Make the alloc feature actually work.

Cargo.toml

@@ -22,6 +22,7 @@ arbitrary       = [ "quickcheck" ]
 serde-serialize = [ "serde", "serde_derive", "num-complex/serde" ]
 abomonation-serialize = [ "abomonation" ]
 debug = [ ]
+alloc = [ ]
 
 [dependencies]
 typenum        = "1.10"

src/base/default_allocator.rs

@@ -8,6 +8,9 @@ use std::mem;
 use std::ops::Mul;
 use std::ptr;
 
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::Vec;
+
 use generic_array::ArrayLength;
 use typenum::Prod;
 

src/base/matrix_alga.rs

@@ -1,3 +1,6 @@
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::Vec;
+
 use num::{One, Zero};
 
 use alga::general::{

src/base/matrix_vec.rs

@@ -1,5 +1,8 @@
 use std::ops::Deref;
 
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::Vec;
+
 use base::allocator::Allocator;
 use base::default_allocator::DefaultAllocator;
 use base::dimension::{Dim, DimName, Dynamic, U1};

src/lib.rs

@@ -85,6 +85,7 @@ an optimized set of tools for computer graphics and physics. Those features incl
 #![warn(incoherent_fundamental_impls)]
 #![doc(html_root_url = "http://nalgebra.org/rustdoc")]
 #![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(all(feature = "alloc", not(feature = "std")), feature(alloc))]
 
 #[cfg(feature = "arbitrary")]
 extern crate quickcheck;
@@ -113,6 +114,9 @@ extern crate typenum;
 
 extern crate alga;
 
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+extern crate alloc;
+
 #[cfg(not(feature = "std"))]
 extern crate core as std;