name of this class encourages this
  /// modelling design.
  class PseudoObjectExpr final
      : public Expr,
        private llvm::TrailingObjects<PseudoObjectExpr, Expr *> {
    // PseudoObjectExprBits.NumSubExprs - The number of sub-expressions.
    // Always at least two, because the first sub-expression is the
    // syntactic form.
  
    // PseudoObjectExprBits.ResultIndex - The index of the
    // sub-expression holding the result.  0 means the result is void,
    // which is unambiguous because it's the index of the syntactic
    // form.  Note that this is therefore 1 higher than the value passed
    // in to Create, which is an index within the semantic forms.
    // Note also that ASTStmtWriter assumes this encoding.
  
    Expr **getSubExprsBuffer() { return getTrailingObjects<Expr *>(); }
    const Expr * const *getSubExprsBuffer() const {
      return getTrailingObjects<Expr *>();
    }
  
    PseudoObjectExpr(QualType type, ExprValueKind VK,
                     Expr *syntactic, ArrayRef<Expr*> semantic,
                     unsigned resultIndex);
  
    PseudoObjectExpr(EmptyShell shell, unsigned numSemanticExprs);
  
    unsigned getNumSubExprs() const {
      return PseudoObjectExprBits.NumSubExprs;
    }
  
  public:
    /// NoResult - A value for the result index indicating that there is
    /// no semantic result.
    enum : unsigned { NoResult = ~0U };
  
    static PseudoObjectExpr *Create(const ASTContext &Context, Expr *syntactic,
                                    ArrayRef<Expr*> semantic,
                                    unsigned resultIndex);
  
    static PseudoObjectExpr *Create(const ASTContext &Context, EmptyShell shell,
                                    unsigned numSemanticExprs);
  
    /// Return the syntactic form of this expression, i.e. the
    /// expression it actually looks like.  Likely to be expressed in
    /// terms of OpaqueValueExprs bound in the semantic form.
    Expr *getSyntacticForm() { return getSubExprsBuffer()[0]; }
    const Expr *getSyntacticForm() const { return getSubExprsBuffer()[0]; }
  
    /// Return the index of the result-bearing expression into the semantics
    /// expressions, or PseudoObjectExpr::NoResult if there is none.
    unsigned getResultExprIndex() const {
      if (PseudoObjectExprBits.ResultIndex == 0) return NoResult;
      return PseudoObjectExprBits.ResultIndex - 1;
    }
  
    /// Return the result-bearing expression, or null if there is none.
    Expr *getResultExpr() {
      if (PseudoObjectExprBits.ResultIndex == 0)
        return nullptr;
      return getSubExprsBuffer()[PseudoObjectExprBits.ResultIndex];
    }
    const Expr *getResultExpr() const {
      return const_cast<PseudoObjectExpr*>(this)->getResultExpr();
    }
  
    unsigned getNumSemanticExprs() const { return getNumSubExprs() - 1; }
  
    typedef Expr * const *semantics_iterator;
    typedef const Expr * const *const_semantics_iterator;
    semantics_iterator semantics_begin() {
      return getSubExprsBuffer() + 1;
    }
    const_semantics_iterator semantics_begin() const {
      return getSubExprsBuffer() + 1;
    }
    semantics_iterator semantics_end() {
      return getSubExprsBuffer() + getNumSubExprs();
    }
    const_semantics_iterator semantics_end() const {
      return getSubExprsBuffer() + getNumSubExprs();
    }
  
    llvm::iterator_range<semantics_iterator> semantics() {
      return llvm::make_range(semantics_begin(), semantics_end());
    }
    llvm::iterator_range<const_semantics_iterator> semantics() const {
      return llvm::make_range(semantics_begin(), semantics_end());
    }
  
    Expr *getSemanticExpr(unsigned index) {
      assert(index + 1 < getNumSubExprs());
      return getSubExprsBuffer()[index + 1];
    }
    const Expr *getSemanticExpr(unsigned index) const {
      return const_cast<PseudoObjectExpr*>(this)->getSemanticExpr(index);
    }
  
    SourceLocation getExprLoc() const LLVM_READONLY {
      return getSyntacticForm()->getExprLoc();
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY {
      return getSyntacticForm()->getBeginLoc();
    }
    SourceLocation getEndLoc() const LLVM_READONLY {
      return getSyntacticForm()->getEndLoc();
    }
  
    child_range children() {
      const_child_range CCR =
          const_cast<const PseudoObjectExpr *>(this)->children();
      return child_range(cast_away_const(CCR.begin()),
                         cast_away_const(CCR.end()));
    }
    const_child_range children() const {
      Stmt *const *cs = const_cast<Stmt *const *>(
          reinterpret_cast<const Stmt *const *>(getSubExprsBuffer()));
      return const_child_range(cs, cs + getNumSubExprs());
    }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == PseudoObjectExprClass;
    }
  
    friend TrailingObjects;
    friend class ASTStmtReader;
  };
  
