How to make gcc warn about returning the address of local variables?

Question

With gcc 4.4.5, I have a warning with the following code.

char *f(void)
{
    char c;
    return &c;
}

But, when I use a t

Answer 1

In this first example, gcc can clearly see you're returning the address of an automatic variable that will no longer exist. In the second, the compiler would have to follow your program's logic, as p could easily point to something valid (e.g. an external character variable).

Although gcc won't complain here, it will warn with pointer use like this:

char *f(const char *x)
{
  char *y = x;
  ...
}

Again, it can see without any doubt that you're removing the 'const' qualifier in this definition.

Another utility that will detect this problem is splint (http://splint.org).