text: //===- ClangAttrEmitter.cpp - Generate Clang attribute handling =-*- C++ -*--=//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // These tablegen backends emit Clang attribute processing code
  //
  //===----------------------------------------------------------------------===//
  
  #include "TableGenBackends.h"
  #include "ASTTableGen.h"
  
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/DenseSet.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/StringExtras.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/StringSet.h"
  #include "llvm/ADT/StringSwitch.h"
  #include "llvm/ADT/iterator_range.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/raw_ostream.h"
  #include "llvm/TableGen/Error.h"
  #include "llvm/TableGen/Record.h"
  #include "llvm/TableGen/StringMatcher.h"
  #include "llvm/TableGen/TableGenBackend.h"
  #include <algorithm>
  #include <cassert>
  #include <cctype>
  #include <cstddef>
  #include <cstdint>
  #include <map>
  #include <memory>
  #include <set>
  #include <sstream>
  #include <string>
  #include <utility>
  #include <vector>
  
  using namespace llvm;
  
  namespace {
  
  class FlattenedSpelling {
    std::string V, N, NS;
    bool K = false;
  
  public:
    FlattenedSpelling(const std::string &Variety, const std::string &Name,
                      const std::string &Namespace, bool KnownToGCC) :
      V(Variety), N(Name), NS(Namespace), K(KnownToGCC) {}
    explicit FlattenedSpelling(const Record &Spelling)
        : V(std::string(Spelling.getValueAsString("Variety"))),
          N(std::string(Spelling.getValueAsString("Name"))) {
      assert(V != "GCC" && V != "Clang" &&
             "Given a GCC spelling, which means this hasn't been flattened!");
      if (V == "CXX11" || V == "C2x" || V == "Pragma")
        NS = std::string(Spelling.getValueAsString("Namespace"));
    }
  
    const std::string &variety() const { return V; }
    const std::string &name() const { return N; }
    const std::string &nameSpace() const { return NS; }
    bool knownToGCC() const { return K; }
  };
  
  } // end anonymous namespace
  
  static std::vector<FlattenedSpelling>
  GetFlattenedSpellings(const Record &Attr) {
    std::vector<Record *> Spellings = Attr.getValueAsListOfDefs("Spellings");
    std::vector<FlattenedSpelling> Ret;
  
    for (const auto &Spelling : Spellings) {
      StringRef Variety = Spelling->getValueAsString("Variety");
      StringRef Name = Spelling->getValueAsString("Name");
      if (Variety == "GCC") {
        Ret.emplace_back("GNU", std::string(Name), "", true);
        Ret.emplace_back("CXX11", std::string(Name), "gnu", true);
        if (Spelling->getValueAsBit("AllowInC"))
          Ret.emplace_back("C2x", std::string(Name), "gnu", true);
      } else if (Variety == "Clang") {
        Ret.emplace_back("GNU", std::string(Name), "", false);
        Ret.emplace_back("CXX11", std::string(Name), "clang", false);
        if (Spelling->getValueAsBit("AllowInC"))
          Ret.emplace_back("C2x", std::string(Name), "clang", false);
      } else
        Ret.push_back(FlattenedSpelling(*Spelling));
    }
  
    return Ret;
  }
  
  static std::string ReadPCHRecord(StringRef type) {
    return StringSwitch<std::string>(type)
        .EndsWith("Decl *", "Record.GetLocalDeclAs<" +
                                std::string(type.data(), 0, type.size() - 1) +
                                ">(Record.readInt())")
        .Case("TypeSourceInfo *", "Record.readTypeSourceInfo()")
        .Case("Expr *", "Record.readExpr()")
        .Case("IdentifierInfo *", "Record.readIdentifier()")
        .Case("StringRef", "Record.readString()")
        .Case("ParamIdx", "ParamIdx::deserialize(Record.readInt())")
        .Case("OMPTraitInfo *", "Record.readOMPTraitInfo()")
        .Default("Record.readInt()");
  }
  
  // Get a type that is suitable for storing an object of the specified type.
  static StringRef getStorageType(StringRef type) {
    return StringSwitch<StringRef>(type)
      .Case("StringRef", "std::string")
      .Default(type);
  }
  
  // Assumes that the way to get the value is SA->getname()
  static std::string WritePCHRecord(StringRef type, StringRef name) {
    return "Record." +
           StringSwitch<std::string>(type)
               .EndsWith("Decl *", "AddDeclRef(" + std::string(name) + ");\n")
               .Case("TypeSourceInfo *",
                     "AddTypeSourceInfo(" + std::string(name) + ");\n")
               .Case("Expr *", "AddStmt(" + std::string(name) + ");\n")
               .Case("IdentifierInfo *",
                     "AddIdentifierRef(" + std::string(name) + ");\n")
               .Case("StringRef", "AddString(" + std::string(name) + ");\n")
               .Case("ParamIdx",
                     "push_back(" + std::string(name) + ".serialize());\n")
               .Case("OMPTraitInfo *",
                     "writeOMPTraitInfo(" + std::string(name) + ");\n")
               .Default("push_back(" + std::string(name) + ");\n");
  }
  
  // Normalize attribute name by removing leading and trailing
  // underscores. For example, __foo, foo__, __foo__ would
  // become foo.
  static StringRef NormalizeAttrName(StringRef AttrName) {
    AttrName.consume_front("__");
    AttrName.consume_back("__");
    return AttrName;
  }
  
  // Normalize the name by removing any and all leading and trailing underscores.
  // This is different from NormalizeAttrName in that it also handles names like
  // _pascal and __pascal.
  static StringRef NormalizeNameForSpellingComparison(StringRef Name) {
    return Name.trim("_");
  }
  
  // Normalize the spelling of a GNU attribute (i.e. "x" in "__attribute__((x))"),
  // removing "__" if it appears at the beginning and end of the attribute's name.
  static StringRef NormalizeGNUAttrSpelling(StringRef AttrSpelling) {
    if (AttrSpelling.startswith("__") && AttrSpelling.endswith("__")) {
      AttrSpelling = AttrSpelling.substr(2, AttrSpelling.size() - 4);
    }
  
    return AttrSpelling;
  }
  
  typedef std::vector<std::pair<std::string, const Record *>> ParsedAttrMap;
  
  static ParsedAttrMap getParsedAttrList(const RecordKeeper &Records,
                                         ParsedAttrMap *Dupes = nullptr) {
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    std::set<std::string> Seen;
    ParsedAttrMap R;
    for (const auto *Attr : Attrs) {
      if (Attr->getValueAsBit("SemaHandler")) {
        std::string AN;
        if (Attr->isSubClassOf("TargetSpecificAttr") &&
            !Attr->isValueUnset("ParseKind")) {
          AN = std::string(Attr->getValueAsString("ParseKind"));
  
          // If this attribute has already been handled, it does not need to be
          // handled again.
          if (Seen.find(AN) != Seen.end()) {
            if (Dupes)
              Dupes->push_back(std::make_pair(AN, Attr));
            continue;
          }
          Seen.insert(AN);
        } else
          AN = NormalizeAttrName(Attr->getName()).str();
  
        R.push_back(std::make_pair(AN, Attr));
      }
    }
    return R;
  }
  
  namespace {
  
    class Argument {
      std::string lowerName, upperName;
      StringRef attrName;
      bool isOpt;
      bool Fake;
  
    public:
      Argument(const Record &Arg, StringRef Attr)
          : lowerName(std::string(Arg.getValueAsString("Name"))),
            upperName(lowerName), attrName(Attr), isOpt(false), Fake(false) {
        if (!lowerName.empty()) {
          lowerName[0] = std::tolower(lowerName[0]);
          upperName[0] = std::toupper(upperName[0]);
        }
        // Work around MinGW's macro definition of 'interface' to 'struct'. We
        // have an attribute argument called 'Interface', so only the lower case
        // name conflicts with the macro definition.
        if (lowerName == "interface")
          lowerName = "interface_";
      }
      virtual ~Argument() = default;
  
      StringRef getLowerName() const { return lowerName; }
      StringRef getUpperName() const { return upperName; }
      StringRef getAttrName() const { return attrName; }
  
      bool isOptional() const { return isOpt; }
      void setOptional(bool set) { isOpt = set; }
  
      bool isFake() const { return Fake; }
      void setFake(bool fake) { Fake = fake; }
  
      // These functions print the argument contents formatted in different ways.
      virtual void writeAccessors(raw_ostream &OS) const = 0;
      virtual void writeAccessorDefinitions(raw_ostream &OS) const {}
      virtual void writeASTVisitorTraversal(raw_ostream &OS) const {}
      virtual void writeCloneArgs(raw_ostream &OS) const = 0;
      virtual void writeTemplateInstantiationArgs(raw_ostream &OS) const = 0;
      virtual void writeTemplateInstantiation(raw_ostream &OS) const {}
      virtual void writeCtorBody(raw_ostream &OS) const {}
      virtual void writeCtorInitializers(raw_ostream &OS) const = 0;
      virtual void writeCtorDefaultInitializers(raw_ostream &OS) const = 0;
      virtual void writeCtorParameters(raw_ostream &OS) const = 0;
      virtual void writeDeclarations(raw_ostream &OS) const = 0;
      virtual void writePCHReadArgs(raw_ostream &OS) const = 0;
      virtual void writePCHReadDecls(raw_ostream &OS) const = 0;
      virtual void writePCHWrite(raw_ostream &OS) const = 0;
      virtual std::string getIsOmitted() const { return "false"; }
      virtual void writeValue(raw_ostream &OS) const = 0;
      virtual void writeDump(raw_ostream &OS) const = 0;
      virtual void writeDumpChildren(raw_ostream &OS) const {}
      virtual void writeHasChildren(raw_ostream &OS) const { OS << "false"; }
  
      virtual bool isEnumArg() const { return false; }
      virtual bool isVariadicEnumArg() const { return false; }
      virtual bool isVariadic() const { return false; }
  
      virtual void writeImplicitCtorArgs(raw_ostream &OS) const {
        OS << getUpperName();
      }
    };
  
    class SimpleArgument : public Argument {
      std::string type;
  
    public:
      SimpleArgument(const Record &Arg, StringRef Attr, std::string T)
          : Argument(Arg, Attr), type(std::move(T)) {}
  
      std::string getType() const { return type; }
  
      void writeAccessors(raw_ostream &OS) const override {
        OS << "  " << type << " get" << getUpperName() << "() const {\n";
        OS << "    return " << getLowerName() << ";\n";
        OS << "  }";
      }
  
      void writeCloneArgs(raw_ostream &OS) const override {
        OS << getLowerName();
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        OS << "A->get" << getUpperName() << "()";
      }
  
      void writeCtorInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "(" << getUpperName() << ")";
      }
  
      void writeCtorDefaultInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "()";
      }
  
      void writeCtorParameters(raw_ostream &OS) const override {
        OS << type << " " << getUpperName();
      }
  
      void writeDeclarations(raw_ostream &OS) const override {
        OS << type << " " << getLowerName() << ";";
      }
  
      void writePCHReadDecls(raw_ostream &OS) const override {
        std::string read = ReadPCHRecord(type);
        OS << "    " << type << " " << getLowerName() << " = " << read << ";\n";
      }
  
      void writePCHReadArgs(raw_ostream &OS) const override {
        OS << getLowerName();
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "    "
           << WritePCHRecord(type,
                             "SA->get" + std::string(getUpperName()) + "()");
      }
  
      std::string getIsOmitted() const override {
        if (type == "IdentifierInfo *")
          return "!get" + getUpperName().str() + "()";
        if (type == "TypeSourceInfo *")
          return "!get" + getUpperName().str() + "Loc()";
        if (type == "ParamIdx")
          return "!get" + getUpperName().str() + "().isValid()";
        return "false";
      }
  
      void writeValue(raw_ostream &OS) const override {
        if (type == "FunctionDecl *")
          OS << "\" << get" << getUpperName()
             << "()->getNameInfo().getAsString() << \"";
        else if (type == "IdentifierInfo *")
          // Some non-optional (comma required) identifier arguments can be the
          // empty string but are then recorded as a nullptr.
          OS << "\" << (get" << getUpperName() << "() ? get" << getUpperName()
             << "()->getName() : \"\") << \"";
        else if (type == "VarDecl *")
          OS << "\" << get" << getUpperName() << "()->getName() << \"";
        else if (type == "TypeSourceInfo *")
          OS << "\" << get" << getUpperName() << "().getAsString() << \"";
        else if (type == "ParamIdx")
          OS << "\" << get" << getUpperName() << "().getSourceIndex() << \"";
        else
          OS << "\" << get" << getUpperName() << "() << \"";
      }
  
      void writeDump(raw_ostream &OS) const override {
        if (StringRef(type).endswith("Decl *")) {
          OS << "    OS << \" \";\n";
          OS << "    dumpBareDeclRef(SA->get" << getUpperName() << "());\n";
        } else if (type == "IdentifierInfo *") {
          // Some non-optional (comma required) identifier arguments can be the
          // empty string but are then recorded as a nullptr.
          OS << "    if (SA->get" << getUpperName() << "())\n"
             << "      OS << \" \" << SA->get" << getUpperName()
             << "()->getName();\n";
        } else if (type == "TypeSourceInfo *") {
          if (isOptional())
            OS << "    if (SA->get" << getUpperName() << "Loc())";
          OS << "    OS << \" \" << SA->get" << getUpperName()
             << "().getAsString();\n";
        } else if (type == "bool") {
          OS << "    if (SA->get" << getUpperName() << "()) OS << \" "
             << getUpperName() << "\";\n";
        } else if (type == "int" || type == "unsigned") {
          OS << "    OS << \" \" << SA->get" << getUpperName() << "();\n";
        } else if (type == "ParamIdx") {
          if (isOptional())
            OS << "    if (SA->get" << getUpperName() << "().isValid())\n  ";
          OS << "    OS << \" \" << SA->get" << getUpperName()
             << "().getSourceIndex();\n";
        } else if (type == "OMPTraitInfo *") {
          OS << "    OS << \" \" << SA->get" << getUpperName() << "();\n";
        } else {
          llvm_unreachable("Unknown SimpleArgument type!");
        }
      }
    };
  
    class DefaultSimpleArgument : public SimpleArgument {
      int64_t Default;
  
    public:
      DefaultSimpleArgument(const Record &Arg, StringRef Attr,
                            std::string T, int64_t Default)
        : SimpleArgument(Arg, Attr, T), Default(Default) {}
  
      void writeAccessors(raw_ostream &OS) const override {
        SimpleArgument::writeAccessors(OS);
  
        OS << "\n\n  static const " << getType() << " Default" << getUpperName()
           << " = ";
        if (getType() == "bool")
          OS << (Default != 0 ? "true" : "false");
        else
          OS << Default;
        OS << ";";
      }
    };
  
    class StringArgument : public Argument {
    public:
      StringArgument(const Record &Arg, StringRef Attr)
        : Argument(Arg, Attr)
      {}
  
      void writeAccessors(raw_ostream &OS) const override {
        OS << "  llvm::StringRef get" << getUpperName() << "() const {\n";
        OS << "    return llvm::StringRef(" << getLowerName() << ", "
           << getLowerName() << "Length);\n";
        OS << "  }\n";
        OS << "  unsigned get" << getUpperName() << "Length() const {\n";
        OS << "    return " << getLowerName() << "Length;\n";
        OS << "  }\n";
        OS << "  void set" << getUpperName()
           << "(ASTContext &C, llvm::StringRef S) {\n";
        OS << "    " << getLowerName() << "Length = S.size();\n";
        OS << "    this->" << getLowerName() << " = new (C, 1) char ["
           << getLowerName() << "Length];\n";
        OS << "    if (!S.empty())\n";
        OS << "      std::memcpy(this->" << getLowerName() << ", S.data(), "
           << getLowerName() << "Length);\n";
        OS << "  }";
      }
  
      void writeCloneArgs(raw_ostream &OS) const override {
        OS << "get" << getUpperName() << "()";
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        OS << "A->get" << getUpperName() << "()";
      }
  
      void writeCtorBody(raw_ostream &OS) const override {
        OS << "    if (!" << getUpperName() << ".empty())\n";
        OS << "      std::memcpy(" << getLowerName() << ", " << getUpperName()
           << ".data(), " << getLowerName() << "Length);\n";
      }
  
      void writeCtorInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "Length(" << getUpperName() << ".size()),"
           << getLowerName() << "(new (Ctx, 1) char[" << getLowerName()
           << "Length])";
      }
  
      void writeCtorDefaultInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "Length(0)," << getLowerName() << "(nullptr)";
      }
  
      void writeCtorParameters(raw_ostream &OS) const override {
        OS << "llvm::StringRef " << getUpperName();
      }
  
      void writeDeclarations(raw_ostream &OS) const override {
        OS << "unsigned " << getLowerName() << "Length;\n";
        OS << "char *" << getLowerName() << ";";
      }
  
      void writePCHReadDecls(raw_ostream &OS) const override {
        OS << "    std::string " << getLowerName()
           << "= Record.readString();\n";
      }
  
      void writePCHReadArgs(raw_ostream &OS) const override {
        OS << getLowerName();
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "    Record.AddString(SA->get" << getUpperName() << "());\n";
      }
  
      void writeValue(raw_ostream &OS) const override {
        OS << "\\\"\" << get" << getUpperName() << "() << \"\\\"";
      }
  
      void writeDump(raw_ostream &OS) const override {
        OS << "    OS << \" \\\"\" << SA->get" << getUpperName()
           << "() << \"\\\"\";\n";
      }
    };
  
    class AlignedArgument : public Argument {
    public:
      AlignedArgument(const Record &Arg, StringRef Attr)
        : Argument(Arg, Attr)
      {}
  
      void writeAccessors(raw_ostream &OS) const override {
        OS << "  bool is" << getUpperName() << "Dependent() const;\n";
        OS << "  bool is" << getUpperName() << "ErrorDependent() const;\n";
  
        OS << "  unsigned get" << getUpperName() << "(ASTContext &Ctx) const;\n";
  
        OS << "  bool is" << getUpperName() << "Expr() const {\n";
        OS << "    return is" << getLowerName() << "Expr;\n";
        OS << "  }\n";
  
        OS << "  Expr *get" << getUpperName() << "Expr() const {\n";
        OS << "    assert(is" << getLowerName() << "Expr);\n";
        OS << "    return " << getLowerName() << "Expr;\n";
        OS << "  }\n";
  
        OS << "  TypeSourceInfo *get" << getUpperName() << "Type() const {\n";
        OS << "    assert(!is" << getLowerName() << "Expr);\n";
        OS << "    return " << getLowerName() << "Type;\n";
        OS << "  }";
      }
  
      void writeAccessorDefinitions(raw_ostream &OS) const override {
        OS << "bool " << getAttrName() << "Attr::is" << getUpperName()
           << "Dependent() const {\n";
        OS << "  if (is" << getLowerName() << "Expr)\n";
        OS << "    return " << getLowerName() << "Expr && (" << getLowerName()
           << "Expr->isValueDependent() || " << getLowerName()
           << "Expr->isTypeDependent());\n";
        OS << "  else\n";
        OS << "    return " << getLowerName()
           << "Type->getType()->isDependentType();\n";
        OS << "}\n";
  
        OS << "bool " << getAttrName() << "Attr::is" << getUpperName()
           << "ErrorDependent() const {\n";
        OS << "  if (is" << getLowerName() << "Expr)\n";
        OS << "    return " << getLowerName() << "Expr && " << getLowerName()
           << "Expr->containsErrors();\n";
        OS << "  return " << getLowerName()
           << "Type->getType()->containsErrors();\n";
        OS << "}\n";
  
