Type.h

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//===- Type.h - C Language Family Type Representation -----------*- 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// C Language Family Type Representation
///
/// This file defines the clang::Type interface and subclasses, used to
/// represent types for languages in the C family.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_AST_TYPE_H
#define LLVM_CLANG_AST_TYPE_H
 
#include "clang/AST/DependenceFlags.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/AST/TemplateName.h"
#include "clang/Basic/AddressSpaces.h"
#include "clang/Basic/AttrKinds.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/ExceptionSpecificationType.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/Linkage.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Basic/Visibility.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/PointerLikeTypeTraits.h"
#include "llvm/Support/TrailingObjects.h"
#include "llvm/Support/type_traits.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <string>
#include <type_traits>
#include <utility>
 
namespace clang {
 
class ExtQuals;
class QualType;
class ConceptDecl;
class TagDecl;
class TemplateParameterList;
class Type;
 
enum {
  TypeAlignmentInBits = 4,
  TypeAlignment = 1 << TypeAlignmentInBits
};
 
namespace serialization {
  template <class T> class AbstractTypeReader;
  template <class T> class AbstractTypeWriter;
}
 
} // namespace clang
 
namespace llvm {
 
  template <typename T>
  struct PointerLikeTypeTraits;
  template<>
  struct PointerLikeTypeTraits< ::clang::Type*> {
    static inline void *getAsVoidPointer(::clang::Type *P) { return P; }
 
    static inline ::clang::Type *getFromVoidPointer(void *P) {
      return static_cast< ::clang::Type*>(P);
    }
 
    static constexpr int NumLowBitsAvailable = clang::TypeAlignmentInBits;
  };
 
  template<>
  struct PointerLikeTypeTraits< ::clang::ExtQuals*> {
    static inline void *getAsVoidPointer(::clang::ExtQuals *P) { return P; }
 
    static inline ::clang::ExtQuals *getFromVoidPointer(void *P) {
      return static_cast< ::clang::ExtQuals*>(P);
    }
 
    static constexpr int NumLowBitsAvailable = clang::TypeAlignmentInBits;
  };
 
} // namespace llvm
 
namespace clang {
 
class ASTContext;
template <typename> class CanQual;
class CXXRecordDecl;
class DeclContext;
class EnumDecl;
class Expr;
class ExtQualsTypeCommonBase;
class FunctionDecl;
class IdentifierInfo;
class NamedDecl;
class ObjCInterfaceDecl;
class ObjCProtocolDecl;
class ObjCTypeParamDecl;
struct PrintingPolicy;
class RecordDecl;
class Stmt;
class TagDecl;
class TemplateArgument;
class TemplateArgumentListInfo;
class TemplateArgumentLoc;
class TemplateTypeParmDecl;
class TypedefNameDecl;
class UnresolvedUsingTypenameDecl;
class UsingShadowDecl;
 
using CanQualType = CanQual<Type>;
 
// Provide forward declarations for all of the *Type classes.
#define TYPE(Class, Base) class Class##Type;
#include "clang/AST/TypeNodes.inc"
 
/// The collection of all-type qualifiers we support.
/// Clang supports five independent qualifiers:
/// * C99: const, volatile, and restrict
/// * MS: __unaligned
/// * Embedded C (TR18037): address spaces
/// * Objective C: the GC attributes (none, weak, or strong)
class Qualifiers {
public:
  enum TQ { // NOTE: These flags must be kept in sync with DeclSpec::TQ.
    Const    = 0x1,
    Restrict = 0x2,
    Volatile = 0x4,
    CVRMask = Const | Volatile | Restrict
  };
 
  enum GC {
    GCNone = 0,
    Weak,
    Strong
  };
 
  enum ObjCLifetime {
    /// There is no lifetime qualification on this type.
    OCL_None,
 
    /// This object can be modified without requiring retains or
    /// releases.
    OCL_ExplicitNone,
 
    /// Assigning into this object requires the old value to be
    /// released and the new value to be retained.  The timing of the
    /// release of the old value is inexact: it may be moved to
    /// immediately after the last known point where the value is
    /// live.
    OCL_Strong,
 
    /// Reading or writing from this object requires a barrier call.
    OCL_Weak,
 
    /// Assigning into this object requires a lifetime extension.
    OCL_Autoreleasing
  };
 
  enum {
    /// The maximum supported address space number.
    /// 23 bits should be enough for anyone.
    MaxAddressSpace = 0x7fffffu,
 
    /// The width of the "fast" qualifier mask.
    FastWidth = 3,
 
    /// The fast qualifier mask.
    FastMask = (1 << FastWidth) - 1
  };
 
  /// Returns the common set of qualifiers while removing them from
  /// the given sets.
  static Qualifiers removeCommonQualifiers(Qualifiers &L, Qualifiers &R) {
    // If both are only CVR-qualified, bit operations are sufficient.
    if (!(L.Mask & ~CVRMask) && !(R.Mask & ~CVRMask)) {
      Qualifiers Q;
      Q.Mask = L.Mask & R.Mask;
      L.Mask &= ~Q.Mask;
      R.Mask &= ~Q.Mask;
      return Q;
    }
 
    Qualifiers Q;
    unsigned CommonCRV = L.getCVRQualifiers() & R.getCVRQualifiers();
    Q.addCVRQualifiers(CommonCRV);
    L.removeCVRQualifiers(CommonCRV);
    R.removeCVRQualifiers(CommonCRV);
 
    if (L.getObjCGCAttr() == R.getObjCGCAttr()) {
      Q.setObjCGCAttr(L.getObjCGCAttr());
      L.removeObjCGCAttr();
      R.removeObjCGCAttr();
    }
 
    if (L.getObjCLifetime() == R.getObjCLifetime()) {
      Q.setObjCLifetime(L.getObjCLifetime());
      L.removeObjCLifetime();
      R.removeObjCLifetime();
    }
 
    if (L.getAddressSpace() == R.getAddressSpace()) {
      Q.setAddressSpace(L.getAddressSpace());
      L.removeAddressSpace();
      R.removeAddressSpace();
    }
    return Q;
  }
 
  static Qualifiers fromFastMask(unsigned Mask) {
    Qualifiers Qs;
    Qs.addFastQualifiers(Mask);
    return Qs;
  }
 
  static Qualifiers fromCVRMask(unsigned CVR) {
    Qualifiers Qs;
    Qs.addCVRQualifiers(CVR);
    return Qs;
  }
 
  static Qualifiers fromCVRUMask(unsigned CVRU) {
    Qualifiers Qs;
    Qs.addCVRUQualifiers(CVRU);
    return Qs;
  }
 
  // Deserialize qualifiers from an opaque representation.
  static Qualifiers fromOpaqueValue(unsigned opaque) {
    Qualifiers Qs;
    Qs.Mask = opaque;
    return Qs;
  }
 
  // Serialize these qualifiers into an opaque representation.
  unsigned getAsOpaqueValue() const {
    return Mask;
  }
 
  bool hasConst() const { return Mask & Const; }
  bool hasOnlyConst() const { return Mask == Const; }
  void removeConst() { Mask &= ~Const; }
  void addConst() { Mask |= Const; }
 
  bool hasVolatile() const { return Mask & Volatile; }
  bool hasOnlyVolatile() const { return Mask == Volatile; }
  void removeVolatile() { Mask &= ~Volatile; }
  void addVolatile() { Mask |= Volatile; }
 
  bool hasRestrict() const { return Mask & Restrict; }
  bool hasOnlyRestrict() const { return Mask == Restrict; }
  void removeRestrict() { Mask &= ~Restrict; }
  void addRestrict() { Mask |= Restrict; }
 
  bool hasCVRQualifiers() const { return getCVRQualifiers(); }
  unsigned getCVRQualifiers() const { return Mask & CVRMask; }
  unsigned getCVRUQualifiers() const { return Mask & (CVRMask | UMask); }
 
  void setCVRQualifiers(unsigned mask) {
    assert(!(mask & ~CVRMask) && "bitmask contains non-CVR bits");
    Mask = (Mask & ~CVRMask) | mask;
  }
  void removeCVRQualifiers(unsigned mask) {
    assert(!(mask & ~CVRMask) && "bitmask contains non-CVR bits");
    Mask &= ~mask;
  }
  void removeCVRQualifiers() {
    removeCVRQualifiers(CVRMask);
  }
  void addCVRQualifiers(unsigned mask) {
    assert(!(mask & ~CVRMask) && "bitmask contains non-CVR bits");
    Mask |= mask;
  }
  void addCVRUQualifiers(unsigned mask) {
    assert(!(mask & ~CVRMask & ~UMask) && "bitmask contains non-CVRU bits");
    Mask |= mask;
  }
 
  bool hasUnaligned() const { return Mask & UMask; }
  void setUnaligned(bool flag) {
    Mask = (Mask & ~UMask) | (flag ? UMask : 0);
  }
  void removeUnaligned() { Mask &= ~UMask; }
  void addUnaligned() { Mask |= UMask; }
 
  bool hasObjCGCAttr() const { return Mask & GCAttrMask; }
  GC getObjCGCAttr() const { return GC((Mask & GCAttrMask) >> GCAttrShift); }
  void setObjCGCAttr(GC type) {
    Mask = (Mask & ~GCAttrMask) | (type << GCAttrShift);
  }
  void removeObjCGCAttr() { setObjCGCAttr(GCNone); }
  void addObjCGCAttr(GC type) {
    assert(type);
    setObjCGCAttr(type);
  }
  Qualifiers withoutObjCGCAttr() const {
    Qualifiers qs = *this;
    qs.removeObjCGCAttr();
    return qs;
  }
  Qualifiers withoutObjCLifetime() const {
    Qualifiers qs = *this;
    qs.removeObjCLifetime();
    return qs;
  }
  Qualifiers withoutAddressSpace() const {
    Qualifiers qs = *this;
    qs.removeAddressSpace();
    return qs;
  }
 
  bool hasObjCLifetime() const { return Mask & LifetimeMask; }
  ObjCLifetime getObjCLifetime() const {
    return ObjCLifetime((Mask & LifetimeMask) >> LifetimeShift);
  }
  void setObjCLifetime(ObjCLifetime type) {
    Mask = (Mask & ~LifetimeMask) | (type << LifetimeShift);
  }
  void removeObjCLifetime() { setObjCLifetime(OCL_None); }
  void addObjCLifetime(ObjCLifetime type) {
    assert(type);
    assert(!hasObjCLifetime());
    Mask |= (type << LifetimeShift);
  }
 
  /// True if the lifetime is neither None or ExplicitNone.
  bool hasNonTrivialObjCLifetime() const {
    ObjCLifetime lifetime = getObjCLifetime();
    return (lifetime > OCL_ExplicitNone);
  }
 
  /// True if the lifetime is either strong or weak.
  bool hasStrongOrWeakObjCLifetime() const {
    ObjCLifetime lifetime = getObjCLifetime();
    return (lifetime == OCL_Strong || lifetime == OCL_Weak);
  }
 
  bool hasAddressSpace() const { return Mask & AddressSpaceMask; }
  LangAS getAddressSpace() const {
    return static_cast<LangAS>(Mask >> AddressSpaceShift);
  }
  bool hasTargetSpecificAddressSpace() const {
    return isTargetAddressSpace(getAddressSpace());
  }
  /// Get the address space attribute value to be printed by diagnostics.
  unsigned getAddressSpaceAttributePrintValue() const {
    auto Addr = getAddressSpace();
    // This function is not supposed to be used with language specific
    // address spaces. If that happens, the diagnostic message should consider
    // printing the QualType instead of the address space value.
    assert(Addr == LangAS::Default || hasTargetSpecificAddressSpace());
    if (Addr != LangAS::Default)
      return toTargetAddressSpace(Addr);
    // TODO: The diagnostic messages where Addr may be 0 should be fixed
    // since it cannot differentiate the situation where 0 denotes the default
    // address space or user specified __attribute__((address_space(0))).
    return 0;
  }
  void setAddressSpace(LangAS space) {
    assert((unsigned)space <= MaxAddressSpace);
    Mask = (Mask & ~AddressSpaceMask)
         | (((uint32_t) space) << AddressSpaceShift);
  }
  void removeAddressSpace() { setAddressSpace(LangAS::Default); }
  void addAddressSpace(LangAS space) {
    assert(space != LangAS::Default);
    setAddressSpace(space);
  }
 
  // Fast qualifiers are those that can be allocated directly
  // on a QualType object.
  bool hasFastQualifiers() const { return getFastQualifiers(); }
  unsigned getFastQualifiers() const { return Mask & FastMask; }
  void setFastQualifiers(unsigned mask) {
    assert(!(mask & ~FastMask) && "bitmask contains non-fast qualifier bits");
    Mask = (Mask & ~FastMask) | mask;
  }
  void removeFastQualifiers(unsigned mask) {
    assert(!(mask & ~FastMask) && "bitmask contains non-fast qualifier bits");
    Mask &= ~mask;
  }
  void removeFastQualifiers() {
    removeFastQualifiers(FastMask);
  }
  void addFastQualifiers(unsigned mask) {
    assert(!(mask & ~FastMask) && "bitmask contains non-fast qualifier bits");
    Mask |= mask;
  }
 
  /// Return true if the set contains any qualifiers which require an ExtQuals
  /// node to be allocated.
  bool hasNonFastQualifiers() const { return Mask & ~FastMask; }
  Qualifiers getNonFastQualifiers() const {
    Qualifiers Quals = *this;
    Quals.setFastQualifiers(0);
    return Quals;
  }
 
  /// Return true if the set contains any qualifiers.
  bool hasQualifiers() const { return Mask; }
  bool empty() const { return !Mask; }
 
  /// Add the qualifiers from the given set to this set.
  void addQualifiers(Qualifiers Q) {
    // If the other set doesn't have any non-boolean qualifiers, just
    // bit-or it in.
    if (!(Q.Mask & ~CVRMask))
      Mask |= Q.Mask;
    else {
      Mask |= (Q.Mask & CVRMask);
      if (Q.hasAddressSpace())
        addAddressSpace(Q.getAddressSpace());
      if (Q.hasObjCGCAttr())
        addObjCGCAttr(Q.getObjCGCAttr());
      if (Q.hasObjCLifetime())
        addObjCLifetime(Q.getObjCLifetime());
    }
  }
 
  /// Remove the qualifiers from the given set from this set.
  void removeQualifiers(Qualifiers Q) {
    // If the other set doesn't have any non-boolean qualifiers, just
    // bit-and the inverse in.
    if (!(Q.Mask & ~CVRMask))
      Mask &= ~Q.Mask;
    else {
      Mask &= ~(Q.Mask & CVRMask);
      if (getObjCGCAttr() == Q.getObjCGCAttr())
        removeObjCGCAttr();
      if (getObjCLifetime() == Q.getObjCLifetime())
        removeObjCLifetime();
      if (getAddressSpace() == Q.getAddressSpace())
        removeAddressSpace();
    }
  }
 
  /// Add the qualifiers from the given set to this set, given that
  /// they don't conflict.
  void addConsistentQualifiers(Qualifiers qs) {
    assert(getAddressSpace() == qs.getAddressSpace() ||
           !hasAddressSpace() || !qs.hasAddressSpace());
    assert(getObjCGCAttr() == qs.getObjCGCAttr() ||
           !hasObjCGCAttr() || !qs.hasObjCGCAttr());
    assert(getObjCLifetime() == qs.getObjCLifetime() ||
           !hasObjCLifetime() || !qs.hasObjCLifetime());
    Mask |= qs.Mask;
  }
 
  /// Returns true if address space A is equal to or a superset of B.
  /// OpenCL v2.0 defines conversion rules (OpenCLC v2.0 s6.5.5) and notion of
  /// overlapping address spaces.
  /// CL1.1 or CL1.2:
  ///   every address space is a superset of itself.
  /// CL2.0 adds:
  ///   __generic is a superset of any address space except for __constant.
  static bool isAddressSpaceSupersetOf(LangAS A, LangAS B) {
    // Address spaces must match exactly.
    return A == B ||
           // Otherwise in OpenCLC v2.0 s6.5.5: every address space except
           // for __constant can be used as __generic.
           (A == LangAS::opencl_generic && B != LangAS::opencl_constant) ||
           // We also define global_device and global_host address spaces,
           // to distinguish global pointers allocated on host from pointers
           // allocated on device, which are a subset of __global.
           (A == LangAS::opencl_global && (B == LangAS::opencl_global_device ||
                                           B == LangAS::opencl_global_host)) ||
           (A == LangAS::sycl_global && (B == LangAS::sycl_global_device ||
                                         B == LangAS::sycl_global_host)) ||
           // Consider pointer size address spaces to be equivalent to default.
           ((isPtrSizeAddressSpace(A) || A == LangAS::Default) &&
            (isPtrSizeAddressSpace(B) || B == LangAS::Default)) ||
           // Default is a superset of SYCL address spaces.
           (A == LangAS::Default &&
            (B == LangAS::sycl_private || B == LangAS::sycl_local ||
             B == LangAS::sycl_global || B == LangAS::sycl_global_device ||
             B == LangAS::sycl_global_host)) ||
           // In HIP device compilation, any cuda address space is allowed
           // to implicitly cast into the default address space.
           (A == LangAS::Default &&
            (B == LangAS::cuda_constant || B == LangAS::cuda_device ||
             B == LangAS::cuda_shared));
  }
 
  /// Returns true if the address space in these qualifiers is equal to or
  /// a superset of the address space in the argument qualifiers.
  bool isAddressSpaceSupersetOf(Qualifiers other) const {
    return isAddressSpaceSupersetOf(getAddressSpace(), other.getAddressSpace());
  }
 
  /// Determines if these qualifiers compatibly include another set.
  /// Generally this answers the question of whether an object with the other
  /// qualifiers can be safely used as an object with these qualifiers.
  bool compatiblyIncludes(Qualifiers other) const {
    return isAddressSpaceSupersetOf(other) &&
           // ObjC GC qualifiers can match, be added, or be removed, but can't
           // be changed.
           (getObjCGCAttr() == other.getObjCGCAttr() || !hasObjCGCAttr() ||
            !other.hasObjCGCAttr()) &&
           // ObjC lifetime qualifiers must match exactly.
           getObjCLifetime() == other.getObjCLifetime() &&
           // CVR qualifiers may subset.
           (((Mask & CVRMask) | (other.Mask & CVRMask)) == (Mask & CVRMask)) &&
           // U qualifier may superset.
           (!other.hasUnaligned() || hasUnaligned());
  }
 
  /// Determines if these qualifiers compatibly include another set of
  /// qualifiers from the narrow perspective of Objective-C ARC lifetime.
  ///
  /// One set of Objective-C lifetime qualifiers compatibly includes the other
  /// if the lifetime qualifiers match, or if both are non-__weak and the
  /// including set also contains the 'const' qualifier, or both are non-__weak
  /// and one is None (which can only happen in non-ARC modes).
  bool compatiblyIncludesObjCLifetime(Qualifiers other) const {
    if (getObjCLifetime() == other.getObjCLifetime())
      return true;
 
    if (getObjCLifetime() == OCL_Weak || other.getObjCLifetime() == OCL_Weak)
      return false;
 
    if (getObjCLifetime() == OCL_None || other.getObjCLifetime() == OCL_None)
      return true;
 
    return hasConst();
  }
 
  /// Determine whether this set of qualifiers is a strict superset of
  /// another set of qualifiers, not considering qualifier compatibility.
  bool isStrictSupersetOf(Qualifiers Other) const;
 
  bool operator==(Qualifiers Other) const { return Mask == Other.Mask; }
  bool operator!=(Qualifiers Other) const { return Mask != Other.Mask; }
 
  explicit operator bool() const { return hasQualifiers(); }
 
  Qualifiers &operator+=(Qualifiers R) {
    addQualifiers(R);
    return *this;
  }
 
  // Union two qualifier sets.  If an enumerated qualifier appears
  // in both sets, use the one from the right.
  friend Qualifiers operator+(Qualifiers L, Qualifiers R) {
    L += R;
    return L;
  }
 
  Qualifiers &operator-=(Qualifiers R) {
    removeQualifiers(R);
    return *this;
  }
 
