C++ ASTContext::getLangOpts方法代码示例

    /// HandleTagDeclDefinition - This callback is invoked each time a TagDecl
    /// to (e.g. struct, union, enum, class) is completed. This allows the
    /// client hack on the type, which can occur at any point in the file
    /// (because these can be defined in declspecs).
    void HandleTagDeclDefinition(TagDecl *D) override {
      if (Diags.hasErrorOccurred())
        return;

      Builder->UpdateCompletedType(D);

      // For MSVC compatibility, treat declarations of static data members with
      // inline initializers as definitions.
      if (Ctx->getLangOpts().MSVCCompat) {
        for (Decl *Member : D->decls()) {
          if (VarDecl *VD = dyn_cast<VarDecl>(Member)) {
            if (Ctx->isMSStaticDataMemberInlineDefinition(VD) &&
                Ctx->DeclMustBeEmitted(VD)) {
              Builder->EmitGlobal(VD);
            }
          }
        }
      }
    }

static void printSourceRange(CharSourceRange range, ASTContext &Ctx,
                             raw_ostream &OS) {
  SourceManager &SM = Ctx.getSourceManager();
  const LangOptions &langOpts = Ctx.getLangOpts();

  PresumedLoc PL = SM.getPresumedLoc(range.getBegin());

  OS << llvm::sys::path::filename(PL.getFilename());
  OS << " [" << PL.getLine() << ":"
             << PL.getColumn();
  OS << " - ";

  SourceLocation end = range.getEnd();
  PL = SM.getPresumedLoc(end);

  unsigned endCol = PL.getColumn() - 1;
  if (!range.isTokenRange())
    endCol += Lexer::MeasureTokenLength(end, SM, langOpts);
  OS << PL.getLine() << ":" << endCol << "]";
}

void UnnecessaryValueParamCheck::handleMoveFix(const ParmVarDecl &Var,
                                               const DeclRefExpr &CopyArgument,
                                               const ASTContext &Context) {
  auto Diag = diag(CopyArgument.getLocStart(),
                   "parameter %0 is passed by value and only copied once; "
                   "consider moving it to avoid unnecessary copies")
              << &Var;
  // Do not propose fixes in macros since we cannot place them correctly.
  if (CopyArgument.getLocStart().isMacroID())
    return;
  const auto &SM = Context.getSourceManager();
  auto EndLoc = Lexer::getLocForEndOfToken(CopyArgument.getLocation(), 0, SM,
                                           Context.getLangOpts());
  Diag << FixItHint::CreateInsertion(CopyArgument.getLocStart(), "std::move(")
       << FixItHint::CreateInsertion(EndLoc, ")");
  if (auto IncludeFixit = Inserter->CreateIncludeInsertion(
          SM.getFileID(CopyArgument.getLocStart()), "utility",
          /*IsAngled=*/true))
    Diag << *IncludeFixit;
}

static Cl::Kinds ClassifyConditional(ASTContext &Ctx, const Expr *True,
                                     const Expr *False) {
  assert(Ctx.getLangOpts().CPlusPlus &&
         "This is only relevant for C++.");

  // C++ [expr.cond]p2
  //   If either the second or the third operand has type (cv) void, [...]
  //   the result [...] is a prvalue.
  if (True->getType()->isVoidType() || False->getType()->isVoidType())
    return Cl::CL_PRValue;

  // Note that at this point, we have already performed all conversions
  // according to [expr.cond]p3.
  // C++ [expr.cond]p4: If the second and third operands are glvalues of the
  //   same value category [...], the result is of that [...] value category.
  // C++ [expr.cond]p5: Otherwise, the result is a prvalue.
  Cl::Kinds LCl = ClassifyInternal(Ctx, True),
            RCl = ClassifyInternal(Ctx, False);
  return LCl == RCl ? LCl : Cl::CL_PRValue;
}