        // FIXME: Do not do the calculation here
        // FIXME: Handle types correctly
        // A null pointer means maximum alignment
        OS << "unsigned " << getAttrName() << "Attr::get" << getUpperName()
           << "(ASTContext &Ctx) const {\n";
        OS << "  assert(!is" << getUpperName() << "Dependent());\n";
        OS << "  if (is" << getLowerName() << "Expr)\n";
        OS << "    return " << getLowerName() << "Expr ? " << getLowerName()
           << "Expr->EvaluateKnownConstInt(Ctx).getZExtValue()"
           << " * Ctx.getCharWidth() : "
           << "Ctx.getTargetDefaultAlignForAttributeAligned();\n";
        OS << "  else\n";
        OS << "    return 0; // FIXME\n";
        OS << "}\n";
      }
  
      void writeASTVisitorTraversal(raw_ostream &OS) const override {
        StringRef Name = getUpperName();
        OS << "  if (A->is" << Name << "Expr()) {\n"
           << "    if (!getDerived().TraverseStmt(A->get" << Name << "Expr()))\n"
           << "      return false;\n"
           << "  } else if (auto *TSI = A->get" << Name << "Type()) {\n"
           << "    if (!getDerived().TraverseTypeLoc(TSI->getTypeLoc()))\n"
           << "      return false;\n"
           << "  }\n";
      }
  
      void writeCloneArgs(raw_ostream &OS) const override {
        OS << "is" << getLowerName() << "Expr, is" << getLowerName()
           << "Expr ? static_cast<void*>(" << getLowerName()
           << "Expr) : " << getLowerName()
           << "Type";
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        // FIXME: move the definition in Sema::InstantiateAttrs to here.
        // In the meantime, aligned attributes are cloned.
      }
  
      void writeCtorBody(raw_ostream &OS) const override {
        OS << "    if (is" << getLowerName() << "Expr)\n";
        OS << "       " << getLowerName() << "Expr = reinterpret_cast<Expr *>("
           << getUpperName() << ");\n";
        OS << "    else\n";
        OS << "       " << getLowerName()
           << "Type = reinterpret_cast<TypeSourceInfo *>(" << getUpperName()
           << ");\n";
      }
  
      void writeCtorInitializers(raw_ostream &OS) const override {
        OS << "is" << getLowerName() << "Expr(Is" << getUpperName() << "Expr)";
      }
  
      void writeCtorDefaultInitializers(raw_ostream &OS) const override {
        OS << "is" << getLowerName() << "Expr(false)";
      }
  
      void writeCtorParameters(raw_ostream &OS) const override {
        OS << "bool Is" << getUpperName() << "Expr, void *" << getUpperName();
      }
  
      void writeImplicitCtorArgs(raw_ostream &OS) const override {
        OS << "Is" << getUpperName() << "Expr, " << getUpperName();
      }
  
      void writeDeclarations(raw_ostream &OS) const override {
        OS << "bool is" << getLowerName() << "Expr;\n";
        OS << "union {\n";
        OS << "Expr *" << getLowerName() << "Expr;\n";
        OS << "TypeSourceInfo *" << getLowerName() << "Type;\n";
        OS << "};";
      }
  
      void writePCHReadArgs(raw_ostream &OS) const override {
        OS << "is" << getLowerName() << "Expr, " << getLowerName() << "Ptr";
      }
  
      void writePCHReadDecls(raw_ostream &OS) const override {
        OS << "    bool is" << getLowerName() << "Expr = Record.readInt();\n";
        OS << "    void *" << getLowerName() << "Ptr;\n";
        OS << "    if (is" << getLowerName() << "Expr)\n";
        OS << "      " << getLowerName() << "Ptr = Record.readExpr();\n";
        OS << "    else\n";
        OS << "      " << getLowerName()
           << "Ptr = Record.readTypeSourceInfo();\n";
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "    Record.push_back(SA->is" << getUpperName() << "Expr());\n";
        OS << "    if (SA->is" << getUpperName() << "Expr())\n";
        OS << "      Record.AddStmt(SA->get" << getUpperName() << "Expr());\n";
        OS << "    else\n";
        OS << "      Record.AddTypeSourceInfo(SA->get" << getUpperName()
           << "Type());\n";
      }
  
      std::string getIsOmitted() const override {
        return "!is" + getLowerName().str() + "Expr || !" + getLowerName().str()
               + "Expr";
      }
  
      void writeValue(raw_ostream &OS) const override {
        OS << "\";\n";
        OS << "    " << getLowerName()
           << "Expr->printPretty(OS, nullptr, Policy);\n";
        OS << "    OS << \"";
      }
  
      void writeDump(raw_ostream &OS) const override {
        OS << "    if (!SA->is" << getUpperName() << "Expr())\n";
        OS << "      dumpType(SA->get" << getUpperName()
           << "Type()->getType());\n";
      }
  
      void writeDumpChildren(raw_ostream &OS) const override {
        OS << "    if (SA->is" << getUpperName() << "Expr())\n";
        OS << "      Visit(SA->get" << getUpperName() << "Expr());\n";
      }
  
      void writeHasChildren(raw_ostream &OS) const override {
        OS << "SA->is" << getUpperName() << "Expr()";
      }
    };
  
    class VariadicArgument : public Argument {
      std::string Type, ArgName, ArgSizeName, RangeName;
  
    protected:
      // Assumed to receive a parameter: raw_ostream OS.
      virtual void writeValueImpl(raw_ostream &OS) const {
        OS << "    OS << Val;\n";
      }
      // Assumed to receive a parameter: raw_ostream OS.
      virtual void writeDumpImpl(raw_ostream &OS) const {
        OS << "      OS << \" \" << Val;\n";
      }
  
    public:
      VariadicArgument(const Record &Arg, StringRef Attr, std::string T)
          : Argument(Arg, Attr), Type(std::move(T)),
            ArgName(getLowerName().str() + "_"), ArgSizeName(ArgName + "Size"),
            RangeName(std::string(getLowerName())) {}
  
      const std::string &getType() const { return Type; }
      const std::string &getArgName() const { return ArgName; }
      const std::string &getArgSizeName() const { return ArgSizeName; }
      bool isVariadic() const override { return true; }
  
      void writeAccessors(raw_ostream &OS) const override {
        std::string IteratorType = getLowerName().str() + "_iterator";
        std::string BeginFn = getLowerName().str() + "_begin()";
        std::string EndFn = getLowerName().str() + "_end()";
  
        OS << "  typedef " << Type << "* " << IteratorType << ";\n";
        OS << "  " << IteratorType << " " << BeginFn << " const {"
           << " return " << ArgName << "; }\n";
        OS << "  " << IteratorType << " " << EndFn << " const {"
           << " return " << ArgName << " + " << ArgSizeName << "; }\n";
        OS << "  unsigned " << getLowerName() << "_size() const {"
           << " return " << ArgSizeName << "; }\n";
        OS << "  llvm::iterator_range<" << IteratorType << "> " << RangeName
           << "() const { return llvm::make_range(" << BeginFn << ", " << EndFn
           << "); }\n";
      }
  
      void writeCloneArgs(raw_ostream &OS) const override {
        OS << ArgName << ", " << ArgSizeName;
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        // This isn't elegant, but we have to go through public methods...
        OS << "A->" << getLowerName() << "_begin(), "
           << "A->" << getLowerName() << "_size()";
      }
  
      void writeASTVisitorTraversal(raw_ostream &OS) const override {
        // FIXME: Traverse the elements.
      }
  
      void writeCtorBody(raw_ostream &OS) const override {
        OS << "  std::copy(" << getUpperName() << ", " << getUpperName() << " + "
           << ArgSizeName << ", " << ArgName << ");\n";
      }
  
      void writeCtorInitializers(raw_ostream &OS) const override {
        OS << ArgSizeName << "(" << getUpperName() << "Size), "
           << ArgName << "(new (Ctx, 16) " << getType() << "["
           << ArgSizeName << "])";
      }
  
      void writeCtorDefaultInitializers(raw_ostream &OS) const override {
        OS << ArgSizeName << "(0), " << ArgName << "(nullptr)";
      }
  
      void writeCtorParameters(raw_ostream &OS) const override {
        OS << getType() << " *" << getUpperName() << ", unsigned "
           << getUpperName() << "Size";
      }
  
      void writeImplicitCtorArgs(raw_ostream &OS) const override {
        OS << getUpperName() << ", " << getUpperName() << "Size";
      }
  
      void writeDeclarations(raw_ostream &OS) const override {
        OS << "  unsigned " << ArgSizeName << ";\n";
        OS << "  " << getType() << " *" << ArgName << ";";
      }
  
      void writePCHReadDecls(raw_ostream &OS) const override {
        OS << "    unsigned " << getLowerName() << "Size = Record.readInt();\n";
        OS << "    SmallVector<" << getType() << ", 4> "
           << getLowerName() << ";\n";
        OS << "    " << getLowerName() << ".reserve(" << getLowerName()
           << "Size);\n";
  
        // If we can't store the values in the current type (if it's something
        // like StringRef), store them in a different type and convert the
        // container afterwards.
        std::string StorageType = std::string(getStorageType(getType()));
        std::string StorageName = std::string(getLowerName());
        if (StorageType != getType()) {
          StorageName += "Storage";
          OS << "    SmallVector<" << StorageType << ", 4> "
             << StorageName << ";\n";
          OS << "    " << StorageName << ".reserve(" << getLowerName()
             << "Size);\n";
        }
  
        OS << "    for (unsigned i = 0; i != " << getLowerName() << "Size; ++i)\n";
        std::string read = ReadPCHRecord(Type);
        OS << "      " << StorageName << ".push_back(" << read << ");\n";
  
        if (StorageType != getType()) {
          OS << "    for (unsigned i = 0; i != " << getLowerName() << "Size; ++i)\n";
          OS << "      " << getLowerName() << ".push_back("
             << StorageName << "[i]);\n";
        }
      }
  
      void writePCHReadArgs(raw_ostream &OS) const override {
        OS << getLowerName() << ".data(), " << getLowerName() << "Size";
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "    Record.push_back(SA->" << getLowerName() << "_size());\n";
        OS << "    for (auto &Val : SA->" << RangeName << "())\n";
        OS << "      " << WritePCHRecord(Type, "Val");
      }
  
      void writeValue(raw_ostream &OS) const override {
        OS << "\";\n";
        OS << "  for (const auto &Val : " << RangeName << "()) {\n"
           << "    DelimitAttributeArgument(OS, IsFirstArgument);\n";
        writeValueImpl(OS);
        OS << "  }\n";
        OS << "  OS << \"";
      }
  
      void writeDump(raw_ostream &OS) const override {
        OS << "    for (const auto &Val : SA->" << RangeName << "())\n";
        writeDumpImpl(OS);
      }
    };
  
    class VariadicParamIdxArgument : public VariadicArgument {
    public:
      VariadicParamIdxArgument(const Record &Arg, StringRef Attr)
          : VariadicArgument(Arg, Attr, "ParamIdx") {}
  
    public:
      void writeValueImpl(raw_ostream &OS) const override {
        OS << "    OS << Val.getSourceIndex();\n";
      }
  
      void writeDumpImpl(raw_ostream &OS) const override {
        OS << "      OS << \" \" << Val.getSourceIndex();\n";
      }
    };
  
    struct VariadicParamOrParamIdxArgument : public VariadicArgument {
      VariadicParamOrParamIdxArgument(const Record &Arg, StringRef Attr)
          : VariadicArgument(Arg, Attr, "int") {}
    };
  
    // Unique the enums, but maintain the original declaration ordering.
    std::vector<StringRef>
    uniqueEnumsInOrder(const std::vector<StringRef> &enums) {
      std::vector<StringRef> uniques;
      SmallDenseSet<StringRef, 8> unique_set;
      for (const auto &i : enums) {
        if (unique_set.insert(i).second)
          uniques.push_back(i);
      }
      return uniques;
    }
  
    class EnumArgument : public Argument {
      std::string type;
      std::vector<StringRef> values, enums, uniques;
  
    public:
      EnumArgument(const Record &Arg, StringRef Attr)
          : Argument(Arg, Attr), type(std::string(Arg.getValueAsString("Type"))),
            values(Arg.getValueAsListOfStrings("Values")),
            enums(Arg.getValueAsListOfStrings("Enums")),
            uniques(uniqueEnumsInOrder(enums)) {
        // FIXME: Emit a proper error
        assert(!uniques.empty());
      }
  
      bool isEnumArg() const override { return true; }
  
      void writeAccessors(raw_ostream &OS) const override {
        OS << "  " << type << " get" << getUpperName() << "() const {\n";
        OS << "    return " << getLowerName() << ";\n";
        OS << "  }";
      }
  
      void writeCloneArgs(raw_ostream &OS) const override {
        OS << getLowerName();
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        OS << "A->get" << getUpperName() << "()";
      }
      void writeCtorInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "(" << getUpperName() << ")";
      }
      void writeCtorDefaultInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "(" << type << "(0))";
      }
      void writeCtorParameters(raw_ostream &OS) const override {
        OS << type << " " << getUpperName();
      }
      void writeDeclarations(raw_ostream &OS) const override {
        auto i = uniques.cbegin(), e = uniques.cend();
        // The last one needs to not have a comma.
        --e;
  
        OS << "public:\n";
        OS << "  enum " << type << " {\n";
        for (; i != e; ++i)
          OS << "    " << *i << ",\n";
        OS << "    " << *e << "\n";
        OS << "  };\n";
        OS << "private:\n";
        OS << "  " << type << " " << getLowerName() << ";";
      }
  
      void writePCHReadDecls(raw_ostream &OS) const override {
        OS << "    " << getAttrName() << "Attr::" << type << " " << getLowerName()
           << "(static_cast<" << getAttrName() << "Attr::" << type
           << ">(Record.readInt()));\n";
      }
  
      void writePCHReadArgs(raw_ostream &OS) const override {
        OS << getLowerName();
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "Record.push_back(SA->get" << getUpperName() << "());\n";
      }
  
      void writeValue(raw_ostream &OS) const override {
        // FIXME: this isn't 100% correct -- some enum arguments require printing
        // as a string literal, while others require printing as an identifier.
        // Tablegen currently does not distinguish between the two forms.
        OS << "\\\"\" << " << getAttrName() << "Attr::Convert" << type << "ToStr(get"
           << getUpperName() << "()) << \"\\\"";
      }
  
      void writeDump(raw_ostream &OS) const override {
        OS << "    switch(SA->get" << getUpperName() << "()) {\n";
        for (const auto &I : uniques) {
          OS << "    case " << getAttrName() << "Attr::" << I << ":\n";
          OS << "      OS << \" " << I << "\";\n";
          OS << "      break;\n";
        }
        OS << "    }\n";
      }
  
      void writeConversion(raw_ostream &OS, bool Header) const {
        if (Header) {
          OS << "  static bool ConvertStrTo" << type << "(StringRef Val, " << type
             << " &Out);\n";
          OS << "  static const char *Convert" << type << "ToStr(" << type
             << " Val);\n";
          return;
        }
  
        OS << "bool " << getAttrName() << "Attr::ConvertStrTo" << type
           << "(StringRef Val, " << type << " &Out) {\n";
        OS << "  Optional<" << type << "> R = llvm::StringSwitch<Optional<";
        OS << type << ">>(Val)\n";
        for (size_t I = 0; I < enums.size(); ++I) {
          OS << "    .Case(\"" << values[I] << "\", ";
          OS << getAttrName() << "Attr::" << enums[I] << ")\n";
        }
        OS << "    .Default(Optional<" << type << ">());\n";
        OS << "  if (R) {\n";
        OS << "    Out = *R;\n      return true;\n    }\n";
        OS << "  return false;\n";
        OS << "}\n\n";
  
        // Mapping from enumeration values back to enumeration strings isn't
        // trivial because some enumeration values have multiple named
        // enumerators, such as type_visibility(internal) and
        // type_visibility(hidden) both mapping to TypeVisibilityAttr::Hidden.
        OS << "const char *" << getAttrName() << "Attr::Convert" << type
           << "ToStr(" << type << " Val) {\n"
           << "  switch(Val) {\n";
        SmallDenseSet<StringRef, 8> Uniques;
        for (size_t I = 0; I < enums.size(); ++I) {
          if (Uniques.insert(enums[I]).second)
            OS << "  case " << getAttrName() << "Attr::" << enums[I]
               << ": return \"" << values[I] << "\";\n";
        }
        OS << "  }\n"
           << "  llvm_unreachable(\"No enumerator with that value\");\n"
           << "}\n";
      }
    };
  
    class VariadicEnumArgument: public VariadicArgument {
      std::string type, QualifiedTypeName;
      std::vector<StringRef> values, enums, uniques;
  
    protected:
      void writeValueImpl(raw_ostream &OS) const override {
        // FIXME: this isn't 100% correct -- some enum arguments require printing
        // as a string literal, while others require printing as an identifier.
        // Tablegen currently does not distinguish between the two forms.
        OS << "    OS << \"\\\"\" << " << getAttrName() << "Attr::Convert" << type
           << "ToStr(Val)" << "<< \"\\\"\";\n";
      }
  
    public:
      VariadicEnumArgument(const Record &Arg, StringRef Attr)
          : VariadicArgument(Arg, Attr,
                             std::string(Arg.getValueAsString("Type"))),
            type(std::string(Arg.getValueAsString("Type"))),
            values(Arg.getValueAsListOfStrings("Values")),
            enums(Arg.getValueAsListOfStrings("Enums")),
            uniques(uniqueEnumsInOrder(enums)) {
        QualifiedTypeName = getAttrName().str() + "Attr::" + type;
  
        // FIXME: Emit a proper error
        assert(!uniques.empty());
      }
  
      bool isVariadicEnumArg() const override { return true; }
  
      void writeDeclarations(raw_ostream &OS) const override {
        auto i = uniques.cbegin(), e = uniques.cend();
        // The last one needs to not have a comma.
        --e;
  
        OS << "public:\n";
        OS << "  enum " << type << " {\n";
        for (; i != e; ++i)
          OS << "    " << *i << ",\n";
        OS << "    " << *e << "\n";
        OS << "  };\n";
        OS << "private:\n";
  
        VariadicArgument::writeDeclarations(OS);
      }
  
      void writeDump(raw_ostream &OS) const override {
        OS << "    for (" << getAttrName() << "Attr::" << getLowerName()
           << "_iterator I = SA->" << getLowerName() << "_begin(), E = SA->"
           << getLowerName() << "_end(); I != E; ++I) {\n";
        OS << "      switch(*I) {\n";
        for (const auto &UI : uniques) {
          OS << "    case " << getAttrName() << "Attr::" << UI << ":\n";
          OS << "      OS << \" " << UI << "\";\n";
          OS << "      break;\n";
        }
        OS << "      }\n";
        OS << "    }\n";
      }
  
      void writePCHReadDecls(raw_ostream &OS) const override {
        OS << "    unsigned " << getLowerName() << "Size = Record.readInt();\n";
        OS << "    SmallVector<" << QualifiedTypeName << ", 4> " << getLowerName()
           << ";\n";
        OS << "    " << getLowerName() << ".reserve(" << getLowerName()
           << "Size);\n";
        OS << "    for (unsigned i = " << getLowerName() << "Size; i; --i)\n";
        OS << "      " << getLowerName() << ".push_back(" << "static_cast<"
           << QualifiedTypeName << ">(Record.readInt()));\n";
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "    Record.push_back(SA->" << getLowerName() << "_size());\n";
        OS << "    for (" << getAttrName() << "Attr::" << getLowerName()
           << "_iterator i = SA->" << getLowerName() << "_begin(), e = SA->"
           << getLowerName() << "_end(); i != e; ++i)\n";
        OS << "      " << WritePCHRecord(QualifiedTypeName, "(*i)");
      }
  
      void writeConversion(raw_ostream &OS, bool Header) const {
        if (Header) {
          OS << "  static bool ConvertStrTo" << type << "(StringRef Val, " << type
             << " &Out);\n";
          OS << "  static const char *Convert" << type << "ToStr(" << type
             << " Val);\n";
          return;
        }
  
        OS << "bool " << getAttrName() << "Attr::ConvertStrTo" << type
           << "(StringRef Val, ";
        OS << type << " &Out) {\n";
        OS << "  Optional<" << type << "> R = llvm::StringSwitch<Optional<";
        OS << type << ">>(Val)\n";
        for (size_t I = 0; I < enums.size(); ++I) {
          OS << "    .Case(\"" << values[I] << "\", ";
          OS << getAttrName() << "Attr::" << enums[I] << ")\n";
        }
        OS << "    .Default(Optional<" << type << ">());\n";
        OS << "  if (R) {\n";
        OS << "    Out = *R;\n      return true;\n    }\n";
        OS << "  return false;\n";
        OS << "}\n\n";
  
        OS << "const char *" << getAttrName() << "Attr::Convert" << type
           << "ToStr(" << type << " Val) {\n"
           << "  switch(Val) {\n";
        SmallDenseSet<StringRef, 8> Uniques;
        for (size_t I = 0; I < enums.size(); ++I) {
          if (Uniques.insert(enums[I]).second)
            OS << "  case " << getAttrName() << "Attr::" << enums[I]
               << ": return \"" << values[I] << "\";\n";
        }
        OS << "  }\n"
           << "  llvm_unreachable(\"No enumerator with that value\");\n"
           << "}\n";
      }
    };
  
    class VersionArgument : public Argument {
    public:
      VersionArgument(const Record &Arg, StringRef Attr)
        : Argument(Arg, Attr)
      {}
  
      void writeAccessors(raw_ostream &OS) const override {
        OS << "  VersionTuple get" << getUpperName() << "() const {\n";
        OS << "    return " << getLowerName() << ";\n";
        OS << "  }\n";
        OS << "  void set" << getUpperName()
           << "(ASTContext &C, VersionTuple V) {\n";
        OS << "    " << getLowerName() << " = V;\n";
        OS << "  }";
      }
  
      void writeCloneArgs(raw_ostream &OS) const override {
        OS << "get" << getUpperName() << "()";
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        OS << "A->get" << getUpperName() << "()";
      }
  
      void writeCtorInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "(" << getUpperName() << ")";
      }
  
      void writeCtorDefaultInitializers(raw_ostream &OS) const override {
        OS << getLowerName() << "()";
      }
  
      void writeCtorParameters(raw_ostream &OS) const override {
        OS << "VersionTuple " << getUpperName();
      }
  
      void writeDeclarations(raw_ostream &OS) const override {
        OS << "VersionTuple " << getLowerName() << ";\n";
      }
  
      void writePCHReadDecls(raw_ostream &OS) const override {
        OS << "    VersionTuple " << getLowerName()
           << "= Record.readVersionTuple();\n";
      }
  
      void writePCHReadArgs(raw_ostream &OS) const override {
        OS << getLowerName();
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "    Record.AddVersionTuple(SA->get" << getUpperName() << "());\n";
      }
  
      void writeValue(raw_ostream &OS) const override {
        OS << getLowerName() << "=\" << get" << getUpperName() << "() << \"";
      }
  
      void writeDump(raw_ostream &OS) const override {
        OS << "    OS << \" \" << SA->get" << getUpperName() << "();\n";
      }
    };
  
    class ExprArgument : public SimpleArgument {
    public:
      ExprArgument(const Record &Arg, StringRef Attr)
        : SimpleArgument(Arg, Attr, "Expr *")
      {}
  
      void writeASTVisitorTraversal(raw_ostream &OS) const override {
        OS << "  if (!"
           << "getDerived().TraverseStmt(A->get" << getUpperName() << "()))\n";
        OS << "    return false;\n";
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        OS << "tempInst" << getUpperName();
      }
  
      void writeTemplateInstantiation(raw_ostream &OS) const override {
        OS << "      " << getType() << " tempInst" << getUpperName() << ";\n";
        OS << "      {\n";
        OS << "        EnterExpressionEvaluationContext "
           << "Unevaluated(S, Sema::ExpressionEvaluationContext::Unevaluated);\n";
        OS << "        ExprResult " << "Result = S.SubstExpr("
           << "A->get" << getUpperName() << "(), TemplateArgs);\n";
        OS << "        if (Result.isInvalid())\n";
        OS << "          return nullptr;\n";
        OS << "        tempInst" << getUpperName() << " = Result.get();\n";
        OS << "      }\n";
      }
  
