Reduced test code:

```
int mem(char *data);
int cond(void);
void f(char *data, unsigned idx, unsigned inc)
{
    char *d2;
    int c = cond();
    if (idx >= 2) {
        if (c)
            d2 = data;
        mem(data);
    }
    else if (inc > 3) {
        if (c)
            d2 = data;
        mem(data);
    }
    else {
        if (c) {
            d2 = data;
        }
    }
    if (*data) {
    }
    else if (c) {
        mem(d2);
    }
}
```

Compiling with `gcc -Wall -Wextra -O{1,2,s,3,fast}` warns about

```
a.c: In function 'f':
a.c:27:9: warning: 'd2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   27 |         mem(d2);
      |         ^~~~~~~
```

However, it should be clear that `d2` is always assigned when `c` is true. In fact, it seems that GCC could figure this out in some cases. Changes that can surpress the warning includes,

1. Remove any of the `mem(data)` calls.
2. Remove any one of the `if`s (leaving only the if or else branch unconditionally)
3. Change first condition to be on inc instead.
4. Removing the last `*data` branch.

Version tested:
AArch64: 10.2.0
ARM: 9.1.0
x86_64: 10.1.0
mingw64: 10.2.0