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//======- ParsedAttr.h - Parsed attribute sets ------------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file defines the ParsedAttr class, which is used to collect

// parsed attributes.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_SEMA_PARSEDATTR_H

#define LLVM_CLANG_SEMA_PARSEDATTR_H

#include "clang/Basic/AttrSubjectMatchRules.h"

#include "clang/Basic/AttributeCommonInfo.h"

#include "clang/Basic/Diagnostic.h"

#include "clang/Basic/SourceLocation.h"

#include "clang/Sema/Ownership.h"

#include "llvm/ADT/PointerUnion.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/Support/Allocator.h"

#include "llvm/Support/Registry.h"

#include "llvm/Support/VersionTuple.h"

#include <cassert>

#include <cstddef>

#include <cstring>

#include <utility>

namespace clang {

class ASTContext;

class Decl;

class Expr;

class IdentifierInfo;

class LangOptions;

class ParsedAttr;

class Sema;

class Stmt;

class TargetInfo;

struct ParsedAttrInfo {

  /// Corresponds to the Kind enum.

  unsigned AttrKind : 16;

  /// The number of required arguments of this attribute.

  unsigned NumArgs : 4;

  /// The number of optional arguments of this attributes.

  unsigned OptArgs : 4;

  /// The number of non-fake arguments specified in the attribute definition.

  unsigned NumArgMembers : 4;

  /// True if the parsing does not match the semantic content.

  unsigned HasCustomParsing : 1;

  // True if this attribute accepts expression parameter pack expansions.

  unsigned AcceptsExprPack : 1;

  /// True if this attribute is only available for certain targets.

  unsigned IsTargetSpecific : 1;

  /// True if this attribute applies to types.

  unsigned IsType : 1;

  /// True if this attribute applies to statements.

  unsigned IsStmt : 1;

  /// True if this attribute has any spellings that are known to gcc.

  unsigned IsKnownToGCC : 1;

  /// True if this attribute is supported by #pragma clang attribute.

  unsigned IsSupportedByPragmaAttribute : 1;

  /// The syntaxes supported by this attribute and how they're spelled.

  struct Spelling {

    AttributeCommonInfo::Syntax Syntax;

    const char *NormalizedFullName;

  };

  ArrayRef<Spelling> Spellings;

  // The names of the known arguments of this attribute.

  ArrayRef<const char *> ArgNames;

protected:

  constexpr ParsedAttrInfo(AttributeCommonInfo::Kind AttrKind =

                               AttributeCommonInfo::NoSemaHandlerAttribute)

      : AttrKind(AttrKind), NumArgs(0), OptArgs(0), NumArgMembers(0),

        HasCustomParsing(0), AcceptsExprPack(0), IsTargetSpecific(0), IsType(0),

        IsStmt(0), IsKnownToGCC(0), IsSupportedByPragmaAttribute(0) {}

  constexpr ParsedAttrInfo(AttributeCommonInfo::Kind AttrKind, unsigned NumArgs,

                           unsigned OptArgs, unsigned NumArgMembers,

                           unsigned HasCustomParsing, unsigned AcceptsExprPack,

                           unsigned IsTargetSpecific, unsigned IsType,

                           unsigned IsStmt, unsigned IsKnownToGCC,

                           unsigned IsSupportedByPragmaAttribute,

                           ArrayRef<Spelling> Spellings,

                           ArrayRef<const char *> ArgNames)

      : AttrKind(AttrKind), NumArgs(NumArgs), OptArgs(OptArgs),

        NumArgMembers(NumArgMembers), HasCustomParsing(HasCustomParsing),

        AcceptsExprPack(AcceptsExprPack), IsTargetSpecific(IsTargetSpecific),

        IsType(IsType), IsStmt(IsStmt), IsKnownToGCC(IsKnownToGCC),

        IsSupportedByPragmaAttribute(IsSupportedByPragmaAttribute),

        Spellings(Spellings), ArgNames(ArgNames) {}

public:

  virtual ~ParsedAttrInfo() = default;

  /// Check if this attribute appertains to D, and issue a diagnostic if not.

  virtual bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,

                                    const Decl *D) const {

    return true;

