nodrop: Add std as default feature to enable libstd

nodrop/Cargo.toml

@@ -12,6 +12,11 @@ repository = "https://github.com/bluss/arrayvec"
 keywords = ["container", "drop"]
 
 [features]
+default = ["std"]
+
+# Default, Rust 1.6+
+# Use libstd
+std = []
 
 # Optional, nightly channel
 # Use no drop flag. See API doc for more info.

nodrop/src/lib.rs

@@ -1,6 +1,10 @@
 //!
 //! The **nodrop** crate has the following cargo feature flags:
 //!
+//! - `std`
+//!   - Optional, enabled by default
+//!   - Requires Rust 1.6 *to disable*
+//!   - Use libstd
 //! - `use_needs_drop`
 //!   - Optional
 //!   - Requires nightly channel.
@@ -17,17 +21,17 @@
 #![cfg_attr(feature="no_drop_flag", feature(unsafe_no_drop_flag))]
 #![cfg_attr(feature="use_needs_drop", feature(core_intrinsics))]
 
-#![cfg_attr(not(test), no_std)]
+#![cfg_attr(not(any(test, feature="std")), no_std)]
-#[cfg(test)]
+#[cfg(not(any(test, feature="std")))]
-extern crate core;
+extern crate core as std;
 
 extern crate odds;
 
 use odds::debug_assert_unreachable;
 
-use core::ops::{Deref, DerefMut};
+use std::ops::{Deref, DerefMut};
-use core::ptr;
+use std::ptr;
-use core::mem;
+use std::mem;
 
 /// repr(u8) - Make sure the non-nullable pointer optimization does not occur!
 #[repr(u8)]