SemaDeclAttr.cpp

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//===--- SemaDeclAttr.cpp - Declaration Attribute Handling ----------------===//
//
// 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 decl-related attribute processing.
//
//===----------------------------------------------------------------------===//
 
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTMutationListener.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/Mangle.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/Type.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Basic/DarwinSDKInfo.h"
#include "clang/Basic/HLSLRuntime.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetBuiltins.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/DelayedDiagnostic.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedAttr.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/Assumptions.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <optional>
 
using namespace clang;
using namespace sema;
 
namespace AttributeLangSupport {
  enum LANG {
    C,
    Cpp,
    ObjC
  };
} // end namespace AttributeLangSupport
 
//===----------------------------------------------------------------------===//
//  Helper functions
//===----------------------------------------------------------------------===//
 
/// isFunctionOrMethod - Return true if the given decl has function
/// type (function or function-typed variable) or an Objective-C
/// method.
static bool isFunctionOrMethod(const Decl *D) {
  return (D->getFunctionType() != nullptr) || isa<ObjCMethodDecl>(D);
}
 
/// Return true if the given decl has function type (function or
/// function-typed variable) or an Objective-C method or a block.
static bool isFunctionOrMethodOrBlock(const Decl *D) {
  return isFunctionOrMethod(D) || isa<BlockDecl>(D);
}
 
/// Return true if the given decl has a declarator that should have
/// been processed by Sema::GetTypeForDeclarator.
static bool hasDeclarator(const Decl *D) {
  // In some sense, TypedefDecl really *ought* to be a DeclaratorDecl.
  return isa<DeclaratorDecl>(D) || isa<BlockDecl>(D) || isa<TypedefNameDecl>(D) ||
         isa<ObjCPropertyDecl>(D);
}
 
/// hasFunctionProto - Return true if the given decl has a argument
/// information. This decl should have already passed
/// isFunctionOrMethod or isFunctionOrMethodOrBlock.
static bool hasFunctionProto(const Decl *D) {
  if (const FunctionType *FnTy = D->getFunctionType())
    return isa<FunctionProtoType>(FnTy);
  return isa<ObjCMethodDecl>(D) || isa<BlockDecl>(D);
}
 
/// getFunctionOrMethodNumParams - Return number of function or method
/// parameters. It is an error to call this on a K&R function (use
/// hasFunctionProto first).
static unsigned getFunctionOrMethodNumParams(const Decl *D) {
  if (const FunctionType *FnTy = D->getFunctionType())
    return cast<FunctionProtoType>(FnTy)->getNumParams();
  if (const auto *BD = dyn_cast<BlockDecl>(D))
    return BD->getNumParams();
  return cast<ObjCMethodDecl>(D)->param_size();
}
 
static const ParmVarDecl *getFunctionOrMethodParam(const Decl *D,
                                                   unsigned Idx) {
  if (const auto *FD = dyn_cast<FunctionDecl>(D))
    return FD->getParamDecl(Idx);
  if (const auto *MD = dyn_cast<ObjCMethodDecl>(D))
    return MD->getParamDecl(Idx);
  if (const auto *BD = dyn_cast<BlockDecl>(D))
    return BD->getParamDecl(Idx);
  return nullptr;
}
 
static QualType getFunctionOrMethodParamType(const Decl *D, unsigned Idx) {
  if (const FunctionType *FnTy = D->getFunctionType())
    return cast<FunctionProtoType>(FnTy)->getParamType(Idx);
  if (const auto *BD = dyn_cast<BlockDecl>(D))
    return BD->getParamDecl(Idx)->getType();
 
  return cast<ObjCMethodDecl>(D)->parameters()[Idx]->getType();
}
 
static SourceRange getFunctionOrMethodParamRange(const Decl *D, unsigned Idx) {
  if (auto *PVD = getFunctionOrMethodParam(D, Idx))
    return PVD->getSourceRange();
  return SourceRange();
}
 
static QualType getFunctionOrMethodResultType(const Decl *D) {
  if (const FunctionType *FnTy = D->getFunctionType())
    return FnTy->getReturnType();
  return cast<ObjCMethodDecl>(D)->getReturnType();
}
 
static SourceRange getFunctionOrMethodResultSourceRange(const Decl *D) {
  if (const auto *FD = dyn_cast<FunctionDecl>(D))
    return FD->getReturnTypeSourceRange();
  if (const auto *MD = dyn_cast<ObjCMethodDecl>(D))
    return MD->getReturnTypeSourceRange();
  return SourceRange();
}
 
static bool isFunctionOrMethodVariadic(const Decl *D) {
  if (const FunctionType *FnTy = D->getFunctionType())
    return cast<FunctionProtoType>(FnTy)->isVariadic();
  if (const auto *BD = dyn_cast<BlockDecl>(D))
    return BD->isVariadic();
  return cast<ObjCMethodDecl>(D)->isVariadic();
}
 
static bool isInstanceMethod(const Decl *D) {
  if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(D))
    return MethodDecl->isInstance();
  return false;
}
 
static inline bool isNSStringType(QualType T, ASTContext &Ctx,
                                  bool AllowNSAttributedString = false) {
  const auto *PT = T->getAs<ObjCObjectPointerType>();
  if (!PT)
    return false;
 
  ObjCInterfaceDecl *Cls = PT->getObjectType()->getInterface();
  if (!Cls)
    return false;
 
  IdentifierInfo* ClsName = Cls->getIdentifier();
 
  if (AllowNSAttributedString &&
      ClsName == &Ctx.Idents.get("NSAttributedString"))
    return true;
  // FIXME: Should we walk the chain of classes?
  return ClsName == &Ctx.Idents.get("NSString") ||
         ClsName == &Ctx.Idents.get("NSMutableString");
}
 
static inline bool isCFStringType(QualType T, ASTContext &Ctx) {
  const auto *PT = T->getAs<PointerType>();
  if (!PT)
    return false;
 
  const auto *RT = PT->getPointeeType()->getAs<RecordType>();
  if (!RT)
    return false;
 
  const RecordDecl *RD = RT->getDecl();
  if (RD->getTagKind() != TTK_Struct)
    return false;
 
  return RD->getIdentifier() == &Ctx.Idents.get("__CFString");
}
 
static unsigned getNumAttributeArgs(const ParsedAttr &AL) {
  // FIXME: Include the type in the argument list.
  return AL.getNumArgs() + AL.hasParsedType();
}
 
/// A helper function to provide Attribute Location for the Attr types
/// AND the ParsedAttr.
template <typename AttrInfo>
static std::enable_if_t<std::is_base_of_v<Attr, AttrInfo>, SourceLocation>
getAttrLoc(const AttrInfo &AL) {
  return AL.getLocation();
}
static SourceLocation getAttrLoc(const ParsedAttr &AL) { return AL.getLoc(); }
 
/// If Expr is a valid integer constant, get the value of the integer
/// expression and return success or failure. May output an error.
///
/// Negative argument is implicitly converted to unsigned, unless
/// \p StrictlyUnsigned is true.
template <typename AttrInfo>
static bool checkUInt32Argument(Sema &S, const AttrInfo &AI, const Expr *Expr,
                                uint32_t &Val, unsigned Idx = UINT_MAX,
                                bool StrictlyUnsigned = false) {
  std::optional<llvm::APSInt> I = llvm::APSInt(32);
  if (Expr->isTypeDependent() ||
      !(I = Expr->getIntegerConstantExpr(S.Context))) {
    if (Idx != UINT_MAX)
      S.Diag(getAttrLoc(AI), diag::err_attribute_argument_n_type)
          << &AI << Idx << AANT_ArgumentIntegerConstant
          << Expr->getSourceRange();
    else
      S.Diag(getAttrLoc(AI), diag::err_attribute_argument_type)
          << &AI << AANT_ArgumentIntegerConstant << Expr->getSourceRange();
    return false;
  }
 
  if (!I->isIntN(32)) {
    S.Diag(Expr->getExprLoc(), diag::err_ice_too_large)
        << toString(*I, 10, false) << 32 << /* Unsigned */ 1;
    return false;
  }
 
  if (StrictlyUnsigned && I->isSigned() && I->isNegative()) {
    S.Diag(getAttrLoc(AI), diag::err_attribute_requires_positive_integer)
        << &AI << /*non-negative*/ 1;
    return false;
  }
 
  Val = (uint32_t)I->getZExtValue();
  return true;
}
 
/// Wrapper around checkUInt32Argument, with an extra check to be sure
/// that the result will fit into a regular (signed) int. All args have the same
/// purpose as they do in checkUInt32Argument.
template <typename AttrInfo>
static bool checkPositiveIntArgument(Sema &S, const AttrInfo &AI, const Expr *Expr,
                                     int &Val, unsigned Idx = UINT_MAX) {
  uint32_t UVal;
  if (!checkUInt32Argument(S, AI, Expr, UVal, Idx))
    return false;
 
  if (UVal > (uint32_t)std::numeric_limits<int>::max()) {
    llvm::APSInt I(32); // for toString
    I = UVal;
    S.Diag(Expr->getExprLoc(), diag::err_ice_too_large)
        << toString(I, 10, false) << 32 << /* Unsigned */ 0;
    return false;
  }
 
  Val = UVal;
  return true;
}
 
/// Diagnose mutually exclusive attributes when present on a given
/// declaration. Returns true if diagnosed.
template <typename AttrTy>
static bool checkAttrMutualExclusion(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (const auto *A = D->getAttr<AttrTy>()) {
    S.Diag(AL.getLoc(), diag::err_attributes_are_not_compatible) << AL << A;
    S.Diag(A->getLocation(), diag::note_conflicting_attribute);
    return true;
  }
  return false;
}
 
template <typename AttrTy>
static bool checkAttrMutualExclusion(Sema &S, Decl *D, const Attr &AL) {
  if (const auto *A = D->getAttr<AttrTy>()) {
    S.Diag(AL.getLocation(), diag::err_attributes_are_not_compatible) << &AL
                                                                      << A;
    S.Diag(A->getLocation(), diag::note_conflicting_attribute);
    return true;
  }
  return false;
}
 
/// Check if IdxExpr is a valid parameter index for a function or
/// instance method D.  May output an error.
///
/// \returns true if IdxExpr is a valid index.
template <typename AttrInfo>
static bool checkFunctionOrMethodParameterIndex(
    Sema &S, const Decl *D, const AttrInfo &AI, unsigned AttrArgNum,
    const Expr *IdxExpr, ParamIdx &Idx, bool CanIndexImplicitThis = false) {
  assert(isFunctionOrMethodOrBlock(D));
 
  // In C++ the implicit 'this' function parameter also counts.
  // Parameters are counted from one.
  bool HP = hasFunctionProto(D);
  bool HasImplicitThisParam = isInstanceMethod(D);
  bool IV = HP && isFunctionOrMethodVariadic(D);
  unsigned NumParams =
      (HP ? getFunctionOrMethodNumParams(D) : 0) + HasImplicitThisParam;
 
  std::optional<llvm::APSInt> IdxInt;
  if (IdxExpr->isTypeDependent() ||
      !(IdxInt = IdxExpr->getIntegerConstantExpr(S.Context))) {
    S.Diag(getAttrLoc(AI), diag::err_attribute_argument_n_type)
        << &AI << AttrArgNum << AANT_ArgumentIntegerConstant
        << IdxExpr->getSourceRange();
    return false;
  }
 
  unsigned IdxSource = IdxInt->getLimitedValue(UINT_MAX);
  if (IdxSource < 1 || (!IV && IdxSource > NumParams)) {
    S.Diag(getAttrLoc(AI), diag::err_attribute_argument_out_of_bounds)
        << &AI << AttrArgNum << IdxExpr->getSourceRange();
    return false;
  }
  if (HasImplicitThisParam && !CanIndexImplicitThis) {
    if (IdxSource == 1) {
      S.Diag(getAttrLoc(AI), diag::err_attribute_invalid_implicit_this_argument)
          << &AI << IdxExpr->getSourceRange();
      return false;
    }
  }
 
  Idx = ParamIdx(IdxSource, D);
  return true;
}
 
/// Check if the argument \p E is a ASCII string literal. If not emit an error
/// and return false, otherwise set \p Str to the value of the string literal
/// and return true.
bool Sema::checkStringLiteralArgumentAttr(const AttributeCommonInfo &CI,
                                          const Expr *E, StringRef &Str,
                                          SourceLocation *ArgLocation) {
  const auto *Literal = dyn_cast<StringLiteral>(E->IgnoreParenCasts());
  if (ArgLocation)
    *ArgLocation = E->getBeginLoc();
 
  if (!Literal || !Literal->isOrdinary()) {
    Diag(E->getBeginLoc(), diag::err_attribute_argument_type)
        << CI << AANT_ArgumentString;
    return false;
  }
 
  Str = Literal->getString();
  return true;
}
 
/// Check if the argument \p ArgNum of \p Attr is a ASCII string literal.
/// If not emit an error and return false. If the argument is an identifier it
/// will emit an error with a fixit hint and treat it as if it was a string
/// literal.
bool Sema::checkStringLiteralArgumentAttr(const ParsedAttr &AL, unsigned ArgNum,
                                          StringRef &Str,
                                          SourceLocation *ArgLocation) {
  // Look for identifiers. If we have one emit a hint to fix it to a literal.
  if (AL.isArgIdent(ArgNum)) {
    IdentifierLoc *Loc = AL.getArgAsIdent(ArgNum);
    Diag(Loc->Loc, diag::err_attribute_argument_type)
        << AL << AANT_ArgumentString
        << FixItHint::CreateInsertion(Loc->Loc, "\"")
        << FixItHint::CreateInsertion(getLocForEndOfToken(Loc->Loc), "\"");
    Str = Loc->Ident->getName();
    if (ArgLocation)
      *ArgLocation = Loc->Loc;
    return true;
  }
 
  // Now check for an actual string literal.
  Expr *ArgExpr = AL.getArgAsExpr(ArgNum);
  return checkStringLiteralArgumentAttr(AL, ArgExpr, Str, ArgLocation);
}
 
/// Applies the given attribute to the Decl without performing any
/// additional semantic checking.
template <typename AttrType>
static void handleSimpleAttribute(Sema &S, Decl *D,
                                  const AttributeCommonInfo &CI) {
  D->addAttr(::new (S.Context) AttrType(S.Context, CI));
}
 
template <typename... DiagnosticArgs>
static const Sema::SemaDiagnosticBuilder&
appendDiagnostics(const Sema::SemaDiagnosticBuilder &Bldr) {
  return Bldr;
}
 
template <typename T, typename... DiagnosticArgs>
static const Sema::SemaDiagnosticBuilder&
appendDiagnostics(const Sema::SemaDiagnosticBuilder &Bldr, T &&ExtraArg,
                  DiagnosticArgs &&... ExtraArgs) {
  return appendDiagnostics(Bldr << std::forward<T>(ExtraArg),
                           std::forward<DiagnosticArgs>(ExtraArgs)...);
}
 
/// Add an attribute @c AttrType to declaration @c D, provided that
/// @c PassesCheck is true.
/// Otherwise, emit diagnostic @c DiagID, passing in all parameters
/// specified in @c ExtraArgs.
template <typename AttrType, typename... DiagnosticArgs>
static void handleSimpleAttributeOrDiagnose(Sema &S, Decl *D,
                                            const AttributeCommonInfo &CI,
                                            bool PassesCheck, unsigned DiagID,
                                            DiagnosticArgs &&... ExtraArgs) {
  if (!PassesCheck) {
    Sema::SemaDiagnosticBuilder DB = S.Diag(D->getBeginLoc(), DiagID);
    appendDiagnostics(DB, std::forward<DiagnosticArgs>(ExtraArgs)...);
    return;
  }
  handleSimpleAttribute<AttrType>(S, D, CI);
}
 
/// Check if the passed-in expression is of type int or bool.
static bool isIntOrBool(Expr *Exp) {
  QualType QT = Exp->getType();
  return QT->isBooleanType() || QT->isIntegerType();
}
 
 
// Check to see if the type is a smart pointer of some kind.  We assume
// it's a smart pointer if it defines both operator-> and operator*.
static bool threadSafetyCheckIsSmartPointer(Sema &S, const RecordType* RT) {
  auto IsOverloadedOperatorPresent = [&S](const RecordDecl *Record,
                                          OverloadedOperatorKind Op) {
    DeclContextLookupResult Result =
        Record->lookup(S.Context.DeclarationNames.getCXXOperatorName(Op));
    return !Result.empty();
  };
 
  const RecordDecl *Record = RT->getDecl();
  bool foundStarOperator = IsOverloadedOperatorPresent(Record, OO_Star);
  bool foundArrowOperator = IsOverloadedOperatorPresent(Record, OO_Arrow);
  if (foundStarOperator && foundArrowOperator)
    return true;
 
  const CXXRecordDecl *CXXRecord = dyn_cast<CXXRecordDecl>(Record);
  if (!CXXRecord)
    return false;
 
  for (auto BaseSpecifier : CXXRecord->bases()) {
    if (!foundStarOperator)
      foundStarOperator = IsOverloadedOperatorPresent(
          BaseSpecifier.getType()->getAsRecordDecl(), OO_Star);
    if (!foundArrowOperator)
      foundArrowOperator = IsOverloadedOperatorPresent(
          BaseSpecifier.getType()->getAsRecordDecl(), OO_Arrow);
  }
 
  if (foundStarOperator && foundArrowOperator)
    return true;
 
  return false;
}
 
/// Check if passed in Decl is a pointer type.
/// Note that this function may produce an error message.
/// \return true if the Decl is a pointer type; false otherwise
static bool threadSafetyCheckIsPointer(Sema &S, const Decl *D,
                                       const ParsedAttr &AL) {
  const auto *VD = cast<ValueDecl>(D);
  QualType QT = VD->getType();
  if (QT->isAnyPointerType())
    return true;
 
  if (const auto *RT = QT->getAs<RecordType>()) {
    // If it's an incomplete type, it could be a smart pointer; skip it.
    // (We don't want to force template instantiation if we can avoid it,
    // since that would alter the order in which templates are instantiated.)
    if (RT->isIncompleteType())
      return true;
 
    if (threadSafetyCheckIsSmartPointer(S, RT))
      return true;
  }
 
  S.Diag(AL.getLoc(), diag::warn_thread_attribute_decl_not_pointer) << AL << QT;
  return false;
}
 
/// Checks that the passed in QualType either is of RecordType or points
/// to RecordType. Returns the relevant RecordType, null if it does not exit.
static const RecordType *getRecordType(QualType QT) {
  if (const auto *RT = QT->getAs<RecordType>())
    return RT;
 
  // Now check if we point to record type.
  if (const auto *PT = QT->getAs<PointerType>())
    return PT->getPointeeType()->getAs<RecordType>();
 
  return nullptr;
}
 
template <typename AttrType>
static bool checkRecordDeclForAttr(const RecordDecl *RD) {
  // Check if the record itself has the attribute.
  if (RD->hasAttr<AttrType>())
    return true;
 
  // Else check if any base classes have the attribute.
  if (const auto *CRD = dyn_cast<CXXRecordDecl>(RD)) {
    if (!CRD->forallBases([](const CXXRecordDecl *Base) {
          return !Base->hasAttr<AttrType>();
        }))
      return true;
  }
  return false;
}
 
static bool checkRecordTypeForCapability(Sema &S, QualType Ty) {
  const RecordType *RT = getRecordType(Ty);
 
  if (!RT)
    return false;
 
  // Don't check for the capability if the class hasn't been defined yet.
  if (RT->isIncompleteType())
    return true;
 
  // Allow smart pointers to be used as capability objects.
  // FIXME -- Check the type that the smart pointer points to.
  if (threadSafetyCheckIsSmartPointer(S, RT))
    return true;
 
  return checkRecordDeclForAttr<CapabilityAttr>(RT->getDecl());
}
 
static bool checkTypedefTypeForCapability(QualType Ty) {
  const auto *TD = Ty->getAs<TypedefType>();
  if (!TD)
    return false;
 
  TypedefNameDecl *TN = TD->getDecl();
  if (!TN)
    return false;
 
  return TN->hasAttr<CapabilityAttr>();
}
 
static bool typeHasCapability(Sema &S, QualType Ty) {
  if (checkTypedefTypeForCapability(Ty))
    return true;
 
  if (checkRecordTypeForCapability(S, Ty))
    return true;
 
  return false;
}
 
static bool isCapabilityExpr(Sema &S, const Expr *Ex) {
  // Capability expressions are simple expressions involving the boolean logic
  // operators &&, || or !, a simple DeclRefExpr, CastExpr or a ParenExpr. Once
  // a DeclRefExpr is found, its type should be checked to determine whether it
  // is a capability or not.
 
  if (const auto *E = dyn_cast<CastExpr>(Ex))
    return isCapabilityExpr(S, E->getSubExpr());
  else if (const auto *E = dyn_cast<ParenExpr>(Ex))
    return isCapabilityExpr(S, E->getSubExpr());
  else if (const auto *E = dyn_cast<UnaryOperator>(Ex)) {
    if (E->getOpcode() == UO_LNot || E->getOpcode() == UO_AddrOf ||
        E->getOpcode() == UO_Deref)
      return isCapabilityExpr(S, E->getSubExpr());
    return false;
  } else if (const auto *E = dyn_cast<BinaryOperator>(Ex)) {
    if (E->getOpcode() == BO_LAnd || E->getOpcode() == BO_LOr)
      return isCapabilityExpr(S, E->getLHS()) &&
             isCapabilityExpr(S, E->getRHS());
    return false;
  }
 
  return typeHasCapability(S, Ex->getType());
}
 
/// Checks that all attribute arguments, starting from Sidx, resolve to
/// a capability object.
/// \param Sidx The attribute argument index to start checking with.
/// \param ParamIdxOk Whether an argument can be indexing into a function
/// parameter list.
static void checkAttrArgsAreCapabilityObjs(Sema &S, Decl *D,
                                           const ParsedAttr &AL,
                                           SmallVectorImpl<Expr *> &Args,
                                           unsigned Sidx = 0,
                                           bool ParamIdxOk = false) {
  if (Sidx == AL.getNumArgs()) {
    // If we don't have any capability arguments, the attribute implicitly
    // refers to 'this'. So we need to make sure that 'this' exists, i.e. we're
    // a non-static method, and that the class is a (scoped) capability.
    const auto *MD = dyn_cast<const CXXMethodDecl>(D);
    if (MD && !MD->isStatic()) {
      const CXXRecordDecl *RD = MD->getParent();
      // FIXME -- need to check this again on template instantiation
      if (!checkRecordDeclForAttr<CapabilityAttr>(RD) &&
          !checkRecordDeclForAttr<ScopedLockableAttr>(RD))
        S.Diag(AL.getLoc(),
               diag::warn_thread_attribute_not_on_capability_member)
            << AL << MD->getParent();
    } else {
      S.Diag(AL.getLoc(), diag::warn_thread_attribute_not_on_non_static_member)
          << AL;
    }
  }
 
  for (unsigned Idx = Sidx; Idx < AL.getNumArgs(); ++Idx) {
    Expr *ArgExp = AL.getArgAsExpr(Idx);
 
    if (ArgExp->isTypeDependent()) {
      // FIXME -- need to check this again on template instantiation
      Args.push_back(ArgExp);
      continue;
    }
 
    if (const auto *StrLit = dyn_cast<StringLiteral>(ArgExp)) {
      if (StrLit->getLength() == 0 ||
          (StrLit->isOrdinary() && StrLit->getString() == StringRef("*"))) {
        // Pass empty strings to the analyzer without warnings.
        // Treat "*" as the universal lock.
        Args.push_back(ArgExp);
        continue;
      }
 
      // We allow constant strings to be used as a placeholder for expressions
      // that are not valid C++ syntax, but warn that they are ignored.
      S.Diag(AL.getLoc(), diag::warn_thread_attribute_ignored) << AL;
      Args.push_back(ArgExp);
      continue;
    }
 
    QualType ArgTy = ArgExp->getType();
 
    // A pointer to member expression of the form  &MyClass::mu is treated
    // specially -- we need to look at the type of the member.
    if (const auto *UOp = dyn_cast<UnaryOperator>(ArgExp))
      if (UOp->getOpcode() == UO_AddrOf)
        if (const auto *DRE = dyn_cast<DeclRefExpr>(UOp->getSubExpr()))
          if (DRE->getDecl()->isCXXInstanceMember())
            ArgTy = DRE->getDecl()->getType();
 