  }

  /// Check if this attribute appertains to St, and issue a diagnostic if not.

  virtual bool diagAppertainsToStmt(Sema &S, const ParsedAttr &Attr,

                                    const Stmt *St) const {

    return true;

  }

  /// Check if the given attribute is mutually exclusive with other attributes

  /// already applied to the given declaration.

  virtual bool diagMutualExclusion(Sema &S, const ParsedAttr &A,

                                   const Decl *D) const {

    return true;

  }

  /// Check if this attribute is allowed by the language we are compiling.

  virtual bool acceptsLangOpts(const LangOptions &LO) const { return true; }

  /// Check if this attribute is allowed when compiling for the given target.

  virtual bool existsInTarget(const TargetInfo &Target) const {

    return true;

  }

  /// Convert the spelling index of Attr to a semantic spelling enum value.

  virtual unsigned

  spellingIndexToSemanticSpelling(const ParsedAttr &Attr) const {

    return UINT_MAX;

  }

  /// Returns true if the specified parameter index for this attribute in

  /// Attr.td is an ExprArgument or VariadicExprArgument, or a subclass thereof;

  /// returns false otherwise.

  virtual bool isParamExpr(size_t N) const { return false; }

  /// Populate Rules with the match rules of this attribute.

  virtual void getPragmaAttributeMatchRules(

      llvm::SmallVectorImpl<std::pair<attr::SubjectMatchRule, bool>> &Rules,

      const LangOptions &LangOpts) const {

  }

  enum AttrHandling {

    NotHandled,

    AttributeApplied,

    AttributeNotApplied

  };

  /// If this ParsedAttrInfo knows how to handle this ParsedAttr applied to this

  /// Decl then do so and return either AttributeApplied if it was applied or

  /// AttributeNotApplied if it wasn't. Otherwise return NotHandled.

  virtual AttrHandling handleDeclAttribute(Sema &S, Decl *D,

                                           const ParsedAttr &Attr) const {

    return NotHandled;

  }

  static const ParsedAttrInfo &get(const AttributeCommonInfo &A);

  static ArrayRef<const ParsedAttrInfo *> getAllBuiltin();

};

typedef llvm::Registry<ParsedAttrInfo> ParsedAttrInfoRegistry;

/// Represents information about a change in availability for

/// an entity, which is part of the encoding of the 'availability'

/// attribute.

struct AvailabilityChange {

  /// The location of the keyword indicating the kind of change.

  SourceLocation KeywordLoc;

  /// The version number at which the change occurred.

  VersionTuple Version;

  /// The source range covering the version number.

  SourceRange VersionRange;

  /// Determine whether this availability change is valid.

  bool isValid() const { return !Version.empty(); }

};

namespace detail {

enum AvailabilitySlot {

  IntroducedSlot, DeprecatedSlot, ObsoletedSlot, NumAvailabilitySlots

};

/// Describes the trailing object for Availability attribute in ParsedAttr.

struct AvailabilityData {

  AvailabilityChange Changes[NumAvailabilitySlots];

  SourceLocation StrictLoc;

  const Expr *Replacement;

  AvailabilityData(const AvailabilityChange &Introduced,

                   const AvailabilityChange &Deprecated,

                   const AvailabilityChange &Obsoleted,

                   SourceLocation Strict, const Expr *ReplaceExpr)

    : StrictLoc(Strict), Replacement(ReplaceExpr) {

    Changes[IntroducedSlot] = Introduced;

    Changes[DeprecatedSlot] = Deprecated;

    Changes[ObsoletedSlot] = Obsoleted;

  }

};

struct TypeTagForDatatypeData {

  ParsedType MatchingCType;

  unsigned LayoutCompatible : 1;

  unsigned MustBeNull : 1;

};

struct PropertyData {

  IdentifierInfo *GetterId, *SetterId;

  PropertyData(IdentifierInfo *getterId, IdentifierInfo *setterId)

      : GetterId(getterId), SetterId(setterId) {}

};

} // namespace

/// Wraps an identifier and optional source location for the identifier.

struct IdentifierLoc {

  SourceLocation Loc;

  IdentifierInfo *Ident;

  static IdentifierLoc *create(ASTContext &Ctx, SourceLocation Loc,

                               IdentifierInfo *Ident);

};

/// A union of the various pointer types that can be passed to an

/// ParsedAttr as an argument.

using ArgsUnion = llvm::PointerUnion<Expr *, IdentifierLoc *>;

using ArgsVector = llvm::SmallVector<ArgsUnion, 12U>;

/// ParsedAttr - Represents a syntactic attribute.