// Checks if 'typedef' keyword can be removed - we do it only if
// it is the only declaration in a declaration chain.
static bool CheckRemoval(SourceManager &SM, const SourceLocation &LocStart,
                         const SourceLocation &LocEnd, ASTContext &Context,
                         SourceRange &ResultRange) {
  FileID FID = SM.getFileID(LocEnd);
  llvm::MemoryBuffer *Buffer = SM.getBuffer(FID, LocEnd);
  Lexer DeclLexer(SM.getLocForStartOfFile(FID), Context.getLangOpts(),
                  Buffer->getBufferStart(), SM.getCharacterData(LocStart),
                  Buffer->getBufferEnd());
  Token DeclToken;
  bool result = false;
  int parenthesisLevel = 0;

  while (!DeclLexer.LexFromRawLexer(DeclToken)) {
    if (DeclToken.getKind() == tok::TokenKind::l_paren)
      parenthesisLevel++;
    if (DeclToken.getKind() == tok::TokenKind::r_paren)
      parenthesisLevel--;
    if (DeclToken.getKind() == tok::TokenKind::semi)
      break;
    // if there is comma and we are not between open parenthesis then it is
    // two or more declatarions in this chain
    if (parenthesisLevel == 0 && DeclToken.getKind() == tok::TokenKind::comma)
      return false;

    if (DeclToken.isOneOf(tok::TokenKind::identifier,
                          tok::TokenKind::raw_identifier)) {
      auto TokenStr = DeclToken.getRawIdentifier().str();

      if (TokenStr == "typedef") {
        ResultRange =
            SourceRange(DeclToken.getLocation(), DeclToken.getEndLoc());
        result = true;
      }
    }
  }
  // assert if there was keyword 'typedef' in declaration
  assert(result && "No typedef found");

  return result;
}

Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const {
  assert(!TR->isReferenceType() && "Expressions can't have reference type.");

  Cl::Kinds kind = ClassifyInternal(Ctx, this);
  // C99 6.3.2.1: An lvalue is an expression with an object type or an
  //   incomplete type other than void.
  if (!Ctx.getLangOpts().CPlusPlus) {
    // Thus, no functions.
    if (TR->isFunctionType() || TR == Ctx.OverloadTy)
      kind = Cl::CL_Function;
    // No void either, but qualified void is OK because it is "other than void".
    // Void "lvalues" are classified as addressable void values, which are void
    // expressions whose address can be taken.
    else if (TR->isVoidType() && !TR.hasQualifiers())
      kind = (kind == Cl::CL_LValue ? Cl::CL_AddressableVoid : Cl::CL_Void);
  }

  // Enable this assertion for testing.
  switch (kind) {
  case Cl::CL_LValue: assert(getValueKind() == VK_LValue); break;
  case Cl::CL_XValue: assert(getValueKind() == VK_XValue); break;
  case Cl::CL_Function:
  case Cl::CL_Void:
  case Cl::CL_AddressableVoid:
  case Cl::CL_DuplicateVectorComponents:
  case Cl::CL_MemberFunction:
  case Cl::CL_SubObjCPropertySetting:
  case Cl::CL_ClassTemporary:
  case Cl::CL_ArrayTemporary:
  case Cl::CL_ObjCMessageRValue:
  case Cl::CL_PRValue: assert(getValueKind() == VK_RValue); break;
  }

  Cl::ModifiableType modifiable = Cl::CM_Untested;
  if (Loc)
    modifiable = IsModifiable(Ctx, this, kind, *Loc);
  return Classification(kind, modifiable);
}

/// ClassifyDecl - Return the classification of an expression referencing the
/// given declaration.
static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D) {
  // C++ [expr.prim.general]p6: The result is an lvalue if the entity is a
  //   function, variable, or data member and a prvalue otherwise.
  // In C, functions are not lvalues.
  // In addition, NonTypeTemplateParmDecl derives from VarDecl but isn't an
  // lvalue unless it's a reference type (C++ [temp.param]p6), so we need to
  // special-case this.

  if (isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance())
    return Cl::CL_MemberFunction;

  bool islvalue;
  if (const NonTypeTemplateParmDecl *NTTParm =
        dyn_cast<NonTypeTemplateParmDecl>(D))
    islvalue = NTTParm->getType()->isReferenceType();
  else
    islvalue = isa<VarDecl>(D) || isa<FieldDecl>(D) ||
	  isa<IndirectFieldDecl>(D) ||
      (Ctx.getLangOpts().CPlusPlus &&
        (isa<FunctionDecl>(D) || isa<FunctionTemplateDecl>(D)));

  return islvalue ? Cl::CL_LValue : Cl::CL_PRValue;
}

void ObjCMigrateASTConsumer::HandleTranslationUnit(ASTContext &Ctx) {
  
  TranslationUnitDecl *TU = Ctx.getTranslationUnitDecl();
  for (DeclContext::decl_iterator D = TU->decls_begin(), DEnd = TU->decls_end();
       D != DEnd; ++D) {
    if (ObjCInterfaceDecl *CDecl = dyn_cast<ObjCInterfaceDecl>(*D))
      migrateObjCInterfaceDecl(Ctx, CDecl);
  }
  
