Fix alloc feature in rand-core

Cargo.toml

@@ -18,7 +18,7 @@ default = ["std"]
 nightly = ["i128_support"] # enables all features requiring nightly rust
 
 std = ["rand-core/std", "winapi", "libc"] # default feature; without this rand uses libcore
-alloc = []  # enables Vec and Box support without std
+alloc = ["rand-core/alloc"]  # enables Vec and Box support without std
 
 i128_support = [] # enables i128 and u128 support
 

rand-core/src/lib.rs

@@ -34,6 +34,7 @@
 #![deny(missing_debug_implementations)]
 
 #![cfg_attr(not(feature="std"), no_std)]
+#![cfg_attr(all(feature="alloc", not(feature="std")), feature(alloc))]
 
 #[cfg(feature="std")] extern crate core;
 #[cfg(all(feature = "alloc", not(feature="std")))] extern crate alloc;