///

/// For a GNU attribute, there are four forms of this construct:

///

/// 1: __attribute__(( const )). ParmName/Args/NumArgs will all be unused.

/// 2: __attribute__(( mode(byte) )). ParmName used, Args/NumArgs unused.

/// 3: __attribute__(( format(printf, 1, 2) )). ParmName/Args/NumArgs all used.

/// 4: __attribute__(( aligned(16) )). ParmName is unused, Args/Num used.

///

class ParsedAttr final

    : public AttributeCommonInfo,

      private llvm::TrailingObjects<

          ParsedAttr, ArgsUnion, detail::AvailabilityData,

          detail::TypeTagForDatatypeData, ParsedType, detail::PropertyData> {

  friend TrailingObjects;

  size_t numTrailingObjects(OverloadToken<ArgsUnion>) const { return NumArgs; }

  size_t numTrailingObjects(OverloadToken<detail::AvailabilityData>) const {

    return IsAvailability;

  }

  size_t

      numTrailingObjects(OverloadToken<detail::TypeTagForDatatypeData>) const {

    return IsTypeTagForDatatype;

  }

  size_t numTrailingObjects(OverloadToken<ParsedType>) const {

    return HasParsedType;

  }

  size_t numTrailingObjects(OverloadToken<detail::PropertyData>) const {

    return IsProperty;

  }

private:

  IdentifierInfo *MacroII = nullptr;

  SourceLocation MacroExpansionLoc;

  SourceLocation EllipsisLoc;

  /// The number of expression arguments this attribute has.

  /// The expressions themselves are stored after the object.

  unsigned NumArgs : 16;

  /// True if already diagnosed as invalid.

  mutable unsigned Invalid : 1;

  /// True if this attribute was used as a type attribute.

  mutable unsigned UsedAsTypeAttr : 1;

  /// True if this has the extra information associated with an

  /// availability attribute.

  unsigned IsAvailability : 1;

  /// True if this has extra information associated with a

  /// type_tag_for_datatype attribute.

  unsigned IsTypeTagForDatatype : 1;

  /// True if this has extra information associated with a

  /// Microsoft __delcspec(property) attribute.

  unsigned IsProperty : 1;

  /// True if this has a ParsedType

  unsigned HasParsedType : 1;

  /// True if the processing cache is valid.

  mutable unsigned HasProcessingCache : 1;

  /// A cached value.

  mutable unsigned ProcessingCache : 8;

  /// True if the attribute is specified using '#pragma clang attribute'.

  mutable unsigned IsPragmaClangAttribute : 1;

  /// The location of the 'unavailable' keyword in an

  /// availability attribute.

  SourceLocation UnavailableLoc;

  const Expr *MessageExpr;

  const ParsedAttrInfo &Info;

  ArgsUnion *getArgsBuffer() { return getTrailingObjects<ArgsUnion>(); }

  ArgsUnion const *getArgsBuffer() const {

    return getTrailingObjects<ArgsUnion>();

  }

  detail::AvailabilityData *getAvailabilityData() {

    return getTrailingObjects<detail::AvailabilityData>();

  }

  const detail::AvailabilityData *getAvailabilityData() const {

    return getTrailingObjects<detail::AvailabilityData>();

  }

private:

  friend class AttributeFactory;

  friend class AttributePool;

  /// Constructor for attributes with expression arguments.