    // First see if we can just cast to record type, or pointer to record type.
    const RecordType *RT = getRecordType(ArgTy);
 
    // Now check if we index into a record type function param.
    if(!RT && ParamIdxOk) {
      const auto *FD = dyn_cast<FunctionDecl>(D);
      const auto *IL = dyn_cast<IntegerLiteral>(ArgExp);
      if(FD && IL) {
        unsigned int NumParams = FD->getNumParams();
        llvm::APInt ArgValue = IL->getValue();
        uint64_t ParamIdxFromOne = ArgValue.getZExtValue();
        uint64_t ParamIdxFromZero = ParamIdxFromOne - 1;
        if (!ArgValue.isStrictlyPositive() || ParamIdxFromOne > NumParams) {
          S.Diag(AL.getLoc(),
                 diag::err_attribute_argument_out_of_bounds_extra_info)
              << AL << Idx + 1 << NumParams;
          continue;
        }
        ArgTy = FD->getParamDecl(ParamIdxFromZero)->getType();
      }
    }
 
    // If the type does not have a capability, see if the components of the
    // expression have capabilities. This allows for writing C code where the
    // capability may be on the type, and the expression is a capability
    // boolean logic expression. Eg) requires_capability(A || B && !C)
    if (!typeHasCapability(S, ArgTy) && !isCapabilityExpr(S, ArgExp))
      S.Diag(AL.getLoc(), diag::warn_thread_attribute_argument_not_lockable)
          << AL << ArgTy;
 
    Args.push_back(ArgExp);
  }
}
 
//===----------------------------------------------------------------------===//
// Attribute Implementations
//===----------------------------------------------------------------------===//
 
static void handlePtGuardedVarAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!threadSafetyCheckIsPointer(S, D, AL))
    return;
 
  D->addAttr(::new (S.Context) PtGuardedVarAttr(S.Context, AL));
}
 
static bool checkGuardedByAttrCommon(Sema &S, Decl *D, const ParsedAttr &AL,
                                     Expr *&Arg) {
  SmallVector<Expr *, 1> Args;
  // check that all arguments are lockable objects
  checkAttrArgsAreCapabilityObjs(S, D, AL, Args);
  unsigned Size = Args.size();
  if (Size != 1)
    return false;
 
  Arg = Args[0];
 
  return true;
}
 
static void handleGuardedByAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  Expr *Arg = nullptr;
  if (!checkGuardedByAttrCommon(S, D, AL, Arg))
    return;
 
  D->addAttr(::new (S.Context) GuardedByAttr(S.Context, AL, Arg));
}
 
static void handlePtGuardedByAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  Expr *Arg = nullptr;
  if (!checkGuardedByAttrCommon(S, D, AL, Arg))
    return;
 
  if (!threadSafetyCheckIsPointer(S, D, AL))
    return;
 
  D->addAttr(::new (S.Context) PtGuardedByAttr(S.Context, AL, Arg));
}
 
static bool checkAcquireOrderAttrCommon(Sema &S, Decl *D, const ParsedAttr &AL,
                                        SmallVectorImpl<Expr *> &Args) {
  if (!AL.checkAtLeastNumArgs(S, 1))
    return false;
 
  // Check that this attribute only applies to lockable types.
  QualType QT = cast<ValueDecl>(D)->getType();
  if (!QT->isDependentType() && !typeHasCapability(S, QT)) {
    S.Diag(AL.getLoc(), diag::warn_thread_attribute_decl_not_lockable) << AL;
    return false;
  }
 
  // Check that all arguments are lockable objects.
  checkAttrArgsAreCapabilityObjs(S, D, AL, Args);
  if (Args.empty())
    return false;
 
  return true;
}
 
static void handleAcquiredAfterAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  SmallVector<Expr *, 1> Args;
  if (!checkAcquireOrderAttrCommon(S, D, AL, Args))
    return;
 
  Expr **StartArg = &Args[0];
  D->addAttr(::new (S.Context)
                 AcquiredAfterAttr(S.Context, AL, StartArg, Args.size()));
}
 
static void handleAcquiredBeforeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  SmallVector<Expr *, 1> Args;
  if (!checkAcquireOrderAttrCommon(S, D, AL, Args))
    return;
 
  Expr **StartArg = &Args[0];
  D->addAttr(::new (S.Context)
                 AcquiredBeforeAttr(S.Context, AL, StartArg, Args.size()));
}
 
static bool checkLockFunAttrCommon(Sema &S, Decl *D, const ParsedAttr &AL,
                                   SmallVectorImpl<Expr *> &Args) {
  // zero or more arguments ok
  // check that all arguments are lockable objects
  checkAttrArgsAreCapabilityObjs(S, D, AL, Args, 0, /*ParamIdxOk=*/true);
 
  return true;
}
 
static void handleAssertSharedLockAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  SmallVector<Expr *, 1> Args;
  if (!checkLockFunAttrCommon(S, D, AL, Args))
    return;
 
  unsigned Size = Args.size();
  Expr **StartArg = Size == 0 ? nullptr : &Args[0];
  D->addAttr(::new (S.Context)
                 AssertSharedLockAttr(S.Context, AL, StartArg, Size));
}
 
static void handleAssertExclusiveLockAttr(Sema &S, Decl *D,
                                          const ParsedAttr &AL) {
  SmallVector<Expr *, 1> Args;
  if (!checkLockFunAttrCommon(S, D, AL, Args))
    return;
 
  unsigned Size = Args.size();
  Expr **StartArg = Size == 0 ? nullptr : &Args[0];
  D->addAttr(::new (S.Context)
                 AssertExclusiveLockAttr(S.Context, AL, StartArg, Size));
}
 
/// Checks to be sure that the given parameter number is in bounds, and
/// is an integral type. Will emit appropriate diagnostics if this returns
/// false.
///
/// AttrArgNo is used to actually retrieve the argument, so it's base-0.
template <typename AttrInfo>
static bool checkParamIsIntegerType(Sema &S, const Decl *D, const AttrInfo &AI,
                                    unsigned AttrArgNo) {
  assert(AI.isArgExpr(AttrArgNo) && "Expected expression argument");
  Expr *AttrArg = AI.getArgAsExpr(AttrArgNo);
  ParamIdx Idx;
  if (!checkFunctionOrMethodParameterIndex(S, D, AI, AttrArgNo + 1, AttrArg,
                                           Idx))
    return false;
 
  QualType ParamTy = getFunctionOrMethodParamType(D, Idx.getASTIndex());
  if (!ParamTy->isIntegerType() && !ParamTy->isCharType()) {
    SourceLocation SrcLoc = AttrArg->getBeginLoc();
    S.Diag(SrcLoc, diag::err_attribute_integers_only)
        << AI << getFunctionOrMethodParamRange(D, Idx.getASTIndex());
    return false;
  }
  return true;
}
 
static void handleAllocSizeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!AL.checkAtLeastNumArgs(S, 1) || !AL.checkAtMostNumArgs(S, 2))
    return;
 
  assert(isFunctionOrMethod(D) && hasFunctionProto(D));
 
  QualType RetTy = getFunctionOrMethodResultType(D);
  if (!RetTy->isPointerType()) {
    S.Diag(AL.getLoc(), diag::warn_attribute_return_pointers_only) << AL;
    return;
  }
 
  const Expr *SizeExpr = AL.getArgAsExpr(0);
  int SizeArgNoVal;
  // Parameter indices are 1-indexed, hence Index=1
  if (!checkPositiveIntArgument(S, AL, SizeExpr, SizeArgNoVal, /*Idx=*/1))
    return;
  if (!checkParamIsIntegerType(S, D, AL, /*AttrArgNo=*/0))
    return;
  ParamIdx SizeArgNo(SizeArgNoVal, D);
 
  ParamIdx NumberArgNo;
  if (AL.getNumArgs() == 2) {
    const Expr *NumberExpr = AL.getArgAsExpr(1);
    int Val;
    // Parameter indices are 1-based, hence Index=2
    if (!checkPositiveIntArgument(S, AL, NumberExpr, Val, /*Idx=*/2))
      return;
    if (!checkParamIsIntegerType(S, D, AL, /*AttrArgNo=*/1))
      return;
    NumberArgNo = ParamIdx(Val, D);
  }
 
  D->addAttr(::new (S.Context)
                 AllocSizeAttr(S.Context, AL, SizeArgNo, NumberArgNo));
}
 
static bool checkTryLockFunAttrCommon(Sema &S, Decl *D, const ParsedAttr &AL,
                                      SmallVectorImpl<Expr *> &Args) {
  if (!AL.checkAtLeastNumArgs(S, 1))
    return false;
 
  if (!isIntOrBool(AL.getArgAsExpr(0))) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
        << AL << 1 << AANT_ArgumentIntOrBool;
    return false;
  }
 
  // check that all arguments are lockable objects
  checkAttrArgsAreCapabilityObjs(S, D, AL, Args, 1);
 
  return true;
}
 
static void handleSharedTrylockFunctionAttr(Sema &S, Decl *D,
                                            const ParsedAttr &AL) {
  SmallVector<Expr*, 2> Args;
  if (!checkTryLockFunAttrCommon(S, D, AL, Args))
    return;
 
  D->addAttr(::new (S.Context) SharedTrylockFunctionAttr(
      S.Context, AL, AL.getArgAsExpr(0), Args.data(), Args.size()));
}
 
static void handleExclusiveTrylockFunctionAttr(Sema &S, Decl *D,
                                               const ParsedAttr &AL) {
  SmallVector<Expr*, 2> Args;
  if (!checkTryLockFunAttrCommon(S, D, AL, Args))
    return;
 
  D->addAttr(::new (S.Context) ExclusiveTrylockFunctionAttr(
      S.Context, AL, AL.getArgAsExpr(0), Args.data(), Args.size()));
}
 
static void handleLockReturnedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // check that the argument is lockable object
  SmallVector<Expr*, 1> Args;
  checkAttrArgsAreCapabilityObjs(S, D, AL, Args);
  unsigned Size = Args.size();
  if (Size == 0)
    return;
 
  D->addAttr(::new (S.Context) LockReturnedAttr(S.Context, AL, Args[0]));
}
 
static void handleLocksExcludedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!AL.checkAtLeastNumArgs(S, 1))
    return;
 
  // check that all arguments are lockable objects
  SmallVector<Expr*, 1> Args;
  checkAttrArgsAreCapabilityObjs(S, D, AL, Args);
  unsigned Size = Args.size();
  if (Size == 0)
    return;
  Expr **StartArg = &Args[0];
 
  D->addAttr(::new (S.Context)
                 LocksExcludedAttr(S.Context, AL, StartArg, Size));
}
 
static bool checkFunctionConditionAttr(Sema &S, Decl *D, const ParsedAttr &AL,
                                       Expr *&Cond, StringRef &Msg) {
  Cond = AL.getArgAsExpr(0);
  if (!Cond->isTypeDependent()) {
    ExprResult Converted = S.PerformContextuallyConvertToBool(Cond);
    if (Converted.isInvalid())
      return false;
    Cond = Converted.get();
  }
 
  if (!S.checkStringLiteralArgumentAttr(AL, 1, Msg))
    return false;
 
  if (Msg.empty())
    Msg = "<no message provided>";
 
  SmallVector<PartialDiagnosticAt, 8> Diags;
  if (isa<FunctionDecl>(D) && !Cond->isValueDependent() &&
      !Expr::isPotentialConstantExprUnevaluated(Cond, cast<FunctionDecl>(D),
                                                Diags)) {
    S.Diag(AL.getLoc(), diag::err_attr_cond_never_constant_expr) << AL;
    for (const PartialDiagnosticAt &PDiag : Diags)
      S.Diag(PDiag.first, PDiag.second);
    return false;
  }
  return true;
}
 
static void handleEnableIfAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  S.Diag(AL.getLoc(), diag::ext_clang_enable_if);
 
  Expr *Cond;
  StringRef Msg;
  if (checkFunctionConditionAttr(S, D, AL, Cond, Msg))
    D->addAttr(::new (S.Context) EnableIfAttr(S.Context, AL, Cond, Msg));
}
 
static void handleErrorAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  StringRef NewUserDiagnostic;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, NewUserDiagnostic))
    return;
  if (ErrorAttr *EA = S.mergeErrorAttr(D, AL, NewUserDiagnostic))
    D->addAttr(EA);
}
 
namespace {
/// Determines if a given Expr references any of the given function's
/// ParmVarDecls, or the function's implicit `this` parameter (if applicable).
class ArgumentDependenceChecker
    : public RecursiveASTVisitor<ArgumentDependenceChecker> {
#ifndef NDEBUG
  const CXXRecordDecl *ClassType;
#endif
  llvm::SmallPtrSet<const ParmVarDecl *, 16> Parms;
  bool Result;
 
public:
  ArgumentDependenceChecker(const FunctionDecl *FD) {
#ifndef NDEBUG
    if (const auto *MD = dyn_cast<CXXMethodDecl>(FD))
      ClassType = MD->getParent();
    else
      ClassType = nullptr;
#endif
    Parms.insert(FD->param_begin(), FD->param_end());
  }
 
  bool referencesArgs(Expr *E) {
    Result = false;
    TraverseStmt(E);
    return Result;
  }
 
  bool VisitCXXThisExpr(CXXThisExpr *E) {
    assert(E->getType()->getPointeeCXXRecordDecl() == ClassType &&
           "`this` doesn't refer to the enclosing class?");
    Result = true;
    return false;
  }
 
  bool VisitDeclRefExpr(DeclRefExpr *DRE) {
    if (const auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl()))
      if (Parms.count(PVD)) {
        Result = true;
        return false;
      }
    return true;
  }
};
}
 
static void handleDiagnoseAsBuiltinAttr(Sema &S, Decl *D,
                                        const ParsedAttr &AL) {
  const auto *DeclFD = cast<FunctionDecl>(D);
 
  if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(DeclFD))
    if (!MethodDecl->isStatic()) {
      S.Diag(AL.getLoc(), diag::err_attribute_no_member_function) << AL;
      return;
    }
 
  auto DiagnoseType = [&](unsigned Index, AttributeArgumentNType T) {
    SourceLocation Loc = [&]() {
      auto Union = AL.getArg(Index - 1);
      if (Union.is<Expr *>())
        return Union.get<Expr *>()->getBeginLoc();
      return Union.get<IdentifierLoc *>()->Loc;
    }();
 
    S.Diag(Loc, diag::err_attribute_argument_n_type) << AL << Index << T;
  };
 
  FunctionDecl *AttrFD = [&]() -> FunctionDecl * {
    if (!AL.isArgExpr(0))
      return nullptr;
    auto *F = dyn_cast_or_null<DeclRefExpr>(AL.getArgAsExpr(0));
    if (!F)
      return nullptr;
    return dyn_cast_or_null<FunctionDecl>(F->getFoundDecl());
  }();
 
  if (!AttrFD || !AttrFD->getBuiltinID(true)) {
    DiagnoseType(1, AANT_ArgumentBuiltinFunction);
    return;
  }
 
  if (AttrFD->getNumParams() != AL.getNumArgs() - 1) {
    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments_for)
        << AL << AttrFD << AttrFD->getNumParams();
    return;
  }
 
  SmallVector<unsigned, 8> Indices;
 
  for (unsigned I = 1; I < AL.getNumArgs(); ++I) {
    if (!AL.isArgExpr(I)) {
      DiagnoseType(I + 1, AANT_ArgumentIntegerConstant);
      return;
    }
 
    const Expr *IndexExpr = AL.getArgAsExpr(I);
    uint32_t Index;
 
    if (!checkUInt32Argument(S, AL, IndexExpr, Index, I + 1, false))
      return;
 
    if (Index > DeclFD->getNumParams()) {
      S.Diag(AL.getLoc(), diag::err_attribute_bounds_for_function)
          << AL << Index << DeclFD << DeclFD->getNumParams();
      return;
    }
 
    QualType T1 = AttrFD->getParamDecl(I - 1)->getType();
    QualType T2 = DeclFD->getParamDecl(Index - 1)->getType();
 
    if (T1.getCanonicalType().getUnqualifiedType() !=
        T2.getCanonicalType().getUnqualifiedType()) {
      S.Diag(IndexExpr->getBeginLoc(), diag::err_attribute_parameter_types)
          << AL << Index << DeclFD << T2 << I << AttrFD << T1;
      return;
    }
 
    Indices.push_back(Index - 1);
  }
 
  D->addAttr(::new (S.Context) DiagnoseAsBuiltinAttr(
      S.Context, AL, AttrFD, Indices.data(), Indices.size()));
}
 
static void handleDiagnoseIfAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  S.Diag(AL.getLoc(), diag::ext_clang_diagnose_if);
 
  Expr *Cond;
  StringRef Msg;
  if (!checkFunctionConditionAttr(S, D, AL, Cond, Msg))
    return;
 
  StringRef DiagTypeStr;
  if (!S.checkStringLiteralArgumentAttr(AL, 2, DiagTypeStr))
    return;
 
  DiagnoseIfAttr::DiagnosticType DiagType;
  if (!DiagnoseIfAttr::ConvertStrToDiagnosticType(DiagTypeStr, DiagType)) {
    S.Diag(AL.getArgAsExpr(2)->getBeginLoc(),
           diag::err_diagnose_if_invalid_diagnostic_type);
    return;
  }
 
  bool ArgDependent = false;
  if (const auto *FD = dyn_cast<FunctionDecl>(D))
    ArgDependent = ArgumentDependenceChecker(FD).referencesArgs(Cond);
  D->addAttr(::new (S.Context) DiagnoseIfAttr(
      S.Context, AL, Cond, Msg, DiagType, ArgDependent, cast<NamedDecl>(D)));
}
 
static void handleNoBuiltinAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  static constexpr const StringRef kWildcard = "*";
 
  llvm::SmallVector<StringRef, 16> Names;
  bool HasWildcard = false;
 
  const auto AddBuiltinName = [&Names, &HasWildcard](StringRef Name) {
    if (Name == kWildcard)
      HasWildcard = true;
    Names.push_back(Name);
  };
 
  // Add previously defined attributes.
  if (const auto *NBA = D->getAttr<NoBuiltinAttr>())
    for (StringRef BuiltinName : NBA->builtinNames())
      AddBuiltinName(BuiltinName);
 
  // Add current attributes.
  if (AL.getNumArgs() == 0)
    AddBuiltinName(kWildcard);
  else
    for (unsigned I = 0, E = AL.getNumArgs(); I != E; ++I) {
      StringRef BuiltinName;
      SourceLocation LiteralLoc;
      if (!S.checkStringLiteralArgumentAttr(AL, I, BuiltinName, &LiteralLoc))
        return;
 
      if (Builtin::Context::isBuiltinFunc(BuiltinName))
        AddBuiltinName(BuiltinName);
      else
        S.Diag(LiteralLoc, diag::warn_attribute_no_builtin_invalid_builtin_name)
            << BuiltinName << AL;
    }
 
  // Repeating the same attribute is fine.
  llvm::sort(Names);
  Names.erase(std::unique(Names.begin(), Names.end()), Names.end());
 
  // Empty no_builtin must be on its own.
  if (HasWildcard && Names.size() > 1)
    S.Diag(D->getLocation(),
           diag::err_attribute_no_builtin_wildcard_or_builtin_name)
        << AL;
 
  if (D->hasAttr<NoBuiltinAttr>())
    D->dropAttr<NoBuiltinAttr>();
  D->addAttr(::new (S.Context)
                 NoBuiltinAttr(S.Context, AL, Names.data(), Names.size()));
}
 
static void handlePassObjectSizeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (D->hasAttr<PassObjectSizeAttr>()) {
    S.Diag(D->getBeginLoc(), diag::err_attribute_only_once_per_parameter) << AL;
    return;
  }
 
  Expr *E = AL.getArgAsExpr(0);
  uint32_t Type;
  if (!checkUInt32Argument(S, AL, E, Type, /*Idx=*/1))
    return;
 
  // pass_object_size's argument is passed in as the second argument of
  // __builtin_object_size. So, it has the same constraints as that second
  // argument; namely, it must be in the range [0, 3].
  if (Type > 3) {
    S.Diag(E->getBeginLoc(), diag::err_attribute_argument_out_of_range)
        << AL << 0 << 3 << E->getSourceRange();
    return;
  }
 
  // pass_object_size is only supported on constant pointer parameters; as a
  // kindness to users, we allow the parameter to be non-const for declarations.
  // At this point, we have no clue if `D` belongs to a function declaration or
  // definition, so we defer the constness check until later.
  if (!cast<ParmVarDecl>(D)->getType()->isPointerType()) {
    S.Diag(D->getBeginLoc(), diag::err_attribute_pointers_only) << AL << 1;
    return;
  }
 
  D->addAttr(::new (S.Context) PassObjectSizeAttr(S.Context, AL, (int)Type));
}
 
static void handleConsumableAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  ConsumableAttr::ConsumedState DefaultState;
 
  if (AL.isArgIdent(0)) {
    IdentifierLoc *IL = AL.getArgAsIdent(0);
    if (!ConsumableAttr::ConvertStrToConsumedState(IL->Ident->getName(),
                                                   DefaultState)) {
      S.Diag(IL->Loc, diag::warn_attribute_type_not_supported) << AL
                                                               << IL->Ident;
      return;
    }
  } else {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_type)
        << AL << AANT_ArgumentIdentifier;
    return;
  }
 
  D->addAttr(::new (S.Context) ConsumableAttr(S.Context, AL, DefaultState));
}
 
static bool checkForConsumableClass(Sema &S, const CXXMethodDecl *MD,
                                    const ParsedAttr &AL) {
  QualType ThisType = MD->getThisType()->getPointeeType();
 
  if (const CXXRecordDecl *RD = ThisType->getAsCXXRecordDecl()) {
    if (!RD->hasAttr<ConsumableAttr>()) {
      S.Diag(AL.getLoc(), diag::warn_attr_on_unconsumable_class) << RD;
 
      return false;
    }
  }
 
  return true;
}
 
static void handleCallableWhenAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!AL.checkAtLeastNumArgs(S, 1))
    return;
 
  if (!checkForConsumableClass(S, cast<CXXMethodDecl>(D), AL))
    return;
 
  SmallVector<CallableWhenAttr::ConsumedState, 3> States;
  for (unsigned ArgIndex = 0; ArgIndex < AL.getNumArgs(); ++ArgIndex) {
    CallableWhenAttr::ConsumedState CallableState;
 
    StringRef StateString;
    SourceLocation Loc;
    if (AL.isArgIdent(ArgIndex)) {
      IdentifierLoc *Ident = AL.getArgAsIdent(ArgIndex);
      StateString = Ident->Ident->getName();
      Loc = Ident->Loc;
    } else {
      if (!S.checkStringLiteralArgumentAttr(AL, ArgIndex, StateString, &Loc))
        return;
    }
 
    if (!CallableWhenAttr::ConvertStrToConsumedState(StateString,
                                                     CallableState)) {
      S.Diag(Loc, diag::warn_attribute_type_not_supported) << AL << StateString;
      return;
    }
 
    States.push_back(CallableState);
  }
 
  D->addAttr(::new (S.Context)
                 CallableWhenAttr(S.Context, AL, States.data(), States.size()));
}
 
static void handleParamTypestateAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  ParamTypestateAttr::ConsumedState ParamState;
 
  if (AL.isArgIdent(0)) {
    IdentifierLoc *Ident = AL.getArgAsIdent(0);
    StringRef StateString = Ident->Ident->getName();
 
    if (!ParamTypestateAttr::ConvertStrToConsumedState(StateString,
                                                       ParamState)) {
      S.Diag(Ident->Loc, diag::warn_attribute_type_not_supported)
          << AL << StateString;
      return;
    }
  } else {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_type)
        << AL << AANT_ArgumentIdentifier;
    return;
  }
 
  // FIXME: This check is currently being done in the analysis.  It can be
  //        enabled here only after the parser propagates attributes at
  //        template specialization definition, not declaration.
  //QualType ReturnType = cast<ParmVarDecl>(D)->getType();
  //const CXXRecordDecl *RD = ReturnType->getAsCXXRecordDecl();
  //
  //if (!RD || !RD->hasAttr<ConsumableAttr>()) {
  //    S.Diag(AL.getLoc(), diag::warn_return_state_for_unconsumable_type) <<
  //      ReturnType.getAsString();
  //    return;
  //}
 