  Rewriter rewriter(Ctx.getSourceManager(), Ctx.getLangOpts());
  RewritesReceiver Rec(rewriter);
  Editor->applyRewrites(Rec);

  for (Rewriter::buffer_iterator
        I = rewriter.buffer_begin(), E = rewriter.buffer_end(); I != E; ++I) {
    FileID FID = I->first;
    RewriteBuffer &buf = I->second;
    const FileEntry *file = Ctx.getSourceManager().getFileEntryForID(FID);
    assert(file);
    SmallString<512> newText;
    llvm::raw_svector_ostream vecOS(newText);
    buf.write(vecOS);
    vecOS.flush();
    llvm::MemoryBuffer *memBuf = llvm::MemoryBuffer::getMemBufferCopy(
                   StringRef(newText.data(), newText.size()), file->getName());
    SmallString<64> filePath(file->getName());
    FileMgr.FixupRelativePath(filePath);
    Remapper.remap(filePath.str(), memBuf);
  }

  if (IsOutputFile) {
    Remapper.flushToFile(MigrateDir, Ctx.getDiagnostics());
  } else {
    Remapper.flushToDisk(MigrateDir, Ctx.getDiagnostics());
  }
}

/// AnalyzeAsmString - Analyze the asm string of the current asm, decomposing
/// it into pieces.  If the asm string is erroneous, emit errors and return
/// true, otherwise return false.
unsigned GCCAsmStmt::AnalyzeAsmString(SmallVectorImpl<AsmStringPiece>&Pieces,
                                const ASTContext &C, unsigned &DiagOffs) const {
  StringRef Str = getAsmString()->getString();
  const char *StrStart = Str.begin();
  const char *StrEnd = Str.end();
  const char *CurPtr = StrStart;

  // "Simple" inline asms have no constraints or operands, just convert the asm
  // string to escape $'s.
  if (isSimple()) {
    std::string Result;
    for (; CurPtr != StrEnd; ++CurPtr) {
      switch (*CurPtr) {
      case '$':
        Result += "$$";
        break;
      default:
        Result += *CurPtr;
        break;
      }
    }
    Pieces.push_back(AsmStringPiece(Result));
    return 0;
  }

  // CurStringPiece - The current string that we are building up as we scan the
  // asm string.
  std::string CurStringPiece;

  bool HasVariants = !C.getTargetInfo().hasNoAsmVariants();

  while (1) {
    // Done with the string?
    if (CurPtr == StrEnd) {
      if (!CurStringPiece.empty())
        Pieces.push_back(AsmStringPiece(CurStringPiece));
      return 0;
    }

    char CurChar = *CurPtr++;
    switch (CurChar) {
    case '$': CurStringPiece += "$$"; continue;
    case '{': CurStringPiece += (HasVariants ? "$(" : "{"); continue;
    case '|': CurStringPiece += (HasVariants ? "$|" : "|"); continue;
    case '}': CurStringPiece += (HasVariants ? "$)" : "}"); continue;
    case '%':
      break;
    default:
      CurStringPiece += CurChar;
      continue;
    }

    // Escaped "%" character in asm string.
    if (CurPtr == StrEnd) {
      // % at end of string is invalid (no escape).
      DiagOffs = CurPtr-StrStart-1;
      return diag::err_asm_invalid_escape;
    }

    char EscapedChar = *CurPtr++;
    if (EscapedChar == '%') {  // %% -> %
      // Escaped percentage sign.
      CurStringPiece += '%';
      continue;
    }

    if (EscapedChar == '=') {  // %= -> Generate an unique ID.
      CurStringPiece += "${:uid}";
      continue;
    }

