From 2610ab872a6a0b4174455b52de461655df59e5fe Mon Sep 17 00:00:00 2001
From: Henry de Valence <hdevalence@hdevalence.ca>
Date: Mon, 13 Mar 2017 16:28:43 -0700
Subject: [PATCH] Feature-gate basepoint table creation on a `nightly` feature

---
 Cargo.toml   | 3 +++
 src/curve.rs | 8 +++++---
 src/lib.rs   | 2 +-
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 691f464..f0189e5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -33,9 +33,12 @@ version = "^0.6"
 version = "0.4"
 
 [features]
+nightly = ["basepoint_table_creation"]
 default = ["std"]
 std = ["rand"]
 yolocrypto = []
+# Needs nightly for placement new
+basepoint_table_creation = []
 
 # The development profile, used for `cargo build`.
 [profile.dev]
diff --git a/src/curve.rs b/src/curve.rs
index f90e69b..054b164 100644
--- a/src/curve.rs
+++ b/src/curve.rs
@@ -81,9 +81,6 @@ use core::fmt::Debug;
 use core::iter::Iterator;
 use core::ops::{Add, Sub, Neg};
 
-#[cfg(feature = "std")]
-use std::boxed::Box;
-
 use constants;
 use field::FieldElement;
 use scalar::Scalar;
@@ -95,6 +92,8 @@ use subtle::CTNegatable;
 
 #[cfg(not(feature = "std"))]
 use collections::boxed::Box;
+#[cfg(feature = "std")]
+use std::boxed::Box;
 
 // ------------------------------------------------------------------------
 // Compressed points
@@ -831,6 +830,7 @@ pub struct EdwardsBasepointTable(pub [[AffineNielsPoint; 8]; 32]);
 
 impl EdwardsBasepointTable {
     /// Create a table of precomputed multiples of `basepoint`.
+    #[cfg(feature="basepoint_table_creation")]
     pub fn create(basepoint: &ExtendedPoint) -> Box<EdwardsBasepointTable> {
         // Create the table storage
         // XXX can we be assured that this is not allocated on the stack?
@@ -1312,6 +1312,7 @@ mod test {
 
     /// Test precomputed basepoint mult
     #[test]
+    #[cfg(feature="basepoint_table_creation")]
     fn test_precomputed_basepoint_mult() {
         let table = EdwardsBasepointTable::create(&constants::ED25519_BASEPOINT);
         let aB_1 = ExtendedPoint::basepoint_mult(&A_SCALAR);
@@ -1487,6 +1488,7 @@ mod bench {
         b.iter(|| p1.mult_by_cofactor() );
     }
 
+    #[cfg(feature="basepoint_table_creation")]
     #[bench]
     fn create_basepoint_table(b: &mut Bencher) {
         let aB = ExtendedPoint::basepoint_mult(&A_SCALAR);
diff --git a/src/lib.rs b/src/lib.rs
index bcacba1..b268354 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -11,9 +11,9 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(not(feature = "std"), feature(collections))]
+#![cfg_attr(feature = "nightly", feature(box_syntax))]
 #![allow(unused_features)]
 #![feature(test)]
-#![feature(box_syntax)]
 #![deny(missing_docs)] // refuse to compile if documentation is missing
 
 //! # curve25519-dalek