feature gate Alloc impls behind nightly

Author: creativcoder

wee_alloc/Cargo.toml

@@ -18,6 +18,7 @@ travis-ci = { repository = "rustwasm/wee_alloc" }
 
 [features]
 default = ["size_classes"]
+nightly = []
 
 # Enable extra, expensive integrity allocations.
 extra_assertions = []

wee_alloc/src/lib.rs

@@ -272,7 +272,9 @@ mod neighbors;
 mod size_classes;
 
 use const_init::ConstInit;
-use core::alloc::{Alloc, AllocErr, GlobalAlloc, Layout};
+#[cfg(feature = "nightly")]
+use core::alloc::Alloc;
+use core::alloc::{AllocErr, GlobalAlloc, Layout};
 use core::cell::Cell;
 use core::cmp;
 use core::marker::Sync;
@@ -1182,7 +1184,7 @@ impl<'a> WeeAlloc<'a> {
     }
 }
 
-#[cfg(nightly)]
+#[cfg(feature = "nightly")]
 unsafe impl<'a, 'b> Alloc for &'b WeeAlloc<'a>
 where
     'a: 'b,