  /// Compute the difference between two qualifier sets.
  friend Qualifiers operator-(Qualifiers L, Qualifiers R) {
    L -= R;
    return L;
  }
 
  std::string getAsString() const;
  std::string getAsString(const PrintingPolicy &Policy) const;
 
  static std::string getAddrSpaceAsString(LangAS AS);
 
  bool isEmptyWhenPrinted(const PrintingPolicy &Policy) const;
  void print(raw_ostream &OS, const PrintingPolicy &Policy,
             bool appendSpaceIfNonEmpty = false) const;
 
  void Profile(llvm::FoldingSetNodeID &ID) const {
    ID.AddInteger(Mask);
  }
 
private:
  // bits:     |0 1 2|3|4 .. 5|6  ..  8|9   ...   31|
  //           |C R V|U|GCAttr|Lifetime|AddressSpace|
  uint32_t Mask = 0;
 
  static const uint32_t UMask = 0x8;
  static const uint32_t UShift = 3;
  static const uint32_t GCAttrMask = 0x30;
  static const uint32_t GCAttrShift = 4;
  static const uint32_t LifetimeMask = 0x1C0;
  static const uint32_t LifetimeShift = 6;
  static const uint32_t AddressSpaceMask =
      ~(CVRMask | UMask | GCAttrMask | LifetimeMask);
  static const uint32_t AddressSpaceShift = 9;
};
 
/// A std::pair-like structure for storing a qualified type split
/// into its local qualifiers and its locally-unqualified type.
struct SplitQualType {
  /// The locally-unqualified type.
  const Type *Ty = nullptr;
 
  /// The local qualifiers.
  Qualifiers Quals;
 
  SplitQualType() = default;
  SplitQualType(const Type *ty, Qualifiers qs) : Ty(ty), Quals(qs) {}
 
  SplitQualType getSingleStepDesugaredType() const; // end of this file
 
  // Make std::tie work.
  std::pair<const Type *,Qualifiers> asPair() const {
    return std::pair<const Type *, Qualifiers>(Ty, Quals);
  }
 
  friend bool operator==(SplitQualType a, SplitQualType b) {
    return a.Ty == b.Ty && a.Quals == b.Quals;
  }
  friend bool operator!=(SplitQualType a, SplitQualType b) {
    return a.Ty != b.Ty || a.Quals != b.Quals;
  }
};
 
/// The kind of type we are substituting Objective-C type arguments into.
///
/// The kind of substitution affects the replacement of type parameters when
/// no concrete type information is provided, e.g., when dealing with an
/// unspecialized type.
enum class ObjCSubstitutionContext {
  /// An ordinary type.
  Ordinary,
 
  /// The result type of a method or function.
  Result,
 
  /// The parameter type of a method or function.
  Parameter,
 
  /// The type of a property.
  Property,
 
  /// The superclass of a type.
  Superclass,
};
 
/// A (possibly-)qualified type.
///
/// For efficiency, we don't store CV-qualified types as nodes on their
/// own: instead each reference to a type stores the qualifiers.  This
/// greatly reduces the number of nodes we need to allocate for types (for
/// example we only need one for 'int', 'const int', 'volatile int',
/// 'const volatile int', etc).
///
/// As an added efficiency bonus, instead of making this a pair, we
/// just store the two bits we care about in the low bits of the
/// pointer.  To handle the packing/unpacking, we make QualType be a
/// simple wrapper class that acts like a smart pointer.  A third bit
/// indicates whether there are extended qualifiers present, in which
/// case the pointer points to a special structure.
class QualType {
  friend class QualifierCollector;
 
  // Thankfully, these are efficiently composable.
  llvm::PointerIntPair<llvm::PointerUnion<const Type *, const ExtQuals *>,
                       Qualifiers::FastWidth> Value;
 
  const ExtQuals *getExtQualsUnsafe() const {
    return Value.getPointer().get<const ExtQuals*>();
  }
 
  const Type *getTypePtrUnsafe() const {
    return Value.getPointer().get<const Type*>();
  }
 
  const ExtQualsTypeCommonBase *getCommonPtr() const {
    assert(!isNull() && "Cannot retrieve a NULL type pointer");
    auto CommonPtrVal = reinterpret_cast<uintptr_t>(Value.getOpaqueValue());
    CommonPtrVal &= ~(uintptr_t)((1 << TypeAlignmentInBits) - 1);
    return reinterpret_cast<ExtQualsTypeCommonBase*>(CommonPtrVal);
  }
 
public:
  QualType() = default;
  QualType(const Type *Ptr, unsigned Quals) : Value(Ptr, Quals) {}
  QualType(const ExtQuals *Ptr, unsigned Quals) : Value(Ptr, Quals) {}
 
  unsigned getLocalFastQualifiers() const { return Value.getInt(); }
  void setLocalFastQualifiers(unsigned Quals) { Value.setInt(Quals); }
 
  /// Retrieves a pointer to the underlying (unqualified) type.
  ///
  /// This function requires that the type not be NULL. If the type might be
  /// NULL, use the (slightly less efficient) \c getTypePtrOrNull().
  const Type *getTypePtr() const;
 
  const Type *getTypePtrOrNull() const;
 
  /// Retrieves a pointer to the name of the base type.
  const IdentifierInfo *getBaseTypeIdentifier() const;
 
  /// Divides a QualType into its unqualified type and a set of local
  /// qualifiers.
  SplitQualType split() const;
 
  void *getAsOpaquePtr() const { return Value.getOpaqueValue(); }
 
  static QualType getFromOpaquePtr(const void *Ptr) {
    QualType T;
    T.Value.setFromOpaqueValue(const_cast<void*>(Ptr));
    return T;
  }
 
  const Type &operator*() const {
    return *getTypePtr();
  }
 
  const Type *operator->() const {
    return getTypePtr();
  }
 
  bool isCanonical() const;
  bool isCanonicalAsParam() const;
 
  /// Return true if this QualType doesn't point to a type yet.
  bool isNull() const {
    return Value.getPointer().isNull();
  }
 
  /// Determine whether this particular QualType instance has the
  /// "const" qualifier set, without looking through typedefs that may have
  /// added "const" at a different level.
  bool isLocalConstQualified() const {
    return (getLocalFastQualifiers() & Qualifiers::Const);
  }
 
  /// Determine whether this type is const-qualified.
  bool isConstQualified() const;
 
  /// Determine whether this particular QualType instance has the
  /// "restrict" qualifier set, without looking through typedefs that may have
  /// added "restrict" at a different level.
  bool isLocalRestrictQualified() const {
    return (getLocalFastQualifiers() & Qualifiers::Restrict);
  }
 
  /// Determine whether this type is restrict-qualified.
  bool isRestrictQualified() const;
 
  /// Determine whether this particular QualType instance has the
  /// "volatile" qualifier set, without looking through typedefs that may have
  /// added "volatile" at a different level.
  bool isLocalVolatileQualified() const {
    return (getLocalFastQualifiers() & Qualifiers::Volatile);
  }
 
  /// Determine whether this type is volatile-qualified.
  bool isVolatileQualified() const;
 
  /// Determine whether this particular QualType instance has any
  /// qualifiers, without looking through any typedefs that might add
  /// qualifiers at a different level.
  bool hasLocalQualifiers() const {
    return getLocalFastQualifiers() || hasLocalNonFastQualifiers();
  }
 
  /// Determine whether this type has any qualifiers.
  bool hasQualifiers() const;
 
  /// Determine whether this particular QualType instance has any
  /// "non-fast" qualifiers, e.g., those that are stored in an ExtQualType
  /// instance.
  bool hasLocalNonFastQualifiers() const {
    return Value.getPointer().is<const ExtQuals*>();
  }
 
  /// Retrieve the set of qualifiers local to this particular QualType
  /// instance, not including any qualifiers acquired through typedefs or
  /// other sugar.
  Qualifiers getLocalQualifiers() const;
 
  /// Retrieve the set of qualifiers applied to this type.
  Qualifiers getQualifiers() const;
 
  /// Retrieve the set of CVR (const-volatile-restrict) qualifiers
  /// local to this particular QualType instance, not including any qualifiers
  /// acquired through typedefs or other sugar.
  unsigned getLocalCVRQualifiers() const {
    return getLocalFastQualifiers();
  }
 
  /// Retrieve the set of CVR (const-volatile-restrict) qualifiers
  /// applied to this type.
  unsigned getCVRQualifiers() const;
 
  bool isConstant(const ASTContext& Ctx) const {
    return QualType::isConstant(*this, Ctx);
  }
 
  /// Determine whether this is a Plain Old Data (POD) type (C++ 3.9p10).
  bool isPODType(const ASTContext &Context) const;
 
  /// Return true if this is a POD type according to the rules of the C++98
  /// standard, regardless of the current compilation's language.
  bool isCXX98PODType(const ASTContext &Context) const;
 
  /// Return true if this is a POD type according to the more relaxed rules
  /// of the C++11 standard, regardless of the current compilation's language.
  /// (C++0x [basic.types]p9). Note that, unlike
  /// CXXRecordDecl::isCXX11StandardLayout, this takes DRs into account.
  bool isCXX11PODType(const ASTContext &Context) const;
 
  /// Return true if this is a trivial type per (C++0x [basic.types]p9)
  bool isTrivialType(const ASTContext &Context) const;
 
  /// Return true if this is a trivially copyable type (C++0x [basic.types]p9)
  bool isTriviallyCopyableType(const ASTContext &Context) const;
 
 
  /// Returns true if it is a class and it might be dynamic.
  bool mayBeDynamicClass() const;
 
  /// Returns true if it is not a class or if the class might not be dynamic.
  bool mayBeNotDynamicClass() const;
 
  // Don't promise in the API that anything besides 'const' can be
  // easily added.
 
  /// Add the `const` type qualifier to this QualType.
  void addConst() {
    addFastQualifiers(Qualifiers::Const);
  }
  QualType withConst() const {
    return withFastQualifiers(Qualifiers::Const);
  }
 
  /// Add the `volatile` type qualifier to this QualType.
  void addVolatile() {
    addFastQualifiers(Qualifiers::Volatile);
  }
  QualType withVolatile() const {
    return withFastQualifiers(Qualifiers::Volatile);
  }
 
  /// Add the `restrict` qualifier to this QualType.
  void addRestrict() {
    addFastQualifiers(Qualifiers::Restrict);
  }
  QualType withRestrict() const {
    return withFastQualifiers(Qualifiers::Restrict);
  }
 
  QualType withCVRQualifiers(unsigned CVR) const {
    return withFastQualifiers(CVR);
  }
 
  void addFastQualifiers(unsigned TQs) {
    assert(!(TQs & ~Qualifiers::FastMask)
           && "non-fast qualifier bits set in mask!");
    Value.setInt(Value.getInt() | TQs);
  }
 
  void removeLocalConst();
  void removeLocalVolatile();
  void removeLocalRestrict();
  void removeLocalCVRQualifiers(unsigned Mask);
 
  void removeLocalFastQualifiers() { Value.setInt(0); }
  void removeLocalFastQualifiers(unsigned Mask) {
    assert(!(Mask & ~Qualifiers::FastMask) && "mask has non-fast qualifiers");
    Value.setInt(Value.getInt() & ~Mask);
  }
 
  // Creates a type with the given qualifiers in addition to any
  // qualifiers already on this type.
  QualType withFastQualifiers(unsigned TQs) const {
    QualType T = *this;
    T.addFastQualifiers(TQs);
    return T;
  }
 
  // Creates a type with exactly the given fast qualifiers, removing
  // any existing fast qualifiers.
  QualType withExactLocalFastQualifiers(unsigned TQs) const {
    return withoutLocalFastQualifiers().withFastQualifiers(TQs);
  }
 
  // Removes fast qualifiers, but leaves any extended qualifiers in place.
  QualType withoutLocalFastQualifiers() const {
    QualType T = *this;
    T.removeLocalFastQualifiers();
    return T;
  }
 
  QualType getCanonicalType() const;
 
  /// Return this type with all of the instance-specific qualifiers
  /// removed, but without removing any qualifiers that may have been applied
  /// through typedefs.
  QualType getLocalUnqualifiedType() const { return QualType(getTypePtr(), 0); }
 
  /// Retrieve the unqualified variant of the given type,
  /// removing as little sugar as possible.
  ///
  /// This routine looks through various kinds of sugar to find the
  /// least-desugared type that is unqualified. For example, given:
  ///
  /// \code
  /// typedef int Integer;
  /// typedef const Integer CInteger;
  /// typedef CInteger DifferenceType;
  /// \endcode
  ///
  /// Executing \c getUnqualifiedType() on the type \c DifferenceType will
  /// desugar until we hit the type \c Integer, which has no qualifiers on it.
  ///
  /// The resulting type might still be qualified if it's sugar for an array
  /// type.  To strip qualifiers even from within a sugared array type, use
  /// ASTContext::getUnqualifiedArrayType.
  inline QualType getUnqualifiedType() const;
 
  /// Retrieve the unqualified variant of the given type, removing as little
  /// sugar as possible.
  ///
  /// Like getUnqualifiedType(), but also returns the set of
  /// qualifiers that were built up.
  ///
  /// The resulting type might still be qualified if it's sugar for an array
  /// type.  To strip qualifiers even from within a sugared array type, use
  /// ASTContext::getUnqualifiedArrayType.
  inline SplitQualType getSplitUnqualifiedType() const;
 
  /// Determine whether this type is more qualified than the other
  /// given type, requiring exact equality for non-CVR qualifiers.
  bool isMoreQualifiedThan(QualType Other) const;
 
  /// Determine whether this type is at least as qualified as the other
  /// given type, requiring exact equality for non-CVR qualifiers.
  bool isAtLeastAsQualifiedAs(QualType Other) const;
 
  QualType getNonReferenceType() const;
 
  /// Determine the type of a (typically non-lvalue) expression with the
  /// specified result type.
  ///
  /// This routine should be used for expressions for which the return type is
  /// explicitly specified (e.g., in a cast or call) and isn't necessarily
  /// an lvalue. It removes a top-level reference (since there are no
  /// expressions of reference type) and deletes top-level cvr-qualifiers
  /// from non-class types (in C++) or all types (in C).
  QualType getNonLValueExprType(const ASTContext &Context) const;
 
  /// Remove an outer pack expansion type (if any) from this type. Used as part
  /// of converting the type of a declaration to the type of an expression that
  /// references that expression. It's meaningless for an expression to have a
  /// pack expansion type.
  QualType getNonPackExpansionType() const;
 
  /// Return the specified type with any "sugar" removed from
  /// the type.  This takes off typedefs, typeof's etc.  If the outer level of
  /// the type is already concrete, it returns it unmodified.  This is similar
  /// to getting the canonical type, but it doesn't remove *all* typedefs.  For
  /// example, it returns "T*" as "T*", (not as "int*"), because the pointer is
  /// concrete.
  ///
  /// Qualifiers are left in place.
  QualType getDesugaredType(const ASTContext &Context) const {
    return getDesugaredType(*this, Context);
  }
 
  SplitQualType getSplitDesugaredType() const {
    return getSplitDesugaredType(*this);
  }
 
  /// Return the specified type with one level of "sugar" removed from
  /// the type.
  ///
  /// This routine takes off the first typedef, typeof, etc. If the outer level
  /// of the type is already concrete, it returns it unmodified.
  QualType getSingleStepDesugaredType(const ASTContext &Context) const {
    return getSingleStepDesugaredTypeImpl(*this, Context);
  }
 
  /// Returns the specified type after dropping any
  /// outer-level parentheses.
  QualType IgnoreParens() const {
    if (isa<ParenType>(*this))
      return QualType::IgnoreParens(*this);
    return *this;
  }
 
  /// Indicate whether the specified types and qualifiers are identical.
  friend bool operator==(const QualType &LHS, const QualType &RHS) {
    return LHS.Value == RHS.Value;
  }
  friend bool operator!=(const QualType &LHS, const QualType &RHS) {
    return LHS.Value != RHS.Value;
  }
  friend bool operator<(const QualType &LHS, const QualType &RHS) {
    return LHS.Value < RHS.Value;
  }
 
  static std::string getAsString(SplitQualType split,
                                 const PrintingPolicy &Policy) {
    return getAsString(split.Ty, split.Quals, Policy);
  }
  static std::string getAsString(const Type *ty, Qualifiers qs,
                                 const PrintingPolicy &Policy);
 
  std::string getAsString() const;
  std::string getAsString(const PrintingPolicy &Policy) const;
 
  void print(raw_ostream &OS, const PrintingPolicy &Policy,
             const Twine &PlaceHolder = Twine(),
             unsigned Indentation = 0) const;
 
  static void print(SplitQualType split, raw_ostream &OS,
                    const PrintingPolicy &policy, const Twine &PlaceHolder,
                    unsigned Indentation = 0) {
    return print(split.Ty, split.Quals, OS, policy, PlaceHolder, Indentation);
  }
 
  static void print(const Type *ty, Qualifiers qs,
                    raw_ostream &OS, const PrintingPolicy &policy,
                    const Twine &PlaceHolder,
                    unsigned Indentation = 0);
 
  void getAsStringInternal(std::string &Str,
                           const PrintingPolicy &Policy) const;
 
  static void getAsStringInternal(SplitQualType split, std::string &out,
                                  const PrintingPolicy &policy) {
    return getAsStringInternal(split.Ty, split.Quals, out, policy);
  }
 
  static void getAsStringInternal(const Type *ty, Qualifiers qs,
                                  std::string &out,
                                  const PrintingPolicy &policy);
 
  class StreamedQualTypeHelper {
    const QualType &T;
    const PrintingPolicy &Policy;
    const Twine &PlaceHolder;
    unsigned Indentation;
 
  public:
    StreamedQualTypeHelper(const QualType &T, const PrintingPolicy &Policy,
                           const Twine &PlaceHolder, unsigned Indentation)
        : T(T), Policy(Policy), PlaceHolder(PlaceHolder),
          Indentation(Indentation) {}
 
    friend raw_ostream &operator<<(raw_ostream &OS,
                                   const StreamedQualTypeHelper &SQT) {
      SQT.T.print(OS, SQT.Policy, SQT.PlaceHolder, SQT.Indentation);
      return OS;
    }
  };
 
  StreamedQualTypeHelper stream(const PrintingPolicy &Policy,
                                const Twine &PlaceHolder = Twine(),
                                unsigned Indentation = 0) const {
    return StreamedQualTypeHelper(*this, Policy, PlaceHolder, Indentation);
  }
 
  void dump(const char *s) const;
  void dump() const;
  void dump(llvm::raw_ostream &OS, const ASTContext &Context) const;
 
  void Profile(llvm::FoldingSetNodeID &ID) const {
    ID.AddPointer(getAsOpaquePtr());
  }
 
  /// Check if this type has any address space qualifier.
  inline bool hasAddressSpace() const;
 
  /// Return the address space of this type.
  inline LangAS getAddressSpace() const;
 
  /// Returns true if address space qualifiers overlap with T address space
  /// qualifiers.
  /// OpenCL C defines conversion rules for pointers to different address spaces
  /// and notion of overlapping address spaces.
  /// CL1.1 or CL1.2:
  ///   address spaces overlap iff they are they same.
  /// OpenCL C v2.0 s6.5.5 adds:
  ///   __generic overlaps with any address space except for __constant.
  bool isAddressSpaceOverlapping(QualType T) const {
    Qualifiers Q = getQualifiers();
    Qualifiers TQ = T.getQualifiers();
    // Address spaces overlap if at least one of them is a superset of another
    return Q.isAddressSpaceSupersetOf(TQ) || TQ.isAddressSpaceSupersetOf(Q);
  }
 
  /// Returns gc attribute of this type.
  inline Qualifiers::GC getObjCGCAttr() const;
 
  /// true when Type is objc's weak.
  bool isObjCGCWeak() const {
    return getObjCGCAttr() == Qualifiers::Weak;
  }
 
  /// true when Type is objc's strong.
  bool isObjCGCStrong() const {
    return getObjCGCAttr() == Qualifiers::Strong;
  }
 
  /// Returns lifetime attribute of this type.
  Qualifiers::ObjCLifetime getObjCLifetime() const {
    return getQualifiers().getObjCLifetime();
  }
 
  bool hasNonTrivialObjCLifetime() const {
    return getQualifiers().hasNonTrivialObjCLifetime();
  }
 
  bool hasStrongOrWeakObjCLifetime() const {
    return getQualifiers().hasStrongOrWeakObjCLifetime();
  }
 
  // true when Type is objc's weak and weak is enabled but ARC isn't.
  bool isNonWeakInMRRWithObjCWeak(const ASTContext &Context) const;
 
  enum PrimitiveDefaultInitializeKind {
    /// The type does not fall into any of the following categories. Note that
    /// this case is zero-valued so that values of this enum can be used as a
    /// boolean condition for non-triviality.
    PDIK_Trivial,
 
    /// The type is an Objective-C retainable pointer type that is qualified
    /// with the ARC __strong qualifier.
    PDIK_ARCStrong,
 
    /// The type is an Objective-C retainable pointer type that is qualified
    /// with the ARC __weak qualifier.
    PDIK_ARCWeak,
 
    /// The type is a struct containing a field whose type is not PCK_Trivial.
    PDIK_Struct
  };
 
  /// Functions to query basic properties of non-trivial C struct types.
 
