From 4fa84830f8a91a2a8db988afec96b416ae2654c0 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 27 May 2016 21:57:06 +0200
Subject: [PATCH] improve E0152 error explanation

---
 src/librustc/diagnostics.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/librustc/diagnostics.rs b/src/librustc/diagnostics.rs
index 7c350987aa1e..a410a5949bdc 100644
--- a/src/librustc/diagnostics.rs
+++ b/src/librustc/diagnostics.rs
@@ -525,6 +525,17 @@ call to `mem::forget(v)` in case you want to avoid destructors being called.
 "##,
 
 E0152: r##"
+A lang item was redefined.
+
+Erroneous code example:
+
+```compile_fail
+#![feature(lang_items)]
+
+#[lang = "panic_fmt"]
+struct Foo; // error: duplicate lang item found: `panic_fmt`
+```
+
 Lang items are already implemented in the standard library. Unless you are
 writing a free-standing application (e.g. a kernel), you do not need to provide
 them yourself.