lib/AST/Type.cpp

//===- Type.cpp - Type representation and manipulation --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//  This file implements type-related functionality.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/Type.h"
#include "Linkage.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DependenceFlags.h"
#include "clang/AST/Expr.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/AST/NonTrivialTypeVisitor.h"
#include "clang/AST/PrettyPrinter.h"
#include "clang/AST/TemplateBase.h"
#include "clang/AST/TemplateName.h"
#include "clang/AST/TypeVisitor.h"
#include "clang/Basic/AddressSpaces.h"
#include "clang/Basic/ExceptionSpecificationType.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/Linkage.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Basic/TargetCXXABI.h"
#include "clang/Basic/TargetInfo.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/SmallVector.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstring>
#include <type_traits>

using namespace clang;

bool Qualifiers::isStrictSupersetOf(Qualifiers Other) const {
  return (*this != Other) &&
    // CVR qualifiers superset
    (((Mask & CVRMask) | (Other.Mask & CVRMask)) == (Mask & CVRMask)) &&
    // ObjC GC qualifiers superset
    ((getObjCGCAttr() == Other.getObjCGCAttr()) ||
     (hasObjCGCAttr() && !Other.hasObjCGCAttr())) &&
    // Address space superset.
    ((getAddressSpace() == Other.getAddressSpace()) ||
     (hasAddressSpace()&& !Other.hasAddressSpace())) &&
    // Lifetime qualifier superset.
    ((getObjCLifetime() == Other.getObjCLifetime()) ||
     (hasObjCLifetime() && !Other.hasObjCLifetime()));
}

const IdentifierInfo* QualType::getBaseTypeIdentifier() const {
  const Type* ty = getTypePtr();
  NamedDecl *ND = nullptr;
  if (ty->isPointerType() || ty->isReferenceType())
    return ty->getPointeeType().getBaseTypeIdentifier();
  else if (ty->isRecordType())
    ND = ty->castAs<RecordType>()->getDecl();
  else if (ty->isEnumeralType())
    ND = ty->castAs<EnumType>()->getDecl();
  else if (ty->getTypeClass() == Type::Typedef)
    ND = ty->castAs<TypedefType>()->getDecl();
  else if (ty->isArrayType())
    return ty->castAsArrayTypeUnsafe()->
        getElementType().getBaseTypeIdentifier();

  if (ND)
    return ND->getIdentifier();
  return nullptr;
}

bool QualType::mayBeDynamicClass() const {
  const auto *ClassDecl = getTypePtr()->getPointeeCXXRecordDecl();
  return ClassDecl && ClassDecl->mayBeDynamicClass();
}

bool QualType::mayBeNotDynamicClass() const {
  const auto *ClassDecl = getTypePtr()->getPointeeCXXRecordDecl();
  return !ClassDecl || ClassDecl->mayBeNonDynamicClass();
}

bool QualType::isConstant(QualType T, const ASTContext &Ctx) {
  if (T.isConstQualified())
    return true;

  if (const ArrayType *AT = Ctx.getAsArrayType(T))
    return AT->getElementType().isConstant(Ctx);

  return T.getAddressSpace() == LangAS::opencl_constant;
}

// C++ [temp.dep.type]p1:
//   A type is dependent if it is...
//     - an array type constructed from any dependent type or whose
//       size is specified by a constant expression that is
//       value-dependent,
ArrayType::ArrayType(TypeClass tc, QualType et, QualType can,
                     ArraySizeModifier sm, unsigned tq, const Expr *sz)
    // Note, we need to check for DependentSizedArrayType explicitly here
    // because we use a DependentSizedArrayType with no size expression as the
    // type of a dependent array of unknown bound with a dependent braced
    // initializer:
    //
    //   template<int ...N> int arr[] = {N...};
    : Type(tc, can,
           et->getDependence() |
               (sz ? toTypeDependence(
                         turnValueToTypeDependence(sz->getDependence()))
                   : TypeDependence::None) |
               (tc == VariableArray ? TypeDependence::VariablyModified
                                    : TypeDependence::None) |
               (tc == DependentSizedArray
                    ? TypeDependence::DependentInstantiation
                    : TypeDependence::None)),
      ElementType(et) {
  ArrayTypeBits.IndexTypeQuals = tq;
  ArrayTypeBits.SizeModifier = sm;
}

unsigned ConstantArrayType::getNumAddressingBits(const ASTContext &Context,
                                                 QualType ElementType,
                                               const llvm::APInt &NumElements) {
  uint64_t ElementSize = Context.getTypeSizeInChars(ElementType).getQuantity();

  // Fast path the common cases so we can avoid the conservative computation
  // below, which in common cases allocates "large" APSInt values, which are
  // slow.

  // If the element size is a power of 2, we can directly compute the additional
  // number of addressing bits beyond those required for the element count.
  if (llvm::isPowerOf2_64(ElementSize)) {
    return NumElements.getActiveBits() + llvm::Log2_64(ElementSize);
  }

  // If both the element count and element size fit in 32-bits, we can do the
  // computation directly in 64-bits.
  if ((ElementSize >> 32) == 0 && NumElements.getBitWidth() <= 64 &&
      (NumElements.getZExtValue() >> 32) == 0) {
    uint64_t TotalSize = NumElements.getZExtValue() * ElementSize;
    return 64 - llvm::countLeadingZeros(TotalSize);
  }

  // Otherwise, use APSInt to handle arbitrary sized values.
  llvm::APSInt SizeExtended(NumElements, true);
  unsigned SizeTypeBits = Context.getTypeSize(Context.getSizeType());
  SizeExtended = SizeExtended.extend(std::max(SizeTypeBits,
                                              SizeExtended.getBitWidth()) * 2);

  llvm::APSInt TotalSize(llvm::APInt(SizeExtended.getBitWidth(), ElementSize));
  TotalSize *= SizeExtended;

  return TotalSize.getActiveBits();
}

unsigned ConstantArrayType::getMaxSizeBits(const ASTContext &Context) {
  unsigned Bits = Context.getTypeSize(Context.getSizeType());

  // Limit the number of bits in size_t so that maximal bit size fits 64 bit
  // integer (see PR8256).  We can do this as currently there is no hardware
  // that supports full 64-bit virtual space.
  if (Bits > 61)
    Bits = 61;

  return Bits;
}

void ConstantArrayType::Profile(llvm::FoldingSetNodeID &ID,
                                const ASTContext &Context, QualType ET,
                                const llvm::APInt &ArraySize,
                                const Expr *SizeExpr, ArraySizeModifier SizeMod,
                                unsigned TypeQuals) {
  ID.AddPointer(ET.getAsOpaquePtr());
  ID.AddInteger(ArraySize.getZExtValue());
  ID.AddInteger(SizeMod);
  ID.AddInteger(TypeQuals);
  ID.AddBoolean(SizeExpr != 0);
  if (SizeExpr)
    SizeExpr->Profile(ID, Context, true);
}

DependentSizedArrayType::DependentSizedArrayType(const ASTContext &Context,
                                                 QualType et, QualType can,
                                                 Expr *e, ArraySizeModifier sm,
                                                 unsigned tq,
                                                 SourceRange brackets)
    : ArrayType(DependentSizedArray, et, can, sm, tq, e),
      Context(Context), SizeExpr((Stmt*) e), Brackets(brackets) {}

void DependentSizedArrayType::Profile(llvm::FoldingSetNodeID &ID,
                                      const ASTContext &Context,
                                      QualType ET,
                                      ArraySizeModifier SizeMod,
                                      unsigned TypeQuals,
                                      Expr *E) {
  ID.AddPointer(ET.getAsOpaquePtr());
  ID.AddInteger(SizeMod);
  ID.AddInteger(TypeQuals);
  E->Profile(ID, Context, true);
}

DependentVectorType::DependentVectorType(const ASTContext &Context,
                                         QualType ElementType,
                                         QualType CanonType, Expr *SizeExpr,
                                         SourceLocation Loc,
                                         VectorType::VectorKind VecKind)
    : Type(DependentVector, CanonType,
           TypeDependence::DependentInstantiation |
               ElementType->getDependence() |
               (SizeExpr ? toTypeDependence(SizeExpr->getDependence())
                         : TypeDependence::None)),
      Context(Context), ElementType(ElementType), SizeExpr(SizeExpr), Loc(Loc) {
  VectorTypeBits.VecKind = VecKind;
}

void DependentVectorType::Profile(llvm::FoldingSetNodeID &ID,
                                  const ASTContext &Context,
                                  QualType ElementType, const Expr *SizeExpr,
                                  VectorType::VectorKind VecKind) {
  ID.AddPointer(ElementType.getAsOpaquePtr());
  ID.AddInteger(VecKind);
  SizeExpr->Profile(ID, Context, true);
}

DependentSizedExtVectorType::DependentSizedExtVectorType(
    const ASTContext &Context, QualType ElementType, QualType can,
    Expr *SizeExpr, SourceLocation loc)
    : Type(DependentSizedExtVector, can,
           TypeDependence::DependentInstantiation |
               ElementType->getDependence() |
               (SizeExpr ? toTypeDependence(SizeExpr->getDependence())
                         : TypeDependence::None)),
      Context(Context), SizeExpr(SizeExpr), ElementType(ElementType), loc(loc) {
}

void
DependentSizedExtVectorType::Profile(llvm::FoldingSetNodeID &ID,
                                     const ASTContext &Context,
                                     QualType ElementType, Expr *SizeExpr) {
  ID.AddPointer(ElementType.getAsOpaquePtr());
  SizeExpr->Profile(ID, Context, true);
}

DependentAddressSpaceType::DependentAddressSpaceType(const ASTContext &Context,
                                                     QualType PointeeType,
                                                     QualType can,
                                                     Expr *AddrSpaceExpr,
                                                     SourceLocation loc)
    : Type(DependentAddressSpace, can,
           TypeDependence::DependentInstantiation |
               PointeeType->getDependence() |
               (AddrSpaceExpr ? toTypeDependence(AddrSpaceExpr->getDependence())
                              : TypeDependence::None)),
      Context(Context), AddrSpaceExpr(AddrSpaceExpr), PointeeType(PointeeType),
      loc(loc) {}

void DependentAddressSpaceType::Profile(llvm::FoldingSetNodeID &ID,
                                        const ASTContext &Context,
                                        QualType PointeeType,
                                        Expr *AddrSpaceExpr) {
  ID.AddPointer(PointeeType.getAsOpaquePtr());
  AddrSpaceExpr->Profile(ID, Context, true);
}

MatrixType::MatrixType(TypeClass tc, QualType matrixType, QualType canonType,
                       const Expr *RowExpr, const Expr *ColumnExpr)
    : Type(tc, canonType,
           (RowExpr ? (matrixType->getDependence() | TypeDependence::Dependent |
                       TypeDependence::Instantiation |
                       (matrixType->isVariablyModifiedType()
                            ? TypeDependence::VariablyModified
                            : TypeDependence::None) |
                       (matrixType->containsUnexpandedParameterPack() ||
                                (RowExpr &&
                                 RowExpr->containsUnexpandedParameterPack()) ||
                                (ColumnExpr &&
                                 ColumnExpr->containsUnexpandedParameterPack())
                            ? TypeDependence::UnexpandedPack
                            : TypeDependence::None))
                    : matrixType->getDependence())),
      ElementType(matrixType) {}

ConstantMatrixType::ConstantMatrixType(QualType matrixType, unsigned nRows,
                                       unsigned nColumns, QualType canonType)
    : ConstantMatrixType(ConstantMatrix, matrixType, nRows, nColumns,
                         canonType) {}

ConstantMatrixType::ConstantMatrixType(TypeClass tc, QualType matrixType,
                                       unsigned nRows, unsigned nColumns,
                                       QualType canonType)
    : MatrixType(tc, matrixType, canonType), NumRows(nRows),
      NumColumns(nColumns) {}

DependentSizedMatrixType::DependentSizedMatrixType(
    const ASTContext &CTX, QualType ElementType, QualType CanonicalType,
    Expr *RowExpr, Expr *ColumnExpr, SourceLocation loc)
    : MatrixType(DependentSizedMatrix, ElementType, CanonicalType, RowExpr,
                 ColumnExpr),
      Context(CTX), RowExpr(RowExpr), ColumnExpr(ColumnExpr), loc(loc) {}

void DependentSizedMatrixType::Profile(llvm::FoldingSetNodeID &ID,
                                       const ASTContext &CTX,
                                       QualType ElementType, Expr *RowExpr,
                                       Expr *ColumnExpr) {
  ID.AddPointer(ElementType.getAsOpaquePtr());
  RowExpr->Profile(ID, CTX, true);
  ColumnExpr->Profile(ID, CTX, true);
}

VectorType::VectorType(QualType vecType, unsigned nElements, QualType canonType,
                       VectorKind vecKind)
    : VectorType(Vector, vecType, nElements, canonType, vecKind) {}

VectorType::VectorType(TypeClass tc, QualType vecType, unsigned nElements,
                       QualType canonType, VectorKind vecKind)
    : Type(tc, canonType, vecType->getDependence()), ElementType(vecType) {
  VectorTypeBits.VecKind = vecKind;
  VectorTypeBits.NumElements = nElements;
}

ExtIntType::ExtIntType(bool IsUnsigned, unsigned NumBits)
    : Type(ExtInt, QualType{}, TypeDependence::None), IsUnsigned(IsUnsigned),
      NumBits(NumBits) {}

DependentExtIntType::DependentExtIntType(const ASTContext &Context,
                                         bool IsUnsigned, Expr *NumBitsExpr)
    : Type(DependentExtInt, QualType{},
           toTypeDependence(NumBitsExpr->getDependence())),
      Context(Context), ExprAndUnsigned(NumBitsExpr, IsUnsigned) {}

bool DependentExtIntType::isUnsigned() const {
  return ExprAndUnsigned.getInt();
}

clang::Expr *DependentExtIntType::getNumBitsExpr() const {
  return ExprAndUnsigned.getPointer();
}

void DependentExtIntType::Profile(llvm::FoldingSetNodeID &ID,
                                  const ASTContext &Context, bool IsUnsigned,
                                  Expr *NumBitsExpr) {
  ID.AddBoolean(IsUnsigned);
  NumBitsExpr->Profile(ID, Context, true);
}

/// getArrayElementTypeNoTypeQual - If this is an array type, return the
/// element type of the array, potentially with type qualifiers missing.
/// This method should never be used when type qualifiers are meaningful.
const Type *Type::getArrayElementTypeNoTypeQual() const {
  // If this is directly an array type, return it.
  if (const auto *ATy = dyn_cast<ArrayType>(this))
    return ATy->getElementType().getTypePtr();

  // If the canonical form of this type isn't the right kind, reject it.
  if (!isa<ArrayType>(CanonicalType))
    return nullptr;

  // If this is a typedef for an array type, strip the typedef off without
  // losing all typedef information.
  return cast<ArrayType>(getUnqualifiedDesugaredType())
    ->getElementType().getTypePtr();
}

/// getDesugaredType - 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.
QualType QualType::getDesugaredType(QualType T, const ASTContext &Context) {
  SplitQualType split = getSplitDesugaredType(T);
  return Context.getQualifiedType(split.Ty, split.Quals);
}

QualType QualType::getSingleStepDesugaredTypeImpl(QualType type,
                                                  const ASTContext &Context) {
  SplitQualType split = type.split();
  QualType desugar = split.Ty->getLocallyUnqualifiedSingleStepDesugaredType();
  return Context.getQualifiedType(desugar, split.Quals);
}

// Check that no type class is polymorphic. LLVM style RTTI should be used
// instead. If absolutely needed an exception can still be added here by
// defining the appropriate macro (but please don't do this).
#define TYPE(CLASS, BASE) \
  static_assert(!std::is_polymorphic<CLASS##Type>::value, \
                #CLASS "Type should not be polymorphic!");
#include "clang/AST/TypeNodes.inc"

// Check that no type class has a non-trival destructor. Types are
// allocated with the BumpPtrAllocator from ASTContext and therefore
// their destructor is not executed.
//
// FIXME: ConstantArrayType is not trivially destructible because of its
// APInt member. It should be replaced in favor of ASTContext allocation.
#define TYPE(CLASS, BASE)                                                      \
  static_assert(std::is_trivially_destructible<CLASS##Type>::value ||          \
                    std::is_same<CLASS##Type, ConstantArrayType>::value,       \
                #CLASS "Type should be trivially destructible!");
#include "clang/AST/TypeNodes.inc"

QualType Type::getLocallyUnqualifiedSingleStepDesugaredType() const {
  switch (getTypeClass()) {
#define ABSTRACT_TYPE(Class, Parent)
#define TYPE(Class, Parent) \
  case Type::Class: { \
    const auto *ty = cast<Class##Type>(this); \
    if (!ty->isSugared()) return QualType(ty, 0); \
    return ty->desugar(); \
  }
#include "clang/AST/TypeNodes.inc"
  }
  llvm_unreachable("bad type kind!");
}

SplitQualType QualType::getSplitDesugaredType(QualType T) {
  QualifierCollector Qs;

  QualType Cur = T;
  while (true) {
    const Type *CurTy = Qs.strip(Cur);
    switch (CurTy->getTypeClass()) {
#define ABSTRACT_TYPE(Class, Parent)
#define TYPE(Class, Parent) \
    case Type::Class: { \
      const auto *Ty = cast<Class##Type>(CurTy); \
      if (!Ty->isSugared()) \
        return SplitQualType(Ty, Qs); \
      Cur = Ty->desugar(); \
      break; \
    }
#include "clang/AST/TypeNodes.inc"
    }
  }
}

SplitQualType QualType::getSplitUnqualifiedTypeImpl(QualType type) {
  SplitQualType split = type.split();

  // All the qualifiers we've seen so far.
  Qualifiers quals = split.Quals;

  // The last type node we saw with any nodes inside it.
  const Type *lastTypeWithQuals = split.Ty;

  while (true) {
    QualType next;

    // Do a single-step desugar, aborting the loop if the type isn't
    // sugared.
    switch (split.Ty->getTypeClass()) {
#define ABSTRACT_TYPE(Class, Parent)
#define TYPE(Class, Parent) \
    case Type::Class: { \
      const auto *ty = cast<Class##Type>(split.Ty); \
      if (!ty->isSugared()) goto done; \
      next = ty->desugar(); \
      break; \
    }
#include "clang/AST/TypeNodes.inc"
    }

    // Otherwise, split the underlying type.  If that yields qualifiers,
    // update the information.
    split = next.split();
    if (!split.Quals.empty()) {
      lastTypeWithQuals = split.Ty;
      quals.addConsistentQualifiers(split.Quals);
    }
  }

 done:
  return SplitQualType(lastTypeWithQuals, quals);
}

QualType QualType::IgnoreParens(QualType T) {
  // FIXME: this seems inherently un-qualifiers-safe.
  while (const auto *PT = T->getAs<ParenType>())
    T = PT->getInnerType();
  return T;
}

