From 4146e1f02b45f548834a4e3507420ec18b725046 Mon Sep 17 00:00:00 2001
From: Robert Habermeier <rphmeier@gmail.com>
Date: Tue, 31 May 2016 21:18:54 +0200
Subject: [PATCH] add empty rule to map macros

---
 util/src/common.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/util/src/common.rs b/util/src/common.rs
index 2eb2ea017..0e0cd7757 100644
--- a/util/src/common.rs
+++ b/util/src/common.rs
@@ -26,6 +26,7 @@ pub use sha3::*;
 
 #[macro_export]
 macro_rules! hash_map {
+	() => { HashMap::new() };
 	( $( $x:expr => $y:expr ),* ) => {{
 		let mut x = HashMap::new();
 		$(
@@ -37,6 +38,7 @@ macro_rules! hash_map {
 
 #[macro_export]
 macro_rules! hash_map_into {
+	() => { HashMap::new() };
 	( $( $x:expr => $y:expr ),* ) => {{
 		let mut x = HashMap::new();
 		$(
@@ -48,6 +50,7 @@ macro_rules! hash_map_into {
 
 #[macro_export]
 macro_rules! map {
+	() => { BTreeMap::new() };
 	( $( $x:expr => $y:expr ),* ) => {{
 		let mut x = BTreeMap::new();
 		$(
@@ -59,6 +62,7 @@ macro_rules! map {
 
 #[macro_export]
 macro_rules! map_into {
+	() => { BTreeMap::new() };
 	( $( $x:expr => $y:expr ),* ) => {{
 		let mut x = BTreeMap::new();
 		$(