CodeQL documentation

Impossible array cast

ID: cs/impossible-array-cast
Kind: problem
Severity: error
Precision: high
Tags:
   - reliability
   - correctness
   - logic
Query suites:
   - csharp-security-and-quality.qls

Click to see the query in the CodeQL repository

Some casts between array types are guaranteed to fail at runtime: the cast from Object[] to String[] will always fail, even if all the elements of the array are strings. Casts identified by this check either fail immediately, or (in the case of arrays with parameterized types) cause an InvalidCastException later on in the code.

Recommendation

Change the array creation expression to construct an array object of the right type.

Example

class ImpossibleArrayCast
{
    static void Main(string[] args)
    {
        // This will result in an InvalidCastException.
        String[] strs = (String[])new Object[] { "hello", "world" };
    }
}