  ParsedAttr(IdentifierInfo *attrName, SourceRange attrRange,

             IdentifierInfo *scopeName, SourceLocation scopeLoc,

             ArgsUnion *args, unsigned numArgs, Syntax syntaxUsed,

             SourceLocation ellipsisLoc)

      : AttributeCommonInfo(attrName, scopeName, attrRange, scopeLoc,

                            syntaxUsed),

        EllipsisLoc(ellipsisLoc), NumArgs(numArgs), Invalid(false),

        UsedAsTypeAttr(false), IsAvailability(false),

        IsTypeTagForDatatype(false), IsProperty(false), HasParsedType(false),

        HasProcessingCache(false), IsPragmaClangAttribute(false),

        Info(ParsedAttrInfo::get(*this)) {

    if (numArgs)

      memcpy(getArgsBuffer(), args, numArgs * sizeof(ArgsUnion));

  }

  /// Constructor for availability attributes.

  ParsedAttr(IdentifierInfo *attrName, SourceRange attrRange,

             IdentifierInfo *scopeName, SourceLocation scopeLoc,

             IdentifierLoc *Parm, const AvailabilityChange &introduced,

             const AvailabilityChange &deprecated,

             const AvailabilityChange &obsoleted, SourceLocation unavailable,

             const Expr *messageExpr, Syntax syntaxUsed, SourceLocation strict,

             const Expr *replacementExpr)

      : AttributeCommonInfo(attrName, scopeName, attrRange, scopeLoc,

                            syntaxUsed),

        NumArgs(1), Invalid(false), UsedAsTypeAttr(false), IsAvailability(true),

        IsTypeTagForDatatype(false), IsProperty(false), HasParsedType(false),

        HasProcessingCache(false), IsPragmaClangAttribute(false),

        UnavailableLoc(unavailable), MessageExpr(messageExpr),

        Info(ParsedAttrInfo::get(*this)) {

    ArgsUnion PVal(Parm);

    memcpy(getArgsBuffer(), &PVal, sizeof(ArgsUnion));

    new (getAvailabilityData()) detail::AvailabilityData(

        introduced, deprecated, obsoleted, strict, replacementExpr);

  }

  /// Constructor for objc_bridge_related attributes.

  ParsedAttr(IdentifierInfo *attrName, SourceRange attrRange,

             IdentifierInfo *scopeName, SourceLocation scopeLoc,

             IdentifierLoc *Parm1, IdentifierLoc *Parm2, IdentifierLoc *Parm3,

             Syntax syntaxUsed)

      : AttributeCommonInfo(attrName, scopeName, attrRange, scopeLoc,

                            syntaxUsed),

        NumArgs(3), Invalid(false), UsedAsTypeAttr(false),

        IsAvailability(false), IsTypeTagForDatatype(false), IsProperty(false),

        HasParsedType(false), HasProcessingCache(false),

        IsPragmaClangAttribute(false), Info(ParsedAttrInfo::get(*this)) {

    ArgsUnion *Args = getArgsBuffer();

    Args[0] = Parm1;

    Args[1] = Parm2;

    Args[2] = Parm3;

  }

  /// Constructor for type_tag_for_datatype attribute.

  ParsedAttr(IdentifierInfo *attrName, SourceRange attrRange,

             IdentifierInfo *scopeName, SourceLocation scopeLoc,

             IdentifierLoc *ArgKind, ParsedType matchingCType,

             bool layoutCompatible, bool mustBeNull, Syntax syntaxUsed)

      : AttributeCommonInfo(attrName, scopeName, attrRange, scopeLoc,

                            syntaxUsed),

        NumArgs(1), Invalid(false), UsedAsTypeAttr(false),

        IsAvailability(false), IsTypeTagForDatatype(true), IsProperty(false),

        HasParsedType(false), HasProcessingCache(false),

        IsPragmaClangAttribute(false), Info(ParsedAttrInfo::get(*this)) {

    ArgsUnion PVal(ArgKind);

    memcpy(getArgsBuffer(), &PVal, sizeof(ArgsUnion));

    detail::TypeTagForDatatypeData &ExtraData = getTypeTagForDatatypeDataSlot();

    new (&ExtraData.MatchingCType) ParsedType(matchingCType);

    ExtraData.LayoutCompatible = layoutCompatible;

    ExtraData.MustBeNull = mustBeNull;

  }

  /// Constructor for attributes with a single type argument.

