The following simple test program when compiled with -Wshadow produces no output. I'd expect to get warnings for both the x and y declaration in class B.

class A {
	static int x;
	int y;
};

class B : public A {
	static int x;
	int y;
};

int main()
{
	B a;
	return 0;
}

If this is intentional, perhaps another -W flag is appropriate. I spent about an hour trying to figure out why an app broke when I change a static class member declared in a class's header to instead be an anonymous global in that class's source file, and it was because all of the source file's references to the variable after the change went to a parent class variable of the same name and type rather than the global.