    // Otherwise, we have an operand.  If we have accumulated a string so far,
    // add it to the Pieces list.
    if (!CurStringPiece.empty()) {
      Pieces.push_back(AsmStringPiece(CurStringPiece));
      CurStringPiece.clear();
    }

    // Handle operands that have asmSymbolicName (e.g., %x[foo]) and those that
    // don't (e.g., %x4). 'x' following the '%' is the constraint modifier.

    const char *Begin = CurPtr - 1; // Points to the character following '%'.
    const char *Percent = Begin - 1; // Points to '%'.

    if (isLetter(EscapedChar)) {
      if (CurPtr == StrEnd) { // Premature end.
        DiagOffs = CurPtr-StrStart-1;
        return diag::err_asm_invalid_escape;
      }
      EscapedChar = *CurPtr++;
    }

    const TargetInfo &TI = C.getTargetInfo();
    const SourceManager &SM = C.getSourceManager();
    const LangOptions &LO = C.getLangOpts();

    // Handle operands that don't have asmSymbolicName (e.g., %x4).
//.........这里部分代码省略.........

 explicit InserterVisitor(CompilerInstance *CI)
   : astContext(&(CI->getASTContext()))
 {
     rewriter.setSourceMgr(astContext->getSourceManager(), astContext->getLangOpts());
 }

/// GetDiagForGotoScopeDecl - If this decl induces a new goto scope, return a
/// diagnostic that should be emitted if control goes over it. If not, return 0.
static ScopePair GetDiagForGotoScopeDecl(ASTContext &Context, const Decl *D) {
  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
    unsigned InDiag = 0;
    if (VD->getType()->isVariablyModifiedType())
      InDiag = diag::note_protected_by_vla;

    if (VD->hasAttr<BlocksAttr>())
      return ScopePair(diag::note_protected_by___block,
                       diag::note_exits___block);

    if (VD->hasAttr<CleanupAttr>())
      return ScopePair(diag::note_protected_by_cleanup,
                       diag::note_exits_cleanup);

    if (Context.getLangOpts().ObjCAutoRefCount && VD->hasLocalStorage()) {
      switch (VD->getType().getObjCLifetime()) {
      case Qualifiers::OCL_None:
      case Qualifiers::OCL_ExplicitNone:
      case Qualifiers::OCL_Autoreleasing:
        break;

      case Qualifiers::OCL_Strong:
      case Qualifiers::OCL_Weak:
        return ScopePair(diag::note_protected_by_objc_ownership,
                         diag::note_exits_objc_ownership);
      }
    }

    if (Context.getLangOpts().CPlusPlus && VD->hasLocalStorage()) {
      // C++11 [stmt.dcl]p3:
      //   A program that jumps from a point where a variable with automatic
      //   storage duration is not in scope to a point where it is in scope
      //   is ill-formed unless the variable has scalar type, class type with
      //   a trivial default constructor and a trivial destructor, a 
      //   cv-qualified version of one of these types, or an array of one of
      //   the preceding types and is declared without an initializer.

      // C++03 [stmt.dcl.p3:
      //   A program that jumps from a point where a local variable
      //   with automatic storage duration is not in scope to a point
      //   where it is in scope is ill-formed unless the variable has
      //   POD type and is declared without an initializer.

      const Expr *Init = VD->getInit();
      if (!Init)
        return ScopePair(InDiag, 0);

      const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(Init);
      if (EWC)
        Init = EWC->getSubExpr();

      const MaterializeTemporaryExpr *M = NULL;
      Init = Init->findMaterializedTemporary(M);

      SmallVector<SubobjectAdjustment, 2> Adjustments;
      Init = Init->skipRValueSubobjectAdjustments(Adjustments);

      QualType QT = Init->getType();
      if (QT.isNull())
        return ScopePair(diag::note_protected_by_variable_init, 0);

      const Type *T = QT.getTypePtr();
      if (T->isArrayType())
        T = T->getBaseElementTypeUnsafe();

      const CXXRecordDecl *Record = T->getAsCXXRecordDecl();
      if (!Record)
        return ScopePair(diag::note_protected_by_variable_init, 0);