/// This will check for a T (which should be a Type which can act as
/// sugar, such as a TypedefType) by removing any existing sugar until it
/// reaches a T or a non-sugared type.
template<typename T> static const T *getAsSugar(const Type *Cur) {
  while (true) {
    if (const auto *Sugar = dyn_cast<T>(Cur))
      return Sugar;
    switch (Cur->getTypeClass()) {
#define ABSTRACT_TYPE(Class, Parent)
#define TYPE(Class, Parent) \
    case Type::Class: { \
      const auto *Ty = cast<Class##Type>(Cur); \
      if (!Ty->isSugared()) return 0; \
      Cur = Ty->desugar().getTypePtr(); \
      break; \
    }
#include "clang/AST/TypeNodes.inc"
    }
  }
}

template <> const TypedefType *Type::getAs() const {
  return getAsSugar<TypedefType>(this);
}

template <> const TemplateSpecializationType *Type::getAs() const {
  return getAsSugar<TemplateSpecializationType>(this);
}

template <> const AttributedType *Type::getAs() const {
  return getAsSugar<AttributedType>(this);
}

/// getUnqualifiedDesugaredType - Pull any qualifiers and syntactic
/// sugar off the given type.  This should produce an object of the
/// same dynamic type as the canonical type.
const Type *Type::getUnqualifiedDesugaredType() const {
  const Type *Cur = this;

  while (true) {
    switch (Cur->getTypeClass()) {
#define ABSTRACT_TYPE(Class, Parent)
#define TYPE(Class, Parent) \
    case Class: { \
      const auto *Ty = cast<Class##Type>(Cur); \
      if (!Ty->isSugared()) return Cur; \
      Cur = Ty->desugar().getTypePtr(); \
      break; \
    }
#include "clang/AST/TypeNodes.inc"
    }
  }
}

bool Type::isClassType() const {
  if (const auto *RT = getAs<RecordType>())
    return RT->getDecl()->isClass();
  return false;
}

bool Type::isStructureType() const {
  if (const auto *RT = getAs<RecordType>())
    return RT->getDecl()->isStruct();
  return false;
}

bool Type::isObjCBoxableRecordType() const {
  if (const auto *RT = getAs<RecordType>())
    return RT->getDecl()->hasAttr<ObjCBoxableAttr>();
  return false;
}

bool Type::isInterfaceType() const {
  if (const auto *RT = getAs<RecordType>())
    return RT->getDecl()->isInterface();
  return false;
}

bool Type::isStructureOrClassType() const {
  if (const auto *RT = getAs<RecordType>()) {
    RecordDecl *RD = RT->getDecl();
    return RD->isStruct() || RD->isClass() || RD->isInterface();
  }
  return false;
}

bool Type::isVoidPointerType() const {
  if (const auto *PT = getAs<PointerType>())
    return PT->getPointeeType()->isVoidType();
  return false;
}

bool Type::isUnionType() const {
  if (const auto *RT = getAs<RecordType>())
    return RT->getDecl()->isUnion();
  return false;
}

bool Type::isComplexType() const {
  if (const auto *CT = dyn_cast<ComplexType>(CanonicalType))
    return CT->getElementType()->isFloatingType();
  return false;
}

bool Type::isComplexIntegerType() const {
  // Check for GCC complex integer extension.
  return getAsComplexIntegerType();
}

bool Type::isScopedEnumeralType() const {
  if (const auto *ET = getAs<EnumType>())
    return ET->getDecl()->isScoped();
  return false;
}

const ComplexType *Type::getAsComplexIntegerType() const {
  if (const auto *Complex = getAs<ComplexType>())
    if (Complex->getElementType()->isIntegerType())
      return Complex;
  return nullptr;
}

QualType Type::getPointeeType() const {
  if (const auto *PT = getAs<PointerType>())
    return PT->getPointeeType();
  if (const auto *OPT = getAs<ObjCObjectPointerType>())
    return OPT->getPointeeType();
  if (const auto *BPT = getAs<BlockPointerType>())
    return BPT->getPointeeType();
  if (const auto *RT = getAs<ReferenceType>())
    return RT->getPointeeType();
  if (const auto *MPT = getAs<MemberPointerType>())
    return MPT->getPointeeType();
  if (const auto *DT = getAs<DecayedType>())
    return DT->getPointeeType();
  return {};
}

const RecordType *Type::getAsStructureType() const {
  // If this is directly a structure type, return it.
  if (const auto *RT = dyn_cast<RecordType>(this)) {
    if (RT->getDecl()->isStruct())
      return RT;
  }

  // If the canonical form of this type isn't the right kind, reject it.
  if (const auto *RT = dyn_cast<RecordType>(CanonicalType)) {
    if (!RT->getDecl()->isStruct())
      return nullptr;

    // If this is a typedef for a structure type, strip the typedef off without
    // losing all typedef information.
    return cast<RecordType>(getUnqualifiedDesugaredType());
  }
  return nullptr;
}

const RecordType *Type::getAsUnionType() const {
  // If this is directly a union type, return it.
  if (const auto *RT = dyn_cast<RecordType>(this)) {
    if (RT->getDecl()->isUnion())
      return RT;
  }

  // If the canonical form of this type isn't the right kind, reject it.
  if (const auto *RT = dyn_cast<RecordType>(CanonicalType)) {
    if (!RT->getDecl()->isUnion())
      return nullptr;

    // If this is a typedef for a union type, strip the typedef off without
    // losing all typedef information.
    return cast<RecordType>(getUnqualifiedDesugaredType());
  }

  return nullptr;
}

bool Type::isObjCIdOrObjectKindOfType(const ASTContext &ctx,
                                      const ObjCObjectType *&bound) const {
  bound = nullptr;

  const auto *OPT = getAs<ObjCObjectPointerType>();
  if (!OPT)
    return false;

  // Easy case: id.
  if (OPT->isObjCIdType())
    return true;

  // If it's not a __kindof type, reject it now.
  if (!OPT->isKindOfType())
    return false;

  // If it's Class or qualified Class, it's not an object type.
  if (OPT->isObjCClassType() || OPT->isObjCQualifiedClassType())
    return false;

  // Figure out the type bound for the __kindof type.
  bound = OPT->getObjectType()->stripObjCKindOfTypeAndQuals(ctx)
            ->getAs<ObjCObjectType>();
  return true;
}

bool Type::isObjCClassOrClassKindOfType() const {
  const auto *OPT = getAs<ObjCObjectPointerType>();
  if (!OPT)
    return false;

  // Easy case: Class.
  if (OPT->isObjCClassType())
    return true;

  // If it's not a __kindof type, reject it now.
  if (!OPT->isKindOfType())
    return false;

  // If it's Class or qualified Class, it's a class __kindof type.
  return OPT->isObjCClassType() || OPT->isObjCQualifiedClassType();
}

ObjCTypeParamType::ObjCTypeParamType(const ObjCTypeParamDecl *D, QualType can,
                                     ArrayRef<ObjCProtocolDecl *> protocols)
    : Type(ObjCTypeParam, can,
           can->getDependence() & ~TypeDependence::UnexpandedPack),
      OTPDecl(const_cast<ObjCTypeParamDecl *>(D)) {
  initialize(protocols);
}

ObjCObjectType::ObjCObjectType(QualType Canonical, QualType Base,
                               ArrayRef<QualType> typeArgs,
                               ArrayRef<ObjCProtocolDecl *> protocols,
                               bool isKindOf)
    : Type(ObjCObject, Canonical, Base->getDependence()), BaseType(Base) {
  ObjCObjectTypeBits.IsKindOf = isKindOf;

  ObjCObjectTypeBits.NumTypeArgs = typeArgs.size();
  assert(getTypeArgsAsWritten().size() == typeArgs.size() &&
         "bitfield overflow in type argument count");
  if (!typeArgs.empty())
    memcpy(getTypeArgStorage(), typeArgs.data(),
           typeArgs.size() * sizeof(QualType));

  for (auto typeArg : typeArgs) {
    addDependence(typeArg->getDependence() & ~TypeDependence::VariablyModified);
  }
  // Initialize the protocol qualifiers. The protocol storage is known
  // after we set number of type arguments.
  initialize(protocols);
}

bool ObjCObjectType::isSpecialized() const {
  // If we have type arguments written here, the type is specialized.
  if (ObjCObjectTypeBits.NumTypeArgs > 0)
    return true;

  // Otherwise, check whether the base type is specialized.
  if (const auto objcObject = getBaseType()->getAs<ObjCObjectType>()) {
    // Terminate when we reach an interface type.
    if (isa<ObjCInterfaceType>(objcObject))
      return false;

    return objcObject->isSpecialized();
  }

  // Not specialized.
  return false;
}

ArrayRef<QualType> ObjCObjectType::getTypeArgs() const {
  // We have type arguments written on this type.
  if (isSpecializedAsWritten())
    return getTypeArgsAsWritten();

  // Look at the base type, which might have type arguments.
  if (const auto objcObject = getBaseType()->getAs<ObjCObjectType>()) {
    // Terminate when we reach an interface type.
    if (isa<ObjCInterfaceType>(objcObject))
      return {};

    return objcObject->getTypeArgs();
  }

  // No type arguments.
  return {};
}

bool ObjCObjectType::isKindOfType() const {
  if (isKindOfTypeAsWritten())
    return true;

  // Look at the base type, which might have type arguments.
  if (const auto objcObject = getBaseType()->getAs<ObjCObjectType>()) {
    // Terminate when we reach an interface type.
    if (isa<ObjCInterfaceType>(objcObject))
      return false;

    return objcObject->isKindOfType();
  }

  // Not a "__kindof" type.
  return false;
}

QualType ObjCObjectType::stripObjCKindOfTypeAndQuals(
           const ASTContext &ctx) const {
  if (!isKindOfType() && qual_empty())
    return QualType(this, 0);

  // Recursively strip __kindof.
  SplitQualType splitBaseType = getBaseType().split();
  QualType baseType(splitBaseType.Ty, 0);
  if (const auto *baseObj = splitBaseType.Ty->getAs<ObjCObjectType>())
    baseType = baseObj->stripObjCKindOfTypeAndQuals(ctx);

  return ctx.getObjCObjectType(ctx.getQualifiedType(baseType,
                                                    splitBaseType.Quals),
                               getTypeArgsAsWritten(),
                               /*protocols=*/{},
                               /*isKindOf=*/false);
}

const ObjCObjectPointerType *ObjCObjectPointerType::stripObjCKindOfTypeAndQuals(
                               const ASTContext &ctx) const {
  if (!isKindOfType() && qual_empty())
    return this;

  QualType obj = getObjectType()->stripObjCKindOfTypeAndQuals(ctx);
  return ctx.getObjCObjectPointerType(obj)->castAs<ObjCObjectPointerType>();
}

namespace {

/// Visitor used to perform a simple type transformation that does not change
/// the semantics of the type.
template <typename Derived>
struct SimpleTransformVisitor : public TypeVisitor<Derived, QualType> {
  ASTContext &Ctx;

  QualType recurse(QualType type) {
    // Split out the qualifiers from the type.
    SplitQualType splitType = type.split();

    // Visit the type itself.
    QualType result = static_cast<Derived *>(this)->Visit(splitType.Ty);
    if (result.isNull())
      return result;

    // Reconstruct the transformed type by applying the local qualifiers
    // from the split type.
    return Ctx.getQualifiedType(result, splitType.Quals);
  }

public:
  explicit SimpleTransformVisitor(ASTContext &ctx) : Ctx(ctx) {}

  // None of the clients of this transformation can occur where
  // there are dependent types, so skip dependent types.
#define TYPE(Class, Base)
#define DEPENDENT_TYPE(Class, Base) \
  QualType Visit##Class##Type(const Class##Type *T) { return QualType(T, 0); }
#include "clang/AST/TypeNodes.inc"

#define TRIVIAL_TYPE_CLASS(Class) \
  QualType Visit##Class##Type(const Class##Type *T) { return QualType(T, 0); }
#define SUGARED_TYPE_CLASS(Class) \
  QualType Visit##Class##Type(const Class##Type *T) { \
    if (!T->isSugared()) \
      return QualType(T, 0); \
    QualType desugaredType = recurse(T->desugar()); \
    if (desugaredType.isNull()) \
      return {}; \
    if (desugaredType.getAsOpaquePtr() == T->desugar().getAsOpaquePtr()) \
      return QualType(T, 0); \
    return desugaredType; \
  }

  TRIVIAL_TYPE_CLASS(Builtin)

  QualType VisitComplexType(const ComplexType *T) {
    QualType elementType = recurse(T->getElementType());
    if (elementType.isNull())
      return {};

    if (elementType.getAsOpaquePtr() == T->getElementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getComplexType(elementType);
  }

  QualType VisitPointerType(const PointerType *T) {
    QualType pointeeType = recurse(T->getPointeeType());
    if (pointeeType.isNull())
      return {};

    if (pointeeType.getAsOpaquePtr() == T->getPointeeType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getPointerType(pointeeType);
  }

  QualType VisitBlockPointerType(const BlockPointerType *T) {
    QualType pointeeType = recurse(T->getPointeeType());
    if (pointeeType.isNull())
      return {};

    if (pointeeType.getAsOpaquePtr() == T->getPointeeType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getBlockPointerType(pointeeType);
  }

  QualType VisitLValueReferenceType(const LValueReferenceType *T) {
    QualType pointeeType = recurse(T->getPointeeTypeAsWritten());
    if (pointeeType.isNull())
      return {};

    if (pointeeType.getAsOpaquePtr()
          == T->getPointeeTypeAsWritten().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getLValueReferenceType(pointeeType, T->isSpelledAsLValue());
  }

  QualType VisitRValueReferenceType(const RValueReferenceType *T) {
    QualType pointeeType = recurse(T->getPointeeTypeAsWritten());
    if (pointeeType.isNull())
      return {};

    if (pointeeType.getAsOpaquePtr()
          == T->getPointeeTypeAsWritten().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getRValueReferenceType(pointeeType);
  }

  QualType VisitMemberPointerType(const MemberPointerType *T) {
    QualType pointeeType = recurse(T->getPointeeType());
    if (pointeeType.isNull())
      return {};

    if (pointeeType.getAsOpaquePtr() == T->getPointeeType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getMemberPointerType(pointeeType, T->getClass());
  }

  QualType VisitConstantArrayType(const ConstantArrayType *T) {
    QualType elementType = recurse(T->getElementType());
    if (elementType.isNull())
      return {};

    if (elementType.getAsOpaquePtr() == T->getElementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getConstantArrayType(elementType, T->getSize(), T->getSizeExpr(),
                                    T->getSizeModifier(),
                                    T->getIndexTypeCVRQualifiers());
  }

  QualType VisitVariableArrayType(const VariableArrayType *T) {
    QualType elementType = recurse(T->getElementType());
    if (elementType.isNull())
      return {};

    if (elementType.getAsOpaquePtr() == T->getElementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getVariableArrayType(elementType, T->getSizeExpr(),
                                    T->getSizeModifier(),
                                    T->getIndexTypeCVRQualifiers(),
                                    T->getBracketsRange());
  }

  QualType VisitIncompleteArrayType(const IncompleteArrayType *T) {
    QualType elementType = recurse(T->getElementType());
    if (elementType.isNull())
      return {};

    if (elementType.getAsOpaquePtr() == T->getElementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getIncompleteArrayType(elementType, T->getSizeModifier(),
                                      T->getIndexTypeCVRQualifiers());
  }

  QualType VisitVectorType(const VectorType *T) {
    QualType elementType = recurse(T->getElementType());
    if (elementType.isNull())
      return {};

    if (elementType.getAsOpaquePtr() == T->getElementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getVectorType(elementType, T->getNumElements(),
                             T->getVectorKind());
  }

  QualType VisitExtVectorType(const ExtVectorType *T) {
    QualType elementType = recurse(T->getElementType());
    if (elementType.isNull())
      return {};

    if (elementType.getAsOpaquePtr() == T->getElementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getExtVectorType(elementType, T->getNumElements());
  }

  QualType VisitConstantMatrixType(const ConstantMatrixType *T) {
    QualType elementType = recurse(T->getElementType());
    if (elementType.isNull())
      return {};
    if (elementType.getAsOpaquePtr() == T->getElementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getConstantMatrixType(elementType, T->getNumRows(),
                                     T->getNumColumns());
  }

  QualType VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
    QualType returnType = recurse(T->getReturnType());
    if (returnType.isNull())
      return {};

    if (returnType.getAsOpaquePtr() == T->getReturnType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getFunctionNoProtoType(returnType, T->getExtInfo());
  }

  QualType VisitFunctionProtoType(const FunctionProtoType *T) {
    QualType returnType = recurse(T->getReturnType());
    if (returnType.isNull())
      return {};

    // Transform parameter types.
    SmallVector<QualType, 4> paramTypes;
    bool paramChanged = false;
    for (auto paramType : T->getParamTypes()) {
      QualType newParamType = recurse(paramType);
      if (newParamType.isNull())
        return {};

      if (newParamType.getAsOpaquePtr() != paramType.getAsOpaquePtr())
        paramChanged = true;

      paramTypes.push_back(newParamType);
    }

    // Transform extended info.
    FunctionProtoType::ExtProtoInfo info = T->getExtProtoInfo();
    bool exceptionChanged = false;
    if (info.ExceptionSpec.Type == EST_Dynamic) {
      SmallVector<QualType, 4> exceptionTypes;
      for (auto exceptionType : info.ExceptionSpec.Exceptions) {
        QualType newExceptionType = recurse(exceptionType);
        if (newExceptionType.isNull())
          return {};

        if (newExceptionType.getAsOpaquePtr() != exceptionType.getAsOpaquePtr())
          exceptionChanged = true;

        exceptionTypes.push_back(newExceptionType);
      }

      if (exceptionChanged) {
        info.ExceptionSpec.Exceptions =
            llvm::makeArrayRef(exceptionTypes).copy(Ctx);
      }
    }

    if (returnType.getAsOpaquePtr() == T->getReturnType().getAsOpaquePtr() &&
        !paramChanged && !exceptionChanged)
      return QualType(T, 0);

    return Ctx.getFunctionType(returnType, paramTypes, info);
  }

  QualType VisitParenType(const ParenType *T) {
    QualType innerType = recurse(T->getInnerType());
    if (innerType.isNull())
      return {};

    if (innerType.getAsOpaquePtr() == T->getInnerType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getParenType(innerType);
  }

  SUGARED_TYPE_CLASS(Typedef)
  SUGARED_TYPE_CLASS(ObjCTypeParam)
  SUGARED_TYPE_CLASS(MacroQualified)

  QualType VisitAdjustedType(const AdjustedType *T) {
    QualType originalType = recurse(T->getOriginalType());
    if (originalType.isNull())
      return {};

    QualType adjustedType = recurse(T->getAdjustedType());
    if (adjustedType.isNull())
      return {};

    if (originalType.getAsOpaquePtr()
          == T->getOriginalType().getAsOpaquePtr() &&
        adjustedType.getAsOpaquePtr() == T->getAdjustedType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getAdjustedType(originalType, adjustedType);
  }

  QualType VisitDecayedType(const DecayedType *T) {
    QualType originalType = recurse(T->getOriginalType());
    if (originalType.isNull())
      return {};

    if (originalType.getAsOpaquePtr()
          == T->getOriginalType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getDecayedType(originalType);
  }

