Hack: use chacha20 crate for StdRng and ThreadRng implementation

Cargo.toml

@@ -27,7 +27,7 @@ nightly = ["simd_support"] # enables all features requiring nightly rust
 serde1 = [] # does nothing, deprecated
 
 # Optional dependencies:
-std = ["rand_core/std", "rand_chacha/std", "alloc", "getrandom"]
+std = ["rand_core/std", "alloc", "getrandom"]
 alloc = ["rand_core/alloc"]  # enables Vec and Box support (without std)
 # re-export optional WASM dependencies to avoid breakage:
 # Warning: wasm-bindgen and stdweb features will be removed in rand 0.8;
@@ -73,14 +73,19 @@ libc = { version = "0.2.22", default-features = false }
 # Emscripten does not support 128-bit integers, which are used by ChaCha code.
 # We work around this by using a different RNG.
 [target.'cfg(not(target_os = "emscripten"))'.dependencies]
-rand_chacha = { path = "rand_chacha", version = "0.2.1", default-features = false }
+# rand_chacha = { path = "rand_chacha", version = "0.2.1", default-features = false }
+chacha20 = { path = "../stream-ciphers/chacha20", features = ["rng"] }
 [target.'cfg(target_os = "emscripten")'.dependencies]
 rand_hc = { path = "rand_hc", version = "0.2" }
 
 [dev-dependencies]
 rand_pcg = { path = "rand_pcg", version = "0.2" }
 # Only for benches:
 rand_hc = { path = "rand_hc", version = "0.2" }
+rand_chacha = { path = "rand_chacha" }
 
 [package.metadata.docs.rs]
 all-features = true
+
+[patch.crates-io]
+rand_core = { path = "rand_core", version = "0.5" }

src/rngs/std.rs

@@ -13,10 +13,12 @@ use crate::{RngCore, CryptoRng, Error, SeedableRng};
 #[cfg(all(any(test, feature = "std"), target_os = "emscripten"))]
 pub(crate) use rand_hc::Hc128Core as Core;
 #[cfg(all(any(test, feature = "std"), not(target_os = "emscripten")))]
-pub(crate) use rand_chacha::ChaCha20Core as Core;
+// pub(crate) use rand_chacha::ChaCha20Core as Core;
+pub(crate) use chacha20::ChaCha20RngCore as Core;
 
 #[cfg(target_os = "emscripten")] use rand_hc::Hc128Rng as Rng;
-#[cfg(not(target_os = "emscripten"))] use rand_chacha::ChaCha20Rng as Rng;
+// #[cfg(not(target_os = "emscripten"))] use rand_chacha::ChaCha20Rng as Rng;
+#[cfg(not(target_os = "emscripten"))] use chacha20::ChaCha20Rng as Rng;
 
 /// The standard RNG. The PRNG algorithm in `StdRng` is chosen to be efficient
 /// on the current platform, to be statistically strong and unpredictable