[Bug c++/58569] Compilation error when a class contains multiple std::function

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58569

--- Comment #14 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
(In reply to Jonathan Wakely from comment #13)
> Argh, yes, I didn't read the diagnostic properly after that last change,
> sorry!

Thanks. I think the actual problem can be resolve by moving

  template<typename CallRes, typename Res1>
    struct CheckResult
    : is_convertible<CallRes, Res1> { };

out of the template. When this template is instantiated within the outer class,
the result is still an incomplete type. I think there was a core issue with
that out come.