# V2514. MISRA. Unions should not be used.

This diagnostic rule is based on the software development guidelines developed by MISRA (Motor Industry Software Reliability Association).

The analyzer issues the warning when it detects a union declaration.

Incorrect use of unions may cause various problems, such as reading incorrect values or undefined behavior.

For example, in C++, undefined behavior occurs when attempting to read from a member other than the one that the latest write operation was performed on.

Here is an example of code triggering this warning:

    union U
    {
      unsigned char uch;
      unsigned int ui;
    } uni;
    ....
    uni.uch = 'w';
    int ui = uni.ui;

This diagnostic is classified as:

MISRA-C-2012-19.2 MISRA-C-2023-19.2 MISRA-CPP-2008-9.5.1