Potential collision with C++20 module keyword

[dalboris]

Hi everyone,

I just wanted to bring to your attention that the name module is likely to become a keyword in C++20, which I believe would cause a collision with pybind11::module. Maybe you already know this, maybe not, but I thought I'd better write something here just in case.

Here is an interesting discussion from Vulkan facing similar problems: KhronosGroup/Vulkan-Docs#568

Related links:
https://www.reddit.com/r/cpp/comments/4b9qru/what_exactly_is_the_proposed_module_system_how/
https://clang.llvm.org/docs/Modules.html

[EricCousineau-TRI]

I guess this may not contribute much, but future proofing the library at least should be simple enough:

class module_ { ... };

#if !defined(PYBIND11_CPP20)
using module = module_;
#endif

[dalboris]

This makes sense to me :) Note that there's a typo in your post above (module = module), but you've corrected it in the PR. I haven't looked into the PR in detail, or tested the code, I just wanted to say that I agree with this general approach, and that if I was in charge I'd probably have done it the same way: there is already an underscore in class_ for the same reason.

[EricCousineau-TRI]

Thanks! And oops! Corrected.

[dalboris]

Closing this (see #1639).