  /// Check if this is a non-trivial type that would cause a C struct
  /// transitively containing this type to be non-trivial to default initialize
  /// and return the kind.
  PrimitiveDefaultInitializeKind
  isNonTrivialToPrimitiveDefaultInitialize() const;
 
  enum PrimitiveCopyKind {
    /// The type does not fall into any of the following categories. Note that
    /// this case is zero-valued so that values of this enum can be used as a
    /// boolean condition for non-triviality.
    PCK_Trivial,
 
    /// The type would be trivial except that it is volatile-qualified. Types
    /// that fall into one of the other non-trivial cases may additionally be
    /// volatile-qualified.
    PCK_VolatileTrivial,
 
    /// The type is an Objective-C retainable pointer type that is qualified
    /// with the ARC __strong qualifier.
    PCK_ARCStrong,
 
    /// The type is an Objective-C retainable pointer type that is qualified
    /// with the ARC __weak qualifier.
    PCK_ARCWeak,
 
    /// The type is a struct containing a field whose type is neither
    /// PCK_Trivial nor PCK_VolatileTrivial.
    /// Note that a C++ struct type does not necessarily match this; C++ copying
    /// semantics are too complex to express here, in part because they depend
    /// on the exact constructor or assignment operator that is chosen by
    /// overload resolution to do the copy.
    PCK_Struct
  };
 
  /// Check if this is a non-trivial type that would cause a C struct
  /// transitively containing this type to be non-trivial to copy and return the
  /// kind.
  PrimitiveCopyKind isNonTrivialToPrimitiveCopy() const;
 
  /// Check if this is a non-trivial type that would cause a C struct
  /// transitively containing this type to be non-trivial to destructively
  /// move and return the kind. Destructive move in this context is a C++-style
  /// move in which the source object is placed in a valid but unspecified state
  /// after it is moved, as opposed to a truly destructive move in which the
  /// source object is placed in an uninitialized state.
  PrimitiveCopyKind isNonTrivialToPrimitiveDestructiveMove() const;
 
  enum DestructionKind {
    DK_none,
    DK_cxx_destructor,
    DK_objc_strong_lifetime,
    DK_objc_weak_lifetime,
    DK_nontrivial_c_struct
  };
 
  /// Returns a nonzero value if objects of this type require
  /// non-trivial work to clean up after.  Non-zero because it's
  /// conceivable that qualifiers (objc_gc(weak)?) could make
  /// something require destruction.
  DestructionKind isDestructedType() const {
    return isDestructedTypeImpl(*this);
  }
 
  /// Check if this is or contains a C union that is non-trivial to
  /// default-initialize, which is a union that has a member that is non-trivial
  /// to default-initialize. If this returns true,
  /// isNonTrivialToPrimitiveDefaultInitialize returns PDIK_Struct.
  bool hasNonTrivialToPrimitiveDefaultInitializeCUnion() const;
 
  /// Check if this is or contains a C union that is non-trivial to destruct,
  /// which is a union that has a member that is non-trivial to destruct. If
  /// this returns true, isDestructedType returns DK_nontrivial_c_struct.
  bool hasNonTrivialToPrimitiveDestructCUnion() const;
 
  /// Check if this is or contains a C union that is non-trivial to copy, which
  /// is a union that has a member that is non-trivial to copy. If this returns
  /// true, isNonTrivialToPrimitiveCopy returns PCK_Struct.
  bool hasNonTrivialToPrimitiveCopyCUnion() const;
 
  /// Determine whether expressions of the given type are forbidden
  /// from being lvalues in C.
  ///
  /// The expression types that are forbidden to be lvalues are:
  ///   - 'void', but not qualified void
  ///   - function types
  ///
  /// The exact rule here is C99 6.3.2.1:
  ///   An lvalue is an expression with an object type or an incomplete
  ///   type other than void.
  bool isCForbiddenLValueType() const;
 
  /// Substitute type arguments for the Objective-C type parameters used in the
  /// subject type.
  ///
  /// \param ctx ASTContext in which the type exists.
  ///
  /// \param typeArgs The type arguments that will be substituted for the
  /// Objective-C type parameters in the subject type, which are generally
  /// computed via \c Type::getObjCSubstitutions. If empty, the type
  /// parameters will be replaced with their bounds or id/Class, as appropriate
  /// for the context.
  ///
  /// \param context The context in which the subject type was written.
  ///
  /// \returns the resulting type.
  QualType substObjCTypeArgs(ASTContext &ctx,
                             ArrayRef<QualType> typeArgs,
                             ObjCSubstitutionContext context) const;
 
  /// Substitute type arguments from an object type for the Objective-C type
  /// parameters used in the subject type.
  ///
  /// This operation combines the computation of type arguments for
  /// substitution (\c Type::getObjCSubstitutions) with the actual process of
  /// substitution (\c QualType::substObjCTypeArgs) for the convenience of
  /// callers that need to perform a single substitution in isolation.
  ///
  /// \param objectType The type of the object whose member type we're
  /// substituting into. For example, this might be the receiver of a message
  /// or the base of a property access.
  ///
  /// \param dc The declaration context from which the subject type was
  /// retrieved, which indicates (for example) which type parameters should
  /// be substituted.
  ///
  /// \param context The context in which the subject type was written.
  ///
  /// \returns the subject type after replacing all of the Objective-C type
  /// parameters with their corresponding arguments.
  QualType substObjCMemberType(QualType objectType,
                               const DeclContext *dc,
                               ObjCSubstitutionContext context) const;
 
  /// Strip Objective-C "__kindof" types from the given type.
  QualType stripObjCKindOfType(const ASTContext &ctx) const;
 
  /// Remove all qualifiers including _Atomic.
  QualType getAtomicUnqualifiedType() const;
 
private:
  // These methods are implemented in a separate translation unit;
  // "static"-ize them to avoid creating temporary QualTypes in the
  // caller.
  static bool isConstant(QualType T, const ASTContext& Ctx);
  static QualType getDesugaredType(QualType T, const ASTContext &Context);
  static SplitQualType getSplitDesugaredType(QualType T);
  static SplitQualType getSplitUnqualifiedTypeImpl(QualType type);
  static QualType getSingleStepDesugaredTypeImpl(QualType type,
                                                 const ASTContext &C);
  static QualType IgnoreParens(QualType T);
  static DestructionKind isDestructedTypeImpl(QualType type);
 
  /// Check if \param RD is or contains a non-trivial C union.
  static bool hasNonTrivialToPrimitiveDefaultInitializeCUnion(const RecordDecl *RD);
  static bool hasNonTrivialToPrimitiveDestructCUnion(const RecordDecl *RD);
  static bool hasNonTrivialToPrimitiveCopyCUnion(const RecordDecl *RD);
};
 
} // namespace clang
 
namespace llvm {
 
/// Implement simplify_type for QualType, so that we can dyn_cast from QualType
/// to a specific Type class.
template<> struct simplify_type< ::clang::QualType> {
  using SimpleType = const ::clang::Type *;
 
  static SimpleType getSimplifiedValue(::clang::QualType Val) {
    return Val.getTypePtr();
  }
};
 
// Teach SmallPtrSet that QualType is "basically a pointer".
template<>
struct PointerLikeTypeTraits<clang::QualType> {
  static inline void *getAsVoidPointer(clang::QualType P) {
    return P.getAsOpaquePtr();
  }
 
  static inline clang::QualType getFromVoidPointer(void *P) {
    return clang::QualType::getFromOpaquePtr(P);
  }
 
  // Various qualifiers go in low bits.
  static constexpr int NumLowBitsAvailable = 0;
};
 
} // namespace llvm
 
namespace clang {
 
/// Base class that is common to both the \c ExtQuals and \c Type
/// classes, which allows \c QualType to access the common fields between the
/// two.
class ExtQualsTypeCommonBase {
  friend class ExtQuals;
  friend class QualType;
  friend class Type;
 
  /// The "base" type of an extended qualifiers type (\c ExtQuals) or
  /// a self-referential pointer (for \c Type).
  ///
  /// This pointer allows an efficient mapping from a QualType to its
  /// underlying type pointer.
  const Type *const BaseType;
 
  /// The canonical type of this type.  A QualType.
  QualType CanonicalType;
 
  ExtQualsTypeCommonBase(const Type *baseType, QualType canon)
      : BaseType(baseType), CanonicalType(canon) {}
};
 
/// We can encode up to four bits in the low bits of a
/// type pointer, but there are many more type qualifiers that we want
/// to be able to apply to an arbitrary type.  Therefore we have this
/// struct, intended to be heap-allocated and used by QualType to
/// store qualifiers.
///
/// The current design tags the 'const', 'restrict', and 'volatile' qualifiers
/// in three low bits on the QualType pointer; a fourth bit records whether
/// the pointer is an ExtQuals node. The extended qualifiers (address spaces,
/// Objective-C GC attributes) are much more rare.
class ExtQuals : public ExtQualsTypeCommonBase, public llvm::FoldingSetNode {
  // NOTE: changing the fast qualifiers should be straightforward as
  // long as you don't make 'const' non-fast.
  // 1. Qualifiers:
  //    a) Modify the bitmasks (Qualifiers::TQ and DeclSpec::TQ).
  //       Fast qualifiers must occupy the low-order bits.
  //    b) Update Qualifiers::FastWidth and FastMask.
  // 2. QualType:
  //    a) Update is{Volatile,Restrict}Qualified(), defined inline.
  //    b) Update remove{Volatile,Restrict}, defined near the end of
  //       this header.
  // 3. ASTContext:
  //    a) Update get{Volatile,Restrict}Type.
 
  /// The immutable set of qualifiers applied by this node. Always contains
  /// extended qualifiers.
  Qualifiers Quals;
 
  ExtQuals *this_() { return this; }
 
public:
  ExtQuals(const Type *baseType, QualType canon, Qualifiers quals)
      : ExtQualsTypeCommonBase(baseType,
                               canon.isNull() ? QualType(this_(), 0) : canon),
        Quals(quals) {
    assert(Quals.hasNonFastQualifiers()
           && "ExtQuals created with no fast qualifiers");
    assert(!Quals.hasFastQualifiers()
           && "ExtQuals created with fast qualifiers");
  }
 
  Qualifiers getQualifiers() const { return Quals; }
 
  bool hasObjCGCAttr() const { return Quals.hasObjCGCAttr(); }
  Qualifiers::GC getObjCGCAttr() const { return Quals.getObjCGCAttr(); }
 
  bool hasObjCLifetime() const { return Quals.hasObjCLifetime(); }
  Qualifiers::ObjCLifetime getObjCLifetime() const {
    return Quals.getObjCLifetime();
  }
 
  bool hasAddressSpace() const { return Quals.hasAddressSpace(); }
  LangAS getAddressSpace() const { return Quals.getAddressSpace(); }
 
  const Type *getBaseType() const { return BaseType; }
 
public:
  void Profile(llvm::FoldingSetNodeID &ID) const {
    Profile(ID, getBaseType(), Quals);
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID,
                      const Type *BaseType,
                      Qualifiers Quals) {
    assert(!Quals.hasFastQualifiers() && "fast qualifiers in ExtQuals hash!");
    ID.AddPointer(BaseType);
    Quals.Profile(ID);
  }
};
 
/// The kind of C++11 ref-qualifier associated with a function type.
/// This determines whether a member function's "this" object can be an
/// lvalue, rvalue, or neither.
enum RefQualifierKind {
  /// No ref-qualifier was provided.
  RQ_None = 0,
 
  /// An lvalue ref-qualifier was provided (\c &).
  RQ_LValue,
 
  /// An rvalue ref-qualifier was provided (\c &&).
  RQ_RValue
};
 
/// Which keyword(s) were used to create an AutoType.
enum class AutoTypeKeyword {
  /// auto
  Auto,
 
  /// decltype(auto)
  DecltypeAuto,
 
  /// __auto_type (GNU extension)
  GNUAutoType
};
 
/// The base class of the type hierarchy.
///
/// A central concept with types is that each type always has a canonical
/// type.  A canonical type is the type with any typedef names stripped out
/// of it or the types it references.  For example, consider:
///
///  typedef int  foo;
///  typedef foo* bar;
///    'int *'    'foo *'    'bar'
///
/// There will be a Type object created for 'int'.  Since int is canonical, its
/// CanonicalType pointer points to itself.  There is also a Type for 'foo' (a
/// TypedefType).  Its CanonicalType pointer points to the 'int' Type.  Next
/// there is a PointerType that represents 'int*', which, like 'int', is
/// canonical.  Finally, there is a PointerType type for 'foo*' whose canonical
/// type is 'int*', and there is a TypedefType for 'bar', whose canonical type
/// is also 'int*'.
///
/// Non-canonical types are useful for emitting diagnostics, without losing
/// information about typedefs being used.  Canonical types are useful for type
/// comparisons (they allow by-pointer equality tests) and useful for reasoning
/// about whether something has a particular form (e.g. is a function type),
/// because they implicitly, recursively, strip all typedefs out of a type.
///
/// Types, once created, are immutable.
///
class alignas(8) Type : public ExtQualsTypeCommonBase {
public:
  enum TypeClass {
#define TYPE(Class, Base) Class,
#define LAST_TYPE(Class) TypeLast = Class
#define ABSTRACT_TYPE(Class, Base)
#include "clang/AST/TypeNodes.inc"
  };
 
private:
  /// Bitfields required by the Type class.
  class TypeBitfields {
    friend class Type;
    template <class T> friend class TypePropertyCache;
 
    /// TypeClass bitfield - Enum that specifies what subclass this belongs to.
    unsigned TC : 8;
 
    /// Store information on the type dependency.
    unsigned Dependence : llvm::BitWidth<TypeDependence>;
 
    /// True if the cache (i.e. the bitfields here starting with
    /// 'Cache') is valid.
    mutable unsigned CacheValid : 1;
 
    /// Linkage of this type.
    mutable unsigned CachedLinkage : 3;
 
    /// Whether this type involves and local or unnamed types.
    mutable unsigned CachedLocalOrUnnamed : 1;
 
    /// Whether this type comes from an AST file.
    mutable unsigned FromAST : 1;
 
    bool isCacheValid() const {
      return CacheValid;
    }
 
    Linkage getLinkage() const {
      assert(isCacheValid() && "getting linkage from invalid cache");
      return static_cast<Linkage>(CachedLinkage);
    }
 
    bool hasLocalOrUnnamedType() const {
      assert(isCacheValid() && "getting linkage from invalid cache");
      return CachedLocalOrUnnamed;
    }
  };
  enum { NumTypeBits = 8 + llvm::BitWidth<TypeDependence> + 6 };
 
protected:
  // These classes allow subclasses to somewhat cleanly pack bitfields
  // into Type.
 
  class ArrayTypeBitfields {
    friend class ArrayType;
 
    unsigned : NumTypeBits;
 
    /// CVR qualifiers from declarations like
    /// 'int X[static restrict 4]'. For function parameters only.
    unsigned IndexTypeQuals : 3;
 
    /// Storage class qualifiers from declarations like
    /// 'int X[static restrict 4]'. For function parameters only.
    /// Actually an ArrayType::ArraySizeModifier.
    unsigned SizeModifier : 3;
  };
 
  class ConstantArrayTypeBitfields {
    friend class ConstantArrayType;
 
    unsigned : NumTypeBits + 3 + 3;
 
    /// Whether we have a stored size expression.
    unsigned HasStoredSizeExpr : 1;
  };
 
  class BuiltinTypeBitfields {
    friend class BuiltinType;
 
    unsigned : NumTypeBits;
 
    /// The kind (BuiltinType::Kind) of builtin type this is.
    unsigned Kind : 8;
  };
 
  /// FunctionTypeBitfields store various bits belonging to FunctionProtoType.
  /// Only common bits are stored here. Additional uncommon bits are stored
  /// in a trailing object after FunctionProtoType.
  class FunctionTypeBitfields {
    friend class FunctionProtoType;
    friend class FunctionType;
 
    unsigned : NumTypeBits;
 
    /// Extra information which affects how the function is called, like
    /// regparm and the calling convention.
    unsigned ExtInfo : 13;
 
    /// The ref-qualifier associated with a \c FunctionProtoType.
    ///
    /// This is a value of type \c RefQualifierKind.
    unsigned RefQualifier : 2;
 
    /// Used only by FunctionProtoType, put here to pack with the
    /// other bitfields.
    /// The qualifiers are part of FunctionProtoType because...
    ///
    /// C++ 8.3.5p4: The return type, the parameter type list and the
    /// cv-qualifier-seq, [...], are part of the function type.
    unsigned FastTypeQuals : Qualifiers::FastWidth;
    /// Whether this function has extended Qualifiers.
    unsigned HasExtQuals : 1;
 
    /// The number of parameters this function has, not counting '...'.
    /// According to [implimits] 8 bits should be enough here but this is
    /// somewhat easy to exceed with metaprogramming and so we would like to
    /// keep NumParams as wide as reasonably possible.
    unsigned NumParams : 16;
 
    /// The type of exception specification this function has.
    unsigned ExceptionSpecType : 4;
 
    /// Whether this function has extended parameter information.
    unsigned HasExtParameterInfos : 1;
 
    /// Whether the function is variadic.
    unsigned Variadic : 1;
 
    /// Whether this function has a trailing return type.
    unsigned HasTrailingReturn : 1;
  };
 
  class ObjCObjectTypeBitfields {
    friend class ObjCObjectType;
 
    unsigned : NumTypeBits;
 
    /// The number of type arguments stored directly on this object type.
    unsigned NumTypeArgs : 7;
 
    /// The number of protocols stored directly on this object type.
    unsigned NumProtocols : 6;
 
    /// Whether this is a "kindof" type.
    unsigned IsKindOf : 1;
  };
 
  class ReferenceTypeBitfields {
    friend class ReferenceType;
 
    unsigned : NumTypeBits;
 
    /// True if the type was originally spelled with an lvalue sigil.
    /// This is never true of rvalue references but can also be false
    /// on lvalue references because of C++0x [dcl.typedef]p9,
    /// as follows:
    ///
    ///   typedef int &ref;    // lvalue, spelled lvalue
    ///   typedef int &&rvref; // rvalue
    ///   ref &a;              // lvalue, inner ref, spelled lvalue
    ///   ref &&a;             // lvalue, inner ref
    ///   rvref &a;            // lvalue, inner ref, spelled lvalue
    ///   rvref &&a;           // rvalue, inner ref
    unsigned SpelledAsLValue : 1;
 
    /// True if the inner type is a reference type.  This only happens
    /// in non-canonical forms.
    unsigned InnerRef : 1;
  };
 
  class TypeWithKeywordBitfields {
    friend class TypeWithKeyword;
 
    unsigned : NumTypeBits;
 
    /// An ElaboratedTypeKeyword.  8 bits for efficient access.
    unsigned Keyword : 8;
  };
 
  enum { NumTypeWithKeywordBits = 8 };
 
  class ElaboratedTypeBitfields {
    friend class ElaboratedType;
 
    unsigned : NumTypeBits;
    unsigned : NumTypeWithKeywordBits;
 
    /// Whether the ElaboratedType has a trailing OwnedTagDecl.
    unsigned HasOwnedTagDecl : 1;
  };
 
  class VectorTypeBitfields {
    friend class VectorType;
    friend class DependentVectorType;
 
    unsigned : NumTypeBits;
 
    /// The kind of vector, either a generic vector type or some
    /// target-specific vector type such as for AltiVec or Neon.
    unsigned VecKind : 3;
    /// The number of elements in the vector.
    uint32_t NumElements;
  };
 
  class AttributedTypeBitfields {
    friend class AttributedType;
 
    unsigned : NumTypeBits;
 
    /// An AttributedType::Kind
    unsigned AttrKind : 32 - NumTypeBits;
  };
 
  class AutoTypeBitfields {
    friend class AutoType;
 
    unsigned : NumTypeBits;
 
    /// Was this placeholder type spelled as 'auto', 'decltype(auto)',
    /// or '__auto_type'?  AutoTypeKeyword value.
    unsigned Keyword : 2;
 
    /// The number of template arguments in the type-constraints, which is
    /// expected to be able to hold at least 1024 according to [implimits].
    /// However as this limit is somewhat easy to hit with template
    /// metaprogramming we'd prefer to keep it as large as possible.
    /// At the moment it has been left as a non-bitfield since this type
    /// safely fits in 64 bits as an unsigned, so there is no reason to
    /// introduce the performance impact of a bitfield.
    unsigned NumArgs;
  };
 
  class SubstTemplateTypeParmPackTypeBitfields {
    friend class SubstTemplateTypeParmPackType;
 
    unsigned : NumTypeBits;
 
