C#

CSHARP.CLASS.CAST : Risky Class Cast (C#)

要旨

A classcast might be incorrect at runtime.

(Note that entry methods are determined with respect to the setting of CSHARP_ANALYSIS_ENTRY_POINTS_MODE.)

C# checks explicit type downcasts at runtime. If they do not hold, a runtime exception is thrown. This checker verifies that casts will be satisfied at runtime, so that they will never throw an exception.

プロパティ

クラス名 Risky Class Cast (C#)
日本語クラス名 Risky Class Cast (C#)
クラス分類 信頼性 (reliability)
ニーモニック CSHARP.CLASS.CAST
カテゴリー
CWE CWE:704 Incorrect Type Conversion or Cast
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="Risky Class Cast (C#)"

例 

using System;

namespace DocumentationExamples
{

    public class Classcast
    {

        private object f;
        private object g = "hi";
        public void M1(object o)
        {
            if (((string)o).StartsWith("hello"))       // "Risky Class Cast (C#)" warning always issued here
                                                       // - M1() called with ClassCast argument in the body of Caller1()
                Console.WriteLine("nice to meet you");
        }
        public void M2(string s, object o)
        {
            if (((string)o).StartsWith("hello"))       // "Risky Class Cast (C#)" warning always issued here
                                                       // - no evidence of M2() being called with a risky value for o in this code, but
                                                       //   M2() is public so could be called with an incompatible argument from elsewhere
               Console.WriteLine("nice to meet you");
        }
        public void M3(string s, object o)
        {
            if (((string)Wrap(o)).StartsWith("hello")) // "Risky Class Cast (C#)" warning issued here
                                                       // if CSHARP_ANALYSIS_PEDANTIC_MODE=Yes
                Console.WriteLine("nice to meet you");
        }
        public void M4()
        {
            if (((string)f).StartsWith("hello"))       // "Risky Class Cast (C#)" warning issued here
                                                       // if CSHARP_ANALYSIS_PEDANTIC_MODE=Yes
                Console.WriteLine("nice to meet you");
        }
        public void M5()
        {
            if (((string)g).StartsWith("hello"))                          // ok: safe cast
                Console.WriteLine("nice to meet you");
        }
        private object Wrap(object o)
        {
            return o;
        }
        public void Caller1()
        {
            M1("hi");
            M1(this);
        }
        public void Caller2()
        {
            M2("ciao", "hello");
            M2("come stai", "how are you?");
        }
        public void Caller3()
        {
            M3("ciao", "hello");
            M3("come stai", f = new object());
        }
    }
}

解決法

For each classcast warning, verify that all types that will ever reach that program point are assignable to the type used for the cast.

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。