  D->addAttr(::new (S.Context) ParamTypestateAttr(S.Context, AL, ParamState));
}
 
static void handleReturnTypestateAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  ReturnTypestateAttr::ConsumedState ReturnState;
 
  if (AL.isArgIdent(0)) {
    IdentifierLoc *IL = AL.getArgAsIdent(0);
    if (!ReturnTypestateAttr::ConvertStrToConsumedState(IL->Ident->getName(),
                                                        ReturnState)) {
      S.Diag(IL->Loc, diag::warn_attribute_type_not_supported) << AL
                                                               << IL->Ident;
      return;
    }
  } else {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_type)
        << AL << AANT_ArgumentIdentifier;
    return;
  }
 
  // FIXME: This check is currently being done in the analysis.  It can be
  //        enabled here only after the parser propagates attributes at
  //        template specialization definition, not declaration.
  //QualType ReturnType;
  //
  //if (const ParmVarDecl *Param = dyn_cast<ParmVarDecl>(D)) {
  //  ReturnType = Param->getType();
  //
  //} else if (const CXXConstructorDecl *Constructor =
  //             dyn_cast<CXXConstructorDecl>(D)) {
  //  ReturnType = Constructor->getThisType()->getPointeeType();
  //
  //} else {
  //
  //  ReturnType = cast<FunctionDecl>(D)->getCallResultType();
  //}
  //
  //const CXXRecordDecl *RD = ReturnType->getAsCXXRecordDecl();
  //
  //if (!RD || !RD->hasAttr<ConsumableAttr>()) {
  //    S.Diag(Attr.getLoc(), diag::warn_return_state_for_unconsumable_type) <<
  //      ReturnType.getAsString();
  //    return;
  //}
 
  D->addAttr(::new (S.Context) ReturnTypestateAttr(S.Context, AL, ReturnState));
}
 
static void handleSetTypestateAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!checkForConsumableClass(S, cast<CXXMethodDecl>(D), AL))
    return;
 
  SetTypestateAttr::ConsumedState NewState;
  if (AL.isArgIdent(0)) {
    IdentifierLoc *Ident = AL.getArgAsIdent(0);
    StringRef Param = Ident->Ident->getName();
    if (!SetTypestateAttr::ConvertStrToConsumedState(Param, NewState)) {
      S.Diag(Ident->Loc, diag::warn_attribute_type_not_supported) << AL
                                                                  << Param;
      return;
    }
  } else {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_type)
        << AL << AANT_ArgumentIdentifier;
    return;
  }
 
  D->addAttr(::new (S.Context) SetTypestateAttr(S.Context, AL, NewState));
}
 
static void handleTestTypestateAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!checkForConsumableClass(S, cast<CXXMethodDecl>(D), AL))
    return;
 
  TestTypestateAttr::ConsumedState TestState;
  if (AL.isArgIdent(0)) {
    IdentifierLoc *Ident = AL.getArgAsIdent(0);
    StringRef Param = Ident->Ident->getName();
    if (!TestTypestateAttr::ConvertStrToConsumedState(Param, TestState)) {
      S.Diag(Ident->Loc, diag::warn_attribute_type_not_supported) << AL
                                                                  << Param;
      return;
    }
  } else {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_type)
        << AL << AANT_ArgumentIdentifier;
    return;
  }
 
  D->addAttr(::new (S.Context) TestTypestateAttr(S.Context, AL, TestState));
}
 
static void handleExtVectorTypeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Remember this typedef decl, we will need it later for diagnostics.
  S.ExtVectorDecls.push_back(cast<TypedefNameDecl>(D));
}
 
static void handlePackedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (auto *TD = dyn_cast<TagDecl>(D))
    TD->addAttr(::new (S.Context) PackedAttr(S.Context, AL));
  else if (auto *FD = dyn_cast<FieldDecl>(D)) {
    bool BitfieldByteAligned = (!FD->getType()->isDependentType() &&
                                !FD->getType()->isIncompleteType() &&
                                FD->isBitField() &&
                                S.Context.getTypeAlign(FD->getType()) <= 8);
 
    if (S.getASTContext().getTargetInfo().getTriple().isPS()) {
      if (BitfieldByteAligned)
        // The PS4/PS5 targets need to maintain ABI backwards compatibility.
        S.Diag(AL.getLoc(), diag::warn_attribute_ignored_for_field_of_type)
            << AL << FD->getType();
      else
        FD->addAttr(::new (S.Context) PackedAttr(S.Context, AL));
    } else {
      // Report warning about changed offset in the newer compiler versions.
      if (BitfieldByteAligned)
        S.Diag(AL.getLoc(), diag::warn_attribute_packed_for_bitfield);
 
      FD->addAttr(::new (S.Context) PackedAttr(S.Context, AL));
    }
 
  } else
    S.Diag(AL.getLoc(), diag::warn_attribute_ignored) << AL;
}
 
static void handlePreferredName(Sema &S, Decl *D, const ParsedAttr &AL) {
  auto *RD = cast<CXXRecordDecl>(D);
  ClassTemplateDecl *CTD = RD->getDescribedClassTemplate();
  assert(CTD && "attribute does not appertain to this declaration");
 
  ParsedType PT = AL.getTypeArg();
  TypeSourceInfo *TSI = nullptr;
  QualType T = S.GetTypeFromParser(PT, &TSI);
  if (!TSI)
    TSI = S.Context.getTrivialTypeSourceInfo(T, AL.getLoc());
 
  if (!T.hasQualifiers() && T->isTypedefNameType()) {
    // Find the template name, if this type names a template specialization.
    const TemplateDecl *Template = nullptr;
    if (const auto *CTSD = dyn_cast_or_null<ClassTemplateSpecializationDecl>(
            T->getAsCXXRecordDecl())) {
      Template = CTSD->getSpecializedTemplate();
    } else if (const auto *TST = T->getAs<TemplateSpecializationType>()) {
      while (TST && TST->isTypeAlias())
        TST = TST->getAliasedType()->getAs<TemplateSpecializationType>();
      if (TST)
        Template = TST->getTemplateName().getAsTemplateDecl();
    }
 
    if (Template && declaresSameEntity(Template, CTD)) {
      D->addAttr(::new (S.Context) PreferredNameAttr(S.Context, AL, TSI));
      return;
    }
  }
 
  S.Diag(AL.getLoc(), diag::err_attribute_preferred_name_arg_invalid)
      << T << CTD;
  if (const auto *TT = T->getAs<TypedefType>())
    S.Diag(TT->getDecl()->getLocation(), diag::note_entity_declared_at)
        << TT->getDecl();
}
 
static bool checkIBOutletCommon(Sema &S, Decl *D, const ParsedAttr &AL) {
  // The IBOutlet/IBOutletCollection attributes only apply to instance
  // variables or properties of Objective-C classes.  The outlet must also
  // have an object reference type.
  if (const auto *VD = dyn_cast<ObjCIvarDecl>(D)) {
    if (!VD->getType()->getAs<ObjCObjectPointerType>()) {
      S.Diag(AL.getLoc(), diag::warn_iboutlet_object_type)
          << AL << VD->getType() << 0;
      return false;
    }
  }
  else if (const auto *PD = dyn_cast<ObjCPropertyDecl>(D)) {
    if (!PD->getType()->getAs<ObjCObjectPointerType>()) {
      S.Diag(AL.getLoc(), diag::warn_iboutlet_object_type)
          << AL << PD->getType() << 1;
      return false;
    }
  }
  else {
    S.Diag(AL.getLoc(), diag::warn_attribute_iboutlet) << AL;
    return false;
  }
 
  return true;
}
 
static void handleIBOutlet(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!checkIBOutletCommon(S, D, AL))
    return;
 
  D->addAttr(::new (S.Context) IBOutletAttr(S.Context, AL));
}
 
static void handleIBOutletCollection(Sema &S, Decl *D, const ParsedAttr &AL) {
 
  // The iboutletcollection attribute can have zero or one arguments.
  if (AL.getNumArgs() > 1) {
    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 1;
    return;
  }
 
  if (!checkIBOutletCommon(S, D, AL))
    return;
 
  ParsedType PT;
 
  if (AL.hasParsedType())
    PT = AL.getTypeArg();
  else {
    PT = S.getTypeName(S.Context.Idents.get("NSObject"), AL.getLoc(),
                       S.getScopeForContext(D->getDeclContext()->getParent()));
    if (!PT) {
      S.Diag(AL.getLoc(), diag::err_iboutletcollection_type) << "NSObject";
      return;
    }
  }
 
  TypeSourceInfo *QTLoc = nullptr;
  QualType QT = S.GetTypeFromParser(PT, &QTLoc);
  if (!QTLoc)
    QTLoc = S.Context.getTrivialTypeSourceInfo(QT, AL.getLoc());
 
  // Diagnose use of non-object type in iboutletcollection attribute.
  // FIXME. Gnu attribute extension ignores use of builtin types in
  // attributes. So, __attribute__((iboutletcollection(char))) will be
  // treated as __attribute__((iboutletcollection())).
  if (!QT->isObjCIdType() && !QT->isObjCObjectType()) {
    S.Diag(AL.getLoc(),
           QT->isBuiltinType() ? diag::err_iboutletcollection_builtintype
                               : diag::err_iboutletcollection_type) << QT;
    return;
  }
 
  D->addAttr(::new (S.Context) IBOutletCollectionAttr(S.Context, AL, QTLoc));
}
 
bool Sema::isValidPointerAttrType(QualType T, bool RefOkay) {
  if (RefOkay) {
    if (T->isReferenceType())
      return true;
  } else {
    T = T.getNonReferenceType();
  }
 
  // The nonnull attribute, and other similar attributes, can be applied to a
  // transparent union that contains a pointer type.
  if (const RecordType *UT = T->getAsUnionType()) {
    if (UT && UT->getDecl()->hasAttr<TransparentUnionAttr>()) {
      RecordDecl *UD = UT->getDecl();
      for (const auto *I : UD->fields()) {
        QualType QT = I->getType();
        if (QT->isAnyPointerType() || QT->isBlockPointerType())
          return true;
      }
    }
  }
 
  return T->isAnyPointerType() || T->isBlockPointerType();
}
 
static bool attrNonNullArgCheck(Sema &S, QualType T, const ParsedAttr &AL,
                                SourceRange AttrParmRange,
                                SourceRange TypeRange,
                                bool isReturnValue = false) {
  if (!S.isValidPointerAttrType(T)) {
    if (isReturnValue)
      S.Diag(AL.getLoc(), diag::warn_attribute_return_pointers_only)
          << AL << AttrParmRange << TypeRange;
    else
      S.Diag(AL.getLoc(), diag::warn_attribute_pointers_only)
          << AL << AttrParmRange << TypeRange << 0;
    return false;
  }
  return true;
}
 
static void handleNonNullAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  SmallVector<ParamIdx, 8> NonNullArgs;
  for (unsigned I = 0; I < AL.getNumArgs(); ++I) {
    Expr *Ex = AL.getArgAsExpr(I);
    ParamIdx Idx;
    if (!checkFunctionOrMethodParameterIndex(S, D, AL, I + 1, Ex, Idx))
      return;
 
    // Is the function argument a pointer type?
    if (Idx.getASTIndex() < getFunctionOrMethodNumParams(D) &&
        !attrNonNullArgCheck(
            S, getFunctionOrMethodParamType(D, Idx.getASTIndex()), AL,
            Ex->getSourceRange(),
            getFunctionOrMethodParamRange(D, Idx.getASTIndex())))
      continue;
 
    NonNullArgs.push_back(Idx);
  }
 
  // If no arguments were specified to __attribute__((nonnull)) then all pointer
  // arguments have a nonnull attribute; warn if there aren't any. Skip this
  // check if the attribute came from a macro expansion or a template
  // instantiation.
  if (NonNullArgs.empty() && AL.getLoc().isFileID() &&
      !S.inTemplateInstantiation()) {
    bool AnyPointers = isFunctionOrMethodVariadic(D);
    for (unsigned I = 0, E = getFunctionOrMethodNumParams(D);
         I != E && !AnyPointers; ++I) {
      QualType T = getFunctionOrMethodParamType(D, I);
      if (T->isDependentType() || S.isValidPointerAttrType(T))
        AnyPointers = true;
    }
 
    if (!AnyPointers)
      S.Diag(AL.getLoc(), diag::warn_attribute_nonnull_no_pointers);
  }
 
  ParamIdx *Start = NonNullArgs.data();
  unsigned Size = NonNullArgs.size();
  llvm::array_pod_sort(Start, Start + Size);
  D->addAttr(::new (S.Context) NonNullAttr(S.Context, AL, Start, Size));
}
 
static void handleNonNullAttrParameter(Sema &S, ParmVarDecl *D,
                                       const ParsedAttr &AL) {
  if (AL.getNumArgs() > 0) {
    if (D->getFunctionType()) {
      handleNonNullAttr(S, D, AL);
    } else {
      S.Diag(AL.getLoc(), diag::warn_attribute_nonnull_parm_no_args)
        << D->getSourceRange();
    }
    return;
  }
 
  // Is the argument a pointer type?
  if (!attrNonNullArgCheck(S, D->getType(), AL, SourceRange(),
                           D->getSourceRange()))
    return;
 
  D->addAttr(::new (S.Context) NonNullAttr(S.Context, AL, nullptr, 0));
}
 
static void handleReturnsNonNullAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  QualType ResultType = getFunctionOrMethodResultType(D);
  SourceRange SR = getFunctionOrMethodResultSourceRange(D);
  if (!attrNonNullArgCheck(S, ResultType, AL, SourceRange(), SR,
                           /* isReturnValue */ true))
    return;
 
  D->addAttr(::new (S.Context) ReturnsNonNullAttr(S.Context, AL));
}
 
static void handleNoEscapeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (D->isInvalidDecl())
    return;
 
  // noescape only applies to pointer types.
  QualType T = cast<ParmVarDecl>(D)->getType();
  if (!S.isValidPointerAttrType(T, /* RefOkay */ true)) {
    S.Diag(AL.getLoc(), diag::warn_attribute_pointers_only)
        << AL << AL.getRange() << 0;
    return;
  }
 
  D->addAttr(::new (S.Context) NoEscapeAttr(S.Context, AL));
}
 
static void handleAssumeAlignedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  Expr *E = AL.getArgAsExpr(0),
       *OE = AL.getNumArgs() > 1 ? AL.getArgAsExpr(1) : nullptr;
  S.AddAssumeAlignedAttr(D, AL, E, OE);
}
 
static void handleAllocAlignAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  S.AddAllocAlignAttr(D, AL, AL.getArgAsExpr(0));
}
 
void Sema::AddAssumeAlignedAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E,
                                Expr *OE) {
  QualType ResultType = getFunctionOrMethodResultType(D);
  SourceRange SR = getFunctionOrMethodResultSourceRange(D);
 
  AssumeAlignedAttr TmpAttr(Context, CI, E, OE);
  SourceLocation AttrLoc = TmpAttr.getLocation();
 
  if (!isValidPointerAttrType(ResultType, /* RefOkay */ true)) {
    Diag(AttrLoc, diag::warn_attribute_return_pointers_refs_only)
        << &TmpAttr << TmpAttr.getRange() << SR;
    return;
  }
 
  if (!E->isValueDependent()) {
    std::optional<llvm::APSInt> I = llvm::APSInt(64);
    if (!(I = E->getIntegerConstantExpr(Context))) {
      if (OE)
        Diag(AttrLoc, diag::err_attribute_argument_n_type)
          << &TmpAttr << 1 << AANT_ArgumentIntegerConstant
          << E->getSourceRange();
      else
        Diag(AttrLoc, diag::err_attribute_argument_type)
          << &TmpAttr << AANT_ArgumentIntegerConstant
          << E->getSourceRange();
      return;
    }
 
    if (!I->isPowerOf2()) {
      Diag(AttrLoc, diag::err_alignment_not_power_of_two)
        << E->getSourceRange();
      return;
    }
 
    if (*I > Sema::MaximumAlignment)
      Diag(CI.getLoc(), diag::warn_assume_aligned_too_great)
          << CI.getRange() << Sema::MaximumAlignment;
  }
 
  if (OE && !OE->isValueDependent() && !OE->isIntegerConstantExpr(Context)) {
    Diag(AttrLoc, diag::err_attribute_argument_n_type)
        << &TmpAttr << 2 << AANT_ArgumentIntegerConstant
        << OE->getSourceRange();
    return;
  }
 
  D->addAttr(::new (Context) AssumeAlignedAttr(Context, CI, E, OE));
}
 
void Sema::AddAllocAlignAttr(Decl *D, const AttributeCommonInfo &CI,
                             Expr *ParamExpr) {
  QualType ResultType = getFunctionOrMethodResultType(D);
 
  AllocAlignAttr TmpAttr(Context, CI, ParamIdx());
  SourceLocation AttrLoc = CI.getLoc();
 
  if (!ResultType->isDependentType() &&
      !isValidPointerAttrType(ResultType, /* RefOkay */ true)) {
    Diag(AttrLoc, diag::warn_attribute_return_pointers_refs_only)
        << &TmpAttr << CI.getRange() << getFunctionOrMethodResultSourceRange(D);
    return;
  }
 
  ParamIdx Idx;
  const auto *FuncDecl = cast<FunctionDecl>(D);
  if (!checkFunctionOrMethodParameterIndex(*this, FuncDecl, TmpAttr,
                                           /*AttrArgNum=*/1, ParamExpr, Idx))
    return;
 
  QualType Ty = getFunctionOrMethodParamType(D, Idx.getASTIndex());
  if (!Ty->isDependentType() && !Ty->isIntegralType(Context) &&
      !Ty->isAlignValT()) {
    Diag(ParamExpr->getBeginLoc(), diag::err_attribute_integers_only)
        << &TmpAttr
        << FuncDecl->getParamDecl(Idx.getASTIndex())->getSourceRange();
    return;
  }
 
  D->addAttr(::new (Context) AllocAlignAttr(Context, CI, Idx));
}
 
/// Check if \p AssumptionStr is a known assumption and warn if not.
static void checkAssumptionAttr(Sema &S, SourceLocation Loc,
                                StringRef AssumptionStr) {
  if (llvm::KnownAssumptionStrings.count(AssumptionStr))
    return;
 
  unsigned BestEditDistance = 3;
  StringRef Suggestion;
  for (const auto &KnownAssumptionIt : llvm::KnownAssumptionStrings) {
    unsigned EditDistance =
        AssumptionStr.edit_distance(KnownAssumptionIt.getKey());
    if (EditDistance < BestEditDistance) {
      Suggestion = KnownAssumptionIt.getKey();
      BestEditDistance = EditDistance;
    }
  }
 
  if (!Suggestion.empty())
    S.Diag(Loc, diag::warn_assume_attribute_string_unknown_suggested)
        << AssumptionStr << Suggestion;
  else
    S.Diag(Loc, diag::warn_assume_attribute_string_unknown) << AssumptionStr;
}
 
static void handleAssumumptionAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Handle the case where the attribute has a text message.
  StringRef Str;
  SourceLocation AttrStrLoc;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &AttrStrLoc))
    return;
 
  checkAssumptionAttr(S, AttrStrLoc, Str);
 
  D->addAttr(::new (S.Context) AssumptionAttr(S.Context, AL, Str));
}
 
/// Normalize the attribute, __foo__ becomes foo.
/// Returns true if normalization was applied.
static bool normalizeName(StringRef &AttrName) {
  if (AttrName.size() > 4 && AttrName.startswith("__") &&
      AttrName.endswith("__")) {
    AttrName = AttrName.drop_front(2).drop_back(2);
    return true;
  }
  return false;
}
 
static void handleOwnershipAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // This attribute must be applied to a function declaration. The first
  // argument to the attribute must be an identifier, the name of the resource,
  // for example: malloc. The following arguments must be argument indexes, the
  // arguments must be of integer type for Returns, otherwise of pointer type.
  // The difference between Holds and Takes is that a pointer may still be used
  // after being held. free() should be __attribute((ownership_takes)), whereas
  // a list append function may well be __attribute((ownership_holds)).
 
  if (!AL.isArgIdent(0)) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
        << AL << 1 << AANT_ArgumentIdentifier;
    return;
  }
 
  // Figure out our Kind.
  OwnershipAttr::OwnershipKind K =
      OwnershipAttr(S.Context, AL, nullptr, nullptr, 0).getOwnKind();
 
  // Check arguments.
  switch (K) {
  case OwnershipAttr::Takes:
  case OwnershipAttr::Holds:
    if (AL.getNumArgs() < 2) {
      S.Diag(AL.getLoc(), diag::err_attribute_too_few_arguments) << AL << 2;
      return;
    }
    break;
  case OwnershipAttr::Returns:
    if (AL.getNumArgs() > 2) {
      S.Diag(AL.getLoc(), diag::err_attribute_too_many_arguments) << AL << 1;
      return;
    }
    break;
  }
 
  IdentifierInfo *Module = AL.getArgAsIdent(0)->Ident;
 
  StringRef ModuleName = Module->getName();
  if (normalizeName(ModuleName)) {
    Module = &S.PP.getIdentifierTable().get(ModuleName);
  }
 
  SmallVector<ParamIdx, 8> OwnershipArgs;
  for (unsigned i = 1; i < AL.getNumArgs(); ++i) {
    Expr *Ex = AL.getArgAsExpr(i);
    ParamIdx Idx;
    if (!checkFunctionOrMethodParameterIndex(S, D, AL, i, Ex, Idx))
      return;
 
    // Is the function argument a pointer type?
    QualType T = getFunctionOrMethodParamType(D, Idx.getASTIndex());
    int Err = -1;  // No error
    switch (K) {
      case OwnershipAttr::Takes:
      case OwnershipAttr::Holds:
        if (!T->isAnyPointerType() && !T->isBlockPointerType())
          Err = 0;
        break;
      case OwnershipAttr::Returns:
        if (!T->isIntegerType())
          Err = 1;
        break;
    }
    if (-1 != Err) {
      S.Diag(AL.getLoc(), diag::err_ownership_type) << AL << Err
                                                    << Ex->getSourceRange();
      return;
    }
 
    // Check we don't have a conflict with another ownership attribute.
    for (const auto *I : D->specific_attrs<OwnershipAttr>()) {
      // Cannot have two ownership attributes of different kinds for the same
      // index.
      if (I->getOwnKind() != K && llvm::is_contained(I->args(), Idx)) {
        S.Diag(AL.getLoc(), diag::err_attributes_are_not_compatible) << AL << I;
        return;
      } else if (K == OwnershipAttr::Returns &&
                 I->getOwnKind() == OwnershipAttr::Returns) {
        // A returns attribute conflicts with any other returns attribute using
        // a different index.
        if (!llvm::is_contained(I->args(), Idx)) {
          S.Diag(I->getLocation(), diag::err_ownership_returns_index_mismatch)
              << I->args_begin()->getSourceIndex();
          if (I->args_size())
            S.Diag(AL.getLoc(), diag::note_ownership_returns_index_mismatch)
                << Idx.getSourceIndex() << Ex->getSourceRange();
          return;
        }
      }
    }
    OwnershipArgs.push_back(Idx);
  }
 
  ParamIdx *Start = OwnershipArgs.data();
  unsigned Size = OwnershipArgs.size();
  llvm::array_pod_sort(Start, Start + Size);
  D->addAttr(::new (S.Context)
                 OwnershipAttr(S.Context, AL, Module, Start, Size));
}
 
static void handleWeakRefAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Check the attribute arguments.
  if (AL.getNumArgs() > 1) {
    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 1;
    return;
  }
 
  // gcc rejects
  // class c {
  //   static int a __attribute__((weakref ("v2")));
  //   static int b() __attribute__((weakref ("f3")));
  // };
  // and ignores the attributes of
  // void f(void) {
  //   static int a __attribute__((weakref ("v2")));
  // }
  // we reject them
  const DeclContext *Ctx = D->getDeclContext()->getRedeclContext();
  if (!Ctx->isFileContext()) {
    S.Diag(AL.getLoc(), diag::err_attribute_weakref_not_global_context)
        << cast<NamedDecl>(D);
    return;
  }
 
  // The GCC manual says
  //
  // At present, a declaration to which `weakref' is attached can only
  // be `static'.
  //
  // It also says
  //
  // Without a TARGET,
  // given as an argument to `weakref' or to `alias', `weakref' is
  // equivalent to `weak'.
  //
  // gcc 4.4.1 will accept
  // int a7 __attribute__((weakref));
  // as
  // int a7 __attribute__((weak));
  // This looks like a bug in gcc. We reject that for now. We should revisit
  // it if this behaviour is actually used.
 
