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CodeSonar® 9.2p0 CONFIDENTIAL CodeSecure Inc
C#

CSHARP.CLASS.IOF.T : Instanceof Always True (C#)

要旨

Type-testing is always true.

This checker looks for is operators that are useless, in the sense that they are always true or always false and can hence be removed from the code. This can improve the efficiency of the program. Moreover, a useless is test is often the sign of a programming bug.

プロパティ

クラス名 Instanceof Always True (C#)
日本語クラス名 Instanceof Always True (C#)
クラス分類 信頼性 (reliability)
ニーモニック CSHARP.CLASS.IOF.T
カテゴリー
CWE CWE:571 Expression is Always True
対応言語 C# で利用可能です。
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="Instanceof Always True (C#)"

例 

using System;

namespace DocumentationExamples
{
    public class UselessInstanceof
    {
        public static void Main(string[] args)
        {
            UselessInstanceofA a = new UselessInstanceofB();
            switch (DateTime.Now.Millisecond % 3)
            {
                case 0:
                case 1:
                    a = new UselessInstanceofA(); break;
                case 2:
                    a = new UselessInstanceofC(); break;
            }
            if (a is UselessInstanceofC)
                Foo(a);
        }
        private static void Foo(UselessInstanceofA par)
        {
            if (par is UselessInstanceofB)  // "Instanceof Always True (C#)" warning issued here
                Console.WriteLine("par is a B");
        }
    }
    public class UselessInstanceofA { }
    public class UselessInstanceofB : UselessInstanceofA { }
    public class UselessInstanceofC : UselessInstanceofB { }
}

解決法

Check if the is operator can be actually removed and that it is not the sign of an actual programming bug.

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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