    /// The number of template arguments in \c Arguments, which is
    /// expected to be able to hold at least 1024 according to [implimits].
    /// However as this limit is somewhat easy to hit with template
    /// metaprogramming we'd prefer to keep it as large as possible.
    /// At the moment it has been left as a non-bitfield since this type
    /// safely fits in 64 bits as an unsigned, so there is no reason to
    /// introduce the performance impact of a bitfield.
    unsigned NumArgs;
  };
 
  class TemplateSpecializationTypeBitfields {
    friend class TemplateSpecializationType;
 
    unsigned : NumTypeBits;
 
    /// Whether this template specialization type is a substituted type alias.
    unsigned TypeAlias : 1;
 
    /// The number of template arguments named in this class template
    /// specialization, which is expected to be able to hold at least 1024
    /// according to [implimits]. However, as this limit is somewhat easy to
    /// hit with template metaprogramming we'd prefer to keep it as large
    /// as possible. At the moment it has been left as a non-bitfield since
    /// this type safely fits in 64 bits as an unsigned, so there is no reason
    /// to introduce the performance impact of a bitfield.
    unsigned NumArgs;
  };
 
  class DependentTemplateSpecializationTypeBitfields {
    friend class DependentTemplateSpecializationType;
 
    unsigned : NumTypeBits;
    unsigned : NumTypeWithKeywordBits;
 
    /// The number of template arguments named in this class template
    /// specialization, which is expected to be able to hold at least 1024
    /// according to [implimits]. However, as this limit is somewhat easy to
    /// hit with template metaprogramming we'd prefer to keep it as large
    /// as possible. At the moment it has been left as a non-bitfield since
    /// this type safely fits in 64 bits as an unsigned, so there is no reason
    /// to introduce the performance impact of a bitfield.
    unsigned NumArgs;
  };
 
  class PackExpansionTypeBitfields {
    friend class PackExpansionType;
 
    unsigned : NumTypeBits;
 
    /// The number of expansions that this pack expansion will
    /// generate when substituted (+1), which is expected to be able to
    /// hold at least 1024 according to [implimits]. However, as this limit
    /// is somewhat easy to hit with template metaprogramming we'd prefer to
    /// keep it as large as possible. At the moment it has been left as a
    /// non-bitfield since this type safely fits in 64 bits as an unsigned, so
    /// there is no reason to introduce the performance impact of a bitfield.
    ///
    /// This field will only have a non-zero value when some of the parameter
    /// packs that occur within the pattern have been substituted but others
    /// have not.
    unsigned NumExpansions;
  };
 
  union {
    TypeBitfields TypeBits;
    ArrayTypeBitfields ArrayTypeBits;
    ConstantArrayTypeBitfields ConstantArrayTypeBits;
    AttributedTypeBitfields AttributedTypeBits;
    AutoTypeBitfields AutoTypeBits;
    BuiltinTypeBitfields BuiltinTypeBits;
    FunctionTypeBitfields FunctionTypeBits;
    ObjCObjectTypeBitfields ObjCObjectTypeBits;
    ReferenceTypeBitfields ReferenceTypeBits;
    TypeWithKeywordBitfields TypeWithKeywordBits;
    ElaboratedTypeBitfields ElaboratedTypeBits;
    VectorTypeBitfields VectorTypeBits;
    SubstTemplateTypeParmPackTypeBitfields SubstTemplateTypeParmPackTypeBits;
    TemplateSpecializationTypeBitfields TemplateSpecializationTypeBits;
    DependentTemplateSpecializationTypeBitfields
      DependentTemplateSpecializationTypeBits;
    PackExpansionTypeBitfields PackExpansionTypeBits;
  };
 
private:
  template <class T> friend class TypePropertyCache;
 
  /// Set whether this type comes from an AST file.
  void setFromAST(bool V = true) const {
    TypeBits.FromAST = V;
  }
 
protected:
  friend class ASTContext;
 
  Type(TypeClass tc, QualType canon, TypeDependence Dependence)
      : ExtQualsTypeCommonBase(this,
                               canon.isNull() ? QualType(this_(), 0) : canon) {
    static_assert(sizeof(*this) <= 8 + sizeof(ExtQualsTypeCommonBase),
                  "changing bitfields changed sizeof(Type)!");
    static_assert(alignof(decltype(*this)) % sizeof(void *) == 0,
                  "Insufficient alignment!");
    TypeBits.TC = tc;
    TypeBits.Dependence = static_cast<unsigned>(Dependence);
    TypeBits.CacheValid = false;
    TypeBits.CachedLocalOrUnnamed = false;
    TypeBits.CachedLinkage = NoLinkage;
    TypeBits.FromAST = false;
  }
 
  // silence VC++ warning C4355: 'this' : used in base member initializer list
  Type *this_() { return this; }
 
  void setDependence(TypeDependence D) {
    TypeBits.Dependence = static_cast<unsigned>(D);
  }
 
  void addDependence(TypeDependence D) { setDependence(getDependence() | D); }
 
public:
  friend class ASTReader;
  friend class ASTWriter;
  template <class T> friend class serialization::AbstractTypeReader;
  template <class T> friend class serialization::AbstractTypeWriter;
 
  Type(const Type &) = delete;
  Type(Type &&) = delete;
  Type &operator=(const Type &) = delete;
  Type &operator=(Type &&) = delete;
 
  TypeClass getTypeClass() const { return static_cast<TypeClass>(TypeBits.TC); }
 
  /// Whether this type comes from an AST file.
  bool isFromAST() const { return TypeBits.FromAST; }
 
  /// Whether this type is or contains an unexpanded parameter
  /// pack, used to support C++0x variadic templates.
  ///
  /// A type that contains a parameter pack shall be expanded by the
  /// ellipsis operator at some point. For example, the typedef in the
  /// following example contains an unexpanded parameter pack 'T':
  ///
  /// \code
  /// template<typename ...T>
  /// struct X {
  ///   typedef T* pointer_types; // ill-formed; T is a parameter pack.
  /// };
  /// \endcode
  ///
  /// Note that this routine does not specify which
  bool containsUnexpandedParameterPack() const {
    return getDependence() & TypeDependence::UnexpandedPack;
  }
 
  /// Determines if this type would be canonical if it had no further
  /// qualification.
  bool isCanonicalUnqualified() const {
    return CanonicalType == QualType(this, 0);
  }
 
  /// Pull a single level of sugar off of this locally-unqualified type.
  /// Users should generally prefer SplitQualType::getSingleStepDesugaredType()
  /// or QualType::getSingleStepDesugaredType(const ASTContext&).
  QualType getLocallyUnqualifiedSingleStepDesugaredType() const;
 
  /// As an extension, we classify types as one of "sized" or "sizeless";
  /// every type is one or the other.  Standard types are all sized;
  /// sizeless types are purely an extension.
  ///
  /// Sizeless types contain data with no specified size, alignment,
  /// or layout.
  bool isSizelessType() const;
  bool isSizelessBuiltinType() const;
 
  /// Determines if this is a sizeless type supported by the
  /// 'arm_sve_vector_bits' type attribute, which can be applied to a single
  /// SVE vector or predicate, excluding tuple types such as svint32x4_t.
  bool isVLSTBuiltinType() const;
 
  /// Returns the representative type for the element of an SVE builtin type.
  /// This is used to represent fixed-length SVE vectors created with the
  /// 'arm_sve_vector_bits' type attribute as VectorType.
  QualType getSveEltType(const ASTContext &Ctx) const;
 
  /// Types are partitioned into 3 broad categories (C99 6.2.5p1):
  /// object types, function types, and incomplete types.
 
  /// Return true if this is an incomplete type.
  /// A type that can describe objects, but which lacks information needed to
  /// determine its size (e.g. void, or a fwd declared struct). Clients of this
  /// routine will need to determine if the size is actually required.
  ///
  /// Def If non-null, and the type refers to some kind of declaration
  /// that can be completed (such as a C struct, C++ class, or Objective-C
  /// class), will be set to the declaration.
  bool isIncompleteType(NamedDecl **Def = nullptr) const;
 
  /// Return true if this is an incomplete or object
  /// type, in other words, not a function type.
  bool isIncompleteOrObjectType() const {
    return !isFunctionType();
  }
 
  /// Determine whether this type is an object type.
  bool isObjectType() const {
    // C++ [basic.types]p8:
    //   An object type is a (possibly cv-qualified) type that is not a
    //   function type, not a reference type, and not a void type.
    return !isReferenceType() && !isFunctionType() && !isVoidType();
  }
 
  /// Return true if this is a literal type
  /// (C++11 [basic.types]p10)
  bool isLiteralType(const ASTContext &Ctx) const;
 
  /// Determine if this type is a structural type, per C++20 [temp.param]p7.
  bool isStructuralType() const;
 
  /// Test if this type is a standard-layout type.
  /// (C++0x [basic.type]p9)
  bool isStandardLayoutType() const;
 
  /// Helper methods to distinguish type categories. All type predicates
  /// operate on the canonical type, ignoring typedefs and qualifiers.
 
  /// Returns true if the type is a builtin type.
  bool isBuiltinType() const;
 
  /// Test for a particular builtin type.
  bool isSpecificBuiltinType(unsigned K) const;
 
  /// Test for a type which does not represent an actual type-system type but
  /// is instead used as a placeholder for various convenient purposes within
  /// Clang.  All such types are BuiltinTypes.
  bool isPlaceholderType() const;
  const BuiltinType *getAsPlaceholderType() const;
 
  /// Test for a specific placeholder type.
  bool isSpecificPlaceholderType(unsigned K) const;
 
  /// Test for a placeholder type other than Overload; see
  /// BuiltinType::isNonOverloadPlaceholderType.
  bool isNonOverloadPlaceholderType() const;
 
  /// isIntegerType() does *not* include complex integers (a GCC extension).
  /// isComplexIntegerType() can be used to test for complex integers.
  bool isIntegerType() const;     // C99 6.2.5p17 (int, char, bool, enum)
  bool isEnumeralType() const;
 
  /// Determine whether this type is a scoped enumeration type.
  bool isScopedEnumeralType() const;
  bool isBooleanType() const;
  bool isCharType() const;
  bool isWideCharType() const;
  bool isChar8Type() const;
  bool isChar16Type() const;
  bool isChar32Type() const;
  bool isAnyCharacterType() const;
  bool isIntegralType(const ASTContext &Ctx) const;
 
  /// Determine whether this type is an integral or enumeration type.
  bool isIntegralOrEnumerationType() const;
 
  /// Determine whether this type is an integral or unscoped enumeration type.
  bool isIntegralOrUnscopedEnumerationType() const;
  bool isUnscopedEnumerationType() const;
 
  /// Floating point categories.
  bool isRealFloatingType() const; // C99 6.2.5p10 (float, double, long double)
  /// isComplexType() does *not* include complex integers (a GCC extension).
  /// isComplexIntegerType() can be used to test for complex integers.
  bool isComplexType() const;      // C99 6.2.5p11 (complex)
  bool isAnyComplexType() const;   // C99 6.2.5p11 (complex) + Complex Int.
  bool isFloatingType() const;     // C99 6.2.5p11 (real floating + complex)
  bool isHalfType() const;         // OpenCL 6.1.1.1, NEON (IEEE 754-2008 half)
  bool isFloat16Type() const;      // C11 extension ISO/IEC TS 18661
  bool isBFloat16Type() const;
  bool isFloat128Type() const;
  bool isIbm128Type() const;
  bool isRealType() const;         // C99 6.2.5p17 (real floating + integer)
  bool isArithmeticType() const;   // C99 6.2.5p18 (integer + floating)
  bool isVoidType() const;         // C99 6.2.5p19
  bool isScalarType() const;       // C99 6.2.5p21 (arithmetic + pointers)
  bool isAggregateType() const;
  bool isFundamentalType() const;
  bool isCompoundType() const;
 
  // Type Predicates: Check to see if this type is structurally the specified
  // type, ignoring typedefs and qualifiers.
  bool isFunctionType() const;
  bool isFunctionNoProtoType() const { return getAs<FunctionNoProtoType>(); }
  bool isFunctionProtoType() const { return getAs<FunctionProtoType>(); }
  bool isPointerType() const;
  bool isAnyPointerType() const;   // Any C pointer or ObjC object pointer
  bool isBlockPointerType() const;
  bool isVoidPointerType() const;
  bool isReferenceType() const;
  bool isLValueReferenceType() const;
  bool isRValueReferenceType() const;
  bool isObjectPointerType() const;
  bool isFunctionPointerType() const;
  bool isFunctionReferenceType() const;
  bool isMemberPointerType() const;
  bool isMemberFunctionPointerType() const;
  bool isMemberDataPointerType() const;
  bool isArrayType() const;
  bool isConstantArrayType() const;
  bool isIncompleteArrayType() const;
  bool isVariableArrayType() const;
  bool isDependentSizedArrayType() const;
  bool isRecordType() const;
  bool isClassType() const;
  bool isStructureType() const;
  bool isObjCBoxableRecordType() const;
  bool isInterfaceType() const;
  bool isStructureOrClassType() const;
  bool isUnionType() const;
  bool isComplexIntegerType() const;            // GCC _Complex integer type.
  bool isVectorType() const;                    // GCC vector type.
  bool isExtVectorType() const;                 // Extended vector type.
  bool isMatrixType() const;                    // Matrix type.
  bool isConstantMatrixType() const;            // Constant matrix type.
  bool isDependentAddressSpaceType() const;     // value-dependent address space qualifier
  bool isObjCObjectPointerType() const;         // pointer to ObjC object
  bool isObjCRetainableType() const;            // ObjC object or block pointer
  bool isObjCLifetimeType() const;              // (array of)* retainable type
  bool isObjCIndirectLifetimeType() const;      // (pointer to)* lifetime type
  bool isObjCNSObjectType() const;              // __attribute__((NSObject))
  bool isObjCIndependentClassType() const;      // __attribute__((objc_independent_class))
  // FIXME: change this to 'raw' interface type, so we can used 'interface' type
  // for the common case.
  bool isObjCObjectType() const;                // NSString or typeof(*(id)0)
  bool isObjCQualifiedInterfaceType() const;    // NSString<foo>
  bool isObjCQualifiedIdType() const;           // id<foo>
  bool isObjCQualifiedClassType() const;        // Class<foo>
  bool isObjCObjectOrInterfaceType() const;
  bool isObjCIdType() const;                    // id
  bool isDecltypeType() const;
  /// Was this type written with the special inert-in-ARC __unsafe_unretained
  /// qualifier?
  ///
  /// This approximates the answer to the following question: if this
  /// translation unit were compiled in ARC, would this type be qualified
  /// with __unsafe_unretained?
  bool isObjCInertUnsafeUnretainedType() const {
    return hasAttr(attr::ObjCInertUnsafeUnretained);
  }
 
  /// Whether the type is Objective-C 'id' or a __kindof type of an
  /// object type, e.g., __kindof NSView * or __kindof id
  /// <NSCopying>.
  ///
  /// \param bound Will be set to the bound on non-id subtype types,
  /// which will be (possibly specialized) Objective-C class type, or
  /// null for 'id.
  bool isObjCIdOrObjectKindOfType(const ASTContext &ctx,
                                  const ObjCObjectType *&bound) const;
 
  bool isObjCClassType() const;                 // Class
 
  /// Whether the type is Objective-C 'Class' or a __kindof type of an
  /// Class type, e.g., __kindof Class <NSCopying>.
  ///
  /// Unlike \c isObjCIdOrObjectKindOfType, there is no relevant bound
  /// here because Objective-C's type system cannot express "a class
  /// object for a subclass of NSFoo".
  bool isObjCClassOrClassKindOfType() const;
 
  bool isBlockCompatibleObjCPointerType(ASTContext &ctx) const;
  bool isObjCSelType() const;                 // Class
  bool isObjCBuiltinType() const;               // 'id' or 'Class'
  bool isObjCARCBridgableType() const;
  bool isCARCBridgableType() const;
  bool isTemplateTypeParmType() const;          // C++ template type parameter
  bool isNullPtrType() const;                   // C++11 std::nullptr_t
  bool isNothrowT() const;                      // C++   std::nothrow_t
  bool isAlignValT() const;                     // C++17 std::align_val_t
  bool isStdByteType() const;                   // C++17 std::byte
  bool isAtomicType() const;                    // C11 _Atomic()
  bool isUndeducedAutoType() const;             // C++11 auto or
                                                // C++14 decltype(auto)
  bool isTypedefNameType() const;               // typedef or alias template
 
#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
  bool is##Id##Type() const;
#include "clang/Basic/OpenCLImageTypes.def"
 
  bool isImageType() const;                     // Any OpenCL image type
 
  bool isSamplerT() const;                      // OpenCL sampler_t
  bool isEventT() const;                        // OpenCL event_t
  bool isClkEventT() const;                     // OpenCL clk_event_t
  bool isQueueT() const;                        // OpenCL queue_t
  bool isReserveIDT() const;                    // OpenCL reserve_id_t
 
#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
  bool is##Id##Type() const;
#include "clang/Basic/OpenCLExtensionTypes.def"
  // Type defined in cl_intel_device_side_avc_motion_estimation OpenCL extension
  bool isOCLIntelSubgroupAVCType() const;
  bool isOCLExtOpaqueType() const;              // Any OpenCL extension type
 
  bool isPipeType() const;                      // OpenCL pipe type
  bool isBitIntType() const;                    // Bit-precise integer type
  bool isOpenCLSpecificType() const;            // Any OpenCL specific type
 
  /// Determines if this type, which must satisfy
  /// isObjCLifetimeType(), is implicitly __unsafe_unretained rather
  /// than implicitly __strong.
  bool isObjCARCImplicitlyUnretainedType() const;
 
  /// Check if the type is the CUDA device builtin surface type.
  bool isCUDADeviceBuiltinSurfaceType() const;
  /// Check if the type is the CUDA device builtin texture type.
  bool isCUDADeviceBuiltinTextureType() const;
 
  /// Return the implicit lifetime for this type, which must not be dependent.
  Qualifiers::ObjCLifetime getObjCARCImplicitLifetime() const;
 
  enum ScalarTypeKind {
    STK_CPointer,
    STK_BlockPointer,
    STK_ObjCObjectPointer,
    STK_MemberPointer,
    STK_Bool,
    STK_Integral,
    STK_Floating,
    STK_IntegralComplex,
    STK_FloatingComplex,
    STK_FixedPoint
  };
 
  /// Given that this is a scalar type, classify it.
  ScalarTypeKind getScalarTypeKind() const;
 
  TypeDependence getDependence() const {
    return static_cast<TypeDependence>(TypeBits.Dependence);
  }
 
  /// Whether this type is an error type.
  bool containsErrors() const {
    return getDependence() & TypeDependence::Error;
  }
 
  /// Whether this type is a dependent type, meaning that its definition
  /// somehow depends on a template parameter (C++ [temp.dep.type]).
  bool isDependentType() const {
    return getDependence() & TypeDependence::Dependent;
  }
 
  /// Determine whether this type is an instantiation-dependent type,
  /// meaning that the type involves a template parameter (even if the
  /// definition does not actually depend on the type substituted for that
  /// template parameter).
  bool isInstantiationDependentType() const {
    return getDependence() & TypeDependence::Instantiation;
  }
 
  /// Determine whether this type is an undeduced type, meaning that
  /// it somehow involves a C++11 'auto' type or similar which has not yet been
  /// deduced.
  bool isUndeducedType() const;
 
  /// Whether this type is a variably-modified type (C99 6.7.5).
  bool isVariablyModifiedType() const {
    return getDependence() & TypeDependence::VariablyModified;
  }
 
  /// Whether this type involves a variable-length array type
  /// with a definite size.
  bool hasSizedVLAType() const;
 
  /// Whether this type is or contains a local or unnamed type.
  bool hasUnnamedOrLocalType() const;
 
  bool isOverloadableType() const;
 
  /// Determine wither this type is a C++ elaborated-type-specifier.
  bool isElaboratedTypeSpecifier() const;
 
  bool canDecayToPointerType() const;
 
  /// Whether this type is represented natively as a pointer.  This includes
  /// pointers, references, block pointers, and Objective-C interface,
  /// qualified id, and qualified interface types, as well as nullptr_t.
  bool hasPointerRepresentation() const;
 
  /// Whether this type can represent an objective pointer type for the
  /// purpose of GC'ability
  bool hasObjCPointerRepresentation() const;
 
  /// Determine whether this type has an integer representation
  /// of some sort, e.g., it is an integer type or a vector.
  bool hasIntegerRepresentation() const;
 
  /// Determine whether this type has an signed integer representation
  /// of some sort, e.g., it is an signed integer type or a vector.
  bool hasSignedIntegerRepresentation() const;
 
  /// Determine whether this type has an unsigned integer representation
  /// of some sort, e.g., it is an unsigned integer type or a vector.
  bool hasUnsignedIntegerRepresentation() const;
 