  /// AtomicExpr - Variadic atomic builtins: __atomic_exchange, __atomic_fetch_*,
  /// __atomic_load, __atomic_store, and __atomic_compare_exchange_*, for the
  /// similarly-named C++11 instructions, and __c11 variants for <stdatomic.h>,
  /// and corresponding __opencl_atomic_* for OpenCL 2.0.
  /// All of these instructions take one primary pointer, at least one memory
  /// order. The instructions for which getScopeModel returns non-null value
  /// take one synch scope.
  class AtomicExpr : public Expr {
  public:
    enum AtomicOp {
  #define BUILTIN(ID, TYPE, ATTRS)
  #define ATOMIC_BUILTIN(ID, TYPE, ATTRS) AO ## ID,
  #include "clang/Basic/Builtins.def"
      // Avoid trailing comma
      BI_First = 0
    };
  
  private:
    /// Location of sub-expressions.
    /// The location of Scope sub-expression is NumSubExprs - 1, which is
    /// not fixed, therefore is not defined in enum.
    enum { PTR, ORDER, VAL1, ORDER_FAIL, VAL2, WEAK, END_EXPR };
    Stmt *SubExprs[END_EXPR + 1];
    unsigned NumSubExprs;
    SourceLocation BuiltinLoc, RParenLoc;
    AtomicOp Op;
  
    friend class ASTStmtReader;
  public:
    AtomicExpr(SourceLocation BLoc, ArrayRef<Expr*> args, QualType t,
               AtomicOp op, SourceLocation RP);
  
    /// Determine the number of arguments the specified atomic builtin
    /// should have.
    static unsigned getNumSubExprs(AtomicOp Op);
  
    /// Build an empty AtomicExpr.
    explicit AtomicExpr(EmptyShell Empty) : Expr(AtomicExprClass, Empty) { }
  
    Expr *getPtr() const {
      return cast<Expr>(SubExprs[PTR]);
    }
    Expr *getOrder() const {
      return cast<Expr>(SubExprs[ORDER]);
    }
    Expr *getScope() const {
      assert(getScopeModel() && "No scope");
      return cast<Expr>(SubExprs[NumSubExprs - 1]);
    }
    Expr *getVal1() const {
      if (Op == AO__c11_atomic_init || Op == AO__opencl_atomic_init)
        return cast<Expr>(SubExprs[ORDER]);
      assert(NumSubExprs > VAL1);
      return cast<Expr>(SubExprs[VAL1]);
    }
    Expr *getOrderFail() const {
      assert(NumSubExprs > ORDER_FAIL);
      return cast<Expr>(SubExprs[ORDER_FAIL]);
    }
    Expr *getVal2() const {
      if (Op == AO__atomic_exchange)
        return cast<Expr>(SubExprs[ORDER_FAIL]);
      assert(NumSubExprs > VAL2);
      return cast<Expr>(SubExprs[VAL2]);
    }
    Expr *getWeak() const {
      assert(NumSubExprs > WEAK);
      return cast<Expr>(SubExprs[WEAK]);
    }
    QualType getValueType() const;
  
    AtomicOp getOp() const { return Op; }
    unsigned getNumSubExprs() const { return NumSubExprs; }
  
    Expr **getSubExprs() { return reinterpret_cast<Expr **>(SubExprs); }
    const Expr * const *getSubExprs() const {
      return reinterpret_cast<Expr * const *>(SubExprs);
    }
  
    bool isVolatile() const {
      return getPtr()->getType()->getPointeeType().isVolatileQualified();
    }
  
    bool isCmpXChg() const {
      return getOp() == AO__c11_atomic_compare_exchange_strong ||
             getOp() == AO__c11_atomic_compare_exchange_weak ||
             getOp() == AO__opencl_atomic_compare_exchange_strong ||
             getOp() == AO__opencl_atomic_compare_exchange_weak ||
             getOp() == AO__atomic_compare_exchange ||
             getOp() == AO__atomic_compare_exchange_n;
    }
  
    bool isOpenCL() const {
      return getOp() >= AO__opencl_atomic_init &&
             getOp() <= AO__opencl_atomic_fetch_max;
    }
  
    SourceLocation getBuiltinLoc() const { return BuiltinLoc; }
    SourceLocation getRParenLoc() const { return RParenLoc; }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return BuiltinLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == AtomicExprClass;
    }
  
    // Iterators
    child_range children() {
      return child_range(SubExprs, SubExprs+NumSubExprs);
    }
    const_child_range children() const {
      return const_child_range(SubExprs, SubExprs + NumSubExprs);
    }
  
    /// Get atomic scope model for the atomic op code.
    /// \return empty atomic scope model if the atomic op code does not have
    ///   scope operand.
    static std::unique_ptr<AtomicScopeModel> getScopeModel(AtomicOp Op) {
      auto Kind =
          (Op >= AO__opencl_atomic_load && Op <= AO__opencl_atomic_fetch_max)
              ? AtomicScopeModelKind::OpenCL
              : AtomicScopeModelKind::None;
      return AtomicScopeModel::create(Kind);
    }
  
