# V1051. It is possible that an assigned variable should be checked in the next condition. Consider checking for typos.

The analyzer has detected a situation where a variable is initialized or assigned a new value and is expected to be checked in the condition of a subsequent 'if' statement but another variable is checked instead.

This error is demonstrated by the following example:

    int ret = syscall(....);
    if (ret != -1) { .... }
    ....
    int ret2 = syscall(....);
    if (ret != -1) { .... }    // <=

Programmers often need to check the value returned by a function but use a wrong variable name in the condition of the 'if' statement. This mistake is typically made when you clone a code fragment but forget to modify the name of the variable in the condition. In the example above, the programmer forgot to change the name 'ret' to 'ret2'.

Fixed version:

    int ret2 = syscall(....);
    if (ret2 != -1) { .... }

The following example also demonstrates this mistake:

    obj->field = ....;
    if (field) ....;

Both the variable and the class member have the same name, which makes it easy to confuse one with the other.

This diagnostic is heuristic; it splits the names of variables into individual strings and compares the respective parts to conclude if there is a typo. It also performs a basic type check, aiming at reducing the number of false positives.

The diagnostic may often be triggered by code like this:

    var->m_abc = ....;
    var->m_cba = ....;
    if (var->m_abc)      // <=
    {
      ....
    }

Fragments like this are usually correct. You can either suppress such warnings or swap the assignments so that the variable to be checked is assigned a value immediately before the 'if' statement:

    var->m_cba = ....;
    var->m_abc = ....;
    if (var->m_abc)
    {
      ....
    }

Keeping the assignment and the check close to each other also makes the code more readable.

This diagnostic is classified as:

CWE-754

You can look at examples of errors detected by the V1051 diagnostic.