      // If we need to call a non trivial destructor for this variable,
      // record an out diagnostic.
      unsigned OutDiag = 0;
      if (!Init->isGLValue() && !Record->hasTrivialDestructor())
        OutDiag = diag::note_exits_dtor;

      if (const CXXConstructExpr *cce = dyn_cast<CXXConstructExpr>(Init)) {
        const CXXConstructorDecl *ctor = cce->getConstructor();
        if (ctor->isTrivial() && ctor->isDefaultConstructor()) {
          if (OutDiag)
            InDiag = diag::note_protected_by_variable_nontriv_destructor;
          else if (!Record->isPOD())
            InDiag = diag::note_protected_by_variable_non_pod;
          return ScopePair(InDiag, OutDiag);
        }
      }

      return ScopePair(diag::note_protected_by_variable_init, OutDiag);
    }

    return ScopePair(InDiag, 0);
  }

  if (const TypedefDecl *TD = dyn_cast<TypedefDecl>(D)) {
    if (TD->getUnderlyingType()->isVariablyModifiedType())
      return ScopePair(diag::note_protected_by_vla_typedef, 0);
  }

  if (const TypeAliasDecl *TD = dyn_cast<TypeAliasDecl>(D)) {
//.........这里部分代码省略.........

static bool checkReturnValueType(const ASTContext &Ctx, const Expr *E,
                                 QualType &DeducedType,
                                 QualType &AlternateType) {
  // Handle ReturnStmts with no expressions.
  if (!E) {
    if (AlternateType.isNull())
      AlternateType = Ctx.VoidTy;

    return Ctx.hasSameType(DeducedType, Ctx.VoidTy);
  }

  QualType StrictType = E->getType();
  QualType LooseType = StrictType;

  // In C, enum constants have the type of their underlying integer type,
  // not the enum. When inferring block return types, we should allow
  // the enum type if an enum constant is used, unless the enum is
  // anonymous (in which case there can be no variables of its type).
  if (!Ctx.getLangOpts().CPlusPlus) {
    const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts());
    if (DRE) {
      const Decl *D = DRE->getDecl();
      if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) {
        const EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
        if (Enum->getDeclName() || Enum->getTypedefNameForAnonDecl())
          LooseType = Ctx.getTypeDeclType(Enum);
      }
    }
  }

  // Special case for the first return statement we find.
  // The return type has already been tentatively set, but we might still
  // have an alternate type we should prefer.
  if (AlternateType.isNull())
    AlternateType = LooseType;

  if (Ctx.hasSameType(DeducedType, StrictType)) {
    // FIXME: The loose type is different when there are constants from two
    // different enums. We could consider warning here.
    if (AlternateType != Ctx.DependentTy)
      if (!Ctx.hasSameType(AlternateType, LooseType))
        AlternateType = Ctx.VoidTy;
    return true;
  }

  if (Ctx.hasSameType(DeducedType, LooseType)) {
    // Use DependentTy to signal that we're using an alternate type and may
    // need to add casts somewhere.
    AlternateType = Ctx.DependentTy;
    return true;
  }

  if (Ctx.hasSameType(AlternateType, StrictType) ||
      Ctx.hasSameType(AlternateType, LooseType)) {
    DeducedType = AlternateType;
    // Use DependentTy to signal that we're using an alternate type and may
    // need to add casts somewhere.
    AlternateType = Ctx.DependentTy;
    return true;
  }

  return false;
}

void HTMLPrinter::Initialize(ASTContext &context) {
  R.setSourceMgr(context.getSourceManager(), context.getLangOpts());
}

 explicit ExampleVisitor(CompilerInstance *CI) 
   : astContext(&(CI->getASTContext())) // initialize private members
 {
     rewriter.setSourceMgr(astContext->getSourceManager(), astContext->getLangOpts());
 }

static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
  // This function takes the first stab at classifying expressions.
  const LangOptions &Lang = Ctx.getLangOpts();

  switch (E->getStmtClass()) {
  case Stmt::NoStmtClass:
#define ABSTRACT_STMT(Kind)
#define STMT(Kind, Base) case Expr::Kind##Class:
#define EXPR(Kind, Base)
#include "clang/AST/StmtNodes.inc"
    llvm_unreachable("cannot classify a statement");