  // GCC rejects
  // static ((alias ("y"), weakref)).
  // Should we? How to check that weakref is before or after alias?
 
  // FIXME: it would be good for us to keep the WeakRefAttr as-written instead
  // of transforming it into an AliasAttr.  The WeakRefAttr never uses the
  // StringRef parameter it was given anyway.
  StringRef Str;
  if (AL.getNumArgs() && S.checkStringLiteralArgumentAttr(AL, 0, Str))
    // GCC will accept anything as the argument of weakref. Should we
    // check for an existing decl?
    D->addAttr(::new (S.Context) AliasAttr(S.Context, AL, Str));
 
  D->addAttr(::new (S.Context) WeakRefAttr(S.Context, AL));
}
 
static void handleIFuncAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  StringRef Str;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str))
    return;
 
  // Aliases should be on declarations, not definitions.
  const auto *FD = cast<FunctionDecl>(D);
  if (FD->isThisDeclarationADefinition()) {
    S.Diag(AL.getLoc(), diag::err_alias_is_definition) << FD << 1;
    return;
  }
 
  D->addAttr(::new (S.Context) IFuncAttr(S.Context, AL, Str));
}
 
static void handleAliasAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  StringRef Str;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str))
    return;
 
  if (S.Context.getTargetInfo().getTriple().isOSDarwin()) {
    S.Diag(AL.getLoc(), diag::err_alias_not_supported_on_darwin);
    return;
  }
  if (S.Context.getTargetInfo().getTriple().isNVPTX()) {
    S.Diag(AL.getLoc(), diag::err_alias_not_supported_on_nvptx);
  }
 
  // Aliases should be on declarations, not definitions.
  if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
    if (FD->isThisDeclarationADefinition()) {
      S.Diag(AL.getLoc(), diag::err_alias_is_definition) << FD << 0;
      return;
    }
  } else {
    const auto *VD = cast<VarDecl>(D);
    if (VD->isThisDeclarationADefinition() && VD->isExternallyVisible()) {
      S.Diag(AL.getLoc(), diag::err_alias_is_definition) << VD << 0;
      return;
    }
  }
 
  // Mark target used to prevent unneeded-internal-declaration warnings.
  if (!S.LangOpts.CPlusPlus) {
    // FIXME: demangle Str for C++, as the attribute refers to the mangled
    // linkage name, not the pre-mangled identifier.
    const DeclarationNameInfo target(&S.Context.Idents.get(Str), AL.getLoc());
    LookupResult LR(S, target, Sema::LookupOrdinaryName);
    if (S.LookupQualifiedName(LR, S.getCurLexicalContext()))
      for (NamedDecl *ND : LR)
        ND->markUsed(S.Context);
  }
 
  D->addAttr(::new (S.Context) AliasAttr(S.Context, AL, Str));
}
 
static void handleTLSModelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  StringRef Model;
  SourceLocation LiteralLoc;
  // Check that it is a string.
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Model, &LiteralLoc))
    return;
 
  // Check that the value.
  if (Model != "global-dynamic" && Model != "local-dynamic"
      && Model != "initial-exec" && Model != "local-exec") {
    S.Diag(LiteralLoc, diag::err_attr_tlsmodel_arg);
    return;
  }
 
  if (S.Context.getTargetInfo().getTriple().isOSAIX() &&
      Model != "global-dynamic") {
    S.Diag(LiteralLoc, diag::err_aix_attr_unsupported_tls_model) << Model;
    return;
  }
 
  D->addAttr(::new (S.Context) TLSModelAttr(S.Context, AL, Model));
}
 
static void handleRestrictAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  QualType ResultType = getFunctionOrMethodResultType(D);
  if (ResultType->isAnyPointerType() || ResultType->isBlockPointerType()) {
    D->addAttr(::new (S.Context) RestrictAttr(S.Context, AL));
    return;
  }
 
  S.Diag(AL.getLoc(), diag::warn_attribute_return_pointers_only)
      << AL << getFunctionOrMethodResultSourceRange(D);
}
 
static void handleCPUSpecificAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Ensure we don't combine these with themselves, since that causes some
  // confusing behavior.
  if (AL.getParsedKind() == ParsedAttr::AT_CPUDispatch) {
    if (checkAttrMutualExclusion<CPUSpecificAttr>(S, D, AL))
      return;
 
    if (const auto *Other = D->getAttr<CPUDispatchAttr>()) {
      S.Diag(AL.getLoc(), diag::err_disallowed_duplicate_attribute) << AL;
      S.Diag(Other->getLocation(), diag::note_conflicting_attribute);
      return;
    }
  } else if (AL.getParsedKind() == ParsedAttr::AT_CPUSpecific) {
    if (checkAttrMutualExclusion<CPUDispatchAttr>(S, D, AL))
      return;
 
    if (const auto *Other = D->getAttr<CPUSpecificAttr>()) {
      S.Diag(AL.getLoc(), diag::err_disallowed_duplicate_attribute) << AL;
      S.Diag(Other->getLocation(), diag::note_conflicting_attribute);
      return;
    }
  }
 
  FunctionDecl *FD = cast<FunctionDecl>(D);
 
  if (const auto *MD = dyn_cast<CXXMethodDecl>(D)) {
    if (MD->getParent()->isLambda()) {
      S.Diag(AL.getLoc(), diag::err_attribute_dll_lambda) << AL;
      return;
    }
  }
 
  if (!AL.checkAtLeastNumArgs(S, 1))
    return;
 
  SmallVector<IdentifierInfo *, 8> CPUs;
  for (unsigned ArgNo = 0; ArgNo < getNumAttributeArgs(AL); ++ArgNo) {
    if (!AL.isArgIdent(ArgNo)) {
      S.Diag(AL.getLoc(), diag::err_attribute_argument_type)
          << AL << AANT_ArgumentIdentifier;
      return;
    }
 
    IdentifierLoc *CPUArg = AL.getArgAsIdent(ArgNo);
    StringRef CPUName = CPUArg->Ident->getName().trim();
 
    if (!S.Context.getTargetInfo().validateCPUSpecificCPUDispatch(CPUName)) {
      S.Diag(CPUArg->Loc, diag::err_invalid_cpu_specific_dispatch_value)
          << CPUName << (AL.getKind() == ParsedAttr::AT_CPUDispatch);
      return;
    }
 
    const TargetInfo &Target = S.Context.getTargetInfo();
    if (llvm::any_of(CPUs, [CPUName, &Target](const IdentifierInfo *Cur) {
          return Target.CPUSpecificManglingCharacter(CPUName) ==
                 Target.CPUSpecificManglingCharacter(Cur->getName());
        })) {
      S.Diag(AL.getLoc(), diag::warn_multiversion_duplicate_entries);
      return;
    }
    CPUs.push_back(CPUArg->Ident);
  }
 
  FD->setIsMultiVersion(true);
  if (AL.getKind() == ParsedAttr::AT_CPUSpecific)
    D->addAttr(::new (S.Context)
                   CPUSpecificAttr(S.Context, AL, CPUs.data(), CPUs.size()));
  else
    D->addAttr(::new (S.Context)
                   CPUDispatchAttr(S.Context, AL, CPUs.data(), CPUs.size()));
}
 
static void handleCommonAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (S.LangOpts.CPlusPlus) {
    S.Diag(AL.getLoc(), diag::err_attribute_not_supported_in_lang)
        << AL << AttributeLangSupport::Cpp;
    return;
  }
 
  D->addAttr(::new (S.Context) CommonAttr(S.Context, AL));
}
 
static void handleCmseNSEntryAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (S.LangOpts.CPlusPlus && !D->getDeclContext()->isExternCContext()) {
    S.Diag(AL.getLoc(), diag::err_attribute_not_clinkage) << AL;
    return;
  }
 
  const auto *FD = cast<FunctionDecl>(D);
  if (!FD->isExternallyVisible()) {
    S.Diag(AL.getLoc(), diag::warn_attribute_cmse_entry_static);
    return;
  }
 
  D->addAttr(::new (S.Context) CmseNSEntryAttr(S.Context, AL));
}
 
static void handleNakedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (AL.isDeclspecAttribute()) {
    const auto &Triple = S.getASTContext().getTargetInfo().getTriple();
    const auto &Arch = Triple.getArch();
    if (Arch != llvm::Triple::x86 &&
        (Arch != llvm::Triple::arm && Arch != llvm::Triple::thumb)) {
      S.Diag(AL.getLoc(), diag::err_attribute_not_supported_on_arch)
          << AL << Triple.getArchName();
      return;
    }
 
    // This form is not allowed to be written on a member function (static or
    // nonstatic) when in Microsoft compatibility mode.
    if (S.getLangOpts().MSVCCompat && isa<CXXMethodDecl>(D)) {
      S.Diag(AL.getLoc(), diag::err_attribute_wrong_decl_type_str)
          << AL << "non-member functions";
      return;
    }
  }
 
  D->addAttr(::new (S.Context) NakedAttr(S.Context, AL));
}
 
static void handleNoReturnAttr(Sema &S, Decl *D, const ParsedAttr &Attrs) {
  if (hasDeclarator(D)) return;
 
  if (!isa<ObjCMethodDecl>(D)) {
    S.Diag(Attrs.getLoc(), diag::warn_attribute_wrong_decl_type)
        << Attrs << ExpectedFunctionOrMethod;
    return;
  }
 
  D->addAttr(::new (S.Context) NoReturnAttr(S.Context, Attrs));
}
 
static void handleStandardNoReturnAttr(Sema &S, Decl *D, const ParsedAttr &A) {
  // The [[_Noreturn]] spelling is deprecated in C2x, so if that was used,
  // issue an appropriate diagnostic. However, don't issue a diagnostic if the
  // attribute name comes from a macro expansion. We don't want to punish users
  // who write [[noreturn]] after including <stdnoreturn.h> (where 'noreturn'
  // is defined as a macro which expands to '_Noreturn').
  if (!S.getLangOpts().CPlusPlus &&
      A.getSemanticSpelling() == CXX11NoReturnAttr::C2x_Noreturn &&
      !(A.getLoc().isMacroID() &&
        S.getSourceManager().isInSystemMacro(A.getLoc())))
    S.Diag(A.getLoc(), diag::warn_deprecated_noreturn_spelling) << A.getRange();
 
  D->addAttr(::new (S.Context) CXX11NoReturnAttr(S.Context, A));
}
 
static void handleNoCfCheckAttr(Sema &S, Decl *D, const ParsedAttr &Attrs) {
  if (!S.getLangOpts().CFProtectionBranch)
    S.Diag(Attrs.getLoc(), diag::warn_nocf_check_attribute_ignored);
  else
    handleSimpleAttribute<AnyX86NoCfCheckAttr>(S, D, Attrs);
}
 
bool Sema::CheckAttrNoArgs(const ParsedAttr &Attrs) {
  if (!Attrs.checkExactlyNumArgs(*this, 0)) {
    Attrs.setInvalid();
    return true;
  }
 
  return false;
}
 
bool Sema::CheckAttrTarget(const ParsedAttr &AL) {
  // Check whether the attribute is valid on the current target.
  if (!AL.existsInTarget(Context.getTargetInfo())) {
    Diag(AL.getLoc(), diag::warn_unknown_attribute_ignored)
        << AL << AL.getRange();
    AL.setInvalid();
    return true;
  }
 
  return false;
}
 
static void handleAnalyzerNoReturnAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
 
  // The checking path for 'noreturn' and 'analyzer_noreturn' are different
  // because 'analyzer_noreturn' does not impact the type.
  if (!isFunctionOrMethodOrBlock(D)) {
    ValueDecl *VD = dyn_cast<ValueDecl>(D);
    if (!VD || (!VD->getType()->isBlockPointerType() &&
                !VD->getType()->isFunctionPointerType())) {
      S.Diag(AL.getLoc(), AL.isStandardAttributeSyntax()
                              ? diag::err_attribute_wrong_decl_type
                              : diag::warn_attribute_wrong_decl_type)
          << AL << ExpectedFunctionMethodOrBlock;
      return;
    }
  }
 
  D->addAttr(::new (S.Context) AnalyzerNoReturnAttr(S.Context, AL));
}
 
// PS3 PPU-specific.
static void handleVecReturnAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  /*
    Returning a Vector Class in Registers
 
    According to the PPU ABI specifications, a class with a single member of
    vector type is returned in memory when used as the return value of a
    function.
    This results in inefficient code when implementing vector classes. To return
    the value in a single vector register, add the vecreturn attribute to the
    class definition. This attribute is also applicable to struct types.
 
    Example:
 
    struct Vector
    {
      __vector float xyzw;
    } __attribute__((vecreturn));
 
    Vector Add(Vector lhs, Vector rhs)
    {
      Vector result;
      result.xyzw = vec_add(lhs.xyzw, rhs.xyzw);
      return result; // This will be returned in a register
    }
  */
  if (VecReturnAttr *A = D->getAttr<VecReturnAttr>()) {
    S.Diag(AL.getLoc(), diag::err_repeat_attribute) << A;
    return;
  }
 
  const auto *R = cast<RecordDecl>(D);
  int count = 0;
 
  if (!isa<CXXRecordDecl>(R)) {
    S.Diag(AL.getLoc(), diag::err_attribute_vecreturn_only_vector_member);
    return;
  }
 
  if (!cast<CXXRecordDecl>(R)->isPOD()) {
    S.Diag(AL.getLoc(), diag::err_attribute_vecreturn_only_pod_record);
    return;
  }
 
  for (const auto *I : R->fields()) {
    if ((count == 1) || !I->getType()->isVectorType()) {
      S.Diag(AL.getLoc(), diag::err_attribute_vecreturn_only_vector_member);
      return;
    }
    count++;
  }
 
  D->addAttr(::new (S.Context) VecReturnAttr(S.Context, AL));
}
 
static void handleDependencyAttr(Sema &S, Scope *Scope, Decl *D,
                                 const ParsedAttr &AL) {
  if (isa<ParmVarDecl>(D)) {
    // [[carries_dependency]] can only be applied to a parameter if it is a
    // parameter of a function declaration or lambda.
    if (!(Scope->getFlags() & clang::Scope::FunctionDeclarationScope)) {
      S.Diag(AL.getLoc(),
             diag::err_carries_dependency_param_not_function_decl);
      return;
    }
  }
 
  D->addAttr(::new (S.Context) CarriesDependencyAttr(S.Context, AL));
}
 
static void handleUnusedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  bool IsCXX17Attr = AL.isCXX11Attribute() && !AL.getScopeName();
 
  // If this is spelled as the standard C++17 attribute, but not in C++17, warn
  // about using it as an extension.
  if (!S.getLangOpts().CPlusPlus17 && IsCXX17Attr)
    S.Diag(AL.getLoc(), diag::ext_cxx17_attr) << AL;
 
  D->addAttr(::new (S.Context) UnusedAttr(S.Context, AL));
}
 
static void handleConstructorAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  uint32_t priority = ConstructorAttr::DefaultPriority;
  if (S.getLangOpts().HLSL && AL.getNumArgs()) {
    S.Diag(AL.getLoc(), diag::err_hlsl_init_priority_unsupported);
    return;
  }
  if (AL.getNumArgs() &&
      !checkUInt32Argument(S, AL, AL.getArgAsExpr(0), priority))
    return;
 
  D->addAttr(::new (S.Context) ConstructorAttr(S.Context, AL, priority));
}
 
static void handleDestructorAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  uint32_t priority = DestructorAttr::DefaultPriority;
  if (AL.getNumArgs() &&
      !checkUInt32Argument(S, AL, AL.getArgAsExpr(0), priority))
    return;
 
  D->addAttr(::new (S.Context) DestructorAttr(S.Context, AL, priority));
}
 
template <typename AttrTy>
static void handleAttrWithMessage(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Handle the case where the attribute has a text message.
  StringRef Str;
  if (AL.getNumArgs() == 1 && !S.checkStringLiteralArgumentAttr(AL, 0, Str))
    return;
 
  D->addAttr(::new (S.Context) AttrTy(S.Context, AL, Str));
}
 
static void handleObjCSuppresProtocolAttr(Sema &S, Decl *D,
                                          const ParsedAttr &AL) {
  if (!cast<ObjCProtocolDecl>(D)->isThisDeclarationADefinition()) {
    S.Diag(AL.getLoc(), diag::err_objc_attr_protocol_requires_definition)
        << AL << AL.getRange();
    return;
  }
 
  D->addAttr(::new (S.Context) ObjCExplicitProtocolImplAttr(S.Context, AL));
}
 
static bool checkAvailabilityAttr(Sema &S, SourceRange Range,
                                  IdentifierInfo *Platform,
                                  VersionTuple Introduced,
                                  VersionTuple Deprecated,
                                  VersionTuple Obsoleted) {
  StringRef PlatformName
    = AvailabilityAttr::getPrettyPlatformName(Platform->getName());
  if (PlatformName.empty())
    PlatformName = Platform->getName();
 
  // Ensure that Introduced <= Deprecated <= Obsoleted (although not all
  // of these steps are needed).
  if (!Introduced.empty() && !Deprecated.empty() &&
      !(Introduced <= Deprecated)) {
    S.Diag(Range.getBegin(), diag::warn_availability_version_ordering)
      << 1 << PlatformName << Deprecated.getAsString()
      << 0 << Introduced.getAsString();
    return true;
  }
 
  if (!Introduced.empty() && !Obsoleted.empty() &&
      !(Introduced <= Obsoleted)) {
    S.Diag(Range.getBegin(), diag::warn_availability_version_ordering)
      << 2 << PlatformName << Obsoleted.getAsString()
      << 0 << Introduced.getAsString();
    return true;
  }
 
  if (!Deprecated.empty() && !Obsoleted.empty() &&
      !(Deprecated <= Obsoleted)) {
    S.Diag(Range.getBegin(), diag::warn_availability_version_ordering)
      << 2 << PlatformName << Obsoleted.getAsString()
      << 1 << Deprecated.getAsString();
    return true;
  }
 
  return false;
}
 
/// Check whether the two versions match.
///
/// If either version tuple is empty, then they are assumed to match. If
/// \p BeforeIsOkay is true, then \p X can be less than or equal to \p Y.
static bool versionsMatch(const VersionTuple &X, const VersionTuple &Y,
                          bool BeforeIsOkay) {
  if (X.empty() || Y.empty())
    return true;
 
  if (X == Y)
    return true;
 
  if (BeforeIsOkay && X < Y)
    return true;
 
  return false;
}
 
AvailabilityAttr *Sema::mergeAvailabilityAttr(
    NamedDecl *D, const AttributeCommonInfo &CI, IdentifierInfo *Platform,
    bool Implicit, VersionTuple Introduced, VersionTuple Deprecated,
    VersionTuple Obsoleted, bool IsUnavailable, StringRef Message,
    bool IsStrict, StringRef Replacement, AvailabilityMergeKind AMK,
    int Priority) {
  VersionTuple MergedIntroduced = Introduced;
  VersionTuple MergedDeprecated = Deprecated;
  VersionTuple MergedObsoleted = Obsoleted;
  bool FoundAny = false;
  bool OverrideOrImpl = false;
  switch (AMK) {
  case AMK_None:
  case AMK_Redeclaration:
    OverrideOrImpl = false;
    break;
 
  case AMK_Override:
  case AMK_ProtocolImplementation:
  case AMK_OptionalProtocolImplementation:
    OverrideOrImpl = true;
    break;
  }
 
  if (D->hasAttrs()) {
    AttrVec &Attrs = D->getAttrs();
    for (unsigned i = 0, e = Attrs.size(); i != e;) {
      const auto *OldAA = dyn_cast<AvailabilityAttr>(Attrs[i]);
      if (!OldAA) {
        ++i;
        continue;
      }
 
      IdentifierInfo *OldPlatform = OldAA->getPlatform();
      if (OldPlatform != Platform) {
        ++i;
        continue;
      }
 
      // If there is an existing availability attribute for this platform that
      // has a lower priority use the existing one and discard the new
      // attribute.
      if (OldAA->getPriority() < Priority)
        return nullptr;
 
      // If there is an existing attribute for this platform that has a higher
      // priority than the new attribute then erase the old one and continue
      // processing the attributes.
      if (OldAA->getPriority() > Priority) {
        Attrs.erase(Attrs.begin() + i);
        --e;
        continue;
      }
 
      FoundAny = true;
      VersionTuple OldIntroduced = OldAA->getIntroduced();
      VersionTuple OldDeprecated = OldAA->getDeprecated();
      VersionTuple OldObsoleted = OldAA->getObsoleted();
      bool OldIsUnavailable = OldAA->getUnavailable();
 
      if (!versionsMatch(OldIntroduced, Introduced, OverrideOrImpl) ||
          !versionsMatch(Deprecated, OldDeprecated, OverrideOrImpl) ||
          !versionsMatch(Obsoleted, OldObsoleted, OverrideOrImpl) ||
          !(OldIsUnavailable == IsUnavailable ||
            (OverrideOrImpl && !OldIsUnavailable && IsUnavailable))) {
        if (OverrideOrImpl) {
          int Which = -1;
          VersionTuple FirstVersion;
          VersionTuple SecondVersion;
          if (!versionsMatch(OldIntroduced, Introduced, OverrideOrImpl)) {
            Which = 0;
            FirstVersion = OldIntroduced;
            SecondVersion = Introduced;
          } else if (!versionsMatch(Deprecated, OldDeprecated, OverrideOrImpl)) {
            Which = 1;
            FirstVersion = Deprecated;
            SecondVersion = OldDeprecated;
          } else if (!versionsMatch(Obsoleted, OldObsoleted, OverrideOrImpl)) {
            Which = 2;
            FirstVersion = Obsoleted;
            SecondVersion = OldObsoleted;
          }
 
          if (Which == -1) {
            Diag(OldAA->getLocation(),
                 diag::warn_mismatched_availability_override_unavail)
              << AvailabilityAttr::getPrettyPlatformName(Platform->getName())
              << (AMK == AMK_Override);
          } else if (Which != 1 && AMK == AMK_OptionalProtocolImplementation) {
            // Allow different 'introduced' / 'obsoleted' availability versions
            // on a method that implements an optional protocol requirement. It
            // makes less sense to allow this for 'deprecated' as the user can't
            // see if the method is 'deprecated' as 'respondsToSelector' will
            // still return true when the method is deprecated.
            ++i;
            continue;
          } else {
            Diag(OldAA->getLocation(),
                 diag::warn_mismatched_availability_override)
              << Which
              << AvailabilityAttr::getPrettyPlatformName(Platform->getName())
              << FirstVersion.getAsString() << SecondVersion.getAsString()
              << (AMK == AMK_Override);
          }
          if (AMK == AMK_Override)
            Diag(CI.getLoc(), diag::note_overridden_method);
          else
            Diag(CI.getLoc(), diag::note_protocol_method);
        } else {
          Diag(OldAA->getLocation(), diag::warn_mismatched_availability);
          Diag(CI.getLoc(), diag::note_previous_attribute);
        }
 
        Attrs.erase(Attrs.begin() + i);
        --e;
        continue;
      }
 
      VersionTuple MergedIntroduced2 = MergedIntroduced;
      VersionTuple MergedDeprecated2 = MergedDeprecated;
      VersionTuple MergedObsoleted2 = MergedObsoleted;
 
      if (MergedIntroduced2.empty())
        MergedIntroduced2 = OldIntroduced;
      if (MergedDeprecated2.empty())
        MergedDeprecated2 = OldDeprecated;
      if (MergedObsoleted2.empty())
        MergedObsoleted2 = OldObsoleted;
 
      if (checkAvailabilityAttr(*this, OldAA->getRange(), Platform,
                                MergedIntroduced2, MergedDeprecated2,
                                MergedObsoleted2)) {
        Attrs.erase(Attrs.begin() + i);
        --e;
        continue;
      }
 