  ParsedAttr(IdentifierInfo *attrName, SourceRange attrRange,

             IdentifierInfo *scopeName, SourceLocation scopeLoc,

             ParsedType typeArg, Syntax syntaxUsed)

      : AttributeCommonInfo(attrName, scopeName, attrRange, scopeLoc,

                            syntaxUsed),

        NumArgs(0), Invalid(false), UsedAsTypeAttr(false),

        IsAvailability(false), IsTypeTagForDatatype(false), IsProperty(false),

        HasParsedType(true), HasProcessingCache(false),

        IsPragmaClangAttribute(false), Info(ParsedAttrInfo::get(*this)) {

    new (&getTypeBuffer()) ParsedType(typeArg);

  }

  /// Constructor for microsoft __declspec(property) attribute.

  ParsedAttr(IdentifierInfo *attrName, SourceRange attrRange,

             IdentifierInfo *scopeName, SourceLocation scopeLoc,

             IdentifierInfo *getterId, IdentifierInfo *setterId,

             Syntax syntaxUsed)

      : AttributeCommonInfo(attrName, scopeName, attrRange, scopeLoc,

                            syntaxUsed),

        NumArgs(0), Invalid(false), UsedAsTypeAttr(false),

        IsAvailability(false), IsTypeTagForDatatype(false), IsProperty(true),

        HasParsedType(false), HasProcessingCache(false),

        IsPragmaClangAttribute(false), Info(ParsedAttrInfo::get(*this)) {

    new (&getPropertyDataBuffer()) detail::PropertyData(getterId, setterId);

  }

  /// Type tag information is stored immediately following the arguments, if

  /// any, at the end of the object.  They are mutually exclusive with

  /// availability slots.

  detail::TypeTagForDatatypeData &getTypeTagForDatatypeDataSlot() {

    return *getTrailingObjects<detail::TypeTagForDatatypeData>();

  }

  const detail::TypeTagForDatatypeData &getTypeTagForDatatypeDataSlot() const {

    return *getTrailingObjects<detail::TypeTagForDatatypeData>();

  }

  /// The type buffer immediately follows the object and are mutually exclusive

  /// with arguments.

  ParsedType &getTypeBuffer() { return *getTrailingObjects<ParsedType>(); }

  const ParsedType &getTypeBuffer() const {

    return *getTrailingObjects<ParsedType>();

  }

  /// The property data immediately follows the object is mutually exclusive

  /// with arguments.

  detail::PropertyData &getPropertyDataBuffer() {

    assert(IsProperty);

    return *getTrailingObjects<detail::PropertyData>();

  }

  const detail::PropertyData &getPropertyDataBuffer() const {

    assert(IsProperty);

    return *getTrailingObjects<detail::PropertyData>();

  }

  size_t allocated_size() const;

public:

  ParsedAttr(const ParsedAttr &) = delete;

  ParsedAttr(ParsedAttr &&) = delete;

  ParsedAttr &operator=(const ParsedAttr &) = delete;

  ParsedAttr &operator=(ParsedAttr &&) = delete;

  ~ParsedAttr() = delete;

  void operator delete(void *) = delete;

  bool hasParsedType() const { return HasParsedType; }

  /// Is this the Microsoft __declspec(property) attribute?

  bool isDeclspecPropertyAttribute() const  {

    return IsProperty;

  }

  bool isInvalid() const { return Invalid; }

  void setInvalid(bool b = true) const { Invalid = b; }

  bool hasProcessingCache() const { return HasProcessingCache; }

  unsigned getProcessingCache() const {

    assert(hasProcessingCache());

    return ProcessingCache;

  }

  void setProcessingCache(unsigned value) const {

    ProcessingCache = value;

    HasProcessingCache = true;

  }

  bool isUsedAsTypeAttr() const { return UsedAsTypeAttr; }

  void setUsedAsTypeAttr(bool Used = true) { UsedAsTypeAttr = Used; }

  /// True if the attribute is specified using '#pragma clang attribute'.

  bool isPragmaClangAttribute() const { return IsPragmaClangAttribute; }

  void setIsPragmaClangAttribute() { IsPragmaClangAttribute = true; }

  bool isPackExpansion() const { return EllipsisLoc.isValid(); }

  SourceLocation getEllipsisLoc() const { return EllipsisLoc; }

  /// getNumArgs - Return the number of actual arguments to this attribute.

  unsigned getNumArgs() const { return NumArgs; }

  /// getArg - Return the specified argument.

