C++ ASTContext::getLangOptions方法代码示例

/// \brief \arg Loc is the end of a statement range. This returns the location
/// of the semicolon following the statement.
/// If no semicolon is found or the location is inside a macro, the returned
/// source location will be invalid.
SourceLocation trans::findSemiAfterLocation(SourceLocation loc,
                                            ASTContext &Ctx) {
  SourceManager &SM = Ctx.getSourceManager();
  if (loc.isMacroID()) {
    if (!Lexer::isAtEndOfMacroExpansion(loc, SM, Ctx.getLangOptions()))
      return SourceLocation();
    loc = SM.getExpansionRange(loc).second;
  }
  loc = Lexer::getLocForEndOfToken(loc, /*Offset=*/0, SM, Ctx.getLangOptions());

  // Break down the source location.
  std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(loc);

  // Try to load the file buffer.
  bool invalidTemp = false;
  StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
  if (invalidTemp)
    return SourceLocation();

  const char *tokenBegin = file.data() + locInfo.second;

  // Lex from the start of the given location.
  Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
              Ctx.getLangOptions(),
              file.begin(), tokenBegin, file.end());
  Token tok;
  lexer.LexFromRawLexer(tok);
  if (tok.isNot(tok::semi))
    return SourceLocation();

  return tok.getLocation();
}

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.getLangOptions().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".
    else if (TR->isVoidType() && !Ctx.getCanonicalType(TR).hasQualifiers())
      kind = 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_DuplicateVectorComponents:
  case Cl::CL_MemberFunction:
  case Cl::CL_SubObjCPropertySetting:
  case Cl::CL_ClassTemporary:
  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);
}

bool trans::canApplyWeak(ASTContext &Ctx, QualType type,
                         bool AllowOnUnknownClass) {
  if (!Ctx.getLangOptions().ObjCRuntimeHasWeak)
    return false;

  QualType T = type;
  if (T.isNull())
    return false;

  while (const PointerType *ptr = T->getAs<PointerType>())
    T = ptr->getPointeeType();
  if (const ObjCObjectPointerType *ObjT = T->getAs<ObjCObjectPointerType>()) {
    ObjCInterfaceDecl *Class = ObjT->getInterfaceDecl();
    if (!AllowOnUnknownClass && (!Class || Class->getName() == "NSObject"))
      return false; // id/NSObject is not safe for weak.
    if (!AllowOnUnknownClass && Class->isForwardDecl())
      return false; // forward classes are not verifiable, therefore not safe.
    if (Class->isArcWeakrefUnavailable())
      return false;
    if (isClassInWeakBlacklist(Class))
      return false;
  }

  return true;
}

/// \brief Returns a value indicating whether this function
/// corresponds to a builtin function.
///
/// The function corresponds to a built-in function if it is
/// declared at translation scope or within an extern "C" block and
/// its name matches with the name of a builtin. The returned value
/// will be 0 for functions that do not correspond to a builtin, a
/// value of type \c Builtin::ID if in the target-independent range 
/// \c [1,Builtin::First), or a target-specific builtin value.
unsigned FunctionDecl::getBuiltinID(ASTContext &Context) const {
  if (!getIdentifier() || !getIdentifier()->getBuiltinID())
    return 0;

  unsigned BuiltinID = getIdentifier()->getBuiltinID();
  if (!Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
    return BuiltinID;

  // This function has the name of a known C library
  // function. Determine whether it actually refers to the C library
  // function or whether it just has the same name.