  SUGARED_TYPE_CLASS(TypeOfExpr)
  SUGARED_TYPE_CLASS(TypeOf)
  SUGARED_TYPE_CLASS(Decltype)
  SUGARED_TYPE_CLASS(UnaryTransform)
  TRIVIAL_TYPE_CLASS(Record)
  TRIVIAL_TYPE_CLASS(Enum)

  // FIXME: Non-trivial to implement, but important for C++
  SUGARED_TYPE_CLASS(Elaborated)

  QualType VisitAttributedType(const AttributedType *T) {
    QualType modifiedType = recurse(T->getModifiedType());
    if (modifiedType.isNull())
      return {};

    QualType equivalentType = recurse(T->getEquivalentType());
    if (equivalentType.isNull())
      return {};

    if (modifiedType.getAsOpaquePtr()
          == T->getModifiedType().getAsOpaquePtr() &&
        equivalentType.getAsOpaquePtr()
          == T->getEquivalentType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getAttributedType(T->getAttrKind(), modifiedType,
                                 equivalentType);
  }

  QualType VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
    QualType replacementType = recurse(T->getReplacementType());
    if (replacementType.isNull())
      return {};

    if (replacementType.getAsOpaquePtr()
          == T->getReplacementType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getSubstTemplateTypeParmType(T->getReplacedParameter(),
                                            replacementType);
  }

  // FIXME: Non-trivial to implement, but important for C++
  SUGARED_TYPE_CLASS(TemplateSpecialization)

  QualType VisitAutoType(const AutoType *T) {
    if (!T->isDeduced())
      return QualType(T, 0);

    QualType deducedType = recurse(T->getDeducedType());
    if (deducedType.isNull())
      return {};

    if (deducedType.getAsOpaquePtr()
          == T->getDeducedType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getAutoType(deducedType, T->getKeyword(),
                           T->isDependentType(), /*IsPack=*/false,
                           T->getTypeConstraintConcept(),
                           T->getTypeConstraintArguments());
  }

  QualType VisitObjCObjectType(const ObjCObjectType *T) {
    QualType baseType = recurse(T->getBaseType());
    if (baseType.isNull())
      return {};

    // Transform type arguments.
    bool typeArgChanged = false;
    SmallVector<QualType, 4> typeArgs;
    for (auto typeArg : T->getTypeArgsAsWritten()) {
      QualType newTypeArg = recurse(typeArg);
      if (newTypeArg.isNull())
        return {};

      if (newTypeArg.getAsOpaquePtr() != typeArg.getAsOpaquePtr())
        typeArgChanged = true;

      typeArgs.push_back(newTypeArg);
    }

    if (baseType.getAsOpaquePtr() == T->getBaseType().getAsOpaquePtr() &&
        !typeArgChanged)
      return QualType(T, 0);

    return Ctx.getObjCObjectType(baseType, typeArgs,
                                 llvm::makeArrayRef(T->qual_begin(),
                                                    T->getNumProtocols()),
                                 T->isKindOfTypeAsWritten());
  }

  TRIVIAL_TYPE_CLASS(ObjCInterface)

  QualType VisitObjCObjectPointerType(const ObjCObjectPointerType *T) {
    QualType pointeeType = recurse(T->getPointeeType());
    if (pointeeType.isNull())
      return {};

    if (pointeeType.getAsOpaquePtr()
          == T->getPointeeType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getObjCObjectPointerType(pointeeType);
  }

  QualType VisitAtomicType(const AtomicType *T) {
    QualType valueType = recurse(T->getValueType());
    if (valueType.isNull())
      return {};

    if (valueType.getAsOpaquePtr()
          == T->getValueType().getAsOpaquePtr())
      return QualType(T, 0);

    return Ctx.getAtomicType(valueType);
  }

#undef TRIVIAL_TYPE_CLASS
#undef SUGARED_TYPE_CLASS
};

struct SubstObjCTypeArgsVisitor
    : public SimpleTransformVisitor<SubstObjCTypeArgsVisitor> {
  using BaseType = SimpleTransformVisitor<SubstObjCTypeArgsVisitor>;

  ArrayRef<QualType> TypeArgs;
  ObjCSubstitutionContext SubstContext;

  SubstObjCTypeArgsVisitor(ASTContext &ctx, ArrayRef<QualType> typeArgs,
                           ObjCSubstitutionContext context)
      : BaseType(ctx), TypeArgs(typeArgs), SubstContext(context) {}

  QualType VisitObjCTypeParamType(const ObjCTypeParamType *OTPTy) {
    // Replace an Objective-C type parameter reference with the corresponding
    // type argument.
    ObjCTypeParamDecl *typeParam = OTPTy->getDecl();
    // If we have type arguments, use them.
    if (!TypeArgs.empty()) {
      QualType argType = TypeArgs[typeParam->getIndex()];
      if (OTPTy->qual_empty())
        return argType;

      // Apply protocol lists if exists.
      bool hasError;
      SmallVector<ObjCProtocolDecl *, 8> protocolsVec;
      protocolsVec.append(OTPTy->qual_begin(), OTPTy->qual_end());
      ArrayRef<ObjCProtocolDecl *> protocolsToApply = protocolsVec;
      return Ctx.applyObjCProtocolQualifiers(
          argType, protocolsToApply, hasError, true/*allowOnPointerType*/);
    }

    switch (SubstContext) {
    case ObjCSubstitutionContext::Ordinary:
    case ObjCSubstitutionContext::Parameter:
    case ObjCSubstitutionContext::Superclass:
      // Substitute the bound.
      return typeParam->getUnderlyingType();

    case ObjCSubstitutionContext::Result:
    case ObjCSubstitutionContext::Property: {
      // Substitute the __kindof form of the underlying type.
      const auto *objPtr =
          typeParam->getUnderlyingType()->castAs<ObjCObjectPointerType>();

      // __kindof types, id, and Class don't need an additional
      // __kindof.
      if (objPtr->isKindOfType() || objPtr->isObjCIdOrClassType())
        return typeParam->getUnderlyingType();

      // Add __kindof.
      const auto *obj = objPtr->getObjectType();
      QualType resultTy = Ctx.getObjCObjectType(
          obj->getBaseType(), obj->getTypeArgsAsWritten(), obj->getProtocols(),
          /*isKindOf=*/true);

      // Rebuild object pointer type.
      return Ctx.getObjCObjectPointerType(resultTy);
    }
    }
    llvm_unreachable("Unexpected ObjCSubstitutionContext!");
  }

  QualType VisitFunctionType(const FunctionType *funcType) {
    // If we have a function type, update the substitution context
    // appropriately.

    //Substitute result type.
    QualType returnType = funcType->getReturnType().substObjCTypeArgs(
        Ctx, TypeArgs, ObjCSubstitutionContext::Result);
    if (returnType.isNull())
      return {};

    // Handle non-prototyped functions, which only substitute into the result
    // type.
    if (isa<FunctionNoProtoType>(funcType)) {
      // If the return type was unchanged, do nothing.
      if (returnType.getAsOpaquePtr() ==
          funcType->getReturnType().getAsOpaquePtr())
        return BaseType::VisitFunctionType(funcType);

      // Otherwise, build a new type.
      return Ctx.getFunctionNoProtoType(returnType, funcType->getExtInfo());
    }

    const auto *funcProtoType = cast<FunctionProtoType>(funcType);

    // Transform parameter types.
    SmallVector<QualType, 4> paramTypes;
    bool paramChanged = false;
    for (auto paramType : funcProtoType->getParamTypes()) {
      QualType newParamType = paramType.substObjCTypeArgs(
          Ctx, TypeArgs, ObjCSubstitutionContext::Parameter);
      if (newParamType.isNull())
        return {};

      if (newParamType.getAsOpaquePtr() != paramType.getAsOpaquePtr())
        paramChanged = true;

      paramTypes.push_back(newParamType);
    }

    // Transform extended info.
    FunctionProtoType::ExtProtoInfo info = funcProtoType->getExtProtoInfo();
    bool exceptionChanged = false;
    if (info.ExceptionSpec.Type == EST_Dynamic) {
      SmallVector<QualType, 4> exceptionTypes;
      for (auto exceptionType : info.ExceptionSpec.Exceptions) {
        QualType newExceptionType = exceptionType.substObjCTypeArgs(
            Ctx, TypeArgs, ObjCSubstitutionContext::Ordinary);
        if (newExceptionType.isNull())
          return {};

        if (newExceptionType.getAsOpaquePtr() != exceptionType.getAsOpaquePtr())
          exceptionChanged = true;

        exceptionTypes.push_back(newExceptionType);
      }

      if (exceptionChanged) {
        info.ExceptionSpec.Exceptions =
            llvm::makeArrayRef(exceptionTypes).copy(Ctx);
      }
    }

    if (returnType.getAsOpaquePtr() ==
            funcProtoType->getReturnType().getAsOpaquePtr() &&
        !paramChanged && !exceptionChanged)
      return BaseType::VisitFunctionType(funcType);

    return Ctx.getFunctionType(returnType, paramTypes, info);
  }

  QualType VisitObjCObjectType(const ObjCObjectType *objcObjectType) {
    // Substitute into the type arguments of a specialized Objective-C object
    // type.
    if (objcObjectType->isSpecializedAsWritten()) {
      SmallVector<QualType, 4> newTypeArgs;
      bool anyChanged = false;
      for (auto typeArg : objcObjectType->getTypeArgsAsWritten()) {
        QualType newTypeArg = typeArg.substObjCTypeArgs(
            Ctx, TypeArgs, ObjCSubstitutionContext::Ordinary);
        if (newTypeArg.isNull())
          return {};

        if (newTypeArg.getAsOpaquePtr() != typeArg.getAsOpaquePtr()) {
          // If we're substituting based on an unspecialized context type,
          // produce an unspecialized type.
          ArrayRef<ObjCProtocolDecl *> protocols(
              objcObjectType->qual_begin(), objcObjectType->getNumProtocols());
          if (TypeArgs.empty() &&
              SubstContext != ObjCSubstitutionContext::Superclass) {
            return Ctx.getObjCObjectType(
                objcObjectType->getBaseType(), {}, protocols,
                objcObjectType->isKindOfTypeAsWritten());
          }

          anyChanged = true;
        }

        newTypeArgs.push_back(newTypeArg);
      }

      if (anyChanged) {
        ArrayRef<ObjCProtocolDecl *> protocols(
            objcObjectType->qual_begin(), objcObjectType->getNumProtocols());
        return Ctx.getObjCObjectType(objcObjectType->getBaseType(), newTypeArgs,
                                     protocols,
                                     objcObjectType->isKindOfTypeAsWritten());
      }
    }

    return BaseType::VisitObjCObjectType(objcObjectType);
  }

  QualType VisitAttributedType(const AttributedType *attrType) {
    QualType newType = BaseType::VisitAttributedType(attrType);
    if (newType.isNull())
      return {};

    const auto *newAttrType = dyn_cast<AttributedType>(newType.getTypePtr());
    if (!newAttrType || newAttrType->getAttrKind() != attr::ObjCKindOf)
      return newType;

    // Find out if it's an Objective-C object or object pointer type;
    QualType newEquivType = newAttrType->getEquivalentType();
    const ObjCObjectPointerType *ptrType =
        newEquivType->getAs<ObjCObjectPointerType>();
    const ObjCObjectType *objType = ptrType
                                        ? ptrType->getObjectType()
                                        : newEquivType->getAs<ObjCObjectType>();
    if (!objType)
      return newType;

    // Rebuild the "equivalent" type, which pushes __kindof down into
    // the object type.
    newEquivType = Ctx.getObjCObjectType(
        objType->getBaseType(), objType->getTypeArgsAsWritten(),
        objType->getProtocols(),
        // There is no need to apply kindof on an unqualified id type.
        /*isKindOf=*/objType->isObjCUnqualifiedId() ? false : true);

    // If we started with an object pointer type, rebuild it.
    if (ptrType)
      newEquivType = Ctx.getObjCObjectPointerType(newEquivType);

    // Rebuild the attributed type.
    return Ctx.getAttributedType(newAttrType->getAttrKind(),
                                 newAttrType->getModifiedType(), newEquivType);
  }
};

struct StripObjCKindOfTypeVisitor
    : public SimpleTransformVisitor<StripObjCKindOfTypeVisitor> {
  using BaseType = SimpleTransformVisitor<StripObjCKindOfTypeVisitor>;

  explicit StripObjCKindOfTypeVisitor(ASTContext &ctx) : BaseType(ctx) {}

  QualType VisitObjCObjectType(const ObjCObjectType *objType) {
    if (!objType->isKindOfType())
      return BaseType::VisitObjCObjectType(objType);

    QualType baseType = objType->getBaseType().stripObjCKindOfType(Ctx);
    return Ctx.getObjCObjectType(baseType, objType->getTypeArgsAsWritten(),
                                 objType->getProtocols(),
                                 /*isKindOf=*/false);
  }
};

} // namespace

/// Substitute the given type arguments for Objective-C type
/// parameters within the given type, recursively.
QualType QualType::substObjCTypeArgs(ASTContext &ctx,
                                     ArrayRef<QualType> typeArgs,
                                     ObjCSubstitutionContext context) const {
  SubstObjCTypeArgsVisitor visitor(ctx, typeArgs, context);
  return visitor.recurse(*this);
}

QualType QualType::substObjCMemberType(QualType objectType,
                                       const DeclContext *dc,
                                       ObjCSubstitutionContext context) const {
  if (auto subs = objectType->getObjCSubstitutions(dc))
    return substObjCTypeArgs(dc->getParentASTContext(), *subs, context);

  return *this;
}

QualType QualType::stripObjCKindOfType(const ASTContext &constCtx) const {
  // FIXME: Because ASTContext::getAttributedType() is non-const.
  auto &ctx = const_cast<ASTContext &>(constCtx);
  StripObjCKindOfTypeVisitor visitor(ctx);
  return visitor.recurse(*this);
}

QualType QualType::getAtomicUnqualifiedType() const {
  if (const auto AT = getTypePtr()->getAs<AtomicType>())
    return AT->getValueType().getUnqualifiedType();
  return getUnqualifiedType();
}

Optional<ArrayRef<QualType>> Type::getObjCSubstitutions(
                               const DeclContext *dc) const {
  // Look through method scopes.
  if (const auto method = dyn_cast<ObjCMethodDecl>(dc))
    dc = method->getDeclContext();

  // Find the class or category in which the type we're substituting
  // was declared.
  const auto *dcClassDecl = dyn_cast<ObjCInterfaceDecl>(dc);
  const ObjCCategoryDecl *dcCategoryDecl = nullptr;
  ObjCTypeParamList *dcTypeParams = nullptr;
  if (dcClassDecl) {
    // If the class does not have any type parameters, there's no
    // substitution to do.
    dcTypeParams = dcClassDecl->getTypeParamList();
    if (!dcTypeParams)
      return None;
  } else {
    // If we are in neither a class nor a category, there's no
    // substitution to perform.
    dcCategoryDecl = dyn_cast<ObjCCategoryDecl>(dc);
    if (!dcCategoryDecl)
      return None;

    // If the category does not have any type parameters, there's no
    // substitution to do.
    dcTypeParams = dcCategoryDecl->getTypeParamList();
    if (!dcTypeParams)
      return None;

    dcClassDecl = dcCategoryDecl->getClassInterface();
    if (!dcClassDecl)
      return None;
  }
  assert(dcTypeParams && "No substitutions to perform");
  assert(dcClassDecl && "No class context");

  // Find the underlying object type.
  const ObjCObjectType *objectType;
  if (const auto *objectPointerType = getAs<ObjCObjectPointerType>()) {
    objectType = objectPointerType->getObjectType();
  } else if (getAs<BlockPointerType>()) {
    ASTContext &ctx = dc->getParentASTContext();
    objectType = ctx.getObjCObjectType(ctx.ObjCBuiltinIdTy, {}, {})
                   ->castAs<ObjCObjectType>();
  } else {
    objectType = getAs<ObjCObjectType>();
  }

  /// Extract the class from the receiver object type.
  ObjCInterfaceDecl *curClassDecl = objectType ? objectType->getInterface()
                                               : nullptr;
  if (!curClassDecl) {
    // If we don't have a context type (e.g., this is "id" or some
    // variant thereof), substitute the bounds.
    return llvm::ArrayRef<QualType>();
  }

  // Follow the superclass chain until we've mapped the receiver type
  // to the same class as the context.
  while (curClassDecl != dcClassDecl) {
    // Map to the superclass type.
    QualType superType = objectType->getSuperClassType();
    if (superType.isNull()) {
      objectType = nullptr;
      break;
    }

    objectType = superType->castAs<ObjCObjectType>();
    curClassDecl = objectType->getInterface();
  }

  // If we don't have a receiver type, or the receiver type does not
  // have type arguments, substitute in the defaults.
  if (!objectType || objectType->isUnspecialized()) {
    return llvm::ArrayRef<QualType>();
  }

  // The receiver type has the type arguments we want.
  return objectType->getTypeArgs();
}

bool Type::acceptsObjCTypeParams() const {
  if (auto *IfaceT = getAsObjCInterfaceType()) {
    if (auto *ID = IfaceT->getInterface()) {
      if (ID->getTypeParamList())
        return true;
    }
  }

  return false;
}

void ObjCObjectType::computeSuperClassTypeSlow() const {
  // Retrieve the class declaration for this type. If there isn't one
  // (e.g., this is some variant of "id" or "Class"), then there is no
  // superclass type.
  ObjCInterfaceDecl *classDecl = getInterface();
  if (!classDecl) {
    CachedSuperClassType.setInt(true);
    return;
  }

  // Extract the superclass type.
  const ObjCObjectType *superClassObjTy = classDecl->getSuperClassType();
  if (!superClassObjTy) {
    CachedSuperClassType.setInt(true);
    return;
  }

  ObjCInterfaceDecl *superClassDecl = superClassObjTy->getInterface();
  if (!superClassDecl) {
    CachedSuperClassType.setInt(true);
    return;
  }

  // If the superclass doesn't have type parameters, then there is no
  // substitution to perform.
  QualType superClassType(superClassObjTy, 0);
  ObjCTypeParamList *superClassTypeParams = superClassDecl->getTypeParamList();
  if (!superClassTypeParams) {
    CachedSuperClassType.setPointerAndInt(
      superClassType->castAs<ObjCObjectType>(), true);
    return;
  }

  // If the superclass reference is unspecialized, return it.
  if (superClassObjTy->isUnspecialized()) {
    CachedSuperClassType.setPointerAndInt(superClassObjTy, true);
    return;
  }

  // If the subclass is not parameterized, there aren't any type
  // parameters in the superclass reference to substitute.
  ObjCTypeParamList *typeParams = classDecl->getTypeParamList();
  if (!typeParams) {
    CachedSuperClassType.setPointerAndInt(
      superClassType->castAs<ObjCObjectType>(), true);
    return;
  }

  // If the subclass type isn't specialized, return the unspecialized
  // superclass.
  if (isUnspecialized()) {
    QualType unspecializedSuper
      = classDecl->getASTContext().getObjCInterfaceType(
          superClassObjTy->getInterface());
    CachedSuperClassType.setPointerAndInt(
      unspecializedSuper->castAs<ObjCObjectType>(),
      true);
    return;
  }