  ArgsUnion getArg(unsigned Arg) const {

    assert(Arg < NumArgs && "Arg access out of range!");

    return getArgsBuffer()[Arg];

  }

  bool isArgExpr(unsigned Arg) const {

    return Arg < NumArgs && getArg(Arg).is<Expr*>();

  }

  Expr *getArgAsExpr(unsigned Arg) const {

    return getArg(Arg).get<Expr*>();

  }

  bool isArgIdent(unsigned Arg) const {

    return Arg < NumArgs && getArg(Arg).is<IdentifierLoc*>();

  }

  IdentifierLoc *getArgAsIdent(unsigned Arg) const {

    return getArg(Arg).get<IdentifierLoc*>();

  }

  const AvailabilityChange &getAvailabilityIntroduced() const {

    assert(getParsedKind() == AT_Availability &&

           "Not an availability attribute");

    return getAvailabilityData()->Changes[detail::IntroducedSlot];

  }

  const AvailabilityChange &getAvailabilityDeprecated() const {

    assert(getParsedKind() == AT_Availability &&

           "Not an availability attribute");

    return getAvailabilityData()->Changes[detail::DeprecatedSlot];

  }

  const AvailabilityChange &getAvailabilityObsoleted() const {

    assert(getParsedKind() == AT_Availability &&

           "Not an availability attribute");

    return getAvailabilityData()->Changes[detail::ObsoletedSlot];

  }

  SourceLocation getStrictLoc() const {

    assert(getParsedKind() == AT_Availability &&

           "Not an availability attribute");

    return getAvailabilityData()->StrictLoc;

  }

  SourceLocation getUnavailableLoc() const {

    assert(getParsedKind() == AT_Availability &&

           "Not an availability attribute");

    return UnavailableLoc;

  }

  const Expr * getMessageExpr() const {

    assert(getParsedKind() == AT_Availability &&

           "Not an availability attribute");

    return MessageExpr;

  }

  const Expr *getReplacementExpr() const {

    assert(getParsedKind() == AT_Availability &&

           "Not an availability attribute");

    return getAvailabilityData()->Replacement;

  }

  const ParsedType &getMatchingCType() const {

    assert(getParsedKind() == AT_TypeTagForDatatype &&

           "Not a type_tag_for_datatype attribute");

    return getTypeTagForDatatypeDataSlot().MatchingCType;

  }

  bool getLayoutCompatible() const {

    assert(getParsedKind() == AT_TypeTagForDatatype &&

           "Not a type_tag_for_datatype attribute");

    return getTypeTagForDatatypeDataSlot().LayoutCompatible;

  }

  bool getMustBeNull() const {

    assert(getParsedKind() == AT_TypeTagForDatatype &&

           "Not a type_tag_for_datatype attribute");

    return getTypeTagForDatatypeDataSlot().MustBeNull;

  }

  const ParsedType &getTypeArg() const {

    assert(HasParsedType && "Not a type attribute");

    return getTypeBuffer();

  }

  IdentifierInfo *getPropertyDataGetter() const {

    assert(isDeclspecPropertyAttribute() &&

           "Not a __delcspec(property) attribute");

    return getPropertyDataBuffer().GetterId;

  }

  IdentifierInfo *getPropertyDataSetter() const {

    assert(isDeclspecPropertyAttribute() &&

           "Not a __delcspec(property) attribute");

    return getPropertyDataBuffer().SetterId;

  }

  /// Set the macro identifier info object that this parsed attribute was

  /// declared in if it was declared in a macro. Also set the expansion location

  /// of the macro.

  void setMacroIdentifier(IdentifierInfo *MacroName, SourceLocation Loc) {

    MacroII = MacroName;

    MacroExpansionLoc = Loc;

  }

  /// Returns true if this attribute was declared in a macro.

  bool hasMacroIdentifier() const { return MacroII != nullptr; }

  /// Return the macro identifier if this attribute was declared in a macro.

