Allow for constructing a constant Choice about subtle HOT 6 CLOSED

Can we make the From impl a const fn?

from subtle.

I'm not totally clear on the details but from https://varkor.github.io/blog/2019/01/11/const-types-traits-and-implementations-in-Rust.html it looks like it may be possible to just declare the From impl we have to be const.

from subtle.

In the future it will be possible to do this, yes, but I'm not optimistic about the timeframe. It's worth considering a temporary solution that can be deprecated later.

from subtle.

Ah, sorry, I misunderstood the blog post I linked -- I thought it was talking about the current design and not a future expansion. If you have a usecase for constructing const Choices, we could think about adding a from_const_u8 with a warning-of-future-deprecation.

from subtle.

In some of my code I have structures which contain a Choice to indicate something about the value (that it's the point at infinity), but when they contain a Choice I cannot create constant values (like the point at infinity) for the structure anymore.

from subtle.

I would be happy to add a from_const_u8 with a doc comment noting the potential for future deprecation if that PR existed, but I would prefer to close this issue as "resolved discussion" until then :)

from subtle.