Attempt to resolve this randomness mess

Cargo.toml

@@ -47,6 +47,7 @@ default-features = false
 [dependencies.rand_os]
 version = "0.1.3" # 0.2
 default-features = false
+optional = true
 
 [dependencies.rand_chacha]
 version = "0.1" # 0.2
@@ -88,10 +89,12 @@ harness = false
 [features]
 default = ["std", "u64_backend", "rand"] # "chacha"
 preaudit_deprecated = []
-chacha = ["rand_chacha"]
-std = ["curve25519-dalek/std", "rand/std"] # "failure/std"
-alloc = ["curve25519-dalek/alloc"]
 nightly = ["curve25519-dalek/nightly", "rand/nightly"] # "zeroize/nightly"
+alloc = ["curve25519-dalek/alloc", "rand_core/alloc"]
+chacha = ["rand_chacha"]
+std = ["rand_os", "curve25519-dalek/std", "rand/std"] # "failure/std"
+stdweb = ["rand_os/stdweb"]
+wasm-bindgen = ["rand_os/wasm-bindgen"]
 asm = ["sha2/asm"]
 yolocrypto = ["curve25519-dalek/yolocrypto"]
 u64_backend = ["curve25519-dalek/u64_backend", "ed25519-dalek/u64_backend"]

src/lib.rs

@@ -231,16 +231,17 @@ fn zeroize_hack<Z: Default>(z: &mut Z) {
 
 use rand_core::{RngCore,CryptoRng};
 
-#[cfg(feature = "std")]
+#[cfg(all(feature = "std", feature = "rand"))] 
 fn rand_hack() -> impl RngCore+CryptoRng {
-    #[cfg(feature = "rand")] 
-    { ::rand::thread_rng() }
+    ::rand::thread_rng()
+}
 
-    #[cfg(not(feature = "rand"))] 
-    { ::rand_os::OsRng::new() }
+#[cfg(all(feature = "rand_os", not(feature = "rand")))] 
+fn rand_hack() -> impl RngCore+CryptoRng {
+    ::rand_os::OsRng::new().unwrap()
 }
 
-#[cfg(not(feature = "std"))]
+#[cfg(not(feature = "rand_os"))]
 fn rand_hack() -> impl RngCore+CryptoRng {
     const PRM : &'static str = "Attempted to use functionality that requires system randomness!!";