> Hmm.. tried your example on 2.7.2 (mips) without any complaints (-Wall).
> But the above exapmple is maybe not represenative for the real code.

Here is a piece of code that closely resembles (in structure) some real code
in the sparc port. Note the spurious warning.

extern int a(void);
extern int g(int);

int
f(void)
{
        int x,y;

        x = 0;
        if (a()) {
                x = 1;
                y = 1;
		/* more */
        }

	/* more */
        if (x) {
		/* more */
		if (y) return 1;
		/* more */
	}

        return 0;
}