cannot find function backup_entropy in this scope for wasm target even though source seed always provided

[krolaw]

Apologies for asking a question by using an issue - I'm new to rust, and I wasn't sure how to deal with this myself.

I am wanting to reliably reproduce/shuffle vast quantities of data in wasm (yew-rs) by way of a seed provided by a server:

let mut rng = WyRand::new_seed(server_seed);
rng.shuffle(&renumber);

I don't think I need an additional source of entropy, since WyRand reproduces the same data for the same seed?

error[E0425]: cannot find function `backup_entropy` in this scope
  --> /home/krolaw/.cargo/registry/src/github.com-1ecc6299db9ec823/nanorand-0.6.1/src/entropy/mod.rs:51:2
   |
51 |     backup_entropy(out);
   |     ^^^^^^^^^^^^^^ not found in this scope

Cargo.toml entry:

nanorand = { version = "0.6.1", features = ["wyrand"] }

Thanks.

[Absolucy]

For 0.8, I'll likely add an entropy feature, and without it, only SeedableRng instances can be crafted.

[emilpriver]

I downgraded it to 0.5.2 and it worked for me. running in Cloudflare workers with WASM.

[tungla20]

Hi @krolaw , how did you fix this issue? I tried nanorand = {version = "0.7.0", features = ["entropy, wyrand"]} but the compiler emit error

[krolaw]

I reimplemented WyRand that takes a seed. Code is very short, I'll post it there's interest.

[jklott]

@krolaw Would love to see your code and find out if it can be merged to main.

[krolaw]

It's not really suitable to merge into main. However, it is simple enough to copy to where you want it.

pub struct WyRand {
    pub seed: u64,
}

const P0: u64 = 0xa076_1d64_78bd_642f;
const P1: u64 = 0xe703_7ed1_a0b4_28db;

impl WyRand {
    pub fn rand(&mut self) -> u64 {
        self.seed = self.seed.wrapping_add(P0);
        let r = u128::from(self.seed) * u128::from(self.seed ^ P1);
        ((r >> 64) ^ r) as u64
    }

    pub fn range(&mut self, max: u64) -> u64 {
        self.rand() % max
    }
}