      void writeDump(raw_ostream &OS) const override {}
  
      void writeDumpChildren(raw_ostream &OS) const override {
        OS << "    Visit(SA->get" << getUpperName() << "());\n";
      }
  
      void writeHasChildren(raw_ostream &OS) const override { OS << "true"; }
    };
  
    class VariadicExprArgument : public VariadicArgument {
    public:
      VariadicExprArgument(const Record &Arg, StringRef Attr)
        : VariadicArgument(Arg, Attr, "Expr *")
      {}
  
      void writeASTVisitorTraversal(raw_ostream &OS) const override {
        OS << "  {\n";
        OS << "    " << getType() << " *I = A->" << getLowerName()
           << "_begin();\n";
        OS << "    " << getType() << " *E = A->" << getLowerName()
           << "_end();\n";
        OS << "    for (; I != E; ++I) {\n";
        OS << "      if (!getDerived().TraverseStmt(*I))\n";
        OS << "        return false;\n";
        OS << "    }\n";
        OS << "  }\n";
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        OS << "tempInst" << getUpperName() << ", "
           << "A->" << getLowerName() << "_size()";
      }
  
      void writeTemplateInstantiation(raw_ostream &OS) const override {
        OS << "      auto *tempInst" << getUpperName()
           << " = new (C, 16) " << getType()
           << "[A->" << getLowerName() << "_size()];\n";
        OS << "      {\n";
        OS << "        EnterExpressionEvaluationContext "
           << "Unevaluated(S, Sema::ExpressionEvaluationContext::Unevaluated);\n";
        OS << "        " << getType() << " *TI = tempInst" << getUpperName()
           << ";\n";
        OS << "        " << getType() << " *I = A->" << getLowerName()
           << "_begin();\n";
        OS << "        " << getType() << " *E = A->" << getLowerName()
           << "_end();\n";
        OS << "        for (; I != E; ++I, ++TI) {\n";
        OS << "          ExprResult Result = S.SubstExpr(*I, TemplateArgs);\n";
        OS << "          if (Result.isInvalid())\n";
        OS << "            return nullptr;\n";
        OS << "          *TI = Result.get();\n";
        OS << "        }\n";
        OS << "      }\n";
      }
  
      void writeDump(raw_ostream &OS) const override {}
  
      void writeDumpChildren(raw_ostream &OS) const override {
        OS << "    for (" << getAttrName() << "Attr::" << getLowerName()
           << "_iterator I = SA->" << getLowerName() << "_begin(), E = SA->"
           << getLowerName() << "_end(); I != E; ++I)\n";
        OS << "      Visit(*I);\n";
      }
  
      void writeHasChildren(raw_ostream &OS) const override {
        OS << "SA->" << getLowerName() << "_begin() != "
           << "SA->" << getLowerName() << "_end()";
      }
    };
  
    class VariadicIdentifierArgument : public VariadicArgument {
    public:
      VariadicIdentifierArgument(const Record &Arg, StringRef Attr)
        : VariadicArgument(Arg, Attr, "IdentifierInfo *")
      {}
    };
  
    class VariadicStringArgument : public VariadicArgument {
    public:
      VariadicStringArgument(const Record &Arg, StringRef Attr)
        : VariadicArgument(Arg, Attr, "StringRef")
      {}
  
      void writeCtorBody(raw_ostream &OS) const override {
        OS << "  for (size_t I = 0, E = " << getArgSizeName() << "; I != E;\n"
              "       ++I) {\n"
              "    StringRef Ref = " << getUpperName() << "[I];\n"
              "    if (!Ref.empty()) {\n"
              "      char *Mem = new (Ctx, 1) char[Ref.size()];\n"
              "      std::memcpy(Mem, Ref.data(), Ref.size());\n"
              "      " << getArgName() << "[I] = StringRef(Mem, Ref.size());\n"
              "    }\n"
              "  }\n";
      }
  
      void writeValueImpl(raw_ostream &OS) const override {
        OS << "    OS << \"\\\"\" << Val << \"\\\"\";\n";
      }
    };
  
    class TypeArgument : public SimpleArgument {
    public:
      TypeArgument(const Record &Arg, StringRef Attr)
        : SimpleArgument(Arg, Attr, "TypeSourceInfo *")
      {}
  
      void writeAccessors(raw_ostream &OS) const override {
        OS << "  QualType get" << getUpperName() << "() const {\n";
        OS << "    return " << getLowerName() << "->getType();\n";
        OS << "  }";
        OS << "  " << getType() << " get" << getUpperName() << "Loc() const {\n";
        OS << "    return " << getLowerName() << ";\n";
        OS << "  }";
      }
  
      void writeASTVisitorTraversal(raw_ostream &OS) const override {
        OS << "  if (auto *TSI = A->get" << getUpperName() << "Loc())\n";
        OS << "    if (!getDerived().TraverseTypeLoc(TSI->getTypeLoc()))\n";
        OS << "      return false;\n";
      }
  
      void writeTemplateInstantiation(raw_ostream &OS) const override {
        OS << "      " << getType() << " tempInst" << getUpperName() << " =\n";
        OS << "        S.SubstType(A->get" << getUpperName() << "Loc(), "
           << "TemplateArgs, A->getLoc(), A->getAttrName());\n";
        OS << "      if (!tempInst" << getUpperName() << ")\n";
        OS << "        return nullptr;\n";
      }
  
      void writeTemplateInstantiationArgs(raw_ostream &OS) const override {
        OS << "tempInst" << getUpperName();
      }
  
      void writePCHWrite(raw_ostream &OS) const override {
        OS << "    "
           << WritePCHRecord(getType(),
                             "SA->get" + std::string(getUpperName()) + "Loc()");
      }
    };
  
  } // end anonymous namespace
  
  static std::unique_ptr<Argument>
  createArgument(const Record &Arg, StringRef Attr,
                 const Record *Search = nullptr) {
    if (!Search)
      Search = &Arg;
  
    std::unique_ptr<Argument> Ptr;
    llvm::StringRef ArgName = Search->getName();
  
    if (ArgName == "AlignedArgument")
      Ptr = std::make_unique<AlignedArgument>(Arg, Attr);
    else if (ArgName == "EnumArgument")
      Ptr = std::make_unique<EnumArgument>(Arg, Attr);
    else if (ArgName == "ExprArgument")
      Ptr = std::make_unique<ExprArgument>(Arg, Attr);
    else if (ArgName == "DeclArgument")
      Ptr = std::make_unique<SimpleArgument>(
          Arg, Attr, (Arg.getValueAsDef("Kind")->getName() + "Decl *").str());
    else if (ArgName == "IdentifierArgument")
      Ptr = std::make_unique<SimpleArgument>(Arg, Attr, "IdentifierInfo *");
    else if (ArgName == "DefaultBoolArgument")
      Ptr = std::make_unique<DefaultSimpleArgument>(
          Arg, Attr, "bool", Arg.getValueAsBit("Default"));
    else if (ArgName == "BoolArgument")
      Ptr = std::make_unique<SimpleArgument>(Arg, Attr, "bool");
    else if (ArgName == "DefaultIntArgument")
      Ptr = std::make_unique<DefaultSimpleArgument>(
          Arg, Attr, "int", Arg.getValueAsInt("Default"));
    else if (ArgName == "IntArgument")
      Ptr = std::make_unique<SimpleArgument>(Arg, Attr, "int");
    else if (ArgName == "StringArgument")
      Ptr = std::make_unique<StringArgument>(Arg, Attr);
    else if (ArgName == "TypeArgument")
      Ptr = std::make_unique<TypeArgument>(Arg, Attr);
    else if (ArgName == "UnsignedArgument")
      Ptr = std::make_unique<SimpleArgument>(Arg, Attr, "unsigned");
    else if (ArgName == "DefaultUnsignedArgument")
      Ptr = std::make_unique<DefaultSimpleArgument>(Arg, Attr, "unsigned",
                                                    Arg.getValueAsInt("Default"));
    else if (ArgName == "VariadicUnsignedArgument")
      Ptr = std::make_unique<VariadicArgument>(Arg, Attr, "unsigned");
    else if (ArgName == "VariadicStringArgument")
      Ptr = std::make_unique<VariadicStringArgument>(Arg, Attr);
    else if (ArgName == "VariadicEnumArgument")
      Ptr = std::make_unique<VariadicEnumArgument>(Arg, Attr);
    else if (ArgName == "VariadicExprArgument")
      Ptr = std::make_unique<VariadicExprArgument>(Arg, Attr);
    else if (ArgName == "VariadicParamIdxArgument")
      Ptr = std::make_unique<VariadicParamIdxArgument>(Arg, Attr);
    else if (ArgName == "VariadicParamOrParamIdxArgument")
      Ptr = std::make_unique<VariadicParamOrParamIdxArgument>(Arg, Attr);
    else if (ArgName == "ParamIdxArgument")
      Ptr = std::make_unique<SimpleArgument>(Arg, Attr, "ParamIdx");
    else if (ArgName == "VariadicIdentifierArgument")
      Ptr = std::make_unique<VariadicIdentifierArgument>(Arg, Attr);
    else if (ArgName == "VersionArgument")
      Ptr = std::make_unique<VersionArgument>(Arg, Attr);
    else if (ArgName == "OMPTraitInfoArgument")
      Ptr = std::make_unique<SimpleArgument>(Arg, Attr, "OMPTraitInfo *");
  
    if (!Ptr) {
      // Search in reverse order so that the most-derived type is handled first.
      ArrayRef<std::pair<Record*, SMRange>> Bases = Search->getSuperClasses();
      for (const auto &Base : llvm::reverse(Bases)) {
        if ((Ptr = createArgument(Arg, Attr, Base.first)))
          break;
      }
    }
  
    if (Ptr && Arg.getValueAsBit("Optional"))
      Ptr->setOptional(true);
  
    if (Ptr && Arg.getValueAsBit("Fake"))
      Ptr->setFake(true);
  
    return Ptr;
  }
  
  static void writeAvailabilityValue(raw_ostream &OS) {
    OS << "\" << getPlatform()->getName();\n"
       << "  if (getStrict()) OS << \", strict\";\n"
       << "  if (!getIntroduced().empty()) OS << \", introduced=\" << getIntroduced();\n"
       << "  if (!getDeprecated().empty()) OS << \", deprecated=\" << getDeprecated();\n"
       << "  if (!getObsoleted().empty()) OS << \", obsoleted=\" << getObsoleted();\n"
       << "  if (getUnavailable()) OS << \", unavailable\";\n"
       << "  OS << \"";
  }
  
  static void writeDeprecatedAttrValue(raw_ostream &OS, std::string &Variety) {
    OS << "\\\"\" << getMessage() << \"\\\"\";\n";
    // Only GNU deprecated has an optional fixit argument at the second position.
    if (Variety == "GNU")
       OS << "    if (!getReplacement().empty()) OS << \", \\\"\""
             " << getReplacement() << \"\\\"\";\n";
    OS << "    OS << \"";
  }
  
  static void writeGetSpellingFunction(const Record &R, raw_ostream &OS) {
    std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(R);
  
    OS << "const char *" << R.getName() << "Attr::getSpelling() const {\n";
    if (Spellings.empty()) {
      OS << "  return \"(No spelling)\";\n}\n\n";
      return;
    }
  
    OS << "  switch (getAttributeSpellingListIndex()) {\n"
          "  default:\n"
          "    llvm_unreachable(\"Unknown attribute spelling!\");\n"
          "    return \"(No spelling)\";\n";
  
    for (unsigned I = 0; I < Spellings.size(); ++I)
      OS << "  case " << I << ":\n"
            "    return \"" << Spellings[I].name() << "\";\n";
    // End of the switch statement.
    OS << "  }\n";
    // End of the getSpelling function.
    OS << "}\n\n";
  }
  
  static void
  writePrettyPrintFunction(const Record &R,
                           const std::vector<std::unique_ptr<Argument>> &Args,
                           raw_ostream &OS) {
    std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(R);
  
    OS << "void " << R.getName() << "Attr::printPretty("
      << "raw_ostream &OS, const PrintingPolicy &Policy) const {\n";
  
    if (Spellings.empty()) {
      OS << "}\n\n";
      return;
    }
  
    OS << "  bool IsFirstArgument = true; (void)IsFirstArgument;\n"
       << "  unsigned TrailingOmittedArgs = 0; (void)TrailingOmittedArgs;\n"
       << "  switch (getAttributeSpellingListIndex()) {\n"
       << "  default:\n"
       << "    llvm_unreachable(\"Unknown attribute spelling!\");\n"
       << "    break;\n";
  
    for (unsigned I = 0; I < Spellings.size(); ++ I) {
      llvm::SmallString<16> Prefix;
      llvm::SmallString<8> Suffix;
      // The actual spelling of the name and namespace (if applicable)
      // of an attribute without considering prefix and suffix.
      llvm::SmallString<64> Spelling;
      std::string Name = Spellings[I].name();
      std::string Variety = Spellings[I].variety();
  
      if (Variety == "GNU") {
        Prefix = " __attribute__((";
        Suffix = "))";
      } else if (Variety == "CXX11" || Variety == "C2x") {
        Prefix = " [[";
        Suffix = "]]";
        std::string Namespace = Spellings[I].nameSpace();
        if (!Namespace.empty()) {
          Spelling += Namespace;
          Spelling += "::";
        }
      } else if (Variety == "Declspec") {
        Prefix = " __declspec(";
        Suffix = ")";
      } else if (Variety == "Microsoft") {
        Prefix = "[";
        Suffix = "]";
      } else if (Variety == "Keyword") {
        Prefix = " ";
        Suffix = "";
      } else if (Variety == "Pragma") {
        Prefix = "#pragma ";
        Suffix = "\n";
        std::string Namespace = Spellings[I].nameSpace();
        if (!Namespace.empty()) {
          Spelling += Namespace;
          Spelling += " ";
        }
      } else {
        llvm_unreachable("Unknown attribute syntax variety!");
      }
  
      Spelling += Name;
  
      OS << "  case " << I << " : {\n"
         << "    OS << \"" << Prefix << Spelling << "\";\n";
  
      if (Variety == "Pragma") {
        OS << "    printPrettyPragma(OS, Policy);\n";
        OS << "    OS << \"\\n\";";
        OS << "    break;\n";
        OS << "  }\n";
        continue;
      }
  
      if (Spelling == "availability") {
        OS << "    OS << \"(";
        writeAvailabilityValue(OS);
        OS << ")\";\n";
      } else if (Spelling == "deprecated" || Spelling == "gnu::deprecated") {
        OS << "    OS << \"(";
        writeDeprecatedAttrValue(OS, Variety);
        OS << ")\";\n";
      } else {
        // To avoid printing parentheses around an empty argument list or
        // printing spurious commas at the end of an argument list, we need to
        // determine where the last provided non-fake argument is.
        unsigned NonFakeArgs = 0;
        bool FoundNonOptArg = false;
        for (const auto &arg : llvm::reverse(Args)) {
          if (arg->isFake())
            continue;
          ++NonFakeArgs;
          if (FoundNonOptArg)
            continue;
          // FIXME: arg->getIsOmitted() == "false" means we haven't implemented
          // any way to detect whether the argument was omitted.
          if (!arg->isOptional() || arg->getIsOmitted() == "false") {
            FoundNonOptArg = true;
            continue;
          }
          OS << "    if (" << arg->getIsOmitted() << ")\n"
             << "      ++TrailingOmittedArgs;\n";
        }
        unsigned ArgIndex = 0;
        for (const auto &arg : Args) {
          if (arg->isFake())
            continue;
          std::string IsOmitted = arg->getIsOmitted();
          if (arg->isOptional() && IsOmitted != "false")
            OS << "    if (!(" << IsOmitted << ")) {\n";
          // Variadic arguments print their own leading comma.
          if (!arg->isVariadic())
            OS << "    DelimitAttributeArgument(OS, IsFirstArgument);\n";
          OS << "    OS << \"";
          arg->writeValue(OS);
          OS << "\";\n";
          if (arg->isOptional() && IsOmitted != "false")
            OS << "    }\n";
          ++ArgIndex;
        }
        if (ArgIndex != 0)
          OS << "    if (!IsFirstArgument)\n"
             << "      OS << \")\";\n";
      }
      OS << "    OS << \"" << Suffix << "\";\n"
         << "    break;\n"
         << "  }\n";
    }
  
    // End of the switch statement.
    OS << "}\n";
    // End of the print function.
    OS << "}\n\n";
  }
  
  /// Return the index of a spelling in a spelling list.
  static unsigned
  getSpellingListIndex(const std::vector<FlattenedSpelling> &SpellingList,
                       const FlattenedSpelling &Spelling) {
    assert(!SpellingList.empty() && "Spelling list is empty!");
  
    for (unsigned Index = 0; Index < SpellingList.size(); ++Index) {
      const FlattenedSpelling &S = SpellingList[Index];
      if (S.variety() != Spelling.variety())
        continue;
      if (S.nameSpace() != Spelling.nameSpace())
        continue;
      if (S.name() != Spelling.name())
        continue;
  
      return Index;
    }
  
    llvm_unreachable("Unknown spelling!");
  }
  
  static void writeAttrAccessorDefinition(const Record &R, raw_ostream &OS) {
    std::vector<Record*> Accessors = R.getValueAsListOfDefs("Accessors");
    if (Accessors.empty())
      return;
  
    const std::vector<FlattenedSpelling> SpellingList = GetFlattenedSpellings(R);
    assert(!SpellingList.empty() &&
           "Attribute with empty spelling list can't have accessors!");
    for (const auto *Accessor : Accessors) {
      const StringRef Name = Accessor->getValueAsString("Name");
      std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(*Accessor);
  
      OS << "  bool " << Name
         << "() const { return getAttributeSpellingListIndex() == ";
      for (unsigned Index = 0; Index < Spellings.size(); ++Index) {
        OS << getSpellingListIndex(SpellingList, Spellings[Index]);
        if (Index != Spellings.size() - 1)
          OS << " ||\n    getAttributeSpellingListIndex() == ";
        else
          OS << "; }\n";
      }
    }
  }
  
  static bool
  SpellingNamesAreCommon(const std::vector<FlattenedSpelling>& Spellings) {
    assert(!Spellings.empty() && "An empty list of spellings was provided");
    std::string FirstName =
        std::string(NormalizeNameForSpellingComparison(Spellings.front().name()));
    for (const auto &Spelling :
         llvm::make_range(std::next(Spellings.begin()), Spellings.end())) {
      std::string Name =
          std::string(NormalizeNameForSpellingComparison(Spelling.name()));
      if (Name != FirstName)
        return false;
    }
    return true;
  }
  
  typedef std::map<unsigned, std::string> SemanticSpellingMap;
  static std::string
  CreateSemanticSpellings(const std::vector<FlattenedSpelling> &Spellings,
                          SemanticSpellingMap &Map) {
    // The enumerants are automatically generated based on the variety,
    // namespace (if present) and name for each attribute spelling. However,
    // care is taken to avoid trampling on the reserved namespace due to
    // underscores.
    std::string Ret("  enum Spelling {\n");
    std::set<std::string> Uniques;
    unsigned Idx = 0;
  
    // If we have a need to have this many spellings we likely need to add an
    // extra bit to the SpellingIndex in AttributeCommonInfo, then increase the
    // value of SpellingNotCalculated there and here.
    assert(Spellings.size() < 15 &&
           "Too many spellings, would step on SpellingNotCalculated in "
           "AttributeCommonInfo");
    for (auto I = Spellings.begin(), E = Spellings.end(); I != E; ++I, ++Idx) {
      const FlattenedSpelling &S = *I;
      const std::string &Variety = S.variety();
      const std::string &Spelling = S.name();
      const std::string &Namespace = S.nameSpace();
      std::string EnumName;
  
      EnumName += (Variety + "_");
      if (!Namespace.empty())
        EnumName += (NormalizeNameForSpellingComparison(Namespace).str() +
        "_");
      EnumName += NormalizeNameForSpellingComparison(Spelling);
  
      // Even if the name is not unique, this spelling index corresponds to a
      // particular enumerant name that we've calculated.
      Map[Idx] = EnumName;
  
      // Since we have been stripping underscores to avoid trampling on the
      // reserved namespace, we may have inadvertently created duplicate
      // enumerant names. These duplicates are not considered part of the
      // semantic spelling, and can be elided.
      if (Uniques.find(EnumName) != Uniques.end())
        continue;
  
      Uniques.insert(EnumName);
      if (I != Spellings.begin())
        Ret += ",\n";
      // Duplicate spellings are not considered part of the semantic spelling
      // enumeration, but the spelling index and semantic spelling values are
      // meant to be equivalent, so we must specify a concrete value for each
      // enumerator.
      Ret += "    " + EnumName + " = " + llvm::utostr(Idx);
    }
    Ret += ",\n  SpellingNotCalculated = 15\n";
    Ret += "\n  };\n\n";
    return Ret;
  }
  
  void WriteSemanticSpellingSwitch(const std::string &VarName,
                                   const SemanticSpellingMap &Map,
                                   raw_ostream &OS) {
    OS << "  switch (" << VarName << ") {\n    default: "
      << "llvm_unreachable(\"Unknown spelling list index\");\n";
    for (const auto &I : Map)
      OS << "    case " << I.first << ": return " << I.second << ";\n";
    OS << "  }\n";
  }
  
  // Emits the LateParsed property for attributes.
  static void emitClangAttrLateParsedList(RecordKeeper &Records, raw_ostream &OS) {
    OS << "#if defined(CLANG_ATTR_LATE_PARSED_LIST)\n";
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr");
  
    for (const auto *Attr : Attrs) {
      bool LateParsed = Attr->getValueAsBit("LateParsed");
  
      if (LateParsed) {
        std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(*Attr);
  