    /// Get atomic scope model.
    /// \return empty atomic scope model if this atomic expression does not have
    ///   scope operand.
    std::unique_ptr<AtomicScopeModel> getScopeModel() const {
      return getScopeModel(getOp());
    }
  };
  
  /// TypoExpr - Internal placeholder for expressions where typo correction
  /// still needs to be performed and/or an error diagnostic emitted.
  class TypoExpr : public Expr {
    // The location for the typo name.
    SourceLocation TypoLoc;
  
  public:
    TypoExpr(QualType T, SourceLocation TypoLoc)
        : Expr(TypoExprClass, T, VK_LValue, OK_Ordinary), TypoLoc(TypoLoc) {
      assert(T->isDependentType() && "TypoExpr given a non-dependent type");
      setDependence(ExprDependence::TypeValueInstantiation |
                    ExprDependence::Error);
    }
  
    child_range children() {
      return child_range(child_iterator(), child_iterator());
    }
    const_child_range children() const {
      return const_child_range(const_child_iterator(), const_child_iterator());
    }
  
    SourceLocation getBeginLoc() const LLVM_READONLY { return TypoLoc; }
    SourceLocation getEndLoc() const LLVM_READONLY { return TypoLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == TypoExprClass;
    }
  
  };
  
  /// Frontend produces RecoveryExprs on semantic errors that prevent creating
  /// other well-formed expressions. E.g. when type-checking of a binary operator
  /// fails, we cannot produce a BinaryOperator expression. Instead, we can choose
  /// to produce a recovery expression storing left and right operands.
  ///
  /// RecoveryExpr does not have any semantic meaning in C++, it is only useful to
  /// preserve expressions in AST that would otherwise be dropped. It captures
  /// subexpressions of some expression that we could not construct and source
  /// range covered by the expression.
  ///
  /// By default, RecoveryExpr uses dependence-bits to take advantage of existing
  /// machinery to deal with dependent code in C++, e.g. RecoveryExpr is preserved
  /// in `decltype(<broken-expr>)` as part of the `DependentDecltypeType`. In
  /// addition to that, clang does not report most errors on dependent
  /// expressions, so we get rid of bogus errors for free. However, note that
  /// unlike other dependent expressions, RecoveryExpr can be produced in
  /// non-template contexts.
  ///
  /// We will preserve the type in RecoveryExpr when the type is known, e.g.
  /// preserving the return type for a broken non-overloaded function call, a
  /// overloaded call where all candidates have the same return type. In this
  /// case, the expression is not type-dependent (unless the known type is itself
  /// dependent)
  ///
  /// One can also reliably suppress all bogus errors on expressions containing
  /// recovery expressions by examining results of Expr::containsErrors().
  class RecoveryExpr final : public Expr,
                             private llvm::TrailingObjects<RecoveryExpr, Expr *> {
  public:
    static RecoveryExpr *Create(ASTContext &Ctx, QualType T,
                                SourceLocation BeginLoc, SourceLocation EndLoc,
                                ArrayRef<Expr *> SubExprs);
    static RecoveryExpr *CreateEmpty(ASTContext &Ctx, unsigned NumSubExprs);
  
    ArrayRef<Expr *> subExpressions() {
      auto *B = getTrailingObjects<Expr *>();
      return llvm::makeArrayRef(B, B + NumExprs);
    }
  
    ArrayRef<const Expr *> subExpressions() const {
      return const_cast<RecoveryExpr *>(this)->subExpressions();
    }
  
    child_range children() {
      Stmt **B = reinterpret_cast<Stmt **>(getTrailingObjects<Expr *>());
      return child_range(B, B + NumExprs);
    }
  
    SourceLocation getBeginLoc() const { return BeginLoc; }
    SourceLocation getEndLoc() const { return EndLoc; }
  
    static bool classof(const Stmt *T) {
      return T->getStmtClass() == RecoveryExprClass;
    }
  
  private:
    RecoveryExpr(ASTContext &Ctx, QualType T, SourceLocation BeginLoc,
                 SourceLocation EndLoc, ArrayRef<Expr *> SubExprs);
    RecoveryExpr(EmptyShell Empty, unsigned NumSubExprs)
        : Expr(RecoveryExprClass, Empty), NumExprs(NumSubExprs) {}
  
    size_t numTrailingObjects(OverloadToken<Stmt *>) const { return NumExprs; }
  
    SourceLocation BeginLoc, EndLoc;
    unsigned NumExprs;
    friend TrailingObjects;
    friend class ASTStmtReader;
    friend class ASTStmtWriter;
  };
  
  } // end namespace clang
  
  #endif // LLVM_CLANG_AST_EXPR_H
  