@fr00b0 FYI

Hello @kevin--
I'm not sure how what I think about this change. The library was always meant to be a C++ 11 14 library. I have not examined all of the things used to see if deprecation or behavior changes is present with C++ 20.

Edit: C++ 11 ofc, not 14...

@fr00b0 as we can see from https://en.cppreference.com/w/cpp/types/result_of the availability notes are

(since C++11)
(deprecated in C++17)
(removed in C++20)

The Notes section explains why result_of had some issues that lead to its eventual removal by the standards committee, and it seems that invoke_result provides identical results with less undefined behavior cases.

my proposed change leaves C++11 compatibility intact but allows me to keep using my favorite signaling library while building against the C++20 standard 🙃

@fr00b0 Can we get this accepted? I'd like to see @kevin--'s changes brought in since it leaves C++11 compatibility intact. I would like to keep using this library as well.

Merged to avoid this unfortunate situation with removal after deprecation in newer standards