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Useless upcast — CodeQL query help documentation

ID: cs/useless-upcast
Kind: problem
Security severity: 
Severity: warning
Precision: medium
Tags:
   - quality
   - maintainability
   - useless-code
   - external/cwe/cwe-561
Query suites:
   - csharp-security-and-quality.qls

Click to see the query in the CodeQL repository

In most situations, casting an expression where there exists a corresponding implicit conversion serves no purpose.

Recommendation

Remove the redundant cast.

Example

In this example, casting explicitly from Sub to Super is redundant.

class Bad
{
    class Super {}
    class Sub : Super {}

    void M()
    {
        var sub = new Sub();
        Super super = (Super)sub;
    }
}

The code above can be fixed, either by removing the explicit cast, or by making super an implicitly typed (var) variable.

References