  /// nullptr is returned if it was not declared in a macro.

  IdentifierInfo *getMacroIdentifier() const { return MacroII; }

  SourceLocation getMacroExpansionLoc() const {

    assert(hasMacroIdentifier() && "Can only get the macro expansion location "

                                   "if this attribute has a macro identifier.");

    return MacroExpansionLoc;

  }

  /// Check if the attribute has exactly as many args as Num. May output an

  /// error. Returns false if a diagnostic is produced.

  bool checkExactlyNumArgs(class Sema &S, unsigned Num) const;

  /// Check if the attribute has at least as many args as Num. May output an

  /// error. Returns false if a diagnostic is produced.

  bool checkAtLeastNumArgs(class Sema &S, unsigned Num) const;

  /// Check if the attribute has at most as many args as Num. May output an

  /// error. Returns false if a diagnostic is produced.

  bool checkAtMostNumArgs(class Sema &S, unsigned Num) const;

  bool isTargetSpecificAttr() const;

  bool isTypeAttr() const;

  bool isStmtAttr() const;

  bool hasCustomParsing() const;

  bool acceptsExprPack() const;

  bool isParamExpr(size_t N) const;

  unsigned getMinArgs() const;

  unsigned getMaxArgs() const;

  unsigned getNumArgMembers() const;

  bool hasVariadicArg() const;

  void handleAttrWithDelayedArgs(Sema &S, Decl *D) const;

  bool diagnoseAppertainsTo(class Sema &S, const Decl *D) const;

  bool diagnoseAppertainsTo(class Sema &S, const Stmt *St) const;

  bool diagnoseMutualExclusion(class Sema &S, const Decl *D) const;

  // This function stub exists for parity with the declaration checking code so

  // that checkCommonAttributeFeatures() can work generically on declarations

  // or statements.

  bool diagnoseMutualExclusion(class Sema &S, const Stmt *St) const {

    return true;

  }

  bool appliesToDecl(const Decl *D, attr::SubjectMatchRule MatchRule) const;

  void getMatchRules(const LangOptions &LangOpts,

                     SmallVectorImpl<std::pair<attr::SubjectMatchRule, bool>>

                         &MatchRules) const;

  bool diagnoseLangOpts(class Sema &S) const;

  bool existsInTarget(const TargetInfo &Target) const;

  bool isKnownToGCC() const;

  bool isSupportedByPragmaAttribute() const;

  /// Returns whether a [[]] attribute, if specified ahead of a declaration,

  /// should be applied to the decl-specifier-seq instead (i.e. whether it

  /// "slides" to the decl-specifier-seq).

  ///

  /// By the standard, attributes specified before the declaration always

  /// appertain to the declaration, but historically we have allowed some of

  /// these attributes to slide to the decl-specifier-seq, so we need to keep

  /// supporting this behavior.

  ///

  /// This may only be called if isStandardAttributeSyntax() returns true.

  bool slidesFromDeclToDeclSpecLegacyBehavior() const;

  /// If the parsed attribute has a semantic equivalent, and it would

  /// have a semantic Spelling enumeration (due to having semantically-distinct

  /// spelling variations), return the value of that semantic spelling. If the

  /// parsed attribute does not have a semantic equivalent, or would not have

  /// a Spelling enumeration, the value UINT_MAX is returned.

  unsigned getSemanticSpelling() const;

  /// If this is an OpenCL address space attribute, returns its representation

  /// in LangAS, otherwise returns default address space.

  LangAS asOpenCLLangAS() const {

    switch (getParsedKind()) {

    case ParsedAttr::AT_OpenCLConstantAddressSpace:

      return LangAS::opencl_constant;

    case ParsedAttr::AT_OpenCLGlobalAddressSpace:

      return LangAS::opencl_global;

    case ParsedAttr::AT_OpenCLGlobalDeviceAddressSpace:

      return LangAS::opencl_global_device;

    case ParsedAttr::AT_OpenCLGlobalHostAddressSpace:

      return LangAS::opencl_global_host;

    case ParsedAttr::AT_OpenCLLocalAddressSpace:

      return LangAS::opencl_local;

    case ParsedAttr::AT_OpenCLPrivateAddressSpace:

      return LangAS::opencl_private;

    case ParsedAttr::AT_OpenCLGenericAddressSpace:

      return LangAS::opencl_generic;

    default:

      return LangAS::Default;

    }

  }

  /// If this is an OpenCL address space attribute, returns its SYCL

  /// representation in LangAS, otherwise returns default address space.

