Why assign variable to itself [duplicate]

Question

A co-worker wrote a function like this (the comment was written by me):

static void foo(void *arg)
{
    //arg is NOT global variable
    arg = arg;
    // call other function, but doesn't use arg
    foo2();
}

Is there some reason to write code like this? Does it have some special purpose?

Answer 1

This is just one way of suppressing a compiler warning for an unused argument.

Other common methods are:

(void)arg;

or

#pragma unused (arg)    // not supported by all compilers