From 39f318bb4d7144a8deb10f520a01164133c1b6ec Mon Sep 17 00:00:00 2001
From: Michael Layne <mlayne@fastmail.com>
Date: Thu, 18 Aug 2016 14:40:59 -0700
Subject: [PATCH] Update error format for E0232

---
 src/librustc_typeck/check/mod.rs | 9 ++++++---
 src/test/compile-fail/E0232.rs   | 5 ++++-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index ff0b86aa59540..3a21ffb5e7d93 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -903,9 +903,12 @@ fn check_on_unimplemented<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
                 }
             }
         } else {
-            span_err!(ccx.tcx.sess, attr.span, E0232,
-                                  "this attribute must have a value, \
-                                   eg `#[rustc_on_unimplemented = \"foo\"]`")
+            struct_span_err!(
+                ccx.tcx.sess, attr.span, E0232,
+                "this attribute must have a value")
+                .span_label(attr.span, &format!("attribute requires a value"))
+                .note(&format!("eg `#[rustc_on_unimplemented = \"foo\"]`"))
+                .emit();
         }
     }
 }
diff --git a/src/test/compile-fail/E0232.rs b/src/test/compile-fail/E0232.rs
index efeb869d71fa5..ce4f4638dac59 100644
--- a/src/test/compile-fail/E0232.rs
+++ b/src/test/compile-fail/E0232.rs
@@ -10,7 +10,10 @@
 
 #![feature(on_unimplemented)]
 
-#[rustc_on_unimplemented] //~ ERROR E0232
+#[rustc_on_unimplemented]
+//~^ ERROR E0232
+//~| NOTE attribute requires a value
+//~| NOTE eg `#[rustc_on_unimplemented = "foo"]`
 trait Bar {}
 
 fn main() {