  /// Determine whether this type has a floating-point representation
  /// of some sort, e.g., it is a floating-point type or a vector thereof.
  bool hasFloatingRepresentation() const;
 
  // Type Checking Functions: Check to see if this type is structurally the
  // specified type, ignoring typedefs and qualifiers, and return a pointer to
  // the best type we can.
  const RecordType *getAsStructureType() const;
  /// NOTE: getAs*ArrayType are methods on ASTContext.
  const RecordType *getAsUnionType() const;
  const ComplexType *getAsComplexIntegerType() const; // GCC complex int type.
  const ObjCObjectType *getAsObjCInterfaceType() const;
 
  // The following is a convenience method that returns an ObjCObjectPointerType
  // for object declared using an interface.
  const ObjCObjectPointerType *getAsObjCInterfacePointerType() const;
  const ObjCObjectPointerType *getAsObjCQualifiedIdType() const;
  const ObjCObjectPointerType *getAsObjCQualifiedClassType() const;
  const ObjCObjectType *getAsObjCQualifiedInterfaceType() const;
 
  /// Retrieves the CXXRecordDecl that this type refers to, either
  /// because the type is a RecordType or because it is the injected-class-name
  /// type of a class template or class template partial specialization.
  CXXRecordDecl *getAsCXXRecordDecl() const;
 
  /// Retrieves the RecordDecl this type refers to.
  RecordDecl *getAsRecordDecl() const;
 
  /// Retrieves the TagDecl that this type refers to, either
  /// because the type is a TagType or because it is the injected-class-name
  /// type of a class template or class template partial specialization.
  TagDecl *getAsTagDecl() const;
 
  /// If this is a pointer or reference to a RecordType, return the
  /// CXXRecordDecl that the type refers to.
  ///
  /// If this is not a pointer or reference, or the type being pointed to does
  /// not refer to a CXXRecordDecl, returns NULL.
  const CXXRecordDecl *getPointeeCXXRecordDecl() const;
 
  /// Get the DeducedType whose type will be deduced for a variable with
  /// an initializer of this type. This looks through declarators like pointer
  /// types, but not through decltype or typedefs.
  DeducedType *getContainedDeducedType() const;
 
  /// Get the AutoType whose type will be deduced for a variable with
  /// an initializer of this type. This looks through declarators like pointer
  /// types, but not through decltype or typedefs.
  AutoType *getContainedAutoType() const {
    return dyn_cast_or_null<AutoType>(getContainedDeducedType());
  }
 
  /// Determine whether this type was written with a leading 'auto'
  /// corresponding to a trailing return type (possibly for a nested
  /// function type within a pointer to function type or similar).
  bool hasAutoForTrailingReturnType() const;
 
  /// Member-template getAs<specific type>'.  Look through sugar for
  /// an instance of <specific type>.   This scheme will eventually
  /// replace the specific getAsXXXX methods above.
  ///
  /// There are some specializations of this member template listed
  /// immediately following this class.
  template <typename T> const T *getAs() const;
 
  /// Member-template getAsAdjusted<specific type>. Look through specific kinds
  /// of sugar (parens, attributes, etc) for an instance of <specific type>.
  /// This is used when you need to walk over sugar nodes that represent some
  /// kind of type adjustment from a type that was written as a <specific type>
  /// to another type that is still canonically a <specific type>.
  template <typename T> const T *getAsAdjusted() const;
 
  /// A variant of getAs<> for array types which silently discards
  /// qualifiers from the outermost type.
  const ArrayType *getAsArrayTypeUnsafe() const;
 
  /// Member-template castAs<specific type>.  Look through sugar for
  /// the underlying instance of <specific type>.
  ///
  /// This method has the same relationship to getAs<T> as cast<T> has
  /// to dyn_cast<T>; which is to say, the underlying type *must*
  /// have the intended type, and this method will never return null.
  template <typename T> const T *castAs() const;
 
  /// A variant of castAs<> for array type which silently discards
  /// qualifiers from the outermost type.
  const ArrayType *castAsArrayTypeUnsafe() const;
 
  /// Determine whether this type had the specified attribute applied to it
  /// (looking through top-level type sugar).
  bool hasAttr(attr::Kind AK) const;
 
  /// Get the base element type of this type, potentially discarding type
  /// qualifiers.  This should never be used when type qualifiers
  /// are meaningful.
  const Type *getBaseElementTypeUnsafe() const;
 
  /// If this is an array type, return the element type of the array,
  /// potentially with type qualifiers missing.
  /// This should never be used when type qualifiers are meaningful.
  const Type *getArrayElementTypeNoTypeQual() const;
 
  /// If this is a pointer type, return the pointee type.
  /// If this is an array type, return the array element type.
  /// This should never be used when type qualifiers are meaningful.
  const Type *getPointeeOrArrayElementType() const;
 
  /// If this is a pointer, ObjC object pointer, or block
  /// pointer, this returns the respective pointee.
  QualType getPointeeType() const;
 
  /// Return the specified type with any "sugar" removed from the type,
  /// removing any typedefs, typeofs, etc., as well as any qualifiers.
  const Type *getUnqualifiedDesugaredType() const;
 
  /// More type predicates useful for type checking/promotion
  bool isPromotableIntegerType() const; // C99 6.3.1.1p2
 
  /// Return true if this is an integer type that is
  /// signed, according to C99 6.2.5p4 [char, signed char, short, int, long..],
  /// or an enum decl which has a signed representation.
  bool isSignedIntegerType() const;
 
  /// Return true if this is an integer type that is
  /// unsigned, according to C99 6.2.5p6 [which returns true for _Bool],
  /// or an enum decl which has an unsigned representation.
  bool isUnsignedIntegerType() const;
 
  /// Determines whether this is an integer type that is signed or an
  /// enumeration types whose underlying type is a signed integer type.
  bool isSignedIntegerOrEnumerationType() const;
 
  /// Determines whether this is an integer type that is unsigned or an
  /// enumeration types whose underlying type is a unsigned integer type.
  bool isUnsignedIntegerOrEnumerationType() const;
 
  /// Return true if this is a fixed point type according to
  /// ISO/IEC JTC1 SC22 WG14 N1169.
  bool isFixedPointType() const;
 
  /// Return true if this is a fixed point or integer type.
  bool isFixedPointOrIntegerType() const;
 
  /// Return true if this is a saturated fixed point type according to
  /// ISO/IEC JTC1 SC22 WG14 N1169. This type can be signed or unsigned.
  bool isSaturatedFixedPointType() const;
 
  /// Return true if this is a saturated fixed point type according to
  /// ISO/IEC JTC1 SC22 WG14 N1169. This type can be signed or unsigned.
  bool isUnsaturatedFixedPointType() const;
 
  /// Return true if this is a fixed point type that is signed according
  /// to ISO/IEC JTC1 SC22 WG14 N1169. This type can also be saturated.
  bool isSignedFixedPointType() const;
 
  /// Return true if this is a fixed point type that is unsigned according
  /// to ISO/IEC JTC1 SC22 WG14 N1169. This type can also be saturated.
  bool isUnsignedFixedPointType() const;
 
  /// Return true if this is not a variable sized type,
  /// according to the rules of C99 6.7.5p3.  It is not legal to call this on
  /// incomplete types.
  bool isConstantSizeType() const;
 
  /// Returns true if this type can be represented by some
  /// set of type specifiers.
  bool isSpecifierType() const;
 
  /// Determine the linkage of this type.
  Linkage getLinkage() const;
 
  /// Determine the visibility of this type.
  Visibility getVisibility() const {
    return getLinkageAndVisibility().getVisibility();
  }
 
  /// Return true if the visibility was explicitly set is the code.
  bool isVisibilityExplicit() const {
    return getLinkageAndVisibility().isVisibilityExplicit();
  }
 
  /// Determine the linkage and visibility of this type.
  LinkageInfo getLinkageAndVisibility() const;
 
  /// True if the computed linkage is valid. Used for consistency
  /// checking. Should always return true.
  bool isLinkageValid() const;
 
  /// Determine the nullability of the given type.
  ///
  /// Note that nullability is only captured as sugar within the type
  /// system, not as part of the canonical type, so nullability will
  /// be lost by canonicalization and desugaring.
  Optional<NullabilityKind> getNullability(const ASTContext &context) const;
 
  /// Determine whether the given type can have a nullability
  /// specifier applied to it, i.e., if it is any kind of pointer type.
  ///
  /// \param ResultIfUnknown The value to return if we don't yet know whether
  ///        this type can have nullability because it is dependent.
  bool canHaveNullability(bool ResultIfUnknown = true) const;
 
  /// Retrieve the set of substitutions required when accessing a member
  /// of the Objective-C receiver type that is declared in the given context.
  ///
  /// \c *this is the type of the object we're operating on, e.g., the
  /// receiver for a message send or the base of a property access, and is
  /// expected to be of some object or object pointer type.
  ///
  /// \param dc The declaration context for which we are building up a
  /// substitution mapping, which should be an Objective-C class, extension,
  /// category, or method within.
  ///
  /// \returns an array of type arguments that can be substituted for
  /// the type parameters of the given declaration context in any type described
  /// within that context, or an empty optional to indicate that no
  /// substitution is required.
  Optional<ArrayRef<QualType>>
  getObjCSubstitutions(const DeclContext *dc) const;
 
  /// Determines if this is an ObjC interface type that may accept type
  /// parameters.
  bool acceptsObjCTypeParams() const;
 
  const char *getTypeClassName() const;
 
  QualType getCanonicalTypeInternal() const {
    return CanonicalType;
  }
 
  CanQualType getCanonicalTypeUnqualified() const; // in CanonicalType.h
  void dump() const;
  void dump(llvm::raw_ostream &OS, const ASTContext &Context) const;
};
 
/// This will check for a TypedefType by removing any existing sugar
/// until it reaches a TypedefType or a non-sugared type.
template <> const TypedefType *Type::getAs() const;
 
/// This will check for a TemplateSpecializationType by removing any
/// existing sugar until it reaches a TemplateSpecializationType or a
/// non-sugared type.
template <> const TemplateSpecializationType *Type::getAs() const;
 
/// This will check for an AttributedType by removing any existing sugar
/// until it reaches an AttributedType or a non-sugared type.
template <> const AttributedType *Type::getAs() const;
 
// We can do canonical leaf types faster, because we don't have to
// worry about preserving child type decoration.
#define TYPE(Class, Base)
#define LEAF_TYPE(Class) \
template <> inline const Class##Type *Type::getAs() const { \
  return dyn_cast<Class##Type>(CanonicalType); \
} \
template <> inline const Class##Type *Type::castAs() const { \
  return cast<Class##Type>(CanonicalType); \
}
#include "clang/AST/TypeNodes.inc"
 
/// This class is used for builtin types like 'int'.  Builtin
/// types are always canonical and have a literal name field.
class BuiltinType : public Type {
public:
  enum Kind {
// OpenCL image types
#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) Id,
#include "clang/Basic/OpenCLImageTypes.def"
// OpenCL extension types
#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) Id,
#include "clang/Basic/OpenCLExtensionTypes.def"
// SVE Types
#define SVE_TYPE(Name, Id, SingletonId) Id,
#include "clang/Basic/AArch64SVEACLETypes.def"
// PPC MMA Types
#define PPC_VECTOR_TYPE(Name, Id, Size) Id,
#include "clang/Basic/PPCTypes.def"
// RVV Types
#define RVV_TYPE(Name, Id, SingletonId) Id,
#include "clang/Basic/RISCVVTypes.def"
// All other builtin types
#define BUILTIN_TYPE(Id, SingletonId) Id,
#define LAST_BUILTIN_TYPE(Id) LastKind = Id
#include "clang/AST/BuiltinTypes.def"
  };
 
private:
  friend class ASTContext; // ASTContext creates these.
 
  BuiltinType(Kind K)
      : Type(Builtin, QualType(),
             K == Dependent ? TypeDependence::DependentInstantiation
                            : TypeDependence::None) {
    BuiltinTypeBits.Kind = K;
  }
 
public:
  Kind getKind() const { return static_cast<Kind>(BuiltinTypeBits.Kind); }
  StringRef getName(const PrintingPolicy &Policy) const;
 
  const char *getNameAsCString(const PrintingPolicy &Policy) const {
    // The StringRef is null-terminated.
    StringRef str = getName(Policy);
    assert(!str.empty() && str.data()[str.size()] == '\0');
    return str.data();
  }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  bool isInteger() const {
    return getKind() >= Bool && getKind() <= Int128;
  }
 
  bool isSignedInteger() const {
    return getKind() >= Char_S && getKind() <= Int128;
  }
 
  bool isUnsignedInteger() const {
    return getKind() >= Bool && getKind() <= UInt128;
  }
 
  bool isFloatingPoint() const {
    return getKind() >= Half && getKind() <= Ibm128;
  }
 
  /// Determines whether the given kind corresponds to a placeholder type.
  static bool isPlaceholderTypeKind(Kind K) {
    return K >= Overload;
  }
 
  /// Determines whether this type is a placeholder type, i.e. a type
  /// which cannot appear in arbitrary positions in a fully-formed
  /// expression.
  bool isPlaceholderType() const {
    return isPlaceholderTypeKind(getKind());
  }
 
  /// Determines whether this type is a placeholder type other than
  /// Overload.  Most placeholder types require only syntactic
  /// information about their context in order to be resolved (e.g.
  /// whether it is a call expression), which means they can (and
  /// should) be resolved in an earlier "phase" of analysis.
  /// Overload expressions sometimes pick up further information
  /// from their context, like whether the context expects a
  /// specific function-pointer type, and so frequently need
  /// special treatment.
  bool isNonOverloadPlaceholderType() const {
    return getKind() > Overload;
  }
 
  static bool classof(const Type *T) { return T->getTypeClass() == Builtin; }
};
 
/// Complex values, per C99 6.2.5p11.  This supports the C99 complex
/// types (_Complex float etc) as well as the GCC integer complex extensions.
class ComplexType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext; // ASTContext creates these.
 
  QualType ElementType;
 
  ComplexType(QualType Element, QualType CanonicalPtr)
      : Type(Complex, CanonicalPtr, Element->getDependence()),
        ElementType(Element) {}
 
public:
  QualType getElementType() const { return ElementType; }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getElementType());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType Element) {
    ID.AddPointer(Element.getAsOpaquePtr());
  }
 
  static bool classof(const Type *T) { return T->getTypeClass() == Complex; }
};
 
/// Sugar for parentheses used when specifying types.
class ParenType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext; // ASTContext creates these.
 
  QualType Inner;
 
  ParenType(QualType InnerType, QualType CanonType)
      : Type(Paren, CanonType, InnerType->getDependence()), Inner(InnerType) {}
 
public:
  QualType getInnerType() const { return Inner; }
 
  bool isSugared() const { return true; }
  QualType desugar() const { return getInnerType(); }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getInnerType());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType Inner) {
    Inner.Profile(ID);
  }
 
  static bool classof(const Type *T) { return T->getTypeClass() == Paren; }
};
 
/// PointerType - C99 6.7.5.1 - Pointer Declarators.
class PointerType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext; // ASTContext creates these.
 
  QualType PointeeType;
 
  PointerType(QualType Pointee, QualType CanonicalPtr)
      : Type(Pointer, CanonicalPtr, Pointee->getDependence()),
        PointeeType(Pointee) {}
 
public:
  QualType getPointeeType() const { return PointeeType; }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getPointeeType());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType Pointee) {
    ID.AddPointer(Pointee.getAsOpaquePtr());
  }
 
  static bool classof(const Type *T) { return T->getTypeClass() == Pointer; }
};
 
/// Represents a type which was implicitly adjusted by the semantic
/// engine for arbitrary reasons.  For example, array and function types can
/// decay, and function types can have their calling conventions adjusted.
class AdjustedType : public Type, public llvm::FoldingSetNode {
  QualType OriginalTy;
  QualType AdjustedTy;
 
protected:
  friend class ASTContext; // ASTContext creates these.
 
  AdjustedType(TypeClass TC, QualType OriginalTy, QualType AdjustedTy,
               QualType CanonicalPtr)
      : Type(TC, CanonicalPtr, OriginalTy->getDependence()),
        OriginalTy(OriginalTy), AdjustedTy(AdjustedTy) {}
 
public:
  QualType getOriginalType() const { return OriginalTy; }
  QualType getAdjustedType() const { return AdjustedTy; }
 
  bool isSugared() const { return true; }
  QualType desugar() const { return AdjustedTy; }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, OriginalTy, AdjustedTy);
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType Orig, QualType New) {
    ID.AddPointer(Orig.getAsOpaquePtr());
    ID.AddPointer(New.getAsOpaquePtr());
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == Adjusted || T->getTypeClass() == Decayed;
  }
};
 
/// Represents a pointer type decayed from an array or function type.
class DecayedType : public AdjustedType {
  friend class ASTContext; // ASTContext creates these.
 
  inline
  DecayedType(QualType OriginalType, QualType Decayed, QualType Canonical);
 
public:
  QualType getDecayedType() const { return getAdjustedType(); }
 
  inline QualType getPointeeType() const;
 
  static bool classof(const Type *T) { return T->getTypeClass() == Decayed; }
};
 
/// Pointer to a block type.
/// This type is to represent types syntactically represented as
/// "void (^)(int)", etc. Pointee is required to always be a function type.
class BlockPointerType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext; // ASTContext creates these.
 
  // Block is some kind of pointer type
  QualType PointeeType;
 
  BlockPointerType(QualType Pointee, QualType CanonicalCls)
      : Type(BlockPointer, CanonicalCls, Pointee->getDependence()),
        PointeeType(Pointee) {}
 
public:
  // Get the pointee type. Pointee is required to always be a function type.
  QualType getPointeeType() const { return PointeeType; }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
      Profile(ID, getPointeeType());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType Pointee) {
      ID.AddPointer(Pointee.getAsOpaquePtr());
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == BlockPointer;
  }
};
 
/// Base for LValueReferenceType and RValueReferenceType
class ReferenceType : public Type, public llvm::FoldingSetNode {
  QualType PointeeType;
 
protected:
  ReferenceType(TypeClass tc, QualType Referencee, QualType CanonicalRef,
                bool SpelledAsLValue)
      : Type(tc, CanonicalRef, Referencee->getDependence()),
        PointeeType(Referencee) {
    ReferenceTypeBits.SpelledAsLValue = SpelledAsLValue;
    ReferenceTypeBits.InnerRef = Referencee->isReferenceType();
  }
 
public:
  bool isSpelledAsLValue() const { return ReferenceTypeBits.SpelledAsLValue; }
  bool isInnerRef() const { return ReferenceTypeBits.InnerRef; }
 
  QualType getPointeeTypeAsWritten() const { return PointeeType; }
 
  QualType getPointeeType() const {
    // FIXME: this might strip inner qualifiers; okay?
    const ReferenceType *T = this;
    while (T->isInnerRef())
      T = T->PointeeType->castAs<ReferenceType>();
    return T->PointeeType;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, PointeeType, isSpelledAsLValue());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID,
                      QualType Referencee,
                      bool SpelledAsLValue) {
    ID.AddPointer(Referencee.getAsOpaquePtr());
    ID.AddBoolean(SpelledAsLValue);
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == LValueReference ||
           T->getTypeClass() == RValueReference;
  }
};
 
/// An lvalue reference type, per C++11 [dcl.ref].
class LValueReferenceType : public ReferenceType {
  friend class ASTContext; // ASTContext creates these
 
  LValueReferenceType(QualType Referencee, QualType CanonicalRef,
                      bool SpelledAsLValue)
      : ReferenceType(LValueReference, Referencee, CanonicalRef,
                      SpelledAsLValue) {}
 
public:
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == LValueReference;
  }
};
 
/// An rvalue reference type, per C++11 [dcl.ref].
class RValueReferenceType : public ReferenceType {
  friend class ASTContext; // ASTContext creates these
 
  RValueReferenceType(QualType Referencee, QualType CanonicalRef)
       : ReferenceType(RValueReference, Referencee, CanonicalRef, false) {}
 
public:
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == RValueReference;
  }
};
 
/// A pointer to member type per C++ 8.3.3 - Pointers to members.
///
/// This includes both pointers to data members and pointer to member functions.
class MemberPointerType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext; // ASTContext creates these.
 
