From 9c325e79d3297484130fd84a703d35f2a73bc56b Mon Sep 17 00:00:00 2001
From: Ales Katona <almindor@gmail.com>
Date: Fri, 25 Jan 2019 16:02:58 -0700
Subject: [PATCH] reintroduce lock

---
 src/lib.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 7d165d8..907d648 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,11 @@ use crate::types::{InputCause, InputTypeFlags, ProcessingResult};
 
 pub mod types;
 
+
+// error out specifically if no backend is chosen
+#[cfg(not(any(feature="backend_piston", feature="backend_gilrs")))]	
+compile_error!("No backend selected, use features=<backend> in Cargo.toml or --features <backend> when building directly.");
+
 #[cfg(feature="backend_piston")]
 pub mod backend_piston;
 #[cfg(feature="backend_gilrs")]