        // FIXME: Handle non-GNU attributes
        for (const auto &I : Spellings) {
          if (I.variety() != "GNU")
            continue;
          OS << ".Case(\"" << I.name() << "\", " << LateParsed << ")\n";
        }
      }
    }
    OS << "#endif // CLANG_ATTR_LATE_PARSED_LIST\n\n";
  }
  
  static bool hasGNUorCXX11Spelling(const Record &Attribute) {
    std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(Attribute);
    for (const auto &I : Spellings) {
      if (I.variety() == "GNU" || I.variety() == "CXX11")
        return true;
    }
    return false;
  }
  
  namespace {
  
  struct AttributeSubjectMatchRule {
    const Record *MetaSubject;
    const Record *Constraint;
  
    AttributeSubjectMatchRule(const Record *MetaSubject, const Record *Constraint)
        : MetaSubject(MetaSubject), Constraint(Constraint) {
      assert(MetaSubject && "Missing subject");
    }
  
    bool isSubRule() const { return Constraint != nullptr; }
  
    std::vector<Record *> getSubjects() const {
      return (Constraint ? Constraint : MetaSubject)
          ->getValueAsListOfDefs("Subjects");
    }
  
    std::vector<Record *> getLangOpts() const {
      if (Constraint) {
        // Lookup the options in the sub-rule first, in case the sub-rule
        // overrides the rules options.
        std::vector<Record *> Opts = Constraint->getValueAsListOfDefs("LangOpts");
        if (!Opts.empty())
          return Opts;
      }
      return MetaSubject->getValueAsListOfDefs("LangOpts");
    }
  
    // Abstract rules are used only for sub-rules
    bool isAbstractRule() const { return getSubjects().empty(); }
  
    StringRef getName() const {
      return (Constraint ? Constraint : MetaSubject)->getValueAsString("Name");
    }
  
    bool isNegatedSubRule() const {
      assert(isSubRule() && "Not a sub-rule");
      return Constraint->getValueAsBit("Negated");
    }
  
    std::string getSpelling() const {
      std::string Result = std::string(MetaSubject->getValueAsString("Name"));
      if (isSubRule()) {
        Result += '(';
        if (isNegatedSubRule())
          Result += "unless(";
        Result += getName();
        if (isNegatedSubRule())
          Result += ')';
        Result += ')';
      }
      return Result;
    }
  
    std::string getEnumValueName() const {
      SmallString<128> Result;
      Result += "SubjectMatchRule_";
      Result += MetaSubject->getValueAsString("Name");
      if (isSubRule()) {
        Result += "_";
        if (isNegatedSubRule())
          Result += "not_";
        Result += Constraint->getValueAsString("Name");
      }
      if (isAbstractRule())
        Result += "_abstract";
      return std::string(Result.str());
    }
  
    std::string getEnumValue() const { return "attr::" + getEnumValueName(); }
  
    static const char *EnumName;
  };
  
  const char *AttributeSubjectMatchRule::EnumName = "attr::SubjectMatchRule";
  
  struct PragmaClangAttributeSupport {
    std::vector<AttributeSubjectMatchRule> Rules;
  
    class RuleOrAggregateRuleSet {
      std::vector<AttributeSubjectMatchRule> Rules;
      bool IsRule;
      RuleOrAggregateRuleSet(ArrayRef<AttributeSubjectMatchRule> Rules,
                             bool IsRule)
          : Rules(Rules), IsRule(IsRule) {}
  
    public:
      bool isRule() const { return IsRule; }
  
      const AttributeSubjectMatchRule &getRule() const {
        assert(IsRule && "not a rule!");
        return Rules[0];
      }
  
      ArrayRef<AttributeSubjectMatchRule> getAggregateRuleSet() const {
        return Rules;
      }
  
      static RuleOrAggregateRuleSet
      getRule(const AttributeSubjectMatchRule &Rule) {
        return RuleOrAggregateRuleSet(Rule, /*IsRule=*/true);
      }
      static RuleOrAggregateRuleSet
      getAggregateRuleSet(ArrayRef<AttributeSubjectMatchRule> Rules) {
        return RuleOrAggregateRuleSet(Rules, /*IsRule=*/false);
      }
    };
    llvm::DenseMap<const Record *, RuleOrAggregateRuleSet> SubjectsToRules;
  
    PragmaClangAttributeSupport(RecordKeeper &Records);
  
    bool isAttributedSupported(const Record &Attribute);
  
    void emitMatchRuleList(raw_ostream &OS);
  
    void generateStrictConformsTo(const Record &Attr, raw_ostream &OS);
  
    void generateParsingHelpers(raw_ostream &OS);
  };
  
  } // end anonymous namespace
  
  static bool isSupportedPragmaClangAttributeSubject(const Record &Subject) {
    // FIXME: #pragma clang attribute does not currently support statement
    // attributes, so test whether the subject is one that appertains to a
    // declaration node. However, it may be reasonable for support for statement
    // attributes to be added.
    if (Subject.isSubClassOf("DeclNode") || Subject.isSubClassOf("DeclBase") ||
        Subject.getName() == "DeclBase")
      return true;
  
    if (Subject.isSubClassOf("SubsetSubject"))
      return isSupportedPragmaClangAttributeSubject(
          *Subject.getValueAsDef("Base"));
  
    return false;
  }
  
  static bool doesDeclDeriveFrom(const Record *D, const Record *Base) {
    const Record *CurrentBase = D->getValueAsOptionalDef(BaseFieldName);
    if (!CurrentBase)
      return false;
    if (CurrentBase == Base)
      return true;
    return doesDeclDeriveFrom(CurrentBase, Base);
  }
  
  PragmaClangAttributeSupport::PragmaClangAttributeSupport(
      RecordKeeper &Records) {
    std::vector<Record *> MetaSubjects =
        Records.getAllDerivedDefinitions("AttrSubjectMatcherRule");
    auto MapFromSubjectsToRules = [this](const Record *SubjectContainer,
                                         const Record *MetaSubject,
                                         const Record *Constraint) {
      Rules.emplace_back(MetaSubject, Constraint);
      std::vector<Record *> ApplicableSubjects =
          SubjectContainer->getValueAsListOfDefs("Subjects");
      for (const auto *Subject : ApplicableSubjects) {
        bool Inserted =
            SubjectsToRules
                .try_emplace(Subject, RuleOrAggregateRuleSet::getRule(
                                          AttributeSubjectMatchRule(MetaSubject,
                                                                    Constraint)))
                .second;
        if (!Inserted) {
          PrintFatalError("Attribute subject match rules should not represent"
                          "same attribute subjects.");
        }
      }
    };
    for (const auto *MetaSubject : MetaSubjects) {
      MapFromSubjectsToRules(MetaSubject, MetaSubject, /*Constraints=*/nullptr);
      std::vector<Record *> Constraints =
          MetaSubject->getValueAsListOfDefs("Constraints");
      for (const auto *Constraint : Constraints)
        MapFromSubjectsToRules(Constraint, MetaSubject, Constraint);
    }
  
    std::vector<Record *> Aggregates =
        Records.getAllDerivedDefinitions("AttrSubjectMatcherAggregateRule");
    std::vector<Record *> DeclNodes =
      Records.getAllDerivedDefinitions(DeclNodeClassName);
    for (const auto *Aggregate : Aggregates) {
      Record *SubjectDecl = Aggregate->getValueAsDef("Subject");
  
      // Gather sub-classes of the aggregate subject that act as attribute
      // subject rules.
      std::vector<AttributeSubjectMatchRule> Rules;
      for (const auto *D : DeclNodes) {
        if (doesDeclDeriveFrom(D, SubjectDecl)) {
          auto It = SubjectsToRules.find(D);
          if (It == SubjectsToRules.end())
            continue;
          if (!It->second.isRule() || It->second.getRule().isSubRule())
            continue; // Assume that the rule will be included as well.
          Rules.push_back(It->second.getRule());
        }
      }
  
      bool Inserted =
          SubjectsToRules
              .try_emplace(SubjectDecl,
                           RuleOrAggregateRuleSet::getAggregateRuleSet(Rules))
              .second;
      if (!Inserted) {
        PrintFatalError("Attribute subject match rules should not represent"
                        "same attribute subjects.");
      }
    }
  }
  
  static PragmaClangAttributeSupport &
  getPragmaAttributeSupport(RecordKeeper &Records) {
    static PragmaClangAttributeSupport Instance(Records);
    return Instance;
  }
  
  void PragmaClangAttributeSupport::emitMatchRuleList(raw_ostream &OS) {
    OS << "#ifndef ATTR_MATCH_SUB_RULE\n";
    OS << "#define ATTR_MATCH_SUB_RULE(Value, Spelling, IsAbstract, Parent, "
          "IsNegated) "
       << "ATTR_MATCH_RULE(Value, Spelling, IsAbstract)\n";
    OS << "#endif\n";
    for (const auto &Rule : Rules) {
      OS << (Rule.isSubRule() ? "ATTR_MATCH_SUB_RULE" : "ATTR_MATCH_RULE") << '(';
      OS << Rule.getEnumValueName() << ", \"" << Rule.getSpelling() << "\", "
         << Rule.isAbstractRule();
      if (Rule.isSubRule())
        OS << ", "
           << AttributeSubjectMatchRule(Rule.MetaSubject, nullptr).getEnumValue()
           << ", " << Rule.isNegatedSubRule();
      OS << ")\n";
    }
    OS << "#undef ATTR_MATCH_SUB_RULE\n";
  }
  
  bool PragmaClangAttributeSupport::isAttributedSupported(
      const Record &Attribute) {
    // If the attribute explicitly specified whether to support #pragma clang
    // attribute, use that setting.
    bool Unset;
    bool SpecifiedResult =
      Attribute.getValueAsBitOrUnset("PragmaAttributeSupport", Unset);
    if (!Unset)
      return SpecifiedResult;
  
    // Opt-out rules:
    // An attribute requires delayed parsing (LateParsed is on)
    if (Attribute.getValueAsBit("LateParsed"))
      return false;
    // An attribute has no GNU/CXX11 spelling
    if (!hasGNUorCXX11Spelling(Attribute))
      return false;
    // An attribute subject list has a subject that isn't covered by one of the
    // subject match rules or has no subjects at all.
    if (Attribute.isValueUnset("Subjects"))
      return false;
    const Record *SubjectObj = Attribute.getValueAsDef("Subjects");
    std::vector<Record *> Subjects = SubjectObj->getValueAsListOfDefs("Subjects");
    bool HasAtLeastOneValidSubject = false;
    for (const auto *Subject : Subjects) {
      if (!isSupportedPragmaClangAttributeSubject(*Subject))
        continue;
      if (SubjectsToRules.find(Subject) == SubjectsToRules.end())
        return false;
      HasAtLeastOneValidSubject = true;
    }
    return HasAtLeastOneValidSubject;
  }
  
  static std::string GenerateTestExpression(ArrayRef<Record *> LangOpts,
                                            bool IsAttrAccepted) {
    std::string Test;
  
    for (auto *E : LangOpts) {
      bool SilentlyIgnore = E->getValueAsBit("SilentlyIgnore");
      if (SilentlyIgnore == IsAttrAccepted)
        continue;
  
      if (!Test.empty())
        Test += " || ";
  
      const StringRef Code = E->getValueAsString("CustomCode");
      if (!Code.empty()) {
        Test += "(";
        Test += Code;
        Test += ")";
        if (!E->getValueAsString("Name").empty()) {
          PrintWarning(
              E->getLoc(),
              "non-empty 'Name' field ignored because 'CustomCode' was supplied");
        }
      } else {
        if (!IsAttrAccepted && SilentlyIgnore)
          Test += "!";
        Test += "LangOpts.";
        Test += E->getValueAsString("Name");
      }
    }
  
    if (Test.empty())
      return "true";
  
    return Test;
  }
  
  void
  PragmaClangAttributeSupport::generateStrictConformsTo(const Record &Attr,
                                                        raw_ostream &OS) {
    if (!isAttributedSupported(Attr) || Attr.isValueUnset("Subjects"))
      return;
    // Generate a function that constructs a set of matching rules that describe
    // to which declarations the attribute should apply to.
    OS << "void getPragmaAttributeMatchRules("
       << "llvm::SmallVectorImpl<std::pair<"
       << AttributeSubjectMatchRule::EnumName
       << ", bool>> &MatchRules, const LangOptions &LangOpts) const override {\n";
    const Record *SubjectObj = Attr.getValueAsDef("Subjects");
    std::vector<Record *> Subjects = SubjectObj->getValueAsListOfDefs("Subjects");
    for (const auto *Subject : Subjects) {
      if (!isSupportedPragmaClangAttributeSubject(*Subject))
        continue;
      auto It = SubjectsToRules.find(Subject);
      assert(It != SubjectsToRules.end() &&
             "This attribute is unsupported by #pragma clang attribute");
      for (const auto &Rule : It->getSecond().getAggregateRuleSet()) {
        // The rule might be language specific, so only subtract it from the given
        // rules if the specific language options are specified.
        std::vector<Record *> LangOpts = Rule.getLangOpts();
        OS << "  MatchRules.push_back(std::make_pair(" << Rule.getEnumValue()
           << ", /*IsSupported=*/" << GenerateTestExpression(LangOpts, true)
           << "));\n";
      }
    }
    OS << "}\n\n";
  }
  
  void PragmaClangAttributeSupport::generateParsingHelpers(raw_ostream &OS) {
    // Generate routines that check the names of sub-rules.
    OS << "Optional<attr::SubjectMatchRule> "
          "defaultIsAttributeSubjectMatchSubRuleFor(StringRef, bool) {\n";
    OS << "  return None;\n";
    OS << "}\n\n";
  
    std::map<const Record *, std::vector<AttributeSubjectMatchRule>>
        SubMatchRules;
    for (const auto &Rule : Rules) {
      if (!Rule.isSubRule())
        continue;
      SubMatchRules[Rule.MetaSubject].push_back(Rule);
    }
  
    for (const auto &SubMatchRule : SubMatchRules) {
      OS << "Optional<attr::SubjectMatchRule> isAttributeSubjectMatchSubRuleFor_"
         << SubMatchRule.first->getValueAsString("Name")
         << "(StringRef Name, bool IsUnless) {\n";
      OS << "  if (IsUnless)\n";
      OS << "    return "
            "llvm::StringSwitch<Optional<attr::SubjectMatchRule>>(Name).\n";
      for (const auto &Rule : SubMatchRule.second) {
        if (Rule.isNegatedSubRule())
          OS << "    Case(\"" << Rule.getName() << "\", " << Rule.getEnumValue()
             << ").\n";
      }
      OS << "    Default(None);\n";
      OS << "  return "
            "llvm::StringSwitch<Optional<attr::SubjectMatchRule>>(Name).\n";
      for (const auto &Rule : SubMatchRule.second) {
        if (!Rule.isNegatedSubRule())
          OS << "  Case(\"" << Rule.getName() << "\", " << Rule.getEnumValue()
             << ").\n";
      }
      OS << "  Default(None);\n";
      OS << "}\n\n";
    }
  
    // Generate the function that checks for the top-level rules.
    OS << "std::pair<Optional<attr::SubjectMatchRule>, "
          "Optional<attr::SubjectMatchRule> (*)(StringRef, "
          "bool)> isAttributeSubjectMatchRule(StringRef Name) {\n";
    OS << "  return "
          "llvm::StringSwitch<std::pair<Optional<attr::SubjectMatchRule>, "
          "Optional<attr::SubjectMatchRule> (*) (StringRef, "
          "bool)>>(Name).\n";
    for (const auto &Rule : Rules) {
      if (Rule.isSubRule())
        continue;
      std::string SubRuleFunction;
      if (SubMatchRules.count(Rule.MetaSubject))
        SubRuleFunction =
            ("isAttributeSubjectMatchSubRuleFor_" + Rule.getName()).str();
      else
        SubRuleFunction = "defaultIsAttributeSubjectMatchSubRuleFor";
      OS << "  Case(\"" << Rule.getName() << "\", std::make_pair("
         << Rule.getEnumValue() << ", " << SubRuleFunction << ")).\n";
    }
    OS << "  Default(std::make_pair(None, "
          "defaultIsAttributeSubjectMatchSubRuleFor));\n";
    OS << "}\n\n";
  
    // Generate the function that checks for the submatch rules.
    OS << "const char *validAttributeSubjectMatchSubRules("
       << AttributeSubjectMatchRule::EnumName << " Rule) {\n";
    OS << "  switch (Rule) {\n";
    for (const auto &SubMatchRule : SubMatchRules) {
      OS << "  case "
         << AttributeSubjectMatchRule(SubMatchRule.first, nullptr).getEnumValue()
         << ":\n";
      OS << "  return \"'";
      bool IsFirst = true;
      for (const auto &Rule : SubMatchRule.second) {
        if (!IsFirst)
          OS << ", '";
        IsFirst = false;
        if (Rule.isNegatedSubRule())
          OS << "unless(";
        OS << Rule.getName();
        if (Rule.isNegatedSubRule())
          OS << ')';
        OS << "'";
      }
      OS << "\";\n";
    }
    OS << "  default: return nullptr;\n";
    OS << "  }\n";
    OS << "}\n\n";
  }
  
  template <typename Fn>
  static void forEachUniqueSpelling(const Record &Attr, Fn &&F) {
    std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(Attr);
    SmallDenseSet<StringRef, 8> Seen;
    for (const FlattenedSpelling &S : Spellings) {
      if (Seen.insert(S.name()).second)
        F(S);
    }
  }
  
  /// Emits the first-argument-is-type property for attributes.
  static void emitClangAttrTypeArgList(RecordKeeper &Records, raw_ostream &OS) {
    OS << "#if defined(CLANG_ATTR_TYPE_ARG_LIST)\n";
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
  
    for (const auto *Attr : Attrs) {
      // Determine whether the first argument is a type.
      std::vector<Record *> Args = Attr->getValueAsListOfDefs("Args");
      if (Args.empty())
        continue;
  
      if (Args[0]->getSuperClasses().back().first->getName() != "TypeArgument")
        continue;
  
      // All these spellings take a single type argument.
      forEachUniqueSpelling(*Attr, [&](const FlattenedSpelling &S) {
        OS << ".Case(\"" << S.name() << "\", " << "true" << ")\n";
      });
    }
    OS << "#endif // CLANG_ATTR_TYPE_ARG_LIST\n\n";
  }
  
  /// Emits the parse-arguments-in-unevaluated-context property for
  /// attributes.
  static void emitClangAttrArgContextList(RecordKeeper &Records, raw_ostream &OS) {
    OS << "#if defined(CLANG_ATTR_ARG_CONTEXT_LIST)\n";
    ParsedAttrMap Attrs = getParsedAttrList(Records);
    for (const auto &I : Attrs) {
      const Record &Attr = *I.second;
  
      if (!Attr.getValueAsBit("ParseArgumentsAsUnevaluated"))
        continue;
  
      // All these spellings take are parsed unevaluated.
      forEachUniqueSpelling(Attr, [&](const FlattenedSpelling &S) {
        OS << ".Case(\"" << S.name() << "\", " << "true" << ")\n";
      });
    }
    OS << "#endif // CLANG_ATTR_ARG_CONTEXT_LIST\n\n";
  }
  
  static bool isIdentifierArgument(Record *Arg) {
    return !Arg->getSuperClasses().empty() &&
      llvm::StringSwitch<bool>(Arg->getSuperClasses().back().first->getName())
      .Case("IdentifierArgument", true)
      .Case("EnumArgument", true)
      .Case("VariadicEnumArgument", true)
      .Default(false);
  }
  
  static bool isVariadicIdentifierArgument(Record *Arg) {
    return !Arg->getSuperClasses().empty() &&
           llvm::StringSwitch<bool>(
               Arg->getSuperClasses().back().first->getName())
               .Case("VariadicIdentifierArgument", true)
               .Case("VariadicParamOrParamIdxArgument", true)
               .Default(false);
  }
  
  static void emitClangAttrVariadicIdentifierArgList(RecordKeeper &Records,
                                                     raw_ostream &OS) {
    OS << "#if defined(CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST)\n";
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    for (const auto *A : Attrs) {
      // Determine whether the first argument is a variadic identifier.
      std::vector<Record *> Args = A->getValueAsListOfDefs("Args");
      if (Args.empty() || !isVariadicIdentifierArgument(Args[0]))
        continue;
  
      // All these spellings take an identifier argument.
      forEachUniqueSpelling(*A, [&](const FlattenedSpelling &S) {
        OS << ".Case(\"" << S.name() << "\", "
           << "true"
           << ")\n";
      });
    }
    OS << "#endif // CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST\n\n";
  }
  
  // Emits the first-argument-is-identifier property for attributes.
  static void emitClangAttrIdentifierArgList(RecordKeeper &Records, raw_ostream &OS) {
    OS << "#if defined(CLANG_ATTR_IDENTIFIER_ARG_LIST)\n";
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr");
  
    for (const auto *Attr : Attrs) {
      // Determine whether the first argument is an identifier.
      std::vector<Record *> Args = Attr->getValueAsListOfDefs("Args");
      if (Args.empty() || !isIdentifierArgument(Args[0]))
        continue;
  
      // All these spellings take an identifier argument.
      forEachUniqueSpelling(*Attr, [&](const FlattenedSpelling &S) {
        OS << ".Case(\"" << S.name() << "\", " << "true" << ")\n";
      });
    }
    OS << "#endif // CLANG_ATTR_IDENTIFIER_ARG_LIST\n\n";
  }
  
  static bool keywordThisIsaIdentifierInArgument(const Record *Arg) {
    return !Arg->getSuperClasses().empty() &&
           llvm::StringSwitch<bool>(
               Arg->getSuperClasses().back().first->getName())
               .Case("VariadicParamOrParamIdxArgument", true)
               .Default(false);
  }
  
  static void emitClangAttrThisIsaIdentifierArgList(RecordKeeper &Records,
                                                    raw_ostream &OS) {
    OS << "#if defined(CLANG_ATTR_THIS_ISA_IDENTIFIER_ARG_LIST)\n";
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    for (const auto *A : Attrs) {
      // Determine whether the first argument is a variadic identifier.
      std::vector<Record *> Args = A->getValueAsListOfDefs("Args");
      if (Args.empty() || !keywordThisIsaIdentifierInArgument(Args[0]))
        continue;
  
