Update rand_macros to rust master
diff --git a/rand_macros/Cargo.toml b/rand_macros/Cargo.toml
index 0004074..00eecc5 100644
--- a/rand_macros/Cargo.toml
+++ b/rand_macros/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 
 name = "rand_macros"
-version = "0.1.5"
+version = "0.1.6"
 authors = ["The Rust Project Developers"]
 license = "MIT/Apache-2.0"
 readme = "README.md"
diff --git a/rand_macros/src/lib.rs b/rand_macros/src/lib.rs
index 5d1b289..3ecda88 100644
--- a/rand_macros/src/lib.rs
+++ b/rand_macros/src/lib.rs
@@ -67,7 +67,7 @@
         ),
         associated_types: Vec::new(),
     };
-    trait_def.expand(cx, mitem, item, |i| push(i))
+    trait_def.expand(cx, mitem, item, &mut |i| push(i))
 }
 
 fn rand_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {