From f51771939ba5b36ec89b9f0b51c2cbda51164676 Mon Sep 17 00:00:00 2001
From: Sean McArthur <sean.monstar@gmail.com>
Date: Wed, 7 Jun 2017 17:06:55 -0700
Subject: [PATCH] core: allow messages in unimplemented!() macro

---
 src/libcore/macros.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index bf4e414d41684..320d323684014 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -542,7 +542,8 @@ macro_rules! unreachable {
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 macro_rules! unimplemented {
-    () => (panic!("not yet implemented"))
+    () => (panic!("not yet implemented"));
+    ($($arg:tt)+) => (panic!("not yet implemented: {}", format_args!($($arg)*)));
 }
 
 /// Built-in macros to the compiler itself.