      MergedIntroduced = MergedIntroduced2;
      MergedDeprecated = MergedDeprecated2;
      MergedObsoleted = MergedObsoleted2;
      ++i;
    }
  }
 
  if (FoundAny &&
      MergedIntroduced == Introduced &&
      MergedDeprecated == Deprecated &&
      MergedObsoleted == Obsoleted)
    return nullptr;
 
  // Only create a new attribute if !OverrideOrImpl, but we want to do
  // the checking.
  if (!checkAvailabilityAttr(*this, CI.getRange(), Platform, MergedIntroduced,
                             MergedDeprecated, MergedObsoleted) &&
      !OverrideOrImpl) {
    auto *Avail = ::new (Context) AvailabilityAttr(
        Context, CI, Platform, Introduced, Deprecated, Obsoleted, IsUnavailable,
        Message, IsStrict, Replacement, Priority);
    Avail->setImplicit(Implicit);
    return Avail;
  }
  return nullptr;
}
 
static void handleAvailabilityAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (isa<UsingDecl, UnresolvedUsingTypenameDecl, UnresolvedUsingValueDecl>(
          D)) {
    S.Diag(AL.getRange().getBegin(), diag::warn_deprecated_ignored_on_using)
        << AL;
    return;
  }
 
  if (!AL.checkExactlyNumArgs(S, 1))
    return;
  IdentifierLoc *Platform = AL.getArgAsIdent(0);
 
  IdentifierInfo *II = Platform->Ident;
  if (AvailabilityAttr::getPrettyPlatformName(II->getName()).empty())
    S.Diag(Platform->Loc, diag::warn_availability_unknown_platform)
      << Platform->Ident;
 
  auto *ND = dyn_cast<NamedDecl>(D);
  if (!ND) // We warned about this already, so just return.
    return;
 
  AvailabilityChange Introduced = AL.getAvailabilityIntroduced();
  AvailabilityChange Deprecated = AL.getAvailabilityDeprecated();
  AvailabilityChange Obsoleted = AL.getAvailabilityObsoleted();
  bool IsUnavailable = AL.getUnavailableLoc().isValid();
  bool IsStrict = AL.getStrictLoc().isValid();
  StringRef Str;
  if (const auto *SE = dyn_cast_or_null<StringLiteral>(AL.getMessageExpr()))
    Str = SE->getString();
  StringRef Replacement;
  if (const auto *SE = dyn_cast_or_null<StringLiteral>(AL.getReplacementExpr()))
    Replacement = SE->getString();
 
  if (II->isStr("swift")) {
    if (Introduced.isValid() || Obsoleted.isValid() ||
        (!IsUnavailable && !Deprecated.isValid())) {
      S.Diag(AL.getLoc(),
             diag::warn_availability_swift_unavailable_deprecated_only);
      return;
    }
  }
 
  if (II->isStr("fuchsia")) {
    std::optional<unsigned> Min, Sub;
    if ((Min = Introduced.Version.getMinor()) ||
        (Sub = Introduced.Version.getSubminor())) {
      S.Diag(AL.getLoc(), diag::warn_availability_fuchsia_unavailable_minor);
      return;
    }
  }
 
  int PriorityModifier = AL.isPragmaClangAttribute()
                             ? Sema::AP_PragmaClangAttribute
                             : Sema::AP_Explicit;
  AvailabilityAttr *NewAttr = S.mergeAvailabilityAttr(
      ND, AL, II, false /*Implicit*/, Introduced.Version, Deprecated.Version,
      Obsoleted.Version, IsUnavailable, Str, IsStrict, Replacement,
      Sema::AMK_None, PriorityModifier);
  if (NewAttr)
    D->addAttr(NewAttr);
 
  // Transcribe "ios" to "watchos" (and add a new attribute) if the versioning
  // matches before the start of the watchOS platform.
  if (S.Context.getTargetInfo().getTriple().isWatchOS()) {
    IdentifierInfo *NewII = nullptr;
    if (II->getName() == "ios")
      NewII = &S.Context.Idents.get("watchos");
    else if (II->getName() == "ios_app_extension")
      NewII = &S.Context.Idents.get("watchos_app_extension");
 
    if (NewII) {
      const auto *SDKInfo = S.getDarwinSDKInfoForAvailabilityChecking();
      const auto *IOSToWatchOSMapping =
          SDKInfo ? SDKInfo->getVersionMapping(
                        DarwinSDKInfo::OSEnvPair::iOStoWatchOSPair())
                  : nullptr;
 
      auto adjustWatchOSVersion =
          [IOSToWatchOSMapping](VersionTuple Version) -> VersionTuple {
        if (Version.empty())
          return Version;
        auto MinimumWatchOSVersion = VersionTuple(2, 0);
 
        if (IOSToWatchOSMapping) {
          if (auto MappedVersion = IOSToWatchOSMapping->map(
                  Version, MinimumWatchOSVersion, std::nullopt)) {
            return *MappedVersion;
          }
        }
 
        auto Major = Version.getMajor();
        auto NewMajor = Major >= 9 ? Major - 7 : 0;
        if (NewMajor >= 2) {
          if (Version.getMinor()) {
            if (Version.getSubminor())
              return VersionTuple(NewMajor, *Version.getMinor(),
                                  *Version.getSubminor());
            else
              return VersionTuple(NewMajor, *Version.getMinor());
          }
          return VersionTuple(NewMajor);
        }
 
        return MinimumWatchOSVersion;
      };
 
      auto NewIntroduced = adjustWatchOSVersion(Introduced.Version);
      auto NewDeprecated = adjustWatchOSVersion(Deprecated.Version);
      auto NewObsoleted = adjustWatchOSVersion(Obsoleted.Version);
 
      AvailabilityAttr *NewAttr = S.mergeAvailabilityAttr(
          ND, AL, NewII, true /*Implicit*/, NewIntroduced, NewDeprecated,
          NewObsoleted, IsUnavailable, Str, IsStrict, Replacement,
          Sema::AMK_None,
          PriorityModifier + Sema::AP_InferredFromOtherPlatform);
      if (NewAttr)
        D->addAttr(NewAttr);
    }
  } else if (S.Context.getTargetInfo().getTriple().isTvOS()) {
    // Transcribe "ios" to "tvos" (and add a new attribute) if the versioning
    // matches before the start of the tvOS platform.
    IdentifierInfo *NewII = nullptr;
    if (II->getName() == "ios")
      NewII = &S.Context.Idents.get("tvos");
    else if (II->getName() == "ios_app_extension")
      NewII = &S.Context.Idents.get("tvos_app_extension");
 
    if (NewII) {
      const auto *SDKInfo = S.getDarwinSDKInfoForAvailabilityChecking();
      const auto *IOSToTvOSMapping =
          SDKInfo ? SDKInfo->getVersionMapping(
                        DarwinSDKInfo::OSEnvPair::iOStoTvOSPair())
                  : nullptr;
 
      auto AdjustTvOSVersion =
          [IOSToTvOSMapping](VersionTuple Version) -> VersionTuple {
        if (Version.empty())
          return Version;
 
        if (IOSToTvOSMapping) {
          if (auto MappedVersion = IOSToTvOSMapping->map(
                  Version, VersionTuple(0, 0), std::nullopt)) {
            return *MappedVersion;
          }
        }
        return Version;
      };
 
      auto NewIntroduced = AdjustTvOSVersion(Introduced.Version);
      auto NewDeprecated = AdjustTvOSVersion(Deprecated.Version);
      auto NewObsoleted = AdjustTvOSVersion(Obsoleted.Version);
 
      AvailabilityAttr *NewAttr = S.mergeAvailabilityAttr(
          ND, AL, NewII, true /*Implicit*/, NewIntroduced, NewDeprecated,
          NewObsoleted, IsUnavailable, Str, IsStrict, Replacement,
          Sema::AMK_None,
          PriorityModifier + Sema::AP_InferredFromOtherPlatform);
      if (NewAttr)
        D->addAttr(NewAttr);
    }
  } else if (S.Context.getTargetInfo().getTriple().getOS() ==
                 llvm::Triple::IOS &&
             S.Context.getTargetInfo().getTriple().isMacCatalystEnvironment()) {
    auto GetSDKInfo = [&]() {
      return S.getDarwinSDKInfoForAvailabilityChecking(AL.getRange().getBegin(),
                                                       "macOS");
    };
 
    // Transcribe "ios" to "maccatalyst" (and add a new attribute).
    IdentifierInfo *NewII = nullptr;
    if (II->getName() == "ios")
      NewII = &S.Context.Idents.get("maccatalyst");
    else if (II->getName() == "ios_app_extension")
      NewII = &S.Context.Idents.get("maccatalyst_app_extension");
    if (NewII) {
      auto MinMacCatalystVersion = [](const VersionTuple &V) {
        if (V.empty())
          return V;
        if (V.getMajor() < 13 ||
            (V.getMajor() == 13 && V.getMinor() && *V.getMinor() < 1))
          return VersionTuple(13, 1); // The min Mac Catalyst version is 13.1.
        return V;
      };
      AvailabilityAttr *NewAttr = S.mergeAvailabilityAttr(
          ND, AL.getRange(), NewII, true /*Implicit*/,
          MinMacCatalystVersion(Introduced.Version),
          MinMacCatalystVersion(Deprecated.Version),
          MinMacCatalystVersion(Obsoleted.Version), IsUnavailable, Str,
          IsStrict, Replacement, Sema::AMK_None,
          PriorityModifier + Sema::AP_InferredFromOtherPlatform);
      if (NewAttr)
        D->addAttr(NewAttr);
    } else if (II->getName() == "macos" && GetSDKInfo() &&
               (!Introduced.Version.empty() || !Deprecated.Version.empty() ||
                !Obsoleted.Version.empty())) {
      if (const auto *MacOStoMacCatalystMapping =
              GetSDKInfo()->getVersionMapping(
                  DarwinSDKInfo::OSEnvPair::macOStoMacCatalystPair())) {
        // Infer Mac Catalyst availability from the macOS availability attribute
        // if it has versioned availability. Don't infer 'unavailable'. This
        // inferred availability has lower priority than the other availability
        // attributes that are inferred from 'ios'.
        NewII = &S.Context.Idents.get("maccatalyst");
        auto RemapMacOSVersion =
            [&](const VersionTuple &V) -> std::optional<VersionTuple> {
          if (V.empty())
            return std::nullopt;
          // API_TO_BE_DEPRECATED is 100000.
          if (V.getMajor() == 100000)
            return VersionTuple(100000);
          // The minimum iosmac version is 13.1
          return MacOStoMacCatalystMapping->map(V, VersionTuple(13, 1),
                                                std::nullopt);
        };
        std::optional<VersionTuple> NewIntroduced =
                                        RemapMacOSVersion(Introduced.Version),
                                    NewDeprecated =
                                        RemapMacOSVersion(Deprecated.Version),
                                    NewObsoleted =
                                        RemapMacOSVersion(Obsoleted.Version);
        if (NewIntroduced || NewDeprecated || NewObsoleted) {
          auto VersionOrEmptyVersion =
              [](const std::optional<VersionTuple> &V) -> VersionTuple {
            return V ? *V : VersionTuple();
          };
          AvailabilityAttr *NewAttr = S.mergeAvailabilityAttr(
              ND, AL.getRange(), NewII, true /*Implicit*/,
              VersionOrEmptyVersion(NewIntroduced),
              VersionOrEmptyVersion(NewDeprecated),
              VersionOrEmptyVersion(NewObsoleted), /*IsUnavailable=*/false, Str,
              IsStrict, Replacement, Sema::AMK_None,
              PriorityModifier + Sema::AP_InferredFromOtherPlatform +
                  Sema::AP_InferredFromOtherPlatform);
          if (NewAttr)
            D->addAttr(NewAttr);
        }
      }
    }
  }
}
 
static void handleExternalSourceSymbolAttr(Sema &S, Decl *D,
                                           const ParsedAttr &AL) {
  if (!AL.checkAtLeastNumArgs(S, 1) || !AL.checkAtMostNumArgs(S, 4))
    return;
 
  StringRef Language;
  if (const auto *SE = dyn_cast_or_null<StringLiteral>(AL.getArgAsExpr(0)))
    Language = SE->getString();
  StringRef DefinedIn;
  if (const auto *SE = dyn_cast_or_null<StringLiteral>(AL.getArgAsExpr(1)))
    DefinedIn = SE->getString();
  bool IsGeneratedDeclaration = AL.getArgAsIdent(2) != nullptr;
  StringRef USR;
  if (const auto *SE = dyn_cast_or_null<StringLiteral>(AL.getArgAsExpr(3)))
    USR = SE->getString();
 
  D->addAttr(::new (S.Context) ExternalSourceSymbolAttr(
      S.Context, AL, Language, DefinedIn, IsGeneratedDeclaration, USR));
}
 
template <class T>
static T *mergeVisibilityAttr(Sema &S, Decl *D, const AttributeCommonInfo &CI,
                              typename T::VisibilityType value) {
  T *existingAttr = D->getAttr<T>();
  if (existingAttr) {
    typename T::VisibilityType existingValue = existingAttr->getVisibility();
    if (existingValue == value)
      return nullptr;
    S.Diag(existingAttr->getLocation(), diag::err_mismatched_visibility);
    S.Diag(CI.getLoc(), diag::note_previous_attribute);
    D->dropAttr<T>();
  }
  return ::new (S.Context) T(S.Context, CI, value);
}
 
VisibilityAttr *Sema::mergeVisibilityAttr(Decl *D,
                                          const AttributeCommonInfo &CI,
                                          VisibilityAttr::VisibilityType Vis) {
  return ::mergeVisibilityAttr<VisibilityAttr>(*this, D, CI, Vis);
}
 
TypeVisibilityAttr *
Sema::mergeTypeVisibilityAttr(Decl *D, const AttributeCommonInfo &CI,
                              TypeVisibilityAttr::VisibilityType Vis) {
  return ::mergeVisibilityAttr<TypeVisibilityAttr>(*this, D, CI, Vis);
}
 
static void handleVisibilityAttr(Sema &S, Decl *D, const ParsedAttr &AL,
                                 bool isTypeVisibility) {
  // Visibility attributes don't mean anything on a typedef.
  if (isa<TypedefNameDecl>(D)) {
    S.Diag(AL.getRange().getBegin(), diag::warn_attribute_ignored) << AL;
    return;
  }
 
  // 'type_visibility' can only go on a type or namespace.
  if (isTypeVisibility &&
      !(isa<TagDecl>(D) ||
        isa<ObjCInterfaceDecl>(D) ||
        isa<NamespaceDecl>(D))) {
    S.Diag(AL.getRange().getBegin(), diag::err_attribute_wrong_decl_type)
        << AL << ExpectedTypeOrNamespace;
    return;
  }
 
  // Check that the argument is a string literal.
  StringRef TypeStr;
  SourceLocation LiteralLoc;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, TypeStr, &LiteralLoc))
    return;
 
  VisibilityAttr::VisibilityType type;
  if (!VisibilityAttr::ConvertStrToVisibilityType(TypeStr, type)) {
    S.Diag(LiteralLoc, diag::warn_attribute_type_not_supported) << AL
                                                                << TypeStr;
    return;
  }
 
  // Complain about attempts to use protected visibility on targets
  // (like Darwin) that don't support it.
  if (type == VisibilityAttr::Protected &&
      !S.Context.getTargetInfo().hasProtectedVisibility()) {
    S.Diag(AL.getLoc(), diag::warn_attribute_protected_visibility);
    type = VisibilityAttr::Default;
  }
 
  Attr *newAttr;
  if (isTypeVisibility) {
    newAttr = S.mergeTypeVisibilityAttr(
        D, AL, (TypeVisibilityAttr::VisibilityType)type);
  } else {
    newAttr = S.mergeVisibilityAttr(D, AL, type);
  }
  if (newAttr)
    D->addAttr(newAttr);
}
 
static void handleObjCDirectAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // objc_direct cannot be set on methods declared in the context of a protocol
  if (isa<ObjCProtocolDecl>(D->getDeclContext())) {
    S.Diag(AL.getLoc(), diag::err_objc_direct_on_protocol) << false;
    return;
  }
 
  if (S.getLangOpts().ObjCRuntime.allowsDirectDispatch()) {
    handleSimpleAttribute<ObjCDirectAttr>(S, D, AL);
  } else {
    S.Diag(AL.getLoc(), diag::warn_objc_direct_ignored) << AL;
  }
}
 
static void handleObjCDirectMembersAttr(Sema &S, Decl *D,
                                        const ParsedAttr &AL) {
  if (S.getLangOpts().ObjCRuntime.allowsDirectDispatch()) {
    handleSimpleAttribute<ObjCDirectMembersAttr>(S, D, AL);
  } else {
    S.Diag(AL.getLoc(), diag::warn_objc_direct_ignored) << AL;
  }
}
 
static void handleObjCMethodFamilyAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  const auto *M = cast<ObjCMethodDecl>(D);
  if (!AL.isArgIdent(0)) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
        << AL << 1 << AANT_ArgumentIdentifier;
    return;
  }
 
  IdentifierLoc *IL = AL.getArgAsIdent(0);
  ObjCMethodFamilyAttr::FamilyKind F;
  if (!ObjCMethodFamilyAttr::ConvertStrToFamilyKind(IL->Ident->getName(), F)) {
    S.Diag(IL->Loc, diag::warn_attribute_type_not_supported) << AL << IL->Ident;
    return;
  }
 
  if (F == ObjCMethodFamilyAttr::OMF_init &&
      !M->getReturnType()->isObjCObjectPointerType()) {
    S.Diag(M->getLocation(), diag::err_init_method_bad_return_type)
        << M->getReturnType();
    // Ignore the attribute.
    return;
  }
 
  D->addAttr(new (S.Context) ObjCMethodFamilyAttr(S.Context, AL, F));
}
 
static void handleObjCNSObject(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (const auto *TD = dyn_cast<TypedefNameDecl>(D)) {
    QualType T = TD->getUnderlyingType();
    if (!T->isCARCBridgableType()) {
      S.Diag(TD->getLocation(), diag::err_nsobject_attribute);
      return;
    }
  }
  else if (const auto *PD = dyn_cast<ObjCPropertyDecl>(D)) {
    QualType T = PD->getType();
    if (!T->isCARCBridgableType()) {
      S.Diag(PD->getLocation(), diag::err_nsobject_attribute);
      return;
    }
  }
  else {
    // It is okay to include this attribute on properties, e.g.:
    //
    //  @property (retain, nonatomic) struct Bork *Q __attribute__((NSObject));
    //
    // In this case it follows tradition and suppresses an error in the above
    // case.
    S.Diag(D->getLocation(), diag::warn_nsobject_attribute);
  }
  D->addAttr(::new (S.Context) ObjCNSObjectAttr(S.Context, AL));
}
 
static void handleObjCIndependentClass(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (const auto *TD = dyn_cast<TypedefNameDecl>(D)) {
    QualType T = TD->getUnderlyingType();
    if (!T->isObjCObjectPointerType()) {
      S.Diag(TD->getLocation(), diag::warn_ptr_independentclass_attribute);
      return;
    }
  } else {
    S.Diag(D->getLocation(), diag::warn_independentclass_attribute);
    return;
  }
  D->addAttr(::new (S.Context) ObjCIndependentClassAttr(S.Context, AL));
}
 
static void handleBlocksAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!AL.isArgIdent(0)) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
        << AL << 1 << AANT_ArgumentIdentifier;
    return;
  }
 
  IdentifierInfo *II = AL.getArgAsIdent(0)->Ident;
  BlocksAttr::BlockType type;
  if (!BlocksAttr::ConvertStrToBlockType(II->getName(), type)) {
    S.Diag(AL.getLoc(), diag::warn_attribute_type_not_supported) << AL << II;
    return;
  }
 
  D->addAttr(::new (S.Context) BlocksAttr(S.Context, AL, type));
}
 
static void handleSentinelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  unsigned sentinel = (unsigned)SentinelAttr::DefaultSentinel;
  if (AL.getNumArgs() > 0) {
    Expr *E = AL.getArgAsExpr(0);
    std::optional<llvm::APSInt> Idx = llvm::APSInt(32);
    if (E->isTypeDependent() || !(Idx = E->getIntegerConstantExpr(S.Context))) {
      S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
          << AL << 1 << AANT_ArgumentIntegerConstant << E->getSourceRange();
      return;
    }
 
    if (Idx->isSigned() && Idx->isNegative()) {
      S.Diag(AL.getLoc(), diag::err_attribute_sentinel_less_than_zero)
        << E->getSourceRange();
      return;
    }
 
    sentinel = Idx->getZExtValue();
  }
 
  unsigned nullPos = (unsigned)SentinelAttr::DefaultNullPos;
  if (AL.getNumArgs() > 1) {
    Expr *E = AL.getArgAsExpr(1);
    std::optional<llvm::APSInt> Idx = llvm::APSInt(32);
    if (E->isTypeDependent() || !(Idx = E->getIntegerConstantExpr(S.Context))) {
      S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
          << AL << 2 << AANT_ArgumentIntegerConstant << E->getSourceRange();
      return;
    }
    nullPos = Idx->getZExtValue();
 
    if ((Idx->isSigned() && Idx->isNegative()) || nullPos > 1) {
      // FIXME: This error message could be improved, it would be nice
      // to say what the bounds actually are.
      S.Diag(AL.getLoc(), diag::err_attribute_sentinel_not_zero_or_one)
        << E->getSourceRange();
      return;
    }
  }
 
  if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
    const FunctionType *FT = FD->getType()->castAs<FunctionType>();
    if (isa<FunctionNoProtoType>(FT)) {
      S.Diag(AL.getLoc(), diag::warn_attribute_sentinel_named_arguments);
      return;
    }
 
    if (!cast<FunctionProtoType>(FT)->isVariadic()) {
      S.Diag(AL.getLoc(), diag::warn_attribute_sentinel_not_variadic) << 0;
      return;
    }
  } else if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
    if (!MD->isVariadic()) {
      S.Diag(AL.getLoc(), diag::warn_attribute_sentinel_not_variadic) << 0;
      return;
    }
  } else if (const auto *BD = dyn_cast<BlockDecl>(D)) {
    if (!BD->isVariadic()) {
      S.Diag(AL.getLoc(), diag::warn_attribute_sentinel_not_variadic) << 1;
      return;
    }
  } else if (const auto *V = dyn_cast<VarDecl>(D)) {
    QualType Ty = V->getType();
    if (Ty->isBlockPointerType() || Ty->isFunctionPointerType()) {
      const FunctionType *FT = Ty->isFunctionPointerType()
                                   ? D->getFunctionType()
                                   : Ty->castAs<BlockPointerType>()
                                         ->getPointeeType()
                                         ->castAs<FunctionType>();
      if (!cast<FunctionProtoType>(FT)->isVariadic()) {
        int m = Ty->isFunctionPointerType() ? 0 : 1;
        S.Diag(AL.getLoc(), diag::warn_attribute_sentinel_not_variadic) << m;
        return;
      }
    } else {
      S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type)
          << AL << ExpectedFunctionMethodOrBlock;
      return;
    }
  } else {
    S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type)
        << AL << ExpectedFunctionMethodOrBlock;
    return;
  }
  D->addAttr(::new (S.Context) SentinelAttr(S.Context, AL, sentinel, nullPos));
}
 
static void handleWarnUnusedResult(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (D->getFunctionType() &&
      D->getFunctionType()->getReturnType()->isVoidType() &&
      !isa<CXXConstructorDecl>(D)) {
    S.Diag(AL.getLoc(), diag::warn_attribute_void_function_method) << AL << 0;
    return;
  }
  if (const auto *MD = dyn_cast<ObjCMethodDecl>(D))
    if (MD->getReturnType()->isVoidType()) {
      S.Diag(AL.getLoc(), diag::warn_attribute_void_function_method) << AL << 1;
      return;
    }
 
  StringRef Str;
  if (AL.isStandardAttributeSyntax() && !AL.getScopeName()) {
    // The standard attribute cannot be applied to variable declarations such
    // as a function pointer.
    if (isa<VarDecl>(D))
      S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type_str)
          << AL << "functions, classes, or enumerations";
 