  // If this is a static function, it's not a builtin.
  if (getStorageClass() == Static)
    return 0;

  // If this function is at translation-unit scope and we're not in
  // C++, it refers to the C library function.
  if (!Context.getLangOptions().CPlusPlus &&
      getDeclContext()->isTranslationUnit())
    return BuiltinID;

  // If the function is in an extern "C" linkage specification and is
  // not marked "overloadable", it's the real function.
  if (isa<LinkageSpecDecl>(getDeclContext()) &&
      cast<LinkageSpecDecl>(getDeclContext())->getLanguage() 
        == LinkageSpecDecl::lang_c &&
      !getAttr<OverloadableAttr>())
    return BuiltinID;

  // Not a builtin
  return 0;
}

static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E) {
  assert(Ctx.getLangOptions().CPlusPlus &&
         "This is only relevant for C++.");
  // C++ [expr.ass]p1: All [...] return an lvalue referring to the left operand.
  // Except we override this for writes to ObjC properties.
  if (E->isAssignmentOp())
    return (E->getLHS()->getObjectKind() == OK_ObjCProperty
              ? Cl::CL_PRValue : Cl::CL_LValue);

  // C++ [expr.comma]p1: the result is of the same value category as its right
  //   operand, [...].
  if (E->getOpcode() == BO_Comma)
    return ClassifyInternal(Ctx, E->getRHS());

  // C++ [expr.mptr.oper]p6: The result of a .* expression whose second operand
  //   is a pointer to a data member is of the same value category as its first
  //   operand.
  if (E->getOpcode() == BO_PtrMemD)
    return E->getType()->isFunctionType() ? Cl::CL_MemberFunction :
      ClassifyInternal(Ctx, E->getLHS());

  // C++ [expr.mptr.oper]p6: The result of an ->* expression is an lvalue if its
  //   second operand is a pointer to data member and a prvalue otherwise.
  if (E->getOpcode() == BO_PtrMemI)
    return E->getType()->isFunctionType() ?
      Cl::CL_MemberFunction : Cl::CL_LValue;

  // All other binary operations are prvalues.
  return Cl::CL_PRValue;
}

/// isRequiredDecl - Check if this is a "required" Decl, which must be seen by
/// consumers of the AST.
///
/// Such decls will always be deserialized from the PCH file, so we would like
/// this to be as restrictive as possible. Currently the predicate is driven by
/// code generation requirements, if other clients have a different notion of
/// what is "required" then we may have to consider an alternate scheme where
/// clients can iterate over the top-level decls and get information on them,
/// without necessary deserializing them. We could explicitly require such
/// clients to use a separate API call to "realize" the decl. This should be
/// relatively painless since they would presumably only do it for top-level
/// decls.
//
// FIXME: This predicate is essentially IRgen's predicate to determine whether a
// declaration can be deferred. Merge them somehow.
static bool isRequiredDecl(const Decl *D, ASTContext &Context) {
  // File scoped assembly must be seen.
  if (isa<FileScopeAsmDecl>(D))
    return true;

  // Otherwise if this isn't a function or a file scoped variable it doesn't
  // need to be seen.
  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
    if (!VD->isFileVarDecl())
      return false;
  } else if (!isa<FunctionDecl>(D))
    return false;

  // Aliases and used decls must be seen.
  if (D->hasAttr<AliasAttr>() || D->hasAttr<UsedAttr>())
    return true;

  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
    // Forward declarations don't need to be seen.
    if (!FD->isThisDeclarationADefinition())
      return false;

    // Constructors and destructors must be seen.
    if (FD->hasAttr<ConstructorAttr>() || FD->hasAttr<DestructorAttr>())
      return true;

    // Otherwise, this is required unless it is static.
    //
    // FIXME: Inlines.
    return FD->getStorageClass() != FunctionDecl::Static;
  } else {
    const VarDecl *VD = cast<VarDecl>(D);

    // In C++, this doesn't need to be seen if it is marked "extern".
    if (Context.getLangOptions().CPlusPlus && !VD->getInit() &&
        (VD->getStorageClass() == VarDecl::Extern ||
         VD->isExternC()))
      return false;

    // In C, this doesn't need to be seen unless it is a definition.
    if (!Context.getLangOptions().CPlusPlus && !VD->getInit())
      return false;

    // Otherwise, this is required unless it is static.
    return VD->getStorageClass() != VarDecl::Static;
  }
}

bool VarDecl::isTentativeDefinition(ASTContext &Context) const {
  if (!isFileVarDecl() || Context.getLangOptions().CPlusPlus)
    return false;

  const VarDecl *Def = 0;
  return (!getDefinition(Def) &&
          (getStorageClass() == None || getStorageClass() == Static));
}

static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E) {
  if (E->getType() == Ctx.UnknownAnyTy)
    return (isa<FunctionDecl>(E->getMemberDecl())
              ? Cl::CL_PRValue : Cl::CL_LValue);

  // Handle C first, it's easier.
  if (!Ctx.getLangOptions().CPlusPlus) {
    // C99 6.5.2.3p3
    // For dot access, the expression is an lvalue if the first part is. For
    // arrow access, it always is an lvalue.
    if (E->isArrow())
      return Cl::CL_LValue;
    // ObjC property accesses are not lvalues, but get special treatment.
    Expr *Base = E->getBase()->IgnoreParens();
    if (isa<ObjCPropertyRefExpr>(Base))
      return Cl::CL_SubObjCPropertySetting;
    return ClassifyInternal(Ctx, Base);
  }

  NamedDecl *Member = E->getMemberDecl();
  // C++ [expr.ref]p3: E1->E2 is converted to the equivalent form (*(E1)).E2.
  // C++ [expr.ref]p4: If E2 is declared to have type "reference to T", then
  //   E1.E2 is an lvalue.
  if (ValueDecl *Value = dyn_cast<ValueDecl>(Member))
    if (Value->getType()->isReferenceType())
      return Cl::CL_LValue;

  //   Otherwise, one of the following rules applies.
  //   -- If E2 is a static member [...] then E1.E2 is an lvalue.
  if (isa<VarDecl>(Member) && Member->getDeclContext()->isRecord())
    return Cl::CL_LValue;

  //   -- If E2 is a non-static data member [...]. If E1 is an lvalue, then
  //      E1.E2 is an lvalue; if E1 is an xvalue, then E1.E2 is an xvalue;
  //      otherwise, it is a prvalue.
  if (isa<FieldDecl>(Member)) {
    // *E1 is an lvalue
    if (E->isArrow())
      return Cl::CL_LValue;
    Expr *Base = E->getBase()->IgnoreParenImpCasts();
    if (isa<ObjCPropertyRefExpr>(Base))
      return Cl::CL_SubObjCPropertySetting;
    return ClassifyInternal(Ctx, E->getBase());
  }

  //   -- If E2 is a [...] member function, [...]
  //      -- If it refers to a static member function [...], then E1.E2 is an
  //         lvalue; [...]
  //      -- Otherwise [...] E1.E2 is a prvalue.
  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Member))
    return Method->isStatic() ? Cl::CL_LValue : Cl::CL_MemberFunction;

  //   -- If E2 is a member enumerator [...], the expression E1.E2 is a prvalue.
  // So is everything else we haven't handled yet.
  return Cl::CL_PRValue;
}

/// ClassifyUnnamed - Return the classification of an expression yielding an
/// unnamed value of the given type. This applies in particular to function
/// calls and casts.
static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T) {
  // In C, function calls are always rvalues.
  if (!Ctx.getLangOptions().CPlusPlus) return Cl::CL_PRValue;

  // C++ [expr.call]p10: A function call is an lvalue if the result type is an
  //   lvalue reference type or an rvalue reference to function type, an xvalue
  //   if the result type is an rvalue refernence to object type, and a prvalue
  //   otherwise.
  if (T->isLValueReferenceType())
    return Cl::CL_LValue;
  const RValueReferenceType *RV = T->getAs<RValueReferenceType>();
  if (!RV) // Could still be a class temporary, though.
    return T->isRecordType() ? Cl::CL_ClassTemporary : Cl::CL_PRValue;

  return RV->getPointeeType()->isFunctionType() ? Cl::CL_LValue : Cl::CL_XValue;
}

bool FunctionDecl::isExternC(ASTContext &Context) const {
  // In C, any non-static, non-overloadable function has external
  // linkage.
  if (!Context.getLangOptions().CPlusPlus)
    return getStorageClass() != Static && !getAttr<OverloadableAttr>();

  for (const DeclContext *DC = getDeclContext(); !DC->isTranslationUnit(); 
       DC = DC->getParent()) {
    if (const LinkageSpecDecl *Linkage = dyn_cast<LinkageSpecDecl>(DC))  {
      if (Linkage->getLanguage() == LinkageSpecDecl::lang_c)
        return getStorageClass() != Static && 
               !getAttr<OverloadableAttr>();

      break;
    }
  }

  return false;
}

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

  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 << "]";
}

static Cl::Kinds ClassifyConditional(ASTContext &Ctx, const Expr *True,
                                     const Expr *False) {
  assert(Ctx.getLangOptions().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;
}

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.getLangOptions().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".
    else if (TR->isVoidType() && !Ctx.getCanonicalType(TR).hasQualifiers())
      kind = Cl::CL_Void;
  }

  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) ||
      (Ctx.getLangOptions().CPlusPlus &&
        (isa<FunctionDecl>(D) || isa<FunctionTemplateDecl>(D)));

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

static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E,
                                       Cl::Kinds Kind, SourceLocation &Loc) {
  // As a general rule, we only care about lvalues. But there are some rvalues
  // for which we want to generate special results.
  if (Kind == Cl::CL_PRValue) {
    // For the sake of better diagnostics, we want to specifically recognize
    // use of the GCC cast-as-lvalue extension.
    if (const ExplicitCastExpr *CE =
          dyn_cast<ExplicitCastExpr>(E->IgnoreParens())) {
      if (CE->getSubExpr()->IgnoreParenImpCasts()->isLValue()) {
        Loc = CE->getExprLoc();
        return Cl::CM_LValueCast;
      }
    }
  }
  if (Kind != Cl::CL_LValue)
    return Cl::CM_RValue;

  // This is the lvalue case.
  // Functions are lvalues in C++, but not modifiable. (C++ [basic.lval]p6)
  if (Ctx.getLangOptions().CPlusPlus && E->getType()->isFunctionType())
    return Cl::CM_Function;

  // You cannot assign to a variable outside a block from within the block if
  // it is not marked __block, e.g.
  //   void takeclosure(void (^C)(void));
  //   void func() { int x = 1; takeclosure(^{ x = 7; }); }
  if (const BlockDeclRefExpr *BDR = dyn_cast<BlockDeclRefExpr>(E)) {
    if (!BDR->isByRef() && isa<VarDecl>(BDR->getDecl()))
      return Cl::CM_NotBlockQualified;
  }

  // Assignment to a property in ObjC is an implicit setter access. But a
  // setter might not exist.
  if (const ObjCPropertyRefExpr *Expr = dyn_cast<ObjCPropertyRefExpr>(E)) {
    if (Expr->isImplicitProperty() && Expr->getImplicitPropertySetter() == 0)
      return Cl::CM_NoSetterProperty;
  }

  CanQualType CT = Ctx.getCanonicalType(E->getType());
  // Const stuff is obviously not modifiable.
  if (CT.isConstQualified())
    return Cl::CM_ConstQualified;
  // Arrays are not modifiable, only their elements are.
  if (CT->isArrayType())
    return Cl::CM_ArrayType;
  // Incomplete types are not modifiable.
  if (CT->isIncompleteType())
    return Cl::CM_IncompleteType;

  // Records with any const fields (recursively) are not modifiable.
  if (const RecordType *R = CT->getAs<RecordType>()) {
    assert((E->getObjectKind() == OK_ObjCProperty ||
            !Ctx.getLangOptions().CPlusPlus) &&
           "C++ struct assignment should be resolved by the "
           "copy assignment operator.");
    if (R->hasConstFields())
      return Cl::CM_ConstQualified;
  }

  return Cl::CM_Modifiable;
}