  // Substitute the provided type arguments into the superclass type.
  ArrayRef<QualType> typeArgs = getTypeArgs();
  assert(typeArgs.size() == typeParams->size());
  CachedSuperClassType.setPointerAndInt(
    superClassType.substObjCTypeArgs(classDecl->getASTContext(), typeArgs,
                                     ObjCSubstitutionContext::Superclass)
      ->castAs<ObjCObjectType>(),
    true);
}

const ObjCInterfaceType *ObjCObjectPointerType::getInterfaceType() const {
  if (auto interfaceDecl = getObjectType()->getInterface()) {
    return interfaceDecl->getASTContext().getObjCInterfaceType(interfaceDecl)
             ->castAs<ObjCInterfaceType>();
  }

  return nullptr;
}

QualType ObjCObjectPointerType::getSuperClassType() const {
  QualType superObjectType = getObjectType()->getSuperClassType();
  if (superObjectType.isNull())
    return superObjectType;

  ASTContext &ctx = getInterfaceDecl()->getASTContext();
  return ctx.getObjCObjectPointerType(superObjectType);
}

const ObjCObjectType *Type::getAsObjCQualifiedInterfaceType() const {
  // There is no sugar for ObjCObjectType's, just return the canonical
  // type pointer if it is the right class.  There is no typedef information to
  // return and these cannot be Address-space qualified.
  if (const auto *T = getAs<ObjCObjectType>())
    if (T->getNumProtocols() && T->getInterface())
      return T;
  return nullptr;
}

bool Type::isObjCQualifiedInterfaceType() const {
  return getAsObjCQualifiedInterfaceType() != nullptr;
}

const ObjCObjectPointerType *Type::getAsObjCQualifiedIdType() const {
  // There is no sugar for ObjCQualifiedIdType's, just return the canonical
  // type pointer if it is the right class.
  if (const auto *OPT = getAs<ObjCObjectPointerType>()) {
    if (OPT->isObjCQualifiedIdType())
      return OPT;
  }
  return nullptr;
}

const ObjCObjectPointerType *Type::getAsObjCQualifiedClassType() const {
  // There is no sugar for ObjCQualifiedClassType's, just return the canonical
  // type pointer if it is the right class.
  if (const auto *OPT = getAs<ObjCObjectPointerType>()) {
    if (OPT->isObjCQualifiedClassType())
      return OPT;
  }
  return nullptr;
}

const ObjCObjectType *Type::getAsObjCInterfaceType() const {
  if (const auto *OT = getAs<ObjCObjectType>()) {
    if (OT->getInterface())
      return OT;
  }
  return nullptr;
}

const ObjCObjectPointerType *Type::getAsObjCInterfacePointerType() const {
  if (const auto *OPT = getAs<ObjCObjectPointerType>()) {
    if (OPT->getInterfaceType())
      return OPT;
  }
  return nullptr;
}

const CXXRecordDecl *Type::getPointeeCXXRecordDecl() const {
  QualType PointeeType;
  if (const auto *PT = getAs<PointerType>())
    PointeeType = PT->getPointeeType();
  else if (const auto *RT = getAs<ReferenceType>())
    PointeeType = RT->getPointeeType();
  else
    return nullptr;

  if (const auto *RT = PointeeType->getAs<RecordType>())
    return dyn_cast<CXXRecordDecl>(RT->getDecl());

  return nullptr;
}

CXXRecordDecl *Type::getAsCXXRecordDecl() const {
  return dyn_cast_or_null<CXXRecordDecl>(getAsTagDecl());
}

RecordDecl *Type::getAsRecordDecl() const {
  return dyn_cast_or_null<RecordDecl>(getAsTagDecl());
}

TagDecl *Type::getAsTagDecl() const {
  if (const auto *TT = getAs<TagType>())
    return TT->getDecl();
  if (const auto *Injected = getAs<InjectedClassNameType>())
    return Injected->getDecl();

  return nullptr;
}

bool Type::hasAttr(attr::Kind AK) const {
  const Type *Cur = this;
  while (const auto *AT = Cur->getAs<AttributedType>()) {
    if (AT->getAttrKind() == AK)
      return true;
    Cur = AT->getEquivalentType().getTypePtr();
  }
  return false;
}

namespace {

  class GetContainedDeducedTypeVisitor :
    public TypeVisitor<GetContainedDeducedTypeVisitor, Type*> {
    bool Syntactic;

  public:
    GetContainedDeducedTypeVisitor(bool Syntactic = false)
        : Syntactic(Syntactic) {}

    using TypeVisitor<GetContainedDeducedTypeVisitor, Type*>::Visit;

    Type *Visit(QualType T) {
      if (T.isNull())
        return nullptr;
      return Visit(T.getTypePtr());
    }

    // The deduced type itself.
    Type *VisitDeducedType(const DeducedType *AT) {
      return const_cast<DeducedType*>(AT);
    }

    // Only these types can contain the desired 'auto' type.

    Type *VisitElaboratedType(const ElaboratedType *T) {
      return Visit(T->getNamedType());
    }

    Type *VisitPointerType(const PointerType *T) {
      return Visit(T->getPointeeType());
    }

    Type *VisitBlockPointerType(const BlockPointerType *T) {
      return Visit(T->getPointeeType());
    }

    Type *VisitReferenceType(const ReferenceType *T) {
      return Visit(T->getPointeeTypeAsWritten());
    }

    Type *VisitMemberPointerType(const MemberPointerType *T) {
      return Visit(T->getPointeeType());
    }

    Type *VisitArrayType(const ArrayType *T) {
      return Visit(T->getElementType());
    }

    Type *VisitDependentSizedExtVectorType(
      const DependentSizedExtVectorType *T) {
      return Visit(T->getElementType());
    }

    Type *VisitVectorType(const VectorType *T) {
      return Visit(T->getElementType());
    }

    Type *VisitDependentSizedMatrixType(const DependentSizedMatrixType *T) {
      return Visit(T->getElementType());
    }

    Type *VisitConstantMatrixType(const ConstantMatrixType *T) {
      return Visit(T->getElementType());
    }

    Type *VisitFunctionProtoType(const FunctionProtoType *T) {
      if (Syntactic && T->hasTrailingReturn())
        return const_cast<FunctionProtoType*>(T);
      return VisitFunctionType(T);
    }

    Type *VisitFunctionType(const FunctionType *T) {
      return Visit(T->getReturnType());
    }

    Type *VisitParenType(const ParenType *T) {
      return Visit(T->getInnerType());
    }

    Type *VisitAttributedType(const AttributedType *T) {
      return Visit(T->getModifiedType());
    }

    Type *VisitMacroQualifiedType(const MacroQualifiedType *T) {
      return Visit(T->getUnderlyingType());
    }

    Type *VisitAdjustedType(const AdjustedType *T) {
      return Visit(T->getOriginalType());
    }

    Type *VisitPackExpansionType(const PackExpansionType *T) {
      return Visit(T->getPattern());
    }
  };

} // namespace

DeducedType *Type::getContainedDeducedType() const {
  return cast_or_null<DeducedType>(
      GetContainedDeducedTypeVisitor().Visit(this));
}

bool Type::hasAutoForTrailingReturnType() const {
  return dyn_cast_or_null<FunctionType>(
      GetContainedDeducedTypeVisitor(true).Visit(this));
}

bool Type::hasIntegerRepresentation() const {
  if (const auto *VT = dyn_cast<VectorType>(CanonicalType))
    return VT->getElementType()->isIntegerType();
  else
    return isIntegerType();
}

/// Determine whether this type is an integral type.
///
/// This routine determines whether the given type is an integral type per
/// C++ [basic.fundamental]p7. Although the C standard does not define the
/// term "integral type", it has a similar term "integer type", and in C++
/// the two terms are equivalent. However, C's "integer type" includes
/// enumeration types, while C++'s "integer type" does not. The \c ASTContext
/// parameter is used to determine whether we should be following the C or
/// C++ rules when determining whether this type is an integral/integer type.
///
/// For cases where C permits "an integer type" and C++ permits "an integral
/// type", use this routine.
///
/// For cases where C permits "an integer type" and C++ permits "an integral
/// or enumeration type", use \c isIntegralOrEnumerationType() instead.
///
/// \param Ctx The context in which this type occurs.
///
/// \returns true if the type is considered an integral type, false otherwise.
bool Type::isIntegralType(const ASTContext &Ctx) const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() >= BuiltinType::Bool &&
           BT->getKind() <= BuiltinType::Int128;

  // Complete enum types are integral in C.
  if (!Ctx.getLangOpts().CPlusPlus)
    if (const auto *ET = dyn_cast<EnumType>(CanonicalType))
      return ET->getDecl()->isComplete();

  return isExtIntType();
}

bool Type::isIntegralOrUnscopedEnumerationType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() >= BuiltinType::Bool &&
           BT->getKind() <= BuiltinType::Int128;

  if (isExtIntType())
    return true;

  return isUnscopedEnumerationType();
}

bool Type::isUnscopedEnumerationType() const {
  if (const auto *ET = dyn_cast<EnumType>(CanonicalType))
    return !ET->getDecl()->isScoped();

  return false;
}

bool Type::isCharType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() == BuiltinType::Char_U ||
           BT->getKind() == BuiltinType::UChar ||
           BT->getKind() == BuiltinType::Char_S ||
           BT->getKind() == BuiltinType::SChar;
  return false;
}

bool Type::isWideCharType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() == BuiltinType::WChar_S ||
           BT->getKind() == BuiltinType::WChar_U;
  return false;
}

bool Type::isChar8Type() const {
  if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() == BuiltinType::Char8;
  return false;
}

bool Type::isChar16Type() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() == BuiltinType::Char16;
  return false;
}

bool Type::isChar32Type() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() == BuiltinType::Char32;
  return false;
}

/// Determine whether this type is any of the built-in character
/// types.
bool Type::isAnyCharacterType() const {
  const auto *BT = dyn_cast<BuiltinType>(CanonicalType);
  if (!BT) return false;
  switch (BT->getKind()) {
  default: return false;
  case BuiltinType::Char_U:
  case BuiltinType::UChar:
  case BuiltinType::WChar_U:
  case BuiltinType::Char8:
  case BuiltinType::Char16:
  case BuiltinType::Char32:
  case BuiltinType::Char_S:
  case BuiltinType::SChar:
  case BuiltinType::WChar_S:
    return true;
  }
}

/// isSignedIntegerType - Return true if this is an integer type that is
/// signed, according to C99 6.2.5p4 [char, signed char, short, int, long..],
/// an enum decl which has a signed representation
bool Type::isSignedIntegerType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
    return BT->getKind() >= BuiltinType::Char_S &&
           BT->getKind() <= BuiltinType::Int128;
  }

  if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType)) {
    // Incomplete enum types are not treated as integer types.
    // FIXME: In C++, enum types are never integer types.
    if (ET->getDecl()->isComplete() && !ET->getDecl()->isScoped())
      return ET->getDecl()->getIntegerType()->isSignedIntegerType();
  }

  if (const ExtIntType *IT = dyn_cast<ExtIntType>(CanonicalType))
    return IT->isSigned();

  return false;
}

bool Type::isSignedIntegerOrEnumerationType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
    return BT->getKind() >= BuiltinType::Char_S &&
           BT->getKind() <= BuiltinType::Int128;
  }

  if (const auto *ET = dyn_cast<EnumType>(CanonicalType)) {
    if (ET->getDecl()->isComplete())
      return ET->getDecl()->getIntegerType()->isSignedIntegerType();
  }

  if (const ExtIntType *IT = dyn_cast<ExtIntType>(CanonicalType))
    return IT->isSigned();


  return false;
}

bool Type::hasSignedIntegerRepresentation() const {
  if (const auto *VT = dyn_cast<VectorType>(CanonicalType))
    return VT->getElementType()->isSignedIntegerOrEnumerationType();
  else
    return isSignedIntegerOrEnumerationType();
}

/// isUnsignedIntegerType - Return true if this is an integer type that is
/// unsigned, according to C99 6.2.5p6 [which returns true for _Bool], an enum
/// decl which has an unsigned representation
bool Type::isUnsignedIntegerType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
    return BT->getKind() >= BuiltinType::Bool &&
           BT->getKind() <= BuiltinType::UInt128;
  }

  if (const auto *ET = dyn_cast<EnumType>(CanonicalType)) {
    // Incomplete enum types are not treated as integer types.
    // FIXME: In C++, enum types are never integer types.
    if (ET->getDecl()->isComplete() && !ET->getDecl()->isScoped())
      return ET->getDecl()->getIntegerType()->isUnsignedIntegerType();
  }

  if (const ExtIntType *IT = dyn_cast<ExtIntType>(CanonicalType))
    return IT->isUnsigned();

  return false;
}

bool Type::isUnsignedIntegerOrEnumerationType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
    return BT->getKind() >= BuiltinType::Bool &&
    BT->getKind() <= BuiltinType::UInt128;
  }

  if (const auto *ET = dyn_cast<EnumType>(CanonicalType)) {
    if (ET->getDecl()->isComplete())
      return ET->getDecl()->getIntegerType()->isUnsignedIntegerType();
  }

  if (const ExtIntType *IT = dyn_cast<ExtIntType>(CanonicalType))
    return IT->isUnsigned();

  return false;
}

bool Type::hasUnsignedIntegerRepresentation() const {
  if (const auto *VT = dyn_cast<VectorType>(CanonicalType))
    return VT->getElementType()->isUnsignedIntegerOrEnumerationType();
  else
    return isUnsignedIntegerOrEnumerationType();
}

bool Type::isFloatingType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() >= BuiltinType::Half &&
           BT->getKind() <= BuiltinType::Float128;
  if (const auto *CT = dyn_cast<ComplexType>(CanonicalType))
    return CT->getElementType()->isFloatingType();
  return false;
}

bool Type::hasFloatingRepresentation() const {
  if (const auto *VT = dyn_cast<VectorType>(CanonicalType))
    return VT->getElementType()->isFloatingType();
  else
    return isFloatingType();
}

bool Type::isRealFloatingType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->isFloatingPoint();
  return false;
}

bool Type::isRealType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() >= BuiltinType::Bool &&
           BT->getKind() <= BuiltinType::Float128;
  if (const auto *ET = dyn_cast<EnumType>(CanonicalType))
      return ET->getDecl()->isComplete() && !ET->getDecl()->isScoped();
  return isExtIntType();
}

bool Type::isArithmeticType() const {
  if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
    return BT->getKind() >= BuiltinType::Bool &&
           BT->getKind() <= BuiltinType::Float128 &&
           BT->getKind() != BuiltinType::BFloat16;
  if (const auto *ET = dyn_cast<EnumType>(CanonicalType))
    // GCC allows forward declaration of enum types (forbid by C99 6.7.2.3p2).
    // If a body isn't seen by the time we get here, return false.
    //
    // C++0x: Enumerations are not arithmetic types. For now, just return
    // false for scoped enumerations since that will disable any
    // unwanted implicit conversions.
    return !ET->getDecl()->isScoped() && ET->getDecl()->isComplete();
  return isa<ComplexType>(CanonicalType) || isExtIntType();
}

Type::ScalarTypeKind Type::getScalarTypeKind() const {
  assert(isScalarType());

  const Type *T = CanonicalType.getTypePtr();
  if (const auto *BT = dyn_cast<BuiltinType>(T)) {
    if (BT->getKind() == BuiltinType::Bool) return STK_Bool;
    if (BT->getKind() == BuiltinType::NullPtr) return STK_CPointer;
    if (BT->isInteger()) return STK_Integral;
    if (BT->isFloatingPoint()) return STK_Floating;
    if (BT->isFixedPointType()) return STK_FixedPoint;
    llvm_unreachable("unknown scalar builtin type");
  } else if (isa<PointerType>(T)) {
    return STK_CPointer;
  } else if (isa<BlockPointerType>(T)) {
    return STK_BlockPointer;
  } else if (isa<ObjCObjectPointerType>(T)) {
    return STK_ObjCObjectPointer;
  } else if (isa<MemberPointerType>(T)) {
    return STK_MemberPointer;
  } else if (isa<EnumType>(T)) {
    assert(cast<EnumType>(T)->getDecl()->isComplete());
    return STK_Integral;
  } else if (const auto *CT = dyn_cast<ComplexType>(T)) {
    if (CT->getElementType()->isRealFloatingType())
      return STK_FloatingComplex;
    return STK_IntegralComplex;
  } else if (isExtIntType()) {
    return STK_Integral;
  }

  llvm_unreachable("unknown scalar type");
}

/// Determines whether the type is a C++ aggregate type or C
/// aggregate or union type.
///
/// An aggregate type is an array or a class type (struct, union, or
/// class) that has no user-declared constructors, no private or
/// protected non-static data members, no base classes, and no virtual
/// functions (C++ [dcl.init.aggr]p1). The notion of an aggregate type
/// subsumes the notion of C aggregates (C99 6.2.5p21) because it also
/// includes union types.
bool Type::isAggregateType() const {
  if (const auto *Record = dyn_cast<RecordType>(CanonicalType)) {
    if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(Record->getDecl()))
      return ClassDecl->isAggregate();

    return true;
  }

  return isa<ArrayType>(CanonicalType);
}

/// isConstantSizeType - 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 or dependent types.
bool Type::isConstantSizeType() const {
  assert(!isIncompleteType() && "This doesn't make sense for incomplete types");
  assert(!isDependentType() && "This doesn't make sense for dependent types");
  // The VAT must have a size, as it is known to be complete.
  return !isa<VariableArrayType>(CanonicalType);
}

/// isIncompleteType - Return true if this is an incomplete type (C99 6.2.5p1)
/// - a type that can describe objects, but which lacks information needed to
/// determine its size.
bool Type::isIncompleteType(NamedDecl **Def) const {
  if (Def)
    *Def = nullptr;

  switch (CanonicalType->getTypeClass()) {
  default: return false;
  case Builtin:
    // Void is the only incomplete builtin type.  Per C99 6.2.5p19, it can never
    // be completed.
    return isVoidType();
  case Enum: {
    EnumDecl *EnumD = cast<EnumType>(CanonicalType)->getDecl();
    if (Def)
      *Def = EnumD;
    return !EnumD->isComplete();
  }
  case Record: {
    // A tagged type (struct/union/enum/class) is incomplete if the decl is a
    // forward declaration, but not a full definition (C99 6.2.5p22).
    RecordDecl *Rec = cast<RecordType>(CanonicalType)->getDecl();
    if (Def)
      *Def = Rec;
    return !Rec->isCompleteDefinition();
  }
  case ConstantArray:
    // An array is incomplete if its element type is incomplete
    // (C++ [dcl.array]p1).
    // We don't handle variable arrays (they're not allowed in C++) or
    // dependent-sized arrays (dependent types are never treated as incomplete).
    return cast<ArrayType>(CanonicalType)->getElementType()
             ->isIncompleteType(Def);
  case IncompleteArray:
    // An array of unknown size is an incomplete type (C99 6.2.5p22).
    return true;
  case MemberPointer: {
    // Member pointers in the MS ABI have special behavior in
    // RequireCompleteType: they attach a MSInheritanceAttr to the CXXRecordDecl
    // to indicate which inheritance model to use.
    auto *MPTy = cast<MemberPointerType>(CanonicalType);
    const Type *ClassTy = MPTy->getClass();
    // Member pointers with dependent class types don't get special treatment.
    if (ClassTy->isDependentType())
      return false;
    const CXXRecordDecl *RD = ClassTy->getAsCXXRecordDecl();
    ASTContext &Context = RD->getASTContext();
    // Member pointers not in the MS ABI don't get special treatment.
    if (!Context.getTargetInfo().getCXXABI().isMicrosoft())
      return false;
    // The inheritance attribute might only be present on the most recent
    // CXXRecordDecl, use that one.
    RD = RD->getMostRecentNonInjectedDecl();
    // Nothing interesting to do if the inheritance attribute is already set.
    if (RD->hasAttr<MSInheritanceAttr>())
      return false;
    return true;
  }
  case ObjCObject:
    return cast<ObjCObjectType>(CanonicalType)->getBaseType()
             ->isIncompleteType(Def);
  case ObjCInterface: {
    // ObjC interfaces are incomplete if they are @class, not @interface.
    ObjCInterfaceDecl *Interface
      = cast<ObjCInterfaceType>(CanonicalType)->getDecl();
    if (Def)
      *Def = Interface;
    return !Interface->hasDefinition();
  }
  }
}

bool Type::isSizelessBuiltinType() const {
  if (const BuiltinType *BT = getAs<BuiltinType>()) {
    switch (BT->getKind()) {
      // SVE Types
#define SVE_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
#include "clang/Basic/AArch64SVEACLETypes.def"
      return true;
    default:
      return false;
    }
  }
  return false;
}

bool Type::isSizelessType() const { return isSizelessBuiltinType(); }

bool Type::isVLSTBuiltinType() const {
  if (const BuiltinType *BT = getAs<BuiltinType>()) {
    switch (BT->getKind()) {
    case BuiltinType::SveInt8:
    case BuiltinType::SveInt16:
    case BuiltinType::SveInt32:
    case BuiltinType::SveInt64:
    case BuiltinType::SveUint8:
    case BuiltinType::SveUint16:
    case BuiltinType::SveUint32:
    case BuiltinType::SveUint64:
    case BuiltinType::SveFloat16:
    case BuiltinType::SveFloat32:
    case BuiltinType::SveFloat64:
    case BuiltinType::SveBFloat16:
    case BuiltinType::SveBool:
      return true;
    default:
      return false;
    }
  }
  return false;
}

bool Type::isVLST() const {
  if (!isVLSTBuiltinType())
    return false;

  return hasAttr(attr::ArmSveVectorBits);
}

bool QualType::isPODType(const ASTContext &Context) const {
  // C++11 has a more relaxed definition of POD.
  if (Context.getLangOpts().CPlusPlus11)
    return isCXX11PODType(Context);

  return isCXX98PODType(Context);
}

bool QualType::isCXX98PODType(const ASTContext &Context) const {
  // The compiler shouldn't query this for incomplete types, but the user might.
  // We return false for that case. Except for incomplete arrays of PODs, which
  // are PODs according to the standard.
  if (isNull())
    return false;

  if ((*this)->isIncompleteArrayType())
    return Context.getBaseElementType(*this).isCXX98PODType(Context);

  if ((*this)->isIncompleteType())
    return false;

  if (hasNonTrivialObjCLifetime())
    return false;

  QualType CanonicalType = getTypePtr()->CanonicalType;
  switch (CanonicalType->getTypeClass()) {
    // Everything not explicitly mentioned is not POD.
  default: return false;
  case Type::VariableArray:
  case Type::ConstantArray:
    // IncompleteArray is handled above.
    return Context.getBaseElementType(*this).isCXX98PODType(Context);

  case Type::ObjCObjectPointer:
  case Type::BlockPointer:
  case Type::Builtin:
  case Type::Complex:
  case Type::Pointer:
  case Type::MemberPointer:
  case Type::Vector:
  case Type::ExtVector:
  case Type::ExtInt:
    return true;

  case Type::Enum:
    return true;

  case Type::Record:
    if (const auto *ClassDecl =
            dyn_cast<CXXRecordDecl>(cast<RecordType>(CanonicalType)->getDecl()))
      return ClassDecl->isPOD();

    // C struct/union is POD.
    return true;
  }
}

bool QualType::isTrivialType(const ASTContext &Context) const {
  // The compiler shouldn't query this for incomplete types, but the user might.
  // We return false for that case. Except for incomplete arrays of PODs, which
  // are PODs according to the standard.
  if (isNull())
    return false;

  if ((*this)->isArrayType())
    return Context.getBaseElementType(*this).isTrivialType(Context);

  if ((*this)->isSizelessBuiltinType())
    return true;

  // Return false for incomplete types after skipping any incomplete array
  // types which are expressly allowed by the standard and thus our API.
  if ((*this)->isIncompleteType())
    return false;

  if (hasNonTrivialObjCLifetime())
    return false;

  QualType CanonicalType = getTypePtr()->CanonicalType;
  if (CanonicalType->isDependentType())
    return false;

  // C++0x [basic.types]p9:
  //   Scalar types, trivial class types, arrays of such types, and
  //   cv-qualified versions of these types are collectively called trivial
  //   types.

  // As an extension, Clang treats vector types as Scalar types.
  if (CanonicalType->isScalarType() || CanonicalType->isVectorType())
    return true;
  if (const auto *RT = CanonicalType->getAs<RecordType>()) {
    if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
      // C++11 [class]p6:
      //   A trivial class is a class that has a default constructor,
      //   has no non-trivial default constructors, and is trivially
      //   copyable.
      return ClassDecl->hasDefaultConstructor() &&
             !ClassDecl->hasNonTrivialDefaultConstructor() &&
             ClassDecl->isTriviallyCopyable();
    }

    return true;
  }

  // No other types can match.
  return false;
}

bool QualType::isTriviallyCopyableType(const ASTContext &Context) const {
  if ((*this)->isArrayType())
    return Context.getBaseElementType(*this).isTriviallyCopyableType(Context);

  if (hasNonTrivialObjCLifetime())
    return false;

  // C++11 [basic.types]p9 - See Core 2094
  //   Scalar types, trivially copyable class types, arrays of such types, and
  //   cv-qualified versions of these types are collectively
  //   called trivially copyable types.

  QualType CanonicalType = getCanonicalType();
  if (CanonicalType->isDependentType())
    return false;

  if (CanonicalType->isSizelessBuiltinType())
    return true;

  // Return false for incomplete types after skipping any incomplete array types
  // which are expressly allowed by the standard and thus our API.
  if (CanonicalType->isIncompleteType())
    return false;

  // As an extension, Clang treats vector types as Scalar types.
  if (CanonicalType->isScalarType() || CanonicalType->isVectorType())
    return true;

  if (const auto *RT = CanonicalType->getAs<RecordType>()) {
    if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
      if (!ClassDecl->isTriviallyCopyable()) return false;
    }

    return true;
  }

  // No other types can match.
  return false;
}

bool QualType::isNonWeakInMRRWithObjCWeak(const ASTContext &Context) const {
  return !Context.getLangOpts().ObjCAutoRefCount &&
         Context.getLangOpts().ObjCWeak &&
         getObjCLifetime() != Qualifiers::OCL_Weak;
}

bool QualType::hasNonTrivialToPrimitiveDefaultInitializeCUnion(const RecordDecl *RD) {
  return RD->hasNonTrivialToPrimitiveDefaultInitializeCUnion();
}

bool QualType::hasNonTrivialToPrimitiveDestructCUnion(const RecordDecl *RD) {
  return RD->hasNonTrivialToPrimitiveDestructCUnion();
}

bool QualType::hasNonTrivialToPrimitiveCopyCUnion(const RecordDecl *RD) {
  return RD->hasNonTrivialToPrimitiveCopyCUnion();
}

QualType::PrimitiveDefaultInitializeKind
QualType::isNonTrivialToPrimitiveDefaultInitialize() const {
  if (const auto *RT =
          getTypePtr()->getBaseElementTypeUnsafe()->getAs<RecordType>())
    if (RT->getDecl()->isNonTrivialToPrimitiveDefaultInitialize())
      return PDIK_Struct;

  switch (getQualifiers().getObjCLifetime()) {
  case Qualifiers::OCL_Strong:
    return PDIK_ARCStrong;
  case Qualifiers::OCL_Weak:
    return PDIK_ARCWeak;
  default:
    return PDIK_Trivial;
  }
}

QualType::PrimitiveCopyKind QualType::isNonTrivialToPrimitiveCopy() const {
  if (const auto *RT =
          getTypePtr()->getBaseElementTypeUnsafe()->getAs<RecordType>())
    if (RT->getDecl()->isNonTrivialToPrimitiveCopy())
      return PCK_Struct;

  Qualifiers Qs = getQualifiers();
  switch (Qs.getObjCLifetime()) {
  case Qualifiers::OCL_Strong:
    return PCK_ARCStrong;
  case Qualifiers::OCL_Weak:
    return PCK_ARCWeak;
  default:
    return Qs.hasVolatile() ? PCK_VolatileTrivial : PCK_Trivial;
  }
}

QualType::PrimitiveCopyKind
QualType::isNonTrivialToPrimitiveDestructiveMove() const {
  return isNonTrivialToPrimitiveCopy();
}

bool Type::isLiteralType(const ASTContext &Ctx) const {
  if (isDependentType())
    return false;

  // C++1y [basic.types]p10:
  //   A type is a literal type if it is:
  //   -- cv void; or
  if (Ctx.getLangOpts().CPlusPlus14 && isVoidType())
    return true;

  // C++11 [basic.types]p10:
  //   A type is a literal type if it is:
  //   [...]
  //   -- an array of literal type other than an array of runtime bound; or
  if (isVariableArrayType())
    return false;
  const Type *BaseTy = getBaseElementTypeUnsafe();
  assert(BaseTy && "NULL element type");

  // Return false for incomplete types after skipping any incomplete array
  // types; those are expressly allowed by the standard and thus our API.
  if (BaseTy->isIncompleteType())
    return false;

  // C++11 [basic.types]p10:
  //   A type is a literal type if it is:
  //    -- a scalar type; or
  // As an extension, Clang treats vector types and complex types as
  // literal types.
  if (BaseTy->isScalarType() || BaseTy->isVectorType() ||
      BaseTy->isAnyComplexType())
    return true;
  //    -- a reference type; or
  if (BaseTy->isReferenceType())
    return true;
  //    -- a class type that has all of the following properties:
  if (const auto *RT = BaseTy->getAs<RecordType>()) {
    //    -- a trivial destructor,
    //    -- every constructor call and full-expression in the
    //       brace-or-equal-initializers for non-static data members (if any)
    //       is a constant expression,
    //    -- it is an aggregate type or has at least one constexpr
    //       constructor or constructor template that is not a copy or move
    //       constructor, and
    //    -- all non-static data members and base classes of literal types
    //
    // We resolve DR1361 by ignoring the second bullet.
    if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl()))
      return ClassDecl->isLiteral();

    return true;
  }

  // We treat _Atomic T as a literal type if T is a literal type.
  if (const auto *AT = BaseTy->getAs<AtomicType>())
    return AT->getValueType()->isLiteralType(Ctx);

  // If this type hasn't been deduced yet, then conservatively assume that
  // it'll work out to be a literal type.
  if (isa<AutoType>(BaseTy->getCanonicalTypeInternal()))
    return true;

  return false;
}

bool Type::isStandardLayoutType() const {
  if (isDependentType())
    return false;

  // C++0x [basic.types]p9:
  //   Scalar types, standard-layout class types, arrays of such types, and
  //   cv-qualified versions of these types are collectively called
  //   standard-layout types.
  const Type *BaseTy = getBaseElementTypeUnsafe();
  assert(BaseTy && "NULL element type");

  // Return false for incomplete types after skipping any incomplete array
  // types which are expressly allowed by the standard and thus our API.
  if (BaseTy->isIncompleteType())
    return false;

  // As an extension, Clang treats vector types as Scalar types.
  if (BaseTy->isScalarType() || BaseTy->isVectorType()) return true;
  if (const auto *RT = BaseTy->getAs<RecordType>()) {
    if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl()))
      if (!ClassDecl->isStandardLayout())
        return false;

    // Default to 'true' for non-C++ class types.
    // FIXME: This is a bit dubious, but plain C structs should trivially meet
    // all the requirements of standard layout classes.
    return true;
  }

  // No other types can match.
  return false;
}

// This is effectively the intersection of isTrivialType and
// isStandardLayoutType. We implement it directly to avoid redundant
// conversions from a type to a CXXRecordDecl.
bool QualType::isCXX11PODType(const ASTContext &Context) const {
  const Type *ty = getTypePtr();
  if (ty->isDependentType())
    return false;

  if (hasNonTrivialObjCLifetime())
    return false;

  // C++11 [basic.types]p9:
  //   Scalar types, POD classes, arrays of such types, and cv-qualified
  //   versions of these types are collectively called trivial types.
  const Type *BaseTy = ty->getBaseElementTypeUnsafe();
  assert(BaseTy && "NULL element type");

  if (BaseTy->isSizelessBuiltinType())
    return true;

  // Return false for incomplete types after skipping any incomplete array
  // types which are expressly allowed by the standard and thus our API.
  if (BaseTy->isIncompleteType())
    return false;

  // As an extension, Clang treats vector types as Scalar types.
  if (BaseTy->isScalarType() || BaseTy->isVectorType()) return true;
  if (const auto *RT = BaseTy->getAs<RecordType>()) {
    if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
      // C++11 [class]p10:
      //   A POD struct is a non-union class that is both a trivial class [...]
      if (!ClassDecl->isTrivial()) return false;

      // C++11 [class]p10:
      //   A POD struct is a non-union class that is both a trivial class and
      //   a standard-layout class [...]
      if (!ClassDecl->isStandardLayout()) return false;

      // C++11 [class]p10:
      //   A POD struct is a non-union class that is both a trivial class and
      //   a standard-layout class, and has no non-static data members of type
      //   non-POD struct, non-POD union (or array of such types). [...]
      //
      // We don't directly query the recursive aspect as the requirements for
      // both standard-layout classes and trivial classes apply recursively
      // already.
    }

    return true;
  }

  // No other types can match.
  return false;
}

bool Type::isNothrowT() const {
  if (const auto *RD = getAsCXXRecordDecl()) {
    IdentifierInfo *II = RD->getIdentifier();
    if (II && II->isStr("nothrow_t") && RD->isInStdNamespace())
      return true;
  }
  return false;
}

bool Type::isAlignValT() const {
  if (const auto *ET = getAs<EnumType>()) {
    IdentifierInfo *II = ET->getDecl()->getIdentifier();
    if (II && II->isStr("align_val_t") && ET->getDecl()->isInStdNamespace())
      return true;
  }
  return false;
}

bool Type::isStdByteType() const {
  if (const auto *ET = getAs<EnumType>()) {
    IdentifierInfo *II = ET->getDecl()->getIdentifier();
    if (II && II->isStr("byte") && ET->getDecl()->isInStdNamespace())
      return true;
  }
  return false;
}

bool Type::isPromotableIntegerType() const {
  if (const auto *BT = getAs<BuiltinType>())
    switch (BT->getKind()) {
    case BuiltinType::Bool:
    case BuiltinType::Char_S:
    case BuiltinType::Char_U:
    case BuiltinType::SChar:
    case BuiltinType::UChar:
    case BuiltinType::Short:
    case BuiltinType::UShort:
    case BuiltinType::WChar_S:
    case BuiltinType::WChar_U:
    case BuiltinType::Char8:
    case BuiltinType::Char16:
    case BuiltinType::Char32:
      return true;
    default:
      return false;
    }

  // Enumerated types are promotable to their compatible integer types
  // (C99 6.3.1.1) a.k.a. its underlying type (C++ [conv.prom]p2).
  if (const auto *ET = getAs<EnumType>()){
    if (this->isDependentType() || ET->getDecl()->getPromotionType().isNull()
        || ET->getDecl()->isScoped())
      return false;

    return true;
  }

  return false;
}

bool Type::isSpecifierType() const {
  // Note that this intentionally does not use the canonical type.
  switch (getTypeClass()) {
  case Builtin:
  case Record:
  case Enum:
  case Typedef:
  case Complex:
  case TypeOfExpr:
  case TypeOf:
  case TemplateTypeParm:
  case SubstTemplateTypeParm:
  case TemplateSpecialization:
  case Elaborated:
  case DependentName:
  case DependentTemplateSpecialization:
  case ObjCInterface:
  case ObjCObject:
  case ObjCObjectPointer: // FIXME: object pointers aren't really specifiers
    return true;
  default:
    return false;
  }
}

ElaboratedTypeKeyword
TypeWithKeyword::getKeywordForTypeSpec(unsigned TypeSpec) {
  switch (TypeSpec) {
  default: return ETK_None;
  case TST_typename: return ETK_Typename;
  case TST_class: return ETK_Class;
  case TST_struct: return ETK_Struct;
  case TST_interface: return ETK_Interface;
  case TST_union: return ETK_Union;
  case TST_enum: return ETK_Enum;
  }
}

TagTypeKind
TypeWithKeyword::getTagTypeKindForTypeSpec(unsigned TypeSpec) {
  switch(TypeSpec) {
  case TST_class: return TTK_Class;
  case TST_struct: return TTK_Struct;
  case TST_interface: return TTK_Interface;
  case TST_union: return TTK_Union;
  case TST_enum: return TTK_Enum;
  }

  llvm_unreachable("Type specifier is not a tag type kind.");
}

ElaboratedTypeKeyword
TypeWithKeyword::getKeywordForTagTypeKind(TagTypeKind Kind) {
  switch (Kind) {
  case TTK_Class: return ETK_Class;
  case TTK_Struct: return ETK_Struct;
  case TTK_Interface: return ETK_Interface;
  case TTK_Union: return ETK_Union;
  case TTK_Enum: return ETK_Enum;
  }
  llvm_unreachable("Unknown tag type kind.");
}

TagTypeKind
TypeWithKeyword::getTagTypeKindForKeyword(ElaboratedTypeKeyword Keyword) {
  switch (Keyword) {
  case ETK_Class: return TTK_Class;
  case ETK_Struct: return TTK_Struct;
  case ETK_Interface: return TTK_Interface;
  case ETK_Union: return TTK_Union;
  case ETK_Enum: return TTK_Enum;
  case ETK_None: // Fall through.
  case ETK_Typename:
    llvm_unreachable("Elaborated type keyword is not a tag type kind.");
  }
  llvm_unreachable("Unknown elaborated type keyword.");
}

bool
TypeWithKeyword::KeywordIsTagTypeKind(ElaboratedTypeKeyword Keyword) {
  switch (Keyword) {
  case ETK_None:
  case ETK_Typename:
    return false;
  case ETK_Class:
  case ETK_Struct:
  case ETK_Interface:
  case ETK_Union:
  case ETK_Enum:
    return true;
  }
  llvm_unreachable("Unknown elaborated type keyword.");
}