  QualType PointeeType;
 
  /// The class of which the pointee is a member. Must ultimately be a
  /// RecordType, but could be a typedef or a template parameter too.
  const Type *Class;
 
  MemberPointerType(QualType Pointee, const Type *Cls, QualType CanonicalPtr)
      : Type(MemberPointer, CanonicalPtr,
             (Cls->getDependence() & ~TypeDependence::VariablyModified) |
                 Pointee->getDependence()),
        PointeeType(Pointee), Class(Cls) {}
 
public:
  QualType getPointeeType() const { return PointeeType; }
 
  /// Returns true if the member type (i.e. the pointee type) is a
  /// function type rather than a data-member type.
  bool isMemberFunctionPointer() const {
    return PointeeType->isFunctionProtoType();
  }
 
  /// Returns true if the member type (i.e. the pointee type) is a
  /// data type rather than a function type.
  bool isMemberDataPointer() const {
    return !PointeeType->isFunctionProtoType();
  }
 
  const Type *getClass() const { return Class; }
  CXXRecordDecl *getMostRecentCXXRecordDecl() const;
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getPointeeType(), getClass());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType Pointee,
                      const Type *Class) {
    ID.AddPointer(Pointee.getAsOpaquePtr());
    ID.AddPointer(Class);
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == MemberPointer;
  }
};
 
/// Represents an array type, per C99 6.7.5.2 - Array Declarators.
class ArrayType : public Type, public llvm::FoldingSetNode {
public:
  /// Capture whether this is a normal array (e.g. int X[4])
  /// an array with a static size (e.g. int X[static 4]), or an array
  /// with a star size (e.g. int X[*]).
  /// 'static' is only allowed on function parameters.
  enum ArraySizeModifier {
    Normal, Static, Star
  };
 
private:
  /// The element type of the array.
  QualType ElementType;
 
protected:
  friend class ASTContext; // ASTContext creates these.
 
  ArrayType(TypeClass tc, QualType et, QualType can, ArraySizeModifier sm,
            unsigned tq, const Expr *sz = nullptr);
 
public:
  QualType getElementType() const { return ElementType; }
 
  ArraySizeModifier getSizeModifier() const {
    return ArraySizeModifier(ArrayTypeBits.SizeModifier);
  }
 
  Qualifiers getIndexTypeQualifiers() const {
    return Qualifiers::fromCVRMask(getIndexTypeCVRQualifiers());
  }
 
  unsigned getIndexTypeCVRQualifiers() const {
    return ArrayTypeBits.IndexTypeQuals;
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == ConstantArray ||
           T->getTypeClass() == VariableArray ||
           T->getTypeClass() == IncompleteArray ||
           T->getTypeClass() == DependentSizedArray;
  }
};
 
/// Represents the canonical version of C arrays with a specified constant size.
/// For example, the canonical type for 'int A[4 + 4*100]' is a
/// ConstantArrayType where the element type is 'int' and the size is 404.
class ConstantArrayType final
    : public ArrayType,
      private llvm::TrailingObjects<ConstantArrayType, const Expr *> {
  friend class ASTContext; // ASTContext creates these.
  friend TrailingObjects;
 
  llvm::APInt Size; // Allows us to unique the type.
 
  ConstantArrayType(QualType et, QualType can, const llvm::APInt &size,
                    const Expr *sz, ArraySizeModifier sm, unsigned tq)
      : ArrayType(ConstantArray, et, can, sm, tq, sz), Size(size) {
    ConstantArrayTypeBits.HasStoredSizeExpr = sz != nullptr;
    if (ConstantArrayTypeBits.HasStoredSizeExpr) {
      assert(!can.isNull() && "canonical constant array should not have size");
      *getTrailingObjects<const Expr*>() = sz;
    }
  }
 
  unsigned numTrailingObjects(OverloadToken<const Expr*>) const {
    return ConstantArrayTypeBits.HasStoredSizeExpr;
  }
 
public:
  const llvm::APInt &getSize() const { return Size; }
  const Expr *getSizeExpr() const {
    return ConstantArrayTypeBits.HasStoredSizeExpr
               ? *getTrailingObjects<const Expr *>()
               : nullptr;
  }
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  /// Determine the number of bits required to address a member of
  // an array with the given element type and number of elements.
  static unsigned getNumAddressingBits(const ASTContext &Context,
                                       QualType ElementType,
                                       const llvm::APInt &NumElements);
 
  /// Determine the maximum number of active bits that an array's size
  /// can require, which limits the maximum size of the array.
  static unsigned getMaxSizeBits(const ASTContext &Context);
 
  void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx) {
    Profile(ID, Ctx, getElementType(), getSize(), getSizeExpr(),
            getSizeModifier(), getIndexTypeCVRQualifiers());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx,
                      QualType ET, const llvm::APInt &ArraySize,
                      const Expr *SizeExpr, ArraySizeModifier SizeMod,
                      unsigned TypeQuals);
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == ConstantArray;
  }
};
 
/// Represents a C array with an unspecified size.  For example 'int A[]' has
/// an IncompleteArrayType where the element type is 'int' and the size is
/// unspecified.
class IncompleteArrayType : public ArrayType {
  friend class ASTContext; // ASTContext creates these.
 
  IncompleteArrayType(QualType et, QualType can,
                      ArraySizeModifier sm, unsigned tq)
      : ArrayType(IncompleteArray, et, can, sm, tq) {}
 
public:
  friend class StmtIteratorBase;
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == IncompleteArray;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getElementType(), getSizeModifier(),
            getIndexTypeCVRQualifiers());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType ET,
                      ArraySizeModifier SizeMod, unsigned TypeQuals) {
    ID.AddPointer(ET.getAsOpaquePtr());
    ID.AddInteger(SizeMod);
    ID.AddInteger(TypeQuals);
  }
};
 
/// Represents a C array with a specified size that is not an
/// integer-constant-expression.  For example, 'int s[x+foo()]'.
/// Since the size expression is an arbitrary expression, we store it as such.
///
/// Note: VariableArrayType's aren't uniqued (since the expressions aren't) and
/// should not be: two lexically equivalent variable array types could mean
/// different things, for example, these variables do not have the same type
/// dynamically:
///
/// void foo(int x) {
///   int Y[x];
///   ++x;
///   int Z[x];
/// }
class VariableArrayType : public ArrayType {
  friend class ASTContext; // ASTContext creates these.
 
  /// An assignment-expression. VLA's are only permitted within
  /// a function block.
  Stmt *SizeExpr;
 
  /// The range spanned by the left and right array brackets.
  SourceRange Brackets;
 
  VariableArrayType(QualType et, QualType can, Expr *e,
                    ArraySizeModifier sm, unsigned tq,
                    SourceRange brackets)
      : ArrayType(VariableArray, et, can, sm, tq, e),
        SizeExpr((Stmt*) e), Brackets(brackets) {}
 
public:
  friend class StmtIteratorBase;
 
  Expr *getSizeExpr() const {
    // We use C-style casts instead of cast<> here because we do not wish
    // to have a dependency of Type.h on Stmt.h/Expr.h.
    return (Expr*) SizeExpr;
  }
 
  SourceRange getBracketsRange() const { return Brackets; }
  SourceLocation getLBracketLoc() const { return Brackets.getBegin(); }
  SourceLocation getRBracketLoc() const { return Brackets.getEnd(); }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == VariableArray;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    llvm_unreachable("Cannot unique VariableArrayTypes.");
  }
};
 
/// Represents an array type in C++ whose size is a value-dependent expression.
///
/// For example:
/// \code
/// template<typename T, int Size>
/// class array {
///   T data[Size];
/// };
/// \endcode
///
/// For these types, we won't actually know what the array bound is
/// until template instantiation occurs, at which point this will
/// become either a ConstantArrayType or a VariableArrayType.
class DependentSizedArrayType : public ArrayType {
  friend class ASTContext; // ASTContext creates these.
 
  const ASTContext &Context;
 
  /// An assignment expression that will instantiate to the
  /// size of the array.
  ///
  /// The expression itself might be null, in which case the array
  /// type will have its size deduced from an initializer.
  Stmt *SizeExpr;
 
  /// The range spanned by the left and right array brackets.
  SourceRange Brackets;
 
  DependentSizedArrayType(const ASTContext &Context, QualType et, QualType can,
                          Expr *e, ArraySizeModifier sm, unsigned tq,
                          SourceRange brackets);
 
public:
  friend class StmtIteratorBase;
 
  Expr *getSizeExpr() const {
    // We use C-style casts instead of cast<> here because we do not wish
    // to have a dependency of Type.h on Stmt.h/Expr.h.
    return (Expr*) SizeExpr;
  }
 
  SourceRange getBracketsRange() const { return Brackets; }
  SourceLocation getLBracketLoc() const { return Brackets.getBegin(); }
  SourceLocation getRBracketLoc() const { return Brackets.getEnd(); }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == DependentSizedArray;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, Context, getElementType(),
            getSizeModifier(), getIndexTypeCVRQualifiers(), getSizeExpr());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      QualType ET, ArraySizeModifier SizeMod,
                      unsigned TypeQuals, Expr *E);
};
 
/// Represents an extended address space qualifier where the input address space
/// value is dependent. Non-dependent address spaces are not represented with a
/// special Type subclass; they are stored on an ExtQuals node as part of a QualType.
///
/// For example:
/// \code
/// template<typename T, int AddrSpace>
/// class AddressSpace {
///   typedef T __attribute__((address_space(AddrSpace))) type;
/// }
/// \endcode
class DependentAddressSpaceType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext;
 
  const ASTContext &Context;
  Expr *AddrSpaceExpr;
  QualType PointeeType;
  SourceLocation loc;
 
  DependentAddressSpaceType(const ASTContext &Context, QualType PointeeType,
                            QualType can, Expr *AddrSpaceExpr,
                            SourceLocation loc);
 
public:
  Expr *getAddrSpaceExpr() const { return AddrSpaceExpr; }
  QualType getPointeeType() const { return PointeeType; }
  SourceLocation getAttributeLoc() const { return loc; }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == DependentAddressSpace;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, Context, getPointeeType(), getAddrSpaceExpr());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      QualType PointeeType, Expr *AddrSpaceExpr);
};
 
/// Represents an extended vector type where either the type or size is
/// dependent.
///
/// For example:
/// \code
/// template<typename T, int Size>
/// class vector {
///   typedef T __attribute__((ext_vector_type(Size))) type;
/// }
/// \endcode
class DependentSizedExtVectorType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext;
 
  const ASTContext &Context;
  Expr *SizeExpr;
 
  /// The element type of the array.
  QualType ElementType;
 
  SourceLocation loc;
 
  DependentSizedExtVectorType(const ASTContext &Context, QualType ElementType,
                              QualType can, Expr *SizeExpr, SourceLocation loc);
 
public:
  Expr *getSizeExpr() const { return SizeExpr; }
  QualType getElementType() const { return ElementType; }
  SourceLocation getAttributeLoc() const { return loc; }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == DependentSizedExtVector;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, Context, getElementType(), getSizeExpr());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      QualType ElementType, Expr *SizeExpr);
};
 
 
/// Represents a GCC generic vector type. This type is created using
/// __attribute__((vector_size(n)), where "n" specifies the vector size in
/// bytes; or from an Altivec __vector or vector declaration.
/// Since the constructor takes the number of vector elements, the
/// client is responsible for converting the size into the number of elements.
class VectorType : public Type, public llvm::FoldingSetNode {
public:
  enum VectorKind {
    /// not a target-specific vector type
    GenericVector,
 
    /// is AltiVec vector
    AltiVecVector,
 
    /// is AltiVec 'vector Pixel'
    AltiVecPixel,
 
    /// is AltiVec 'vector bool ...'
    AltiVecBool,
 
    /// is ARM Neon vector
    NeonVector,
 
    /// is ARM Neon polynomial vector
    NeonPolyVector,
 
    /// is AArch64 SVE fixed-length data vector
    SveFixedLengthDataVector,
 
    /// is AArch64 SVE fixed-length predicate vector
    SveFixedLengthPredicateVector
  };
 
protected:
  friend class ASTContext; // ASTContext creates these.
 
  /// The element type of the vector.
  QualType ElementType;
 
  VectorType(QualType vecType, unsigned nElements, QualType canonType,
             VectorKind vecKind);
 
  VectorType(TypeClass tc, QualType vecType, unsigned nElements,
             QualType canonType, VectorKind vecKind);
 
public:
  QualType getElementType() const { return ElementType; }
  unsigned getNumElements() const { return VectorTypeBits.NumElements; }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  VectorKind getVectorKind() const {
    return VectorKind(VectorTypeBits.VecKind);
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getElementType(), getNumElements(),
            getTypeClass(), getVectorKind());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType ElementType,
                      unsigned NumElements, TypeClass TypeClass,
                      VectorKind VecKind) {
    ID.AddPointer(ElementType.getAsOpaquePtr());
    ID.AddInteger(NumElements);
    ID.AddInteger(TypeClass);
    ID.AddInteger(VecKind);
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == Vector || T->getTypeClass() == ExtVector;
  }
};
 
/// Represents a vector type where either the type or size is dependent.
////
/// For example:
/// \code
/// template<typename T, int Size>
/// class vector {
///   typedef T __attribute__((vector_size(Size))) type;
/// }
/// \endcode
class DependentVectorType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext;
 
  const ASTContext &Context;
  QualType ElementType;
  Expr *SizeExpr;
  SourceLocation Loc;
 
  DependentVectorType(const ASTContext &Context, QualType ElementType,
                           QualType CanonType, Expr *SizeExpr,
                           SourceLocation Loc, VectorType::VectorKind vecKind);
 
public:
  Expr *getSizeExpr() const { return SizeExpr; }
  QualType getElementType() const { return ElementType; }
  SourceLocation getAttributeLoc() const { return Loc; }
  VectorType::VectorKind getVectorKind() const {
    return VectorType::VectorKind(VectorTypeBits.VecKind);
  }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == DependentVector;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, Context, getElementType(), getSizeExpr(), getVectorKind());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      QualType ElementType, const Expr *SizeExpr,
                      VectorType::VectorKind VecKind);
};
 
/// ExtVectorType - Extended vector type. This type is created using
/// __attribute__((ext_vector_type(n)), where "n" is the number of elements.
/// Unlike vector_size, ext_vector_type is only allowed on typedef's. This
/// class enables syntactic extensions, like Vector Components for accessing
/// points (as .xyzw), colors (as .rgba), and textures (modeled after OpenGL
/// Shading Language).
class ExtVectorType : public VectorType {
  friend class ASTContext; // ASTContext creates these.
 
  ExtVectorType(QualType vecType, unsigned nElements, QualType canonType)
      : VectorType(ExtVector, vecType, nElements, canonType, GenericVector) {}
 
public:
  static int getPointAccessorIdx(char c) {
    switch (c) {
    default: return -1;
    case 'x': case 'r': return 0;
    case 'y': case 'g': return 1;
    case 'z': case 'b': return 2;
    case 'w': case 'a': return 3;
    }
  }
 
  static int getNumericAccessorIdx(char c) {
    switch (c) {
      default: return -1;
      case '0': return 0;
      case '1': return 1;
      case '2': return 2;
      case '3': return 3;
      case '4': return 4;
      case '5': return 5;
      case '6': return 6;
      case '7': return 7;
      case '8': return 8;
      case '9': return 9;
      case 'A':
      case 'a': return 10;
      case 'B':
      case 'b': return 11;
      case 'C':
      case 'c': return 12;
      case 'D':
      case 'd': return 13;
      case 'E':
      case 'e': return 14;
      case 'F':
      case 'f': return 15;
    }
  }
 
  static int getAccessorIdx(char c, bool isNumericAccessor) {
    if (isNumericAccessor)
      return getNumericAccessorIdx(c);
    else
      return getPointAccessorIdx(c);
  }
 
  bool isAccessorWithinNumElements(char c, bool isNumericAccessor) const {
    if (int idx = getAccessorIdx(c, isNumericAccessor)+1)
      return unsigned(idx-1) < getNumElements();
    return false;
  }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == ExtVector;
  }
};
 
/// Represents a matrix type, as defined in the Matrix Types clang extensions.
/// __attribute__((matrix_type(rows, columns))), where "rows" specifies
/// number of rows and "columns" specifies the number of columns.
class MatrixType : public Type, public llvm::FoldingSetNode {
protected:
  friend class ASTContext;
 
  /// The element type of the matrix.
  QualType ElementType;
 
  MatrixType(QualType ElementTy, QualType CanonElementTy);
 
  MatrixType(TypeClass TypeClass, QualType ElementTy, QualType CanonElementTy,
             const Expr *RowExpr = nullptr, const Expr *ColumnExpr = nullptr);
 
public:
  /// Returns type of the elements being stored in the matrix
  QualType getElementType() const { return ElementType; }
 
  /// Valid elements types are the following:
  /// * an integer type (as in C2x 6.2.5p19), but excluding enumerated types
  ///   and _Bool
  /// * the standard floating types float or double
  /// * a half-precision floating point type, if one is supported on the target
  static bool isValidElementType(QualType T) {
    return T->isDependentType() ||
           (T->isRealType() && !T->isBooleanType() && !T->isEnumeralType());
  }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == ConstantMatrix ||
           T->getTypeClass() == DependentSizedMatrix;
  }
};
 
/// Represents a concrete matrix type with constant number of rows and columns
class ConstantMatrixType final : public MatrixType {
protected:
  friend class ASTContext;
 
  /// Number of rows and columns.
  unsigned NumRows;
  unsigned NumColumns;
 
  static constexpr unsigned MaxElementsPerDimension = (1 << 20) - 1;
 
  ConstantMatrixType(QualType MatrixElementType, unsigned NRows,
                     unsigned NColumns, QualType CanonElementType);
 
  ConstantMatrixType(TypeClass typeClass, QualType MatrixType, unsigned NRows,
                     unsigned NColumns, QualType CanonElementType);
 
public:
  /// Returns the number of rows in the matrix.
  unsigned getNumRows() const { return NumRows; }
 
  /// Returns the number of columns in the matrix.
  unsigned getNumColumns() const { return NumColumns; }
 
  /// Returns the number of elements required to embed the matrix into a vector.
  unsigned getNumElementsFlattened() const {
    return getNumRows() * getNumColumns();
  }
 
  /// Returns true if \p NumElements is a valid matrix dimension.
  static constexpr bool isDimensionValid(size_t NumElements) {
    return NumElements > 0 && NumElements <= MaxElementsPerDimension;
  }
 
  /// Returns the maximum number of elements per dimension.
  static constexpr unsigned getMaxElementsPerDimension() {
    return MaxElementsPerDimension;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getElementType(), getNumRows(), getNumColumns(),
            getTypeClass());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType ElementType,
                      unsigned NumRows, unsigned NumColumns,
                      TypeClass TypeClass) {
    ID.AddPointer(ElementType.getAsOpaquePtr());
    ID.AddInteger(NumRows);
    ID.AddInteger(NumColumns);
    ID.AddInteger(TypeClass);
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == ConstantMatrix;
  }
};
 
/// Represents a matrix type where the type and the number of rows and columns
/// is dependent on a template.
class DependentSizedMatrixType final : public MatrixType {
  friend class ASTContext;
 
  const ASTContext &Context;
  Expr *RowExpr;
  Expr *ColumnExpr;
 
  SourceLocation loc;
 
  DependentSizedMatrixType(const ASTContext &Context, QualType ElementType,
                           QualType CanonicalType, Expr *RowExpr,
                           Expr *ColumnExpr, SourceLocation loc);
 
public:
  Expr *getRowExpr() const { return RowExpr; }
  Expr *getColumnExpr() const { return ColumnExpr; }
  SourceLocation getAttributeLoc() const { return loc; }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == DependentSizedMatrix;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, Context, getElementType(), getRowExpr(), getColumnExpr());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      QualType ElementType, Expr *RowExpr, Expr *ColumnExpr);
};
 
/// FunctionType - C99 6.7.5.3 - Function Declarators.  This is the common base
/// class of FunctionNoProtoType and FunctionProtoType.
class FunctionType : public Type {
  // The type returned by the function.
  QualType ResultType;
 
public:
  /// Interesting information about a specific parameter that can't simply
  /// be reflected in parameter's type. This is only used by FunctionProtoType
  /// but is in FunctionType to make this class available during the
  /// specification of the bases of FunctionProtoType.
  ///
  /// It makes sense to model language features this way when there's some
  /// sort of parameter-specific override (such as an attribute) that
  /// affects how the function is called.  For example, the ARC ns_consumed
  /// attribute changes whether a parameter is passed at +0 (the default)
  /// or +1 (ns_consumed).  This must be reflected in the function type,
  /// but isn't really a change to the parameter type.
  ///
  /// One serious disadvantage of modelling language features this way is
  /// that they generally do not work with language features that attempt
  /// to destructure types.  For example, template argument deduction will
  /// not be able to match a parameter declared as
  ///   T (*)(U)
  /// against an argument of type
  ///   void (*)(__attribute__((ns_consumed)) id)
  /// because the substitution of T=void, U=id into the former will
  /// not produce the latter.
  class ExtParameterInfo {
    enum {
      ABIMask = 0x0F,
      IsConsumed = 0x10,
      HasPassObjSize = 0x20,
      IsNoEscape = 0x40,
    };
    unsigned char Data = 0;
 
  public:
    ExtParameterInfo() = default;
 
    /// Return the ABI treatment of this parameter.
    ParameterABI getABI() const { return ParameterABI(Data & ABIMask); }
    ExtParameterInfo withABI(ParameterABI kind) const {
      ExtParameterInfo copy = *this;
      copy.Data = (copy.Data & ~ABIMask) | unsigned(kind);
      return copy;
    }
 
    /// Is this parameter considered "consumed" by Objective-C ARC?
    /// Consumed parameters must have retainable object type.
    bool isConsumed() const { return (Data & IsConsumed); }
    ExtParameterInfo withIsConsumed(bool consumed) const {
      ExtParameterInfo copy = *this;
      if (consumed)
        copy.Data |= IsConsumed;
      else
        copy.Data &= ~IsConsumed;
      return copy;
    }
 
    bool hasPassObjectSize() const { return Data & HasPassObjSize; }
    ExtParameterInfo withHasPassObjectSize() const {
      ExtParameterInfo Copy = *this;
      Copy.Data |= HasPassObjSize;
      return Copy;
    }
 
    bool isNoEscape() const { return Data & IsNoEscape; }
    ExtParameterInfo withIsNoEscape(bool NoEscape) const {
      ExtParameterInfo Copy = *this;
      if (NoEscape)
        Copy.Data |= IsNoEscape;
      else
        Copy.Data &= ~IsNoEscape;
      return Copy;
    }
 
    unsigned char getOpaqueValue() const { return Data; }
    static ExtParameterInfo getFromOpaqueValue(unsigned char data) {
      ExtParameterInfo result;
      result.Data = data;
      return result;
    }
 
    friend bool operator==(ExtParameterInfo lhs, ExtParameterInfo rhs) {
      return lhs.Data == rhs.Data;
    }
 
    friend bool operator!=(ExtParameterInfo lhs, ExtParameterInfo rhs) {
      return lhs.Data != rhs.Data;
    }
  };
 
  /// A class which abstracts out some details necessary for
  /// making a call.
  ///
  /// It is not actually used directly for storing this information in
  /// a FunctionType, although FunctionType does currently use the
  /// same bit-pattern.
  ///
  // If you add a field (say Foo), other than the obvious places (both,
  // constructors, compile failures), what you need to update is
  // * Operator==
  // * getFoo
  // * withFoo
  // * functionType. Add Foo, getFoo.
  // * ASTContext::getFooType
  // * ASTContext::mergeFunctionTypes
  // * FunctionNoProtoType::Profile
  // * FunctionProtoType::Profile
  // * TypePrinter::PrintFunctionProto
  // * AST read and write
  // * Codegen
  class ExtInfo {
    friend class FunctionType;
 
    // Feel free to rearrange or add bits, but if you go over 16, you'll need to
    // adjust the Bits field below, and if you add bits, you'll need to adjust
    // Type::FunctionTypeBitfields::ExtInfo as well.
 