      // All these spellings take an identifier argument.
      forEachUniqueSpelling(*A, [&](const FlattenedSpelling &S) {
        OS << ".Case(\"" << S.name() << "\", "
           << "true"
           << ")\n";
      });
    }
    OS << "#endif // CLANG_ATTR_THIS_ISA_IDENTIFIER_ARG_LIST\n\n";
  }
  
  static void emitAttributes(RecordKeeper &Records, raw_ostream &OS,
                             bool Header) {
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr");
    ParsedAttrMap AttrMap = getParsedAttrList(Records);
  
    // Helper to print the starting character of an attribute argument. If there
    // hasn't been an argument yet, it prints an opening parenthese; otherwise it
    // prints a comma.
    OS << "static inline void DelimitAttributeArgument("
       << "raw_ostream& OS, bool& IsFirst) {\n"
       << "  if (IsFirst) {\n"
       << "    IsFirst = false;\n"
       << "    OS << \"(\";\n"
       << "  } else\n"
       << "    OS << \", \";\n"
       << "}\n";
  
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
  
      // FIXME: Currently, documentation is generated as-needed due to the fact
      // that there is no way to allow a generated project "reach into" the docs
      // directory (for instance, it may be an out-of-tree build). However, we want
      // to ensure that every attribute has a Documentation field, and produce an
      // error if it has been neglected. Otherwise, the on-demand generation which
      // happens server-side will fail. This code is ensuring that functionality,
      // even though this Emitter doesn't technically need the documentation.
      // When attribute documentation can be generated as part of the build
      // itself, this code can be removed.
      (void)R.getValueAsListOfDefs("Documentation");
  
      if (!R.getValueAsBit("ASTNode"))
        continue;
  
      ArrayRef<std::pair<Record *, SMRange>> Supers = R.getSuperClasses();
      assert(!Supers.empty() && "Forgot to specify a superclass for the attr");
      std::string SuperName;
      bool Inheritable = false;
      for (const auto &Super : llvm::reverse(Supers)) {
        const Record *R = Super.first;
        if (R->getName() != "TargetSpecificAttr" &&
            R->getName() != "DeclOrTypeAttr" && SuperName.empty())
          SuperName = std::string(R->getName());
        if (R->getName() == "InheritableAttr")
          Inheritable = true;
      }
  
      if (Header)
        OS << "class " << R.getName() << "Attr : public " << SuperName << " {\n";
      else
        OS << "\n// " << R.getName() << "Attr implementation\n\n";
  
      std::vector<Record*> ArgRecords = R.getValueAsListOfDefs("Args");
      std::vector<std::unique_ptr<Argument>> Args;
      Args.reserve(ArgRecords.size());
  
      bool HasOptArg = false;
      bool HasFakeArg = false;
      for (const auto *ArgRecord : ArgRecords) {
        Args.emplace_back(createArgument(*ArgRecord, R.getName()));
        if (Header) {
          Args.back()->writeDeclarations(OS);
          OS << "\n\n";
        }
  
        // For these purposes, fake takes priority over optional.
        if (Args.back()->isFake()) {
          HasFakeArg = true;
        } else if (Args.back()->isOptional()) {
          HasOptArg = true;
        }
      }
  
      if (Header)
        OS << "public:\n";
  
      std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(R);
  
      // If there are zero or one spellings, all spelling-related functionality
      // can be elided. If all of the spellings share the same name, the spelling
      // functionality can also be elided.
      bool ElideSpelling = (Spellings.size() <= 1) ||
                           SpellingNamesAreCommon(Spellings);
  
      // This maps spelling index values to semantic Spelling enumerants.
      SemanticSpellingMap SemanticToSyntacticMap;
  
      std::string SpellingEnum;
      if (Spellings.size() > 1)
        SpellingEnum = CreateSemanticSpellings(Spellings, SemanticToSyntacticMap);
      if (Header)
        OS << SpellingEnum;
  
      const auto &ParsedAttrSpellingItr = llvm::find_if(
          AttrMap, [R](const std::pair<std::string, const Record *> &P) {
            return &R == P.second;
          });
  
      // Emit CreateImplicit factory methods.
      auto emitCreate = [&](bool Implicit, bool emitFake) {
        if (Header)
          OS << "  static ";
        OS << R.getName() << "Attr *";
        if (!Header)
          OS << R.getName() << "Attr::";
        OS << "Create";
        if (Implicit)
          OS << "Implicit";
        OS << "(";
        OS << "ASTContext &Ctx";
        for (auto const &ai : Args) {
          if (ai->isFake() && !emitFake) continue;
          OS << ", ";
          ai->writeCtorParameters(OS);
        }
        OS << ", const AttributeCommonInfo &CommonInfo";
        if (Header && Implicit)
          OS << " = {SourceRange{}}";
        OS << ")";
        if (Header) {
          OS << ";\n";
          return;
        }
  
        OS << " {\n";
        OS << "  auto *A = new (Ctx) " << R.getName();
        OS << "Attr(Ctx, CommonInfo";
        for (auto const &ai : Args) {
          if (ai->isFake() && !emitFake) continue;
          OS << ", ";
          ai->writeImplicitCtorArgs(OS);
        }
        OS << ");\n";
        if (Implicit) {
          OS << "  A->setImplicit(true);\n";
        }
        if (Implicit || ElideSpelling) {
          OS << "  if (!A->isAttributeSpellingListCalculated() && "
                "!A->getAttrName())\n";
          OS << "    A->setAttributeSpellingListIndex(0);\n";
        }
        OS << "  return A;\n}\n\n";
      };
  
      auto emitCreateNoCI = [&](bool Implicit, bool emitFake) {
        if (Header)
          OS << "  static ";
        OS << R.getName() << "Attr *";
        if (!Header)
          OS << R.getName() << "Attr::";
        OS << "Create";
        if (Implicit)
          OS << "Implicit";
        OS << "(";
        OS << "ASTContext &Ctx";
        for (auto const &ai : Args) {
          if (ai->isFake() && !emitFake) continue;
          OS << ", ";
          ai->writeCtorParameters(OS);
        }
        OS << ", SourceRange Range, AttributeCommonInfo::Syntax Syntax";
        if (!ElideSpelling) {
          OS << ", " << R.getName() << "Attr::Spelling S";
          if (Header)
            OS << " = static_cast<Spelling>(SpellingNotCalculated)";
        }
        OS << ")";
        if (Header) {
          OS << ";\n";
          return;
        }
  
        OS << " {\n";
        OS << "  AttributeCommonInfo I(Range, ";
  
        if (ParsedAttrSpellingItr != std::end(AttrMap))
          OS << "AT_" << ParsedAttrSpellingItr->first;
        else
          OS << "NoSemaHandlerAttribute";
  
        OS << ", Syntax";
        if (!ElideSpelling)
          OS << ", S";
        OS << ");\n";
        OS << "  return Create";
        if (Implicit)
          OS << "Implicit";
        OS << "(Ctx";
        for (auto const &ai : Args) {
          if (ai->isFake() && !emitFake) continue;
          OS << ", ";
          ai->writeImplicitCtorArgs(OS);
        }
        OS << ", I);\n";
        OS << "}\n\n";
      };
  
      auto emitCreates = [&](bool emitFake) {
        emitCreate(true, emitFake);
        emitCreate(false, emitFake);
        emitCreateNoCI(true, emitFake);
        emitCreateNoCI(false, emitFake);
      };
  
      if (Header)
        OS << "  // Factory methods\n";
  
      // Emit a CreateImplicit that takes all the arguments.
      emitCreates(true);
  
      // Emit a CreateImplicit that takes all the non-fake arguments.
      if (HasFakeArg)
        emitCreates(false);
  
      // Emit constructors.
      auto emitCtor = [&](bool emitOpt, bool emitFake) {
        auto shouldEmitArg = [=](const std::unique_ptr<Argument> &arg) {
          if (arg->isFake()) return emitFake;
          if (arg->isOptional()) return emitOpt;
          return true;
        };
        if (Header)
          OS << "  ";
        else
          OS << R.getName() << "Attr::";
        OS << R.getName()
           << "Attr(ASTContext &Ctx, const AttributeCommonInfo &CommonInfo";
        OS << '\n';
        for (auto const &ai : Args) {
          if (!shouldEmitArg(ai)) continue;
          OS << "              , ";
          ai->writeCtorParameters(OS);
          OS << "\n";
        }
  
        OS << "             )";
        if (Header) {
          OS << ";\n";
          return;
        }
        OS << "\n  : " << SuperName << "(Ctx, CommonInfo, ";
        OS << "attr::" << R.getName() << ", "
           << (R.getValueAsBit("LateParsed") ? "true" : "false");
        if (Inheritable) {
          OS << ", "
             << (R.getValueAsBit("InheritEvenIfAlreadyPresent") ? "true"
                                                                : "false");
        }
        OS << ")\n";
  
        for (auto const &ai : Args) {
          OS << "              , ";
          if (!shouldEmitArg(ai)) {
            ai->writeCtorDefaultInitializers(OS);
          } else {
            ai->writeCtorInitializers(OS);
          }
          OS << "\n";
        }
  
        OS << "  {\n";
  
        for (auto const &ai : Args) {
          if (!shouldEmitArg(ai)) continue;
          ai->writeCtorBody(OS);
        }
        OS << "}\n\n";
      };
  
      if (Header)
        OS << "\n  // Constructors\n";
  
      // Emit a constructor that includes all the arguments.
      // This is necessary for cloning.
      emitCtor(true, true);
  
      // Emit a constructor that takes all the non-fake arguments.
      if (HasFakeArg)
        emitCtor(true, false);
  
      // Emit a constructor that takes all the non-fake, non-optional arguments.
      if (HasOptArg)
        emitCtor(false, false);
  
      if (Header) {
        OS << '\n';
        OS << "  " << R.getName() << "Attr *clone(ASTContext &C) const;\n";
        OS << "  void printPretty(raw_ostream &OS,\n"
           << "                   const PrintingPolicy &Policy) const;\n";
        OS << "  const char *getSpelling() const;\n";
      }
  
      if (!ElideSpelling) {
        assert(!SemanticToSyntacticMap.empty() && "Empty semantic mapping list");
        if (Header)
          OS << "  Spelling getSemanticSpelling() const;\n";
        else {
          OS << R.getName() << "Attr::Spelling " << R.getName()
             << "Attr::getSemanticSpelling() const {\n";
          WriteSemanticSpellingSwitch("getAttributeSpellingListIndex()",
                                      SemanticToSyntacticMap, OS);
          OS << "}\n";
        }
      }
  
      if (Header)
        writeAttrAccessorDefinition(R, OS);
  
      for (auto const &ai : Args) {
        if (Header) {
          ai->writeAccessors(OS);
        } else {
          ai->writeAccessorDefinitions(OS);
        }
        OS << "\n\n";
  
        // Don't write conversion routines for fake arguments.
        if (ai->isFake()) continue;
  
        if (ai->isEnumArg())
          static_cast<const EnumArgument *>(ai.get())->writeConversion(OS,
                                                                       Header);
        else if (ai->isVariadicEnumArg())
          static_cast<const VariadicEnumArgument *>(ai.get())->writeConversion(
              OS, Header);
      }
  
      if (Header) {
        OS << R.getValueAsString("AdditionalMembers");
        OS << "\n\n";
  
        OS << "  static bool classof(const Attr *A) { return A->getKind() == "
           << "attr::" << R.getName() << "; }\n";
  
        OS << "};\n\n";
      } else {
        OS << R.getName() << "Attr *" << R.getName()
           << "Attr::clone(ASTContext &C) const {\n";
        OS << "  auto *A = new (C) " << R.getName() << "Attr(C, *this";
        for (auto const &ai : Args) {
          OS << ", ";
          ai->writeCloneArgs(OS);
        }
        OS << ");\n";
        OS << "  A->Inherited = Inherited;\n";
        OS << "  A->IsPackExpansion = IsPackExpansion;\n";
        OS << "  A->setImplicit(Implicit);\n";
        OS << "  return A;\n}\n\n";
  
        writePrettyPrintFunction(R, Args, OS);
        writeGetSpellingFunction(R, OS);
      }
    }
  }
  // Emits the class definitions for attributes.
  void clang::EmitClangAttrClass(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Attribute classes' definitions", OS);
  
    OS << "#ifndef LLVM_CLANG_ATTR_CLASSES_INC\n";
    OS << "#define LLVM_CLANG_ATTR_CLASSES_INC\n\n";
  
    emitAttributes(Records, OS, true);
  
    OS << "#endif // LLVM_CLANG_ATTR_CLASSES_INC\n";
  }
  
  // Emits the class method definitions for attributes.
  void clang::EmitClangAttrImpl(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Attribute classes' member function definitions", OS);
  
    emitAttributes(Records, OS, false);
  
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
  
    // Instead of relying on virtual dispatch we just create a huge dispatch
    // switch. This is both smaller and faster than virtual functions.
    auto EmitFunc = [&](const char *Method) {
      OS << "  switch (getKind()) {\n";
      for (const auto *Attr : Attrs) {
        const Record &R = *Attr;
        if (!R.getValueAsBit("ASTNode"))
          continue;
  
        OS << "  case attr::" << R.getName() << ":\n";
        OS << "    return cast<" << R.getName() << "Attr>(this)->" << Method
           << ";\n";
      }
      OS << "  }\n";
      OS << "  llvm_unreachable(\"Unexpected attribute kind!\");\n";
      OS << "}\n\n";
    };
  
    OS << "const char *Attr::getSpelling() const {\n";
    EmitFunc("getSpelling()");
  
    OS << "Attr *Attr::clone(ASTContext &C) const {\n";
    EmitFunc("clone(C)");
  
    OS << "void Attr::printPretty(raw_ostream &OS, "
          "const PrintingPolicy &Policy) const {\n";
    EmitFunc("printPretty(OS, Policy)");
  }
  
  static void emitAttrList(raw_ostream &OS, StringRef Class,
                           const std::vector<Record*> &AttrList) {
    for (auto Cur : AttrList) {
      OS << Class << "(" << Cur->getName() << ")\n";
    }
  }
  
  // Determines if an attribute has a Pragma spelling.
  static bool AttrHasPragmaSpelling(const Record *R) {
    std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(*R);
    return llvm::find_if(Spellings, [](const FlattenedSpelling &S) {
             return S.variety() == "Pragma";
           }) != Spellings.end();
  }
  
  namespace {
  
    struct AttrClassDescriptor {
      const char * const MacroName;
      const char * const TableGenName;
    };
  
  } // end anonymous namespace
  
  static const AttrClassDescriptor AttrClassDescriptors[] = {
    { "ATTR", "Attr" },
    { "TYPE_ATTR", "TypeAttr" },
    { "STMT_ATTR", "StmtAttr" },
    { "DECL_OR_STMT_ATTR", "DeclOrStmtAttr" },
    { "INHERITABLE_ATTR", "InheritableAttr" },
    { "DECL_OR_TYPE_ATTR", "DeclOrTypeAttr" },
    { "INHERITABLE_PARAM_ATTR", "InheritableParamAttr" },
    { "PARAMETER_ABI_ATTR", "ParameterABIAttr" }
  };
  
  static void emitDefaultDefine(raw_ostream &OS, StringRef name,
                                const char *superName) {
    OS << "#ifndef " << name << "\n";
    OS << "#define " << name << "(NAME) ";
    if (superName) OS << superName << "(NAME)";
    OS << "\n#endif\n\n";
  }
  
  namespace {
  
    /// A class of attributes.
    struct AttrClass {
      const AttrClassDescriptor &Descriptor;
      Record *TheRecord;
      AttrClass *SuperClass = nullptr;
      std::vector<AttrClass*> SubClasses;
      std::vector<Record*> Attrs;
  
      AttrClass(const AttrClassDescriptor &Descriptor, Record *R)
        : Descriptor(Descriptor), TheRecord(R) {}
  
      void emitDefaultDefines(raw_ostream &OS) const {
        // Default the macro unless this is a root class (i.e. Attr).
        if (SuperClass) {
          emitDefaultDefine(OS, Descriptor.MacroName,
                            SuperClass->Descriptor.MacroName);
        }
      }
  
      void emitUndefs(raw_ostream &OS) const {
        OS << "#undef " << Descriptor.MacroName << "\n";
      }
  
      void emitAttrList(raw_ostream &OS) const {
        for (auto SubClass : SubClasses) {
          SubClass->emitAttrList(OS);
        }
  
        ::emitAttrList(OS, Descriptor.MacroName, Attrs);
      }
  
      void classifyAttrOnRoot(Record *Attr) {
        bool result = classifyAttr(Attr);
        assert(result && "failed to classify on root"); (void) result;
      }
  
      void emitAttrRange(raw_ostream &OS) const {
        OS << "ATTR_RANGE(" << Descriptor.TableGenName
           << ", " << getFirstAttr()->getName()
           << ", " << getLastAttr()->getName() << ")\n";
      }
  
    private:
      bool classifyAttr(Record *Attr) {
        // Check all the subclasses.
        for (auto SubClass : SubClasses) {
          if (SubClass->classifyAttr(Attr))
            return true;
        }
  
        // It's not more specific than this class, but it might still belong here.
        if (Attr->isSubClassOf(TheRecord)) {
          Attrs.push_back(Attr);
          return true;
        }
  
        return false;
      }
  
      Record *getFirstAttr() const {
        if (!SubClasses.empty())
          return SubClasses.front()->getFirstAttr();
        return Attrs.front();
      }
  
      Record *getLastAttr() const {
        if (!Attrs.empty())
          return Attrs.back();
        return SubClasses.back()->getLastAttr();
      }
    };
  
    /// The entire hierarchy of attribute classes.
    class AttrClassHierarchy {
      std::vector<std::unique_ptr<AttrClass>> Classes;
  
    public:
      AttrClassHierarchy(RecordKeeper &Records) {
        // Find records for all the classes.
        for (auto &Descriptor : AttrClassDescriptors) {
          Record *ClassRecord = Records.getClass(Descriptor.TableGenName);
          AttrClass *Class = new AttrClass(Descriptor, ClassRecord);
          Classes.emplace_back(Class);
        }
  
        // Link up the hierarchy.
        for (auto &Class : Classes) {
          if (AttrClass *SuperClass = findSuperClass(Class->TheRecord)) {
            Class->SuperClass = SuperClass;
            SuperClass->SubClasses.push_back(Class.get());
          }
        }
  
  #ifndef NDEBUG
        for (auto i = Classes.begin(), e = Classes.end(); i != e; ++i) {
          assert((i == Classes.begin()) == ((*i)->SuperClass == nullptr) &&
                 "only the first class should be a root class!");
        }
  #endif
      }
  
      void emitDefaultDefines(raw_ostream &OS) const {
        for (auto &Class : Classes) {
          Class->emitDefaultDefines(OS);
        }
      }
  
      void emitUndefs(raw_ostream &OS) const {
        for (auto &Class : Classes) {
          Class->emitUndefs(OS);
        }
      }
  
      void emitAttrLists(raw_ostream &OS) const {
        // Just start from the root class.
        Classes[0]->emitAttrList(OS);
      }
  
      void emitAttrRanges(raw_ostream &OS) const {
        for (auto &Class : Classes)
          Class->emitAttrRange(OS);
      }
  
      void classifyAttr(Record *Attr) {
        // Add the attribute to the root class.
        Classes[0]->classifyAttrOnRoot(Attr);
      }
  
    private:
      AttrClass *findClassByRecord(Record *R) const {
        for (auto &Class : Classes) {
          if (Class->TheRecord == R)
            return Class.get();
        }
        return nullptr;
      }
  
      AttrClass *findSuperClass(Record *R) const {
        // TableGen flattens the superclass list, so we just need to walk it
        // in reverse.
        auto SuperClasses = R->getSuperClasses();
        for (signed i = 0, e = SuperClasses.size(); i != e; ++i) {
          auto SuperClass = findClassByRecord(SuperClasses[e - i - 1].first);
          if (SuperClass) return SuperClass;
        }
        return nullptr;
      }
    };
  
  } // end anonymous namespace
  
  namespace clang {
  
  // Emits the enumeration list for attributes.
  void EmitClangAttrList(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("List of all attributes that Clang recognizes", OS);
  
    AttrClassHierarchy Hierarchy(Records);
  
    // Add defaulting macro definitions.
    Hierarchy.emitDefaultDefines(OS);
    emitDefaultDefine(OS, "PRAGMA_SPELLING_ATTR", nullptr);
    emitDefaultDefine(OS, "DEPENDENT_STMT_ATTR", nullptr);
  
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    std::vector<Record *> PragmaAttrs;
    std::vector<Record *> DependentStmtAttrs;
    for (auto *Attr : Attrs) {
      if (!Attr->getValueAsBit("ASTNode"))
        continue;
  
      // Add the attribute to the ad-hoc groups.
      if (AttrHasPragmaSpelling(Attr))
        PragmaAttrs.push_back(Attr);
  
      if (Attr->getValueAsBit("IsStmtDependent"))
        DependentStmtAttrs.push_back(Attr);
  
      // Place it in the hierarchy.
      Hierarchy.classifyAttr(Attr);
    }
  
    // Emit the main attribute list.
    Hierarchy.emitAttrLists(OS);
  
    // Emit the ad hoc groups.
    emitAttrList(OS, "PRAGMA_SPELLING_ATTR", PragmaAttrs);
    emitAttrList(OS, "DEPENDENT_STMT_ATTR", DependentStmtAttrs);
  
    // Emit the attribute ranges.
    OS << "#ifdef ATTR_RANGE\n";
    Hierarchy.emitAttrRanges(OS);
    OS << "#undef ATTR_RANGE\n";
    OS << "#endif\n";
  