StringRef TypeWithKeyword::getKeywordName(ElaboratedTypeKeyword Keyword) {
  switch (Keyword) {
  case ETK_None: return {};
  case ETK_Typename: return "typename";
  case ETK_Class:  return "class";
  case ETK_Struct: return "struct";
  case ETK_Interface: return "__interface";
  case ETK_Union:  return "union";
  case ETK_Enum:   return "enum";
  }

  llvm_unreachable("Unknown elaborated type keyword.");
}

DependentTemplateSpecializationType::DependentTemplateSpecializationType(
    ElaboratedTypeKeyword Keyword, NestedNameSpecifier *NNS,
    const IdentifierInfo *Name, ArrayRef<TemplateArgument> Args, QualType Canon)
    : TypeWithKeyword(Keyword, DependentTemplateSpecialization, Canon,
                      TypeDependence::DependentInstantiation |
                          (NNS ? toTypeDependence(NNS->getDependence())
                               : TypeDependence::None)),
      NNS(NNS), Name(Name) {
  DependentTemplateSpecializationTypeBits.NumArgs = Args.size();
  assert((!NNS || NNS->isDependent()) &&
         "DependentTemplateSpecializatonType requires dependent qualifier");
  TemplateArgument *ArgBuffer = getArgBuffer();
  for (const TemplateArgument &Arg : Args) {
    addDependence(toTypeDependence(Arg.getDependence() &
                                   TemplateArgumentDependence::UnexpandedPack));

    new (ArgBuffer++) TemplateArgument(Arg);
  }
}

void
DependentTemplateSpecializationType::Profile(llvm::FoldingSetNodeID &ID,
                                             const ASTContext &Context,
                                             ElaboratedTypeKeyword Keyword,
                                             NestedNameSpecifier *Qualifier,
                                             const IdentifierInfo *Name,
                                             ArrayRef<TemplateArgument> Args) {
  ID.AddInteger(Keyword);
  ID.AddPointer(Qualifier);
  ID.AddPointer(Name);
  for (const TemplateArgument &Arg : Args)
    Arg.Profile(ID, Context);
}

bool Type::isElaboratedTypeSpecifier() const {
  ElaboratedTypeKeyword Keyword;
  if (const auto *Elab = dyn_cast<ElaboratedType>(this))
    Keyword = Elab->getKeyword();
  else if (const auto *DepName = dyn_cast<DependentNameType>(this))
    Keyword = DepName->getKeyword();
  else if (const auto *DepTST =
               dyn_cast<DependentTemplateSpecializationType>(this))
    Keyword = DepTST->getKeyword();
  else
    return false;

  return TypeWithKeyword::KeywordIsTagTypeKind(Keyword);
}

const char *Type::getTypeClassName() const {
  switch (TypeBits.TC) {
#define ABSTRACT_TYPE(Derived, Base)
#define TYPE(Derived, Base) case Derived: return #Derived;
#include "clang/AST/TypeNodes.inc"
  }

  llvm_unreachable("Invalid type class.");
}

StringRef BuiltinType::getName(const PrintingPolicy &Policy) const {
  switch (getKind()) {
  case Void:
    return "void";
  case Bool:
    return Policy.Bool ? "bool" : "_Bool";
  case Char_S:
    return "char";
  case Char_U:
    return "char";
  case SChar:
    return "signed char";
  case Short:
    return "short";
  case Int:
    return "int";
  case Long:
    return "long";
  case LongLong:
    return "long long";
  case Int128:
    return "__int128";
  case UChar:
    return "unsigned char";
  case UShort:
    return "unsigned short";
  case UInt:
    return "unsigned int";
  case ULong:
    return "unsigned long";
  case ULongLong:
    return "unsigned long long";
  case UInt128:
    return "unsigned __int128";
  case Half:
    return Policy.Half ? "half" : "__fp16";
  case BFloat16:
    return "__bf16";
  case Float:
    return "float";
  case Double:
    return "double";
  case LongDouble:
    return "long double";
  case ShortAccum:
    return "short _Accum";
  case Accum:
    return "_Accum";
  case LongAccum:
    return "long _Accum";
  case UShortAccum:
    return "unsigned short _Accum";
  case UAccum:
    return "unsigned _Accum";
  case ULongAccum:
    return "unsigned long _Accum";
  case BuiltinType::ShortFract:
    return "short _Fract";
  case BuiltinType::Fract:
    return "_Fract";
  case BuiltinType::LongFract:
    return "long _Fract";
  case BuiltinType::UShortFract:
    return "unsigned short _Fract";
  case BuiltinType::UFract:
    return "unsigned _Fract";
  case BuiltinType::ULongFract:
    return "unsigned long _Fract";
  case BuiltinType::SatShortAccum:
    return "_Sat short _Accum";
  case BuiltinType::SatAccum:
    return "_Sat _Accum";
  case BuiltinType::SatLongAccum:
    return "_Sat long _Accum";
  case BuiltinType::SatUShortAccum:
    return "_Sat unsigned short _Accum";
  case BuiltinType::SatUAccum:
    return "_Sat unsigned _Accum";
  case BuiltinType::SatULongAccum:
    return "_Sat unsigned long _Accum";
  case BuiltinType::SatShortFract:
    return "_Sat short _Fract";
  case BuiltinType::SatFract:
    return "_Sat _Fract";
  case BuiltinType::SatLongFract:
    return "_Sat long _Fract";
  case BuiltinType::SatUShortFract:
    return "_Sat unsigned short _Fract";
  case BuiltinType::SatUFract:
    return "_Sat unsigned _Fract";
  case BuiltinType::SatULongFract:
    return "_Sat unsigned long _Fract";
  case Float16:
    return "_Float16";
  case Float128:
    return "__float128";
  case WChar_S:
  case WChar_U:
    return Policy.MSWChar ? "__wchar_t" : "wchar_t";
  case Char8:
    return "char8_t";
  case Char16:
    return "char16_t";
  case Char32:
    return "char32_t";
  case NullPtr:
    return "nullptr_t";
  case Overload:
    return "<overloaded function type>";
  case BoundMember:
    return "<bound member function type>";
  case PseudoObject:
    return "<pseudo-object type>";
  case Dependent:
    return "<dependent type>";
  case UnknownAny:
    return "<unknown type>";
  case ARCUnbridgedCast:
    return "<ARC unbridged cast type>";
  case BuiltinFn:
    return "<builtin fn type>";
  case ObjCId:
    return "id";
  case ObjCClass:
    return "Class";
  case ObjCSel:
    return "SEL";
#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
  case Id: \
    return "__" #Access " " #ImgType "_t";
#include "clang/Basic/OpenCLImageTypes.def"
  case OCLSampler:
    return "sampler_t";
  case OCLEvent:
    return "event_t";
  case OCLClkEvent:
    return "clk_event_t";
  case OCLQueue:
    return "queue_t";
  case OCLReserveID:
    return "reserve_id_t";
  case IncompleteMatrixIdx:
    return "<incomplete matrix index type>";
  case OMPArraySection:
    return "<OpenMP array section type>";
  case OMPArrayShaping:
    return "<OpenMP array shaping type>";
  case OMPIterator:
    return "<OpenMP iterator type>";
#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
  case Id: \
    return #ExtType;
#include "clang/Basic/OpenCLExtensionTypes.def"
#define SVE_TYPE(Name, Id, SingletonId) \
  case Id: \
    return Name;
#include "clang/Basic/AArch64SVEACLETypes.def"
  }

  llvm_unreachable("Invalid builtin type.");
}

QualType QualType::getNonPackExpansionType() const {
  // We never wrap type sugar around a PackExpansionType.
  if (auto *PET = dyn_cast<PackExpansionType>(getTypePtr()))
    return PET->getPattern();
  return *this;
}

QualType QualType::getNonLValueExprType(const ASTContext &Context) const {
  if (const auto *RefType = getTypePtr()->getAs<ReferenceType>())
    return RefType->getPointeeType();

  // C++0x [basic.lval]:
  //   Class prvalues can have cv-qualified types; non-class prvalues always
  //   have cv-unqualified types.
  //
  // See also C99 6.3.2.1p2.
  if (!Context.getLangOpts().CPlusPlus ||
      (!getTypePtr()->isDependentType() && !getTypePtr()->isRecordType()))
    return getUnqualifiedType();

  return *this;
}

StringRef FunctionType::getNameForCallConv(CallingConv CC) {
  switch (CC) {
  case CC_C: return "cdecl";
  case CC_X86StdCall: return "stdcall";
  case CC_X86FastCall: return "fastcall";
  case CC_X86ThisCall: return "thiscall";
  case CC_X86Pascal: return "pascal";
  case CC_X86VectorCall: return "vectorcall";
  case CC_Win64: return "ms_abi";
  case CC_X86_64SysV: return "sysv_abi";
  case CC_X86RegCall : return "regcall";
  case CC_AAPCS: return "aapcs";
  case CC_AAPCS_VFP: return "aapcs-vfp";
  case CC_AArch64VectorCall: return "aarch64_vector_pcs";
  case CC_IntelOclBicc: return "intel_ocl_bicc";
  case CC_SpirFunction: return "spir_function";
  case CC_OpenCLKernel: return "opencl_kernel";
  case CC_Swift: return "swiftcall";
  case CC_PreserveMost: return "preserve_most";
  case CC_PreserveAll: return "preserve_all";
  }

  llvm_unreachable("Invalid calling convention.");
}

FunctionProtoType::FunctionProtoType(QualType result, ArrayRef<QualType> params,
                                     QualType canonical,
                                     const ExtProtoInfo &epi)
    : FunctionType(FunctionProto, result, canonical, result->getDependence(),
                   epi.ExtInfo) {
  FunctionTypeBits.FastTypeQuals = epi.TypeQuals.getFastQualifiers();
  FunctionTypeBits.RefQualifier = epi.RefQualifier;
  FunctionTypeBits.NumParams = params.size();
  assert(getNumParams() == params.size() && "NumParams overflow!");
  FunctionTypeBits.ExceptionSpecType = epi.ExceptionSpec.Type;
  FunctionTypeBits.HasExtParameterInfos = !!epi.ExtParameterInfos;
  FunctionTypeBits.Variadic = epi.Variadic;
  FunctionTypeBits.HasTrailingReturn = epi.HasTrailingReturn;

  // Fill in the extra trailing bitfields if present.
  if (hasExtraBitfields(epi.ExceptionSpec.Type)) {
    auto &ExtraBits = *getTrailingObjects<FunctionTypeExtraBitfields>();
    ExtraBits.NumExceptionType = epi.ExceptionSpec.Exceptions.size();
  }

  // Fill in the trailing argument array.
  auto *argSlot = getTrailingObjects<QualType>();
  for (unsigned i = 0; i != getNumParams(); ++i) {
    addDependence(params[i]->getDependence() &
                  ~TypeDependence::VariablyModified);
    argSlot[i] = params[i];
  }

  // Fill in the exception type array if present.
  if (getExceptionSpecType() == EST_Dynamic) {
    assert(hasExtraBitfields() && "missing trailing extra bitfields!");
    auto *exnSlot =
        reinterpret_cast<QualType *>(getTrailingObjects<ExceptionType>());
    unsigned I = 0;
    for (QualType ExceptionType : epi.ExceptionSpec.Exceptions) {
      // Note that, before C++17, a dependent exception specification does
      // *not* make a type dependent; it's not even part of the C++ type
      // system.
      addDependence(
          ExceptionType->getDependence() &
          (TypeDependence::Instantiation | TypeDependence::UnexpandedPack));

      exnSlot[I++] = ExceptionType;
    }
  }
  // Fill in the Expr * in the exception specification if present.
  else if (isComputedNoexcept(getExceptionSpecType())) {
    assert(epi.ExceptionSpec.NoexceptExpr && "computed noexcept with no expr");
    assert((getExceptionSpecType() == EST_DependentNoexcept) ==
           epi.ExceptionSpec.NoexceptExpr->isValueDependent());

    // Store the noexcept expression and context.
    *getTrailingObjects<Expr *>() = epi.ExceptionSpec.NoexceptExpr;

    addDependence(
        toTypeDependence(epi.ExceptionSpec.NoexceptExpr->getDependence()) &
        (TypeDependence::Instantiation | TypeDependence::UnexpandedPack));
  }
  // Fill in the FunctionDecl * in the exception specification if present.
  else if (getExceptionSpecType() == EST_Uninstantiated) {
    // Store the function decl from which we will resolve our
    // exception specification.
    auto **slot = getTrailingObjects<FunctionDecl *>();
    slot[0] = epi.ExceptionSpec.SourceDecl;
    slot[1] = epi.ExceptionSpec.SourceTemplate;
    // This exception specification doesn't make the type dependent, because
    // it's not instantiated as part of instantiating the type.
  } else if (getExceptionSpecType() == EST_Unevaluated) {
    // Store the function decl from which we will resolve our
    // exception specification.
    auto **slot = getTrailingObjects<FunctionDecl *>();
    slot[0] = epi.ExceptionSpec.SourceDecl;
  }

  // If this is a canonical type, and its exception specification is dependent,
  // then it's a dependent type. This only happens in C++17 onwards.
  if (isCanonicalUnqualified()) {
    if (getExceptionSpecType() == EST_Dynamic ||
        getExceptionSpecType() == EST_DependentNoexcept) {
      assert(hasDependentExceptionSpec() && "type should not be canonical");
      addDependence(TypeDependence::DependentInstantiation);
    }
  } else if (getCanonicalTypeInternal()->isDependentType()) {
    // Ask our canonical type whether our exception specification was dependent.
    addDependence(TypeDependence::DependentInstantiation);
  }

  // Fill in the extra parameter info if present.
  if (epi.ExtParameterInfos) {
    auto *extParamInfos = getTrailingObjects<ExtParameterInfo>();
    for (unsigned i = 0; i != getNumParams(); ++i)
      extParamInfos[i] = epi.ExtParameterInfos[i];
  }

  if (epi.TypeQuals.hasNonFastQualifiers()) {
    FunctionTypeBits.HasExtQuals = 1;
    *getTrailingObjects<Qualifiers>() = epi.TypeQuals;
  } else {
    FunctionTypeBits.HasExtQuals = 0;
  }

  // Fill in the Ellipsis location info if present.
  if (epi.Variadic) {
    auto &EllipsisLoc = *getTrailingObjects<SourceLocation>();
    EllipsisLoc = epi.EllipsisLoc;
  }
}

bool FunctionProtoType::hasDependentExceptionSpec() const {
  if (Expr *NE = getNoexceptExpr())
    return NE->isValueDependent();
  for (QualType ET : exceptions())
    // A pack expansion with a non-dependent pattern is still dependent,
    // because we don't know whether the pattern is in the exception spec
    // or not (that depends on whether the pack has 0 expansions).
    if (ET->isDependentType() || ET->getAs<PackExpansionType>())
      return true;
  return false;
}

bool FunctionProtoType::hasInstantiationDependentExceptionSpec() const {
  if (Expr *NE = getNoexceptExpr())
    return NE->isInstantiationDependent();
  for (QualType ET : exceptions())
    if (ET->isInstantiationDependentType())
      return true;
  return false;
}

CanThrowResult FunctionProtoType::canThrow() const {
  switch (getExceptionSpecType()) {
  case EST_Unparsed:
  case EST_Unevaluated:
  case EST_Uninstantiated:
    llvm_unreachable("should not call this with unresolved exception specs");

  case EST_DynamicNone:
  case EST_BasicNoexcept:
  case EST_NoexceptTrue:
  case EST_NoThrow:
    return CT_Cannot;

  case EST_None:
  case EST_MSAny:
  case EST_NoexceptFalse:
    return CT_Can;

  case EST_Dynamic:
    // A dynamic exception specification is throwing unless every exception
    // type is an (unexpanded) pack expansion type.
    for (unsigned I = 0; I != getNumExceptions(); ++I)
      if (!getExceptionType(I)->getAs<PackExpansionType>())
        return CT_Can;
    return CT_Dependent;

  case EST_DependentNoexcept:
    return CT_Dependent;
  }

  llvm_unreachable("unexpected exception specification kind");
}

bool FunctionProtoType::isTemplateVariadic() const {
  for (unsigned ArgIdx = getNumParams(); ArgIdx; --ArgIdx)
    if (isa<PackExpansionType>(getParamType(ArgIdx - 1)))
      return true;

  return false;
}

void FunctionProtoType::Profile(llvm::FoldingSetNodeID &ID, QualType Result,
                                const QualType *ArgTys, unsigned NumParams,
                                const ExtProtoInfo &epi,
                                const ASTContext &Context, bool Canonical) {
  // We have to be careful not to get ambiguous profile encodings.
  // Note that valid type pointers are never ambiguous with anything else.
  //
  // The encoding grammar begins:
  //      type type* bool int bool
  // If that final bool is true, then there is a section for the EH spec:
  //      bool type*
  // This is followed by an optional "consumed argument" section of the
  // same length as the first type sequence:
  //      bool*
  // Finally, we have the ext info and trailing return type flag:
  //      int bool
  //
  // There is no ambiguity between the consumed arguments and an empty EH
  // spec because of the leading 'bool' which unambiguously indicates
  // whether the following bool is the EH spec or part of the arguments.

