Useless type test¶
ID: cs/useless-type-test
Kind: problem
Security severity:
Severity: warning
Precision: medium
Tags:
- maintainability
- language-features
- external/cwe/cwe-561
Query suites:
- csharp-security-and-quality.qls
Click to see the query in the CodeQL repository
For any type B, an instance of a type derived from B is also an instance of B. There is no need to test for this explicitly.
Recommendation¶
Remove the useless type test.
Example¶
In this example class Sub extends class Super. A new instance of Sub, sub is initialized and checked to see if it is an instance of Super . Since Sub extends Super then there is no need to test that sub is a Super because it is guaranteed to be the case.
class UselessTypeTest
{
class Super { }
class Sub : Super { }
static void Main(string[] args)
{
Sub sub = new Sub();
if (sub is Super)
{
Console.WriteLine("Surprise! sub is a Super!");
}
}
}