Support C++20 modules

[gracicot]

Is your feature request related to a problem? Please describe.

C++20 has added support for modules. A big feature we're looking forward is proper componentization. We declare many symbols in the detail namespace. Modules would allow us to only export symbols part of the public API.

Describe the solution you'd like
Since I also plan to support headers for a long time being, having headers with a KANGARU5_CXX_EXPORT that exands to export would add adequate support without sacrificing componentization or legacy support.

Describe alternatives you've considered
Nothing.

Additional context
Having the syntax import kangaru; would be the best.

[msqr1]

Hi, I have a tool that is perfect for this. Do you want to see a test run on the include directory? I am going to run it in transitional mode. @gracicot

[gracicot]

@msqr1 let me know how it goes! I would suggest you to try it on the dev-5.x.y branch, since this is where most recent work is done and C++20 is used

[msqr1]

@gracicot can you tell me what does the kangaru-prev folder do, and do I need to also modularize that ?

[gracicot]

@msqr1 this folder is temporary. It exists so I can keep my old unit tests around and port them to the new library gradually. It won't be there once released.

[msqr1]

So I would just ignore that one?

[gracicot]

@msqr1 yes, I would just ignore it :)