Maintenance status of poly

[cstratopoulos]

Hello

Was wondering about whether folly/poly is being maintained and if PRs would be accepted. From what I've seen its tests are commented out in CI and its source files are unconditionally deleted on Windows builds.

I've been making some minor updates in a fork and I wanted to know if it would be possible to get them merged. In summary:

• add noexcept handling to type traits fixing Poly does not work with noexcept methods #737
• replace non-type template parameter auto detection macro since using __cpp_template_auto is deprecated on GCC and not supported on MSVC
• Some minor changes to SFINAE usage:
  • getOpsImpl
  • MetaDefer
• Helper rather than calling std::get with tuple inheritance, MSVC and clang-cl didn't seem to like this

Note that with the last few bullet points some testing on my local machine indicates that compiling/test passing with recent MSVC (16, definitely, 15.9.x maybe) should be within reach.

The only issue I've encountered is with non-member functions as it seems these require a lambda in an unevaluated context which I think lands in C++20 with p0315.

[Orvid]

Pull requests are welcome :)

The only reason it's commented out is because when Poly was first created I didn't have the time to go through and fix it to work on Windows, so I just disabled the test for the moment, and then proceeded to forget I'd done so :)

[cstratopoulos]

@Orvid cool! Would you prefer single-topic PRs for the bullets I outlined above (e.g, one for noexcept, one for the NTTP macro) or should I just open all in one go?

[Orvid]

Prefer separate PRs as it makes them easier to review and get landed.