    Hierarchy.emitUndefs(OS);
    OS << "#undef DEPENDENT_STMT_ATTR\n";
    OS << "#undef PRAGMA_SPELLING_ATTR\n";
  }
  
  // Emits the enumeration list for attributes.
  void EmitClangAttrSubjectMatchRuleList(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader(
        "List of all attribute subject matching rules that Clang recognizes", OS);
    PragmaClangAttributeSupport &PragmaAttributeSupport =
        getPragmaAttributeSupport(Records);
    emitDefaultDefine(OS, "ATTR_MATCH_RULE", nullptr);
    PragmaAttributeSupport.emitMatchRuleList(OS);
    OS << "#undef ATTR_MATCH_RULE\n";
  }
  
  // Emits the code to read an attribute from a precompiled header.
  void EmitClangAttrPCHRead(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Attribute deserialization code", OS);
  
    Record *InhClass = Records.getClass("InheritableAttr");
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr"),
                         ArgRecords;
    std::vector<std::unique_ptr<Argument>> Args;
  
    OS << "  switch (Kind) {\n";
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
  
      OS << "  case attr::" << R.getName() << ": {\n";
      if (R.isSubClassOf(InhClass))
        OS << "    bool isInherited = Record.readInt();\n";
      OS << "    bool isImplicit = Record.readInt();\n";
      OS << "    bool isPackExpansion = Record.readInt();\n";
      ArgRecords = R.getValueAsListOfDefs("Args");
      Args.clear();
      for (const auto *Arg : ArgRecords) {
        Args.emplace_back(createArgument(*Arg, R.getName()));
        Args.back()->writePCHReadDecls(OS);
      }
      OS << "    New = new (Context) " << R.getName() << "Attr(Context, Info";
      for (auto const &ri : Args) {
        OS << ", ";
        ri->writePCHReadArgs(OS);
      }
      OS << ");\n";
      if (R.isSubClassOf(InhClass))
        OS << "    cast<InheritableAttr>(New)->setInherited(isInherited);\n";
      OS << "    New->setImplicit(isImplicit);\n";
      OS << "    New->setPackExpansion(isPackExpansion);\n";
      OS << "    break;\n";
      OS << "  }\n";
    }
    OS << "  }\n";
  }
  
  // Emits the code to write an attribute to a precompiled header.
  void EmitClangAttrPCHWrite(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Attribute serialization code", OS);
  
    Record *InhClass = Records.getClass("InheritableAttr");
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr"), Args;
  
    OS << "  switch (A->getKind()) {\n";
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
      OS << "  case attr::" << R.getName() << ": {\n";
      Args = R.getValueAsListOfDefs("Args");
      if (R.isSubClassOf(InhClass) || !Args.empty())
        OS << "    const auto *SA = cast<" << R.getName()
           << "Attr>(A);\n";
      if (R.isSubClassOf(InhClass))
        OS << "    Record.push_back(SA->isInherited());\n";
      OS << "    Record.push_back(A->isImplicit());\n";
      OS << "    Record.push_back(A->isPackExpansion());\n";
  
      for (const auto *Arg : Args)
        createArgument(*Arg, R.getName())->writePCHWrite(OS);
      OS << "    break;\n";
      OS << "  }\n";
    }
    OS << "  }\n";
  }
  
  // Helper function for GenerateTargetSpecificAttrChecks that alters the 'Test'
  // parameter with only a single check type, if applicable.
  static bool GenerateTargetSpecificAttrCheck(const Record *R, std::string &Test,
                                              std::string *FnName,
                                              StringRef ListName,
                                              StringRef CheckAgainst,
                                              StringRef Scope) {
    if (!R->isValueUnset(ListName)) {
      Test += " && (";
      std::vector<StringRef> Items = R->getValueAsListOfStrings(ListName);
      for (auto I = Items.begin(), E = Items.end(); I != E; ++I) {
        StringRef Part = *I;
        Test += CheckAgainst;
        Test += " == ";
        Test += Scope;
        Test += Part;
        if (I + 1 != E)
          Test += " || ";
        if (FnName)
          *FnName += Part;
      }
      Test += ")";
      return true;
    }
    return false;
  }
  
  // Generate a conditional expression to check if the current target satisfies
  // the conditions for a TargetSpecificAttr record, and append the code for
  // those checks to the Test string. If the FnName string pointer is non-null,
  // append a unique suffix to distinguish this set of target checks from other
  // TargetSpecificAttr records.
  static bool GenerateTargetSpecificAttrChecks(const Record *R,
                                               std::vector<StringRef> &Arches,
                                               std::string &Test,
                                               std::string *FnName) {
    bool AnyTargetChecks = false;
  
    // It is assumed that there will be an llvm::Triple object
    // named "T" and a TargetInfo object named "Target" within
    // scope that can be used to determine whether the attribute exists in
    // a given target.
    Test += "true";
    // If one or more architectures is specified, check those.  Arches are handled
    // differently because GenerateTargetRequirements needs to combine the list
    // with ParseKind.
    if (!Arches.empty()) {
      AnyTargetChecks = true;
      Test += " && (";
      for (auto I = Arches.begin(), E = Arches.end(); I != E; ++I) {
        StringRef Part = *I;
        Test += "T.getArch() == llvm::Triple::";
        Test += Part;
        if (I + 1 != E)
          Test += " || ";
        if (FnName)
          *FnName += Part;
      }
      Test += ")";
    }
  
    // If the attribute is specific to particular OSes, check those.
    AnyTargetChecks |= GenerateTargetSpecificAttrCheck(
        R, Test, FnName, "OSes", "T.getOS()", "llvm::Triple::");
  
    // If one or more object formats is specified, check those.
    AnyTargetChecks |=
        GenerateTargetSpecificAttrCheck(R, Test, FnName, "ObjectFormats",
                                        "T.getObjectFormat()", "llvm::Triple::");
  
    // If custom code is specified, emit it.
    StringRef Code = R->getValueAsString("CustomCode");
    if (!Code.empty()) {
      AnyTargetChecks = true;
      Test += " && (";
      Test += Code;
      Test += ")";
    }
  
    return AnyTargetChecks;
  }
  
  static void GenerateHasAttrSpellingStringSwitch(
      const std::vector<Record *> &Attrs, raw_ostream &OS,
      const std::string &Variety = "", const std::string &Scope = "") {
    for (const auto *Attr : Attrs) {
      // C++11-style attributes have specific version information associated with
      // them. If the attribute has no scope, the version information must not
      // have the default value (1), as that's incorrect. Instead, the unscoped
      // attribute version information should be taken from the SD-6 standing
      // document, which can be found at:
      // https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
      //
      // C2x-style attributes have the same kind of version information
      // associated with them. The unscoped attribute version information should
      // be taken from the specification of the attribute in the C Standard.
      int Version = 1;
  
      if (Variety == "CXX11" || Variety == "C2x") {
        std::vector<Record *> Spellings = Attr->getValueAsListOfDefs("Spellings");
        for (const auto &Spelling : Spellings) {
          if (Spelling->getValueAsString("Variety") == Variety) {
            Version = static_cast<int>(Spelling->getValueAsInt("Version"));
            if (Scope.empty() && Version == 1)
              PrintError(Spelling->getLoc(), "Standard attributes must have "
                                             "valid version information.");
            break;
          }
        }
      }
  
      std::string Test;
      if (Attr->isSubClassOf("TargetSpecificAttr")) {
        const Record *R = Attr->getValueAsDef("Target");
        std::vector<StringRef> Arches = R->getValueAsListOfStrings("Arches");
        GenerateTargetSpecificAttrChecks(R, Arches, Test, nullptr);
  
        // If this is the C++11 variety, also add in the LangOpts test.
        if (Variety == "CXX11")
          Test += " && LangOpts.CPlusPlus11";
        else if (Variety == "C2x")
          Test += " && LangOpts.DoubleSquareBracketAttributes";
      } else if (Variety == "CXX11")
        // C++11 mode should be checked against LangOpts, which is presumed to be
        // present in the caller.
        Test = "LangOpts.CPlusPlus11";
      else if (Variety == "C2x")
        Test = "LangOpts.DoubleSquareBracketAttributes";
  
      std::string TestStr =
          !Test.empty() ? Test + " ? " + llvm::itostr(Version) + " : 0" : "1";
      std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(*Attr);
      for (const auto &S : Spellings)
        if (Variety.empty() || (Variety == S.variety() &&
                                (Scope.empty() || Scope == S.nameSpace())))
          OS << "    .Case(\"" << S.name() << "\", " << TestStr << ")\n";
    }
    OS << "    .Default(0);\n";
  }
  
  // Emits the list of spellings for attributes.
  void EmitClangAttrHasAttrImpl(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Code to implement the __has_attribute logic", OS);
  
    // Separate all of the attributes out into four group: generic, C++11, GNU,
    // and declspecs. Then generate a big switch statement for each of them.
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    std::vector<Record *> Declspec, Microsoft, GNU, Pragma;
    std::map<std::string, std::vector<Record *>> CXX, C2x;
  
    // Walk over the list of all attributes, and split them out based on the
    // spelling variety.
    for (auto *R : Attrs) {
      std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(*R);
      for (const auto &SI : Spellings) {
        const std::string &Variety = SI.variety();
        if (Variety == "GNU")
          GNU.push_back(R);
        else if (Variety == "Declspec")
          Declspec.push_back(R);
        else if (Variety == "Microsoft")
          Microsoft.push_back(R);
        else if (Variety == "CXX11")
          CXX[SI.nameSpace()].push_back(R);
        else if (Variety == "C2x")
          C2x[SI.nameSpace()].push_back(R);
        else if (Variety == "Pragma")
          Pragma.push_back(R);
      }
    }
  
    OS << "const llvm::Triple &T = Target.getTriple();\n";
    OS << "switch (Syntax) {\n";
    OS << "case AttrSyntax::GNU:\n";
    OS << "  return llvm::StringSwitch<int>(Name)\n";
    GenerateHasAttrSpellingStringSwitch(GNU, OS, "GNU");
    OS << "case AttrSyntax::Declspec:\n";
    OS << "  return llvm::StringSwitch<int>(Name)\n";
    GenerateHasAttrSpellingStringSwitch(Declspec, OS, "Declspec");
    OS << "case AttrSyntax::Microsoft:\n";
    OS << "  return llvm::StringSwitch<int>(Name)\n";
    GenerateHasAttrSpellingStringSwitch(Microsoft, OS, "Microsoft");
    OS << "case AttrSyntax::Pragma:\n";
    OS << "  return llvm::StringSwitch<int>(Name)\n";
    GenerateHasAttrSpellingStringSwitch(Pragma, OS, "Pragma");
    auto fn = [&OS](const char *Spelling, const char *Variety,
                    const std::map<std::string, std::vector<Record *>> &List) {
      OS << "case AttrSyntax::" << Variety << ": {\n";
      // C++11-style attributes are further split out based on the Scope.
      for (auto I = List.cbegin(), E = List.cend(); I != E; ++I) {
        if (I != List.cbegin())
          OS << " else ";
        if (I->first.empty())
          OS << "if (ScopeName == \"\") {\n";
        else
          OS << "if (ScopeName == \"" << I->first << "\") {\n";
        OS << "  return llvm::StringSwitch<int>(Name)\n";
        GenerateHasAttrSpellingStringSwitch(I->second, OS, Spelling, I->first);
        OS << "}";
      }
      OS << "\n} break;\n";
    };
    fn("CXX11", "CXX", CXX);
    fn("C2x", "C", C2x);
    OS << "}\n";
  }
  
  void EmitClangAttrSpellingListIndex(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Code to translate different attribute spellings "
                         "into internal identifiers", OS);
  
    OS << "  switch (getParsedKind()) {\n";
    OS << "    case IgnoredAttribute:\n";
    OS << "    case UnknownAttribute:\n";
    OS << "    case NoSemaHandlerAttribute:\n";
    OS << "      llvm_unreachable(\"Ignored/unknown shouldn't get here\");\n";
  
    ParsedAttrMap Attrs = getParsedAttrList(Records);
    for (const auto &I : Attrs) {
      const Record &R = *I.second;
      std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(R);
      OS << "  case AT_" << I.first << ": {\n";
      for (unsigned I = 0; I < Spellings.size(); ++ I) {
        OS << "    if (Name == \"" << Spellings[I].name() << "\" && "
           << "getSyntax() == AttributeCommonInfo::AS_" << Spellings[I].variety()
           << " && Scope == \"" << Spellings[I].nameSpace() << "\")\n"
           << "        return " << I << ";\n";
      }
  
      OS << "    break;\n";
      OS << "  }\n";
    }
  
    OS << "  }\n";
    OS << "  return 0;\n";
  }
  
  // Emits code used by RecursiveASTVisitor to visit attributes
  void EmitClangAttrASTVisitor(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Used by RecursiveASTVisitor to visit attributes.", OS);
  
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr");
  
    // Write method declarations for Traverse* methods.
    // We emit this here because we only generate methods for attributes that
    // are declared as ASTNodes.
    OS << "#ifdef ATTR_VISITOR_DECLS_ONLY\n\n";
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
      OS << "  bool Traverse"
         << R.getName() << "Attr(" << R.getName() << "Attr *A);\n";
      OS << "  bool Visit"
         << R.getName() << "Attr(" << R.getName() << "Attr *A) {\n"
         << "    return true; \n"
         << "  }\n";
    }
    OS << "\n#else // ATTR_VISITOR_DECLS_ONLY\n\n";
  
    // Write individual Traverse* methods for each attribute class.
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
  
      OS << "template <typename Derived>\n"
         << "bool VISITORCLASS<Derived>::Traverse"
         << R.getName() << "Attr(" << R.getName() << "Attr *A) {\n"
         << "  if (!getDerived().VisitAttr(A))\n"
         << "    return false;\n"
         << "  if (!getDerived().Visit" << R.getName() << "Attr(A))\n"
         << "    return false;\n";
  
      std::vector<Record*> ArgRecords = R.getValueAsListOfDefs("Args");
      for (const auto *Arg : ArgRecords)
        createArgument(*Arg, R.getName())->writeASTVisitorTraversal(OS);
  
      OS << "  return true;\n";
      OS << "}\n\n";
    }
  
    // Write generic Traverse routine
    OS << "template <typename Derived>\n"
       << "bool VISITORCLASS<Derived>::TraverseAttr(Attr *A) {\n"
       << "  if (!A)\n"
       << "    return true;\n"
       << "\n"
       << "  switch (A->getKind()) {\n";
  
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
  
      OS << "    case attr::" << R.getName() << ":\n"
         << "      return getDerived().Traverse" << R.getName() << "Attr("
         << "cast<" << R.getName() << "Attr>(A));\n";
    }
    OS << "  }\n";  // end switch
    OS << "  llvm_unreachable(\"bad attribute kind\");\n";
    OS << "}\n";  // end function
    OS << "#endif  // ATTR_VISITOR_DECLS_ONLY\n";
  }
  
  void EmitClangAttrTemplateInstantiateHelper(const std::vector<Record *> &Attrs,
                                              raw_ostream &OS,
                                              bool AppliesToDecl) {
  
    OS << "  switch (At->getKind()) {\n";
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
      OS << "    case attr::" << R.getName() << ": {\n";
      bool ShouldClone = R.getValueAsBit("Clone") &&
                         (!AppliesToDecl ||
                          R.getValueAsBit("MeaningfulToClassTemplateDefinition"));
  
      if (!ShouldClone) {
        OS << "      return nullptr;\n";
        OS << "    }\n";
        continue;
      }
  
      OS << "      const auto *A = cast<"
         << R.getName() << "Attr>(At);\n";
      bool TDependent = R.getValueAsBit("TemplateDependent");
  
      if (!TDependent) {
        OS << "      return A->clone(C);\n";
        OS << "    }\n";
        continue;
      }
  
      std::vector<Record*> ArgRecords = R.getValueAsListOfDefs("Args");
      std::vector<std::unique_ptr<Argument>> Args;
      Args.reserve(ArgRecords.size());
  
      for (const auto *ArgRecord : ArgRecords)
        Args.emplace_back(createArgument(*ArgRecord, R.getName()));
  
      for (auto const &ai : Args)
        ai->writeTemplateInstantiation(OS);
  
      OS << "      return new (C) " << R.getName() << "Attr(C, *A";
      for (auto const &ai : Args) {
        OS << ", ";
        ai->writeTemplateInstantiationArgs(OS);
      }
      OS << ");\n"
         << "    }\n";
    }
    OS << "  } // end switch\n"
       << "  llvm_unreachable(\"Unknown attribute!\");\n"
       << "  return nullptr;\n";
  }
  
  // Emits code to instantiate dependent attributes on templates.
  void EmitClangAttrTemplateInstantiate(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Template instantiation code for attributes", OS);
  
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr");
  
    OS << "namespace clang {\n"
       << "namespace sema {\n\n"
       << "Attr *instantiateTemplateAttribute(const Attr *At, ASTContext &C, "
       << "Sema &S,\n"
       << "        const MultiLevelTemplateArgumentList &TemplateArgs) {\n";
    EmitClangAttrTemplateInstantiateHelper(Attrs, OS, /*AppliesToDecl*/false);
    OS << "}\n\n"
       << "Attr *instantiateTemplateAttributeForDecl(const Attr *At,\n"
       << " ASTContext &C, Sema &S,\n"
       << "        const MultiLevelTemplateArgumentList &TemplateArgs) {\n";
    EmitClangAttrTemplateInstantiateHelper(Attrs, OS, /*AppliesToDecl*/true);
    OS << "}\n\n"
       << "} // end namespace sema\n"
       << "} // end namespace clang\n";
  }
  
  // Emits the list of parsed attributes.
  void EmitClangAttrParsedAttrList(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("List of all attributes that Clang recognizes", OS);
  
    OS << "#ifndef PARSED_ATTR\n";
    OS << "#define PARSED_ATTR(NAME) NAME\n";
    OS << "#endif\n\n";
  
    ParsedAttrMap Names = getParsedAttrList(Records);
    for (const auto &I : Names) {
      OS << "PARSED_ATTR(" << I.first << ")\n";
    }
  }
  
  static bool isArgVariadic(const Record &R, StringRef AttrName) {
    return createArgument(R, AttrName)->isVariadic();
  }
  
  static void emitArgInfo(const Record &R, raw_ostream &OS) {
    // This function will count the number of arguments specified for the
    // attribute and emit the number of required arguments followed by the
    // number of optional arguments.
    std::vector<Record *> Args = R.getValueAsListOfDefs("Args");
    unsigned ArgCount = 0, OptCount = 0;
    bool HasVariadic = false;
    for (const auto *Arg : Args) {
      // If the arg is fake, it's the user's job to supply it: general parsing
      // logic shouldn't need to know anything about it.
      if (Arg->getValueAsBit("Fake"))
        continue;
      Arg->getValueAsBit("Optional") ? ++OptCount : ++ArgCount;
      if (!HasVariadic && isArgVariadic(*Arg, R.getName()))
        HasVariadic = true;
    }
  
    // If there is a variadic argument, we will set the optional argument count
    // to its largest value. Since it's currently a 4-bit number, we set it to 15.
    OS << "    NumArgs = " << ArgCount << ";\n";
    OS << "    OptArgs = " << (HasVariadic ? 15 : OptCount) << ";\n";
  }
  
  static std::string GetDiagnosticSpelling(const Record &R) {
    std::string Ret = std::string(R.getValueAsString("DiagSpelling"));
    if (!Ret.empty())
      return Ret;
  
    // If we couldn't find the DiagSpelling in this object, we can check to see
    // if the object is one that has a base, and if it is, loop up to the Base
    // member recursively.
    if (auto Base = R.getValueAsOptionalDef(BaseFieldName))
      return GetDiagnosticSpelling(*Base);
  
    return "";
  }
  
  static std::string CalculateDiagnostic(const Record &S) {
    // If the SubjectList object has a custom diagnostic associated with it,
    // return that directly.
    const StringRef CustomDiag = S.getValueAsString("CustomDiag");
    if (!CustomDiag.empty())
      return ("\"" + Twine(CustomDiag) + "\"").str();
  
    std::vector<std::string> DiagList;
    std::vector<Record *> Subjects = S.getValueAsListOfDefs("Subjects");
    for (const auto *Subject : Subjects) {
      const Record &R = *Subject;
      // Get the diagnostic text from the Decl or Stmt node given.
      std::string V = GetDiagnosticSpelling(R);
      if (V.empty()) {
        PrintError(R.getLoc(),
                   "Could not determine diagnostic spelling for the node: " +
                       R.getName() + "; please add one to DeclNodes.td");
      } else {
        // The node may contain a list of elements itself, so split the elements
        // by a comma, and trim any whitespace.
        SmallVector<StringRef, 2> Frags;
        llvm::SplitString(V, Frags, ",");
        for (auto Str : Frags) {
          DiagList.push_back(std::string(Str.trim()));
        }
      }
    }
  
    if (DiagList.empty()) {
      PrintFatalError(S.getLoc(),
                      "Could not deduce diagnostic argument for Attr subjects");
      return "";
    }
  
    // FIXME: this is not particularly good for localization purposes and ideally
    // should be part of the diagnostics engine itself with some sort of list
    // specifier.
  