    // If this is spelled as the standard C++17 attribute, but not in C++17,
    // warn about using it as an extension. If there are attribute arguments,
    // then claim it's a C++2a extension instead.
    // FIXME: If WG14 does not seem likely to adopt the same feature, add an
    // extension warning for C2x mode.
    const LangOptions &LO = S.getLangOpts();
    if (AL.getNumArgs() == 1) {
      if (LO.CPlusPlus && !LO.CPlusPlus20)
        S.Diag(AL.getLoc(), diag::ext_cxx20_attr) << AL;
 
      // Since this is spelled [[nodiscard]], get the optional string
      // literal. If in C++ mode, but not in C++2a mode, diagnose as an
      // extension.
      // FIXME: C2x should support this feature as well, even as an extension.
      if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, nullptr))
        return;
    } else if (LO.CPlusPlus && !LO.CPlusPlus17)
      S.Diag(AL.getLoc(), diag::ext_cxx17_attr) << AL;
  }
 
  if ((!AL.isGNUAttribute() &&
       !(AL.isStandardAttributeSyntax() && AL.isClangScope())) &&
      isa<TypedefNameDecl>(D)) {
    S.Diag(AL.getLoc(), diag::warn_unused_result_typedef_unsupported_spelling)
        << AL.isGNUScope();
    return;
  }
 
  D->addAttr(::new (S.Context) WarnUnusedResultAttr(S.Context, AL, Str));
}
 
static void handleWeakImportAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // weak_import only applies to variable & function declarations.
  bool isDef = false;
  if (!D->canBeWeakImported(isDef)) {
    if (isDef)
      S.Diag(AL.getLoc(), diag::warn_attribute_invalid_on_definition)
        << "weak_import";
    else if (isa<ObjCPropertyDecl>(D) || isa<ObjCMethodDecl>(D) ||
             (S.Context.getTargetInfo().getTriple().isOSDarwin() &&
              (isa<ObjCInterfaceDecl>(D) || isa<EnumDecl>(D)))) {
      // Nothing to warn about here.
    } else
      S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type)
          << AL << ExpectedVariableOrFunction;
 
    return;
  }
 
  D->addAttr(::new (S.Context) WeakImportAttr(S.Context, AL));
}
 
// Handles reqd_work_group_size and work_group_size_hint.
template <typename WorkGroupAttr>
static void handleWorkGroupSize(Sema &S, Decl *D, const ParsedAttr &AL) {
  uint32_t WGSize[3];
  for (unsigned i = 0; i < 3; ++i) {
    const Expr *E = AL.getArgAsExpr(i);
    if (!checkUInt32Argument(S, AL, E, WGSize[i], i,
                             /*StrictlyUnsigned=*/true))
      return;
    if (WGSize[i] == 0) {
      S.Diag(AL.getLoc(), diag::err_attribute_argument_is_zero)
          << AL << E->getSourceRange();
      return;
    }
  }
 
  WorkGroupAttr *Existing = D->getAttr<WorkGroupAttr>();
  if (Existing && !(Existing->getXDim() == WGSize[0] &&
                    Existing->getYDim() == WGSize[1] &&
                    Existing->getZDim() == WGSize[2]))
    S.Diag(AL.getLoc(), diag::warn_duplicate_attribute) << AL;
 
  D->addAttr(::new (S.Context)
                 WorkGroupAttr(S.Context, AL, WGSize[0], WGSize[1], WGSize[2]));
}
 
// Handles intel_reqd_sub_group_size.
static void handleSubGroupSize(Sema &S, Decl *D, const ParsedAttr &AL) {
  uint32_t SGSize;
  const Expr *E = AL.getArgAsExpr(0);
  if (!checkUInt32Argument(S, AL, E, SGSize))
    return;
  if (SGSize == 0) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_is_zero)
        << AL << E->getSourceRange();
    return;
  }
 
  OpenCLIntelReqdSubGroupSizeAttr *Existing =
      D->getAttr<OpenCLIntelReqdSubGroupSizeAttr>();
  if (Existing && Existing->getSubGroupSize() != SGSize)
    S.Diag(AL.getLoc(), diag::warn_duplicate_attribute) << AL;
 
  D->addAttr(::new (S.Context)
                 OpenCLIntelReqdSubGroupSizeAttr(S.Context, AL, SGSize));
}
 
static void handleVecTypeHint(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!AL.hasParsedType()) {
    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 1;
    return;
  }
 
  TypeSourceInfo *ParmTSI = nullptr;
  QualType ParmType = S.GetTypeFromParser(AL.getTypeArg(), &ParmTSI);
  assert(ParmTSI && "no type source info for attribute argument");
 
  if (!ParmType->isExtVectorType() && !ParmType->isFloatingType() &&
      (ParmType->isBooleanType() ||
       !ParmType->isIntegralType(S.getASTContext()))) {
    S.Diag(AL.getLoc(), diag::err_attribute_invalid_argument) << 2 << AL;
    return;
  }
 
  if (VecTypeHintAttr *A = D->getAttr<VecTypeHintAttr>()) {
    if (!S.Context.hasSameType(A->getTypeHint(), ParmType)) {
      S.Diag(AL.getLoc(), diag::warn_duplicate_attribute) << AL;
      return;
    }
  }
 
  D->addAttr(::new (S.Context) VecTypeHintAttr(S.Context, AL, ParmTSI));
}
 
SectionAttr *Sema::mergeSectionAttr(Decl *D, const AttributeCommonInfo &CI,
                                    StringRef Name) {
  // Explicit or partial specializations do not inherit
  // the section attribute from the primary template.
  if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
    if (CI.getAttributeSpellingListIndex() == SectionAttr::Declspec_allocate &&
        FD->isFunctionTemplateSpecialization())
      return nullptr;
  }
  if (SectionAttr *ExistingAttr = D->getAttr<SectionAttr>()) {
    if (ExistingAttr->getName() == Name)
      return nullptr;
    Diag(ExistingAttr->getLocation(), diag::warn_mismatched_section)
         << 1 /*section*/;
    Diag(CI.getLoc(), diag::note_previous_attribute);
    return nullptr;
  }
  return ::new (Context) SectionAttr(Context, CI, Name);
}
 
/// Used to implement to perform semantic checking on
/// attribute((section("foo"))) specifiers.
///
/// In this case, "foo" is passed in to be checked.  If the section
/// specifier is invalid, return an Error that indicates the problem.
///
/// This is a simple quality of implementation feature to catch errors
/// and give good diagnostics in cases when the assembler or code generator
/// would otherwise reject the section specifier.
llvm::Error Sema::isValidSectionSpecifier(StringRef SecName) {
  if (!Context.getTargetInfo().getTriple().isOSDarwin())
    return llvm::Error::success();
 
  // Let MCSectionMachO validate this.
  StringRef Segment, Section;
  unsigned TAA, StubSize;
  bool HasTAA;
  return llvm::MCSectionMachO::ParseSectionSpecifier(SecName, Segment, Section,
                                                     TAA, HasTAA, StubSize);
}
 
bool Sema::checkSectionName(SourceLocation LiteralLoc, StringRef SecName) {
  if (llvm::Error E = isValidSectionSpecifier(SecName)) {
    Diag(LiteralLoc, diag::err_attribute_section_invalid_for_target)
        << toString(std::move(E)) << 1 /*'section'*/;
    return false;
  }
  return true;
}
 
static void handleSectionAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Make sure that there is a string literal as the sections's single
  // argument.
  StringRef Str;
  SourceLocation LiteralLoc;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &LiteralLoc))
    return;
 
  if (!S.checkSectionName(LiteralLoc, Str))
    return;
 
  SectionAttr *NewAttr = S.mergeSectionAttr(D, AL, Str);
  if (NewAttr) {
    D->addAttr(NewAttr);
    if (isa<FunctionDecl, FunctionTemplateDecl, ObjCMethodDecl,
            ObjCPropertyDecl>(D))
      S.UnifySection(NewAttr->getName(),
                     ASTContext::PSF_Execute | ASTContext::PSF_Read,
                     cast<NamedDecl>(D));
  }
}
 
// This is used for `__declspec(code_seg("segname"))` on a decl.
// `#pragma code_seg("segname")` uses checkSectionName() instead.
static bool checkCodeSegName(Sema &S, SourceLocation LiteralLoc,
                             StringRef CodeSegName) {
  if (llvm::Error E = S.isValidSectionSpecifier(CodeSegName)) {
    S.Diag(LiteralLoc, diag::err_attribute_section_invalid_for_target)
        << toString(std::move(E)) << 0 /*'code-seg'*/;
    return false;
  }
 
  return true;
}
 
CodeSegAttr *Sema::mergeCodeSegAttr(Decl *D, const AttributeCommonInfo &CI,
                                    StringRef Name) {
  // Explicit or partial specializations do not inherit
  // the code_seg attribute from the primary template.
  if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
    if (FD->isFunctionTemplateSpecialization())
      return nullptr;
  }
  if (const auto *ExistingAttr = D->getAttr<CodeSegAttr>()) {
    if (ExistingAttr->getName() == Name)
      return nullptr;
    Diag(ExistingAttr->getLocation(), diag::warn_mismatched_section)
         << 0 /*codeseg*/;
    Diag(CI.getLoc(), diag::note_previous_attribute);
    return nullptr;
  }
  return ::new (Context) CodeSegAttr(Context, CI, Name);
}
 
static void handleCodeSegAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  StringRef Str;
  SourceLocation LiteralLoc;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &LiteralLoc))
    return;
  if (!checkCodeSegName(S, LiteralLoc, Str))
    return;
  if (const auto *ExistingAttr = D->getAttr<CodeSegAttr>()) {
    if (!ExistingAttr->isImplicit()) {
      S.Diag(AL.getLoc(),
             ExistingAttr->getName() == Str
             ? diag::warn_duplicate_codeseg_attribute
             : diag::err_conflicting_codeseg_attribute);
      return;
    }
    D->dropAttr<CodeSegAttr>();
  }
  if (CodeSegAttr *CSA = S.mergeCodeSegAttr(D, AL, Str))
    D->addAttr(CSA);
}
 
// Check for things we'd like to warn about. Multiversioning issues are
// handled later in the process, once we know how many exist.
bool Sema::checkTargetAttr(SourceLocation LiteralLoc, StringRef AttrStr) {
  enum FirstParam { Unsupported, Duplicate, Unknown };
  enum SecondParam { None, CPU, Tune };
  enum ThirdParam { Target, TargetClones };
  if (AttrStr.contains("fpmath="))
    return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
           << Unsupported << None << "fpmath=" << Target;
 
  // Diagnose use of tune if target doesn't support it.
  if (!Context.getTargetInfo().supportsTargetAttributeTune() &&
      AttrStr.contains("tune="))
    return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
           << Unsupported << None << "tune=" << Target;
 
  ParsedTargetAttr ParsedAttrs =
      Context.getTargetInfo().parseTargetAttr(AttrStr);
 
  if (!ParsedAttrs.CPU.empty() &&
      !Context.getTargetInfo().isValidCPUName(ParsedAttrs.CPU))
    return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
           << Unknown << CPU << ParsedAttrs.CPU << Target;
 
  if (!ParsedAttrs.Tune.empty() &&
      !Context.getTargetInfo().isValidCPUName(ParsedAttrs.Tune))
    return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
           << Unknown << Tune << ParsedAttrs.Tune << Target;
 
  if (ParsedAttrs.Duplicate != "")
    return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
           << Duplicate << None << ParsedAttrs.Duplicate << Target;
 
  for (const auto &Feature : ParsedAttrs.Features) {
    auto CurFeature = StringRef(Feature).drop_front(); // remove + or -.
    if (!Context.getTargetInfo().isValidFeatureName(CurFeature))
      return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
             << Unsupported << None << CurFeature << Target;
  }
 
  TargetInfo::BranchProtectionInfo BPI;
  StringRef DiagMsg;
  if (ParsedAttrs.BranchProtection.empty())
    return false;
  if (!Context.getTargetInfo().validateBranchProtection(
          ParsedAttrs.BranchProtection, ParsedAttrs.CPU, BPI, DiagMsg)) {
    if (DiagMsg.empty())
      return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
             << Unsupported << None << "branch-protection" << Target;
    return Diag(LiteralLoc, diag::err_invalid_branch_protection_spec)
           << DiagMsg;
  }
  if (!DiagMsg.empty())
    Diag(LiteralLoc, diag::warn_unsupported_branch_protection_spec) << DiagMsg;
 
  return false;
}
 
// Check Target Version attrs
bool Sema::checkTargetVersionAttr(SourceLocation LiteralLoc, StringRef &AttrStr,
                                  bool &isDefault) {
  enum FirstParam { Unsupported };
  enum SecondParam { None };
  enum ThirdParam { Target, TargetClones, TargetVersion };
  if (AttrStr.trim() == "default")
    isDefault = true;
  llvm::SmallVector<StringRef, 8> Features;
  AttrStr.split(Features, "+");
  for (auto &CurFeature : Features) {
    CurFeature = CurFeature.trim();
    if (CurFeature == "default")
      continue;
    if (!Context.getTargetInfo().validateCpuSupports(CurFeature))
      return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
             << Unsupported << None << CurFeature << TargetVersion;
  }
  return false;
}
 
static void handleTargetVersionAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  StringRef Str;
  SourceLocation LiteralLoc;
  bool isDefault = false;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &LiteralLoc) ||
      S.checkTargetVersionAttr(LiteralLoc, Str, isDefault))
    return;
  // Do not create default only target_version attribute
  if (!isDefault) {
    TargetVersionAttr *NewAttr =
        ::new (S.Context) TargetVersionAttr(S.Context, AL, Str);
    D->addAttr(NewAttr);
  }
}
 
static void handleTargetAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  StringRef Str;
  SourceLocation LiteralLoc;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &LiteralLoc) ||
      S.checkTargetAttr(LiteralLoc, Str))
    return;
 
  TargetAttr *NewAttr = ::new (S.Context) TargetAttr(S.Context, AL, Str);
  D->addAttr(NewAttr);
}
 
bool Sema::checkTargetClonesAttrString(
    SourceLocation LiteralLoc, StringRef Str, const StringLiteral *Literal,
    bool &HasDefault, bool &HasCommas, bool &HasNotDefault,
    SmallVectorImpl<SmallString<64>> &StringsBuffer) {
  enum FirstParam { Unsupported, Duplicate, Unknown };
  enum SecondParam { None, CPU, Tune };
  enum ThirdParam { Target, TargetClones };
  HasCommas = HasCommas || Str.contains(',');
  const TargetInfo &TInfo = Context.getTargetInfo();
  // Warn on empty at the beginning of a string.
  if (Str.size() == 0)
    return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
           << Unsupported << None << "" << TargetClones;
 
  std::pair<StringRef, StringRef> Parts = {{}, Str};
  while (!Parts.second.empty()) {
    Parts = Parts.second.split(',');
    StringRef Cur = Parts.first.trim();
    SourceLocation CurLoc =
        Literal->getLocationOfByte(Cur.data() - Literal->getString().data(),
                                   getSourceManager(), getLangOpts(), TInfo);
 
    bool DefaultIsDupe = false;
    bool HasCodeGenImpact = false;
    if (Cur.empty())
      return Diag(CurLoc, diag::warn_unsupported_target_attribute)
             << Unsupported << None << "" << TargetClones;
 
    if (TInfo.getTriple().isAArch64()) {
      // AArch64 target clones specific
      if (Cur == "default") {
        DefaultIsDupe = HasDefault;
        HasDefault = true;
        if (llvm::is_contained(StringsBuffer, Cur) || DefaultIsDupe)
          Diag(CurLoc, diag::warn_target_clone_duplicate_options);
        else
          StringsBuffer.push_back(Cur);
      } else {
        std::pair<StringRef, StringRef> CurParts = {{}, Cur};
        llvm::SmallVector<StringRef, 8> CurFeatures;
        while (!CurParts.second.empty()) {
          CurParts = CurParts.second.split('+');
          StringRef CurFeature = CurParts.first.trim();
          if (!TInfo.validateCpuSupports(CurFeature)) {
            Diag(CurLoc, diag::warn_unsupported_target_attribute)
                << Unsupported << None << CurFeature << TargetClones;
            continue;
          }
          if (TInfo.doesFeatureAffectCodeGen(CurFeature))
            HasCodeGenImpact = true;
          CurFeatures.push_back(CurFeature);
        }
        // Canonize TargetClones Attributes
        llvm::sort(CurFeatures);
        SmallString<64> Res;
        for (auto &CurFeat : CurFeatures) {
          if (!Res.equals(""))
            Res.append("+");
          Res.append(CurFeat);
        }
        if (llvm::is_contained(StringsBuffer, Res) || DefaultIsDupe)
          Diag(CurLoc, diag::warn_target_clone_duplicate_options);
        else if (!HasCodeGenImpact)
          // Ignore features in target_clone attribute that don't impact
          // code generation
          Diag(CurLoc, diag::warn_target_clone_no_impact_options);
        else if (!Res.empty()) {
          StringsBuffer.push_back(Res);
          HasNotDefault = true;
        }
      }
    } else {
      // Other targets ( currently X86 )
      if (Cur.startswith("arch=")) {
        if (!Context.getTargetInfo().isValidCPUName(
                Cur.drop_front(sizeof("arch=") - 1)))
          return Diag(CurLoc, diag::warn_unsupported_target_attribute)
                 << Unsupported << CPU << Cur.drop_front(sizeof("arch=") - 1)
                 << TargetClones;
      } else if (Cur == "default") {
        DefaultIsDupe = HasDefault;
        HasDefault = true;
      } else if (!Context.getTargetInfo().isValidFeatureName(Cur))
        return Diag(CurLoc, diag::warn_unsupported_target_attribute)
               << Unsupported << None << Cur << TargetClones;
      if (llvm::is_contained(StringsBuffer, Cur) || DefaultIsDupe)
        Diag(CurLoc, diag::warn_target_clone_duplicate_options);
      // Note: Add even if there are duplicates, since it changes name mangling.
      StringsBuffer.push_back(Cur);
    }
  }
  if (Str.rtrim().endswith(","))
    return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
           << Unsupported << None << "" << TargetClones;
  return false;
}
 
static void handleTargetClonesAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (S.Context.getTargetInfo().getTriple().isAArch64() &&
      !S.Context.getTargetInfo().hasFeature("fmv"))
    return;
 
  // Ensure we don't combine these with themselves, since that causes some
  // confusing behavior.
  if (const auto *Other = D->getAttr<TargetClonesAttr>()) {
    S.Diag(AL.getLoc(), diag::err_disallowed_duplicate_attribute) << AL;
    S.Diag(Other->getLocation(), diag::note_conflicting_attribute);
    return;
  }
  if (checkAttrMutualExclusion<TargetClonesAttr>(S, D, AL))
    return;
 
  SmallVector<StringRef, 2> Strings;
  SmallVector<SmallString<64>, 2> StringsBuffer;
  bool HasCommas = false, HasDefault = false, HasNotDefault = false;
 
  for (unsigned I = 0, E = AL.getNumArgs(); I != E; ++I) {
    StringRef CurStr;
    SourceLocation LiteralLoc;
    if (!S.checkStringLiteralArgumentAttr(AL, I, CurStr, &LiteralLoc) ||
        S.checkTargetClonesAttrString(
            LiteralLoc, CurStr,
            cast<StringLiteral>(AL.getArgAsExpr(I)->IgnoreParenCasts()),
            HasDefault, HasCommas, HasNotDefault, StringsBuffer))
      return;
  }
  for (auto &SmallStr : StringsBuffer)
    Strings.push_back(SmallStr.str());
 
  if (HasCommas && AL.getNumArgs() > 1)
    S.Diag(AL.getLoc(), diag::warn_target_clone_mixed_values);
 
  if (S.Context.getTargetInfo().getTriple().isAArch64() && !HasDefault) {
    // Add default attribute if there is no one
    HasDefault = true;
    Strings.push_back("default");
  }
 
  if (!HasDefault) {
    S.Diag(AL.getLoc(), diag::err_target_clone_must_have_default);
    return;
  }
 
  // FIXME: We could probably figure out how to get this to work for lambdas
  // someday.
  if (const auto *MD = dyn_cast<CXXMethodDecl>(D)) {
    if (MD->getParent()->isLambda()) {
      S.Diag(D->getLocation(), diag::err_multiversion_doesnt_support)
          << static_cast<unsigned>(MultiVersionKind::TargetClones)
          << /*Lambda*/ 9;
      return;
    }
  }
 
  // No multiversion if we have default version only.
  if (S.Context.getTargetInfo().getTriple().isAArch64() && !HasNotDefault)
    return;
 
  cast<FunctionDecl>(D)->setIsMultiVersion();
  TargetClonesAttr *NewAttr = ::new (S.Context)
      TargetClonesAttr(S.Context, AL, Strings.data(), Strings.size());
  D->addAttr(NewAttr);
}
 
static void handleMinVectorWidthAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  Expr *E = AL.getArgAsExpr(0);
  uint32_t VecWidth;
  if (!checkUInt32Argument(S, AL, E, VecWidth)) {
    AL.setInvalid();
    return;
  }
 
  MinVectorWidthAttr *Existing = D->getAttr<MinVectorWidthAttr>();
  if (Existing && Existing->getVectorWidth() != VecWidth) {
    S.Diag(AL.getLoc(), diag::warn_duplicate_attribute) << AL;
    return;
  }
 
  D->addAttr(::new (S.Context) MinVectorWidthAttr(S.Context, AL, VecWidth));
}
 
static void handleCleanupAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  Expr *E = AL.getArgAsExpr(0);
  SourceLocation Loc = E->getExprLoc();
  FunctionDecl *FD = nullptr;
  DeclarationNameInfo NI;
 
  // gcc only allows for simple identifiers. Since we support more than gcc, we
  // will warn the user.
  if (auto *DRE = dyn_cast<DeclRefExpr>(E)) {
    if (DRE->hasQualifier())
      S.Diag(Loc, diag::warn_cleanup_ext);
    FD = dyn_cast<FunctionDecl>(DRE->getDecl());
    NI = DRE->getNameInfo();
    if (!FD) {
      S.Diag(Loc, diag::err_attribute_cleanup_arg_not_function) << 1
        << NI.getName();
      return;
    }
  } else if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(E)) {
    if (ULE->hasExplicitTemplateArgs())
      S.Diag(Loc, diag::warn_cleanup_ext);
    FD = S.ResolveSingleFunctionTemplateSpecialization(ULE, true);
    NI = ULE->getNameInfo();
    if (!FD) {
      S.Diag(Loc, diag::err_attribute_cleanup_arg_not_function) << 2
        << NI.getName();
      if (ULE->getType() == S.Context.OverloadTy)
        S.NoteAllOverloadCandidates(ULE);
      return;
    }
  } else {
    S.Diag(Loc, diag::err_attribute_cleanup_arg_not_function) << 0;
    return;
  }
 
  if (FD->getNumParams() != 1) {
    S.Diag(Loc, diag::err_attribute_cleanup_func_must_take_one_arg)
      << NI.getName();
    return;
  }
 
  // We're currently more strict than GCC about what function types we accept.
  // If this ever proves to be a problem it should be easy to fix.
  QualType Ty = S.Context.getPointerType(cast<VarDecl>(D)->getType());
  QualType ParamTy = FD->getParamDecl(0)->getType();
  if (S.CheckAssignmentConstraints(FD->getParamDecl(0)->getLocation(),
                                   ParamTy, Ty) != Sema::Compatible) {
    S.Diag(Loc, diag::err_attribute_cleanup_func_arg_incompatible_type)
      << NI.getName() << ParamTy << Ty;
    return;
  }
 
  D->addAttr(::new (S.Context) CleanupAttr(S.Context, AL, FD));
}
 
static void handleEnumExtensibilityAttr(Sema &S, Decl *D,
                                        const ParsedAttr &AL) {
  if (!AL.isArgIdent(0)) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
        << AL << 0 << AANT_ArgumentIdentifier;
    return;
  }
 
  EnumExtensibilityAttr::Kind ExtensibilityKind;
  IdentifierInfo *II = AL.getArgAsIdent(0)->Ident;
  if (!EnumExtensibilityAttr::ConvertStrToKind(II->getName(),
                                               ExtensibilityKind)) {
    S.Diag(AL.getLoc(), diag::warn_attribute_type_not_supported) << AL << II;
    return;
  }
 
  D->addAttr(::new (S.Context)
                 EnumExtensibilityAttr(S.Context, AL, ExtensibilityKind));
}
 