    // |  CC  |noreturn|produces|nocallersavedregs|regparm|nocfcheck|cmsenscall|
    // |0 .. 4|   5    |    6   |       7         |8 .. 10|    11   |    12    |
    //
    // regparm is either 0 (no regparm attribute) or the regparm value+1.
    enum { CallConvMask = 0x1F };
    enum { NoReturnMask = 0x20 };
    enum { ProducesResultMask = 0x40 };
    enum { NoCallerSavedRegsMask = 0x80 };
    enum {
      RegParmMask =  0x700,
      RegParmOffset = 8
    };
    enum { NoCfCheckMask = 0x800 };
    enum { CmseNSCallMask = 0x1000 };
    uint16_t Bits = CC_C;
 
    ExtInfo(unsigned Bits) : Bits(static_cast<uint16_t>(Bits)) {}
 
  public:
    // Constructor with no defaults. Use this when you know that you
    // have all the elements (when reading an AST file for example).
    ExtInfo(bool noReturn, bool hasRegParm, unsigned regParm, CallingConv cc,
            bool producesResult, bool noCallerSavedRegs, bool NoCfCheck,
            bool cmseNSCall) {
      assert((!hasRegParm || regParm < 7) && "Invalid regparm value");
      Bits = ((unsigned)cc) | (noReturn ? NoReturnMask : 0) |
             (producesResult ? ProducesResultMask : 0) |
             (noCallerSavedRegs ? NoCallerSavedRegsMask : 0) |
             (hasRegParm ? ((regParm + 1) << RegParmOffset) : 0) |
             (NoCfCheck ? NoCfCheckMask : 0) |
             (cmseNSCall ? CmseNSCallMask : 0);
    }
 
    // Constructor with all defaults. Use when for example creating a
    // function known to use defaults.
    ExtInfo() = default;
 
    // Constructor with just the calling convention, which is an important part
    // of the canonical type.
    ExtInfo(CallingConv CC) : Bits(CC) {}
 
    bool getNoReturn() const { return Bits & NoReturnMask; }
    bool getProducesResult() const { return Bits & ProducesResultMask; }
    bool getCmseNSCall() const { return Bits & CmseNSCallMask; }
    bool getNoCallerSavedRegs() const { return Bits & NoCallerSavedRegsMask; }
    bool getNoCfCheck() const { return Bits & NoCfCheckMask; }
    bool getHasRegParm() const { return ((Bits & RegParmMask) >> RegParmOffset) != 0; }
 
    unsigned getRegParm() const {
      unsigned RegParm = (Bits & RegParmMask) >> RegParmOffset;
      if (RegParm > 0)
        --RegParm;
      return RegParm;
    }
 
    CallingConv getCC() const { return CallingConv(Bits & CallConvMask); }
 
    bool operator==(ExtInfo Other) const {
      return Bits == Other.Bits;
    }
    bool operator!=(ExtInfo Other) const {
      return Bits != Other.Bits;
    }
 
    // Note that we don't have setters. That is by design, use
    // the following with methods instead of mutating these objects.
 
    ExtInfo withNoReturn(bool noReturn) const {
      if (noReturn)
        return ExtInfo(Bits | NoReturnMask);
      else
        return ExtInfo(Bits & ~NoReturnMask);
    }
 
    ExtInfo withProducesResult(bool producesResult) const {
      if (producesResult)
        return ExtInfo(Bits | ProducesResultMask);
      else
        return ExtInfo(Bits & ~ProducesResultMask);
    }
 
    ExtInfo withCmseNSCall(bool cmseNSCall) const {
      if (cmseNSCall)
        return ExtInfo(Bits | CmseNSCallMask);
      else
        return ExtInfo(Bits & ~CmseNSCallMask);
    }
 
    ExtInfo withNoCallerSavedRegs(bool noCallerSavedRegs) const {
      if (noCallerSavedRegs)
        return ExtInfo(Bits | NoCallerSavedRegsMask);
      else
        return ExtInfo(Bits & ~NoCallerSavedRegsMask);
    }
 
    ExtInfo withNoCfCheck(bool noCfCheck) const {
      if (noCfCheck)
        return ExtInfo(Bits | NoCfCheckMask);
      else
        return ExtInfo(Bits & ~NoCfCheckMask);
    }
 
    ExtInfo withRegParm(unsigned RegParm) const {
      assert(RegParm < 7 && "Invalid regparm value");
      return ExtInfo((Bits & ~RegParmMask) |
                     ((RegParm + 1) << RegParmOffset));
    }
 
    ExtInfo withCallingConv(CallingConv cc) const {
      return ExtInfo((Bits & ~CallConvMask) | (unsigned) cc);
    }
 
    void Profile(llvm::FoldingSetNodeID &ID) const {
      ID.AddInteger(Bits);
    }
  };
 
  /// A simple holder for a QualType representing a type in an
  /// exception specification. Unfortunately needed by FunctionProtoType
  /// because TrailingObjects cannot handle repeated types.
  struct ExceptionType { QualType Type; };
 
  /// A simple holder for various uncommon bits which do not fit in
  /// FunctionTypeBitfields. Aligned to alignof(void *) to maintain the
  /// alignment of subsequent objects in TrailingObjects. You must update
  /// hasExtraBitfields in FunctionProtoType after adding extra data here.
  struct alignas(void *) FunctionTypeExtraBitfields {
    /// The number of types in the exception specification.
    /// A whole unsigned is not needed here and according to
    /// [implimits] 8 bits would be enough here.
    unsigned NumExceptionType;
  };
 
protected:
  FunctionType(TypeClass tc, QualType res, QualType Canonical,
               TypeDependence Dependence, ExtInfo Info)
      : Type(tc, Canonical, Dependence), ResultType(res) {
    FunctionTypeBits.ExtInfo = Info.Bits;
  }
 
  Qualifiers getFastTypeQuals() const {
    return Qualifiers::fromFastMask(FunctionTypeBits.FastTypeQuals);
  }
 
public:
  QualType getReturnType() const { return ResultType; }
 
  bool getHasRegParm() const { return getExtInfo().getHasRegParm(); }
  unsigned getRegParmType() const { return getExtInfo().getRegParm(); }
 
  /// Determine whether this function type includes the GNU noreturn
  /// attribute. The C++11 [[noreturn]] attribute does not affect the function
  /// type.
  bool getNoReturnAttr() const { return getExtInfo().getNoReturn(); }
 
  bool getCmseNSCallAttr() const { return getExtInfo().getCmseNSCall(); }
  CallingConv getCallConv() const { return getExtInfo().getCC(); }
  ExtInfo getExtInfo() const { return ExtInfo(FunctionTypeBits.ExtInfo); }
 
  static_assert((~Qualifiers::FastMask & Qualifiers::CVRMask) == 0,
                "Const, volatile and restrict are assumed to be a subset of "
                "the fast qualifiers.");
 
  bool isConst() const { return getFastTypeQuals().hasConst(); }
  bool isVolatile() const { return getFastTypeQuals().hasVolatile(); }
  bool isRestrict() const { return getFastTypeQuals().hasRestrict(); }
 
  /// Determine the type of an expression that calls a function of
  /// this type.
  QualType getCallResultType(const ASTContext &Context) const {
    return getReturnType().getNonLValueExprType(Context);
  }
 
  static StringRef getNameForCallConv(CallingConv CC);
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == FunctionNoProto ||
           T->getTypeClass() == FunctionProto;
  }
};
 
/// Represents a K&R-style 'int foo()' function, which has
/// no information available about its arguments.
class FunctionNoProtoType : public FunctionType, public llvm::FoldingSetNode {
  friend class ASTContext; // ASTContext creates these.
 
  FunctionNoProtoType(QualType Result, QualType Canonical, ExtInfo Info)
      : FunctionType(FunctionNoProto, Result, Canonical,
                     Result->getDependence() &
                         ~(TypeDependence::DependentInstantiation |
                           TypeDependence::UnexpandedPack),
                     Info) {}
 
public:
  // No additional state past what FunctionType provides.
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getReturnType(), getExtInfo());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType ResultType,
                      ExtInfo Info) {
    Info.Profile(ID);
    ID.AddPointer(ResultType.getAsOpaquePtr());
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == FunctionNoProto;
  }
};
 
/// Represents a prototype with parameter type info, e.g.
/// 'int foo(int)' or 'int foo(void)'.  'void' is represented as having no
/// parameters, not as having a single void parameter. Such a type can have
/// an exception specification, but this specification is not part of the
/// canonical type. FunctionProtoType has several trailing objects, some of
/// which optional. For more information about the trailing objects see
/// the first comment inside FunctionProtoType.
class FunctionProtoType final
    : public FunctionType,
      public llvm::FoldingSetNode,
      private llvm::TrailingObjects<
          FunctionProtoType, QualType, SourceLocation,
          FunctionType::FunctionTypeExtraBitfields, FunctionType::ExceptionType,
          Expr *, FunctionDecl *, FunctionType::ExtParameterInfo, Qualifiers> {
  friend class ASTContext; // ASTContext creates these.
  friend TrailingObjects;
 
  // FunctionProtoType is followed by several trailing objects, some of
  // which optional. They are in order:
  //
  // * An array of getNumParams() QualType holding the parameter types.
  //   Always present. Note that for the vast majority of FunctionProtoType,
  //   these will be the only trailing objects.
  //
  // * Optionally if the function is variadic, the SourceLocation of the
  //   ellipsis.
  //
  // * Optionally if some extra data is stored in FunctionTypeExtraBitfields
  //   (see FunctionTypeExtraBitfields and FunctionTypeBitfields):
  //   a single FunctionTypeExtraBitfields. Present if and only if
  //   hasExtraBitfields() is true.
  //
  // * Optionally exactly one of:
  //   * an array of getNumExceptions() ExceptionType,
  //   * a single Expr *,
  //   * a pair of FunctionDecl *,
  //   * a single FunctionDecl *
  //   used to store information about the various types of exception
  //   specification. See getExceptionSpecSize for the details.
  //
  // * Optionally an array of getNumParams() ExtParameterInfo holding
  //   an ExtParameterInfo for each of the parameters. Present if and
  //   only if hasExtParameterInfos() is true.
  //
  // * Optionally a Qualifiers object to represent extra qualifiers that can't
  //   be represented by FunctionTypeBitfields.FastTypeQuals. Present if and only
  //   if hasExtQualifiers() is true.
  //
  // The optional FunctionTypeExtraBitfields has to be before the data
  // related to the exception specification since it contains the number
  // of exception types.
  //
  // We put the ExtParameterInfos last.  If all were equal, it would make
  // more sense to put these before the exception specification, because
  // it's much easier to skip past them compared to the elaborate switch
  // required to skip the exception specification.  However, all is not
  // equal; ExtParameterInfos are used to model very uncommon features,
  // and it's better not to burden the more common paths.
 
public:
  /// Holds information about the various types of exception specification.
  /// ExceptionSpecInfo is not stored as such in FunctionProtoType but is
  /// used to group together the various bits of information about the
  /// exception specification.
  struct ExceptionSpecInfo {
    /// The kind of exception specification this is.
    ExceptionSpecificationType Type = EST_None;
 
    /// Explicitly-specified list of exception types.
    ArrayRef<QualType> Exceptions;
 
    /// Noexcept expression, if this is a computed noexcept specification.
    Expr *NoexceptExpr = nullptr;
 
    /// The function whose exception specification this is, for
    /// EST_Unevaluated and EST_Uninstantiated.
    FunctionDecl *SourceDecl = nullptr;
 
    /// The function template whose exception specification this is instantiated
    /// from, for EST_Uninstantiated.
    FunctionDecl *SourceTemplate = nullptr;
 
    ExceptionSpecInfo() = default;
 
    ExceptionSpecInfo(ExceptionSpecificationType EST) : Type(EST) {}
  };
 
  /// Extra information about a function prototype. ExtProtoInfo is not
  /// stored as such in FunctionProtoType but is used to group together
  /// the various bits of extra information about a function prototype.
  struct ExtProtoInfo {
    FunctionType::ExtInfo ExtInfo;
    bool Variadic : 1;
    bool HasTrailingReturn : 1;
    Qualifiers TypeQuals;
    RefQualifierKind RefQualifier = RQ_None;
    ExceptionSpecInfo ExceptionSpec;
    const ExtParameterInfo *ExtParameterInfos = nullptr;
    SourceLocation EllipsisLoc;
 
    ExtProtoInfo() : Variadic(false), HasTrailingReturn(false) {}
 
    ExtProtoInfo(CallingConv CC)
        : ExtInfo(CC), Variadic(false), HasTrailingReturn(false) {}
 
    ExtProtoInfo withExceptionSpec(const ExceptionSpecInfo &ESI) {
      ExtProtoInfo Result(*this);
      Result.ExceptionSpec = ESI;
      return Result;
    }
  };
 
private:
  unsigned numTrailingObjects(OverloadToken<QualType>) const {
    return getNumParams();
  }
 
  unsigned numTrailingObjects(OverloadToken<SourceLocation>) const {
    return isVariadic();
  }
 
  unsigned numTrailingObjects(OverloadToken<FunctionTypeExtraBitfields>) const {
    return hasExtraBitfields();
  }
 
  unsigned numTrailingObjects(OverloadToken<ExceptionType>) const {
    return getExceptionSpecSize().NumExceptionType;
  }
 
  unsigned numTrailingObjects(OverloadToken<Expr *>) const {
    return getExceptionSpecSize().NumExprPtr;
  }
 
  unsigned numTrailingObjects(OverloadToken<FunctionDecl *>) const {
    return getExceptionSpecSize().NumFunctionDeclPtr;
  }
 
  unsigned numTrailingObjects(OverloadToken<ExtParameterInfo>) const {
    return hasExtParameterInfos() ? getNumParams() : 0;
  }
 
  /// Determine whether there are any argument types that
  /// contain an unexpanded parameter pack.
  static bool containsAnyUnexpandedParameterPack(const QualType *ArgArray,
                                                 unsigned numArgs) {
    for (unsigned Idx = 0; Idx < numArgs; ++Idx)
      if (ArgArray[Idx]->containsUnexpandedParameterPack())
        return true;
 
    return false;
  }
 
  FunctionProtoType(QualType result, ArrayRef<QualType> params,
                    QualType canonical, const ExtProtoInfo &epi);
 
  /// This struct is returned by getExceptionSpecSize and is used to
  /// translate an ExceptionSpecificationType to the number and kind
  /// of trailing objects related to the exception specification.
  struct ExceptionSpecSizeHolder {
    unsigned NumExceptionType;
    unsigned NumExprPtr;
    unsigned NumFunctionDeclPtr;
  };
 
  /// Return the number and kind of trailing objects
  /// related to the exception specification.
  static ExceptionSpecSizeHolder
  getExceptionSpecSize(ExceptionSpecificationType EST, unsigned NumExceptions) {
    switch (EST) {
    case EST_None:
    case EST_DynamicNone:
    case EST_MSAny:
    case EST_BasicNoexcept:
    case EST_Unparsed:
    case EST_NoThrow:
      return {0, 0, 0};
 
    case EST_Dynamic:
      return {NumExceptions, 0, 0};
 
    case EST_DependentNoexcept:
    case EST_NoexceptFalse:
    case EST_NoexceptTrue:
      return {0, 1, 0};
 
    case EST_Uninstantiated:
      return {0, 0, 2};
 
    case EST_Unevaluated:
      return {0, 0, 1};
    }
    llvm_unreachable("bad exception specification kind");
  }
 
  /// Return the number and kind of trailing objects
  /// related to the exception specification.
  ExceptionSpecSizeHolder getExceptionSpecSize() const {
    return getExceptionSpecSize(getExceptionSpecType(), getNumExceptions());
  }
 
  /// Whether the trailing FunctionTypeExtraBitfields is present.
  static bool hasExtraBitfields(ExceptionSpecificationType EST) {
    // If the exception spec type is EST_Dynamic then we have > 0 exception
    // types and the exact number is stored in FunctionTypeExtraBitfields.
    return EST == EST_Dynamic;
  }
 
  /// Whether the trailing FunctionTypeExtraBitfields is present.
  bool hasExtraBitfields() const {
    return hasExtraBitfields(getExceptionSpecType());
  }
 
  bool hasExtQualifiers() const {
    return FunctionTypeBits.HasExtQuals;
  }
 
public:
  unsigned getNumParams() const { return FunctionTypeBits.NumParams; }
 
  QualType getParamType(unsigned i) const {
    assert(i < getNumParams() && "invalid parameter index");
    return param_type_begin()[i];
  }
 
  ArrayRef<QualType> getParamTypes() const {
    return llvm::makeArrayRef(param_type_begin(), param_type_end());
  }
 
  ExtProtoInfo getExtProtoInfo() const {
    ExtProtoInfo EPI;
    EPI.ExtInfo = getExtInfo();
    EPI.Variadic = isVariadic();
    EPI.EllipsisLoc = getEllipsisLoc();
    EPI.HasTrailingReturn = hasTrailingReturn();
    EPI.ExceptionSpec = getExceptionSpecInfo();
    EPI.TypeQuals = getMethodQuals();
    EPI.RefQualifier = getRefQualifier();
    EPI.ExtParameterInfos = getExtParameterInfosOrNull();
    return EPI;
  }
 
  /// Get the kind of exception specification on this function.
  ExceptionSpecificationType getExceptionSpecType() const {
    return static_cast<ExceptionSpecificationType>(
        FunctionTypeBits.ExceptionSpecType);
  }
 
  /// Return whether this function has any kind of exception spec.
  bool hasExceptionSpec() const { return getExceptionSpecType() != EST_None; }
 
  /// Return whether this function has a dynamic (throw) exception spec.
  bool hasDynamicExceptionSpec() const {
    return isDynamicExceptionSpec(getExceptionSpecType());
  }
 
  /// Return whether this function has a noexcept exception spec.
  bool hasNoexceptExceptionSpec() const {
    return isNoexceptExceptionSpec(getExceptionSpecType());
  }
 
