No. This is just a nitpick. What I mean is: 
If class C implements `f2(int)`, the error message "void f2(int) is not implemented" should not appear, but "void f2(float) const is not implemented" should.
That was well tested in original case, but you removed it.

To realize it, you can add only `void f2(int p) {}` in class C, and fix the diagnostic message according to it.