upgrade to byte_struct 0.6.1 causes problems

[jrandall]

Without making any code changes, our builds started failing at the end of the day yesterday, apparently due to changes in byte_struct 0.6.1, as our previous build that picked up byte_struct 0.6.0 was working fine.

         Checking byte_struct v0.6.1
     error[E0277]: the trait bound `[T; 1]: std::convert::From<std::vec::Vec<T>>` is not satisfied
        --> /build/lentil/build/home/.cargo/registry/src/github.com-1ecc6299db9ec823/byte_struct-0.6.1/src/lib.rs:416:40
         |
     416 |                 }).collect::<Vec<_>>().try_into().map_err(|_|()).unwrap()
         |                                        ^^^^^^^^ the trait `std::convert::From<std::vec::Vec<T>>` is not implemented for `[T; 1]`
     ...
     442 | bsa5!(1);

I'm not yet sure what the actual issue is here, but I would not expect patch versions to have changes that break backwards compatibility or require newer rust versions (here we are building this with rust 1.44.1).

[jrandall]

The referenced line was indeed changed in yesterday's release: a535678

[jrandall]

I can confirm that updating to rust 1.50.0 has made this error go away. It looks like there is considerable disagreement in the rust community as to how package versions should be updated when rust toolchain version requirements change, so perhaps there is nothing inherently wrong in this happening in a patch version.

On the other hand, it would be good to document the minimum rust version required (or perhaps a more general policy that the package is only tested against the N latest versions), and to test against that version (or those versions) prior to release?

[wwylele]

Oops, my bad. I didn't consider the problem of minimal rust version (and I probably had a false impression that this feature was there quite a while).

As you might have noticed, this package was created by me early in my rust journey, and yesterday's update was because of a unsoundness report (which I value a lot). Things wasn't really set up in a mature way (there isn't even CI testing it lol). I should take time to review this package again and make it a non-toy with what I have learned now.