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CodeSonar® 9.2p0 CONFIDENTIAL CodeSecure Inc
C and C++

LANG.CAST.OBJSLICE : Object Slicing

要旨

A value of class type C is assigned to a variable of type B, where B is a base class of C.

In such an assignment, any additional member data that is present in class C but not in class B is not copied into the variable. The resolutions of any subsequent method calls on the variable may also be confusing for human readers.

Use configuration file parameter OBJSLICE_WARN_NEW_MEMBER_ONLY=Yes to specifies whether or not warnings should be restricted to the case where class C contains data members that are not present in class B (and so will be "sliced off" in the assignment).

プロパティ

クラス名 Object Slicing
日本語クラス名 Object Slicing
クラス分類 スタイル (style)
ニーモニック LANG.CAST.OBJSLICE
カテゴリー
AUTOSARC++14 AUTOSARC++14:A12-8-6 Copy and move constructors and copy assignment and move assignment operators shall be declared protected or defined "=delete" in base class.
  AUTOSARC++14:A15-3-5 A class type exception shall be caught by reference or const reference.
MisraC++2008 MisraC++2008:12-8-2 The copy assignment operator shall be declared protected or private in an abstract class.
  MisraC++2008:15-3-5 A class type exception shall always be caught by reference.
MisraC++2023 MisraC++2023:18.3.2 An exception of class type shall be caught by const reference or reference
CERT-CPP CERT-CPP:OOP51-CPP Do not slice derived objects
JSF++ JSF++:96 Arrays shall not be treated polymorphically.
  JSF++:183 Every possible measure should be taken to avoid type casting.
対応言語 C++ のみ利用可能です。 C は利用できません。
有効/無効設定 このワーニングクラスのチェックはデフォルトで有効になっています。チェックを無効にするにはプロジェクト設定ファイル （configuration file）に以下の WARNING_FILTER ルールを追加してください。 
WARNING_FILTER += discard class="Object Slicing"

例 

namespace lang_cast_objslice {
  static int g = 0;

  class Base {
  public:
    Base(){b=++g;}
    int b;
    void f(void){}
  };

  class Derived: public Base {
  public:
    Derived(){d=1;};
    int d;
    void g(void){}
  };

  class DerivedNoFields: public Base {};

  void useBase(Base inb){}

  void makeAssignments(void){
    Base baseobj;
    Derived derivedobj;
    DerivedNoFields derivednofieldsobj;

    useBase(baseobj);                        // ok: baseobj is a Base
    useBase(derivedobj);         // 'Object Slicing' warning issued here
    useBase(derivednofieldsobj); // 'Object Slicing' warning issued here only if OBJSLICE_WARN_NEW_MEMBER_ONLY=No

    baseobj=derivedobj;          // 'Object Slicing' warning issued here
    useBase(baseobj);                        // ok: baseobj is a Base

    baseobj=derivednofieldsobj;  // 'Object Slicing' warning issued here only if OBJSLICE_WARN_NEW_MEMBER_ONLY=No
    useBase(baseobj);                        // ok: baseobj is a Base
  }
}

関連のある設定ファイルパラメータ

設定ファイルの以下のパラメータがこのワーニングクラスのチェックに影響します。

 

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