  /// Return whether this function has a dependent exception spec.
  bool hasDependentExceptionSpec() const;
 
  /// Return whether this function has an instantiation-dependent exception
  /// spec.
  bool hasInstantiationDependentExceptionSpec() const;
 
  /// Return all the available information about this type's exception spec.
  ExceptionSpecInfo getExceptionSpecInfo() const {
    ExceptionSpecInfo Result;
    Result.Type = getExceptionSpecType();
    if (Result.Type == EST_Dynamic) {
      Result.Exceptions = exceptions();
    } else if (isComputedNoexcept(Result.Type)) {
      Result.NoexceptExpr = getNoexceptExpr();
    } else if (Result.Type == EST_Uninstantiated) {
      Result.SourceDecl = getExceptionSpecDecl();
      Result.SourceTemplate = getExceptionSpecTemplate();
    } else if (Result.Type == EST_Unevaluated) {
      Result.SourceDecl = getExceptionSpecDecl();
    }
    return Result;
  }
 
  /// Return the number of types in the exception specification.
  unsigned getNumExceptions() const {
    return getExceptionSpecType() == EST_Dynamic
               ? getTrailingObjects<FunctionTypeExtraBitfields>()
                     ->NumExceptionType
               : 0;
  }
 
  /// Return the ith exception type, where 0 <= i < getNumExceptions().
  QualType getExceptionType(unsigned i) const {
    assert(i < getNumExceptions() && "Invalid exception number!");
    return exception_begin()[i];
  }
 
  /// Return the expression inside noexcept(expression), or a null pointer
  /// if there is none (because the exception spec is not of this form).
  Expr *getNoexceptExpr() const {
    if (!isComputedNoexcept(getExceptionSpecType()))
      return nullptr;
    return *getTrailingObjects<Expr *>();
  }
 
  /// If this function type has an exception specification which hasn't
  /// been determined yet (either because it has not been evaluated or because
  /// it has not been instantiated), this is the function whose exception
  /// specification is represented by this type.
  FunctionDecl *getExceptionSpecDecl() const {
    if (getExceptionSpecType() != EST_Uninstantiated &&
        getExceptionSpecType() != EST_Unevaluated)
      return nullptr;
    return getTrailingObjects<FunctionDecl *>()[0];
  }
 
  /// If this function type has an uninstantiated exception
  /// specification, this is the function whose exception specification
  /// should be instantiated to find the exception specification for
  /// this type.
  FunctionDecl *getExceptionSpecTemplate() const {
    if (getExceptionSpecType() != EST_Uninstantiated)
      return nullptr;
    return getTrailingObjects<FunctionDecl *>()[1];
  }
 
  /// Determine whether this function type has a non-throwing exception
  /// specification.
  CanThrowResult canThrow() const;
 
  /// Determine whether this function type has a non-throwing exception
  /// specification. If this depends on template arguments, returns
  /// \c ResultIfDependent.
  bool isNothrow(bool ResultIfDependent = false) const {
    return ResultIfDependent ? canThrow() != CT_Can : canThrow() == CT_Cannot;
  }
 
  /// Whether this function prototype is variadic.
  bool isVariadic() const { return FunctionTypeBits.Variadic; }
 
  SourceLocation getEllipsisLoc() const {
    return isVariadic() ? *getTrailingObjects<SourceLocation>()
                        : SourceLocation();
  }
 
  /// Determines whether this function prototype contains a
  /// parameter pack at the end.
  ///
  /// A function template whose last parameter is a parameter pack can be
  /// called with an arbitrary number of arguments, much like a variadic
  /// function.
  bool isTemplateVariadic() const;
 
  /// Whether this function prototype has a trailing return type.
  bool hasTrailingReturn() const { return FunctionTypeBits.HasTrailingReturn; }
 
  Qualifiers getMethodQuals() const {
    if (hasExtQualifiers())
      return *getTrailingObjects<Qualifiers>();
    else
      return getFastTypeQuals();
  }
 
  /// Retrieve the ref-qualifier associated with this function type.
  RefQualifierKind getRefQualifier() const {
    return static_cast<RefQualifierKind>(FunctionTypeBits.RefQualifier);
  }
 
  using param_type_iterator = const QualType *;
  using param_type_range = llvm::iterator_range<param_type_iterator>;
 
  param_type_range param_types() const {
    return param_type_range(param_type_begin(), param_type_end());
  }
 
  param_type_iterator param_type_begin() const {
    return getTrailingObjects<QualType>();
  }
 
  param_type_iterator param_type_end() const {
    return param_type_begin() + getNumParams();
  }
 
  using exception_iterator = const QualType *;
 
  ArrayRef<QualType> exceptions() const {
    return llvm::makeArrayRef(exception_begin(), exception_end());
  }
 
  exception_iterator exception_begin() const {
    return reinterpret_cast<exception_iterator>(
        getTrailingObjects<ExceptionType>());
  }
 
  exception_iterator exception_end() const {
    return exception_begin() + getNumExceptions();
  }
 
  /// Is there any interesting extra information for any of the parameters
  /// of this function type?
  bool hasExtParameterInfos() const {
    return FunctionTypeBits.HasExtParameterInfos;
  }
 
  ArrayRef<ExtParameterInfo> getExtParameterInfos() const {
    assert(hasExtParameterInfos());
    return ArrayRef<ExtParameterInfo>(getTrailingObjects<ExtParameterInfo>(),
                                      getNumParams());
  }
 
  /// Return a pointer to the beginning of the array of extra parameter
  /// information, if present, or else null if none of the parameters
  /// carry it.  This is equivalent to getExtProtoInfo().ExtParameterInfos.
  const ExtParameterInfo *getExtParameterInfosOrNull() const {
    if (!hasExtParameterInfos())
      return nullptr;
    return getTrailingObjects<ExtParameterInfo>();
  }
 
  ExtParameterInfo getExtParameterInfo(unsigned I) const {
    assert(I < getNumParams() && "parameter index out of range");
    if (hasExtParameterInfos())
      return getTrailingObjects<ExtParameterInfo>()[I];
    return ExtParameterInfo();
  }
 
  ParameterABI getParameterABI(unsigned I) const {
    assert(I < getNumParams() && "parameter index out of range");
    if (hasExtParameterInfos())
      return getTrailingObjects<ExtParameterInfo>()[I].getABI();
    return ParameterABI::Ordinary;
  }
 
  bool isParamConsumed(unsigned I) const {
    assert(I < getNumParams() && "parameter index out of range");
    if (hasExtParameterInfos())
      return getTrailingObjects<ExtParameterInfo>()[I].isConsumed();
    return false;
  }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  void printExceptionSpecification(raw_ostream &OS,
                                   const PrintingPolicy &Policy) const;
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == FunctionProto;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx);
  static void Profile(llvm::FoldingSetNodeID &ID, QualType Result,
                      param_type_iterator ArgTys, unsigned NumArgs,
                      const ExtProtoInfo &EPI, const ASTContext &Context,
                      bool Canonical);
};
 
/// Represents the dependent type named by a dependently-scoped
/// typename using declaration, e.g.
///   using typename Base<T>::foo;
///
/// Template instantiation turns these into the underlying type.
class UnresolvedUsingType : public Type {
  friend class ASTContext; // ASTContext creates these.
 
  UnresolvedUsingTypenameDecl *Decl;
 
  UnresolvedUsingType(const UnresolvedUsingTypenameDecl *D)
      : Type(UnresolvedUsing, QualType(),
             TypeDependence::DependentInstantiation),
        Decl(const_cast<UnresolvedUsingTypenameDecl *>(D)) {}
 
public:
  UnresolvedUsingTypenameDecl *getDecl() const { return Decl; }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == UnresolvedUsing;
  }
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    return Profile(ID, Decl);
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID,
                      UnresolvedUsingTypenameDecl *D) {
    ID.AddPointer(D);
  }
};
 
class UsingType : public Type, public llvm::FoldingSetNode {
  UsingShadowDecl *Found;
  friend class ASTContext; // ASTContext creates these.
 
  UsingType(const UsingShadowDecl *Found, QualType Underlying, QualType Canon);
 
public:
  UsingShadowDecl *getFoundDecl() const { return Found; }
  QualType getUnderlyingType() const;
 
  bool isSugared() const { return true; }
  QualType desugar() const { return getUnderlyingType(); }
 
  void Profile(llvm::FoldingSetNodeID &ID) { Profile(ID, Found); }
  static void Profile(llvm::FoldingSetNodeID &ID,
                      const UsingShadowDecl *Found) {
    ID.AddPointer(Found);
  }
  static bool classof(const Type *T) { return T->getTypeClass() == Using; }
};
 
class TypedefType : public Type {
  TypedefNameDecl *Decl;
 
private:
  friend class ASTContext; // ASTContext creates these.
 
  TypedefType(TypeClass tc, const TypedefNameDecl *D, QualType underlying,
              QualType can);
 
public:
  TypedefNameDecl *getDecl() const { return Decl; }
 
  bool isSugared() const { return true; }
  QualType desugar() const;
 
  static bool classof(const Type *T) { return T->getTypeClass() == Typedef; }
};
 
/// Sugar type that represents a type that was qualified by a qualifier written
/// as a macro invocation.
class MacroQualifiedType : public Type {
  friend class ASTContext; // ASTContext creates these.
 
  QualType UnderlyingTy;
  const IdentifierInfo *MacroII;
 
  MacroQualifiedType(QualType UnderlyingTy, QualType CanonTy,
                     const IdentifierInfo *MacroII)
      : Type(MacroQualified, CanonTy, UnderlyingTy->getDependence()),
        UnderlyingTy(UnderlyingTy), MacroII(MacroII) {
    assert(isa<AttributedType>(UnderlyingTy) &&
           "Expected a macro qualified type to only wrap attributed types.");
  }
 
public:
  const IdentifierInfo *getMacroIdentifier() const { return MacroII; }
  QualType getUnderlyingType() const { return UnderlyingTy; }
 
  /// Return this attributed type's modified type with no qualifiers attached to
  /// it.
  QualType getModifiedType() const;
 
  bool isSugared() const { return true; }
  QualType desugar() const;
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == MacroQualified;
  }
};
 
/// Represents a `typeof` (or __typeof__) expression (a GCC extension).
class TypeOfExprType : public Type {
  Expr *TOExpr;
 
protected:
  friend class ASTContext; // ASTContext creates these.
 
  TypeOfExprType(Expr *E, QualType can = QualType());
 
public:
  Expr *getUnderlyingExpr() const { return TOExpr; }
 
  /// Remove a single level of sugar.
  QualType desugar() const;
 
  /// Returns whether this type directly provides sugar.
  bool isSugared() const;
 
  static bool classof(const Type *T) { return T->getTypeClass() == TypeOfExpr; }
};
 
/// Internal representation of canonical, dependent
/// `typeof(expr)` types.
///
/// This class is used internally by the ASTContext to manage
/// canonical, dependent types, only. Clients will only see instances
/// of this class via TypeOfExprType nodes.
class DependentTypeOfExprType
  : public TypeOfExprType, public llvm::FoldingSetNode {
  const ASTContext &Context;
 
public:
  DependentTypeOfExprType(const ASTContext &Context, Expr *E)
      : TypeOfExprType(E), Context(Context) {}
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, Context, getUnderlyingExpr());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      Expr *E);
};
 
/// Represents `typeof(type)`, a GCC extension.
class TypeOfType : public Type {
  friend class ASTContext; // ASTContext creates these.
 
  QualType TOType;
 
  TypeOfType(QualType T, QualType can)
      : Type(TypeOf, can, T->getDependence()), TOType(T) {
    assert(!isa<TypedefType>(can) && "Invalid canonical type");
  }
 
public:
  QualType getUnderlyingType() const { return TOType; }
 
  /// Remove a single level of sugar.
  QualType desugar() const { return getUnderlyingType(); }
 
  /// Returns whether this type directly provides sugar.
  bool isSugared() const { return true; }
 
  static bool classof(const Type *T) { return T->getTypeClass() == TypeOf; }
};
 
/// Represents the type `decltype(expr)` (C++11).
class DecltypeType : public Type {
  Expr *E;
  QualType UnderlyingType;
 
protected:
  friend class ASTContext; // ASTContext creates these.
 
  DecltypeType(Expr *E, QualType underlyingType, QualType can = QualType());
 
public:
  Expr *getUnderlyingExpr() const { return E; }
  QualType getUnderlyingType() const { return UnderlyingType; }
 
  /// Remove a single level of sugar.
  QualType desugar() const;
 
  /// Returns whether this type directly provides sugar.
  bool isSugared() const;
 
  static bool classof(const Type *T) { return T->getTypeClass() == Decltype; }
};
 
/// Internal representation of canonical, dependent
/// decltype(expr) types.
///
/// This class is used internally by the ASTContext to manage
/// canonical, dependent types, only. Clients will only see instances
/// of this class via DecltypeType nodes.
class DependentDecltypeType : public DecltypeType, public llvm::FoldingSetNode {
  const ASTContext &Context;
 
public:
  DependentDecltypeType(const ASTContext &Context, Expr *E);
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, Context, getUnderlyingExpr());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      Expr *E);
};
 
/// A unary type transform, which is a type constructed from another.
class UnaryTransformType : public Type {
public:
  enum UTTKind {
    EnumUnderlyingType
  };
 
private:
  /// The untransformed type.
  QualType BaseType;
 
  /// The transformed type if not dependent, otherwise the same as BaseType.
  QualType UnderlyingType;
 
  UTTKind UKind;
 
protected:
  friend class ASTContext;
 
  UnaryTransformType(QualType BaseTy, QualType UnderlyingTy, UTTKind UKind,
                     QualType CanonicalTy);
 
public:
  bool isSugared() const { return !isDependentType(); }
  QualType desugar() const { return UnderlyingType; }
 
  QualType getUnderlyingType() const { return UnderlyingType; }
  QualType getBaseType() const { return BaseType; }
 
  UTTKind getUTTKind() const { return UKind; }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == UnaryTransform;
  }
};
 
/// Internal representation of canonical, dependent
/// __underlying_type(type) types.
///
/// This class is used internally by the ASTContext to manage
/// canonical, dependent types, only. Clients will only see instances
/// of this class via UnaryTransformType nodes.
class DependentUnaryTransformType : public UnaryTransformType,
                                    public llvm::FoldingSetNode {
public:
  DependentUnaryTransformType(const ASTContext &C, QualType BaseType,
                              UTTKind UKind);
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getBaseType(), getUTTKind());
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, QualType BaseType,
                      UTTKind UKind) {
    ID.AddPointer(BaseType.getAsOpaquePtr());
    ID.AddInteger((unsigned)UKind);
  }
};
 
class TagType : public Type {
  friend class ASTReader;
  template <class T> friend class serialization::AbstractTypeReader;
 
  /// Stores the TagDecl associated with this type. The decl may point to any
  /// TagDecl that declares the entity.
  TagDecl *decl;
 
protected:
  TagType(TypeClass TC, const TagDecl *D, QualType can);
 
public:
  TagDecl *getDecl() const;
 
  /// Determines whether this type is in the process of being defined.
  bool isBeingDefined() const;
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == Enum || T->getTypeClass() == Record;
  }
};
 
/// A helper class that allows the use of isa/cast/dyncast
/// to detect TagType objects of structs/unions/classes.
class RecordType : public TagType {
protected:
  friend class ASTContext; // ASTContext creates these.
 
  explicit RecordType(const RecordDecl *D)
      : TagType(Record, reinterpret_cast<const TagDecl*>(D), QualType()) {}
  explicit RecordType(TypeClass TC, RecordDecl *D)
      : TagType(TC, reinterpret_cast<const TagDecl*>(D), QualType()) {}
 
public:
  RecordDecl *getDecl() const {
    return reinterpret_cast<RecordDecl*>(TagType::getDecl());
  }
 
  /// Recursively check all fields in the record for const-ness. If any field
  /// is declared const, return true. Otherwise, return false.
  bool hasConstFields() const;
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) { return T->getTypeClass() == Record; }
};
 
/// A helper class that allows the use of isa/cast/dyncast
/// to detect TagType objects of enums.
class EnumType : public TagType {
  friend class ASTContext; // ASTContext creates these.
 
  explicit EnumType(const EnumDecl *D)
      : TagType(Enum, reinterpret_cast<const TagDecl*>(D), QualType()) {}
 
public:
  EnumDecl *getDecl() const {
    return reinterpret_cast<EnumDecl*>(TagType::getDecl());
  }
 
  bool isSugared() const { return false; }
  QualType desugar() const { return QualType(this, 0); }
 
  static bool classof(const Type *T) { return T->getTypeClass() == Enum; }
};
 
/// An attributed type is a type to which a type attribute has been applied.
///
/// The "modified type" is the fully-sugared type to which the attributed
/// type was applied; generally it is not canonically equivalent to the
/// attributed type. The "equivalent type" is the minimally-desugared type
/// which the type is canonically equivalent to.
///
/// For example, in the following attributed type:
///     int32_t __attribute__((vector_size(16)))
///   - the modified type is the TypedefType for int32_t
///   - the equivalent type is VectorType(16, int32_t)
///   - the canonical type is VectorType(16, int)
class AttributedType : public Type, public llvm::FoldingSetNode {
public:
  using Kind = attr::Kind;
 
private:
  friend class ASTContext; // ASTContext creates these
 
  QualType ModifiedType;
  QualType EquivalentType;
 
  AttributedType(QualType canon, attr::Kind attrKind, QualType modified,
                 QualType equivalent)
      : Type(Attributed, canon, equivalent->getDependence()),
        ModifiedType(modified), EquivalentType(equivalent) {
    AttributedTypeBits.AttrKind = attrKind;
  }
 
public:
  Kind getAttrKind() const {
    return static_cast<Kind>(AttributedTypeBits.AttrKind);
  }
 
  QualType getModifiedType() const { return ModifiedType; }
  QualType getEquivalentType() const { return EquivalentType; }
 
  bool isSugared() const { return true; }
  QualType desugar() const { return getEquivalentType(); }
 
  /// Does this attribute behave like a type qualifier?
  ///
  /// A type qualifier adjusts a type to provide specialized rules for
  /// a specific object, like the standard const and volatile qualifiers.
  /// This includes attributes controlling things like nullability,
  /// address spaces, and ARC ownership.  The value of the object is still
  /// largely described by the modified type.
  ///
  /// In contrast, many type attributes "rewrite" their modified type to
  /// produce a fundamentally different type, not necessarily related in any
  /// formalizable way to the original type.  For example, calling convention
  /// and vector attributes are not simple type qualifiers.
  ///
  /// Type qualifiers are often, but not always, reflected in the canonical
  /// type.
  bool isQualifier() const;
 
  bool isMSTypeSpec() const;
 
  bool isCallingConv() const;
 
  llvm::Optional<NullabilityKind> getImmediateNullability() const;
 
  /// Retrieve the attribute kind corresponding to the given
  /// nullability kind.
  static Kind getNullabilityAttrKind(NullabilityKind kind) {
    switch (kind) {
    case NullabilityKind::NonNull:
      return attr::TypeNonNull;
 
    case NullabilityKind::Nullable:
      return attr::TypeNullable;
 
    case NullabilityKind::NullableResult:
      return attr::TypeNullableResult;
 
    case NullabilityKind::Unspecified:
      return attr::TypeNullUnspecified;
    }
    llvm_unreachable("Unknown nullability kind.");
  }
 
  /// Strip off the top-level nullability annotation on the given
  /// type, if it's there.
  ///
  /// \param T The type to strip. If the type is exactly an
  /// AttributedType specifying nullability (without looking through
  /// type sugar), the nullability is returned and this type changed
  /// to the underlying modified type.
  ///
  /// \returns the top-level nullability, if present.
  static Optional<NullabilityKind> stripOuterNullability(QualType &T);
 
  void Profile(llvm::FoldingSetNodeID &ID) {
    Profile(ID, getAttrKind(), ModifiedType, EquivalentType);
  }
 
  static void Profile(llvm::FoldingSetNodeID &ID, Kind attrKind,
                      QualType modified, QualType equivalent) {
    ID.AddInteger(attrKind);
    ID.AddPointer(modified.getAsOpaquePtr());
    ID.AddPointer(equivalent.getAsOpaquePtr());
  }
 
  static bool classof(const Type *T) {
    return T->getTypeClass() == Attributed;
  }
};
 
class TemplateTypeParmType : public Type, public llvm::FoldingSetNode {
  friend class ASTContext; // ASTContext creates these
 
  // Helper data collector for canonical types.
  struct CanonicalTTPTInfo {
    unsigned Depth : 15;
    unsigned ParameterPack : 1;
    unsigned Index : 16;
  };
 
  union {
    // Info for the canonical type.