# V2560. MISRA. There should be no user-defined variadic functions.

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

This diagnostic rule applies only to code written in C++. There should be no user-defined variadic functions (i.e. containing the ellipsis '...') in the code. Arguments passed using the ellipsis cannot be checked by the compiler for type compatibility and using them can, therefore, lead to errors. You may accidentally pass arguments of the wrong types to a function that is declared but not defined. Additionally, passing an argument of a non-POD type leads to undefined behavior.

Example of non-compliant code:

    void foo(int _, ...) // <=
    {
      va_list ap;
      va_start(ap, _);
      ....
      va_end(ap);
    }

The standard, however, does permit the declaration of existing library variadic functions. The following code is allowed:

    int printf(const char *fmt, ...);

This diagnostic is classified as:

MISRA-CPP-2008-8.4.1