    // A single member of the list can be returned directly.
    if (DiagList.size() == 1)
      return '"' + DiagList.front() + '"';
  
    if (DiagList.size() == 2)
      return '"' + DiagList[0] + " and " + DiagList[1] + '"';
  
    // If there are more than two in the list, we serialize the first N - 1
    // elements with a comma. This leaves the string in the state: foo, bar,
    // baz (but misses quux). We can then add ", and " for the last element
    // manually.
    std::string Diag = llvm::join(DiagList.begin(), DiagList.end() - 1, ", ");
    return '"' + Diag + ", and " + *(DiagList.end() - 1) + '"';
  }
  
  static std::string GetSubjectWithSuffix(const Record *R) {
    const std::string &B = std::string(R->getName());
    if (B == "DeclBase")
      return "Decl";
    return B + "Decl";
  }
  
  static std::string functionNameForCustomAppertainsTo(const Record &Subject) {
    return "is" + Subject.getName().str();
  }
  
  static void GenerateCustomAppertainsTo(const Record &Subject, raw_ostream &OS) {
    std::string FnName = functionNameForCustomAppertainsTo(Subject);
  
    // If this code has already been generated, we don't need to do anything.
    static std::set<std::string> CustomSubjectSet;
    auto I = CustomSubjectSet.find(FnName);
    if (I != CustomSubjectSet.end())
      return;
  
    // This only works with non-root Decls.
    Record *Base = Subject.getValueAsDef(BaseFieldName);
  
    // Not currently support custom subjects within custom subjects.
    if (Base->isSubClassOf("SubsetSubject")) {
      PrintFatalError(Subject.getLoc(),
                      "SubsetSubjects within SubsetSubjects is not supported");
      return;
    }
  
    OS << "static bool " << FnName << "(const Decl *D) {\n";
    OS << "  if (const auto *S = dyn_cast<";
    OS << GetSubjectWithSuffix(Base);
    OS << ">(D))\n";
    OS << "    return " << Subject.getValueAsString("CheckCode") << ";\n";
    OS << "  return false;\n";
    OS << "}\n\n";
  
    CustomSubjectSet.insert(FnName);
  }
  
  static void GenerateAppertainsTo(const Record &Attr, raw_ostream &OS) {
    // FIXME: this function only diagnoses declaration attributes and lacks
    // reasonable support for statement attributes.
  
    // If the attribute does not contain a Subjects definition, then use the
    // default appertainsTo logic.
    if (Attr.isValueUnset("Subjects"))
      return;
  
    const Record *SubjectObj = Attr.getValueAsDef("Subjects");
    std::vector<Record *> Subjects = SubjectObj->getValueAsListOfDefs("Subjects");
  
    // If the list of subjects is empty, it is assumed that the attribute
    // appertains to everything.
    if (Subjects.empty())
      return;
  
    bool Warn = SubjectObj->getValueAsDef("Diag")->getValueAsBit("Warn");
  
    // Split the subjects into declaration subjects and statement subjects.
    // FIXME: subset subjects are added to the declaration list until there are
    // enough statement attributes with custom subject needs to warrant
    // the implementation effort.
    std::vector<Record *> DeclSubjects, StmtSubjects;
    llvm::copy_if(
        Subjects, std::back_inserter(DeclSubjects), [](const Record *R) {
          return R->isSubClassOf("SubsetSubject") || !R->isSubClassOf("StmtNode");
        });
    llvm::copy_if(Subjects, std::back_inserter(StmtSubjects),
                  [](const Record *R) { return R->isSubClassOf("StmtNode"); });
  
    // We should have sorted all of the subjects into two lists.
    // FIXME: this assertion will be wrong if we ever add type attribute subjects.
    assert(DeclSubjects.size() + StmtSubjects.size() == Subjects.size());
  
    if (DeclSubjects.empty()) {
      // If there are no decl subjects but there are stmt subjects, diagnose
      // trying to apply a statement attribute to a declaration.
      if (!StmtSubjects.empty()) {
        OS << "bool diagAppertainsToDecl(Sema &S, const ParsedAttr &AL, ";
        OS << "const Decl *D) const override {\n";
        OS << "  S.Diag(AL.getLoc(), diag::err_stmt_attribute_invalid_on_decl)\n";
        OS << "    << AL << D->getLocation();\n";
        OS << "  return false;\n";
        OS << "}\n\n";
      }
    } else {
      // Otherwise, generate an appertainsTo check specific to this attribute
      // which checks all of the given subjects against the Decl passed in.
      OS << "bool diagAppertainsToDecl(Sema &S, ";
      OS << "const ParsedAttr &Attr, const Decl *D) const override {\n";
      OS << "  if (";
      for (auto I = DeclSubjects.begin(), E = DeclSubjects.end(); I != E; ++I) {
        // If the subject has custom code associated with it, use the generated
        // function for it. The function cannot be inlined into this check (yet)
        // because it requires the subject to be of a specific type, and were that
        // information inlined here, it would not support an attribute with
        // multiple custom subjects.
        if ((*I)->isSubClassOf("SubsetSubject"))
          OS << "!" << functionNameForCustomAppertainsTo(**I) << "(D)";
        else
          OS << "!isa<" << GetSubjectWithSuffix(*I) << ">(D)";
  
        if (I + 1 != E)
          OS << " && ";
      }
      OS << ") {\n";
      OS << "    S.Diag(Attr.getLoc(), diag::";
      OS << (Warn ? "warn_attribute_wrong_decl_type_str"
                  : "err_attribute_wrong_decl_type_str");
      OS << ")\n";
      OS << "      << Attr << ";
      OS << CalculateDiagnostic(*SubjectObj) << ";\n";
      OS << "    return false;\n";
      OS << "  }\n";
      OS << "  return true;\n";
      OS << "}\n\n";
    }
  
    if (StmtSubjects.empty()) {
      // If there are no stmt subjects but there are decl subjects, diagnose
      // trying to apply a declaration attribute to a statement.
      if (!DeclSubjects.empty()) {
        OS << "bool diagAppertainsToStmt(Sema &S, const ParsedAttr &AL, ";
        OS << "const Stmt *St) const override {\n";
        OS << "  S.Diag(AL.getLoc(), diag::err_decl_attribute_invalid_on_stmt)\n";
        OS << "    << AL << St->getBeginLoc();\n";
        OS << "  return false;\n";
        OS << "}\n\n";
      }
    } else {
      // Now, do the same for statements.
      OS << "bool diagAppertainsToStmt(Sema &S, ";
      OS << "const ParsedAttr &Attr, const Stmt *St) const override {\n";
      OS << "  if (";
      for (auto I = StmtSubjects.begin(), E = StmtSubjects.end(); I != E; ++I) {
        OS << "!isa<" << (*I)->getName() << ">(St)";
        if (I + 1 != E)
          OS << " && ";
      }
      OS << ") {\n";
      OS << "    S.Diag(Attr.getLoc(), diag::";
      OS << (Warn ? "warn_attribute_wrong_decl_type_str"
                  : "err_attribute_wrong_decl_type_str");
      OS << ")\n";
      OS << "      << Attr << ";
      OS << CalculateDiagnostic(*SubjectObj) << ";\n";
      OS << "    return false;\n";
      OS << "  }\n";
      OS << "  return true;\n";
      OS << "}\n\n";
    }
  }
  
  // Generates the mutual exclusion checks. The checks for parsed attributes are
  // written into OS and the checks for merging declaration attributes are
  // written into MergeOS.
  static void GenerateMutualExclusionsChecks(const Record &Attr,
                                             const RecordKeeper &Records,
                                             raw_ostream &OS,
                                             raw_ostream &MergeDeclOS,
                                             raw_ostream &MergeStmtOS) {
    // Find all of the definitions that inherit from MutualExclusions and include
    // the given attribute in the list of exclusions to generate the
    // diagMutualExclusion() check.
    std::vector<Record *> ExclusionsList =
        Records.getAllDerivedDefinitions("MutualExclusions");
  
    // We don't do any of this magic for type attributes yet.
    if (Attr.isSubClassOf("TypeAttr"))
      return;
  
    // This means the attribute is either a statement attribute, a decl
    // attribute, or both; find out which.
    bool CurAttrIsStmtAttr =
        Attr.isSubClassOf("StmtAttr") || Attr.isSubClassOf("DeclOrStmtAttr");
    bool CurAttrIsDeclAttr =
        !CurAttrIsStmtAttr || Attr.isSubClassOf("DeclOrStmtAttr");
  
    std::vector<std::string> DeclAttrs, StmtAttrs;
  
    for (const Record *Exclusion : ExclusionsList) {
      std::vector<Record *> MutuallyExclusiveAttrs =
          Exclusion->getValueAsListOfDefs("Exclusions");
      auto IsCurAttr = [Attr](const Record *R) {
        return R->getName() == Attr.getName();
      };
      if (llvm::any_of(MutuallyExclusiveAttrs, IsCurAttr)) {
        // This list of exclusions includes the attribute we're looking for, so
        // add the exclusive attributes to the proper list for checking.
        for (const Record *AttrToExclude : MutuallyExclusiveAttrs) {
          if (IsCurAttr(AttrToExclude))
            continue;
  
          if (CurAttrIsStmtAttr)
            StmtAttrs.push_back((AttrToExclude->getName() + "Attr").str());
          if (CurAttrIsDeclAttr)
            DeclAttrs.push_back((AttrToExclude->getName() + "Attr").str());
        }
      }
    }
  
    // If there are any decl or stmt attributes, silence -Woverloaded-virtual
    // warnings for them both.
    if (!DeclAttrs.empty() || !StmtAttrs.empty())
      OS << "  using ParsedAttrInfo::diagMutualExclusion;\n\n";
  
    // If we discovered any decl or stmt attributes to test for, generate the
    // predicates for them now.
    if (!DeclAttrs.empty()) {
      // Generate the ParsedAttrInfo subclass logic for declarations.
      OS << "  bool diagMutualExclusion(Sema &S, const ParsedAttr &AL, "
         << "const Decl *D) const override {\n";
      for (const std::string &A : DeclAttrs) {
        OS << "    if (const auto *A = D->getAttr<" << A << ">()) {\n";
        OS << "      S.Diag(AL.getLoc(), diag::err_attributes_are_not_compatible)"
           << " << AL << A;\n";
        OS << "      S.Diag(A->getLocation(), diag::note_conflicting_attribute);";
        OS << "      \nreturn false;\n";
        OS << "    }\n";
      }
      OS << "    return true;\n";
      OS << "  }\n\n";
  
      // Also generate the declaration attribute merging logic if the current
      // attribute is one that can be inheritted on a declaration. It is assumed
      // this code will be executed in the context of a function with parameters:
      // Sema &S, Decl *D, Attr *A and that returns a bool (false on diagnostic,
      // true on success).
      if (Attr.isSubClassOf("InheritableAttr")) {
        MergeDeclOS << "  if (const auto *Second = dyn_cast<"
                    << (Attr.getName() + "Attr").str() << ">(A)) {\n";
        for (const std::string &A : DeclAttrs) {
          MergeDeclOS << "    if (const auto *First = D->getAttr<" << A
                      << ">()) {\n";
          MergeDeclOS << "      S.Diag(First->getLocation(), "
                      << "diag::err_attributes_are_not_compatible) << First << "
                      << "Second;\n";
          MergeDeclOS << "      S.Diag(Second->getLocation(), "
                      << "diag::note_conflicting_attribute);\n";
          MergeDeclOS << "      return false;\n";
          MergeDeclOS << "    }\n";
        }
        MergeDeclOS << "    return true;\n";
        MergeDeclOS << "  }\n";
      }
    }
  
    // Statement attributes are a bit different from declarations. With
    // declarations, each attribute is added to the declaration as it is
    // processed, and so you can look on the Decl * itself to see if there is a
    // conflicting attribute. Statement attributes are processed as a group
    // because AttributedStmt needs to tail-allocate all of the attribute nodes
    // at once. This means we cannot check whether the statement already contains
    // an attribute to check for the conflict. Instead, we need to check whether
    // the given list of semantic attributes contain any conflicts. It is assumed
    // this code will be executed in the context of a function with parameters:
    // Sema &S, const SmallVectorImpl<const Attr *> &C. The code will be within a
    // loop which loops over the container C with a loop variable named A to
    // represent the current attribute to check for conflicts.
    //
    // FIXME: it would be nice not to walk over the list of potential attributes
    // to apply to the statement more than once, but statements typically don't
    // have long lists of attributes on them, so re-walking the list should not
    // be an expensive operation.
    if (!StmtAttrs.empty()) {
      MergeStmtOS << "    if (const auto *Second = dyn_cast<"
                  << (Attr.getName() + "Attr").str() << ">(A)) {\n";
      MergeStmtOS << "      auto Iter = llvm::find_if(C, [](const Attr *Check) "
                  << "{ return isa<";
      interleave(
          StmtAttrs, [&](const std::string &Name) { MergeStmtOS << Name; },
          [&] { MergeStmtOS << ", "; });
      MergeStmtOS << ">(Check); });\n";
      MergeStmtOS << "      if (Iter != C.end()) {\n";
      MergeStmtOS << "        S.Diag((*Iter)->getLocation(), "
                  << "diag::err_attributes_are_not_compatible) << *Iter << "
                  << "Second;\n";
      MergeStmtOS << "        S.Diag(Second->getLocation(), "
                  << "diag::note_conflicting_attribute);\n";
      MergeStmtOS << "        return false;\n";
      MergeStmtOS << "      }\n";
      MergeStmtOS << "    }\n";
    }
  }
  
  static void
  emitAttributeMatchRules(PragmaClangAttributeSupport &PragmaAttributeSupport,
                          raw_ostream &OS) {
    OS << "static bool checkAttributeMatchRuleAppliesTo(const Decl *D, "
       << AttributeSubjectMatchRule::EnumName << " rule) {\n";
    OS << "  switch (rule) {\n";
    for (const auto &Rule : PragmaAttributeSupport.Rules) {
      if (Rule.isAbstractRule()) {
        OS << "  case " << Rule.getEnumValue() << ":\n";
        OS << "    assert(false && \"Abstract matcher rule isn't allowed\");\n";
        OS << "    return false;\n";
        continue;
      }
      std::vector<Record *> Subjects = Rule.getSubjects();
      assert(!Subjects.empty() && "Missing subjects");
      OS << "  case " << Rule.getEnumValue() << ":\n";
      OS << "    return ";
      for (auto I = Subjects.begin(), E = Subjects.end(); I != E; ++I) {
        // If the subject has custom code associated with it, use the function
        // that was generated for GenerateAppertainsTo to check if the declaration
        // is valid.
        if ((*I)->isSubClassOf("SubsetSubject"))
          OS << functionNameForCustomAppertainsTo(**I) << "(D)";
        else
          OS << "isa<" << GetSubjectWithSuffix(*I) << ">(D)";
  
        if (I + 1 != E)
          OS << " || ";
      }
      OS << ";\n";
    }
    OS << "  }\n";
    OS << "  llvm_unreachable(\"Invalid match rule\");\nreturn false;\n";
    OS << "}\n\n";
  }
  
  static void GenerateLangOptRequirements(const Record &R,
                                          raw_ostream &OS) {
    // If the attribute has an empty or unset list of language requirements,
    // use the default handler.
    std::vector<Record *> LangOpts = R.getValueAsListOfDefs("LangOpts");
    if (LangOpts.empty())
      return;
  
    OS << "bool acceptsLangOpts(const LangOptions &LangOpts) const override {\n";
    OS << "  if (" << GenerateTestExpression(LangOpts, true) << ")\n";
    OS << "    return true;\n\n";
    OS << "  return !" << GenerateTestExpression(LangOpts, false) << ";\n";
    OS << "}\n\n";
  }
  
  static void GenerateTargetRequirements(const Record &Attr,
                                         const ParsedAttrMap &Dupes,
                                         raw_ostream &OS) {
    // If the attribute is not a target specific attribute, use the default
    // target handler.
    if (!Attr.isSubClassOf("TargetSpecificAttr"))
      return;
  
    // Get the list of architectures to be tested for.
    const Record *R = Attr.getValueAsDef("Target");
    std::vector<StringRef> Arches = R->getValueAsListOfStrings("Arches");
  
    // If there are other attributes which share the same parsed attribute kind,
    // such as target-specific attributes with a shared spelling, collapse the
    // duplicate architectures. This is required because a shared target-specific
    // attribute has only one ParsedAttr::Kind enumeration value, but it
    // applies to multiple target architectures. In order for the attribute to be
    // considered valid, all of its architectures need to be included.
    if (!Attr.isValueUnset("ParseKind")) {
      const StringRef APK = Attr.getValueAsString("ParseKind");
      for (const auto &I : Dupes) {
        if (I.first == APK) {
          std::vector<StringRef> DA =
              I.second->getValueAsDef("Target")->getValueAsListOfStrings(
                  "Arches");
          Arches.insert(Arches.end(), DA.begin(), DA.end());
        }
      }
    }
  
    std::string FnName = "isTarget";
    std::string Test;
    bool UsesT = GenerateTargetSpecificAttrChecks(R, Arches, Test, &FnName);
  
    OS << "bool existsInTarget(const TargetInfo &Target) const override {\n";
    if (UsesT)
      OS << "  const llvm::Triple &T = Target.getTriple(); (void)T;\n";
    OS << "  return " << Test << ";\n";
    OS << "}\n\n";
  }
  
  static void GenerateSpellingIndexToSemanticSpelling(const Record &Attr,
                                                      raw_ostream &OS) {
    // If the attribute does not have a semantic form, we can bail out early.
    if (!Attr.getValueAsBit("ASTNode"))
      return;
  
    std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(Attr);
  
    // If there are zero or one spellings, or all of the spellings share the same
    // name, we can also bail out early.
    if (Spellings.size() <= 1 || SpellingNamesAreCommon(Spellings))
      return;
  
    // Generate the enumeration we will use for the mapping.
    SemanticSpellingMap SemanticToSyntacticMap;
    std::string Enum = CreateSemanticSpellings(Spellings, SemanticToSyntacticMap);
    std::string Name = Attr.getName().str() + "AttrSpellingMap";
  
    OS << "unsigned spellingIndexToSemanticSpelling(";
    OS << "const ParsedAttr &Attr) const override {\n";
    OS << Enum;
    OS << "  unsigned Idx = Attr.getAttributeSpellingListIndex();\n";
    WriteSemanticSpellingSwitch("Idx", SemanticToSyntacticMap, OS);
    OS << "}\n\n";
  }
  
  static void GenerateHandleDeclAttribute(const Record &Attr, raw_ostream &OS) {
    // Only generate if Attr can be handled simply.
    if (!Attr.getValueAsBit("SimpleHandler"))
      return;
  
    // Generate a function which just converts from ParsedAttr to the Attr type.
    OS << "AttrHandling handleDeclAttribute(Sema &S, Decl *D,";
    OS << "const ParsedAttr &Attr) const override {\n";
    OS << "  D->addAttr(::new (S.Context) " << Attr.getName();
    OS << "Attr(S.Context, Attr));\n";
    OS << "  return AttributeApplied;\n";
    OS << "}\n\n";
  }
  
  static bool IsKnownToGCC(const Record &Attr) {
    // Look at the spellings for this subject; if there are any spellings which
    // claim to be known to GCC, the attribute is known to GCC.
    return llvm::any_of(
        GetFlattenedSpellings(Attr),
        [](const FlattenedSpelling &S) { return S.knownToGCC(); });
  }
  
  /// Emits the parsed attribute helpers
  void EmitClangAttrParsedAttrImpl(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Parsed attribute helpers", OS);
  
    OS << "#if !defined(WANT_DECL_MERGE_LOGIC) && "
       << "!defined(WANT_STMT_MERGE_LOGIC)\n";
    PragmaClangAttributeSupport &PragmaAttributeSupport =
        getPragmaAttributeSupport(Records);
  
    // Get the list of parsed attributes, and accept the optional list of
    // duplicates due to the ParseKind.
    ParsedAttrMap Dupes;
    ParsedAttrMap Attrs = getParsedAttrList(Records, &Dupes);
  
    // Generate all of the custom appertainsTo functions that the attributes
    // will be using.
    for (auto I : Attrs) {
      const Record &Attr = *I.second;
      if (Attr.isValueUnset("Subjects"))
        continue;
      const Record *SubjectObj = Attr.getValueAsDef("Subjects");
      for (auto Subject : SubjectObj->getValueAsListOfDefs("Subjects"))
        if (Subject->isSubClassOf("SubsetSubject"))
          GenerateCustomAppertainsTo(*Subject, OS);
    }
  
    // This stream is used to collect all of the declaration attribute merging
    // logic for performing mutual exclusion checks. This gets emitted at the
    // end of the file in a helper function of its own.
    std::string DeclMergeChecks, StmtMergeChecks;
    raw_string_ostream MergeDeclOS(DeclMergeChecks), MergeStmtOS(StmtMergeChecks);
  
    // Generate a ParsedAttrInfo struct for each of the attributes.
    for (auto I = Attrs.begin(), E = Attrs.end(); I != E; ++I) {
      // TODO: If the attribute's kind appears in the list of duplicates, that is
      // because it is a target-specific attribute that appears multiple times.
      // It would be beneficial to test whether the duplicates are "similar
      // enough" to each other to not cause problems. For instance, check that
      // the spellings are identical, and custom parsing rules match, etc.
  