/// Handle __attribute__((format_arg((idx)))) attribute based on
/// http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
static void handleFormatArgAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  Expr *IdxExpr = AL.getArgAsExpr(0);
  ParamIdx Idx;
  if (!checkFunctionOrMethodParameterIndex(S, D, AL, 1, IdxExpr, Idx))
    return;
 
  // Make sure the format string is really a string.
  QualType Ty = getFunctionOrMethodParamType(D, Idx.getASTIndex());
 
  bool NotNSStringTy = !isNSStringType(Ty, S.Context);
  if (NotNSStringTy &&
      !isCFStringType(Ty, S.Context) &&
      (!Ty->isPointerType() ||
       !Ty->castAs<PointerType>()->getPointeeType()->isCharType())) {
    S.Diag(AL.getLoc(), diag::err_format_attribute_not)
        << IdxExpr->getSourceRange() << getFunctionOrMethodParamRange(D, 0);
    return;
  }
  Ty = getFunctionOrMethodResultType(D);
  // replace instancetype with the class type
  auto Instancetype = S.Context.getObjCInstanceTypeDecl()->getTypeForDecl();
  if (Ty->getAs<TypedefType>() == Instancetype)
    if (auto *OMD = dyn_cast<ObjCMethodDecl>(D))
      if (auto *Interface = OMD->getClassInterface())
        Ty = S.Context.getObjCObjectPointerType(
            QualType(Interface->getTypeForDecl(), 0));
  if (!isNSStringType(Ty, S.Context, /*AllowNSAttributedString=*/true) &&
      !isCFStringType(Ty, S.Context) &&
      (!Ty->isPointerType() ||
       !Ty->castAs<PointerType>()->getPointeeType()->isCharType())) {
    S.Diag(AL.getLoc(), diag::err_format_attribute_result_not)
        << (NotNSStringTy ? "string type" : "NSString")
        << IdxExpr->getSourceRange() << getFunctionOrMethodParamRange(D, 0);
    return;
  }
 
  D->addAttr(::new (S.Context) FormatArgAttr(S.Context, AL, Idx));
}
 
enum FormatAttrKind {
  CFStringFormat,
  NSStringFormat,
  StrftimeFormat,
  SupportedFormat,
  IgnoredFormat,
  InvalidFormat
};
 
/// getFormatAttrKind - Map from format attribute names to supported format
/// types.
static FormatAttrKind getFormatAttrKind(StringRef Format) {
  return llvm::StringSwitch<FormatAttrKind>(Format)
      // Check for formats that get handled specially.
      .Case("NSString", NSStringFormat)
      .Case("CFString", CFStringFormat)
      .Case("strftime", StrftimeFormat)
 
      // Otherwise, check for supported formats.
      .Cases("scanf", "printf", "printf0", "strfmon", SupportedFormat)
      .Cases("cmn_err", "vcmn_err", "zcmn_err", SupportedFormat)
      .Case("kprintf", SupportedFormat)         // OpenBSD.
      .Case("freebsd_kprintf", SupportedFormat) // FreeBSD.
      .Case("os_trace", SupportedFormat)
      .Case("os_log", SupportedFormat)
 
      .Cases("gcc_diag", "gcc_cdiag", "gcc_cxxdiag", "gcc_tdiag", IgnoredFormat)
      .Default(InvalidFormat);
}
 
/// Handle __attribute__((init_priority(priority))) attributes based on
/// http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Attributes.html
static void handleInitPriorityAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!S.getLangOpts().CPlusPlus) {
    S.Diag(AL.getLoc(), diag::warn_attribute_ignored) << AL;
    return;
  }
  
  if (S.getLangOpts().HLSL) {
    S.Diag(AL.getLoc(), diag::err_hlsl_init_priority_unsupported);
    return;
  }
 
  if (S.getCurFunctionOrMethodDecl()) {
    S.Diag(AL.getLoc(), diag::err_init_priority_object_attr);
    AL.setInvalid();
    return;
  }
  QualType T = cast<VarDecl>(D)->getType();
  if (S.Context.getAsArrayType(T))
    T = S.Context.getBaseElementType(T);
  if (!T->getAs<RecordType>()) {
    S.Diag(AL.getLoc(), diag::err_init_priority_object_attr);
    AL.setInvalid();
    return;
  }
 
  Expr *E = AL.getArgAsExpr(0);
  uint32_t prioritynum;
  if (!checkUInt32Argument(S, AL, E, prioritynum)) {
    AL.setInvalid();
    return;
  }
 
  // Only perform the priority check if the attribute is outside of a system
  // header. Values <= 100 are reserved for the implementation, and libc++
  // benefits from being able to specify values in that range.
  if ((prioritynum < 101 || prioritynum > 65535) &&
      !S.getSourceManager().isInSystemHeader(AL.getLoc())) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_out_of_range)
        << E->getSourceRange() << AL << 101 << 65535;
    AL.setInvalid();
    return;
  }
  D->addAttr(::new (S.Context) InitPriorityAttr(S.Context, AL, prioritynum));
}
 
ErrorAttr *Sema::mergeErrorAttr(Decl *D, const AttributeCommonInfo &CI,
                                StringRef NewUserDiagnostic) {
  if (const auto *EA = D->getAttr<ErrorAttr>()) {
    std::string NewAttr = CI.getNormalizedFullName();
    assert((NewAttr == "error" || NewAttr == "warning") &&
           "unexpected normalized full name");
    bool Match = (EA->isError() && NewAttr == "error") ||
                 (EA->isWarning() && NewAttr == "warning");
    if (!Match) {
      Diag(EA->getLocation(), diag::err_attributes_are_not_compatible)
          << CI << EA;
      Diag(CI.getLoc(), diag::note_conflicting_attribute);
      return nullptr;
    }
    if (EA->getUserDiagnostic() != NewUserDiagnostic) {
      Diag(CI.getLoc(), diag::warn_duplicate_attribute) << EA;
      Diag(EA->getLoc(), diag::note_previous_attribute);
    }
    D->dropAttr<ErrorAttr>();
  }
  return ::new (Context) ErrorAttr(Context, CI, NewUserDiagnostic);
}
 
FormatAttr *Sema::mergeFormatAttr(Decl *D, const AttributeCommonInfo &CI,
                                  IdentifierInfo *Format, int FormatIdx,
                                  int FirstArg) {
  // Check whether we already have an equivalent format attribute.
  for (auto *F : D->specific_attrs<FormatAttr>()) {
    if (F->getType() == Format &&
        F->getFormatIdx() == FormatIdx &&
        F->getFirstArg() == FirstArg) {
      // If we don't have a valid location for this attribute, adopt the
      // location.
      if (F->getLocation().isInvalid())
        F->setRange(CI.getRange());
      return nullptr;
    }
  }
 
  return ::new (Context) FormatAttr(Context, CI, Format, FormatIdx, FirstArg);
}
 
/// Handle __attribute__((format(type,idx,firstarg))) attributes based on
/// http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
static void handleFormatAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (!AL.isArgIdent(0)) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_n_type)
        << AL << 1 << AANT_ArgumentIdentifier;
    return;
  }
 
  // In C++ the implicit 'this' function parameter also counts, and they are
  // counted from one.
  bool HasImplicitThisParam = isInstanceMethod(D);
  unsigned NumArgs = getFunctionOrMethodNumParams(D) + HasImplicitThisParam;
 
  IdentifierInfo *II = AL.getArgAsIdent(0)->Ident;
  StringRef Format = II->getName();
 
  if (normalizeName(Format)) {
    // If we've modified the string name, we need a new identifier for it.
    II = &S.Context.Idents.get(Format);
  }
 
  // Check for supported formats.
  FormatAttrKind Kind = getFormatAttrKind(Format);
 
  if (Kind == IgnoredFormat)
    return;
 
  if (Kind == InvalidFormat) {
    S.Diag(AL.getLoc(), diag::warn_attribute_type_not_supported)
        << AL << II->getName();
    return;
  }
 
  // checks for the 2nd argument
  Expr *IdxExpr = AL.getArgAsExpr(1);
  uint32_t Idx;
  if (!checkUInt32Argument(S, AL, IdxExpr, Idx, 2))
    return;
 
  if (Idx < 1 || Idx > NumArgs) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_out_of_bounds)
        << AL << 2 << IdxExpr->getSourceRange();
    return;
  }
 
  // FIXME: Do we need to bounds check?
  unsigned ArgIdx = Idx - 1;
 
  if (HasImplicitThisParam) {
    if (ArgIdx == 0) {
      S.Diag(AL.getLoc(),
             diag::err_format_attribute_implicit_this_format_string)
        << IdxExpr->getSourceRange();
      return;
    }
    ArgIdx--;
  }
 
  // make sure the format string is really a string
  QualType Ty = getFunctionOrMethodParamType(D, ArgIdx);
 
  if (!isNSStringType(Ty, S.Context, true) &&
      !isCFStringType(Ty, S.Context) &&
      (!Ty->isPointerType() ||
       !Ty->castAs<PointerType>()->getPointeeType()->isCharType())) {
    S.Diag(AL.getLoc(), diag::err_format_attribute_not)
      << IdxExpr->getSourceRange() << getFunctionOrMethodParamRange(D, ArgIdx);
    return;
  }
 
  // check the 3rd argument
  Expr *FirstArgExpr = AL.getArgAsExpr(2);
  uint32_t FirstArg;
  if (!checkUInt32Argument(S, AL, FirstArgExpr, FirstArg, 3))
    return;
 
  // FirstArg == 0 is is always valid.
  if (FirstArg != 0) {
    if (Kind == StrftimeFormat) {
      // If the kind is strftime, FirstArg must be 0 because strftime does not
      // use any variadic arguments.
      S.Diag(AL.getLoc(), diag::err_format_strftime_third_parameter)
          << FirstArgExpr->getSourceRange()
          << FixItHint::CreateReplacement(FirstArgExpr->getSourceRange(), "0");
      return;
    } else if (isFunctionOrMethodVariadic(D)) {
      // Else, if the function is variadic, then FirstArg must be 0 or the
      // "position" of the ... parameter. It's unusual to use 0 with variadic
      // functions, so the fixit proposes the latter.
      if (FirstArg != NumArgs + 1) {
        S.Diag(AL.getLoc(), diag::err_attribute_argument_out_of_bounds)
            << AL << 3 << FirstArgExpr->getSourceRange()
            << FixItHint::CreateReplacement(FirstArgExpr->getSourceRange(),
                                            std::to_string(NumArgs + 1));
        return;
      }
    } else {
      // Inescapable GCC compatibility diagnostic.
      S.Diag(D->getLocation(), diag::warn_gcc_requires_variadic_function) << AL;
      if (FirstArg <= Idx) {
        // Else, the function is not variadic, and FirstArg must be 0 or any
        // parameter after the format parameter. We don't offer a fixit because
        // there are too many possible good values.
        S.Diag(AL.getLoc(), diag::err_attribute_argument_out_of_bounds)
            << AL << 3 << FirstArgExpr->getSourceRange();
        return;
      }
    }
  }
 
  FormatAttr *NewAttr = S.mergeFormatAttr(D, AL, II, Idx, FirstArg);
  if (NewAttr)
    D->addAttr(NewAttr);
}
 
/// Handle __attribute__((callback(CalleeIdx, PayloadIdx0, ...))) attributes.
static void handleCallbackAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // The index that identifies the callback callee is mandatory.
  if (AL.getNumArgs() == 0) {
    S.Diag(AL.getLoc(), diag::err_callback_attribute_no_callee)
        << AL.getRange();
    return;
  }
 
  bool HasImplicitThisParam = isInstanceMethod(D);
  int32_t NumArgs = getFunctionOrMethodNumParams(D);
 
  FunctionDecl *FD = D->getAsFunction();
  assert(FD && "Expected a function declaration!");
 
  llvm::StringMap<int> NameIdxMapping;
  NameIdxMapping["__"] = -1;
 
  NameIdxMapping["this"] = 0;
 
  int Idx = 1;
  for (const ParmVarDecl *PVD : FD->parameters())
    NameIdxMapping[PVD->getName()] = Idx++;
 
  auto UnknownName = NameIdxMapping.end();
 
  SmallVector<int, 8> EncodingIndices;
  for (unsigned I = 0, E = AL.getNumArgs(); I < E; ++I) {
    SourceRange SR;
    int32_t ArgIdx;
 
    if (AL.isArgIdent(I)) {
      IdentifierLoc *IdLoc = AL.getArgAsIdent(I);
      auto It = NameIdxMapping.find(IdLoc->Ident->getName());
      if (It == UnknownName) {
        S.Diag(AL.getLoc(), diag::err_callback_attribute_argument_unknown)
            << IdLoc->Ident << IdLoc->Loc;
        return;
      }
 
      SR = SourceRange(IdLoc->Loc);
      ArgIdx = It->second;
    } else if (AL.isArgExpr(I)) {
      Expr *IdxExpr = AL.getArgAsExpr(I);
 
      // If the expression is not parseable as an int32_t we have a problem.
      if (!checkUInt32Argument(S, AL, IdxExpr, (uint32_t &)ArgIdx, I + 1,
                               false)) {
        S.Diag(AL.getLoc(), diag::err_attribute_argument_out_of_bounds)
            << AL << (I + 1) << IdxExpr->getSourceRange();
        return;
      }
 
      // Check oob, excluding the special values, 0 and -1.
      if (ArgIdx < -1 || ArgIdx > NumArgs) {
        S.Diag(AL.getLoc(), diag::err_attribute_argument_out_of_bounds)
            << AL << (I + 1) << IdxExpr->getSourceRange();
        return;
      }
 
      SR = IdxExpr->getSourceRange();
    } else {
      llvm_unreachable("Unexpected ParsedAttr argument type!");
    }
 
    if (ArgIdx == 0 && !HasImplicitThisParam) {
      S.Diag(AL.getLoc(), diag::err_callback_implicit_this_not_available)
          << (I + 1) << SR;
      return;
    }
 
    // Adjust for the case we do not have an implicit "this" parameter. In this
    // case we decrease all positive values by 1 to get LLVM argument indices.
    if (!HasImplicitThisParam && ArgIdx > 0)
      ArgIdx -= 1;
 
    EncodingIndices.push_back(ArgIdx);
  }
 
  int CalleeIdx = EncodingIndices.front();
  // Check if the callee index is proper, thus not "this" and not "unknown".
  // This means the "CalleeIdx" has to be non-negative if "HasImplicitThisParam"
  // is false and positive if "HasImplicitThisParam" is true.
  if (CalleeIdx < (int)HasImplicitThisParam) {
    S.Diag(AL.getLoc(), diag::err_callback_attribute_invalid_callee)
        << AL.getRange();
    return;
  }
 
  // Get the callee type, note the index adjustment as the AST doesn't contain
  // the this type (which the callee cannot reference anyway!).
  const Type *CalleeType =
      getFunctionOrMethodParamType(D, CalleeIdx - HasImplicitThisParam)
          .getTypePtr();
  if (!CalleeType || !CalleeType->isFunctionPointerType()) {
    S.Diag(AL.getLoc(), diag::err_callback_callee_no_function_type)
        << AL.getRange();
    return;
  }
 
  const Type *CalleeFnType =
      CalleeType->getPointeeType()->getUnqualifiedDesugaredType();
 
  // TODO: Check the type of the callee arguments.
 
  const auto *CalleeFnProtoType = dyn_cast<FunctionProtoType>(CalleeFnType);
  if (!CalleeFnProtoType) {
    S.Diag(AL.getLoc(), diag::err_callback_callee_no_function_type)
        << AL.getRange();
    return;
  }
 
  if (CalleeFnProtoType->getNumParams() > EncodingIndices.size() - 1) {
    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments)
        << AL << (unsigned)(EncodingIndices.size() - 1);
    return;
  }
 
  if (CalleeFnProtoType->getNumParams() < EncodingIndices.size() - 1) {
    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments)
        << AL << (unsigned)(EncodingIndices.size() - 1);
    return;
  }
 
  if (CalleeFnProtoType->isVariadic()) {
    S.Diag(AL.getLoc(), diag::err_callback_callee_is_variadic) << AL.getRange();
    return;
  }
 
  // Do not allow multiple callback attributes.
  if (D->hasAttr<CallbackAttr>()) {
    S.Diag(AL.getLoc(), diag::err_callback_attribute_multiple) << AL.getRange();
    return;
  }
 
  D->addAttr(::new (S.Context) CallbackAttr(
      S.Context, AL, EncodingIndices.data(), EncodingIndices.size()));
}
 
static bool isFunctionLike(const Type &T) {
  // Check for explicit function types.
  // 'called_once' is only supported in Objective-C and it has
  // function pointers and block pointers.
  return T.isFunctionPointerType() || T.isBlockPointerType();
}
 
/// Handle 'called_once' attribute.
static void handleCalledOnceAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // 'called_once' only applies to parameters representing functions.
  QualType T = cast<ParmVarDecl>(D)->getType();
 
  if (!isFunctionLike(*T)) {
    S.Diag(AL.getLoc(), diag::err_called_once_attribute_wrong_type);
    return;
  }
 
  D->addAttr(::new (S.Context) CalledOnceAttr(S.Context, AL));
}
 
static void handleTransparentUnionAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Try to find the underlying union declaration.
  RecordDecl *RD = nullptr;
  const auto *TD = dyn_cast<TypedefNameDecl>(D);
  if (TD && TD->getUnderlyingType()->isUnionType())
    RD = TD->getUnderlyingType()->getAsUnionType()->getDecl();
  else
    RD = dyn_cast<RecordDecl>(D);
 
  if (!RD || !RD->isUnion()) {
    S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type) << AL
                                                              << ExpectedUnion;
    return;
  }
 
  if (!RD->isCompleteDefinition()) {
    if (!RD->isBeingDefined())
      S.Diag(AL.getLoc(),
             diag::warn_transparent_union_attribute_not_definition);
    return;
  }
 
  RecordDecl::field_iterator Field = RD->field_begin(),
                          FieldEnd = RD->field_end();
  if (Field == FieldEnd) {
    S.Diag(AL.getLoc(), diag::warn_transparent_union_attribute_zero_fields);
    return;
  }
 
  FieldDecl *FirstField = *Field;
  QualType FirstType = FirstField->getType();
  if (FirstType->hasFloatingRepresentation() || FirstType->isVectorType()) {
    S.Diag(FirstField->getLocation(),
           diag::warn_transparent_union_attribute_floating)
      << FirstType->isVectorType() << FirstType;
    return;
  }
 
  if (FirstType->isIncompleteType())
    return;
  uint64_t FirstSize = S.Context.getTypeSize(FirstType);
  uint64_t FirstAlign = S.Context.getTypeAlign(FirstType);
  for (; Field != FieldEnd; ++Field) {
    QualType FieldType = Field->getType();
    if (FieldType->isIncompleteType())
      return;
    // FIXME: this isn't fully correct; we also need to test whether the
    // members of the union would all have the same calling convention as the
    // first member of the union. Checking just the size and alignment isn't
    // sufficient (consider structs passed on the stack instead of in registers
    // as an example).
    if (S.Context.getTypeSize(FieldType) != FirstSize ||
        S.Context.getTypeAlign(FieldType) > FirstAlign) {
      // Warn if we drop the attribute.
      bool isSize = S.Context.getTypeSize(FieldType) != FirstSize;
      unsigned FieldBits = isSize ? S.Context.getTypeSize(FieldType)
                                  : S.Context.getTypeAlign(FieldType);
      S.Diag(Field->getLocation(),
             diag::warn_transparent_union_attribute_field_size_align)
          << isSize << *Field << FieldBits;
      unsigned FirstBits = isSize ? FirstSize : FirstAlign;
      S.Diag(FirstField->getLocation(),
             diag::note_transparent_union_first_field_size_align)
          << isSize << FirstBits;
      return;
    }
  }
 
  RD->addAttr(::new (S.Context) TransparentUnionAttr(S.Context, AL));
}
 
void Sema::AddAnnotationAttr(Decl *D, const AttributeCommonInfo &CI,
                             StringRef Str, MutableArrayRef<Expr *> Args) {
  auto *Attr = AnnotateAttr::Create(Context, Str, Args.data(), Args.size(), CI);
  if (ConstantFoldAttrArgs(
          CI, MutableArrayRef<Expr *>(Attr->args_begin(), Attr->args_end()))) {
    D->addAttr(Attr);
  }
}
 
static void handleAnnotateAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // Make sure that there is a string literal as the annotation's first
  // argument.
  StringRef Str;
  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str))
    return;
 
  llvm::SmallVector<Expr *, 4> Args;
  Args.reserve(AL.getNumArgs() - 1);
  for (unsigned Idx = 1; Idx < AL.getNumArgs(); Idx++) {
    assert(!AL.isArgIdent(Idx));
    Args.push_back(AL.getArgAsExpr(Idx));
  }
 
  S.AddAnnotationAttr(D, AL, Str, Args);
}
 
static void handleAlignValueAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  S.AddAlignValueAttr(D, AL, AL.getArgAsExpr(0));
}
 
void Sema::AddAlignValueAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E) {
  AlignValueAttr TmpAttr(Context, CI, E);
  SourceLocation AttrLoc = CI.getLoc();
 
  QualType T;
  if (const auto *TD = dyn_cast<TypedefNameDecl>(D))
    T = TD->getUnderlyingType();
  else if (const auto *VD = dyn_cast<ValueDecl>(D))
    T = VD->getType();
  else
    llvm_unreachable("Unknown decl type for align_value");
 
  if (!T->isDependentType() && !T->isAnyPointerType() &&
      !T->isReferenceType() && !T->isMemberPointerType()) {
    Diag(AttrLoc, diag::warn_attribute_pointer_or_reference_only)
      << &TmpAttr << T << D->getSourceRange();
    return;
  }
 
  if (!E->isValueDependent()) {
    llvm::APSInt Alignment;
    ExprResult ICE = VerifyIntegerConstantExpression(
        E, &Alignment, diag::err_align_value_attribute_argument_not_int);
    if (ICE.isInvalid())
      return;
 
    if (!Alignment.isPowerOf2()) {
      Diag(AttrLoc, diag::err_alignment_not_power_of_two)
        << E->getSourceRange();
      return;
    }
 
    D->addAttr(::new (Context) AlignValueAttr(Context, CI, ICE.get()));
    return;
  }
 
  // Save dependent expressions in the AST to be instantiated.
  D->addAttr(::new (Context) AlignValueAttr(Context, CI, E));
}
 
static void handleAlignedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // check the attribute arguments.
  if (AL.getNumArgs() > 1) {
    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 1;
    return;
  }
 
  if (AL.getNumArgs() == 0) {
    D->addAttr(::new (S.Context) AlignedAttr(S.Context, AL, true, nullptr));
    return;
  }
 
  Expr *E = AL.getArgAsExpr(0);
  if (AL.isPackExpansion() && !E->containsUnexpandedParameterPack()) {
    S.Diag(AL.getEllipsisLoc(),
           diag::err_pack_expansion_without_parameter_packs);
    return;
  }
 
  if (!AL.isPackExpansion() && S.DiagnoseUnexpandedParameterPack(E))
    return;
 
  S.AddAlignedAttr(D, AL, E, AL.isPackExpansion());
}
 
void Sema::AddAlignedAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E,
                          bool IsPackExpansion) {
  AlignedAttr TmpAttr(Context, CI, true, E);
  SourceLocation AttrLoc = CI.getLoc();
 
