When should Halide transition to C++20?

[steven-johnson]

C++20 adoption is finally starting to pick up; we expect for at least one downstream blocker (Google) to enable it in the not-too-distant future. This is issue is meant to get feedback from downstream users to see whether use of C++20 in Halide would be a blocker for them, and if so, if there is any anticipated timeline for this to change.

(I'm not aware of anyone pushing to use specific C++20 features at this time; I mainly want to be sure that we are aware of any possible transition issues.)

From Google's point of view, I'd expect that C++20 usage would be feasible for Halide by end-of-year 2023 at the latest.

[steven-johnson]

Going to re-ping on this to see if we want to consider moving to this for Halide 18.

[abadams]

I just rechecked, and we're still a downstream blocker. Halide is used in a project that can't move to c++20 just yet (though it's in progress).