# V3038. The argument was passed to method several times. It is possible that another argument should be passed instead.

The analyzer detected a possible error that has to do with passing two identical arguments to a method. It is a normal practice to pass one value as two arguments to many methods, so we implemented this diagnostic with certain restrictions.

The warning is triggered when arguments passed to the method and the method's parameters have a common pattern by which they can be described. Consider the following example:

    void Do(int mX, int mY, int mZ)
    {
      // Some action
    }

    void Foo(Vecor3i vec)
    {
      Do(vec.x, vec.y, vec.y);
    }

Note the 'Do' method's signature and its call: the 'vec.y' argument is passed twice, while the 'mZ' parameter is likely to correspond to argument 'vec.z'. The fixed version could look like this:

    Do(vec.x, vec.y, vec.z);

The diagnostic suggests possible correct versions of one of the duplicate arguments, and if the suggested variable is within the scope of the caller, a warning will be displayed with information about the suspected typo and the correct argument.

V3038 The 'vec.y' argument was passed to 'Do' method several times. It is possible that the 'vec.z' argument should be passed to 'mZ' parameter.

Another suspicious situation is passing identical arguments to such functions as 'Math.Min', 'Math.Max', 'string.Equals', etc..

Consider the following example:

    int count, capacity;
    ....
    size = Math.Max(count, count);

A typo causes the 'Math.Max' function to compare a variable with itself. This is the fixed version:

    size = Math.Max(count, capacity);

If you have encountered an error of this kind that the analyzer failed to diagnose, please email us and specify the name of the function that you do not want to receive one variable for several arguments.

Here is another example of an error found in real-life code:

    return invariantString
                    .Replace(@"\", @"\\")
                    .Replace("'", @"\'")
                    .Replace("\"", @"""");

The programmer seems to be unfamiliar with the specifics of string literals preceded by the '@' character, which was the cause of a subtle error when writing the sequence @"""". Based on the code, it seems the programmer wanted to have two quotation marks added in succession. However, because of the mistake, one quotation mark will be replaced by another. There are two ways to fix this error. The first solution:

    .Replace("\"", "\"\"")

The second solution:

    .Replace("\"", @"""""")

This diagnostic is classified as:

CWE-687

You can look at examples of errors detected by the V3038 diagnostic.