  // C++11 alignas(...) and C11 _Alignas(...) have additional requirements.
  if (TmpAttr.isAlignas()) {
    // C++11 [dcl.align]p1:
    //   An alignment-specifier may be applied to a variable or to a class
    //   data member, but it shall not be applied to a bit-field, a function
    //   parameter, the formal parameter of a catch clause, or a variable
    //   declared with the register storage class specifier. An
    //   alignment-specifier may also be applied to the declaration of a class
    //   or enumeration type.
    // CWG 2354:
    //   CWG agreed to remove permission for alignas to be applied to
    //   enumerations.
    // C11 6.7.5/2:
    //   An alignment attribute shall not be specified in a declaration of
    //   a typedef, or a bit-field, or a function, or a parameter, or an
    //   object declared with the register storage-class specifier.
    int DiagKind = -1;
    if (isa<ParmVarDecl>(D)) {
      DiagKind = 0;
    } else if (const auto *VD = dyn_cast<VarDecl>(D)) {
      if (VD->getStorageClass() == SC_Register)
        DiagKind = 1;
      if (VD->isExceptionVariable())
        DiagKind = 2;
    } else if (const auto *FD = dyn_cast<FieldDecl>(D)) {
      if (FD->isBitField())
        DiagKind = 3;
    } else if (const auto *ED = dyn_cast<EnumDecl>(D)) {
      if (ED->getLangOpts().CPlusPlus)
        DiagKind = 4;
    } else if (!isa<TagDecl>(D)) {
      Diag(AttrLoc, diag::err_attribute_wrong_decl_type) << &TmpAttr
        << (TmpAttr.isC11() ? ExpectedVariableOrField
                            : ExpectedVariableFieldOrTag);
      return;
    }
    if (DiagKind != -1) {
      Diag(AttrLoc, diag::err_alignas_attribute_wrong_decl_type)
        << &TmpAttr << DiagKind;
      return;
    }
  }
 
  if (E->isValueDependent()) {
    // We can't support a dependent alignment on a non-dependent type,
    // because we have no way to model that a type is "alignment-dependent"
    // but not dependent in any other way.
    if (const auto *TND = dyn_cast<TypedefNameDecl>(D)) {
      if (!TND->getUnderlyingType()->isDependentType()) {
        Diag(AttrLoc, diag::err_alignment_dependent_typedef_name)
            << E->getSourceRange();
        return;
      }
    }
 
    // Save dependent expressions in the AST to be instantiated.
    AlignedAttr *AA = ::new (Context) AlignedAttr(Context, CI, true, E);
    AA->setPackExpansion(IsPackExpansion);
    D->addAttr(AA);
    return;
  }
 
  // FIXME: Cache the number on the AL object?
  llvm::APSInt Alignment;
  ExprResult ICE = VerifyIntegerConstantExpression(
      E, &Alignment, diag::err_aligned_attribute_argument_not_int);
  if (ICE.isInvalid())
    return;
 
  uint64_t AlignVal = Alignment.getZExtValue();
  // C++11 [dcl.align]p2:
  //   -- if the constant expression evaluates to zero, the alignment
  //      specifier shall have no effect
  // C11 6.7.5p6:
  //   An alignment specification of zero has no effect.
  if (!(TmpAttr.isAlignas() && !Alignment)) {
    if (!llvm::isPowerOf2_64(AlignVal)) {
      Diag(AttrLoc, diag::err_alignment_not_power_of_two)
        << E->getSourceRange();
      return;
    }
  }
 
  uint64_t MaximumAlignment = Sema::MaximumAlignment;
  if (Context.getTargetInfo().getTriple().isOSBinFormatCOFF())
    MaximumAlignment = std::min(MaximumAlignment, uint64_t(8192));
  if (AlignVal > MaximumAlignment) {
    Diag(AttrLoc, diag::err_attribute_aligned_too_great)
        << MaximumAlignment << E->getSourceRange();
    return;
  }
 
  const auto *VD = dyn_cast<VarDecl>(D);
  if (VD) {
    unsigned MaxTLSAlign =
        Context.toCharUnitsFromBits(Context.getTargetInfo().getMaxTLSAlign())
            .getQuantity();
    if (MaxTLSAlign && AlignVal > MaxTLSAlign &&
        VD->getTLSKind() != VarDecl::TLS_None) {
      Diag(VD->getLocation(), diag::err_tls_var_aligned_over_maximum)
          << (unsigned)AlignVal << VD << MaxTLSAlign;
      return;
    }
  }
 
  // On AIX, an aligned attribute can not decrease the alignment when applied
  // to a variable declaration with vector type.
  if (VD && Context.getTargetInfo().getTriple().isOSAIX()) {
    const Type *Ty = VD->getType().getTypePtr();
    if (Ty->isVectorType() && AlignVal < 16) {
      Diag(VD->getLocation(), diag::warn_aligned_attr_underaligned)
          << VD->getType() << 16;
      return;
    }
  }
 
  AlignedAttr *AA = ::new (Context) AlignedAttr(Context, CI, true, ICE.get());
  AA->setPackExpansion(IsPackExpansion);
  D->addAttr(AA);
}
 
void Sema::AddAlignedAttr(Decl *D, const AttributeCommonInfo &CI,
                          TypeSourceInfo *TS, bool IsPackExpansion) {
  // FIXME: Cache the number on the AL object if non-dependent?
  // FIXME: Perform checking of type validity
  AlignedAttr *AA = ::new (Context) AlignedAttr(Context, CI, false, TS);
  AA->setPackExpansion(IsPackExpansion);
  D->addAttr(AA);
}
 
void Sema::CheckAlignasUnderalignment(Decl *D) {
  assert(D->hasAttrs() && "no attributes on decl");
 
  QualType UnderlyingTy, DiagTy;
  if (const auto *VD = dyn_cast<ValueDecl>(D)) {
    UnderlyingTy = DiagTy = VD->getType();
  } else {
    UnderlyingTy = DiagTy = Context.getTagDeclType(cast<TagDecl>(D));
    if (const auto *ED = dyn_cast<EnumDecl>(D))
      UnderlyingTy = ED->getIntegerType();
  }
  if (DiagTy->isDependentType() || DiagTy->isIncompleteType())
    return;
 
  // C++11 [dcl.align]p5, C11 6.7.5/4:
  //   The combined effect of all alignment attributes in a declaration shall
  //   not specify an alignment that is less strict than the alignment that
  //   would otherwise be required for the entity being declared.
  AlignedAttr *AlignasAttr = nullptr;
  AlignedAttr *LastAlignedAttr = nullptr;
  unsigned Align = 0;
  for (auto *I : D->specific_attrs<AlignedAttr>()) {
    if (I->isAlignmentDependent())
      return;
    if (I->isAlignas())
      AlignasAttr = I;
    Align = std::max(Align, I->getAlignment(Context));
    LastAlignedAttr = I;
  }
 
  if (Align && DiagTy->isSizelessType()) {
    Diag(LastAlignedAttr->getLocation(), diag::err_attribute_sizeless_type)
        << LastAlignedAttr << DiagTy;
  } else if (AlignasAttr && Align) {
    CharUnits RequestedAlign = Context.toCharUnitsFromBits(Align);
    CharUnits NaturalAlign = Context.getTypeAlignInChars(UnderlyingTy);
    if (NaturalAlign > RequestedAlign)
      Diag(AlignasAttr->getLocation(), diag::err_alignas_underaligned)
        << DiagTy << (unsigned)NaturalAlign.getQuantity();
  }
}
 
bool Sema::checkMSInheritanceAttrOnDefinition(
    CXXRecordDecl *RD, SourceRange Range, bool BestCase,
    MSInheritanceModel ExplicitModel) {
  assert(RD->hasDefinition() && "RD has no definition!");
 
  // We may not have seen base specifiers or any virtual methods yet.  We will
  // have to wait until the record is defined to catch any mismatches.
  if (!RD->getDefinition()->isCompleteDefinition())
    return false;
 
  // The unspecified model never matches what a definition could need.
  if (ExplicitModel == MSInheritanceModel::Unspecified)
    return false;
 
  if (BestCase) {
    if (RD->calculateInheritanceModel() == ExplicitModel)
      return false;
  } else {
    if (RD->calculateInheritanceModel() <= ExplicitModel)
      return false;
  }
 
  Diag(Range.getBegin(), diag::err_mismatched_ms_inheritance)
      << 0 /*definition*/;
  Diag(RD->getDefinition()->getLocation(), diag::note_defined_here) << RD;
  return true;
}
 
/// parseModeAttrArg - Parses attribute mode string and returns parsed type
/// attribute.
static void parseModeAttrArg(Sema &S, StringRef Str, unsigned &DestWidth,
                             bool &IntegerMode, bool &ComplexMode,
                             FloatModeKind &ExplicitType) {
  IntegerMode = true;
  ComplexMode = false;
  ExplicitType = FloatModeKind::NoFloat;
  switch (Str.size()) {
  case 2:
    switch (Str[0]) {
    case 'Q':
      DestWidth = 8;
      break;
    case 'H':
      DestWidth = 16;
      break;
    case 'S':
      DestWidth = 32;
      break;
    case 'D':
      DestWidth = 64;
      break;
    case 'X':
      DestWidth = 96;
      break;
    case 'K': // KFmode - IEEE quad precision (__float128)
      ExplicitType = FloatModeKind::Float128;
      DestWidth = Str[1] == 'I' ? 0 : 128;
      break;
    case 'T':
      ExplicitType = FloatModeKind::LongDouble;
      DestWidth = 128;
      break;
    case 'I':
      ExplicitType = FloatModeKind::Ibm128;
      DestWidth = Str[1] == 'I' ? 0 : 128;
      break;
    }
    if (Str[1] == 'F') {
      IntegerMode = false;
    } else if (Str[1] == 'C') {
      IntegerMode = false;
      ComplexMode = true;
    } else if (Str[1] != 'I') {
      DestWidth = 0;
    }
    break;
  case 4:
    // FIXME: glibc uses 'word' to define register_t; this is narrower than a
    // pointer on PIC16 and other embedded platforms.
    if (Str == "word")
      DestWidth = S.Context.getTargetInfo().getRegisterWidth();
    else if (Str == "byte")
      DestWidth = S.Context.getTargetInfo().getCharWidth();
    break;
  case 7:
    if (Str == "pointer")
      DestWidth = S.Context.getTargetInfo().getPointerWidth(LangAS::Default);
    break;
  case 11:
    if (Str == "unwind_word")
      DestWidth = S.Context.getTargetInfo().getUnwindWordWidth();
    break;
  }
}
 
/// handleModeAttr - This attribute modifies the width of a decl with primitive
/// type.
///
/// Despite what would be logical, the mode attribute is a decl attribute, not a
/// type attribute: 'int ** __attribute((mode(HI))) *G;' tries to make 'G' be
/// HImode, not an intermediate pointer.
static void handleModeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  // This attribute isn't documented, but glibc uses it.  It changes
  // the width of an int or unsigned int to the specified size.
  if (!AL.isArgIdent(0)) {
    S.Diag(AL.getLoc(), diag::err_attribute_argument_type)
        << AL << AANT_ArgumentIdentifier;
    return;
  }
 
  IdentifierInfo *Name = AL.getArgAsIdent(0)->Ident;
 
  S.AddModeAttr(D, AL, Name);
}
 
void Sema::AddModeAttr(Decl *D, const AttributeCommonInfo &CI,
                       IdentifierInfo *Name, bool InInstantiation) {
  StringRef Str = Name->getName();
  normalizeName(Str);
  SourceLocation AttrLoc = CI.getLoc();
 
  unsigned DestWidth = 0;
  bool IntegerMode = true;
  bool ComplexMode = false;
  FloatModeKind ExplicitType = FloatModeKind::NoFloat;
  llvm::APInt VectorSize(64, 0);
  if (Str.size() >= 4 && Str[0] == 'V') {
    // Minimal length of vector mode is 4: 'V' + NUMBER(>=1) + TYPE(>=2).
    size_t StrSize = Str.size();
    size_t VectorStringLength = 0;
    while ((VectorStringLength + 1) < StrSize &&
           isdigit(Str[VectorStringLength + 1]))
      ++VectorStringLength;
    if (VectorStringLength &&
        !Str.substr(1, VectorStringLength).getAsInteger(10, VectorSize) &&
        VectorSize.isPowerOf2()) {
      parseModeAttrArg(*this, Str.substr(VectorStringLength + 1), DestWidth,
                       IntegerMode, ComplexMode, ExplicitType);
      // Avoid duplicate warning from template instantiation.
      if (!InInstantiation)
        Diag(AttrLoc, diag::warn_vector_mode_deprecated);
    } else {
      VectorSize = 0;
    }
  }
 
  if (!VectorSize)
    parseModeAttrArg(*this, Str, DestWidth, IntegerMode, ComplexMode,
                     ExplicitType);
 
  // FIXME: Sync this with InitializePredefinedMacros; we need to match int8_t
  // and friends, at least with glibc.
  // FIXME: Make sure floating-point mappings are accurate
  // FIXME: Support XF and TF types
  if (!DestWidth) {
    Diag(AttrLoc, diag::err_machine_mode) << 0 /*Unknown*/ << Name;
    return;
  }
 
  QualType OldTy;
  if (const auto *TD = dyn_cast<TypedefNameDecl>(D))
    OldTy = TD->getUnderlyingType();
  else if (const auto *ED = dyn_cast<EnumDecl>(D)) {
    // Something like 'typedef enum { X } __attribute__((mode(XX))) T;'.
    // Try to get type from enum declaration, default to int.
    OldTy = ED->getIntegerType();
    if (OldTy.isNull())
      OldTy = Context.IntTy;
  } else
    OldTy = cast<ValueDecl>(D)->getType();
 
  if (OldTy->isDependentType()) {
    D->addAttr(::new (Context) ModeAttr(Context, CI, Name));
    return;
  }
 
  // Base type can also be a vector type (see PR17453).
  // Distinguish between base type and base element type.
  QualType OldElemTy = OldTy;
  if (const auto *VT = OldTy->getAs<VectorType>())
    OldElemTy = VT->getElementType();
 
  // GCC allows 'mode' attribute on enumeration types (even incomplete), except
  // for vector modes. So, 'enum X __attribute__((mode(QI)));' forms a complete
  // type, 'enum { A } __attribute__((mode(V4SI)))' is rejected.
  if ((isa<EnumDecl>(D) || OldElemTy->getAs<EnumType>()) &&
      VectorSize.getBoolValue()) {
    Diag(AttrLoc, diag::err_enum_mode_vector_type) << Name << CI.getRange();
    return;
  }
  bool IntegralOrAnyEnumType = (OldElemTy->isIntegralOrEnumerationType() &&
                                !OldElemTy->isBitIntType()) ||
                               OldElemTy->getAs<EnumType>();
 
  if (!OldElemTy->getAs<BuiltinType>() && !OldElemTy->isComplexType() &&
      !IntegralOrAnyEnumType)
    Diag(AttrLoc, diag::err_mode_not_primitive);
  else if (IntegerMode) {
    if (!IntegralOrAnyEnumType)
      Diag(AttrLoc, diag::err_mode_wrong_type);
  } else if (ComplexMode) {
    if (!OldElemTy->isComplexType())
      Diag(AttrLoc, diag::err_mode_wrong_type);
  } else {
    if (!OldElemTy->isFloatingType())
      Diag(AttrLoc, diag::err_mode_wrong_type);
  }
 
  QualType NewElemTy;
 
  if (IntegerMode)
    NewElemTy = Context.getIntTypeForBitwidth(DestWidth,
                                              OldElemTy->isSignedIntegerType());
  else
    NewElemTy = Context.getRealTypeForBitwidth(DestWidth, ExplicitType);
 
  if (NewElemTy.isNull()) {
    Diag(AttrLoc, diag::err_machine_mode) << 1 /*Unsupported*/ << Name;
    return;
  }
 
  if (ComplexMode) {
    NewElemTy = Context.getComplexType(NewElemTy);
  }
 
  QualType NewTy = NewElemTy;
  if (VectorSize.getBoolValue()) {
    NewTy = Context.getVectorType(NewTy, VectorSize.getZExtValue(),
                                  VectorType::GenericVector);
  } else if (const auto *OldVT = OldTy->getAs<VectorType>()) {
    // Complex machine mode does not support base vector types.
    if (ComplexMode) {
      Diag(AttrLoc, diag::err_complex_mode_vector_type);
      return;
    }
    unsigned NumElements = Context.getTypeSize(OldElemTy) *
                           OldVT->getNumElements() /
                           Context.getTypeSize(NewElemTy);
    NewTy =
        Context.getVectorType(NewElemTy, NumElements, OldVT->getVectorKind());
  }
 
  if (NewTy.isNull()) {
    Diag(AttrLoc, diag::err_mode_wrong_type);
    return;
  }
 
  // Install the new type.
  if (auto *TD = dyn_cast<TypedefNameDecl>(D))
    TD->setModedTypeSourceInfo(TD->getTypeSourceInfo(), NewTy);
  else if (auto *ED = dyn_cast<EnumDecl>(D))
    ED->setIntegerType(NewTy);
  else
    cast<ValueDecl>(D)->setType(NewTy);
 
  D->addAttr(::new (Context) ModeAttr(Context, CI, Name));
}
 
static void handleNoDebugAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  D->addAttr(::new (S.Context) NoDebugAttr(S.Context, AL));
}
 
AlwaysInlineAttr *Sema::mergeAlwaysInlineAttr(Decl *D,
                                              const AttributeCommonInfo &CI,
                                              const IdentifierInfo *Ident) {
  if (OptimizeNoneAttr *Optnone = D->getAttr<OptimizeNoneAttr>()) {
    Diag(CI.getLoc(), diag::warn_attribute_ignored) << Ident;
    Diag(Optnone->getLocation(), diag::note_conflicting_attribute);
    return nullptr;
  }
 
  if (D->hasAttr<AlwaysInlineAttr>())
    return nullptr;
 
  return ::new (Context) AlwaysInlineAttr(Context, CI);
}
 
InternalLinkageAttr *Sema::mergeInternalLinkageAttr(Decl *D,
                                                    const ParsedAttr &AL) {
  if (const auto *VD = dyn_cast<VarDecl>(D)) {
    // Attribute applies to Var but not any subclass of it (like ParmVar,
    // ImplicitParm or VarTemplateSpecialization).
    if (VD->getKind() != Decl::Var) {
      Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type)
          << AL << (getLangOpts().CPlusPlus ? ExpectedFunctionVariableOrClass
                                            : ExpectedVariableOrFunction);
      return nullptr;
    }
    // Attribute does not apply to non-static local variables.
    if (VD->hasLocalStorage()) {
      Diag(VD->getLocation(), diag::warn_internal_linkage_local_storage);
      return nullptr;
    }
  }
 
  return ::new (Context) InternalLinkageAttr(Context, AL);
}
InternalLinkageAttr *
Sema::mergeInternalLinkageAttr(Decl *D, const InternalLinkageAttr &AL) {
  if (const auto *VD = dyn_cast<VarDecl>(D)) {
    // Attribute applies to Var but not any subclass of it (like ParmVar,
    // ImplicitParm or VarTemplateSpecialization).
    if (VD->getKind() != Decl::Var) {
      Diag(AL.getLocation(), diag::warn_attribute_wrong_decl_type)
          << &AL << (getLangOpts().CPlusPlus ? ExpectedFunctionVariableOrClass
                                             : ExpectedVariableOrFunction);
      return nullptr;
    }
    // Attribute does not apply to non-static local variables.
    if (VD->hasLocalStorage()) {
      Diag(VD->getLocation(), diag::warn_internal_linkage_local_storage);
      return nullptr;
    }
  }
 
  return ::new (Context) InternalLinkageAttr(Context, AL);
}
 
MinSizeAttr *Sema::mergeMinSizeAttr(Decl *D, const AttributeCommonInfo &CI) {
  if (OptimizeNoneAttr *Optnone = D->getAttr<OptimizeNoneAttr>()) {
    Diag(CI.getLoc(), diag::warn_attribute_ignored) << "'minsize'";
    Diag(Optnone->getLocation(), diag::note_conflicting_attribute);
    return nullptr;
  }
 
  if (D->hasAttr<MinSizeAttr>())
    return nullptr;
 
  return ::new (Context) MinSizeAttr(Context, CI);
}
 
SwiftNameAttr *Sema::mergeSwiftNameAttr(Decl *D, const SwiftNameAttr &SNA,
                                        StringRef Name) {
  if (const auto *PrevSNA = D->getAttr<SwiftNameAttr>()) {
    if (PrevSNA->getName() != Name && !PrevSNA->isImplicit()) {
      Diag(PrevSNA->getLocation(), diag::err_attributes_are_not_compatible)
          << PrevSNA << &SNA;
      Diag(SNA.getLoc(), diag::note_conflicting_attribute);
    }
 
    D->dropAttr<SwiftNameAttr>();
  }
  return ::new (Context) SwiftNameAttr(Context, SNA, Name);
}
 
OptimizeNoneAttr *Sema::mergeOptimizeNoneAttr(Decl *D,
                                              const AttributeCommonInfo &CI) {
  if (AlwaysInlineAttr *Inline = D->getAttr<AlwaysInlineAttr>()) {
    Diag(Inline->getLocation(), diag::warn_attribute_ignored) << Inline;
    Diag(CI.getLoc(), diag::note_conflicting_attribute);
    D->dropAttr<AlwaysInlineAttr>();
  }
  if (MinSizeAttr *MinSize = D->getAttr<MinSizeAttr>()) {
    Diag(MinSize->getLocation(), diag::warn_attribute_ignored) << MinSize;
    Diag(CI.getLoc(), diag::note_conflicting_attribute);
    D->dropAttr<MinSizeAttr>();
  }
 
  if (D->hasAttr<OptimizeNoneAttr>())
    return nullptr;
 
  return ::new (Context) OptimizeNoneAttr(Context, CI);
}
 
static void handleAlwaysInlineAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (AlwaysInlineAttr *Inline =
          S.mergeAlwaysInlineAttr(D, AL, AL.getAttrName()))
    D->addAttr(Inline);
}
 
static void handleMinSizeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (MinSizeAttr *MinSize = S.mergeMinSizeAttr(D, AL))
    D->addAttr(MinSize);
}
 
static void handleOptimizeNoneAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (OptimizeNoneAttr *Optnone = S.mergeOptimizeNoneAttr(D, AL))
    D->addAttr(Optnone);
}
 
static void handleConstantAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  const auto *VD = cast<VarDecl>(D);
  if (VD->hasLocalStorage()) {
    S.Diag(AL.getLoc(), diag::err_cuda_nonstatic_constdev);
    return;
  }
  // constexpr variable may already get an implicit constant attr, which should
  // be replaced by the explicit constant attr.
  if (auto *A = D->getAttr<CUDAConstantAttr>()) {
    if (!A->isImplicit())
      return;
    D->dropAttr<CUDAConstantAttr>();
  }
  D->addAttr(::new (S.Context) CUDAConstantAttr(S.Context, AL));
}
 
static void handleSharedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  const auto *VD = cast<VarDecl>(D);
  // extern __shared__ is only allowed on arrays with no length (e.g.
  // "int x[]").
  if (!S.getLangOpts().GPURelocatableDeviceCode && VD->hasExternalStorage() &&
      !isa<IncompleteArrayType>(VD->getType())) {
    S.Diag(AL.getLoc(), diag::err_cuda_extern_shared) << VD;
    return;
  }
  if (S.getLangOpts().CUDA && VD->hasLocalStorage() &&
      S.CUDADiagIfHostCode(AL.getLoc(), diag::err_cuda_host_shared)
          << S.CurrentCUDATarget())
    return;
  D->addAttr(::new (S.Context) CUDASharedAttr(S.Context, AL));
}
 
static void handleGlobalAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  const auto *FD = cast<FunctionDecl>(D);
  if (!FD->getReturnType()->isVoidType() &&
      !FD->getReturnType()->getAs<AutoType>() &&
      !FD->getReturnType()->isInstantiationDependentType()) {
    SourceRange RTRange = FD->getReturnTypeSourceRange();
    S.Diag(FD->getTypeSpecStartLoc(), diag::err_kern_type_not_void_return)
        << FD->getType()
        << (RTRange.isValid() ? FixItHint::CreateReplacement(RTRange, "void")
                              : FixItHint());
    return;
  }
  if (const auto *Method = dyn_cast<CXXMethodDecl>(FD)) {
    if (Method->isInstance()) {
      S.Diag(Method->getBeginLoc(), diag::err_kern_is_nonstatic_method)
          << Method;
      return;
    }
    S.Diag(Method->getBeginLoc(), diag::warn_kern_is_method) << Method;
  }
  // Only warn for "inline" when compiling for host, to cut down on noise.
  if (FD->isInlineSpecified() && !S.getLangOpts().CUDAIsDevice)
    S.Diag(FD->getBeginLoc(), diag::warn_kern_is_inline) << FD;
 
  D->addAttr(::new (S.Context) CUDAGlobalAttr(S.Context, AL));
  // In host compilation the kernel is emitted as a stub function, which is
  // a helper function for launching the kernel. The instructions in the helper