use const_random

Cargo.toml

@@ -21,6 +21,7 @@ bench-md = []
 bench-plot = []
 
 [dependencies]
+const-random = "0.1"
 rand_chacha = { version = "0.3", default_features = false }
 rand_core = "0.6"
 
@@ -71,4 +72,4 @@ harness = false
 
 [[bench]]
 name = "quality"
-harness = false
+harness = false

build.rs

@@ -2,25 +2,6 @@ extern crate rustc_version;
 use rustc_version::{version_meta, Channel};
 
 fn main() {
-    // generate seed for GxBuildHasher RNG if entropy isn't available
-    let entropy = cfg!(target_feature = "rdrand") || cfg!(feature = "std");
-    if entropy {
-        println!("cargo:rustc-cfg=entropy")
-    } else {
-        let out_dir = std::env::var_os("OUT_DIR").unwrap();
-        let seed_path = std::path::Path::new(&out_dir).join("seed.rs");
-
-        use rand::RngCore;
-        let mut seed = [0u8; 32];
-        let mut rng = rand::thread_rng();
-        rng.fill_bytes(&mut seed);
-
-        let mut string = "const SEED: [u8; 32] = [".to_owned();
-        string.push_str(&seed.into_iter().map(|i| i.to_string()).collect::<Vec<String>>().join(","));
-        string.push_str("];");
-        std::fs::write(seed_path, &string).unwrap();
-    }
-
     if version_meta().unwrap().channel == Channel::Nightly
     && cfg!(target_arch = "x86_64")
     && cfg!(target_feature = "avx2")

src/hasher.rs

@@ -136,17 +136,14 @@ impl Hasher for GxHasher {
 #[derive(Clone, Debug)]
 pub struct GxBuildHasher(State);
 
-#[cfg(not(entropy))]
-include!(concat!(env!("OUT_DIR"), "/seed.rs"));
-
 impl Default for GxBuildHasher {
     #[inline]
     fn default() -> GxBuildHasher {
         let mut uninit: MaybeUninit<State> = MaybeUninit::uninit();
         #[cfg(entopy)]
         let mut rng = rand_chacha::ChaCha12Rng::from_entropy();
         #[cfg(not(entropy))]
-        let mut rng = rand_chacha::ChaCha12Rng::from_seed(SEED);
+        let mut rng = rand_chacha::ChaCha12Rng::from_seed(const_random::const_random!([u8; 32]));
         unsafe {
             let ptr = uninit.as_mut_ptr() as *mut u8;
             let slice = core::slice::from_raw_parts_mut(ptr, VECTOR_SIZE);