  LangAS asSYCLLangAS() const {

    switch (getKind()) {

    case ParsedAttr::AT_OpenCLGlobalAddressSpace:

      return LangAS::sycl_global;

    case ParsedAttr::AT_OpenCLGlobalDeviceAddressSpace:

      return LangAS::sycl_global_device;

    case ParsedAttr::AT_OpenCLGlobalHostAddressSpace:

      return LangAS::sycl_global_host;

    case ParsedAttr::AT_OpenCLLocalAddressSpace:

      return LangAS::sycl_local;

    case ParsedAttr::AT_OpenCLPrivateAddressSpace:

      return LangAS::sycl_private;

    case ParsedAttr::AT_OpenCLGenericAddressSpace:

    default:

      return LangAS::Default;

    }

  }

  /// If this is an HLSL address space attribute, returns its representation

  /// in LangAS, otherwise returns default address space.

  LangAS asHLSLLangAS() const {

    switch (getParsedKind()) {

    case ParsedAttr::AT_HLSLGroupSharedAddressSpace:

      return LangAS::hlsl_groupshared;

    default:

      return LangAS::Default;

    }

  }

  AttributeCommonInfo::Kind getKind() const {

    return AttributeCommonInfo::Kind(Info.AttrKind);

  }

  const ParsedAttrInfo &getInfo() const { return Info; }

};

class AttributePool;

/// A factory, from which one makes pools, from which one creates

/// individual attributes which are deallocated with the pool.

///

/// Note that it's tolerably cheap to create and destroy one of

/// these as long as you don't actually allocate anything in it.

class AttributeFactory {

public:

  enum {

    AvailabilityAllocSize =

        ParsedAttr::totalSizeToAlloc<ArgsUnion, detail::AvailabilityData,

                                     detail::TypeTagForDatatypeData, ParsedType,

                                     detail::PropertyData>(1, 1, 0, 0, 0),

    TypeTagForDatatypeAllocSize =

        ParsedAttr::totalSizeToAlloc<ArgsUnion, detail::AvailabilityData,

                                     detail::TypeTagForDatatypeData, ParsedType,

                                     detail::PropertyData>(1, 0, 1, 0, 0),

    PropertyAllocSize =

        ParsedAttr::totalSizeToAlloc<ArgsUnion, detail::AvailabilityData,

                                     detail::TypeTagForDatatypeData, ParsedType,

                                     detail::PropertyData>(0, 0, 0, 0, 1),

  };

private:

  enum {

    /// The number of free lists we want to be sure to support

    /// inline.  This is just enough that availability attributes

    /// don't surpass it.  It's actually very unlikely we'll see an

    /// attribute that needs more than that; on x86-64 you'd need 10

    /// expression arguments, and on i386 you'd need 19.

    InlineFreeListsCapacity =

        1 + (AvailabilityAllocSize - sizeof(ParsedAttr)) / sizeof(void *)

  };

  llvm::BumpPtrAllocator Alloc;

  /// Free lists.  The index is determined by the following formula:

  ///   (size - sizeof(ParsedAttr)) / sizeof(void*)

  SmallVector<SmallVector<ParsedAttr *, 8>, InlineFreeListsCapacity> FreeLists;

  // The following are the private interface used by AttributePool.

  friend class AttributePool;

  /// Allocate an attribute of the given size.

  void *allocate(size_t size);

  void deallocate(ParsedAttr *AL);

  /// Reclaim all the attributes in the given pool chain, which is

  /// non-empty.  Note that the current implementation is safe

  /// against reclaiming things which were not actually allocated

  /// with the allocator, although of course it's important to make

  /// sure that their allocator lives at least as long as this one.

  void reclaimPool(AttributePool &head);

public:

  AttributeFactory();