  ID.AddPointer(Result.getAsOpaquePtr());
  for (unsigned i = 0; i != NumParams; ++i)
    ID.AddPointer(ArgTys[i].getAsOpaquePtr());
  // This method is relatively performance sensitive, so as a performance
  // shortcut, use one AddInteger call instead of four for the next four
  // fields.
  assert(!(unsigned(epi.Variadic) & ~1) &&
         !(unsigned(epi.RefQualifier) & ~3) &&
         !(unsigned(epi.ExceptionSpec.Type) & ~15) &&
         "Values larger than expected.");
  ID.AddInteger(unsigned(epi.Variadic) +
                (epi.RefQualifier << 1) +
                (epi.ExceptionSpec.Type << 3));
  ID.Add(epi.TypeQuals);
  if (epi.ExceptionSpec.Type == EST_Dynamic) {
    for (QualType Ex : epi.ExceptionSpec.Exceptions)
      ID.AddPointer(Ex.getAsOpaquePtr());
  } else if (isComputedNoexcept(epi.ExceptionSpec.Type)) {
    epi.ExceptionSpec.NoexceptExpr->Profile(ID, Context, Canonical);
  } else if (epi.ExceptionSpec.Type == EST_Uninstantiated ||
             epi.ExceptionSpec.Type == EST_Unevaluated) {
    ID.AddPointer(epi.ExceptionSpec.SourceDecl->getCanonicalDecl());
  }
  if (epi.ExtParameterInfos) {
    for (unsigned i = 0; i != NumParams; ++i)
      ID.AddInteger(epi.ExtParameterInfos[i].getOpaqueValue());
  }
  epi.ExtInfo.Profile(ID);
  ID.AddBoolean(epi.HasTrailingReturn);
}

void FunctionProtoType::Profile(llvm::FoldingSetNodeID &ID,
                                const ASTContext &Ctx) {
  Profile(ID, getReturnType(), param_type_begin(), getNumParams(),
          getExtProtoInfo(), Ctx, isCanonicalUnqualified());
}

TypedefType::TypedefType(TypeClass tc, const TypedefNameDecl *D, QualType can)
    : Type(tc, can, D->getUnderlyingType()->getDependence()),
      Decl(const_cast<TypedefNameDecl *>(D)) {
  assert(!isa<TypedefType>(can) && "Invalid canonical type");
}

QualType TypedefType::desugar() const {
  return getDecl()->getUnderlyingType();
}

QualType MacroQualifiedType::desugar() const { return getUnderlyingType(); }

QualType MacroQualifiedType::getModifiedType() const {
  // Step over MacroQualifiedTypes from the same macro to find the type
  // ultimately qualified by the macro qualifier.
  QualType Inner = cast<AttributedType>(getUnderlyingType())->getModifiedType();
  while (auto *InnerMQT = dyn_cast<MacroQualifiedType>(Inner)) {
    if (InnerMQT->getMacroIdentifier() != getMacroIdentifier())
      break;
    Inner = InnerMQT->getModifiedType();
  }
  return Inner;
}

TypeOfExprType::TypeOfExprType(Expr *E, QualType can)
    : Type(TypeOfExpr, can,
           toTypeDependence(E->getDependence()) |
               (E->getType()->getDependence() &
                TypeDependence::VariablyModified)),
      TOExpr(E) {}

bool TypeOfExprType::isSugared() const {
  return !TOExpr->isTypeDependent();
}

QualType TypeOfExprType::desugar() const {
  if (isSugared())
    return getUnderlyingExpr()->getType();

  return QualType(this, 0);
}

void DependentTypeOfExprType::Profile(llvm::FoldingSetNodeID &ID,
                                      const ASTContext &Context, Expr *E) {
  E->Profile(ID, Context, true);
}

DecltypeType::DecltypeType(Expr *E, QualType underlyingType, QualType can)
    // C++11 [temp.type]p2: "If an expression e involves a template parameter,
    // decltype(e) denotes a unique dependent type." Hence a decltype type is
    // type-dependent even if its expression is only instantiation-dependent.
    : Type(Decltype, can,
           toTypeDependence(E->getDependence()) |
               (E->isInstantiationDependent() ? TypeDependence::Dependent
                                              : TypeDependence::None) |
               (E->getType()->getDependence() &
                TypeDependence::VariablyModified)),
      E(E), UnderlyingType(underlyingType) {}

bool DecltypeType::isSugared() const { return !E->isInstantiationDependent(); }

QualType DecltypeType::desugar() const {
  if (isSugared())
    return getUnderlyingType();

  return QualType(this, 0);
}

DependentDecltypeType::DependentDecltypeType(const ASTContext &Context, Expr *E)
    : DecltypeType(E, Context.DependentTy), Context(Context) {}

void DependentDecltypeType::Profile(llvm::FoldingSetNodeID &ID,
                                    const ASTContext &Context, Expr *E) {
  E->Profile(ID, Context, true);
}

UnaryTransformType::UnaryTransformType(QualType BaseType,
                                       QualType UnderlyingType, UTTKind UKind,
                                       QualType CanonicalType)
    : Type(UnaryTransform, CanonicalType, BaseType->getDependence()),
      BaseType(BaseType), UnderlyingType(UnderlyingType), UKind(UKind) {}

DependentUnaryTransformType::DependentUnaryTransformType(const ASTContext &C,
                                                         QualType BaseType,
                                                         UTTKind UKind)
     : UnaryTransformType(BaseType, C.DependentTy, UKind, QualType()) {}

TagType::TagType(TypeClass TC, const TagDecl *D, QualType can)
    : Type(TC, can,
           D->isDependentType() ? TypeDependence::DependentInstantiation
                                : TypeDependence::None),
      decl(const_cast<TagDecl *>(D)) {}

static TagDecl *getInterestingTagDecl(TagDecl *decl) {
  for (auto I : decl->redecls()) {
    if (I->isCompleteDefinition() || I->isBeingDefined())
      return I;
  }
  // If there's no definition (not even in progress), return what we have.
  return decl;
}

TagDecl *TagType::getDecl() const {
  return getInterestingTagDecl(decl);
}

bool TagType::isBeingDefined() const {
  return getDecl()->isBeingDefined();
}

bool RecordType::hasConstFields() const {
  std::vector<const RecordType*> RecordTypeList;
  RecordTypeList.push_back(this);
  unsigned NextToCheckIndex = 0;

  while (RecordTypeList.size() > NextToCheckIndex) {
    for (FieldDecl *FD :
         RecordTypeList[NextToCheckIndex]->getDecl()->fields()) {
      QualType FieldTy = FD->getType();
      if (FieldTy.isConstQualified())
        return true;
      FieldTy = FieldTy.getCanonicalType();
      if (const auto *FieldRecTy = FieldTy->getAs<RecordType>()) {
        if (llvm::find(RecordTypeList, FieldRecTy) == RecordTypeList.end())
          RecordTypeList.push_back(FieldRecTy);
      }
    }
    ++NextToCheckIndex;
  }
  return false;
}

bool AttributedType::isQualifier() const {
  // FIXME: Generate this with TableGen.
  switch (getAttrKind()) {
  // These are type qualifiers in the traditional C sense: they annotate
  // something about a specific value/variable of a type.  (They aren't
  // always part of the canonical type, though.)
  case attr::ObjCGC:
  case attr::ObjCOwnership:
  case attr::ObjCInertUnsafeUnretained:
  case attr::TypeNonNull:
  case attr::TypeNullable:
  case attr::TypeNullUnspecified:
  case attr::LifetimeBound:
  case attr::AddressSpace:
    return true;

  // All other type attributes aren't qualifiers; they rewrite the modified
  // type to be a semantically different type.
  default:
    return false;
  }
}

bool AttributedType::isMSTypeSpec() const {
  // FIXME: Generate this with TableGen?
  switch (getAttrKind()) {
  default: return false;
  case attr::Ptr32:
  case attr::Ptr64:
  case attr::SPtr:
  case attr::UPtr:
    return true;
  }
  llvm_unreachable("invalid attr kind");
}

bool AttributedType::isCallingConv() const {
  // FIXME: Generate this with TableGen.
  switch (getAttrKind()) {
  default: return false;
  case attr::Pcs:
  case attr::CDecl:
  case attr::FastCall:
  case attr::StdCall:
  case attr::ThisCall:
  case attr::RegCall:
  case attr::SwiftCall:
  case attr::VectorCall:
  case attr::AArch64VectorPcs:
  case attr::Pascal:
  case attr::MSABI:
  case attr::SysVABI:
  case attr::IntelOclBicc:
  case attr::PreserveMost:
  case attr::PreserveAll:
    return true;
  }
  llvm_unreachable("invalid attr kind");
}

CXXRecordDecl *InjectedClassNameType::getDecl() const {
  return cast<CXXRecordDecl>(getInterestingTagDecl(Decl));
}

IdentifierInfo *TemplateTypeParmType::getIdentifier() const {
  return isCanonicalUnqualified() ? nullptr : getDecl()->getIdentifier();
}

SubstTemplateTypeParmPackType::SubstTemplateTypeParmPackType(
    const TemplateTypeParmType *Param, QualType Canon,
    const TemplateArgument &ArgPack)
    : Type(SubstTemplateTypeParmPack, Canon,
           TypeDependence::DependentInstantiation |
               TypeDependence::UnexpandedPack),
      Replaced(Param), Arguments(ArgPack.pack_begin()) {
  SubstTemplateTypeParmPackTypeBits.NumArgs = ArgPack.pack_size();
}

TemplateArgument SubstTemplateTypeParmPackType::getArgumentPack() const {
  return TemplateArgument(llvm::makeArrayRef(Arguments, getNumArgs()));
}

void SubstTemplateTypeParmPackType::Profile(llvm::FoldingSetNodeID &ID) {
  Profile(ID, getReplacedParameter(), getArgumentPack());
}

void SubstTemplateTypeParmPackType::Profile(llvm::FoldingSetNodeID &ID,
                                           const TemplateTypeParmType *Replaced,
                                            const TemplateArgument &ArgPack) {
  ID.AddPointer(Replaced);
  ID.AddInteger(ArgPack.pack_size());
  for (const auto &P : ArgPack.pack_elements())
    ID.AddPointer(P.getAsType().getAsOpaquePtr());
}

bool TemplateSpecializationType::
anyDependentTemplateArguments(const TemplateArgumentListInfo &Args,
                              bool &InstantiationDependent) {
  return anyDependentTemplateArguments(Args.arguments(),
                                       InstantiationDependent);
}

bool TemplateSpecializationType::
anyDependentTemplateArguments(ArrayRef<TemplateArgumentLoc> Args,
                              bool &InstantiationDependent) {
  for (const TemplateArgumentLoc &ArgLoc : Args) {
    if (ArgLoc.getArgument().isDependent()) {
      InstantiationDependent = true;
      return true;
    }

    if (ArgLoc.getArgument().isInstantiationDependent())
      InstantiationDependent = true;
  }
  return false;
}

TemplateSpecializationType::TemplateSpecializationType(
    TemplateName T, ArrayRef<TemplateArgument> Args, QualType Canon,
    QualType AliasedType)
    : Type(TemplateSpecialization, Canon.isNull() ? QualType(this, 0) : Canon,
           (Canon.isNull()
                ? TypeDependence::DependentInstantiation
                : Canon->getDependence() & ~(TypeDependence::VariablyModified |
                                             TypeDependence::UnexpandedPack)) |
               (toTypeDependence(T.getDependence()) &
                TypeDependence::UnexpandedPack)),
      Template(T) {
  TemplateSpecializationTypeBits.NumArgs = Args.size();
  TemplateSpecializationTypeBits.TypeAlias = !AliasedType.isNull();

  assert(!T.getAsDependentTemplateName() &&
         "Use DependentTemplateSpecializationType for dependent template-name");
  assert((T.getKind() == TemplateName::Template ||
          T.getKind() == TemplateName::SubstTemplateTemplateParm ||
          T.getKind() == TemplateName::SubstTemplateTemplateParmPack) &&
         "Unexpected template name for TemplateSpecializationType");

  auto *TemplateArgs = reinterpret_cast<TemplateArgument *>(this + 1);
  for (const TemplateArgument &Arg : Args) {
    // Update instantiation-dependent, variably-modified, and error bits.
    // If the canonical type exists and is non-dependent, the template
    // specialization type can be non-dependent even if one of the type
    // arguments is. Given:
    //   template<typename T> using U = int;
    // U<T> is always non-dependent, irrespective of the type T.
    // However, U<Ts> contains an unexpanded parameter pack, even though
    // its expansion (and thus its desugared type) doesn't.
    addDependence(toTypeDependence(Arg.getDependence()) &
                  ~TypeDependence::Dependent);
    if (Arg.getKind() == TemplateArgument::Type)
      addDependence(Arg.getAsType()->getDependence() &
                    TypeDependence::VariablyModified);
    new (TemplateArgs++) TemplateArgument(Arg);
  }

  // Store the aliased type if this is a type alias template specialization.
  if (isTypeAlias()) {
    auto *Begin = reinterpret_cast<TemplateArgument *>(this + 1);
    *reinterpret_cast<QualType*>(Begin + getNumArgs()) = AliasedType;
  }
}

void
TemplateSpecializationType::Profile(llvm::FoldingSetNodeID &ID,
                                    TemplateName T,
                                    ArrayRef<TemplateArgument> Args,
                                    const ASTContext &Context) {
  T.Profile(ID);
  for (const TemplateArgument &Arg : Args)
    Arg.Profile(ID, Context);
}

QualType
QualifierCollector::apply(const ASTContext &Context, QualType QT) const {
  if (!hasNonFastQualifiers())
    return QT.withFastQualifiers(getFastQualifiers());

  return Context.getQualifiedType(QT, *this);
}

QualType
QualifierCollector::apply(const ASTContext &Context, const Type *T) const {
  if (!hasNonFastQualifiers())
    return QualType(T, getFastQualifiers());

  return Context.getQualifiedType(T, *this);
}

void ObjCObjectTypeImpl::Profile(llvm::FoldingSetNodeID &ID,
                                 QualType BaseType,
                                 ArrayRef<QualType> typeArgs,
                                 ArrayRef<ObjCProtocolDecl *> protocols,
                                 bool isKindOf) {
  ID.AddPointer(BaseType.getAsOpaquePtr());
  ID.AddInteger(typeArgs.size());
  for (auto typeArg : typeArgs)
    ID.AddPointer(typeArg.getAsOpaquePtr());
  ID.AddInteger(protocols.size());
  for (auto proto : protocols)
    ID.AddPointer(proto);
  ID.AddBoolean(isKindOf);
}

void ObjCObjectTypeImpl::Profile(llvm::FoldingSetNodeID &ID) {
  Profile(ID, getBaseType(), getTypeArgsAsWritten(),
          llvm::makeArrayRef(qual_begin(), getNumProtocols()),
          isKindOfTypeAsWritten());
}

void ObjCTypeParamType::Profile(llvm::FoldingSetNodeID &ID,
                                const ObjCTypeParamDecl *OTPDecl,
                                QualType CanonicalType,
                                ArrayRef<ObjCProtocolDecl *> protocols) {
  ID.AddPointer(OTPDecl);
  ID.AddPointer(CanonicalType.getAsOpaquePtr());
  ID.AddInteger(protocols.size());
  for (auto proto : protocols)
    ID.AddPointer(proto);
}

void ObjCTypeParamType::Profile(llvm::FoldingSetNodeID &ID) {
  Profile(ID, getDecl(), getCanonicalTypeInternal(),
          llvm::makeArrayRef(qual_begin(), getNumProtocols()));
}

namespace {

/// The cached properties of a type.
class CachedProperties {
  Linkage L;
  bool local;

public:
  CachedProperties(Linkage L, bool local) : L(L), local(local) {}

  Linkage getLinkage() const { return L; }
  bool hasLocalOrUnnamedType() const { return local; }

  friend CachedProperties merge(CachedProperties L, CachedProperties R) {
    Linkage MergedLinkage = minLinkage(L.L, R.L);
    return CachedProperties(MergedLinkage,
                         L.hasLocalOrUnnamedType() | R.hasLocalOrUnnamedType());
  }
};

} // namespace

static CachedProperties computeCachedProperties(const Type *T);

namespace clang {

/// The type-property cache.  This is templated so as to be
/// instantiated at an internal type to prevent unnecessary symbol
/// leakage.
template <class Private> class TypePropertyCache {
public:
  static CachedProperties get(QualType T) {
    return get(T.getTypePtr());
  }

  static CachedProperties get(const Type *T) {
    ensure(T);
    return CachedProperties(T->TypeBits.getLinkage(),
                            T->TypeBits.hasLocalOrUnnamedType());
  }

  static void ensure(const Type *T) {
    // If the cache is valid, we're okay.
    if (T->TypeBits.isCacheValid()) return;

    // If this type is non-canonical, ask its canonical type for the
    // relevant information.
    if (!T->isCanonicalUnqualified()) {
      const Type *CT = T->getCanonicalTypeInternal().getTypePtr();
      ensure(CT);
      T->TypeBits.CacheValid = true;
      T->TypeBits.CachedLinkage = CT->TypeBits.CachedLinkage;
      T->TypeBits.CachedLocalOrUnnamed = CT->TypeBits.CachedLocalOrUnnamed;
      return;
    }

    // Compute the cached properties and then set the cache.
    CachedProperties Result = computeCachedProperties(T);
    T->TypeBits.CacheValid = true;
    T->TypeBits.CachedLinkage = Result.getLinkage();
    T->TypeBits.CachedLocalOrUnnamed = Result.hasLocalOrUnnamedType();
  }
};

} // namespace clang

// Instantiate the friend template at a private class.  In a
// reasonable implementation, these symbols will be internal.
// It is terrible that this is the best way to accomplish this.
namespace {

class Private {};

} // namespace

using Cache = TypePropertyCache<Private>;

static CachedProperties computeCachedProperties(const Type *T) {
  switch (T->getTypeClass()) {
#define TYPE(Class,Base)
#define NON_CANONICAL_TYPE(Class,Base) case Type::Class:
#include "clang/AST/TypeNodes.inc"
    llvm_unreachable("didn't expect a non-canonical type here");

#define TYPE(Class,Base)
#define DEPENDENT_TYPE(Class,Base) case Type::Class:
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class,Base) case Type::Class:
#include "clang/AST/TypeNodes.inc"
    // Treat instantiation-dependent types as external.
    if (!T->isInstantiationDependentType()) T->dump();
    assert(T->isInstantiationDependentType());
    return CachedProperties(ExternalLinkage, false);

  case Type::Auto:
  case Type::DeducedTemplateSpecialization:
    // Give non-deduced 'auto' types external linkage. We should only see them
    // here in error recovery.
    return CachedProperties(ExternalLinkage, false);

  case Type::ExtInt:
  case Type::Builtin:
    // C++ [basic.link]p8:
    //   A type is said to have linkage if and only if:
    //     - it is a fundamental type (3.9.1); or
    return CachedProperties(ExternalLinkage, false);

  case Type::Record:
  case Type::Enum: {
    const TagDecl *Tag = cast<TagType>(T)->getDecl();

    // C++ [basic.link]p8:
    //     - it is a class or enumeration type that is named (or has a name
    //       for linkage purposes (7.1.3)) and the name has linkage; or
    //     -  it is a specialization of a class template (14); or
    Linkage L = Tag->getLinkageInternal();
    bool IsLocalOrUnnamed =
      Tag->getDeclContext()->isFunctionOrMethod() ||
      !Tag->hasNameForLinkage();
    return CachedProperties(L, IsLocalOrUnnamed);
  }

    // C++ [basic.link]p8:
    //   - it is a compound type (3.9.2) other than a class or enumeration,
    //     compounded exclusively from types that have linkage; or
  case Type::Complex:
    return Cache::get(cast<ComplexType>(T)->getElementType());
  case Type::Pointer:
    return Cache::get(cast<PointerType>(T)->getPointeeType());
  case Type::BlockPointer:
    return Cache::get(cast<BlockPointerType>(T)->getPointeeType());
  case Type::LValueReference:
  case Type::RValueReference:
    return Cache::get(cast<ReferenceType>(T)->getPointeeType());
  case Type::MemberPointer: {
    const auto *MPT = cast<MemberPointerType>(T);
    return merge(Cache::get(MPT->getClass()),
                 Cache::get(MPT->getPointeeType()));
  }
  case Type::ConstantArray:
  case Type::IncompleteArray:
  case Type::VariableArray:
    return Cache::get(cast<ArrayType>(T)->getElementType());
  case Type::Vector:
  case Type::ExtVector:
    return Cache::get(cast<VectorType>(T)->getElementType());
  case Type::ConstantMatrix:
    return Cache::get(cast<ConstantMatrixType>(T)->getElementType());
  case Type::FunctionNoProto:
    return Cache::get(cast<FunctionType>(T)->getReturnType());
  case Type::FunctionProto: {
    const auto *FPT = cast<FunctionProtoType>(T);
    CachedProperties result = Cache::get(FPT->getReturnType());
    for (const auto &ai : FPT->param_types())
      result = merge(result, Cache::get(ai));
    return result;
  }
  case Type::ObjCInterface: {
    Linkage L = cast<ObjCInterfaceType>(T)->getDecl()->getLinkageInternal();
    return CachedProperties(L, false);
  }
  case Type::ObjCObject:
    return Cache::get(cast<ObjCObjectType>(T)->getBaseType());
  case Type::ObjCObjectPointer:
    return Cache::get(cast<ObjCObjectPointerType>(T)->getPointeeType());
  case Type::Atomic:
    return Cache::get(cast<AtomicType>(T)->getValueType());
  case Type::Pipe:
    return Cache::get(cast<PipeType>(T)->getElementType());
  }

  llvm_unreachable("unhandled type class");
}

/// Determine the linkage of this type.
Linkage Type::getLinkage() const {
  Cache::ensure(this);
  return TypeBits.getLinkage();
}

bool Type::hasUnnamedOrLocalType() const {
  Cache::ensure(this);
  return TypeBits.hasLocalOrUnnamedType();
}

