# V537. Potential incorrect use of item 'X'. Consider inspecting the expression.

The analyzer has detected a potential misprint in code related to incorrect use of similar names.

This rule tries to diagnose an error of the following type using the heuristic method:

    int x = static_cast<int>(GetX()) * n;
    int y = static_cast<int>(GetX()) * n;

In the second line, the 'GetX' function is used instead of 'GetY'. This is the correct code:

    int x = static_cast<int>(GetX()) * n;
    int y = static_cast<int>(GetY()) * n;

To detect this suspicious fragment, the analyzer followed this logic: we have a line containing a name that includes the 'x' fragment. Beside it, there is a line that has a similar name with 'y'. But this second line has 'X' as well. Since this condition and some other conditions hold, the construct must be reviewed by the programmer. This code would not be considered dangerous if, for instance, there were no variables 'x' and 'y' to the left. This is a code sample the analyzer ignores:

    array[0] = GetX() / 2;
    array[1] = GetX() / 2;

Unfortunately, this rule often produces false alarms since the analyzer does not know how the program is organized and what the code's purpose is. This is a sample of a false alarm:

    halfWidth -= borderWidth + 2;
    halfHeight -= borderWidth + 2;

The analyzer supposed that the second line must be presented by a different expression, for instance, 'halfHeight -= borderHeight + 2'. But actually there is no error here. The border's size is equal in both vertical and horizontal positions. There is just no 'borderHeight' constant. However, such high-level abstractions are not clear to the analyzer. To suppress this warning, you may type the '//-V537' comment into the code.

You can use another technique to prevent false positives. Below is the code fragment:

    bsdf->alpha_x = closure->alpha_x;
    bsdf->alpha_y = bsdf->alpha_x;

The code is correct. However, it looks suspicious, and not only from the analyzer's viewpoint. The developer who maintains the code will have a hard time understanding it. If you want to assign the same value to 'alpha_x' and 'alpha_y', you can write the following:

    bsdf->alpha_y = bsdf->alpha_x = closure->alpha_x;

This fragment won't confuse the developer and the analyzer won't issue a warning.

This diagnostic is classified as:

CWE-682

You can look at examples of errors detected by the V537 diagnostic.