Breakages with updating to 0.8.0 related to the OS random entropy changes

[sciguyryan]

Hi.

I know this is related to the re-configurations to do with the OS random changes, the following code:

Xoshiro512PlusPlus::from_os_rng(),

Was the way to do things, and I have no idea what the new method to achieve this is since the update guide for rand 0.10 isn't done yet: https://rust-random.github.io/book/update-0.9.html

Can anyone tell me what the equivalent is? I've tried picking through the change logs and I can't make any sense of what's been done and why. These things break spectacularly every few versions.

The only way I can figure out to do this presently as is as follows... but it is fugly and looks like something my dog ate and vomited back up:

let mut os_seed <Xoshiro512PlusPlus as SeedableRng>::Seed = Default::default(); OsRng.try_fill_bytes(os_seed.as_mut()).unwrap();

And then just seeding that the normal way. If that's the only way, it is what it is, but that just looks gross.

It's not just this either, it's broken fill, shuffle... and I could go on and on.

[dhardy]

There isn't a direct replacement, but you can for example do:

use rand_core::SeedableRng;
use getrandom::SysRng;

let mut rng = Xoshiro512PlusPlus::try_from_rng(&mut SysRng);

Or (once rand is updated):

use rand_core::SeedableRng;

let mut rng = Xoshiro512PlusPlus::from_rng(&mut rand::rng());

[sciguyryan]

Thank you. I appreciate you taking the time to respond, and for working on this stuff!

I can work with that. Not quite as ergonomic as the old way, but it's certainly better than my dog-ate-my-homework-and-vomited-it-back-up version above!

I'll just add a dependency on getrandom for it.

I'm also getting issues with things like this:

cell_list.shuffle(&mut rng);

Where rng there is an instance of the Xoshiro512PlusPlus struct that I had seeded. I'm getting more things have changed than I initially realised, I don't know.

I'll have to look at it all in the morning. I might just have to revert everything until things stabilise.

[dhardy]

rand hasn't been updated yet: see rust-random/rand#1729. Until then you will need to use an old release.

[sciguyryan]

rand hasn't been updated yet: see rust-random/rand#1729. Until then you will need to use an old release.

Oh, whoops. I guess I missed that one. D'oh. Thanks. I will close this and wait for everything to settle down then!

[dhardy]

We have added rand::make_rng() as a replacement for from_os_rng(): rust-random/rand#1734

Likely there will be a release out today.