      // We need to generate struct instances based off ParsedAttrInfo from
      // ParsedAttr.cpp.
      const std::string &AttrName = I->first;
      const Record &Attr = *I->second;
      auto Spellings = GetFlattenedSpellings(Attr);
      if (!Spellings.empty()) {
        OS << "static constexpr ParsedAttrInfo::Spelling " << I->first
           << "Spellings[] = {\n";
        for (const auto &S : Spellings) {
          const std::string &RawSpelling = S.name();
          std::string Spelling;
          if (!S.nameSpace().empty())
            Spelling += S.nameSpace() + "::";
          if (S.variety() == "GNU")
            Spelling += NormalizeGNUAttrSpelling(RawSpelling);
          else
            Spelling += RawSpelling;
          OS << "  {AttributeCommonInfo::AS_" << S.variety();
          OS << ", \"" << Spelling << "\"},\n";
        }
        OS << "};\n";
      }
  
      std::vector<std::string> ArgNames;
      for (const auto &Arg : Attr.getValueAsListOfDefs("Args")) {
        bool UnusedUnset;
        if (Arg->getValueAsBitOrUnset("Fake", UnusedUnset))
          continue;
        ArgNames.push_back(Arg->getValueAsString("Name").str());
        for (const auto &Class : Arg->getSuperClasses()) {
          if (Class.first->getName().startswith("Variadic")) {
            ArgNames.back().append("...");
            break;
          }
        }
      }
      if (!ArgNames.empty()) {
        OS << "static constexpr const char *" << I->first << "ArgNames[] = {\n";
        for (const auto &N : ArgNames)
          OS << '"' << N << "\",";
        OS << "};\n";
      }
  
      OS << "struct ParsedAttrInfo" << I->first
         << " final : public ParsedAttrInfo {\n";
      OS << "  ParsedAttrInfo" << I->first << "() {\n";
      OS << "    AttrKind = ParsedAttr::AT_" << AttrName << ";\n";
      emitArgInfo(Attr, OS);
      OS << "    HasCustomParsing = ";
      OS << Attr.getValueAsBit("HasCustomParsing") << ";\n";
      OS << "    IsTargetSpecific = ";
      OS << Attr.isSubClassOf("TargetSpecificAttr") << ";\n";
      OS << "    IsType = ";
      OS << (Attr.isSubClassOf("TypeAttr") ||
             Attr.isSubClassOf("DeclOrTypeAttr")) << ";\n";
      OS << "    IsStmt = ";
      OS << (Attr.isSubClassOf("StmtAttr") || Attr.isSubClassOf("DeclOrStmtAttr"))
         << ";\n";
      OS << "    IsKnownToGCC = ";
      OS << IsKnownToGCC(Attr) << ";\n";
      OS << "    IsSupportedByPragmaAttribute = ";
      OS << PragmaAttributeSupport.isAttributedSupported(*I->second) << ";\n";
      OS << "    SupportsNonconformingLambdaSyntax = ";
      OS << Attr.getValueAsBit("SupportsNonconformingLambdaSyntax") << ";\n";
      if (!Spellings.empty())
        OS << "    Spellings = " << I->first << "Spellings;\n";
      if (!ArgNames.empty())
        OS << "    ArgNames = " << I->first << "ArgNames;\n";
      OS << "  }\n";
      GenerateAppertainsTo(Attr, OS);
      GenerateMutualExclusionsChecks(Attr, Records, OS, MergeDeclOS, MergeStmtOS);
      GenerateLangOptRequirements(Attr, OS);
      GenerateTargetRequirements(Attr, Dupes, OS);
      GenerateSpellingIndexToSemanticSpelling(Attr, OS);
      PragmaAttributeSupport.generateStrictConformsTo(*I->second, OS);
      GenerateHandleDeclAttribute(Attr, OS);
      OS << "static const ParsedAttrInfo" << I->first << " Instance;\n";
      OS << "};\n";
      OS << "const ParsedAttrInfo" << I->first << " ParsedAttrInfo" << I->first
         << "::Instance;\n";
    }
  
    OS << "static const ParsedAttrInfo *AttrInfoMap[] = {\n";
    for (auto I = Attrs.begin(), E = Attrs.end(); I != E; ++I) {
      OS << "&ParsedAttrInfo" << I->first << "::Instance,\n";
    }
    OS << "};\n\n";
  
    // Generate the attribute match rules.
    emitAttributeMatchRules(PragmaAttributeSupport, OS);
  
    OS << "#elif defined(WANT_DECL_MERGE_LOGIC)\n\n";
  
    // Write out the declaration merging check logic.
    OS << "static bool DiagnoseMutualExclusions(Sema &S, const NamedDecl *D, "
       << "const Attr *A) {\n";
    OS << MergeDeclOS.str();
    OS << "  return true;\n";
    OS << "}\n\n";
  
    OS << "#elif defined(WANT_STMT_MERGE_LOGIC)\n\n";
  
    // Write out the statement merging check logic.
    OS << "static bool DiagnoseMutualExclusions(Sema &S, "
       << "const SmallVectorImpl<const Attr *> &C) {\n";
    OS << "  for (const Attr *A : C) {\n";
    OS << MergeStmtOS.str();
    OS << "  }\n";
    OS << "  return true;\n";
    OS << "}\n\n";
  
    OS << "#endif\n";
  }
  
  // Emits the kind list of parsed attributes
  void EmitClangAttrParsedAttrKinds(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Attribute name matcher", OS);
  
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    std::vector<StringMatcher::StringPair> GNU, Declspec, Microsoft, CXX11,
        Keywords, Pragma, C2x;
    std::set<std::string> Seen;
    for (const auto *A : Attrs) {
      const Record &Attr = *A;
  
      bool SemaHandler = Attr.getValueAsBit("SemaHandler");
      bool Ignored = Attr.getValueAsBit("Ignored");
      if (SemaHandler || Ignored) {
        // Attribute spellings can be shared between target-specific attributes,
        // and can be shared between syntaxes for the same attribute. For
        // instance, an attribute can be spelled GNU<"interrupt"> for an ARM-
        // specific attribute, or MSP430-specific attribute. Additionally, an
        // attribute can be spelled GNU<"dllexport"> and Declspec<"dllexport">
        // for the same semantic attribute. Ultimately, we need to map each of
        // these to a single AttributeCommonInfo::Kind value, but the
        // StringMatcher class cannot handle duplicate match strings. So we
        // generate a list of string to match based on the syntax, and emit
        // multiple string matchers depending on the syntax used.
        std::string AttrName;
        if (Attr.isSubClassOf("TargetSpecificAttr") &&
            !Attr.isValueUnset("ParseKind")) {
          AttrName = std::string(Attr.getValueAsString("ParseKind"));
          if (Seen.find(AttrName) != Seen.end())
            continue;
          Seen.insert(AttrName);
        } else
          AttrName = NormalizeAttrName(StringRef(Attr.getName())).str();
  
        std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(Attr);
        for (const auto &S : Spellings) {
          const std::string &RawSpelling = S.name();
          std::vector<StringMatcher::StringPair> *Matches = nullptr;
          std::string Spelling;
          const std::string &Variety = S.variety();
          if (Variety == "CXX11") {
            Matches = &CXX11;
            if (!S.nameSpace().empty())
              Spelling += S.nameSpace() + "::";
          } else if (Variety == "C2x") {
            Matches = &C2x;
            if (!S.nameSpace().empty())
              Spelling += S.nameSpace() + "::";
          } else if (Variety == "GNU")
            Matches = &GNU;
          else if (Variety == "Declspec")
            Matches = &Declspec;
          else if (Variety == "Microsoft")
            Matches = &Microsoft;
          else if (Variety == "Keyword")
            Matches = &Keywords;
          else if (Variety == "Pragma")
            Matches = &Pragma;
  
          assert(Matches && "Unsupported spelling variety found");
  
          if (Variety == "GNU")
            Spelling += NormalizeGNUAttrSpelling(RawSpelling);
          else
            Spelling += RawSpelling;
  
          if (SemaHandler)
            Matches->push_back(StringMatcher::StringPair(
                Spelling, "return AttributeCommonInfo::AT_" + AttrName + ";"));
          else
            Matches->push_back(StringMatcher::StringPair(
                Spelling, "return AttributeCommonInfo::IgnoredAttribute;"));
        }
      }
    }
  
    OS << "static AttributeCommonInfo::Kind getAttrKind(StringRef Name, ";
    OS << "AttributeCommonInfo::Syntax Syntax) {\n";
    OS << "  if (AttributeCommonInfo::AS_GNU == Syntax) {\n";
    StringMatcher("Name", GNU, OS).Emit();
    OS << "  } else if (AttributeCommonInfo::AS_Declspec == Syntax) {\n";
    StringMatcher("Name", Declspec, OS).Emit();
    OS << "  } else if (AttributeCommonInfo::AS_Microsoft == Syntax) {\n";
    StringMatcher("Name", Microsoft, OS).Emit();
    OS << "  } else if (AttributeCommonInfo::AS_CXX11 == Syntax) {\n";
    StringMatcher("Name", CXX11, OS).Emit();
    OS << "  } else if (AttributeCommonInfo::AS_C2x == Syntax) {\n";
    StringMatcher("Name", C2x, OS).Emit();
    OS << "  } else if (AttributeCommonInfo::AS_Keyword == Syntax || ";
    OS << "AttributeCommonInfo::AS_ContextSensitiveKeyword == Syntax) {\n";
    StringMatcher("Name", Keywords, OS).Emit();
    OS << "  } else if (AttributeCommonInfo::AS_Pragma == Syntax) {\n";
    StringMatcher("Name", Pragma, OS).Emit();
    OS << "  }\n";
    OS << "  return AttributeCommonInfo::UnknownAttribute;\n"
       << "}\n";
  }
  
  // Emits the code to dump an attribute.
  void EmitClangAttrTextNodeDump(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Attribute text node dumper", OS);
  
    std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr"), Args;
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
  
      // If the attribute has a semantically-meaningful name (which is determined
      // by whether there is a Spelling enumeration for it), then write out the
      // spelling used for the attribute.
  
      std::string FunctionContent;
      llvm::raw_string_ostream SS(FunctionContent);
  
      std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(R);
      if (Spellings.size() > 1 && !SpellingNamesAreCommon(Spellings))
        SS << "    OS << \" \" << A->getSpelling();\n";
  
      Args = R.getValueAsListOfDefs("Args");
      for (const auto *Arg : Args)
        createArgument(*Arg, R.getName())->writeDump(SS);
  
      if (SS.tell()) {
        OS << "  void Visit" << R.getName() << "Attr(const " << R.getName()
           << "Attr *A) {\n";
        if (!Args.empty())
          OS << "    const auto *SA = cast<" << R.getName()
             << "Attr>(A); (void)SA;\n";
        OS << SS.str();
        OS << "  }\n";
      }
    }
  }
  
  void EmitClangAttrNodeTraverse(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Attribute text node traverser", OS);
  
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr"), Args;
    for (const auto *Attr : Attrs) {
      const Record &R = *Attr;
      if (!R.getValueAsBit("ASTNode"))
        continue;
  
      std::string FunctionContent;
      llvm::raw_string_ostream SS(FunctionContent);
  
      Args = R.getValueAsListOfDefs("Args");
      for (const auto *Arg : Args)
        createArgument(*Arg, R.getName())->writeDumpChildren(SS);
      if (SS.tell()) {
        OS << "  void Visit" << R.getName() << "Attr(const " << R.getName()
           << "Attr *A) {\n";
        if (!Args.empty())
          OS << "    const auto *SA = cast<" << R.getName()
             << "Attr>(A); (void)SA;\n";
        OS << SS.str();
        OS << "  }\n";
      }
    }
  }
  
  void EmitClangAttrParserStringSwitches(RecordKeeper &Records,
                                         raw_ostream &OS) {
    emitSourceFileHeader("Parser-related llvm::StringSwitch cases", OS);
    emitClangAttrArgContextList(Records, OS);
    emitClangAttrIdentifierArgList(Records, OS);
    emitClangAttrVariadicIdentifierArgList(Records, OS);
    emitClangAttrThisIsaIdentifierArgList(Records, OS);
    emitClangAttrTypeArgList(Records, OS);
    emitClangAttrLateParsedList(Records, OS);
  }
  
  void EmitClangAttrSubjectMatchRulesParserStringSwitches(RecordKeeper &Records,
                                                          raw_ostream &OS) {
    getPragmaAttributeSupport(Records).generateParsingHelpers(OS);
  }
  
  void EmitClangAttrDocTable(RecordKeeper &Records, raw_ostream &OS) {
    emitSourceFileHeader("Clang attribute documentation", OS);
  
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    for (const auto *A : Attrs) {
      if (!A->getValueAsBit("ASTNode"))
        continue;
      std::vector<Record *> Docs = A->getValueAsListOfDefs("Documentation");
      assert(!Docs.empty());
      // Only look at the first documentation if there are several.
      // (Currently there's only one such attr, revisit if this becomes common).
      StringRef Text =
          Docs.front()->getValueAsOptionalString("Content").getValueOr("");
      OS << "\nstatic const char AttrDoc_" << A->getName() << "[] = "
         << "R\"reST(" << Text.trim() << ")reST\";\n";
    }
  }
  
  enum class SpellingKind {
    GNU,
    CXX11,
    C2x,
    Declspec,
    Microsoft,
    Keyword,
    Pragma,
  };
  static const size_t NumSpellingKinds = (size_t)SpellingKind::Pragma + 1;
  
  class SpellingList {
    std::vector<std::string> Spellings[NumSpellingKinds];
  
  public:
    ArrayRef<std::string> operator[](SpellingKind K) const {
      return Spellings[(size_t)K];
    }
  
    void add(const Record &Attr, FlattenedSpelling Spelling) {
      SpellingKind Kind = StringSwitch<SpellingKind>(Spelling.variety())
                              .Case("GNU", SpellingKind::GNU)
                              .Case("CXX11", SpellingKind::CXX11)
                              .Case("C2x", SpellingKind::C2x)
                              .Case("Declspec", SpellingKind::Declspec)
                              .Case("Microsoft", SpellingKind::Microsoft)
                              .Case("Keyword", SpellingKind::Keyword)
                              .Case("Pragma", SpellingKind::Pragma);
      std::string Name;
      if (!Spelling.nameSpace().empty()) {
        switch (Kind) {
        case SpellingKind::CXX11:
        case SpellingKind::C2x:
          Name = Spelling.nameSpace() + "::";
          break;
        case SpellingKind::Pragma:
          Name = Spelling.nameSpace() + " ";
          break;
        default:
          PrintFatalError(Attr.getLoc(), "Unexpected namespace in spelling");
        }
      }
      Name += Spelling.name();
  
      Spellings[(size_t)Kind].push_back(Name);
    }
  };
  
  class DocumentationData {
  public:
    const Record *Documentation;
    const Record *Attribute;
    std::string Heading;
    SpellingList SupportedSpellings;
  
    DocumentationData(const Record &Documentation, const Record &Attribute,
                      std::pair<std::string, SpellingList> HeadingAndSpellings)
        : Documentation(&Documentation), Attribute(&Attribute),
          Heading(std::move(HeadingAndSpellings.first)),
          SupportedSpellings(std::move(HeadingAndSpellings.second)) {}
  };
  
  static void WriteCategoryHeader(const Record *DocCategory,
                                  raw_ostream &OS) {
    const StringRef Name = DocCategory->getValueAsString("Name");
    OS << Name << "\n" << std::string(Name.size(), '=') << "\n";
  
    // If there is content, print that as well.
    const StringRef ContentStr = DocCategory->getValueAsString("Content");
    // Trim leading and trailing newlines and spaces.
    OS << ContentStr.trim();
  
    OS << "\n\n";
  }
  
  static std::pair<std::string, SpellingList>
  GetAttributeHeadingAndSpellings(const Record &Documentation,
                                  const Record &Attribute) {
    // FIXME: there is no way to have a per-spelling category for the attribute
    // documentation. This may not be a limiting factor since the spellings
    // should generally be consistently applied across the category.
  
    std::vector<FlattenedSpelling> Spellings = GetFlattenedSpellings(Attribute);
    if (Spellings.empty())
      PrintFatalError(Attribute.getLoc(),
                      "Attribute has no supported spellings; cannot be "
                      "documented");
  
    // Determine the heading to be used for this attribute.
    std::string Heading = std::string(Documentation.getValueAsString("Heading"));
    if (Heading.empty()) {
      // If there's only one spelling, we can simply use that.
      if (Spellings.size() == 1)
        Heading = Spellings.begin()->name();
      else {
        std::set<std::string> Uniques;
        for (auto I = Spellings.begin(), E = Spellings.end();
             I != E && Uniques.size() <= 1; ++I) {
          std::string Spelling =
              std::string(NormalizeNameForSpellingComparison(I->name()));
          Uniques.insert(Spelling);
        }
        // If the semantic map has only one spelling, that is sufficient for our
        // needs.
        if (Uniques.size() == 1)
          Heading = *Uniques.begin();
      }
    }
  
    // If the heading is still empty, it is an error.
    if (Heading.empty())
      PrintFatalError(Attribute.getLoc(),
                      "This attribute requires a heading to be specified");
  
    SpellingList SupportedSpellings;
    for (const auto &I : Spellings)
      SupportedSpellings.add(Attribute, I);
  
    return std::make_pair(std::move(Heading), std::move(SupportedSpellings));
  }
  
  static void WriteDocumentation(RecordKeeper &Records,
                                 const DocumentationData &Doc, raw_ostream &OS) {
    OS << Doc.Heading << "\n" << std::string(Doc.Heading.length(), '-') << "\n";
  
    // List what spelling syntaxes the attribute supports.
    OS << ".. csv-table:: Supported Syntaxes\n";
    OS << "   :header: \"GNU\", \"C++11\", \"C2x\", \"``__declspec``\",";
    OS << " \"Keyword\", \"``#pragma``\", \"``#pragma clang attribute``\"\n\n";
    OS << "   \"";
    for (size_t Kind = 0; Kind != NumSpellingKinds; ++Kind) {
      SpellingKind K = (SpellingKind)Kind;
      // TODO: List Microsoft (IDL-style attribute) spellings once we fully
      // support them.
      if (K == SpellingKind::Microsoft)
        continue;
  
      bool PrintedAny = false;
      for (StringRef Spelling : Doc.SupportedSpellings[K]) {
        if (PrintedAny)
          OS << " |br| ";
        OS << "``" << Spelling << "``";
        PrintedAny = true;
      }
  
      OS << "\",\"";
    }
  
    if (getPragmaAttributeSupport(Records).isAttributedSupported(
            *Doc.Attribute))
      OS << "Yes";
    OS << "\"\n\n";
  
    // If the attribute is deprecated, print a message about it, and possibly
    // provide a replacement attribute.
    if (!Doc.Documentation->isValueUnset("Deprecated")) {
      OS << "This attribute has been deprecated, and may be removed in a future "
         << "version of Clang.";
      const Record &Deprecated = *Doc.Documentation->getValueAsDef("Deprecated");
      const StringRef Replacement = Deprecated.getValueAsString("Replacement");
      if (!Replacement.empty())
        OS << "  This attribute has been superseded by ``" << Replacement
           << "``.";
      OS << "\n\n";
    }
  
    const StringRef ContentStr = Doc.Documentation->getValueAsString("Content");
    // Trim leading and trailing newlines and spaces.
    OS << ContentStr.trim();
  
    OS << "\n\n\n";
  }
  
  void EmitClangAttrDocs(RecordKeeper &Records, raw_ostream &OS) {
    // Get the documentation introduction paragraph.
    const Record *Documentation = Records.getDef("GlobalDocumentation");
    if (!Documentation) {
      PrintFatalError("The Documentation top-level definition is missing, "
                      "no documentation will be generated.");
      return;
    }
  
    OS << Documentation->getValueAsString("Intro") << "\n";
  
    // Gather the Documentation lists from each of the attributes, based on the
    // category provided.
    std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
    std::map<const Record *, std::vector<DocumentationData>> SplitDocs;
    for (const auto *A : Attrs) {
      const Record &Attr = *A;
      std::vector<Record *> Docs = Attr.getValueAsListOfDefs("Documentation");
      for (const auto *D : Docs) {
        const Record &Doc = *D;
        const Record *Category = Doc.getValueAsDef("Category");
        // If the category is "undocumented", then there cannot be any other
        // documentation categories (otherwise, the attribute would become
        // documented).
        const StringRef Cat = Category->getValueAsString("Name");
        bool Undocumented = Cat == "Undocumented";
        if (Undocumented && Docs.size() > 1)
          PrintFatalError(Doc.getLoc(),
                          "Attribute is \"Undocumented\", but has multiple "
                          "documentation categories");
  
        if (!Undocumented)
          SplitDocs[Category].push_back(DocumentationData(
              Doc, Attr, GetAttributeHeadingAndSpellings(Doc, Attr)));
      }
    }
  
    // Having split the attributes out based on what documentation goes where,
    // we can begin to generate sections of documentation.
    for (auto &I : SplitDocs) {
      WriteCategoryHeader(I.first, OS);
  
      llvm::sort(I.second,
                 [](const DocumentationData &D1, const DocumentationData &D2) {
                   return D1.Heading < D2.Heading;
                 });
  
      // Walk over each of the attributes in the category and write out their
      // documentation.
      for (const auto &Doc : I.second)
        WriteDocumentation(Records, Doc, OS);
    }
  }
  
  void EmitTestPragmaAttributeSupportedAttributes(RecordKeeper &Records,
                                                  raw_ostream &OS) {
    PragmaClangAttributeSupport Support = getPragmaAttributeSupport(Records);
    ParsedAttrMap Attrs = getParsedAttrList(Records);
    OS << "#pragma clang attribute supports the following attributes:\n";
    for (const auto &I : Attrs) {
      if (!Support.isAttributedSupported(*I.second))
        continue;
      OS << I.first;
      if (I.second->isValueUnset("Subjects")) {
        OS << " ()\n";
        continue;
      }
      const Record *SubjectObj = I.second->getValueAsDef("Subjects");
      std::vector<Record *> Subjects =
          SubjectObj->getValueAsListOfDefs("Subjects");
      OS << " (";
      bool PrintComma = false;
      for (const auto &Subject : llvm::enumerate(Subjects)) {
        if (!isSupportedPragmaClangAttributeSubject(*Subject.value()))
          continue;
        if (PrintComma)
          OS << ", ";
        PrintComma = true;
        PragmaClangAttributeSupport::RuleOrAggregateRuleSet &RuleSet =
            Support.SubjectsToRules.find(Subject.value())->getSecond();
        if (RuleSet.isRule()) {
          OS << RuleSet.getRule().getEnumValueName();
          continue;
        }
        OS << "(";
        for (const auto &Rule : llvm::enumerate(RuleSet.getAggregateRuleSet())) {
          if (Rule.index())
            OS << ", ";
          OS << Rule.value().getEnumValueName();
        }
        OS << ")";
      }
      OS << ")\n";
    }
    OS << "End of supported attributes.\n";
  }
  
  } // end namespace clang
  