LinkageInfo LinkageComputer::computeTypeLinkageInfo(const Type *T) {
  switch (T->getTypeClass()) {
#define TYPE(Class,Base)
#define NON_CANONICAL_TYPE(Class,Base) case Type::Class:
#include "clang/AST/TypeNodes.inc"
    llvm_unreachable("didn't expect a non-canonical type here");

#define TYPE(Class,Base)
#define DEPENDENT_TYPE(Class,Base) case Type::Class:
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class,Base) case Type::Class:
#include "clang/AST/TypeNodes.inc"
    // Treat instantiation-dependent types as external.
    assert(T->isInstantiationDependentType());
    return LinkageInfo::external();

  case Type::ExtInt:
  case Type::Builtin:
    return LinkageInfo::external();

  case Type::Auto:
  case Type::DeducedTemplateSpecialization:
    return LinkageInfo::external();

  case Type::Record:
  case Type::Enum:
    return getDeclLinkageAndVisibility(cast<TagType>(T)->getDecl());

  case Type::Complex:
    return computeTypeLinkageInfo(cast<ComplexType>(T)->getElementType());
  case Type::Pointer:
    return computeTypeLinkageInfo(cast<PointerType>(T)->getPointeeType());
  case Type::BlockPointer:
    return computeTypeLinkageInfo(cast<BlockPointerType>(T)->getPointeeType());
  case Type::LValueReference:
  case Type::RValueReference:
    return computeTypeLinkageInfo(cast<ReferenceType>(T)->getPointeeType());
  case Type::MemberPointer: {
    const auto *MPT = cast<MemberPointerType>(T);
    LinkageInfo LV = computeTypeLinkageInfo(MPT->getClass());
    LV.merge(computeTypeLinkageInfo(MPT->getPointeeType()));
    return LV;
  }
  case Type::ConstantArray:
  case Type::IncompleteArray:
  case Type::VariableArray:
    return computeTypeLinkageInfo(cast<ArrayType>(T)->getElementType());
  case Type::Vector:
  case Type::ExtVector:
    return computeTypeLinkageInfo(cast<VectorType>(T)->getElementType());
  case Type::ConstantMatrix:
    return computeTypeLinkageInfo(
        cast<ConstantMatrixType>(T)->getElementType());
  case Type::FunctionNoProto:
    return computeTypeLinkageInfo(cast<FunctionType>(T)->getReturnType());
  case Type::FunctionProto: {
    const auto *FPT = cast<FunctionProtoType>(T);
    LinkageInfo LV = computeTypeLinkageInfo(FPT->getReturnType());
    for (const auto &ai : FPT->param_types())
      LV.merge(computeTypeLinkageInfo(ai));
    return LV;
  }
  case Type::ObjCInterface:
    return getDeclLinkageAndVisibility(cast<ObjCInterfaceType>(T)->getDecl());
  case Type::ObjCObject:
    return computeTypeLinkageInfo(cast<ObjCObjectType>(T)->getBaseType());
  case Type::ObjCObjectPointer:
    return computeTypeLinkageInfo(
        cast<ObjCObjectPointerType>(T)->getPointeeType());
  case Type::Atomic:
    return computeTypeLinkageInfo(cast<AtomicType>(T)->getValueType());
  case Type::Pipe:
    return computeTypeLinkageInfo(cast<PipeType>(T)->getElementType());
  }

  llvm_unreachable("unhandled type class");
}

bool Type::isLinkageValid() const {
  if (!TypeBits.isCacheValid())
    return true;

  Linkage L = LinkageComputer{}
                  .computeTypeLinkageInfo(getCanonicalTypeInternal())
                  .getLinkage();
  return L == TypeBits.getLinkage();
}

LinkageInfo LinkageComputer::getTypeLinkageAndVisibility(const Type *T) {
  if (!T->isCanonicalUnqualified())
    return computeTypeLinkageInfo(T->getCanonicalTypeInternal());

  LinkageInfo LV = computeTypeLinkageInfo(T);
  assert(LV.getLinkage() == T->getLinkage());
  return LV;
}

LinkageInfo Type::getLinkageAndVisibility() const {
  return LinkageComputer{}.getTypeLinkageAndVisibility(this);
}

Optional<NullabilityKind>
Type::getNullability(const ASTContext &Context) const {
  QualType Type(this, 0);
  while (const auto *AT = Type->getAs<AttributedType>()) {
    // Check whether this is an attributed type with nullability
    // information.
    if (auto Nullability = AT->getImmediateNullability())
      return Nullability;

    Type = AT->getEquivalentType();
  }
  return None;
}

bool Type::canHaveNullability(bool ResultIfUnknown) const {
  QualType type = getCanonicalTypeInternal();

  switch (type->getTypeClass()) {
  // We'll only see canonical types here.
#define NON_CANONICAL_TYPE(Class, Parent)       \
  case Type::Class:                             \
    llvm_unreachable("non-canonical type");
#define TYPE(Class, Parent)
#include "clang/AST/TypeNodes.inc"

  // Pointer types.
  case Type::Pointer:
  case Type::BlockPointer:
  case Type::MemberPointer:
  case Type::ObjCObjectPointer:
    return true;

  // Dependent types that could instantiate to pointer types.
  case Type::UnresolvedUsing:
  case Type::TypeOfExpr:
  case Type::TypeOf:
  case Type::Decltype:
  case Type::UnaryTransform:
  case Type::TemplateTypeParm:
  case Type::SubstTemplateTypeParmPack:
  case Type::DependentName:
  case Type::DependentTemplateSpecialization:
  case Type::Auto:
    return ResultIfUnknown;

  // Dependent template specializations can instantiate to pointer
  // types unless they're known to be specializations of a class
  // template.
  case Type::TemplateSpecialization:
    if (TemplateDecl *templateDecl
          = cast<TemplateSpecializationType>(type.getTypePtr())
              ->getTemplateName().getAsTemplateDecl()) {
      if (isa<ClassTemplateDecl>(templateDecl))
        return false;
    }
    return ResultIfUnknown;

  case Type::Builtin:
    switch (cast<BuiltinType>(type.getTypePtr())->getKind()) {
      // Signed, unsigned, and floating-point types cannot have nullability.
#define SIGNED_TYPE(Id, SingletonId) case BuiltinType::Id:
#define UNSIGNED_TYPE(Id, SingletonId) case BuiltinType::Id:
#define FLOATING_TYPE(Id, SingletonId) case BuiltinType::Id:
#define BUILTIN_TYPE(Id, SingletonId)
#include "clang/AST/BuiltinTypes.def"
      return false;

    // Dependent types that could instantiate to a pointer type.
    case BuiltinType::Dependent:
    case BuiltinType::Overload:
    case BuiltinType::BoundMember:
    case BuiltinType::PseudoObject:
    case BuiltinType::UnknownAny:
    case BuiltinType::ARCUnbridgedCast:
      return ResultIfUnknown;

    case BuiltinType::Void:
    case BuiltinType::ObjCId:
    case BuiltinType::ObjCClass:
    case BuiltinType::ObjCSel:
#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
    case BuiltinType::Id:
#include "clang/Basic/OpenCLImageTypes.def"
#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
    case BuiltinType::Id:
#include "clang/Basic/OpenCLExtensionTypes.def"
    case BuiltinType::OCLSampler:
    case BuiltinType::OCLEvent:
    case BuiltinType::OCLClkEvent:
    case BuiltinType::OCLQueue:
    case BuiltinType::OCLReserveID:
#define SVE_TYPE(Name, Id, SingletonId) \
    case BuiltinType::Id:
#include "clang/Basic/AArch64SVEACLETypes.def"
    case BuiltinType::BuiltinFn:
    case BuiltinType::NullPtr:
    case BuiltinType::IncompleteMatrixIdx:
    case BuiltinType::OMPArraySection:
    case BuiltinType::OMPArrayShaping:
    case BuiltinType::OMPIterator:
      return false;
    }
    llvm_unreachable("unknown builtin type");

  // Non-pointer types.
  case Type::Complex:
  case Type::LValueReference:
  case Type::RValueReference:
  case Type::ConstantArray:
  case Type::IncompleteArray:
  case Type::VariableArray:
  case Type::DependentSizedArray:
  case Type::DependentVector:
  case Type::DependentSizedExtVector:
  case Type::Vector:
  case Type::ExtVector:
  case Type::ConstantMatrix:
  case Type::DependentSizedMatrix:
  case Type::DependentAddressSpace:
  case Type::FunctionProto:
  case Type::FunctionNoProto:
  case Type::Record:
  case Type::DeducedTemplateSpecialization:
  case Type::Enum:
  case Type::InjectedClassName:
  case Type::PackExpansion:
  case Type::ObjCObject:
  case Type::ObjCInterface:
  case Type::Atomic:
  case Type::Pipe:
  case Type::ExtInt:
  case Type::DependentExtInt:
    return false;
  }
  llvm_unreachable("bad type kind!");
}

llvm::Optional<NullabilityKind>
AttributedType::getImmediateNullability() const {
  if (getAttrKind() == attr::TypeNonNull)
    return NullabilityKind::NonNull;
  if (getAttrKind() == attr::TypeNullable)
    return NullabilityKind::Nullable;
  if (getAttrKind() == attr::TypeNullUnspecified)
    return NullabilityKind::Unspecified;
  return None;
}

Optional<NullabilityKind> AttributedType::stripOuterNullability(QualType &T) {
  QualType AttrTy = T;
  if (auto MacroTy = dyn_cast<MacroQualifiedType>(T))
    AttrTy = MacroTy->getUnderlyingType();

  if (auto attributed = dyn_cast<AttributedType>(AttrTy)) {
    if (auto nullability = attributed->getImmediateNullability()) {
      T = attributed->getModifiedType();
      return nullability;
    }
  }

  return None;
}

bool Type::isBlockCompatibleObjCPointerType(ASTContext &ctx) const {
  const auto *objcPtr = getAs<ObjCObjectPointerType>();
  if (!objcPtr)
    return false;

  if (objcPtr->isObjCIdType()) {
    // id is always okay.
    return true;
  }

  // Blocks are NSObjects.
  if (ObjCInterfaceDecl *iface = objcPtr->getInterfaceDecl()) {
    if (iface->getIdentifier() != ctx.getNSObjectName())
      return false;

    // Continue to check qualifiers, below.
  } else if (objcPtr->isObjCQualifiedIdType()) {
    // Continue to check qualifiers, below.
  } else {
    return false;
  }

  // Check protocol qualifiers.
  for (ObjCProtocolDecl *proto : objcPtr->quals()) {
    // Blocks conform to NSObject and NSCopying.
    if (proto->getIdentifier() != ctx.getNSObjectName() &&
        proto->getIdentifier() != ctx.getNSCopyingName())
      return false;
  }

  return true;
}

Qualifiers::ObjCLifetime Type::getObjCARCImplicitLifetime() const {
  if (isObjCARCImplicitlyUnretainedType())
    return Qualifiers::OCL_ExplicitNone;
  return Qualifiers::OCL_Strong;
}

bool Type::isObjCARCImplicitlyUnretainedType() const {
  assert(isObjCLifetimeType() &&
         "cannot query implicit lifetime for non-inferrable type");

  const Type *canon = getCanonicalTypeInternal().getTypePtr();

  // Walk down to the base type.  We don't care about qualifiers for this.
  while (const auto *array = dyn_cast<ArrayType>(canon))
    canon = array->getElementType().getTypePtr();

  if (const auto *opt = dyn_cast<ObjCObjectPointerType>(canon)) {
    // Class and Class<Protocol> don't require retention.
    if (opt->getObjectType()->isObjCClass())
      return true;
  }

  return false;
}

bool Type::isObjCNSObjectType() const {
  const Type *cur = this;
  while (true) {
    if (const auto *typedefType = dyn_cast<TypedefType>(cur))
      return typedefType->getDecl()->hasAttr<ObjCNSObjectAttr>();

    // Single-step desugar until we run out of sugar.
    QualType next = cur->getLocallyUnqualifiedSingleStepDesugaredType();
    if (next.getTypePtr() == cur) return false;
    cur = next.getTypePtr();
  }
}

bool Type::isObjCIndependentClassType() const {
  if (const auto *typedefType = dyn_cast<TypedefType>(this))
    return typedefType->getDecl()->hasAttr<ObjCIndependentClassAttr>();
  return false;
}

bool Type::isObjCRetainableType() const {
  return isObjCObjectPointerType() ||
         isBlockPointerType() ||
         isObjCNSObjectType();
}

bool Type::isObjCIndirectLifetimeType() const {
  if (isObjCLifetimeType())
    return true;
  if (const auto *OPT = getAs<PointerType>())
    return OPT->getPointeeType()->isObjCIndirectLifetimeType();
  if (const auto *Ref = getAs<ReferenceType>())
    return Ref->getPointeeType()->isObjCIndirectLifetimeType();
  if (const auto *MemPtr = getAs<MemberPointerType>())
    return MemPtr->getPointeeType()->isObjCIndirectLifetimeType();
  return false;
}

/// Returns true if objects of this type have lifetime semantics under
/// ARC.
bool Type::isObjCLifetimeType() const {
  const Type *type = this;
  while (const ArrayType *array = type->getAsArrayTypeUnsafe())
    type = array->getElementType().getTypePtr();
  return type->isObjCRetainableType();
}

/// Determine whether the given type T is a "bridgable" Objective-C type,
/// which is either an Objective-C object pointer type or an
bool Type::isObjCARCBridgableType() const {
  return isObjCObjectPointerType() || isBlockPointerType();
}

/// Determine whether the given type T is a "bridgeable" C type.
bool Type::isCARCBridgableType() const {
  const auto *Pointer = getAs<PointerType>();
  if (!Pointer)
    return false;

  QualType Pointee = Pointer->getPointeeType();
  return Pointee->isVoidType() || Pointee->isRecordType();
}

/// Check if the specified type is the CUDA device builtin surface type.
bool Type::isCUDADeviceBuiltinSurfaceType() const {
  if (const auto *RT = getAs<RecordType>())
    return RT->getDecl()->hasAttr<CUDADeviceBuiltinSurfaceTypeAttr>();
  return false;
}

/// Check if the specified type is the CUDA device builtin texture type.
bool Type::isCUDADeviceBuiltinTextureType() const {
  if (const auto *RT = getAs<RecordType>())
    return RT->getDecl()->hasAttr<CUDADeviceBuiltinTextureTypeAttr>();
  return false;
}

bool Type::hasSizedVLAType() const {
  if (!isVariablyModifiedType()) return false;

  if (const auto *ptr = getAs<PointerType>())
    return ptr->getPointeeType()->hasSizedVLAType();
  if (const auto *ref = getAs<ReferenceType>())
    return ref->getPointeeType()->hasSizedVLAType();
  if (const ArrayType *arr = getAsArrayTypeUnsafe()) {
    if (isa<VariableArrayType>(arr) &&
        cast<VariableArrayType>(arr)->getSizeExpr())
      return true;

    return arr->getElementType()->hasSizedVLAType();
  }

  return false;
}

QualType::DestructionKind QualType::isDestructedTypeImpl(QualType type) {
  switch (type.getObjCLifetime()) {
  case Qualifiers::OCL_None:
  case Qualifiers::OCL_ExplicitNone:
  case Qualifiers::OCL_Autoreleasing:
    break;

  case Qualifiers::OCL_Strong:
    return DK_objc_strong_lifetime;
  case Qualifiers::OCL_Weak:
    return DK_objc_weak_lifetime;
  }

  if (const auto *RT =
          type->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
    const RecordDecl *RD = RT->getDecl();
    if (const auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
      /// Check if this is a C++ object with a non-trivial destructor.
      if (CXXRD->hasDefinition() && !CXXRD->hasTrivialDestructor())
        return DK_cxx_destructor;
    } else {
      /// Check if this is a C struct that is non-trivial to destroy or an array
      /// that contains such a struct.
      if (RD->isNonTrivialToPrimitiveDestroy())
        return DK_nontrivial_c_struct;
    }
  }

  return DK_none;
}

CXXRecordDecl *MemberPointerType::getMostRecentCXXRecordDecl() const {
  return getClass()->getAsCXXRecordDecl()->getMostRecentNonInjectedDecl();
}

void clang::FixedPointValueToString(SmallVectorImpl<char> &Str,
                                    llvm::APSInt Val, unsigned Scale) {
  FixedPointSemantics FXSema(Val.getBitWidth(), Scale, Val.isSigned(),
                             /*IsSaturated=*/false,
                             /*HasUnsignedPadding=*/false);
  APFixedPoint(Val, FXSema).toString(Str);
}

AutoType::AutoType(QualType DeducedAsType, AutoTypeKeyword Keyword,
                   TypeDependence ExtraDependence,
                   ConceptDecl *TypeConstraintConcept,
                   ArrayRef<TemplateArgument> TypeConstraintArgs)
    : DeducedType(Auto, DeducedAsType, ExtraDependence) {
  AutoTypeBits.Keyword = (unsigned)Keyword;
  AutoTypeBits.NumArgs = TypeConstraintArgs.size();
  this->TypeConstraintConcept = TypeConstraintConcept;
  if (TypeConstraintConcept) {
    TemplateArgument *ArgBuffer = getArgBuffer();
    for (const TemplateArgument &Arg : TypeConstraintArgs) {
      addDependence(toTypeDependence(
          Arg.getDependence() & TemplateArgumentDependence::UnexpandedPack));

      new (ArgBuffer++) TemplateArgument(Arg);
    }
  }
}

void AutoType::Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                      QualType Deduced, AutoTypeKeyword Keyword,
                      bool IsDependent, ConceptDecl *CD,
                      ArrayRef<TemplateArgument> Arguments) {
  ID.AddPointer(Deduced.getAsOpaquePtr());
  ID.AddInteger((unsigned)Keyword);
  ID.AddBoolean(IsDependent);
  ID.AddPointer(CD);
  for (const TemplateArgument &Arg : Arguments)
    Arg.Profile(ID, Context);
}