No return value, but no warning?

[Jack Applin]

Consider this program fragment:

        class foo {
            public:
                ~foo() {}
        };

        double alpha(foo f) { }

        class bar {
        };

        double beta(bar b) { }

Compiling with g++ 2.95.2 produces:

        $ g++ -ansi -pedantic -Wall -W -c c.c

        c.c: In function `double beta(bar)':
        c.c:11: warning: unused parameter `class bar b'
        c.c:11: warning: control reaches end of non-void function `beta(bar)'

Why didn't alpha produce any warnings?  I suppose that, because foo
isn't POD, it can have an "active" copy ctor and dtor, and hence f is
implicitly used, so it's ok to omit the warning about an unused parameter.
However, why no warning about alpha not returning anything?

-- 
Jack Applin
address@hidden