    // First come the expressions that are always lvalues, unconditionally.
  case Expr::ObjCIsaExprClass:
    // C++ [expr.prim.general]p1: A string literal is an lvalue.
  case Expr::StringLiteralClass:
    // @encode is equivalent to its string
  case Expr::ObjCEncodeExprClass:
    // __func__ and friends are too.
  case Expr::PredefinedExprClass:
    // Property references are lvalues
  case Expr::ObjCSubscriptRefExprClass:
  case Expr::ObjCPropertyRefExprClass:
    // C++ [expr.typeid]p1: The result of a typeid expression is an lvalue of...
  case Expr::CXXTypeidExprClass:
    // Unresolved lookups and uncorrected typos get classified as lvalues.
    // FIXME: Is this wise? Should they get their own kind?
  case Expr::UnresolvedLookupExprClass:
  case Expr::UnresolvedMemberExprClass:
  case Expr::TypoExprClass:
  case Expr::DependentCoawaitExprClass:
  case Expr::CXXDependentScopeMemberExprClass:
  case Expr::DependentScopeDeclRefExprClass:
    // ObjC instance variables are lvalues
    // FIXME: ObjC++0x might have different rules
  case Expr::ObjCIvarRefExprClass:
  case Expr::FunctionParmPackExprClass:
  case Expr::MSPropertyRefExprClass:
  case Expr::MSPropertySubscriptExprClass:
  case Expr::OMPArraySectionExprClass:
    return Cl::CL_LValue;

    // C99 6.5.2.5p5 says that compound literals are lvalues.
    // In C++, they're prvalue temporaries, except for file-scope arrays.
  case Expr::CompoundLiteralExprClass:
    return !E->isLValue() ? ClassifyTemporary(E->getType()) : Cl::CL_LValue;

    // Expressions that are prvalues.
  case Expr::CXXBoolLiteralExprClass:
  case Expr::CXXPseudoDestructorExprClass:
  case Expr::UnaryExprOrTypeTraitExprClass:
  case Expr::CXXNewExprClass:
  case Expr::CXXThisExprClass:
  case Expr::CXXNullPtrLiteralExprClass:
  case Expr::ImaginaryLiteralClass:
  case Expr::GNUNullExprClass:
  case Expr::OffsetOfExprClass:
  case Expr::CXXThrowExprClass:
  case Expr::ShuffleVectorExprClass:
  case Expr::ConvertVectorExprClass:
  case Expr::IntegerLiteralClass:
  case Expr::CharacterLiteralClass:
  case Expr::AddrLabelExprClass:
  case Expr::CXXDeleteExprClass:
  case Expr::ImplicitValueInitExprClass:
  case Expr::BlockExprClass:
  case Expr::FloatingLiteralClass:
  case Expr::CXXNoexceptExprClass:
  case Expr::CXXScalarValueInitExprClass:
  case Expr::TypeTraitExprClass:
  case Expr::ArrayTypeTraitExprClass:
  case Expr::ExpressionTraitExprClass:
  case Expr::ObjCSelectorExprClass:
  case Expr::ObjCProtocolExprClass:
  case Expr::ObjCStringLiteralClass:
  case Expr::ObjCBoxedExprClass:
  case Expr::ObjCArrayLiteralClass:
  case Expr::ObjCDictionaryLiteralClass:
  case Expr::ObjCBoolLiteralExprClass:
  case Expr::ObjCAvailabilityCheckExprClass:
  case Expr::ParenListExprClass:
  case Expr::SizeOfPackExprClass:
  case Expr::SubstNonTypeTemplateParmPackExprClass:
  case Expr::AsTypeExprClass:
  case Expr::ObjCIndirectCopyRestoreExprClass:
  case Expr::AtomicExprClass:
  case Expr::CXXFoldExprClass:
  case Expr::ArrayInitLoopExprClass:
  case Expr::ArrayInitIndexExprClass:
  case Expr::NoInitExprClass:
  case Expr::DesignatedInitUpdateExprClass:
  case Expr::CoyieldExprClass:
    return Cl::CL_PRValue;

    // Next come the complicated cases.
  case Expr::SubstNonTypeTemplateParmExprClass:
    return ClassifyInternal(Ctx,
                 cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement());

    // C, C++98 [expr.sub]p1: The result is an lvalue of type "T".
//.........这里部分代码省略.........